Study of various coal mines in Utah, Colorado, and Wyoming

In preparing this thesis, some of the prominent coal mines in the states of Utah, Wyoming and Colorado were visited. These included the Sunnyside, Castle Gate, Geneva Coal and Kenilworth mines in Utah; the D. 0. Clark, Reliance, and Stansbury mines in Wyoming; and the Imperial and Eagle mines in Colorado. The first part of the thesis contains descriptive information of each mine. This includes the stratigraphy and geology of the respective areas and also the mining methods and types of equipment employed underground. Also presented is a criticism of certain systems as used under the certain prevailing conditions. The second part is mainly a comparison involving Economics;, safety, recovery percentage and the production rates of the mines. These are compared with a view to the methods being used underground. All of the mines studied have adopted the room-and-pillar method with the use of shaking conveyors, mobile loaders or a combination of the two. Therefore, the specific comparisons are based chiefly on the adaptability and productivity of the systems employed under the prevailingnatural or physical conditions. However, the factors involved in comparing the mining methods are so complex and variable that ideal exactitude is difficult.

OP GOAL in UTAH, COLORADO, AND WYOMING by Hasan H. Mumcu w -/c -}$• -Sc A Thesis Submitted to the Faculty of the University of Utah in Partial Fulfillment of the Requirements for the Degree of Master of Science in Mining Engineering May 15, 1950 Approved by STUDY OF VARIOUS COAL MINES UTAH, COLORADO, AND VVYOMING by Hasan H. Mumcu ' " l " . ,",', : ",: ; ,t : ,", f ' ,', ', , ' ,' . '. < , ' , ', \ , ( , " ' ' f " t , f , I. " ,: , ,f " 1:' - '; ~ ~ ~: :.~ ,'; "~ ~', : ',,:' • ' , • I : : • ; " , 0 , • " ' This thesis is a record of the visits and first hand studies of various coal mines in the states of Utah, Colorado, and Wyoming on Mining Methods by Hasan H. Mumcu by: Dr. P. "J. ^Shenon Head of the Mining Department on Mining Methods by Hasan H. Mumcu Approved Read 265232 AC KNOWLEDGMENTS Acknowledgment is gratefully made to Dr. P. J. Shenon, Head of the Mining Department, Professor J. E. Willson, at the University of Utah, under whose supervision this thesis was prepared. Their suggestions for the arrangement of the thesis and the devotion of their time to discuss certain problems is deeply appreciated. Sincere thanks are also due to Mr*. G. F. Jackson, and Professor R. P. Pull, Mining Department at the University of Utah, for their cooperation. The writer is grateful to the following companies and their kind officials for making available the opportunity of visiting their mines, their generous cooperation, and permis­sion to use some of their illustrating figures: Mr, W. Clarke, General Manager, Mr, G. B. Jackson, General Superintendent, Mr. E. 0. Jackson, Superintendent of the Independent Coal and Coke Company; Mr. C. P. Heiner, President, Mr. W. B. Odendahl, General Superintendent, Mr. R. Taylor, Chief Engineer of the Utah Fuel Company; Mr. P. V. Hicks, General Superintendent, Mr. J. Birk, Engineer of the Geneva Steel Company; Mr. H. C. Livingston, Vice President, Mr. V. 0. Murray, General Manager, Mr. J. B. Hughes, General Superintendent, Mr- P. B. Peternell, Safety Engineer of the Union Pacific Coal Company; and Mr. J. Brennan, President, and Mr. P. Kolar, General Superintendent of the Imperial Coal Company. Special acknowledgment is due to Coal Age and Mechanization I ACKNOWLEDGMENTS tim~ r~. Full, coopeDation. Mr. Mr. 1~. O. P. Helner, ~~. F. N~. O. lVIr. F. W~. F. magazines for the use of certain facts and illustrations, which they freely gave. II Ill Chapter I. Introduction 1 • . 3 Method 5 % Pace Preparation . . . . . . . . . . 7 Haulage 8 Ventilation 9 III. Castle Gate Mine, "D" Seam Location 10 Seam Characteristics and Geology . . 10 Mine Layout 11 Mining Method . . . 13 Room and Pillar Work 14 Face Preparation 14 Haulage 15 Ventilation 1© IV. Kenilworth Mine Location 17 Seam Characteristics and Geology ... 17 Mine Layout # 18 TABLE OP CONTENTS Page OF Part One: . . . . . . . . . . . Description of Mines II. Sunnyside Mine Location 0 0 0 • 0 0 0 • • • • • • 0 2 Seam Characteristics and Geology •• 2 Mine Layout .••. 0 0 •••• 0.0 Mining Method. • • • . . · . . . . . Room and Pillar Work 0 • · . . . . . Face • • 0 • • • • •• Roof Support 0 • • • • • • • • • ••• 8 . . . . • . . . . . . . . .. Ventilation. . 0 0 • • • · . . . . . • • 0 • • • · . . . . . • 0 • • • · . . . .. • • 0 • · . . . . . o. Work. · . . . . . .. Preparation. . • . • . • • •• . • • . . . . •• . . . • • 0 . . . · . . . . . .. · . . . . . . . · . . . • 0 • o • • 16 ••••••••••• •• 18 III IV" Chapter Mining Method Room and Pillar Work . 20 Pace Preparation 23 Haulage 24 Ventilation 25 V. Geneva Coal Mine Location 26 Seam Characteristics and Geology • •• 26 Mine Layout 27 Mining Method 29 Room and Pillar Work 30 Pace Preparation 32 Haulage . • 32 Ventilation 34 VI. D. 0. Clark Mine Location . . . . . . . . . . . . . . . 35 • .. 35 • 3$ Mining Method 37 Pace 43 44 ... • • • • • • pillar vVork • • · . . . . . . . . . . Page 20 Face • • •• .....0 • 0 • • • 0 • • • • 0 • 0 • 0 0 • . . . · . . . · . Vo •. . . . . . . . . . 0 00 0 •• '" 0 • • • •• Minine; Me thod. .•.•.• ••• · . • Face •.• 0 ••• 0 ••• • 0 • • • • • • • • • • • • • • O. Location. . . . . . . . . . . Seam Characteristics and Geology Mine Layout • • • . 0 0 0 • • • • • . .. • • 0 • Me thod • • • • . • • • • • •• Pillar Extraction 0 0 • • • • • • 40 Face Preparation Haulage • . . • • . . . . . . . . . . • • • • • • • • • • Ventilation • • . . . . . . • 0 0 • • VII. Stansbury Mine No. 1 Seam Location •• . . . . . . . . . . . • • 42 42 Seam Characteristics .and Geology •• o 44 v Chapter Mine Layout 45 Mining Method 45 Face Preparation 47 Haulage 47 Ventilation 49 VIII. Reliance Mine No. 11 Seam Location 50 Seam Characteristics and Geology •• 50 Mine Layout ...... 51 Mining Methods 51 Face Preparation . . . . . . . . . 53 Haulage 53 Ventilation 54 IX. Imperial Mine Location . . . . . . .. 55 Seam Characteristics and Geology •• 55 Mine Layout 55 Mining Method • 57 Barrier Extraction • 59 Face Preparation 59 Haulage 61 Ventilation 61 X. Eagle Mine Location • • . 64 Seam Characteristics and Geology • • 64 Mine Layout . . 64 Mining Method 65c • • • • • • • • • • IvJethod · • · • • • · • · • · • • . · • • · · • • • • · • • • • • I\;Tine • · . Charac~eristics • • • nUning • · • • · · • IvIine • . • • • • • • · • • • · · · . • • • · • • · • • · • . · • • • • • • • • • • • • • • . .. • • • • • • • · • • • • • • • • • • • • · · • • . . • · . • • · • • • · • • . . .. · . • • • · . . • • • • • • Page • • • • • · . . . . . . . · . . • • • •• 65 :V VI Chapter Room and Pillar Work 6«5 Pace Preparation 6,6 Haulage • • Ventilation . . Part Two: Comparisons XI. Criteria of Comparison §§ XII. Comparison . . 7© General •••• $Q Mining with Hand Loading 70 Shaking Conveyors 71 Track-mounted Mobile Loaders . . . 1% Crawler-mounted Mobile Loaders. . • 72 Continuous Mining Machine 7<& Pillar Extraction Methods 75 Face Preparation • . • 76 Transportation . . . . . . 77 • . . . . . . . . Face • • • • • • • • • o • . . . · . . . . . . . . .. 0 . . . . . . . . . Page 6~ 66 67 •• 0 0 • 0 00 GS • 0 • • • • • 0 • • • • o. '(JO • 0 . . . . . . . . . • • • • • • • • • • • • • · . . . • • • • • • • • • e· • · . . . • 0 . . . . . . . • •• • 0 • tlO 7~ 74 76 7rJ VII LIST OF FIGURES Figure Page 1. Layout Map of Sunnyside Mine 4 2. Pillar Extracting Method at Sunnyside Mine . 6 3. Face Preparation Diagram at Sunnyside Mine . 6 4. Layout Map of Castle Gate No. 2 Mine . . . . 12 5. Layout Map of Kenilworth Mine • 19 6. Retreat with Rope Haulage on Panels at Kenilworth Mine 7. Face Preparation at Kenilworth Mine 22 8. Layout Map of Geneva Coal Mine 23 9. Raise Mining System and Pillar Extraction with Shaking Conveyor at Geneva Coal Mine, . 31 10. Layout Map of D. 0. Clark Mine No. 7 Seam. . 36 11. Method of Extracting Room and-Entry Pillars with Duckbill-Shaking Conveyors at Union Pacific Coal Company1 s Mines 38 12. Cross Sections of Seams of D. 0. Clark Mine . 39 13. Shakers and Shuttle Ca ^ in Panel Work at D. 0. Clark Mine 39 14. Drilling Plan at D. 0. Clark Mine 41 15. Layout Map of Stansbury Mine No. 1 Seam ... 46 16. Drilling Plan at Stansbury Mine 48 17. Layout Map of Reliance Mine No. 11 Seam . .. 52 18. Drilling Plan at Reliance Mine . . . . . . . 48 19. Layout Map of Imperial Mine 56 20. Timbering and Room Work at Imperial Mine . . 58 . • . • • • • • • Mine. • • •• JI''Iine • • • • • • • • • • • • • . • • • • • • •• 22 Mine. • ••• • • . • • •• Mine.. O. Seam.. ~tracting Company's Mines. • • • • • •• O. Mine. Car o. • • • • • • • • • • • • •• o. • • • • •• ••• . . . . • •• ••• • • ••••• • • . • . .. . .. • • 58 VIII Eigure Pager 21. Pillar Pulling with Shaker at Imperial Mine. 58 22. Barrier Recovery in Imperial Mine 60 23. Pace Preparation at Imperial Mine 60 24. Layout Map of Eagle Mine 63 Pagw . . . . . Face . • • • • • . • • • . • • • • I INTRODUCTION In preparing this thesis, some of the prominent coal mines in the states of Utah, Wyoming and Colorado were visit­ed. These included the Sunnyside, Castle Gate, Geneva Coal and Kenilworth mines in Utah; the D. 0. Clark, Reliance, and Stansbury mines in Wyoming; and the Imperial and Eagle mines in Colorado. The first part of the thesis contains descriptive in­formation of each mine. This includes the stratigraphy and geology of the respective areas and also the mining methods and types of equipment employed underground. Also presented is a criticism of certain systems as used under the certain prevailing conditions. The second part is mainly a comparison involving econ­omics, safety, recovery percentage and the production rates of the mines. These are compared with a view to the methods being used underground. All of the mines studied have adopt­ed the room-and-nillar method with the use of shaking convey­ors, mobile loaders or a combination of the two. Therefore, the specific comparisons are based chiefly on the adaptabil­ity and productivity of the systems employed under the pre­vailing natural or physical conditions. However, the factors involved in comparing the mining methods are so complex and variable that ideal exactitude is difficult. CHAPTER ColoBado O. and-nillar variable that ideal exactitude is difficult. 1 OP •}»" *Vi* "X" PART ONE DESCRIPTION OF MINES 2 CHAPTER II SUNNYSIDE The Sunnyside No. 1 Mine, a property of Utah Fuel Company, is situated at Sunnyside, Utah, 150 miles south­east of Salt Lake City and 28 miles east of Price, Utah. Utah State Highway No. 123 passes through the town of Sunnyside. The history of the mine dates back to 1900, and to­day it is one of the modern mines in the West. At present, it is employing an average of 110 men underground, and pro­ducing about 2,000 tons of coal per three-shift day. Seam Characteristics and Geology.- The rank pf the Sunnyside coal is sub-bituminous, and it is of Upper Cre­taceous age, Mesa Verde group. _The coal measures, in this district, are composed of two seams, that is, the Upper and Lower Sunnyside seams. These two seams are separated by layers of interbedded sandstone and shale from 35 to 40-ft. in thickness. The upper seam, which ranges in thickness from 2 to 6-ft., is not mined. The Lower Sunnyside seam, which ranges in thickness from 6 to 14-ft., is being mined. In this seam there is a rock parting of from 15-in. to 6-ft. thick, mainly in Dip No. 2 sections, with the mineable coal underneath it. Toward the southeast the parting disappears, but the thickness of feeam drops from 14 to 9-ft. This rock parting where not removed with the coal, forms a bad roof because of its poor cementation characteristics with coal. SU1~YSIDE NO. 1 MINE mile.s south-east to-day At pro-ducing cOal three~s~lft Geology.-- of .co~l j,~.~lilJ-:bi twn:inol1.s, audit Cre-taceous .~ -- ------~. - - ., .. _- th~t ft. ft., ft., l5-:No. seam ft. In places where no parting is present, sandstone and hard shale make a fairly strong roof. The area is badly faulted (See mine layout map showing faults) in places and this has marked effect on the mining operation. The coal is massive in structure, and shows little evidence of bedding. It has a low sulphur and ash content, and is good coking coal. The seam dips in a northeasterly direction at the rate of 16 -percent near the outcrop and 10 percent at the inby end of the slopes. Mine Layout.