Study of the semi-direct flotation process and analysis of its operating performance

The flotation feed is found to be low in density as a result of the use of combined washing process,namely,scalping-out of fines from raw coal,jigging of coarse coal and flotation of fine coal.To revert this situation,the semi-direct flotation process is proposed based on the result of analysis of the direct and concentrated flotation processes.It is intended to determine the feasibility of realizing coarse coal jigging with mud-laden water and the optimal concentration of flotation feed.As indicated by test result,the use of the semi-direct flotation process makes it possible to effectively increase and make on-line adjustment of density of flotation feed according to variation of content of fine coal in raw coal,decrease the rate of feed to both flotation and thickening systems and downsize the equipment for use in these systems because of the increase of flotation feed concentration even in the instance of treating all the fine coal present in the whole washing process.The use of the flotation process at Dongyu Coal washery had led to a reduction of the total initial capital cost by 10.80 percentage points and a drop of total operating cost by 8.60 percentage points.