Dry cleaning of low-rank coals by low temperature carbonization and magnetic separation

Studies conducted on low temperature carbonization (LTC) followed by dry magnetic separation in the laboratories of Minerals and Coal Processing Section of Istanbul Technical University are reviewed. The -3 mm low-rank coal samples are subjected to LTC process at about 600°C for 15 min and then upgraded by magnetic separation. Under optimum conditions, a substantial decrease in ash and, more importantly, on total and particularly organic sulfur is achieved. A systematic study on the mechanism of remarkable improvement in sulfur removal together with the literature findings suggests the formation of an iron-sulfur coordination compound in coal. The practical application and feasibility of this process utilizing the byproducts is illustrated on a flowsheet.