- The mine is entered through a slope starting at the outcrop, on a dip of 12 percent. This slope entry connects with the Main North at a distance of 1,100-ft. from the outcrop. The Main North, which is driven on strike, consists of two entries, each 18-ft. wide and on 60-ft. centers. Pig. 1. Prom Main North three sets of slope entries are driven off down the dip approximately at right angles to it. The set through which the mine is entered, is called the "Outside Slope." The other two are "Dip Slope 1 and 2." The distance between the Outside Slope and Dip Slope 1 is 5,400-ft. Dip Slope 2 is 2,400-ft. beyond. Dip Slope 1. Strike entries are driven at right angles off the dip slopes to the right and left at about 450-ft. intervals. These are 18-ft. wide and on 80-ft. centers. The system of mining, due to the geologic conditions, has varied. Some are percent " Layout.-- 1,IOO-ft. IS-ft. Fig. From approxulately IIDip and2. tI ft. ft. ft. IS-SO-ft. 3 ~--------------~~~~--~----------------- -.. " ... .. -.... " .. • , • I -.. . .. .... , rite I -H'M La, .. , ., $., •• ,.,. N •• I Mifte D, Uta. F.!I Co ... ,. •• , ( M.~" •• 'a a ti_", M .. , " ... ) 5 two, and others three entry systems. Slants (cross-cuts) are spaced on 150-ft. centers and are 18-ft. wide. Mining Method.- The room-and-pillar method of min­ing is well adapted; with the use of a varie.t.y-of -..me.ehani-cal loading equipment, including track-and-craw mobile loaders, duckbill shaking conveyors, and continuous miner. Each type of equipment is worked as a separate unit. Track-mounted units, including a universal type cutting machine with electric drill and tr^ck-mounted loader, are employed in driving entries. These track-mounted 360 Good­man loaders load one car at a time. The loaded car is de­livered to the switch and an empty one placed next to the loader. In trackless sections, crawler-mounted loading machines, short wall cutting machines and post mounted electric ©ooley drills are used with the shuttle cars. The duckbill shaking conveyors are used chiefly In driving rooms and pulling pillars. In development work, up to 4-ft. of top coal is being left for protection against roof falls. Top coal is not left while drawing the pillars. de­velopment work. the face, and loads it onto a surge bin car at a high speed. However, it is not giving satisfactory results. It is further discussed in the second part of the thesis, and after certain problems rt. rt. Method.-- and-pillar. ~~_t!?-()~of min-mobile miner. Eac_h t;)TPeo~~~~ipmen_t_~~ work~~_as a separate unit. tr~ck-mounted mounted Good-man de-livered to the switch and an empty one placed next to the loalller. mounted Dooley in nillars. v:ork, be ing Drotection ~hile The continuous miner is being experimented with in de-velopment rlork. This machine digs the coal from .the fac_e, Car I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I Tr..„ F"?9. 2. - Pilfa-r fxtra-ctin^ Method at St/nnyside Mine. Ft'o. 3 - f**c9 Preparation Dfagrum at Sunnytfdt M>ne I =t=1 t::1 t=t +=1 t:1 ::t:1 +=1 +:1 :t:1 :::t:1 +' 1 =t1::::t:14~::t1 ::::t:1 ::tl :::t:1 ::::t:1 ::tl ::::t:1 :::t:1 ::tl ::t:1 :t:1 ::t:1 :t::1 t::1 ~I I~T r.c Ie II -,.- /1 00 ~ 0O-- "r , " " ,. " .. I, i' .' o. I, " .. II '~6· '. II " II .. , - " .' " " " II .' " " " " II " "" II ,I ,. .' " " /, .' ., " "" .. I t .. '': .. :": '/ L 0 • 0 0 0 • • 0 0 ,~' r- 0 0 0 0 S' . 'aCC V".W I ~ ... t •• • ,<.i.~ .".fI • f,l..,,r" Fi,- 3 - Fa.tc Pre,,,,tJ rloft D,..,,.&,,, CIt S ",mYf'd'e Mine. • are solved, may prove satisfactory. 7 Room and Pillar Work.-- Upon completion of the devel­opment work, rooms are driven from the strike entries to the rise on 60-ft. centers, each being 24 to 30-ft. wide. Rooms are driven at 20 degrees to the strike entries in duckbill-shaker territories, and at 60 degrees in mobile loader sections. Pillar extraction is conducted in the manner illustrated in Figure 2, which might be called a combination of the open-end and splitting methods. As shown in the figure, the cuts 1, 2, 3, 4, 5, 6, 7, and 8 are taken first, then the rest is mined by splitting in the following order: split I is driven; from split I the stump "a" is removed; split II is driven and from split II the stump "b" is removed; the stump "c" is re­moved from the entry. This method of extraction will give more recovery than the ordinary split method. Face Preparation.- The face, in driving entries, is prepared in the order shown in Figure 3. Track-mounted cutting-shearing machines undercut to a depth of 9-ft. and cut a center shear, also 9 ft. in depth, half-way up the face. Five top, 4 middle, and 4 bottom holes are drilled to a depth of 8.5-ft. using two set-ups of the drill post. That is, first the drill post Is set on one side of the face and 7 holes are drilled; then it is set on the other side of the Work.-- ft. duckbill­shaker 68 open­end rra" bl! "C" Preparation.-- mounted way f'ace. ft. ups is ('!rilled; s ide " 8 face and the rest of the holes are drilled. Therefore, the rib holes are drilled straight, and the center holes angled in, producing a V-cut. The holes are shot in two series, shearing are ignored, and the shooting is done on the solid with 14 holes. These holes are drilled in the same manner exception­ally consisting of from 3 to 4 sticks. Charges are properly stemmed to the collar of the holes, and the holes are fired simultaneously. Drilling and shooting methods vary under different conditions. Roof Support.- Each district has its individual tim­bering standards, due to the varied conditions. Such condi­tions are faulted sections, and changes in thickness of the immediate roof with its inconsistent shale content. From 2 to 3 rows of timbers with cap pieces are used where needed. No timber is recovered. Haulage.- Transportation is accomplished by a combina­tion of rope haulage and electric-locomotive track haulage. Loaded 5.7-ton mine cars are assembled in strike entries by 8-ton cable reel gathering locomotives. They are then hauled ! \ the middle and the center ones first, then the top holes. In pillar extraction and in rooms, undercutting and as described above. In sections where the roof is exception-ally tender, a top cut, a bottom cut and a shear cut are made. Permissible sheathed explosives are used, each charge /' Support.-- tim-bering condi-tions iw~ediate Haulage.-- combina-tion locomotive haulage •. gathering. to the partings of Dip Slope 1 or 2 and transferred to the rope haulage system. Coal from the room-and-pillar sections is discharged from conveyors or shuttle cars into mine cars and they are gathered similarly and pulled by locomotives to dip slopes partings where the trips are transferred to rope haulage. All transportation in slope entries, including the Outside Slope, 1st and 2nd Dips, is done with rope haulage. Loaded cars raised in the slopes are transferred at the Main North parting for haulage to the Outside Slope by 15-ton trolley locomotives that haul trips of 12 loaded cars. All haulage by rope or electric locomotives is coordin­ated in a smoothly running system, even though natural condi­tions present a difficult problem. Trolley phones are instal­led underground and on locomotives, providing a quick and effective communication system. The track on strike entries is 40-lb. rail and on Main North, 60-lb. Wooden ties and a 40-in. gauge are used. Ventilation.- Two exhaust fans supply the fresh air to the mine at the rate of 240,000 CFM. These fans are mounted on the_ surf ace and are offset from return airways. Since the mine is classed as gassy, no tubing blower fans are allowed underground, but brattice lines serve the samejpurpose• These brattice lines supply fresh air from the first inby cross-cut to within 15 or 20-ft. of the advance working face. The ventilation system is equipped with safety features, including safety signals and sirens. Stoppings and overcasts are air tight and put where necessary. 9 and-pillar Imulage. outside haula~~_~!E.C?:e~or s¥stem, naturalQOndi­tions locom0"t..:i.Y_E}.s I. -.~ ~- -- - -. communicati~n 1b. Ventilation.-- suppl.y o-f.?1Q.I.99P l1hesefans ...... -.~" ... - the surface _ • _______ <o. ____ ---.------~---.-".-.- .- •• - •• "..... • ••• - tubing.blower ., -~.- ..... ~,' . . s~e. .... purpose. ft. overgasts t:tght necessary_ CHAPTER III CASTLE GATE MINE, "D" SEAM Castle Gate Mine, a property of Utah Fuel Company, is located at Castle Gate, Utah, about 2 miles east of U.S. Highway No. 6, and 5 miles northeast of Helper. Use is made of track- and trackless-type mobile loaders and duckbill shaking conveyors in mining the coal. The mine, at present, is producing an average of 2,500 tons a day and employing from 260 to 265 men underground. Seam Characteristics and Geology.- In the Castle Gate Quadrangle, several coal seams are present, but only 4 or 5 of them are of economic importance. These seams named in order from the lowest up are: Castle Gate "A", Castle Gate "B", "Royal Blue", Castle Gate "C", and Castle Gate "D", or "Kenilworth." The Castle Gate "D" seam is being mined at the Castle Gate and Kenilworth mines. All these coal seams occur in the Blackhawk coal-bearing formations of the Mesa Verde group, and are Upper Cretaceous in age. The Blackhawk formation, in this quad­rangle, ranges from 900 to 1300-ft. in thickness, consist­ing of massive gray sandstone, sandy shale and coal beds. The coal beds are generally free from bone and shale part­ings, and range in thickness from a few inches up to 24-ft. The coal is of bituminous rank. The coal bearing rocks are affected by faults at only D" and Geology.-- C Il , Cas tIe coal­bearing l300-ft. ft. 10 a few places. These faults have a small vertical displace­ment and small horizontal offset. The ,rD,f seam crops out about 175-ft. above the "A" seam; it ranges in thickness from 14 to 24-ft. and is under a cover varying from 1,500 to 2,000-ft. The roof consists of sandstone, limestone and shale, and varies from strong to weak as the shale content increases. The bottom is of shale and forms a fairly good floor. The seam dips about 10-12 percent to the north. The coal is massive in structure, with little evidence of bedding. It is non-friable and strong. In this seam there is a rock parting which ranges from 0 to 6-ft. in thickness and makes the mining operation somewhat difficult. In development work, 6-ft. of top coal is left. Mine Layout.- The mine is entered through a rock tunnel which is 24-ft. wide and single tracked. This tunnel leads to the Main Haulage way,, 1st Dip Slope, and 2nd Dip Slope. Pig. 4. The First Dip Slope is driven down the dip of the seam at approximately right angles to the Main Haulage way as a two entry system. This First Dip Slope has a pitch of around 11 percent. About 2,200-ft. beyond the First Dip Slope is the Second Dip Slope, driven down at approximately an angle of 45 degrees to the Main Haulage way and in a northeasterly direction. The Second Dip Slope co insists of 4 sets of entries and has a pitch of about 3 percent for a distance of 3,000-ft., s~~ll ITDfI seam crops out about l75-ft. above the "A" ft. s~le, 11 friable ft. ft. Layout.-- way" Fig. ft. do-wn nsists ft., i.J '2 Z Z Nd I z '~..-.....' i.J :3 L.. ~ '4": I- """ ~ :3 '"" ~ "- 13 whereupon it runs parallel to the First Dip Slope and assumes the same pitch. From Dip Slopes No. 1 and 2, the strike entries are driven off to the right and left approximately on the strike of the s e am. The Main Haulage road is a double entry!system and is driven 24-ft. wide, on 70-ft. centers. All the slopes and entries are 18-ft. wide and are also on 70-ft. centers. Mining Method.- The retreat system of room-and-pillar method of mining has been adopted with the use of a variety of mechanical loading equipment, including track- and crawler-mounted mobile loaders and duckbill equipped shaking conveyors. Track-mounted units including 7 AU-cut and drill machines and Goodman type loaders., are used in driving entries. These loaders in the entries load one car at a time, and wait until the next empty car is brought. Crawler-mounted loaders (11 BU, cable reel type), 7B shortwall cut and drill machines, 10 RU rubber tired cut and drill machines and post mounted auger type drill machines are used in the trackless sections with shuttle cars, or with shaking conveyors. In panels on the east side of Second Dip Slope, the shuttle cars are used in combination with shakers. A Joy loader fills the shuttle car in the room or crosscut, which then dumps the coal onto the shaker in the cross entry. Then the shaker transports the coal into the cars in the strike of' seam. entryJsystem ft. ft. lS-ft. Method.-- of' and-pillar me.t.. hod of' of' of' , ' cut ~achines loaders, ! is" of' 't" hen 14 entries. Room and Pillar Work.