Preliminary Study on The Reduction of Mercury Content in Steam Coal by Using a Pneumatic Vibrating Concentrating Table

Abstract

Mercury content in hard coal is relatively small. However, considering the large amounts of coal burned in Poland, considerable quantities of mercury are released to the atmosphere. Mercury occurs mainly in pyrite and marcasite included in mineral matter in coal, but it is also present in coal organic matter. Certain, sometimes substantial, amounts of mercury are found in the roof and bottom layers of coal fields, which pass to run-of-mine coal in the mining process. It is possible to remove impurities with gangue coming from these layers and impurities originating from stone inserts in coal fields. It is also possible to remove the liberated iron sulphide particles. But, as practice shows, wet enrichment methods (jigging, flotation) are often imprecise. The concentrates contain certain amounts of gangue and sulphur compounds which results in the passing mercury compounds to commercial products. The Katowice Branch if the Institute of Mechanized Construction and Rock Mining has been conducting research on method for deshaling of dry run-of-mine for several years. In the study a system equipped with a pneumatic vibrating concentrating table was used. The system, when properly adjusted, allows effective removal of these contaminants. It is therefore possible to deshale the excavated material and also to remove mercury compounds occurring in the high density fractions. This article discusses the sources and emissions of mercury, its content in hard coal and legal considerations regarding mercury emissions. Also presented are the preliminary results of research on mercury removal using a pneumatic vibrating concentrating table.