Investigation of Fine Grinding and Flotation to Produce Superclean Coal

摘要

Laboratory flotation tests were conducted with dry-ground and wet-ground coal to determine the effect of grinding methods on clean coal recovery and product grade. A laboratory jar mill, a stirred ball mill, and an air-classifying vertical impact mill were used for grinding the coal samples. Products of as near the same size distribution as possible were prepared by each method (i.e., nominal minus 27 mu m with a mean particle size of 10 to 12 mu m). The test results show that dry-ground coal is more floatable at lower reagent addition levels, but wet-ground coal provides lower ash products. For example, a dry-ground coal yielded about 40 wt % to over 70 wt % of froth product with frother reagent dosages of 0.2 to 0.5 pound per ton of dry solids (lb/ton), and the respective product ash contents ranged from about 2.0% to 3.0%. A wet-ground coal, on the other hand, yielded under 30 wt % to a little over 70 wt % froth product with the same frother reagent dosages, but the ash contents ranged from about 1.0% to 1.6%. 5 refs., 5 figs., 2 tabs. (ERA citation 10:036035)