- Upon completion of develop­ment work, rooms are driven from strike entries to the rise on 50-80-ft. centers, each room being 18-20-ft. wide. The rooms are driven at an angle of 90 degrees to strike entries In duckbill shaking conveyor sections and at 45 to 60 degrees In mobile loader sections. The latter form sharp corners on two opposite ends of the pillar making pillar extraction quite difficult. The common splitting method of pillar extraction is used. This is quite satisfactory where the roof stands well and conditions are favorable. However, a problem exists under bad roof conditions, especially in those places where the coal seam, becomes thick, where the parting in the seam appears, and finally, where the shale roof is met. Face Preparation.- The face, in driving entries, is prepared in the same order as in the Sunnyside Mine (Fig. 3 ), except that no shearing is done. The undercut is 9-ft. deep, and 14 holes, each 8.5-ft. long, are placed as follows: 5 holes on the bottom row, 4 holes on the center row, and 5 cut, straight. Three to five sticks of permissible sheathed powder is placed in each hole, and stemmed to the collar of the holes Work.-- develop-ment SO-ft. lS-in in seam Preparation.-- 3), ft. 0n \ holes on the top row. The center holes are angled up toward the center, forming a V-cut, and the holes on the rib are ,ermissible holes. 15 The bottom row is fired first, then the middle, and last, the top row. and-pillar is increased.. Haulage.- transportation in the mine is accomplished by a combination of track-and-rope haulage. Loaded 4-ton mine cars are assembled into trips in the strike entries by 7-ton battery type gathering locomotives. They are then hauled to the partings of the First or Second Dip Slopes, where they are transferred to the rope haulage system. These battery locomotives pull 5 loaded cars per trip. Coal from room-and-pillar sections is discharged from conveyors or shuttle cars into the mine cars which are gathered and hauled by locomotives to the Dip Slopes parting. All haulage in slope entries is done with rope haulage. Loaded cars are raised up the slopes and transferred to the Main Haulage parting, and there hauled to the surface by 20-ton trolley locomotives, in 30^car trips. The track on strike entries is laid with 40-lb. rail and on the Main Haulage road with 60-lb. rail. A 40-inch gauge is used. The Castle Gate Mine has a nice haulage system. One especially noteworthy feature is the Main Haulage road which is clean and straight, resulting in quick, efficient fIred Sometimes a top cut is also used if roof conditions are bad. In room-and-pillar areas, drilling is done in the same manner, but as the face is widened, the number of holes increased., Haulage.-- . Transportation and-pillar (" 3t, 30 1b. Hfrulage gaUge \ \ \ transportat ion. Ventilation.- The fresh air Is supplied to the mine by two exhaust fans at the rate of 280,000 GPM. One fan is powered by a 600-hp and the other by a 225-hp motor. In the mine 3-inch of water gauge is obtained. Airtight stoppings and overcasts are constructed in places where needed. Since the mine is known to be gassy, no tubing blower fans are allowed in it; instead lines of brattices, which serve the same purpose, are used. These brattice lines lead the fresh air to within 20-ft. of the advance working faces from the first inby cross-cut. Although these brattice lines are more expensive than the blower fans, they work more efficiently. transporta t Ventilation.-- is CFM. \Jater 16 ft. i ) CHAPTER IV KENILWORTH MINE The Kenilworth Mine is owned by the Independent Coal and Coke Company and is situated at Kenilworth, Utah, 120 miles southeast of Salt Lake City, and about 6 miles east of U.S. Highway No. 6, between Helper and Price. The history ofIthe mine dates back to 1904, but today it is one of the most modern mines in the United States. Kenilworth is, at present, producing about 4,000-4,500 tons of coal in a two-shift day and employing an average of 350 men underground. Seam Characteristics and G-eology.- There are two mineable coal seams in this area. The upper one is being mined, and is called the Kenilworth seam, or the Castle Gate "D" seam. About 150-ft. below this is the Aberdeen seam, which is not being mined at present. These two seams are separated by layers of interbedded sandstone and shale, containing thin layers of coal. The Kenilworth seam is relatively free from rock part­ings and great faults, but local rolls are often encountered across the seam, creating difficulty in maintaining a uniform haulage road. The thickness of the seam ranges^from 9 to 16- ft. The coal is massive in structure and has little evidence of bedding. The rank of coal is bituminous and has a good heating value. The coal bed is free from rock partings, but appear//''1'' of~,the shift Geology.-- liD" ft. seuarated 17 ranges ~t'rom ~/ I ot' at' ( •• \r:', ~' ... in places troublesome rolls sometimes appe'3:~ >,'~".'. ~ ,::' .... ~(t,1, ,\ " ( ,, ,, , , ~. , , 18 The roof is sandstone and forms a good top. The thickness of the cover over the seam ranges from 1,000 tfc 1,800-ft. The bottom is also of sandstone and gives a good road bed. The seam dips about 11 percent toward the nort,h. Mine Layout.-- The mine is entered through an 8,500-ft. long, 7-ft. high and 16-ft. wide rock tunnel, which is driven through sandstone and on a 1.5 percent grade in favor of loads. This tunnel connects with the Main East Entry (main haulage road) at a distance of 8,200- ft. from the portal of the mine. The Main East is driven as a set of triple entries for 3,800-ft. Prom there on it be­comes a four entry system and follows an easterly direction, ap-proaching the strike of the seam for a distance of 10,000-ft. The Main East Entry divides the dip workings from the raise workings. The dip workings consist of slope entries driven downward from Main East and strike entries driven 90 degrees off the slopes at 250-300-ft. intervals. The raise entries are driven upward from Main East, and from these raises again the strike entries are established in the same way as the strike entries in dip workings. The raises and the slopes are driven at right angles to the Main East at from 3,000 to 3,500-ft. intervals. f Because the coal seam dips toward the north, the sets of entries driven south of the Main East Entry and upward are called the raises, and the ones opposite to the raises which t~ ft. ft. ft. EntI'Y hau1age Iftain a set of triple entries for 3,800-ft. From there on it be-comes apnroaching lO,OOO-ft. Bast ft. uDward fr'om X{;ain .t:ast, 8ntries ft. r~ I 1ft r---------~~ ..-... =:t: (j) ... , q-- a-- "" - <;:::, :5 I- --I I.J) :::7) ;;z: '-!) :::, ~ ':t:::. -« .., 2- ........ 0 '0 -t- Q. • ~ lU <{ ~ Z ~~ - - Z l- i:. « ::J ~ CJ ....... <....J >- w <r ~ --J '-../ l.J . ",I) -l.L.. - :a: 0 ... 20 are following down the dip are called the dip slopes. These raises and dips are numbered from west to north, the one farthest west being No. 1, and so on. The headings in dip, raise and strike entries are driven on 75-ft. centers, each being 20-ft. wide. The cross-cuts (slants) and rooms are driven at 35-45 degrees to the entries on 125-150-ft. centers and are 18-ft. wide. In development work, from 0 to a few ft. of top coal is left. That is, where the thickness of coal is less than 9-ft. and the roof behaves fairly good, no top coal is left. Otherwise, up to 5-ft. of top coal is left. Mining Method.- The retreat system of the room-and-pillar method of mining is used in conjunction with a variety of mechanical loading equipment, including track- and crawler-mounted mobile loaders aifl duckbill equipped shaking conveyors. In driving entries either track-mounted units, including a universal cutting machine with electric drill and track-mounted loader, or duckbill shakers with shortwall cutting machines and post-mounted drills are used. In trackless sections uni­versal rubber tired cutter and crawler-mounted loaders are used. These crawler-mounted loaders discharge into shuttle cars • Room-and-Pillar Work.- In room-and-pillar work, pillar blocks, having dimensions not greater than 1,200-ft. by 2,500- ft. are developed by driving the above described strike and ft. l25-l50-ft. lB-Method.-- and­uillar crawler­mounted ardduckbill mounted mounted loader, or duckbill shakers with shortwall cutting machines and post-mounted drills are used. In trackless sections uni­versal rubber tired cutter and crawler-mounted loaders are used. These crawler-mounted loaders discharge into shuttle cars. and-Pillar \Vork.-- and-pillar ft. 21 dip entries. At a point 500-ft. back from the predetermined barrier on the strike entry, a panel haulway is driven down the slope at 45 degrees to the strike entry (See F&g. 6; track shwwn with dotted line). To insure a maximum haulage distance of 500-ft. from the loading station to the discharge end, advance loading stations are installed on either side of the haulage way, and track is laid on the panel line. A hoist is placed on the cross-cut between the second and third upper strike entries. After this has been established, Joy loaders and shuttle cars are employed on both sides of the pan^l line. While the pillar is being pulled on the retreat side, the development work is being advanced on the other side; thus the shuttle car development and the pillar extrac­tion should be simultaneous and kept in sequence at all times. Both sides of each panel should finish together. When pillars are drawn back to the panel haulage a new set-up is made in the next haulage panel and the mining process is repeated. While the present system uses rope haulage on the panel line; a belt transportation system is being considered by the management for the future. The theory of this method of development on retreat work is to produce pillar blocks directly ahead of pillar extrac­tion, thus eliminating the possibility of long standing pil­lars taking weight and bouncing when they are finally disturb­ed. A retreating pillar line (line of break) is developed parallel to the panel haulage, thereby keeping all developed blocks the same distance from the cave line. ft. Fmg. ft. pan~l uil­lars .the 7 A,. 6 - R e .. e.... Wi,. R op. H ""1", g< D" P ... " e/. (["".pe ••• ", C.«I .. C.". Comp"'''!I) I.- - la' ,," ~. ,r- "T " ., ,. 1/. '1 " ,:' 1/ " " .;' II " " 9' " " ~"! .\ I " /I '. " " " I, " " l/ "1 " I. It " " I, "'-lfW I' " " " I'ne. " . " JL \I " - " /, '"' " 1- " • 0 II .. 0 l-r • • • • • ,... 10' • i ~ . • • ...!! .E'-dC E-J/ If. ~ 23 In these pillar blocks, the rooms are driven from the panel lines parallel to the strike entries on 75-ft. centers, each being from 18 to 20-ft. wide. The cross-cuts are driven on 125-150-ft. centers and are 20-ft. wide. The pillars are drawn by the splitting method. In the Kenilworth Mine, the pillars left in room work are diamond shaped. Squared ones were tried in the past, but they result­ed in too high a pressure when mined and tended to slough badly. Now all the pillars left are diamond shaped and have a tendency to release the pressure gradually, resulting in less sloughing while drawing them. Face Preparations.- The if ace preparation is done in the order shown in Fig. 7. The cutting is established with track-mounted and rubber-tired universal cutting-shearing machines. In driving entries and rooms where the face is 10-ft. high and 18-20-ft. wide, an undercut 9-ft. in depth and a shear cut with the same depth and 4 to 5-ft. from the bottom is made. This shearing may be ignored or a full shear may be made, depending upon the conditions present. In pull­ing pillars, for instance, the coal is usually shot on the solid (without cutting). When using under- and shear-cutting, 14 holes are drill­ed, each 8.5-ft. in depth, as shown in Fig. 7. The center holes are angled toward the center, forming V-cuts; the holes on the rib are straight. As the face is widened or the cuts ignored, the number of holes drilled is increased accordingly. heing ft. lef't Preparations.