Effect of ultrasound on the true flotation of lignite and its entrainment behavior

In this study, the ultrasound was fixed in the pulp zone of flotation cell and its effect on the true flotation of lignite was analyzed. Flotation results indicated that the simultaneous ultrasound treatment increased the concentrate yield and decreased the concentrate ash content. Screening analysis of flotation products revealed that the ultrasound could crush coarse coal to fine coal and scanning electron microscopy (SEM) tests indicated that the ultrasound could reduce the coverage of high-ash coal fines on the coarse particle surface. Thus, the flotation recovery of coarse lignite particle was increased. In addition, the true flotation and entrainment of −0.074 mm fine particles were studied by the sink-float test and the method of Trahar. It was found the ultrasound significantly enhanced the true flotation of fine particles and improved the overall water recovery in lignite flotation

Comparative study of separation performance of a spiral and dense-medium cyclone on cleaning coal

Spiral separators and dense-medium cyclones (DMCs) are widely used for separation of −1 + 0.125 mm fine coal. In this study, testing was carried out using −1 + 0.125 mm fine coal with low near density material to produce a concentrate, using both a spiral and DMC. Clean coal with 8.31% ash content was obtained with the spiral at 37.39% yield, 47.76% combustible recovery and 0.150 Ep value. For the DMC, the combustible recovery of clean coal at the ash of 8.31% ash was improved to 80.84% at 62.98% yield, and 0.118 Ep value. The advantage of the DMC is further proved by analysis using Fuerstenau upgrading curves