Separation characteristics of CrossFlow separator for beneficiation of high ash Indian fine coal

The paper outlines the efforts to reduce the ash content of fine-size (−0.50 mm) high-ash Indian coal in a counter-current teeter bed separator, i.e. a CrossFlow separator. The tests conducted in the CrossFlow separator by varying the water injection flow rate and bed pressure reveal that an ash reduction of about 4.71% (from 34.94% to 30.23%) could be possible for −0.50 mm size coal. However, when the separation was analyzed by splitting it as coarser coal (−0.50 + 0.075 mm) and fines (−0.075 mm) independently, an appreciable reduction in ash content of about 11.0% was noticed in coarse fractions. In comparison, only a marginal ash reduction was possible for the finer fraction (−0.075 mm). Further, the size and density-based partition curves were plotted to understand and depict the separation behavior of the coarse fraction (−0.50 + 0.075 mm). The present investigation concluded that both size and density effects prevail in separating −0.50 + 0.075 mm coarse coal, while the separation fines below 0.075 mm are influenced by hydraulic entrainment. The effectiveness of separation of coarser and finer fractions has been evaluated by “Separation Efficiency.” Further, unified characteristic partition curves have been plotted to establish the prevalence of size and density effects in the CrossFlow separator and mathematically modeled.