-­the ;face mounted andr.u bber-tired lO-ft. IS-ft. ft. Each hole is loaded with 3-4 sticks of permissible, sheathed powder, and stemmed properly to the collar of the hole. The rows are detonated successively from the bottom up. Haulage * - The transportation at Kenilworth Mine is accomplished by a combination of track-, rope and trackless-haulage, with shuttle cars. Loatdad 4- or 6-ton cars are assembled in strike entries into trips by battery or cable reel type gathering locomotives and hauled to the partings of raises or dip slopes. It the partings these cars are lowered or raised depending upon their location with refer­ence to Main East Entry (main haul way). Coal in shaker territory is loaded into the cars di­rectly by shakers, and in mobile loader sections shuttle cars empty the coal into an elevating conveyor at the load­ing station. The haulage on the Main East Entries is done by 15-ton trolley locomotives. Main haulage distances to the tipple run up to 5 miles. Since the rock tunnel was driven on 1.5 percent grade in favor of loads, the haulage in this section uses gravity instead of power, i.e., the trip is taken outside by the force of gravity and the problem of braking has been solved very cleverly by the use of soft-iron skid shoes placed under the left front wheels of the first four cars. The main haulage line is double tracked, one for empty trips and the other for loaded trips. The track for the loaded trips is 75 lbs., for the empty, 60 lbs., and at the 24 sternmed Haulage.-- trackless­haulage, Loa~3d .At way). l5-"driven Ibs., Ibs., 25 faces, 50 lb. rail, A 42-inch gauge is used and the rails are welded. The haulage system at Kenilworth Mine, as a whole, has been very well planned and a safe smooth system has resulted. Ventilation.- Two centrifugal exhaust fans supply the fresh air to £he mine at a rate of 300,000 CFM. Since the mine is growing and the distances involved are increasing, a new fan installation is being completed. There are five intakes and some of them work with natural ventilation; therefore, a low water gauge in the mine is possible. Airtight permanent stoppings and overcasts are con­structed of concrete, or cinder blocks. Since the mine is classed as gassy, no tubing blower fans are allowed to supply the fresh air to theladvance working faces, but the rubberized type brattice cloth is being used with satisfaction in lead­ing air to within 20-ft. of the working face. rail. sys tem a t I:~enilworth iline, Ventilation.-- ~he theI."- 1:'!ork stoppinss ~nd allov'{ed thejadvance vlith ft. CHAPTER V GENEVA COAL MINE The Geneva Coal Mine, a property of Geneva Steel Com­pany, is a subsidiary of the United States Steel Corporation. It is situated in Horse Canyon, on the eastern rim of Castle VaUley, which is about 35 miles southeast of Price, Utah, and approximately 160 miles southeast of Salt Lake City, Utah. The Initial development of Geneva Coal Mine was begun in 1942, and the Geneva Steel Company began operating in 1943 for the Defense Plant Corporation. On June 16, 1946, Geneva Mine was purchased fromxthe War Assets Administration by the United States Steel Corporation. This mine has a rated- output of 8,500 tons per day, but this quantity of production has as yet not been required. At present, the mine is employing an average of 780 men and pro­ducing 5,000-$,500 tons per double-shift day. All coal is shipped to the Geneva Steel Plant. Seam Characteristics and Geology.- The coal seam being mined at Horse Canyon is the Lower Sunnyside Seam. The Upper Sunnyside Seam, which was described previously, also exists in this district, but is not mined. The coal in both seams is sub-bituminous In rank, and is in the Blackhawk formation of the Mesa Verde group and of UpDer Cretaceous age. The depth of cover ranges from 300 to 2,90C-ft. The roof is of sandstone, shale, and in some places, limestone. The bottom of the seam is a massive sandstone. / VaTIley, salt initial Plarit from, the shift 26 Charaeteristics Geology.-- in f'ormation of' f't. of' shale, and in some places, limestone. The bottom of the seam is a massive sandstone. 27 The Lower Sunnyside Seam, which is being mined, is from 12 to 14-ft. thick. The seam dips about 12.5 percent to the east. The coal seam is relatively free from rock partings, except at the bottom level and in the extreme southeast section of the mine. Since there is no prepara­tion plant on the surface, and sorting underground is im­practical, this rock layer in the coal in places gets thick enough to become troublesome. The coal has no definite cleats or cleavage planes, but has slips which are at 45 degrees to the strike of the seam. The coal has a relatively low (0.8 to 1 percent) sulphur and ash content and has a good coking property. There are numerous faults in this area, both normal and reverse. These faults usually strike east-west. The displace­ments of the faults are usually less than 15-ft. However, there is one fault estimated to have a displacement of 55-ft. Mine Layout.- As mentioned above, the coal seam is highly pitching and faulted. Thus, the layout of the mine is mainly influenced by these two factors. The mine is entered through a rock tunnel originating at the surface, on a dip of 3 percent. The rock tunnel con­nects with the First Level (first set of main strike entries) at a distance of 1300-ft. from the portal. Adjacent and par­allel to this tunnel are a hoist way and a fan entry, driven on level grade. All these entries connect with the First Level. The First Level, which consists of a set of four - unde~ground seam,. to 1 percent) sulphur and ash content and has a good coking displace-ments ft. esnimated ft. Layout.-- f ft. par-allel 28 BA3R2K0E' R ELOPED WITH TRACK"TYPE eomnmrr FIG, 8 - LAYOUT 1* A? ' F SErJE VA C O AL M I N E. \lf/llffHII((\ SANDY SHALC "'"'"'- " \ , ~ I I I I I STRIKE S 24· 21!. : i I /2.71 I t :,, L ,t., \( JUT f'""'.1 ... ~ CO-~ i ~ E. 28 29 entries, runs south to north on the strike of the seam. Prom the First Level entries the raises and dip slopes are driven off at approximately right angles. The First Level is connected with the Second and Third Levels by four sets of dip slope entries. These slope en­tries are on a 12 percent dip and follow the same direction as the rock tunnel. From the Second and the Third Levels, the raises and dips are driven off in the same manner as on the First Level. These raises and dips are connected with cross entries, which are nearly at right angles and are on the strike of the seam. All the entries and slopes are 18-ft. wide and on 80-ft. centers. The cross-entries are also 18-ft. wide, but on 60-ft. centers. The dip slope between the First and Second Levels, and the Second and Third levels is 2,400-ft. long. Mining Method.- The retreat system of room-and-pillar method of mining is employed, together with the use of a vari­ety of mechanical loading equipment. These include track- and crawler-mounted loaders and duckbill equipped shaking conveyors. All main strike and dip entries are driven with track-mounted mobile loaders. This development work usually consists of four parallel, 9 x 18-ft. entries, which are driven on 80- ft. centers. Crosscuts are driven off the main strike and dip entries at every 100-ft. to the right and also to the left, at a 45 degree angle. Crosscuts from the outside entries of each set are turned at 200-ft. intervals and at 45 degree angles, r~ms From 'rhird ft. ft. ft. ft. ft. Method.-- retre~t and-pillar mounted track­mounted develonment ft. lOO-ft. ft. 30 each being 16-ft. wide and 9-ft. high. Shaking conveyors are used chiefly in driving raise and cross entries, rooms, and in pulling pillars. The raise en­tries are driven in 2 and 3 sets, at 600-ft. intervals. The cross entries are perpendicular to the raise entries and at 320-ft. Intervals. The rooms are then driven up the pitch on 60-ft. centers and widened to 25-ft. after 2 or 3 cuts. Crawler-mounted mobile loaders are used mainly in driving through faults and also in room-and-pillar work. In development work the seam is mined to a height of 9-ft,, leaving 5-ft. of top coal. This top coal forms a good roof and is recovered during retreat work with the pillar extractions. Room-and-Pillar Work.- Upon completion of the develop­ment work, rooms are driven UD the pitch on 60-ft. centers and widened to 25-ft., after 2 or 3 cuts. Pairs of rooms are driven from each cross entry in such a way that while one pillar is being extracted from a room, the advance work is carried on in the adjacent room. This provides a roof breakline of 45 degrees to the rooms. While advancing a room, two cuts into the solid are made on 65-ft. centers. Both cuts are taken and 4 props are set in each. The center crosscut of each room is connected through the pillar side for ventilation; the other two are connected during the retreat of the room and pillar. In pillar extraction, the split method is used with duckbill equipped shaking conveyors, as shown in Figure 9. ft. 'rhe en-tries ft. ft. intervals. ft. ft. and-pillar ft., /' and-Pillar Work.-- develop-ment UD ft. ft., nillar for ventilation; the other two are connected during the retreat of the room and pillar. !!1!!W A· --.-.-~- -...-..'. "! £Ir,;.P .I1..I.I._.I.1..II.-. I ....... ~..........i iii: •• . ._ ... ~ 1- =' ..-:.~-.r ... -JII •• !!!!.!II- PI!::!!!! \.!!II _ ... .J-_ iIIIW ......... 1IiJiiF".,J[ iiIi'iiiI • G-= ..... ..,.,......~ ..... ••_ _ jlii~• -•n . .•. r .-&.'Ir.'\.I,. •. • I 1.- r=. trIiIII.' .......... • - D-.-zrm\F~ =-".~~.·In-=-WP..it r· Stf'ltP.~""_ 1- ..,.,.nlJ.llA·U~ I~ !In ~rtII"'W .:.'W ...,.. '· ..r.:.:.. .ar.=.. ..,..... .......: ,i.,...".. .... .. / -- - - --.---- I '5.,\ 11· 1 ,I ·.~r , l ~ IIi :; .>' ~/ 1 ------- ~ I , " II -------.----------~---- ~ t.jO>,'".--~------- ----- .6n - .- ---''''lO /~ ,". . ...,..-.~~ ,. 1 32 The conveyor operation is also fully explained on one side of the same figure. Face Preparation.-- The face preparation in this mine is done in the same order as in the Sunnyside Mine; thus the same Figure (3) is applicable. In all development work, the face is under-cut to a depth of 9-ft. and a center shear is usually cut half-way up the face. This is done both with track-mounted and trackless equipment. The room faces where shakers are used are cut with shortwall cutting machines and drilled with post-mounted electric drills. Drill holes are 8.5-ft., i.e., 6-in. shorter than the cuts, to avoid any possibility of shooting on the solid. Permissible sheathed powder is used, each charge consisting of from 3 to 4 sticks. Each hole is properly st4mmed to the collar. Haulage.- Transportation at Geneva Coal Mine is ac­complished by a combination of belt and chain conveyors and rope and track haulage. The transportation system in use at this mine is an outstanding feature of the operation. In the entries coal is loaded with track-mounted mobile loaders into 8-ton mine cars. Loaded cars are assembled into trips by 10-ton electric gathering locomotives. These trips are taken from an inby assembly station to either of two rotary dump stations at the dip slope (one on the First Level, the other on the Second Level) by 15-ton electric locomotives. All coal mined below the Second Level is hoisted to this Level prepai3ation ft. way mounted drill.ed mounted ft., Haulage.-- snd mounted IO-g~thering 33 by a rope hoist, because the belt does not extend below the Second Level. Coal In room and pillar work is loaded by duckbill equipped shaking conveyor and discharged onto either a chain conveyor or a 36-inch belt conveyor which is instal­led in the main cross entry. In the territories where shuttle cars are used, the coal is loaded by crawler-mounted mobile loaders into 6-ton shuttle cars and transported to an elevating conveyor for discharge onto a 36-inch belt conveyor. The shuttle cars have an elevating discharge head and can therefore empty the coal directly on the belt if necessary. These belt conveyors in the cross entries deliv­er the coal to another 36-inch belt that is installed in the main raise entry. This conveyor discharges the coal into an elevating conveyor car loader. Each car is spotted under the discharge point by a car-spotting hoist. The loaded cars are then taken to the rotary dumps by a 15-ton locomotive. Prom the dump station, a 54-inch belt conveyor trans­ports the coal up the dip, in four lifts, a distance of 2,200- ft., and discharges it into the hopper of the First Level rotary dump. The First belt (lift) is 250-ft. long and on a 15-degree slope, the Second is 643-ft. long and on a 12 percent slope. The remaining two are identical to the second one. The belt from the First Level to the surface (through the rock tunnel) is 1,300-ft. long, 54-in. wide and on a 3 percent slope. It receives coal from both rotary dumps, and delivers this to the transfer house on the surface. This in nillar mounted an elevating conveyor for discharge onto a 36-inch belt conveyor. The shuttle cars have an elevating discharge head and can therefore empty the coal directly on the belt if necessary. These belt conveyors in the cross entries deliv­er the coal to another 36-inch belt that is installed in the main raise entry. This conveyor discharges the coal into an elevating conveyor car loader. Bach car is spotted under the discharge point by a car-spotting hoist. The loaded cars are then taken to the rotary dumps by a 15-ton locomotive. From hopner rotary dump. The First belt (lift) is 250-ft. long and on a ft. slope. The remaining two are identical to the second one. turmel) ft. "vide 34 coal is discharged onto a 48-Inch belt conveyor, 3,300-ft. long, which then takes the coal to the tipple through a conveyor gallery. The man trips and the supplies are transported through the main Third South portal to a rope terminal at the main slope. There they are lowered to any parting along the hoistway. Ventilation.