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Title	Experimental Observations and a Postulated Mechanism of Relase of Iron During the Combustion of Illinois #6 Coal
Creator	Baxter, Larry L.; Mitchell, Reginald E.
Publisher	Digitized by J. Willard Marriott Library, University of Utah
Date	1988
Spatial Coverage	presented at Pittsburgh, Pennsylvania
Abstract	A series of investigations of iron release during the combustion of illinois #6 coal are reported. Experimental measurements are described in which 40-70 percent of the iron in the coal is released within a 25 ms period immediately following coal devolatilization. This iron release dominates the evolution of all other elements in this coal (excluding sulfur) on a mass basis. The release is consistently observed under realistic combustion environments over a particle size range from 75-125 J.Lm and a gas oxygen concentration range of 6-12 percent. Statistical uncertainty of the results is also reported, but is small compared to the measured effect. Further experiments and analysis were conducted to determine the mechanism of iron release. Forms of iron with sufficient volatility to explain the results as a vaporization process were investigated. None was found which could reasonably be expected to form under the experimental conditions. Further experimentation suggests that the mechanism is related to the chemical reactivity of the iron species with oxygen and that the release proceeds through the chemical formation of an iron fume.
Type	Text
Format	application/pdf
Language	eng
Rights	This material may be protected by copyright. Permission required for use in any form. For further information please contact the American Flame Research Committee.
Conversion Specifications	Original scanned with Canon EOS-1Ds Mark II, 16.7 megapixel digital camera and saved as 400 ppi uncompressed TIFF, 16 bit depth.
Scanning Technician	Cliodhna Davis
ARK	ark:/87278/s6nc63rk
Setname	uu_afrc
ID	4888
Reference URL	https://collections.lib.utah.edu/ark:/87278/s6nc63rk

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Title	Page 23
Format	application/pdf
OCR Text	Show Once all the pyrite has been converted to pyrrhotite, oxygen can diffuse to the particle surface where it reacts with the residual sulfide. Magnetite is formed on the surface of the particle as pyrrhotite is oxidized. 1.14 FeO.877S(s) + 1.2367 02 4 0.33 Fe304(s) + 1.14 SO(g) 683 -201.24 kJ/mol 02 (R3) Concurrently, the particle temperature rises due to the exothermic oxidation reaction. Vhen the particle temperature attains the melting point of pyrrhotite, the solid pyrrhotite portion of the particle begins to form a liquid phase. Simultaneously, the pyrrhotite is oxidized the magnetite shell is dissolved in the melt, and it is assumed that the product of oxidation is an iron-sulfuroxygen melt. FeO.877S(s) 4 FeO.877S(I) 684 = 341.15 kJ/kg 1.14 FeO.877S(I) + 1.2367 02 ~ 0.33 Fe304(1) + 1.14 SO(g) 685 = -190.1 kJ/mol 02 (R4) (R5) The particle temperature remains constant during this step and the rate of melting is determined by dividing the rate of heat generation due to oxidation and transfer from the surroundings by the enthalpy change upon pyrrhotite melting. This step is completed when all the pyrrhotite has melted. Oxidation of the remainder of the sulfur in the Fe-S-O droplet takes place in the next stage. The model assumes that surface reaction kinetics do not contribute a significant resistance once a melt is formed,4 and that the overall oxidation rate is diffusionally controlled. However, allowance is made for the resistance to oxygen transport in the liquid melt. In the calculations, the liquid-side mass transfer coefficient is considered as an 4
Setname	uu_afrc
ID	4872
Reference URL	https://collections.lib.utah.edu/ark:/87278/s6nc63rk/4872