Wet Grinding Versus Dry Grinding for Deep Cleaning Ultrafine Coal by Flotation. Technical Progress Report

摘要

Laboratory froth flotation tests were conducted with dry- and wet-ground minus-400-mesh coal to determine the effect of grinding methods on clean coal recovery and product grade. A laboratory air-classifying impact mill was used for the dry grinding, and a stirred ball mill (attritor) was used for the wet grinding. Products of as near the same size distribution as possible were prepared by each method, i.e., nominal minus 27 micrometers ( mu m) with a mean particle size of 10 to 12 mu m. The test results show that the dry-ground coal is more floatable (i.e., greater weight-percent recoveries were obtained at any given reagent dosage), but the wet-ground coal provides substantially lower ash products at equivalent yield. For example, the dry-ground coal yielded about 20 wt % to over 80 wt % froth product with frother reagent dosages of 0.1 to 0.5 pound per ton of dry solids (lb/ton), respectively, and the product ash contents ranged from 2.0 to 4.0%. The wet-ground coal, on the other hand, yielded about 25 wt % to a little over 70 wt % froth product with frother reagent dosages of 0.2 to 0.5 lb/ton, respectively, and the product ash contents ranged from about 1.5 to 2.0%. 4 figures, 2 tables. (ERA citation 10:001819)