- Two Jeffrey Aerodyne exhaust fans supply the fresh air to the mine at a rate of 350,000 CPM. The north fan exhausts the openings north of the main hoist slopes at a rate of 150,000 CPM against a 2.7 inches water gauge. The south fan exhausts the districts south of the main slopes at a rate of 200,000 CPM against a water gauge of 1.6 inche s• The mine is classed as non-gassy, so that auxiliary blower fans can be used to supply fresh air to within 20-ft. of the advance working faces. These tubing-blower fans are used only in track-mounted mobile loader districts. In shaker territories brattice lines are preferred. All mined out areas are sealed off with fire seals. Overcasts are constructed of cinder blocks and reinforced concrete. Temporary stoppings are of metal lathe and plaster, supported by 1-in. board. The permanent stoppings are of cinder blocks and plastered with cement. inch ft. triDs sloDe. Venti1ation.-- CFM. CFM ,,'later distr'icts CFM inches. eO-ft. mounted I-cinder blocks and plastered with cement. CHAPTER VI D. 0. The D. 0. Clark Mine, a property of the Union Pacific Coal Company, is located at Superior, Wyoming, about 15 miles north of U.S. Highway No. 50. At present most of the tonnage comes from shaking conveyors. The mine is producing 4,000 tons of coal in a two-shift day, from 4 seams, and employs an average of 500 men underground. Seam Characteristics and Geology.- There are four mineable seams in this area. Under 600-ft. of sandstone and shale cover, the coal seams are separated by inter-bedded layers of black shale and sandstone in the order shown in Figure 12. They occur in the northeastern rim of the Baxter Basin. The coal is of bituminous rank and Cretaceous age. The seams dip 4 degrees to the west and range in thickness from 4 to 14-ft. There are no faults of great importance. The roof is of black shale and sandstone, and varies In strength as the composition changes; the higher the shale content, the weaker the roof. The coal itself is quite friable. In development work from 1.5 to 4-ft. of top coal is left. At present, the mine is non-gassy. Some Impurities like sulphur and pyrites are present in the seam. O. CLARK MINE o. u.s. 30. shift Geo1ogy.-- ft. inter­bedded ft. in impurities 35 3 * FI6. 10 - T H E PA CI FJC COA L CO. - D. 0. C LARK MINF NO, 7 SB A M. MINE LAY^aT. (Courtesy Of £/i'«fl PaiCifr'c Coa.1 C o m p c c n L j) r­I ,I F16. 10 -THE. UNION PACIFIC [OAL {O.-D.O.CLARKrvllNFNO.7 SEAM. M1NE LAY0t1T. Mine Layout.- The mine is entered through two slopes. In one a belt conveyor is installed for hauling the coal, in the other rope haulage is used for handling material and transporting the men. These slopes are driven on 50-ft. centers and 18 percent dip. A 48-in. wide and 2,500-ft. long belt serves four seams at the same time. There is a turnout station for each seam where the slope cuts them. At every turnout there is a rotary dump for transferring the coal from the mine cars to the belt conveyor. The belt then takes the coal to the tipple which is located on the surface. Prom the turnout station on No. 7 seam, two entries (one a motor road, the other for air return) are driven near­ly on the strike of the seam, in favor of the load. These entries lead to the Main North, No. 1 Dip Slope, and No. 2 Dip Slope. The No. 1 Dip Slope is driven down the dip of the seam at approximately right angles to the Main North entries. About 4,000-ft. beyond the No. 1 Dip Slope is the No. 2 Dip Slope driven parallel to it. These slopes and the Main North consist of four sets of entries which are driven on 70-ft. centers. The strike entries are driven at approxi­mately right angles to the dip slopes and at 300-ft. intervals. These strike entries are a two entry system. Mining Method.- The room-and-pillar method of mining has. been adopted with the use of duckbill shaking conveyors and mobile loaders. These include the shortwall cutting machines and the Chicago "Little Giant" drills. Layout.-- ft. ft. From near­lyon I 4,OOO-ft. 37 ft. ft. Method.-- and-pillar I1Little F\&. U _ 3HDW\m METHOD OF EXTRACTING ROOM AND ENTRY PlLLAKS W/TH DUCKBILL-SHAKING CONV£WK. I / . COAL CO. MINES AT POCK SPRIN&5^ WOKING _ . . (Court e.±y Qf Union PAC'LUC Ce«J ComBmjijfJ 00 BLOC". i '--_._------ -- MAP C A v [ D / ./ / / 0 ARE 0 , ()~ ~ .... IU~ {6: 'i lie Q • I •• ~fAKfR ~O .. ~TART£D AS ;Z'IPROT!(TIDt/ /1'1 CA5fQVICII : 0 ., MOV~ NfCfSSA/lY o -"N6"'Z o.-. • :z ~ ... <IL. ~3 i .. FiG. fI _ SHDWiNG METHIJ/J CF EXTRACTiNG ROOI", AND ENTRY PiLLAR5 WiTH DUCKBiLL-SHAK'ING CONVEYOR. U. P COAL CO. MiNES AT POCK SPRiNGS., WYOMiNG .________ (CourtesJ Qf 1J.II.;~n P~ci.fl.C-._J.:IL~LCo.rne.<&JI!J)_ 3 9 600 rr. or coven 6 FT COAL SI AM \mo FT. BLACK SHALI •1-/4 ft. COAL 150 FT. B L. SH. 7 FT. COAL too FT. Bl. SH. 7 p r . COAL BOTTOM 5HALE FI6.1Z SHOWS THE CROSS SECTION OF SEAMS D. O. C L A R K M I N E . •SHAKING CONV. •SHUTTLE CAP ! Me0 /,Ck- 1 I 1 I \ ! ! TRACK M A N W 4 Y (3- SHAKER 4- SHUTTLE. N P A N E L - W O R K. 600,r. !'), cov,,~ 'For C()A~ 'HAM ..,-14 ~r. COAL 150 Fr. 8L. SH. 7 FT. COAL 100 Fr. 8t.. SH. 7 ~ r. rDAL p,OTTOr"l .sHALE FIG.12 $£C TION 5EAMS OF D.O. CLARK MINE. r-----------------. --.--. - . --_ .. ------ --~ '---'1 I . _____ .. _ I i. T j'v'1. A i'1-1'/ A Y ('.:.:~~- '-'-' -, TRACK: .HAUL ',,;.:.y FIG. 13_ 4- SHf)TT LE. CAR r-J PAN E/; WOR J<... 39 The mine was developed with the shaking conveypass only, but recently, the company has put two shuttle cars (cable reel type) in combination with 14 BU Joy loaders for panel work. The working system of shuttle cars in panels is il­lustrated in Figure 13; the Joy loads the shuttle car at the working face which then dumps the coal onto the shaker in the cross entry. Then the shaker discharges the coal in­to the mine cars in the haulageway. The rooms are driven at angle of 90 degrees to the strike entries on 55-ft. centers. The maximum depth of the rooms is 300-ft. and width is 24-ft. Pillar Extraction.- The pocket-and-stump system of mining pillars Is employed. Figure 11 illustrates the pillar extractions wlth_iduckbill shakers in rooms and entries. As shoY/n in the key map of the same figure, a break line that makes a 45 degree angle with the direction of retreat is maintained. This whole system has been standardized by the Union Pacific Coal Company and is used by all mines that are operated by them. The distinguishing feature in this method is that while one pillar is being mined on retreat, an adja­cent room is being advanced. In extracting the blocks of pillars, 18 to 20-ft. wide 6 to 7-ft. long cuts are taken in the order shown in Fig. 11. A sacrifice pillar is l£ft on the caved area side. It is weakened enough to crush out after timbers are pulled. Before taking the timbers from the mined block, the breaker row timbers are installed near unmined block to limit the cave 40 conve¥pDs . ft. ft. ft. Extraction.-- is with~duckbill shown Same rrethod b locks ft. vdde s~own is l~ft unnined IIII iM« ll ll ll 11 II il ll II i» ii 1' ' ! « 115 H lie ii n ii n i« 'i l! 1. TOP iQ O T 9 4 ^-SHEAR CUT , 3 7 2 4 FT. F I G . / f - D R I L L I N G PLAN . NUMBERS OE NOTE ORDER SHOOTING. D.O. C L A R K MI/YE. I,II -- - II - -II -- " - - - II -, II II I' " 'I I " I' Iii II II II /I II II I II II I' " " 11 II I' "I ,"I I" I II II " I' " '1\ II~ ", II II I' II 1/ II, " I~ I'''' ,,3 ,,7 I" II tI II II ,I II II II II ,I I ,'9 \1 'I " ,I II! " " ,I " , I .. ,. r TOP ......C. ClT _-;SHEAR \ , '..t. 5 2- I) I 5' I \ ~ .' ..n ! ~' , 5 t 5' 8 " " , , 1 .' ~ -- -~ 5 :J .. • .0 ---- ~ 2.'t F T. -.~------------4t'l IG.11- DRILLING PLA N. NUMBERS DE NOT [ ORDER OF SHOOTrNG. CLARK MINE. 42 along the desired line. Up to 60 percent of the timbers are recovered and reused for further supporting. Face Preparation.-- The face is prepared in the order indicated in Figure 14. 'Both top cutting and shear­ing are employed. Top cutting is done at or near the top of the seam, leaving enough top coal to help support the roof. Shearing is done in the center of the face to re­lieve the coal burden and to make the blasting easier. The depth of cutting and shearing is from 8 to 9-ft. For this purpose, the rubber tired shortwall cutting machines are used. Beside the cuts, 9 holes are drilled at the face with a Chicago "Little Giant" drill and McLaughlin augers using re­movable bits. The depth of the holes are 8-J-ft. They are loaded with permissible sheathed explosives and are tamped to the collar with dummies of incombustible material. One hole is shot at a time, followed in the sequence indicated in Figure 14. All holes §re drilled normal to the face. Haulage»- Transportation of coal at the D.O. Clark Mine, No. 7 seam, Is accomplished by a combination of track haulage and belt conveyor. For transporting the men and the material, rope haulage is used on the Main Entry Slope. Loaded 4-ton mine cars are assembled Into trips in the strike entries by 15-ton trolley locomotives. These locomo­tives can pull from 24 to 30 loaded cars je r trip to the rotary,dump station at the slope. The belt takes the coal Both shear-ing s,upport re- lieve ft. pur-pose, Li ttle Giant II IilcLaughlin 8~-ft. dWT'111ies in::iicated %re Haulage.-- rHne, is accomDlished t:c'ack into Fr trip to rotary_dump 43 directly to the tipple. In shaker territories, the coal is loaded from convey­ors into the cars on the haulways. In mobile loader sections, the shuttle cars dump the coal onto shakers and then the shaker delivers it to the cars in the haulway. Ventilation.- Each one of the four seams are venti­lated individually by separate fans. The fresh air for the No. 7 seam is supplied by a 50 hp fan, at the rate of 120,000 CFM against a 2-inch water gauge. Ventilation In room work or beyond the farthest cross­cuts is maintained with an auxiliary blower fan (2 hp). The tubing of the fan is kept within 20-ft. of the working faces at all times. itro Ventilation.-- seDarate f'resh f'or f'an, in .fan hpJ. f'an ft. 44 CHAPTER VII STANSBURY MINE SEAM NO. 1 The Stansbury Mine, a property of the Union Pacific Coal Company, is situated 7 miles north and 2 miles east of Rock Springs, Wyoming. This mine was developed during the war for the purpose of meeting the increased demands of the Union Pacific Railroad for fuel. The Stansbury Mine is, at present, producing 4,000 tons a day from three seams. The mine is largely in the development stage. Seam Characteristics and Geology.- There are three seams in this area that are separated with interbedded layers of sandy shale. The thickness of these layers vary from 135 to 150-ft. The coal is bituminous in rank, and of Cretaceous age. The seams dip 9 percent to the east, and range in thickness from 5 to 17-ft. There are no faults of great importance. The roof is of sandy shale, sandstone, or limestone. The coal itself is friable; cleats and cleavages are well pronounced. In the No. 1 Seam, there Is a rock parting from 1 to 2-ft. in thick­ness, which contaminates the coal mined. In places where the coal is too high, or the roof is too weak, up to 5-ft. of top coal is left in order to keep the entries at a desirable height or to -protect the men against roof falls. CHAP'rER VIr Paci:fic :fOI"' Geology.-- ft. ft. 'well is coal is too 'high, or the roof is too weak, up to 5-ft. of top coal is left in order to keep the entries at a desirable 45 Mine Layout,- The mine is entered through a rock tunnel which is driven against the pitch of the seams on a level grade. This tunnel intersects the No. 3 Seam (first upper seam) at a point 2,300-ft. from the portal, the No. 1 Seam (second upper seam) at 3,050-ft., and the No. 7-J Seam at 3,800-ft. from the portal (See Pig. 15). At the point where the rock tunnel hits the No. 1 Seam the Dip Slope Is driven-down the dip. This dip slope leads to the Main Haulage road and further down to the entries which are driven on strike. The Dip Slope is a single entry until it hits the Main Haulage road. Then it is driven as a four entry system. The slopes are on 55-ft. centers, each being 12-ft. wide. The Main Haulage and other strike entries are driven at right angles to the slope and are on 50-ft. centers, being 14-ft. wide. Sub-slopes are driven parallel to the Bip Slope at approximately 300-ft. intervals. Mining Method.