Adsorption mechanism of a new combined collector (PS-1) on unburned carbon in gasification slag

Abstract

Coal gasification fine slag (CGFS) is a type of solid waste produced during coal gasification, in which unburned carbon (UC) severely restricts its resource utilization. The removal of UC from CGFS is considered an urgent problem. This study applies PS-1 (a mixture of kerosene and oleic acid at the ratio of 7:3) to improve the flotation separation effect of carbon from CGFS. The flotation adsorption mechanism of PS-1 on UC is revealed by experiment/molecular dynamics simulation and characterization analysis. Results show that long-chain hydrocarbons in PS-1 are adsorbed on the non-polar region of UC by Van der Waals force, while -COOH groups in PS-1 are adsorbed on the polar sites of -COOH and -OH of UC by hydrogen bonds. The synergistic effect of long-chain hydrocarbons and -COOH groups in PS-1 improves the hydrophobicity of the UC surface. Compared with traditional collector kerosene, the combustible recovery rate of foam products can be increased to 68.0%. Collector dosage can be reduced by approximately 50% using PS-1. This study can provide essential guidance for the design of CGS flotation collectors and help realize the comprehensive utilization of coal gasification solid waste.

Keywords: Adsorption mechanism; Flotation; Gasification slag; Molecular dynamics simulation; Waste utilization.