Ash Reduction of the Tailings of Agh-Darband Coal Washing Plant by Flotation Method

One of the major coal mines in the eastern part of Iran is Agh-Darband mine which is located in Sarakhs. Agh-Darband plant works with a content of less than 37% ash at inputs and about 12% ash in the product. Due to the equipment being depreciated and the lack of optimal conditions for the processing system, a large amount of the coal in feed is entered to the tailing part so that ash content in the tailing is about 75%. The purpose of this research is to investigate whether the flotation method can process the mine tailing with 75% ash content and reduce it to return to the processing circuit. For this purpose, various flotation tests were performed on 70 kg of tailing of Agh-Darband mine. The optimum conditions was obtained at neutral pH with 2000 g/t of oil collector, 30 g/t of pine oil as a frother, and a solid content of 18%, which the ash content of coal and recovery were 34% and 45%, respectively. In addition, using the experimental design software (DX7), the mechanical parameters of the cell such as mixer circulating speed, the distance of the mixer from the bottom, the aeration rate, skimmer circulating speed, and cell volume were optimized. Optimal values of parameters were mixer circulating speed= 1227.2 rpm, the distance of the mixer from the bottom= 0.13H, the aeration rate= 1 (completely open), skimmer circulating speed= 8.49 seconds, and the cell volume= 1 L, which resulted in the percentage of ash= 35.34% and the recovery= 52%.