- The retreat system of room and pillar method of mining is accomplished with the use of duckbill equipped shaking conveyors and mobile loaders. In the develop­ment work In coal all downgrade places were driven with track-mounted universal type cutting machines and Joy loaders, up­grade places with shortwall cutting machine and shaking con­veyors. The strike entries are driven with shaking conveyor units. Prom these entries the rooms are started in pairs to the rise. Pillar extraction is followed from the end of the entries toward the Dip Slope. The major portion of the mining Layout.-- ft. ft.,and 7~ ft. Fig. 15). is driven ent~±es ft. ft. .ft. l4-nip ft. Method.-~ in track­mounted From 47 equipment consists of shaking conveyor units, together with shortwall mining machines and electric drills of hand hold or post mounted type. The pillar extraction system and timbering is just the same as described before in D. 0. Clark Mine. These and other similar operations are standardized by the Union Pacific Coal Company. Face Preparation.- The face is prepared in the man­ner shown in Figure 16. It is undercut Mfeh a cutting machine to a depth of 9-ft.- Above the undercut 9 holes, 4 in the center row and 5 on top row are drilled to a depth of 8.5-ft. The holes are loaded with 3-4 sticks of permissible, sheathed powder, and are tamped to the collar with the dummies. One hole is shot at a time, in the order shown in Figure 16. All holes are drilled normal to the face. Haulage.- Transportation in Stansbury Mine is accomp­lished by a combination of track- and rope-haulage. Mine cars of 4-ton capacity are loaded in the strike entries directly from the shakers or shuttle cars. These loaded cars are gathered by electric locomotives and are hauled to the slope partings. Then they are hoisted up to the rock tunnel partings. In the sub-slope sections, the cars are gathered in the same manner and hoisted up to the Main Haulage road partings. They are transported from there along the Main Haulage Road to the Dip Slope. From the top of the Dip Slope the trips are o. Preparation.-- shovm Wfhh ft., dr~lled shovm dtilled Haulage.-- Transportaj;ion 48 Fi9.i6-I>rHliK3 Pl+nln s f a n s k ^ y Mine . Number* Denote Order Of Skooti'ng. u- 1 II / ' I II// , 4 // ll // 'I i*1 UNOCRCUT VIEW fACJL V/ E W Fi«j-/0- Dri/'/n^ P/a.w In Re//ounce Mine - N u m b e r D e w o fe OrJ*r of Shootin^- ~- ------- 14 I ----------~ o 8 ..., o 7 .. o 5 o 6 o 9 J o , '0 _F~\:E _"-LE.. 'If!. ----- --~::.=---------------I Fi9.IG-OrUIi"j PI.nllt s ta.nsl>ut Y MlfIC. Numbe"'5 Denote Ottler Shooting. I( ~\\ iII i - - -1I1I - - -"II, ;I'1 I 1 I oJl II )/rII I I, TOP I~ 11 ItI' I "- VJFW /I ~ ~ II II il ' 11 ~ II " II I. II ~ 2- II ~ 1/7 IIII "' II \ :, ,I rI - " \ Lt. IIII 'i ~---- /1' ~ ~5 .~3 ~~ T , " == ===.~-.. oI .-=-=.':.~== "0 £ACl._ 1 _~w (UIIOER CfI T Fi,.'B- f).jllin!j PIIII..If In R./ia.ftce M;"e. Numbcr.s Denote Ott/at- Of Shoot;n,. 48 49 taken through the rock tunnel. The main line haulage is accomplished by the use of 13-ton trolley locomotives. Ventilation,- The fresh air is supplied to the mine by two Aerodyne fans that exhaust at a r|te of 100,000 cubic ft. of air per minute. The fans are powered by 25 hp motors and operate at a 1-inch water gauge. The permanent stoppings and overcasts , are airtight and are constructed of concrete. At present the gas per­centage is not too £$igh. Ventilation in room work or beyond the farthest crosscuts Is maintained with an auxiliary, blower fan and the tubing is kept within 20-ft. of the face. Ventilation.-- w~ne r~te I-are airtight construc'ted ~gh. is 50 CHAPTER VIII RELIANCE MINE NO. 11 SEAM The Reliance Mine of the Union Pacific Coal Company is situated 5. miles north and 6 miles west of Rock Springs, Wyoming. U.S. Highway No. 187 passes about 4 miles west of the town of Reliance. The No. 11 seam of the mine employs 220 men under­ground, and produces about 2,100 tons of coal per day on a two-shift basis. Seam Characteristics and Geology.- In the Baxter Basin the Reliance Mine recovers a coal bed 7-ft. thick, which is known as No. 11 Seam. About 125 ft. above this Is the Reliance No. 7 Seam, which is also being mined by the same company. The interbedded layer between the two seams consists of sandstone and sandy shale. The upper seam (No. 7) is being retreated ahead of No. 11 Seam. The coal in this area is of bituminous rank, and of Cretaceous age. The seam dips as much as 16J- percent to the west. The strata above the seam consists of sandy shale and forms a weak roof. The bottom is the same. There is a 18-in. thick rock parting in the seam about 18-in above the bottom. It is usually left as part of the floor, but where the coal seam gets thinner this parting is mined to get enough clearance-. Although the seam is only 7-ft. thick, from 1 to 1.5-ft. of top coal is left indevelopment work for protection 5 miles north and 6 miles west of Rock Springs, shift Geology.-- 7-:ft. know"n is of and sandy shale. The upper No. 11 o:f .of 16! la-clearance. ft. in development :for 51 against roof falls. Because of the bad roof conditions, close timbering is used. The rate of gas liberation Is low and therefore the mine is classed as non-gassy. Mine Layout.- From the surface, a rock tunnel is driven against the pitch of the seam on a level grade. This intersects the No. 11 Seam at a point 2,200,-ft. from the portal. In order to intersect the seam at two points, the rock tunnel splits (Y-shaped) at a 100-ft. distance from the seam. This is done to obtain convenient haulage; i.e., the trips from the north and south side of the mainline enter into the tunnel separately (See Figure 17). The Main Haulage Road runs in a north-south direction and consists of four entries. These are driven on 50-ft. centers and are 12-ft. wide. From the mainline, four sets of slope entries are driven down the dip of the seam at 3,800-ft. intervals and on 50-ft. centers. These are 12-ft. wide* The hoists are installed up above the main line part­ings for the rope haulage. The strike entries (double entry system) are driven at approximately right angles to the slopes at 300-ft, intervals. Mining•Methods«- The retreat system of room-and-pillar method of mining is accomplished with the use of duckbill equipped shaking conveyors and mobile loaders. In the is Layout.-- Serun 2,200~ft. lOO-ft. 17). ft. l2-ft. ft. l2-vlide. system) are driven at approximately right angles to the slopes at 300-ft. intervals. Mining. Methods.-- and-pillar sail i? • • - h p ! 5-2 "•"sass 53 development work in coal all downgrade places are driven with track-mounted universal cutting machines and Joy load­ers; upgrade places with shaking conveyors and shortwall cutting machines. The major piece of mining equipment is the shaking conveyor. The strike entries are driven by a pair of shaking conveyor units. They are then turned on the pitch line for room-and-pillar extractions* Because this mine is also operated by the Union Pacific Goal Company, the same standardized system for pillar, extrac­tion is employed (See Fig. 11). Face Pre parat ion.- On a 6-ft. high and 14-ft. wide face, a 7-ft. undercut is made with a shortwall cutting machine. About 5 holes are drilled with a Chicago " Little Giant" drill and McLaughlin auger, using removable bits, to a depth of 6.5-ft. The number of the drill holes is increased with the size Of the face. The holes are charged with permis­sible sheathed powders, and tamped to the collar with dummies. One hole is shot at a time in the order shown in Figure 18. Haulage.- Mine cars of 4-ton capacity are loaded in the strike entries directly from the shakers. These are gathered by 8-ton locomotives and hauled to the partings of the dip slopes. Then they are hoisted up to the top end of the slope and lowered to the mainline partings. These cars are hauled to the surface through the rock tunnel by 15-ton trolley locomotives. mounted load­ ·ers; roan-pillar extractions. Coal pillar.extrac­tion 11). Preparation.-- Chicago" denth of Haulage.-- 54 The track on the main haulways is laid with 80-lb, rails. The secondary track in strike entries and slopes is of 60-lb. rails. The tracks are on a 42-in. gauge. Ventilation.- Two exhaust fans which are located on top of the air shafts supply the fresh air to the mine. i¥hile one fan on the first dip side exhausts the air from the first dip section, the other fan on the second dip side exhausts the air from that particular section. In this way the ventilation is well balanced in the mine. Permanent stoppings and overcasts are airtight and are constructed of concrete. Brattice curtains are used temporarily on the crosscuts. Ventilation in room work or blower fans. haul ways lb. Ventilation.-- eNhaust While beyond the farthest crosscuts is maintained with auxiliary 55 CHAPTER IMPERIAL MINE The Imperial Mine is owned by the Imperial Coal Com­pany, It is located about three miles east of Erie, Weld County, Colorado, about 28 miles north of Denver, Colorado. Highway 185 passes a quarter of a mile to the east of the mine. Seam Characteristics and Geology.- In the Denver Basin, the Imperial Mine recovers a lignite seam known as the L?ramie Formation. The coal seam lies under a cover of 280-ft. which is composed of slate and soapstone. This forms a weak and tender roof which calls for narrow openings and good supports. Faults, if any±: are not of great impor­tance. The bottom is of soapstone and sandstone, with the main bottom of sandstone. The thickness of seam varies from 6 to 10-ft. Some 18-in. of coal over a natural parting is left to protect the top. The coal seam dips about 1 to 1.5 percent to southeast. Coal, in this mine, m^r be said to be free from impurities. Mine Layout. For mine layout see Figure 19. The mine is entered through a. double compartment, 283-ft. hoist shaft, which is driven from the surface down to the bottom C1Ll\.PTER IX :Com­pany. The mine produces about 800 tons of coal per day, and employs an average of 80 men underground. All tonnages come from shaking conveyors. Geology.-- the Lpramie f't. soapst.one. any¥. liopor­tance. f't. mcy MiI),e Layout.-_. a double compartment, 283-hoist FIG. - SHOWING THE WINE Of Ml NF OP I IMPERIAL CO. A T ERlE3 VJELb QCuHTyj COLO. (Covrt&syof Imperial Coal Ccmpan^J ~. , i . L ' AIR SHUT -"--_ .. - I ------~ .. _._--_.-.. --------- I . ,I ! ---------) Ff6. 19 - ':POWING TH[ MINE LAYOUT or IMPERIAL MINf or:. IMPEklAL COAL CD. AT ERI£~ WcLlJ (fJuNTY; COLO. (Courtesy 01 Impericz. 1 Coal [cmpun!J) 57 of the coal seam* This shaft serves for hoisting men, material, and coal. Prom the hoisting shaft, the main north and south entries are driven on 50-ft. centers and are 10 to 11-ft. wide. The mine, as a whole, is a double entry system, including the side entries. At approximate­ly a 90 degree angle to these north and south main entries, east and west entries are driven* Extending from these are north and south cross entries. All entries in the mine are from 10 to 11-ft. Y/ide and are on 50-ft. centers. The cross­cuts also are from 10 to 11-ft. wide, but they are driven on 60-ft. centers. Mining Method.- The room-and-pillar system of mining is successfully employed. Care in the early stages of mining is reflected in the straight entries and very regular panel development. By about 1937, the room-and-pillar work in the panels was well developed, leaving some virgin coal in the barriers. The latter contained appreciable amounts of coal and were economically mineable. So the shaking conveyors were started in the barriers as well as in the room Yrork. At present, all tonnages come from shaking conveyors. In the mine 14 shakers are employed. These are equipped with a 6-ft. long and 30-In. wide pan. After the face is undercut, the pan is placed under the coal to YYithin 6-in. of the back of the undercut, and then, the center is shot dov/n on it. In this way, the conveyor can shake out the coal with a minimum seam. From ft. Il-approximate- ly driven. wide ft. II-ft. Method.-- and-pillar develonment. room~and-pi1Iar developed; lattercon\Uned and were economically mineable. So the shaking conveyors were started in the barriers as well as in the room vvork. in. within then. dovm way; ·SB L FIG.tO 3H0W5 TIMBERING AND ROOM aJORK IHPEMAl A A I N E. FI6. 2 / - PILLAR P U L L I N G W I T H SHAKER AT l M P E R I A I M INF. 58 • .. • • ., ~ .. 0 · I .. '" .•. • • 0 '" • 0 FOST 0 (> TfJBINC ------------------- -------.-- -" , __ . ____ "_ .. _.. _ _ ,1 r/G.czo ~HOW5 TIMBERING RQol'/) A/OP K IMPE~'AL /V\INE. -+----------------------,----- ---- ._-'- ! (. .0.