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Characteristics of Char from Low-Rank Coal Gasification

Asof Marwan, Arita Susila, Andalia Winny

Journal of Ecological Engineering

2023

Vol. 24, nr 4

78--84

The coal gasification process in this study aimed to increase the quality of low-rank coal (LRC) from lignite type to coal with semi-anthracite and anthracite grades with higher fixed carbon values. The gasification process was carried out at temperatures between 700-900 °C. In the initial stages of the study, the relationship between the increase in gasification temperature with the mass of coal and the gasification process time was investigated. The proximate and ultimate analysis was carried out to determine the characteristics of the raw materials used and the coal char produced from combustion. The analysis results are used to calculate the fuel ratio, where the fuel ratio is a parameter to determine the grade of coal. In addition, an SEM-spot EDS analysis was carried out on the gasified coal solids to ensure the fixed carbon content produced from the above process. The results showed that the gasification process could raise the grade of LRC into char products with semi-anthracite to anthracite, where the fuel ratio reached 10.84. From the product analysis results, the LRC coal gasification results using SEM-EDS showed that carbon reached 98.58%. The remaining inorganic elements in the product are less than 1.5%, such as Al, Si and K.

Beneficiation potential of a low-grade coal from the Emalahleni (Witbank) coalfield

Nyoni Sancho, Bwalya Murray, Chimwani Ngonidzashe

Physicochemical Problems of Mineral Processing

2020

Vol. 56, iss. 5

849--859

The challenge of coal depletion has, among other resolutions, forced countries such as South Africa which depend heavily on coal-generated electricity to consider low-grade coal to meet their energy requirements. The Emalahleni Coalfield has an abundance of low-grade coal in-situ and in discards obtained from the No. 4 seam. This research thus seeks to give a technical assessment of the beneficiation potential of such coal for use in power stations linked to the coalfield. To that end, gravimetric and flotation beneficiation techniques were used, and their demineralisation capacities were assessed using physicochemical and petrographic analysis techniques. The results obtained showed that demineralisation of the coal was possible; with 29.1 and 33.6% ash obtained for an ~50% mass yield from gravimetric and flotation beneficiation techniques, respectively, against a thermal ash content requirement of 25–34% for coal-generated electricity.