2013-04-05_PERMIT FILE - C1981019 (10)

Home Browse Search

RULE 2 P1J' 121VII`l, suspect material. If the problem area is greater than one acre in size, it will be necessary to cover the area with at least five feet of acceptable material before the application of topsoil. After removal of the overburden, the coal seams are exposed. As the coal seams are exposed, they are cleaned using auxiliary equipment then either drilled and shot with explosives or ripped to prepare the coal for loading and removal. When explosives are needed, the drilling is performed by an auger drill. The drilling pattern is in the range of 12 feet by 12 feet, but is dependent upon the actual coal seam thickness. Drill holes are loaded with either ANFO or a waterproof explosive, if the holes are wet, to a typical powder factor of about 0.2 pounds per ton. When the coal is ripped rather than shot, large bulldozers with ripper attachments will fragment the coal sufficiently for smooth loading operations. Once the coal has been prepared for loading by either blasting or ripping, a rubber -tired front -end loader loads the coal into haulage trucks. Following loading, these haulage trucks transport the coal along in pit roads to the primary crusher located just outside of the mining area as shown on the Existing Structures - South Map (Map 22). In order to visualize the overall mine plan, a range diagram was drawn. This diagram is found as Mining Range Diagram (Map 24) and depicts operations by draglines in combination with shovels and trucks. The past and anticipated annual production tonnage of coal is shown in Table 2.05 -2, Historic and Anticipated Annual Coal Production. Coal to be mined at he Colowyo operation is present in at least 8 separate seams ranging in thickness from 2 feet to 15 feet. The seams to be mined are designated from upper most to lowest as Y (Y3 and Y2), X, A (Al, A2 and A3), B (Bi and B2), C, D (D1 and 132), E, and F. To date, very little of the Y2, Y3 and A3 seams have been recoverable. Coal from the mining area is transported to a coal crushing facility as shown on the Existing Structures - South Map (Map 22). Details of the coal crushing and load -out facilities are included in Section 2.05.3 under the heading of Mine Facilities. After coal recovery by conventional truck/shovel and dragline methods has reached the maximum economical recovery limit, Colowyo has the potential of using a highwall miner when the conditions allow. The highwall miner can recovery additional reserves left in the pit face that were deemed non- recoverable by conventional surface mining methods. This new highwall miner technology can recovery coal up to 1600 feet in advance of the final pit wall with an approximate coal recovery ratio of 40% to 60 %. Once the coal has been recovered and stockpiled in the pit, then the coal will be transported to the primary crusher and train loadout by coal haul trucks. Refer to Map 23 for the location of potential highwall mining areas. As soon as possible after the coal is removed from the mining area and sufficient room is available for back - filling, reclamation begins. In general, rough backfilling is completed by the over- burden trucks and bulldozers since the operation has reached a "steady state, " as shown on the Mining Range Diagram (Map 24). As stated earlier, overburden material removed ahead of the operation is transported by truck around the active coal mining areas and deposited into the mined -out areas. Either dragline may periodically be utilized on the backfill material to assist in final spoil placement and in achievement of the planned final topography. Following the completion of mining, temporary overburden stockpiles will be removed and placed back into the open pit. Specifically, the top 75 feet of the temporary overburden Rule 2 Permits 2.05 -4 Revision Date: 8/3/10 Revision No.: MR -101