Improving Densification of Fine Coal Refuse Slurries to Eliminate Slurry Ponds

摘要

A coal preparation plant separates the material it receives into a product stream and a reject stream, which may be further divided into coarse and fine refuse streams. The fine refuse slurry, which is a blend of water, coal fines, silt, sand, and clay particles, is commonly disposed of in an impoundment. The coal industry is required to monitor the impoundment constantly and maintain the dikes holding the slurry. There have been several incidents of impoundment breakthrough, resulting in to heavy loses of life and property. In this paper an advanced thickening technique known as "Paste Thickening Technology" marketed by Dorr-Oliver EIMCO, was evaluated for dewatering of the fine coal tailings. The technique utilizes DEEP CONE Thickener TM, which is specially designed to concentrate tailings into high percent solids so it could discharge as a paste. The thickened material could be stacked at a low angle of repose rather than stored in a pond. Thus, the fine refuse slurry ponds could be completely eliminated. Results obtained at a coal preparation plant showed that the waste slurry could be thickened to about 55% solids and could be pumped to the disposal site. The DEEP CONE Thickener was also found to be effective in dewatering of fine clean coal slurry.