Investigation of Various Methods of Recovering Solids from Solids-Bearing Effluents Produced by the Preparation and Charging of Preheated Coal to the 6.5-M Oven at BCRA

摘要

A study was conducted to examine, evaluate and compare different methods of dewatering effluents containing carryover fines. Of the limited number of dewatering systems tested, the most efficient were as follows: For treating the preheater-washer effluent, the rotary vacuum drum-filter with belt discharge performed very well, giving the cleanest filtrate and highest recovery. The decanter centrifuge produced a dirtier centrate which, however, up to some limit, should have no adverse consequences. For treating the charging-main effluent, excellent performance was shown by the pusher centrifuge, provided that the tar content of the solids was not excessive. The peeler centrifuge also performed well but with a lower throughput relative to machine size. The decanter centrifuge and the rotary vacuum drum-filter both performed well but gave a wetter product than those from the pusher and peeler centrifuges. The rotary vacuum drum-filter had a much higher rate of throughput with charging-main effluent than with preheater-washer effluent. For treating mixtures of preheater-washer and charging-main slurries, the rotary vacuum drum-filter with belt discharge and the decanter centrifuge performed well but the decanter centrifuge gave a dirtier centrate (filtrate). No large-scale trials of the peeler centrifuge were carried out on mixed slurries, but laboratory trials indicated that this machine should operate well and give the driest product, although little is known about the peeling and heel-blinding characteristics of the dense mixtures of dry fines. For efficient and economical operation, pre-thickening of solids-bearing effluents is required in all of the systems tested. The choice of system for any specific application will of course be influenced by considerations of the relative costs. (ERA citation 05:021569)