Study of schemes for comprehensive utilization of low-rank coal slime resource

China is endowed with a huge low-rank coal reserve. High-efficiency and comprehensive utilization of the slime of such coal is of vital significance for ensuring healthy growth of the coal industry and boosting the utilization rate of coal resources. In order to explore the approach for attaining the objective, the fine low-rank coal slime produced by Xiaobaodang Coal Preparation Plant is taken as the object of study. The study is made in line with the local market needs and based on results of screening and float-and-sink analysis and flotation test. Through tests on drying and roasting of the bricks made with flotation tailing plus other materials physico-chemical analysis of the mixtures, as well as application of the process for pulverizing flotation concentrate, the scheme for realizing comprehensive utilization of Xiaobaodang coal slime is finally defined as follows: upgrading the low-rank coal slime through flotation; sintering the bricks made with flotation tailing using tailing′s self-heat; the residual heat in making bricks is recovered and transformed into vapor and high-temperature flue gas to supply heat externally as a heat source; and the flotation concentrate is pulverized as a clean coal resource after being further dried by the residual heat in making bricks. As indicated by study results, through secondary flotation of Xiaobaodang Plant′s fine coal slime, the tailing and concentrate products have an ash of ≥75% and ≤ 8%, respectively, which can meet the needs for making bricks and producing pulverized coal product; the materials used are up to the criterion for making bricks, and the residual heat can be recovered for reuse; through optimization of the process for producing pulverized coal, a product with a size of < 0.075 mm and a moisture of ≤ 8% can be obtained; and the investment required for implementing the scheme totals 153.8079 million yuan with a payback period of 2.89 years, and the net profit that can be gained per year a amounts to 53.2610 million yuan. It can be seen from the investment estimate and economic benefits, the scheme is technologically and economically feasible for its ability to realize comprehensive utilization of all materials and residual heat.