Tong Gong Coal Mine Opperations
Coal extracted from Tong Gong coal mine is for both industrial and home use. Steam coal is trucked to a nearby railroad cargo station which is approximately 500 meters from the mine. The 500 meter road from the coal mine to the railroad cargo station is being improved to reduce trucking time.
The “longwall” coal mining method employed at Tong Gong coal mine, typical for the Chinese coal mining industry, uses longwall panels and retreating face methods to produce approximately 80% to 90% of the mine’s output. Incline development and longwall gate entries account for the remaining output. The general mine layout is a series of longwall panels extending from the left and right of three parallel inclines. The inclines currently extend for approximately 300 meters following the coal seam, and may be further extended up to 1,000 meters covering the entire length of the seam. The main incline houses compressed air lines, telephone and signal lines, high voltage cable, and rail for hoisting operations. A service incline houses surface water supplies for fire fighting and underground water discharge lines. A secondary parallel intake incline adjacent to the main incline assists in ventilation. Longwall panels extend from the inclines to the reserve boundaries defined by property limits or geological features. The entire main block reserve area is currently recovered from the present inclines and planned extensions.
The longwall technique in use at the mine is semi-mechanized sublevel caving. It consists of a single hydraulic support with a 40 kilowatt motor powered by a small capacity advanced fuel cell. Drilling and blasting methods are used to break up the coal face and sublevel caving recovers the remaining coal. As the face line retreats along the strike of a seam, the roof strata collapses and allows the coal face to operate under manageable stresses. Sublevel caving techniques are widely used in the PRC.
All raw coal is hand loaded and transported down the face line by a chain convey or by coal cars. Rock material is used for floor ballast with the excess sent to the surface for disposal. The mine is equipped with a 2-meter diameter hoist that is capable of hoisting eight coal cars, each with a 1-ton capacity. Two air compressors are provided for underground air tool use. Diesel locomotives, 3- and 5-ton capacity, are used for underground haulage. We receive our electrical power from state-controlled power lines as well as local power lines. Power is supplied to underground workings through a high voltage cable.
Normal water inflow into the mine is controlled by three multistage centrifugal pumping units and dual discharge lines. During high water periods, all three pumps can be utilized. The mine’s ventilation system includes an exhaust fan on the surface of the main incline. Auxiliary fans are used as needed. The present mine fan is capable of satisfying projected ventilation demands.
Mining Xing An Coal Mines
Current mining operations at Xing An coal mines take advantage of the region’s weather conditions. For approximately 100 days from October to April, the frigid weather causes permafrost at these mines, enabling coal to be extracted by dynamite mining. Additionally, the permafrost eliminates the need for any shaft support. Thus, mining operations are ongoing during the entire 100-day period, with three shifts of eight hours each per day. To extract coal, controlled explosive charges are placed into holes that are drilled into a coal seam. After the explosives separate coal from the seam, a backhoe loader scoops the coal up from the ground and into a waiting haul truck with 8-ton capacity. Once the truck is loaded, it is driven to the surface where the coal is emptied on to a sorting machine. The sorting machine sorts the coal into three sizes, and separates out rock through centrifugal action.