The current situation of coal dry cleaning equipment in China

Coal is China's important strategic resource, yet along with incessant exploration and utilization of coal resources, the premium-grade coal resources are gradually decreasing. So, upgrading of coal through separation has become inexorably a necessary approach. The wet cleaning method is high in water consumption and cost, and is difficult to be applied especially in arid and water-deficient areas while the dry method can make up the deficiencies of wet method. In order to allow the persons working in coal sectors to gain a deeper insight into the dry cleaning technologies, and push for further development of highly efficient and clean utilization of coal, the paper presents a detailed introduction to the main dry cleaning equipment currently available from multiple aspects, such as the air separator, compound dry separator, heavy medium fluidized-bed dry separator and intelligent dry separator, as well as their respective working principle, related research work so far made, and performance in practical application. The special features of each separator are briefly summarized as follows: the air and compound separators are suitable for treating extremely-easy and easy-to-clean coal with yet a relatively low efficiency; the heavy medium fluidized-bed version, through high in separation accuracy, can only treat a feed with a smaller top size, and its multi-hole air-distribution plate is liable to get blocked in operation; the intelligent version can treat a feed with a large upper and lower size and can be used instead of handpicking operation, but in the case of treating a feed with a smaller lower size, its separation sharpness would be affected; and in the case of treating a feed with a smaller size, the abovementioned separators all require the feed to be low in moisture, otherwise, the equipment would get plugged up by agglomerates formed by bonding of fine coal with dirts due to increase of viscosity of feed. Following the introduction to the state-of-the-art of the coal dry cleaning equipment, it is pointed out that in the future, the dry separators should be developed to have a higher adaptability to the variation of feed moisture and be able to operate in a combined mode for making it possible to realize whole-size dry separation.