Proximate and Microscopy Analysis of Coal in Tamalea Village, Bonehau District, Mamuju Regency, West Sulawesi Province, Indonesia

Abstract

Coal deposits that have been found in Tamalea Village, Bonehau District are one of the coal resources found in West Sulawesi Province, Indonesia. Coal study in this area will provide information about the characteristics of coal in the West Sulawesi area. This study aims to determine the initial composition of coal quality based on proximate analysis and the appearance of minerals in coal using microscopic analysis. The results of the proximate analysis of coal show that the moisture content ranges from 3.65% to 8.42%, the ash content ranges from 5.59% to 64.96%, the volatile matter shows a value vary from 17.69% to 62.83%, and fixed carbon ranged from 13.70% to 46.76%. The results of microscopic analysis showed the presence of several dominant minerals, namely clay, quartz, and pyrite. The presence of these dominant minerals affects the quality of coal, namely the high content of ash, and allows variations in the total sulfur content. The appearance of the mineral pyrite under a microscope shows that pyrite is formed through syngenetic and epigenetic processes. The most dominant processes in the coal samples studied is the epigenetic process. Syngenetic pyrites are mostly small framboids composed of tiny micro-crystals. Epigenetic framboids vary in shape and size with large and massive microcrystals. The pyrite content as a sulfur carrier shows a specific vertical distribution trend with the same pattern, namely the ash content and pyrite mineral appearance are higher in the coal seam adjacent to the floor compared to the coal seam adjacent to the roof.