1599 coal was feed to washery for beneficiation to produce about 5.9 Mt of metallurgical washed coal and imported 57.6 Mt to meet the demand of coking coal to produce metallurgical coke. Over the last 5 years, about 20-25% of coking coal produced was washed before utilisation with average yield of 40%. The reason for diversion of coking coal to the non-metallurgical sector is gradual deterioration in the quality of raw coal over the years due to depletion of good quality coking coal reserves leading to poor performance of old washeries. The conventional washing technologies of old washeries are unable to supply coals of ash 1718% as desired by steel industries. Advance beneficiation has been identified as a requirement to cater the deteriorating raw coal quality (LVMC coal) and meet the increasing demand of metallurgical coal in India. This will reduce import of coking coal and saves exodus of FOREX Reserves. New research has emphasised the implementation of new technologies of beneficiation in order to have improved clean-coal recovery from high ash coal. Most of the Indian coking coal washeries are already operating at 13 mm as top size of coal for coarse coal washing, at the same top size the yield of clean coal with 18% ash is poor. Decreasing the top size to below 13 mm enhances the liberation and hence the recovery of clean coal and ease of washing also enhanced due to distribution of NGM to higher gravity section. Intermediate Size Beneficiation (ISB) and Advanced flotation cell technologies have identified reducing ash % without sacrificing yield. ISB utilizes intermediate circuit (3rd circuit) versus the standard two-circuit layout (coarse and fines circuit) for processing fine coal of size range (1/0.5mm – 0.25/0.15 mm) and is able to enhance 2-4% clean coal yield with same ash level. ISB typically utilizes technologies such as small diameter/ Fine DMC (Dense Medium Cyclones), Reflux Classifiers, Teetered Bed Separators, etc. Advanced flotation technologies for ultra-fine coal washing (<0.25 mm) such as Column flotation cell, Jameson cell, etc. are highly effective in attaining lower clean coal ash with same/ higher yield and minimizing misplacement of coal values in tailings over conventional mechanical flotation cell. The LIMN software used in coal processing for flowsheet design and modelling of coal washing circuit through the use of washability data is recommended for optimization and better recovery of cleans from high ash coal. Usage of computer models for optimizing the process through artificial intelligence, machine learning, and predictive analytics has also been investigated to increase the separation efficiency of beneficiation processes. The separation efficiency of a gravity-based beneficiation equipment is expressed as Ep (probable error) value, is as shown in equation (1). Y1=~:;@~2; # (1) Where, 4} is the density at which 75% of the material is recovered, and 4# is the density at which 25% of the material is recovered. Policies like Atmanirbhar Bharat (self-reliant India), Coking Coal Mission are initiated by the government to decrease reliance on foreign coal by investing in coal washeries through policy intervention. The expected influx of private-sector participation and foreign investments in coal mining and processing is likely to boost the domestic supply chain. Furthermore, Coal India Limited has proposed to set up new washeries, employing next-generation coal cleaning technologies, to increase the domestic supply of clean coal. The drive towards self-sufficiency in coking coal, coal and a multi-pronged approach would need to be adopted; such as investment in advanced washeries by introduction of modern coal-washing technology and use of AI-based predictive analysis for increasing separation efficiency. Utilization of off-grade coal, by the development of technology for the use of high-ash coal in coke making. Alternative technology R&D by adopting CTL and CTG technology to diversify utilitarian approaches. There is a high chance that, through such endeavours, India will completely overcome its dependence on imported coking coal. Figure 2 shows the percentage of research focused on coking coal optimization over the years. There is decline in traditional washing technologies and a rise in AI/ML for process optimisation in coal beneficiation for improvement in clean coal output. Furthermore, there is a significant rise in policy-driven strategies, indicating a move towards self-sufficiency and sustainable management of coal resources. This paper aims to present designing of coal washing flowsheet using LIMN simulator by reducing the top size of raw coal feed to 10 mm and use of advanced beneficiation technologies like intermediate size separator - Reflux Classifier/ Fine DMC, fine coal separation in Column flotation cell for maximum recovery of clean coal. Decreasing the top size of raw coal feed to 10 mm will improve the liberation and washability characteristics as finer crushing helps in distribution of NGM to higher gravity section. By leveraging these innovative beneficiation methods, this study seeks to contribute to reducing coking coal import, enhancing energy security and supporting sustainable practices within Indian coal sector.
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