Concentration of main elements in mineral matter of Polish coking coal and its cleaning products

Abstract

The chemical composition of coal mineral matter, and particularly the content of major elements (Al, Si, Fe, Ca, K, Na, Mg), plays an important role in the processing and use of bituminous coals. Mineral matter is the ballast, reducing the calorific value of the fuel. The aim of the study was to analyze the concentrations of main elements of coking coal mineral matter and products of its cleaning in heavy media, jiggers and flotation machines. Analysis of elements was performed through the technique of the atomic absorption spectrometry AAS. The results of main elements concentrations of coal mineral matter and its cleaning products are discussed in relation to each operation of mechanical treatment. As a result of the cleaning process in heavy media, the content of mineral substances decreased seven times, mainly due to the removal of components such as silicon, aluminum and iron from coal. Similar results were obtained in the case of cleaning in jiggers, leading to a significant reduction of the contents of silicates and aluminosilicates. In both cases, there was an increase in the content of sodium. Despite the significant reduction of the contents of alkali metals’ compounds, their content in concentrates as converted to oxides is quite high (0,43–0,81% of dry coal). The lowest alkalis content is the displayed by a coal concentrate from the flotation process dewatered in a centrifuge.