No matter in the primary process of raw coal, or in the process of coal preparation, crushing work is a key step, which directly influence the coal sales and subsequent process investment, directly affects the economic benefits of coal enterprises. With further development of market economy and the improvement of machine technology, putting forwards some new requirements for traditional crushing, mainly show as below:
1.1 Market demand
Coal user is very strict to the requirement of product size, different users have different particle size requirements, and the requirements changing with the market change, once can not meet the requirements, the coal is dull sale or the customer refuse to pay for the over ranging of granularity, which directly influence the enterprise benefit. Meanwhile, the price is differ in different sales period and different particle size, enterprise that aim to achieve maximum benefit, must rely on crushing work.
1.2 Coal deep processing and the need of clean coal
In the process of coal washing, in order to achieve monomer separation between gangue and coal, increase the specific surface area of raw material, improve the coal quality (lower ash content, increase calorific value), remove the harmful material such as sulfur and phosphorus contained in the coal, reduce the atmospheric pollution during coal combustion, we must take effective crushing operations.
1.3 The requirement of washing equipment
Different washing equipment has different washing range. It must going through crushing process to meet the requirement of the washing machines. If the granularity of the material going to be crushed beyond its size limitation, it is very likely to cause blockage, and reduce the efficiency of the washing equipment. In order to solve the problem, it is necessary to make sure the granularity of the material by crushing procedure.
1.4 Reduce the possibility of over crushing
The over crushing phenomenon is quite wasteful during the crushing process. It also influences the economic benefit of enterprises. Over crushing can increase the moisture content and system pressure of the coal. The efficiency of selecting fine coal has been reduced as a consequence. With the increasing requirement of environment protection the cost of powder coal processing soars accordingly. As a result, it is essential to reduce the powder coal to the least level.
1.5 The Demand of Energy Saving
Currently in most dressing plant, the cost of crushing process takes up over 40% of the total expense. Moreover, the crushing equipment investment account for 60% of all dressing plant investment. Although, the proportion the crushing production cost and the foundation construction investment is quite low compared with the overall investment of the dressing plant, the production and construction fees of coal material preparation system has great influence on economic indicator. Hence, increasing the crushing capacity and reduce the energy consumption of crushing process has significant meaning.