Filtration of coal tailings aided by a novel physical conditioner carbon–containing fly ash

Abstract

ABSTRACT Chemical conditioner is employed widely to improve the filtration rate of coal tailings in coal preparation plant. However, little attention has been paid to physical conditioner which could be economic and effective. In this study, the carbon-containing fly ash (CCFA) was used to improve the filtration rate of coal tailings. The filtration experiments of coal tailings were conducted with the addition of CCFA. It was found that the filtration rate increased with the increase of CCFA addition amount from 0 to 150 kg/t. The permeability of the filter cake, which was obtained in the framework of the Darcy’s filtration theory, was found significantly increased after CCFA conditioning. The nuclear magnetic resonance (NMR) measurements of the filter cake indicated that the addition of CCFA increased the porosity of filter cake. The properties of CCFA were analyzed by scanning electron microscopy (SEM), NMR, and inverse gas chromatography (IGC). The results indicated that the unburned carbon particles in CCFA contained rough surfaces and the porosity of CCFA was as high as 58.30%. The hydrophilicity index revealed that CCFA was much more hydrophobic than the particles in coal tailings. These results supported that CCFA provided more water transmitting passages in the filter cake due to its high porosity and hydrophobicity, so the filtration rate of coal tailings was improved.