DEVELOPMENT OF A PROCESS FLOW SHEET FOR A NOVEL BENEFICIATION PROCESS TO PRODUCE LOW ASH CLEAN COAL FROM HIGH ASH INDIAN COALS

摘要

Leaching or solid extraction is done to dissolve mineral matter in coal using a solvent. The acidic and/or basic components present in mineral matter react with the solvents, gets dissolved and then removed. The present invention describes a pilot scale process flow sheet for treating coals crushed to -30/-72 BS mesh size or fine clean coal obtained from flotation circuit coal for removal of ash-forming minerals which includes series of alkali and acid treatment steps under various operating conditions. The steps include treatment of the feed coal in an aqueous alkaline solution at an elevated temperature under atmospheric and elevated pressures followed by reaction/extraction with an aqueous acidic solution at atmospheric temperature and pressures. This is a process to produce low ash (~4.0-5.0% ash) clean coal from high ash Indian coals with 75-85% yield. The proposed pilot plant is envisaged to operate on a batch process. Each batch shall process 500kg of raw coal. The present invention is a step towards making chemical leaching process commercially feasible for various applications.