Coal mining equipment

Coal crusher and Coal separator
After coal is mined, it is transported to the storage. Before it is used, we usually crush it into particle using coal crusher. There are several types of coal crusher.

Jaw crusher for coal is used in primary crushing process. It is also the very common coa crusher. Impact crusher and cone crusher is usually used as secondary and Tertiary coal crusher. Now, some coal mine use portable coal crusher for crushing, it is convenient, high efficient.

Coal Mill and Coal Classifier
In heat power station, gashouse and coal methane making, coal is usually grinded into powder. Coal mills are applied to the drying and grinding of coal. Through the wind force, the finished products are directly put into dynamic coal mill separator. The equipment is mainly compromised of feeding device, main bearing, rotary part, discharge device, driving device and lubrication system. All large size air-swept coal mills are equipped with drying room which can make the moisture content of dried coal reach 8-10%.

The ball mills use unique integrative partition plate and discharge grate plate to balance the levels of materials in each chamber, increasing the grinding efficiency. Besides, a new type lining is used to adjust the rotary speed while the optimized gear design is applied to prolong the lifetime of gear. The bearing shells are processed by hydrostatic lubrication of high-pressure dilute petrol station, so it becomes more stable in operation.

Vertical mill has the features as follows:

1. Simple process. One mill can grind, dry and classify materials at the same time.
2. Small area occupied, compact layout, low weight and low investment in basic construction.
3. High grinding efficiency and low power consumption of unit product.

Use of Coal
Coal has four major markets: electric utilities, industrial/retail users, the steel industry and exports. Electric utilities use more than 86 percent of the coal produced in the United States. Upon close examination, it is clear that price has been a major deciding factor in coal's increased use. More than 57 percent of the electricity generated in the United States comes from coal. In an electric power plant, coal, like oil and natural gas, is burned to produce heat. The heat is used to change water into steam. The steam then turns the blades of a turbine, spinning the generator, producing electricity. Before the coal is burned it is crushed and pulverized to the consistency of face powder.

Coal's second largest market is industrial and retail users. Among the industries using coal, the largest consumers are chemical manufacturers, users of stone, clay and glass, paper mills, primary metal industries and the food industry. Industry uses coal as a chemical feedstock to make dyes, insecticides, fertilizers, explosives, synthetic fibers, food preservatives, ammonia, synthetic rubber, fingernail polish, medicines, etc.

The third largest market is the iron and steel industry, where coal is used to made into coke. Coke is derived from bituminous coal through heating in airtight ovens. The lack of air prevents the coal from burning and converts some of the solids to gases leaving coke.

The fourth market segment is exports. The top five foreign markets are Canada, Japan, Italy, Netherlands and Brazil. U.S. coal distributed to foreign countries in 1988 totaled 95 million short tons (76 million to overseas destinations and 19 million to Canada). Major reasons for the decline in United State's coal exports from the all-time high of 112.5 million tons in 1981 are stiff competition in the international marketplace and worldwide economic conditions.

To a lesser extent, kaolin clay is used as a refractories, in fiberglass and in portland cement. Once the clay is heated to over 500 C it becomes calcinated, forming calcined kaolin. This product has a distinctive crystal structure providing enhanced brightness and opacity.