Due to some features of coal slime, such as high moisture, high viscosity, high water-holding ability, and low heat value, it is very difficult to apply it to the industry.
Before the process of coal slime, it has some features. Firstly, the particle size of it is very small and it has too many particles. Especially, the amount of the particle which is less than 200 mesh accounts for about 70%-90%. Secondly, it has high ash content and quite low heat value. According to the ash content and heat value, coal slime can be divided into three categories, including the one with 20%-32% ash content and 12.5-20MJ/kg heat value, the one with 30%-55% ash content and 8.4-12.5MJ/kg heat value, and the one whose ash content is more than 55% and whose heat value is 3.5%-6.3%. Finally, coal slime has high viscosity. Because, in general, there is too much clay mineral of coal slime and it has lot of moisture and small particle, most of coal slime is sticky, some of which has a certain mobility. All these features lead to the difficulties in the stack and storage and transport of coal slime, which may not only waste valuable coal resource but also cause severe pollution. Sometimes, it may restrict the normal operation of the coal washing plant, which will be a tough problem for the coal washing plant.
Since China’s reform and opening-up(December, 1978), with the rapid development of national economy, Chinese coal output has ranked first in the world and there have been great changes in the market. In China, coal process has rapidly developed and the output of coal slime has obviously increased so that the comprehensive utilization of coal slime has already been an issue which needs to be dealt with urgently.
With the constant development of industry and science in China, surplus coal slime can be utilized again. The slime drying machine adopts the new techniques, which can crush and scatter the coal slime and then dry it with heat, which makes the coal slime process be of succession, industrialization, and automation. The moisture content of coal slime can be decreased to 12% from 25%-28% by the coal slime drying process. Due to the introduction of some working procedures of the coal slime drying process, including the preliminary crushing procedure, scattering, and anti-inner wall scaling procedure, the drying efficiency of the slime drying machine has been greatly increased.
The processed coal slime which has been dried can be used as the material to make coal briquette, which can be used for industrial boiler or residents life. It can also be used as the material for power plant or foundry industry to increase fuel efficiency, lower the production cost, and to increase economic benefit. As the additive for brick factory, it can increase the hardness and compression strength of the brick. As the additive for cement plant, it can improve the property of cement. Besides, the coal slime with some certain components can be used as the industrial material.