Effect of Operating Parameters and Reagent Addition on Fine Coal Dewatering in a Screen Bowl Centrifuge

摘要

A six-inch continuous screen bowl centrifuge was employed in a pilot plant study designed to evaluate the effect of reagent addition, coal particle size distribution, slurry feed rate, and slurry feed solids concentration on the dewatering of finely ground Pittsburgh bed coal. The test results showed that 30%-solids slurry of minus-35-mesh coal could be dewatered to as low as 16% surface moisture with the addition of surfactant to the feed slurry. Without surfactant addition, the dewatered coal moisture level was about 20%. Similar tests with minus-200-mesh coal resulted in final product moisture levels of 21 to 23% with surfactant addition, and 25 to 27% without surfactant. With synthetic organic flocculant addition, on the other hand, the dewatered coal moisture content was always higher than without reagent. The increased moisture content appeared to be directly related to the molecular weight of the flocculant. Preparatory to the tests with reagents, several series of tests were run to evaluate the capacity of the centrifuge. These tests showed that feed rates greater than about 3 gal/min of 30%-solids slurry resulted in excessive coal losses in the effluent discharge. Ana feed slurry solids concentrations greater than about 30% at the 3 gal/min feed rate resulted in high product moisture content and excessive coal losses to the screen discharge. 10 references, 7 figures, 7 table. (ERA citation 10:001820)