What is slime?

Coal slime generally refers to the semi-solid substance formed by pulverized coal containing water, which is the product of coal production. According to different varieties and formation mechanisms, their properties are very different, and their effectiveness is also very different, which can be roughly divided into the following categories. 1. 1 flotation tailings of coking coal preparation plant are generally a kind of waste abroad, and their properties are similar to those of washing gangue or middle coal. Because of the different coal quality, the quality of flotation clean coal slime varies greatly. For example, the extraction rate of gas coal in Huainan is only 30% ~ 40%, and the ash content of this slime is relatively low, and the coal quality is close to clean coal. The coal in Pingdingshan is fat coal or 1/3 coke, and the extraction rate of flotation clean coal can reach 70% ~ 80%, so the ash content of flotation tailings is high, and the coal quality is close to that of gangue washing. According to the different recovery processes of coal slime, the physical properties of coal slime are quite different. For example, the coal slime recovered by the filter press has a relatively uniform particle distribution and weak viscosity and water-holding capacity, which is conducive to reducing moisture. For example, the filter-pressed coal slime in Pingdingshan No.8 Coal Preparation Plant, after being piled up for nearly half a year in dry season, appears dust when grabbed by grab bucket, and the total moisture is close to10%; The other is slime sedimentation tank or tailings pond, which realizes solid-liquid separation and produces slime according to the principle of natural precipitation of solid particles in water. The process has the function of particle size classification, coarse particles are easy to precipitate, mostly concentrated near the entrance of slime water, fine particles are in the middle position, and very fine particles are at the end. Terminal mucus has high viscosity and high water holding capacity, similar to glutinous rice balls. It is thin and soft. After several months of drying, the surface looks dry and the internal water content hardly drops. This mucus is the most difficult to handle. 1.2 slime produced by coal water slurry, such as slime produced by power coal preparation plant and slime produced after coal hydraulic transportation, is better than raw coal in some cases, and is often mixed with finished coal in small quantities. If the amount is too large and only a small amount is mixed, a large amount of high-quality slime may be produced, which will have a negative impact on the economic benefits of coal mines in addition to proper treatment. 1.3 Coal slime entrained by mine drainage and coal slime washed down by waste hills are dirty coal slime, which is characterized by small quantity and unstable quality, but generally better than flotation tailings. 1.4, before 1980s, coal slime was the main fuel for people. In order to facilitate storage and use, briquettes and honeycomb briquettes are generally made of coal slime mixed with a small amount of loess.