Optimization of the crushed middlings rewashing process of Tangkou Coal Preparation Plant

In producing the grade-8 clean coal by Tangkou Coal Preparation Plant, it is found that the middlings product still contains some coal that is up to the standard of the grade-10 clean coal in quality indices. To address this issue, work is made on screening and float-and-sink analysis of the middlings before and after crushing to explore the conditions required for the recovery pf the grade-10 coal from the middlings before its crushing and after it is crushed down to a size of 6 mm or 3 mm. Test result show that the higher the degree of liberation of the intergrown coal, the more conducive it is to the recovery of the coal; and when viewed from the perspective of yield of clean coal and amount of fine coal generated through crushing of middlings, a relatively higher recovery of the coal can be obtained when the middlings are crushed down to size of 6 mm. On the basis of the test results, the middlings rewashing process of the plant is optimized through addition of sizing screen and crusher, allowing the plant to see a rise of the yield of clean coal by 0.56 percentage point.