JOHANNESBURG (miningweekly.com) – The declining quality of raw coal makes the control of coal product increasingly difficult and the beneficiation of raw coal more important, Council for Scientific and Industrial Research (CSIR) coal processing engineer Johan de Korte told delegates at the Fossil Fuel Foundation’s conference on clean coal technologies on Tuesday.
The declining quality, he explained, was as a result of a number of mines re-mining the pillars left by previous bord-and-pillar mining operations.
There is also a growing trend to reprocess discarded coal from previous operations to recover low-grade thermal coal.
With beneficiation, De Korte believes the industry can increase coal quality and provide a consistent coal quality to the market.
In turn, he noted that would allow for lower-grade coal reserves to be used appropriately.
“The decreasing quality of run-of-mine coal in South Africa provides limited application potential, especially without beneficiation,” he warned.
Beneficiation, or processing of raw coal, involves the crushing of the coal, screening of the coal into specific size ranges and subjecting the coal to dense medium separation to upgrade the coal to a specific ash content or heat value, as well as the correct size range required by a specific industrial process.
He explained that coal is mainly used in combustion, gasification, carbonisation and liquefaction processes, with each process requiring coal of a specific quality. “Raw coal, as mined, cannot be used directly,” De Korte pointed out.
Beneficiation is of particular importance in South Africa, he said, adding that South Africa’s coal was known to be difficult to process.
“Most of [South Africa’s] coal needs to be beneficiated to be used,” he told Mining Weekly Online.