Beneficiation of coal pond ash by physical separation techniques

In this study, investigations to develop a beneficiation process for separating coal pond ash into various products were undertaken. To this end, coal pond ash samples with different particle size ranges were tested in terms of their washability characteristics in a float-and-sink analysis. It was found that coal pond ash was heterogeneous in nature consisting of particles that varied in terms of their size and composition. However, it can be made more homogenous using a gravity separation method. Therefore, the possibility of separating coal pond ash was tested on standard equipment typically used for gravity concentration. To increase the separation efficiency, coal ash was separated according to the size of the particles and each size fraction was tested using equipment appropriate for the corresponding sizes. A hindered-settling column and a shaking table were tested for their ability to treat the 1.19 × 0.074 mm size fraction, and a Falcon concentrator was evaluated for its ability to treat the −0.074 mm size fraction. The results showed that various marketable products, such as lightweight aggregate, sand and high-carbon fuel, can be recovered from coal pond ash using simple physical separation techniques.

Graphical abstractShaking Table in operation showing the steams of coal ash particles.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Coal pond ash was examined in terms of the size/gravity distribution and composition. ► Generally, the higher the density, the less carbon the ash particles contained. ► Physical separation of high-carbon ash for low-carbon ash was demonstrated. ► A multi-stage separation scheme was developed for beneficial use of coal pond ash.