The effect of ultra-fine coal on the flotation behavior of silica in subbituminous coal reverse flotation

Abstract

In this study, X-ray Photoelectron Spectroscopy (XPS) was used to analyze the elements on the surface of subbituminous coal, and reverse flotation was introduced to float subbituminous coal. The effect of ultra-fine coal on the flotation behavior of silica in coal reverse flotation was discussed by comparing the flotation performance with two different artificial mixed flotation feedings, with ultra-fine coal (UFC, −45 μm) or without ultra-fine coal. The comparison results showed that the existence of UFC reduced the flotation rate and the recovery of silica, as well as the separation efficiency of subbituminous coal reverse flotation. Compared to the flotation performance of feeding with UFC, the concentrate ash content of feeding without UFC was lower (9.18%), and the separation efficiency was higher (68.69%). Total Organic Carbon Analyzer was used to test the adsorption quantity of collector by coal and silica to explain the mechanism. Conclusions were obtained that ultra-fine coal particles could adsorb more collector due to their larger specific surface area, leading to less collector left in the pulp to float silica particles. Selective flocculation reverse flotation method could increase the separation efficiency of coal reverse flotation with appropriate dosage flocculant.