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Dry Coal DMS technology supplier FavorSea Africa is offering a South African coal mine the opportunity to be the first in the country to benefit from the dry dense medium separation (DMS) beneficiation technology developed by China’s technology partner.
The dry DMS beneficiation technology will be supplied through a toll treatment deal, whereby FavorSea Africa will take on all capital risk involved in designing, constructing and commissioning a 220 t/h processing plant.
Our technology partner has already built and commissioned a 440 t/h dry DMS process facility consisting of two 220 t/h plants at the State-owned Huainan Mining Group coal mine, in China. The facility has successfully separated coal feed sizes between -200 mm and +13 mm with an EP value of 0.055.
FavorSea Africa entered into a joint venture in 2016 to promote the dry DMS beneficiation technology in Africa, Australia, and the world market. and is now introducing the technology to the South African market.
The new technology addresses the country’s water scarcity issue, as well as power supply challenges, and is particularly suited to the operating conditions in the Waterberg coalfield, in Limpopo, where coal mining activity is on the rise, says FavorSea Africa director Barney Bai.
Dry DMS beneficiation of coal using dry magnetite and air in a fluidized bed technology has been researched from as early as 1926 in Germany, with many studies taking place and test pilot operations commissioned to find a commercial solution. In 1984, Professor Chen Qingru from China University of Mining and Technology developed the dens- phase, high-concentration, micro-bubble quasi-dispersion fluidized bed, dry coal separation theory which fuelled the start of the first commercial dry DMS coal beneficiation plants in China.
“The dry DMS beneficiation technology with air-dense medium fluidized bed uses air-solid (magnetite) suspension as a beneficiating medium whose density is consistent for beneficiation, similar in principle to the wet dense medium beneficiation using liquid-solid (magnetite) suspension as a separating medium. The portion of the feedstock with a density higher than that of the fluidized bed will sink, whereas the lighter portion will float, thus stratifying the feed materials according to their density,” explains the company.
In South Africa, coal is predominantly processed through a wet “float and sink” beneficiation process that uses a water-based slurry of magnetite. This extremely water-intensive process not only places the country’s limited water resources under pressure but also has the potential to pollute to the environment, particularly groundwater. Thus, the strict regulations put in place by the departments of Mineral Resources and Water Affairs to control water use by the mining industry.
As dry DMS beneficiation technology requires no water for the processing of coal, no water use license is required and water treatment costs are eliminated, as it is potential harm to the environment, Bai highlights, only limited water supplies are needed for dust suppression.
The technology also matches or betters the yields achieved through conventional wet coal beneficiation, with run-of-mine crushing costs reduced, owing to the large top size (200 mm) the technology can beneficiate. Subsequently, only the Middlings portion of the feed needs to be crushed and reprocessed, enabling even higher yields to be achieved.
Further, compared with conventional -80 mm (max) wet DMS beneficiation plants, the dry DMS beneficiation technology produces fewer coal fines, consumes 40% less power (about 400 kWh) and requires half the footprint.
However, the technology is not without its constraints. Currently, the dry DMS beneficiation technology can only accommodate less than 5% surface moisture in the feed material and -13 mm feed material needs to be screened out before the beneficiation process. To address these challenges, an online drying process will be introduced in the future and technology is being tested to accommodate +6 mm.
Bai says even with the introduction of the online drying process, which would only be employed during the rainy season, the technology will still use less electricity than wet DMS beneficiation plants.
Already in discussions with one local coal mine, Bai tells Mining Weekly that the right mine for its toll treatment agreement will preferably produce export grade (RB1 and RB2) coal product; however, Eskom-grade coal will also be considered.
He notes that the plant, requiring property of 150 m x 150 m for its assembly, would be ready to ship to South Africa in one to two months.
FavorSea Africa has operated in South Africa since 2005 when it was founded by its parent company FavorSea Industrial Channel, a strategic export partner of top Chinese mining and construction sector players. The company has been working with the Coaltech Research Association, in Johannesburg, since 2008. Coaltech will be responsible for doing efficiency testing on coal samples from large mining companies operating locally, such as Glencore and South32, looking to trial the dry DMS beneficiation technology once the South African plant is operational.
EDITED BY: Creamer Media Reporter