({{ (( { DOUBL[ ROW ¢ '. 0 BREAKER P05TS ,'Q ~<v . 'X"", c ~- " / / " CJ /~ 0 _// f) 0 . <> 0 0 " 0 5HAKE.~ DRIVF----h-..-' .------------_ .. _-- ~--! FIG.21- PILLAR PULLING WITH ~,HAKE,R, AT IMPERIA! MIN,c, 59 Face Preparation.-- With a shortwall cutting machine requirement of hand shoveling. Upon, completion of the panels, break entries are driven off at 90 degree angles to the cross entries. Prom each side of the break entries, the rooms are driven off at right angles. The rooms are 200-ft. In depth and are on 23-50-ft. centers. In the. panels, 140-ft. barrier pillars are left to be mined afterwards. For protection against spontaneous combustion, a 20-ft. pillar is left permanently between the bottom ends of the rooms. This prevents the air from circulating through the goaf after the pilh rs are removed. For Illustration, see Figure 19. For pillar extraction the "open-end" system with the use of shaking conveyors has proved efficient and safe. The recovery, including barrier extraction, is as high as 92 percent. In room and pillar work, double sets of timbers are placed, starting from the room neck and running to the end of the room (See Figure 20). While drawing pillars (Fig. 21) at the end of the room a breaker row of timber is set to cut off the cave. Barrier Extraction.- After room and pillar work is completed, the barrier pillars are extracted. Figure 22 il­lustrates the complete extraction of the barrier on one side of an entry and the partial extraction on the other. This leaves a fire pillar. Upon ere From etlch l'ooms ft. in 30-ft. f't. ft. the rooms. This prevents the air from circulating through the goaf after the pilBrs are removed. For illustration, 'with Vlork, Extraction.-- Preparation.-~ F/6.22 BARR/ER RECOl/fRHN IMPFRJAi. MINE .RMT IS &EING COMPLETEIY LFFT PARTLY RFMOVf 0,LF/W-W£ F/flf PILLAR. (COAL AGE . OCTOBB H -} 13 H € ) . u . . r ; 0 5 (to -Z o FT. UNDER C( / r 6 DFfP f o FIG.25- SHOWS THE FAC£ PREPARATION AT / M P f R ML mine ~, , .' ~-' . F/G.~2 - SHOWING BARRIER RECOVERY IN lMPfRJAL MINE. RIGHT 15 Bf/NG COMPUTEIY REMOVED. LEFT PARTLY RcMOVEDJLEAV- .;;. ING A FIRE PillAR.. (COAL AGE. OCTDBE R. -, 19 ~ 6 ). /,-VND£ R C()r 6' DEEP -- F"IG.Z5- FACE PREFARATlON AT IMPERIAL MINE 61 a 6-ft. undercut is made (Pig. 23). The holes are drilled normal to the face for blasting with the permissible explo­sives. When cardox tubes are used, the top holes are dropped a little and angled up. Drilling is done with auger type, portable drilling machines. Two kinds of charges are being used, permissible explo­sives and cardox tubes. The latter is used only when large lump coal is desired. In using permissibles. each hole is charged with 3 sticks of powder and is tamped to the collar with dummies. Haulage.- Mine cars of 1.5-ton capacity are loaded in the cross entries from the shakers. These are then gathered by 6-ton battery locomotives and delivered to 8-ton trolleys on the mainline. The loaded trips are hauled to the shaft station and empties brought back. The transportation in this mine Is accomplished by a combination of track-haulage and shaft hoisting. The natural conditions of the seam make it possible to have smooth running transportation system. Ventilation.- One fan at the surface supplies fresh air to the mine at the rate of 100,000 CPM. There is another fan next to this for emergency purposes. This has a capacity of 70,000 CPM. In the mine an average of 1.5-in. water gauge is obtained. Auxiliary blower fans are used to maintain the fresh air Fig. type; explo~ sives permissibles, Haulage.-- is Ventilation.-- CFM. CFM. Auxillary In room work or beyond the farthest crosscuts. The tubing is kept within 20-ft. of the face. in ft. face • ..... ; 62 63 3N IN 3l9V3 .: J,jy,i InOt\Yl -v2 "91J 64 CHAPTER X EAGLE Mim Adjacent to the Imperial Mine and to the south is the Eagle Mine, which Is also owned and operated by the Imperial Coal Company. The Eagle Mine is, at present, producing about 1,600 tons of coal in a two-shift day and employing an average of 110 men underground. Seam Characteristics and Geology.- The Eagle Mine is also in the Denver Basin and mines the lignite coal seam of the Laramie Formation. The average cover is about 370-ft. and consists of sandstone and shale. This forms a rather weak roof especially where the shale content is high. The seam is flat and ranges from 7 to 10-ft. in thick­ness. The coal is not overly friable. About 2-ft. of top coal is left in development work where the thickness of coal is great enough to provide sufficient clearance; otherwise the top coal is ignored. There are no faults in the area of any importance. The seam itself is clean; and free from rock partings and Impurities. Mine layout.- The Eagle Mine is entered through a double compartment, vertical shaft. The depth of shaft from surface to the bottom of feeam is 369-ft. This shaft serves to hoist men, coal and material. From the shaft station, the EAGL};~ MINE .lmperial is shift Geology.-- ft. shalte ft. SUfficient impurities. Layout. -- thro ugh seam ft. Main Forth and Main West entries are driven. North and west entries are driven off the Main entries at right angles forming blocks of panels. In these panels cross entries branch off the above north and west entries at 300-ft. inter­vals. They are about 1,100-1,200-ft. long, leaving a 200-ft. barrier (See Pig. 24). Prom these crcs s entries the rooms are driven off at right angles and on 40-ft. centers, each room being 12-ft. wide and 250-ft. long. The slants (crosscuts) are on 60-ft. centers and are also 12-ft. wide. The whole mine is a three entry system (except some of the cross entries). All entries are on 50-ft. centers and are 10-ft. wide. Mining Method.- In the Eagle Mine the retreat system of room-and-pillar method is accomplished with the use of trackless mobile loaders and shaking conveyors. The mine was originally developed with shakers alone, but today these have been totally replaced by trackless mobile loaders. The new equipment includes 14 BU Joy loaders, shuttle cars, 7B Sullivan cutting machines, and portable auger drill machines. All of this equipment is powered by permissible cable reel. Room and Pillar Work.- Upon completion of development work, the rooms are driven perpendicularly off the cross entries to a maximum depth of 250-ft. The rooms are 12-ft. wide and on 40-ft. centers. The rooms in this rrine a^e 6!? North ft. 1,lOO-1,200-ft. ft. Fig. 24). From crCB ft. ft. ft. 50-ft. ft. ft. lO-:Mining Method.-- and-pillar ~rmissible Work.-- perDendicularly off' ft. l2-ft. are 66 narrower than those in the Imperial Mine and need no timber­ing during development work. Two sets of timbers are set In the rooms while pillars are being extracted, and a breaker row is placed to cut off the cave. The pillars are pulled in the same manner as in the Imperial Mine, which was described previously. The only difference between these two is that in this mine mobile loaders are used instead of shaking conveyors. At present the barrier pillars are not being extracted. Face Preparation.- For an illustration of face preparation, Fig. 18 can be used. On a 12-ft. wide and 8-ft. high face three top and two center holes are placed. The undercut is 8-ft. deep and the holes are 1/2-ft. shorter than the undercut. The top holes are straight, but the center holes are angled up toward the center of the face when cardox is used. For blasting with powder, all of the holes are drilled straight. After the undercut is completed and the holes are drilled, it is shot either by cardox or by permissible sheathed powder. When powder is used, the holes are charged with 2-3 sticks and tamped to the collar Y/Ith dummies. Haulage.- Transportation is accomplished by track-haulage and shaft hoisting. The cars are loaded by shuttle cars In the cross entries and gathered by small trolley lo­comotives which deliver them to the main entries. The trips in Preparation.-- ft. ft. permisSible Vifhen pO'wder with duramies. Haulage.-- track­haulage in h¥ 6? from the main entries are hauled to the shaft station part­ings by 10-ton trolley locomotives. They are then hoisted up to the surface. A double compartment shaft is used, and while the loaded car is hoisted in one compartment, the empty car is lowered in the other. The tracks are laid on 36-in. gauge, and the cars are of 2-ton capacity. All of the locomotives, ranging from 4 to 10-ton, are of the trolley type. Ventilation.- Fresh air is supplied to the mine by an exhaust fan at the rate of 116,100 CPM.through the shaft. There is another fan adjacent to this one for emergencies. The main fan is powered by a 40-hp motor and maintains a pressure of about 1.-5-in. water gauge. Ventilation in rooms or beyond the farthest crosscut is maintained with an auxiliary blower fan. The tubing of the fan is being kept within 20-ft. of the face. The mine is non-gassy. part-ings IO-d.ouble other • . tI'acks capacity_ Ventilation.-- CFM ~hrough preS2ure l.~-in. auxiliar~T ft. 'Jlhe gassy_ 6'fl PART TWO: COMPARISONS 'rwo: 68 CHAPTER XI CRITERIA OP COMPARISON Before comparing the various types of mining methods that have been studied previously, let us define what is meant by the best one. The best mining method is the one which is the safest and most economical with the highest recovery percentage* Even under the best of conditions the mining Industry is dangerous, therefore safety for the men should be one of the prime considerations in choosing a particular method. It should obviously be economical since Its purpose is biasiness. The development of our civilization and industry rests directly upon fuel consumption of which coal is the main resource. On the other hand, mining is a wasting as­set, and the coal resources are running short. Thus, the method chosen should yield the highest recovery percentage. Last, but not least, there is another important factor that we are confronted with today, namely, speed. Industry is growing from day to day, and so is the need for fuel. Consequently, the method used should give the highest pos­sible output per day. This last factor might be considered economically in two respects: (a) the life of the mine is going to be shortened, making a quick return of capital .invested possible, (b) the production per man rate is in­creased and thus the mining cost is decreased. To be. able to establish a mine as described above, the following conditions in that particular area should be CHAPTBR OF COf'IPARISON rc,ining percentage_ industry Darticular its bRsiness. res ts consurnption \vhich . ',lasting as-set, is growing from day to day, and so is the need for fuel. Consequantly, the method used shOUld give the highest pos­sible output per day. This last factor might be ccnsidered economically in two respects: (a) the life of the mine is going to be shortened, making a quick return of ca-aital _invested -possible, (b) the .~ roduction D~ er man rate is in-creased and thus the mining cost is decreased. 69 thoroughly studied: (1) Natural or physical conditions of cover overlying the coal bed (main and immediate roof separately), (a) Thickness (b) Type of rock or rocks (c) Presence of hydrostatic pressure (d) Location of gulch and creek, if any, on the surface• (2) Natural or physical conditions of the coal bed itself, (a) Thickness (b) Dip of the seam (c) Structure, cleats and cleavage, friable or massive. (d) Strength of coal (3) Character of floor; whether or not it heaves (4) The value of surface as compared with the value of coal in place. The method of pillar extraction used might be cheap for mining, but may result in subsidence on the surface. Inasmuch as no two areas have exactly the same conditions, no definite rules can be set forth for choosing a mining method, A detailed study of each area or mine is therefore necessary and conclusions drawn from the data obtained. , , or roor s epara tely) • or or ir sur~ace. itselr. or structure, or surrace or ror surrace. tvTO cendi tions, method. or rrom CHAPTER XII COMPARISON General.- All of the mines that are described in the first part of the thesis are using the room-and-pillar system of mining. The mines are developed initially with either shaking conveyors, or a combination of shaking con­veyors and mobile loaders. Upgrades or raises are usually driven with shakers. The slope entries, as downgrades, are driven with track-mounted mobile loaders combined with rope haulage. In driving level entries and rooms either shakers or mobile loaders are used. With the shakers, rooms are driven at a 90 degree angle to the entry. With mobile loaders, the angles range from 35 up to 60 degrees to allow shuttle cars and mobile loaders to maneuver easily. These angles may also be affected by the structure! and the pitch of the coal. Generally, the depth of rooms, in either case, does not exceed 300-ft. This might be called the "effective distance" for the transporting equipment used. Mining with Hand Loading.