HYDRO21797 - Laserfiche WebLink

Home Browse Search

COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division Rationale - Page 2. PERMIT NUMBER: COG-850000 INDUSTRY DESCRIPTION: Coal is mined is the state using both surface mining and underground mining methods. In surface mining the coal is located relatively close to the surface. The overburden and topsoil are removed using equipment such as truck-mounted shovels, bulldozers, and wheeled tractor scrapers and later replaced or reclaimed. Surface mining is typically accomplished using a dragliae. IIndergrouad mining methods are used for coals located farther under the surface where the removal of the overburden is not economically feasible. underground mining involves blasting down to the coal, drilling and cutting to eatract the coal, sad removing coal using equipment such as conveyors or shuttle cars. The raw coal or "run-of-mine" coal may require processing prior to use. This processing Ss referred to as coal preparation. Coal preparation is the process of upgrading raw coal by physical means and includes crushing, sizing, cleaning, and refuse disposal operations. The initial step in the coal preparation process often involves crushing of the coal with crushers or pulverizers to remove large rock fractions and to free impurities such as clay, rock, and pyrite from the coal. The coal is then sized using equipment such as screens, cyclones, and separators. Different crushing and sizing techniques are used for fine coal and coarse coal processing. Coal cleaning is a preparation process performed to improve product standardization, to increase the heating value of the coal, and to reduce the ash and sulfur content of the coal. Coal cleaning processes include both wet and dry cleaning methods. However, many coal pteparation plants use water in the separation process. The mining of coal does not involve the use of water other than small amounts for dust control and equipment cooling. The major sources of water entering the mine area are precipitation, groundwater infiltration, and surface runoff. Water is considered to be a hinderance to mining activities and the removal of water from the active mine area is generally required to ensure the efficiency sad safety of the mining operation. For underground mines removal involves pumping the water out of the mine area. The majority of the coal preparation processes use water. The amount. of water used at coal preparation facilities varies widely depending on the degree of cleaning, the equipment or processes used, and the characteristics of the raw coal. Examples of unit operation requiring water include wet screening, tables, jigs, cyclones, gravity sad heavy media separation. Additionally, water is used for equipment cooling, dust control, sad as a transport medium for the coal between process units. The major types of wastewater in the coal mining industry are: 1. Mine Drainage - Any drainage and any water pumped 'or siphoned from as active mining area or post mining area.