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 ۳۷% ash at inputs and about ۱۲% 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 ۷۵%. The purpose of this research is to investigate whether the flotation method can process the mine tailing with ۷۵% ash content and reduce it to return to the processing circuit. For this purpose, various flotation tests were performed on ۷۰ kg of tailing of Agh-Darband mine. The optimum conditions was obtained at neutral pH with ۲۰۰۰ g/t of oil collector, ۳۰ g/t of pine oil as a frother, and a solid content of ۱۸%, which the ash content of coal and recovery were ۳۴% and ۴۵%, respectively. In addition, using the experimental design software (DX۷), 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= ۱۲۲۷.۲ rpm, the distance of the mixer from the bottom= ۰.۱۳H, the aeration rate= ۱ (completely open), skimmer circulating speed= ۸.۴۹ seconds, and the cell volume= ۱ L, which resulted in the percentage of ash= ۳۵.۳۴% and the recovery= ۵۲%.