Deep recovery study for coking coal washery rejects using a comprehensive process

Washery reject is a by-product discharged during coal preparation, in which there are still certain amount of valuable combustibles. The recovery of clean coal from washery rejects is of great significance for protecting China’s scarce coking coal resources. The main purpose of this work was to design a deep process that can maximize the recovery of clean coal from a coking coal washery rejects with about 50% ash and test the technical feasibility of the process. Based on fundamental analyses, the high ash fractions of +0.2 mm and +1.80 kg/cm3 were firstly removed from the raw coal sample via hydrocyclone and spiral separator. Then, the remained parts having an ash of 27.57% were ground, pre-conditioned, and separated by flotation. The results showed that, under the optimum process parameters, a maximum yield of 24.47% clean coal with 12.23% ash can be recovered from this washery rejects. The ash content of the washery rejects increased from 50.10% to 62.37% after this treatment. This study indicated that it was technically feasible to achieve deep recovery of clean coal from washery rejects, which was of significance for the treatment of coking coal tailings.