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 coal processing engineer Johan de Korte has said.
He was speaing at the Fossil Fuel Foundation’s conference on clean coal technologies, which was held last week.
The declining quality, he explained, was the result of a number of mines remining 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 said, the industry could increase coal quality and provide a consistent coal quality for 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 the 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 was 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 was 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 [before it can] be used,” he told Mining Weekly.