- Direct hand loading in coal mines, especially in this country, became obsolete a long time ago. ^t still might be applicable in countries where labor is cheap enough not to warrant buying expensive mining equipment. Today hand shoveling is only used in cleaning up purposes. General.-- Ali and-pillar mounted structure ft. distancelf translJorting Loading.-- It anplicable 'warrant 70 Shaking Conveyors.- For many years, the shaking conveyer was the major piece of loading equipment in the coal mines. Row they are being replaced by mobile loaders. The tendency of replacing shakers in the Utah mines is greater than in Wyoming and Colorado (with regard to those visited). At present, the Sunnyside Mine of Utah Fuel Company is using mobile loaders, with the exception of two duckbill equipped shakers and one continuous miner. This mine average 18.6 tons of coal per man. The Castle Gate Mine of the same company uses 12 shakers and only a few mobile loaders, and averages 9.0 tons of coal per man. The Kenilworth Mine of the Independent Coal and Coke Company employs only one or two shakers and the rest are mobile loaders. They get an average output of 10-11 tons per man. The Geneva Coal Mine, the newest and most modern of all, employs a wide range of loading and transferring equipment, including various types of mobile loaders, shakers, and belt and chain conveyors. This wfcrm has an average output of 8 tons per man. This figure is not its true production rate, since the coal is not being mined to full capacity. The Union Pacific Coal Company's mines in Wyoming, such as Reliance, Stansbury, and D. 0. Clark, are mainly developed with shaking conveyors. Today few mobile loaders are being brought in. These mines range in the rate of output per man from 8 to 10 tons. Conveyors.-- conveygr Now 70. sh~~ers averages mobil,e mine nroduction capacity_ o. 72 The Imperial Coal Company's mines in Weld County, Colorado, such as the Imperial and Eagle, are good examples for comparing shaker and mobile loader operations. These two mines are under the same supervision and have almost the same natural conditions. The coal in both is lignite with nearly the same thickness and structure. The main difference is that the Imperial Mine uses shakers solely, working mainly on barrier extraction under tender roof con­dition. This mine gives an average output of 10 tons of coal per man. On the other hand, the Eagle Mine employs only shuttle cars and mobile1 loaders in rooms and develop­ment work. This mine gives an average output of 15 tons per man. As can be seen, the mobile loaders generally give a higher output per man than do shaking conveyors. Of course, not only the loading equipments, but many other factors must be weighed. These factors are the roof condition, the coal itself, the behaviour of the floor, the type of work (develop­ment, pulling pillar, or extracting barriers) and the supervision. Main objections to the shaking conveyors are as follows: (1) More skilled work and hand loading is needed (about $0-70 percent of mined coal is removed with duckbills or pans, but the rest is shoveled by hand). (2) Difficult and slow to move from one place to the next, and therefore, time consuming. (3) Desired speed in removing coal is not met. Contrasted with these disadvantages are the following Company1s employ~'::: mobile'load~rs outuut s~2king ~O-70 73 advantages: (1) Less operating power consumed than with the mobile loaders. (2) Greater efficiency is realized in driving entries and raises. (3) Its initial cost is low. (4) Hand picking (cleaning) is possible when rock parting in the coal seam is mined. (5) In places where the floor heaves, shaker can be used to better advantage than mobile loaders. Track-Mounted Mobile Loaders.- This type of equip­ment is almost always used in the driving of entries and slopes where tracks are needed. In loading, it cleans the face properly, but unfortunately, maneuvering loaded and empty cars is a big problem in its operation. That is, after one car is loaded, there is a delay until it is haul­ed to the parting and an empty one brought back. Shakers are superior in this respect, but are not good in downgrade slopes. Crawler-Mounted Mobile Loaders.- At present, Joy loaders and shuttle cars are in favor in the coal mine®. Their power consumption and initial costs are higher than the shakers, but their greater speed and productivity makes them as economical as shakers. However, the rooms that are driven with mobile loaders make an angle of 35 to 60 degrees vhen vlhere Loaders.-- t~Tpe equip-ment 1oading, Cars reSDect, Mounted Loaders.-- mineB. povJer 74 instead of 90 degrees, thus leaving a diamond-shaped pillar with sharp corners. Ihese sharp corners have a tendency towards crushing, thus creating a serious problem. Continuous Mining.- Among the mines visited, only the Sunnyside Mine of Utah Fuel Company employs one con­tinuous miner. This machine was introduced in the late fall of 1949 and has been experimented with ever since. Because this machine eliminates face preparation and has a high output, it has some very promising features to offer the coal mining industry. However, certain operational problems remain to be solved. These problems are: (1) Quick transportation of the coal from the continuous miner to the tipple. Two ears are used with the continuous miner, one surge bin car (right behind), the other a standard shuttle car for trans- . porting the coal. As the face advance and the distances increase, the shuttle cars cannot keep up with the continuous miner. (2) Since the advancement is very rapid, the rate of gas liberation is increased. The present ventilation system should be improved to provide the required amount of air. (3) The miner produces much dust and fine coal, (4) About 10-15 gallons of spray water per minute is necessary. The spray and the flying coal particles These Mining.-- or utah reatures '~roblems cars trans­porting r ate posing a real problem. 75 make the coal face invisible. As a result, the operator has a hard time staying within the cutting limits. (5) The cutting bits of the machine wear out too soon and require too much time to change. (6) In loading, the miner does not clean the face too well; thus, some hand shoveling is required. After these problems are solved, the continuous miner will start a new era in the coal mining industry with the following advantages: (1) Drilling, cutting and blasting are eliminated, as well as the respective machines and men needed for them. productivity;.. Pillar Extracting Methods.- The common methods of extracting pillars in the districts studied are: (1) open-end, (2) pocket-and-stump, and (3) splitting or a modification of it. The open-end and the pocket-and-stump methods are very similar in general principles; they differ in the system of supporting the roof along the rib line. In the former, the pocket is open on the goaf side and the roof is supported with timbers. In pocket-and-stump method a narrow pillar of coal (stump) is left along the goaf side to support the roof while driving the pocket. As a result the open-end method (2) A continuous mining operation can be insured, with high speed and productivity.~. (3) Its operation requires only 6 men, an operator, a helper or cleaner, a mechanic, a shuttle car driver, a surge bin operator, and one man on the belt. Methods.-- su?ported r esul t 76 gives a higher recovery rate than the pocket-and-stump. But the pocket-and-stump method is safer. The splitting method, as described previously with the respective mines, gives the lowest recovery rate of all. The Sunnyside Mine uses a modification of the splitting method that gives a little higher recovery rate than the ordinary system. In order to establish a safe and economic pillar re­covery, the following should be taken into consideration: (1) Proper extracting method should be used and carried on systematically. C2) The best size of pillar should be determined. (3) Right length of rib line should be maintained. (4) Suitable break line should be chosen. (5) Complete recovery of coal should be obtained if Face Preparation.- The preparation of the face is as important as any other phase in mining the coal. Improper face preparation nullifies the efforts of machines and crews to maintain high efficiency of operations. The face preparation may consist of the following stages: (1) cutting, (2) drilling, and (3) shooting. The coal is very seldom shot on the solid. Undercutting is the predominant method now used in preparing coal faces. The reason for undercutting is that it gives better breakage of the face, limits height of face and gives excellent conditions for Docket-:Mine re-covery, be' r2) possible. Preparation.-- trackless mining. Top cutting is employed to leave a layer of coal to help support the bad roof, or to eliminate an impure band near top of seam. Shear cutting may be practiced to release the coal burden and to make blasting easier. This is done either at the center or at both sides of the face. Side shearing also serves to limit the shape of the entry driven. Drilling order changes with the thickness of seam, bed condition and the type or character of coal. Undercut coal faces are shot with top holes and center "breaker." The rib holes give an arching effect and support the top coal. These rib holes are usually drilled parallel to the ribs. Breaker holes are sometimes angled toward the center. The top holes are drilled parallel to the roof if blasted with explosives; when cardox is used, the top holes are dropped a little and angled upwards, e.g. Imperial and Eagle mines. The depth of the holes are 6 inches shorter than the cuts, to avoid shoot­ing on the solid, and ranges from 6 to 8.5-ft. for shakers and mobile loaders, respectively. In shooting the coal, permissible sheathed explosives are used in all the mines studied. Only Imperial and Eagle mines use cardox for blasting the coal when large lumps are needed, according to the market demand. To meet the U.S. Bureau of Mines regulations, every hole after being charged is stemmed. Transportation.The system of transportation in the breaker. II ft. Transportation.-- The 77 78 districts studied are: (1) a combination of rope- and track-haulage, (2) track-haulage and shaft hoisting, and (3) track-haulage, rope-haulage and belt conveyors. Direct-current, trolley locomotives are used in the main entries with track-haulage. In strike or cross entries either cable reel or the storage battery locomotives are em­ployed for gathering purposes. As far as safety is concerned, only the permissible type of storage battery locomotives will not cause a fire or explosion. But the main objection to this type is that it is not powerful enough to use on the main lines. For gathering purposes its power is sufficient, but it requires charging station, and its frequency of charging is a nuisance. Since the main haulage road serves also as the main air intake, it lessens the danger of a fire hazard from that respect. With the introduction of large capacity mine cars and suitable safety devices, track-haulage on the main entries is quite satisfactory when a coordinated, smooth running system is established all over the mine. The belt conveyor system is gaining favor in use. Today some mines are using belt conveyors advantageously even in cross entries and rooms, as well as on the main slopes. The main objection to the belt conveyors is the high initial cost and its heating effect that may lead to a fire or explosion. With a high degree of precaution and careful dust handling, the danger of fire may be overcome. The high initial cost may be partly cancelled by eliminating the number of cars track­haulage, track­haulage, surficient, ofa systEm allover With a high degree of precaution and careful dust handling, the danger of fire may be overcome. The high initial cost may be partly cancelled by eliminating the number of cars needed (when a trackless mine is established) and by its higher efficiency. Furthermore, it is claimed that tracks in the temporary entries can seldom be relaid more than twice. The life of a belt is much greater. A final out­standing feature in favor of the belt conveyor Is that it seems to be the unique transportation system that may com­plete the cycle of the continuous mining operation. is 79