Challenges and opertunities of coal cleaning in India

India is bestowed with huge amount of coal reserves. But most of these reserves are inferior in quality with high ash ranging from 20-45% and not suitable for direct use for industrial applications. These coals need prior beneficiation to reduce the ash content below the required level for efficient utilization. The common practice of coal cleaning in India is by size reduction, screening and treating by heavy media bath, heavy media cyclone and flotation. The coal is crushed to below 13 mm and classified at -13+6.0mm, -6.0+0.5mm and -0.5 mm. Coarse coal is treated by HM baths and the middle fraction is treated by HM cyclones. The fines below 0.5 mm are sometimes mixed with clean coal or processed by flotation based on the ash content. But most of the Indian washeries are not giving desired performance due to operational problems, design defects and frequent change in feed coal. Lot of clean coal is lost in rejects and tailings. The perforce needs to be improved and clean coal yield are required to be enhanced by modifying the existing washeries. Lot of coal fines generated at washery contain around 25-40% ash based on the source of raw coal. The production of fines are increasing day by day due to mechanized mining and crushing to fines sizes for washing. Around 15-20% coal mined is reported as fines which need more attention for selecting proper beneficiation circuit for utilization. The widely practiced technique for fine coal cleaning is flotation and Indian coals are not responding well for this technique due to oxidized nature and poor liberation characteristics. Advanced techniques are required to recover more clean coal from fines from the point of view of conservation and environmental pollution. This presentation deals with challenges and opportunities available for coal cleaning in India and possible solutions. Recent developments in fine coal processing techniques like spirals, advanced gravity techniques, flotation, column floatation and oil agglomeration were reviewed and their possible applications for treating Indian coal is suggested to produce 12-14% ash clean coal from both coking and non coking coals. The R&D efforts made by CSIR-IMMT in this direction are also presented.