Time studies in underground coal mining

Machine performance is the key to higher production and bigger profits in present day coal mining. By far the most important machine in a mechanized coal mining operation is the mobile loader. It must load the coal that pays for the entire operation, and its performance, therefore, is the deciding factor controlling success or failure of the mine. This paper attemps to analyze the loading and hauling cycle of a producing section, including the actions of the mobile loader and one or more shuttle cars. A simple and effective method of conducting time studies is outlined in the first chapter by which not only the loading operation but also other operations, necessary to keep the mobile loader in coal, can be analyzed and studied. In the second chapter an attempt is made to evaluate time studies conducted according to the outlined method. The studies had been made in Kenilworth Mine and Castle Gate Mine. Both mines are located near Helper in Carbon County, Utah. They are properties of the Independent Coal and Coke Company. Their productions are 3, 000 and 2, 000 tons per day, respectively. The room and pillar method is used exclusively in both mines. All openings are driven eighteen to twenty two feet wide and ten to twelve feet high. Pillars are recovered on the retreat* The loading is done with Joy 11 BU loaders in all sections. The loaders discharge into Joy 10 SC shuttle cars that empty directly into mine cars. Recommendations are made in the third chapter which could improve the performance of mobile loaders in general and the operations of Kenilworth mine and Castle Gate mine in particular. The theoretical considerations in the last chapter deal with requirements that must be met by a high producing section. They also show some limitations of the use of mobile loader units in conventional room and pillar mining - at least with the present day equipment.