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Coal rail car topping system commissioned in Moz

26th September 2014

By: Mia Breytenbach

Creamer Media Deputy Editor: Features

  

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Water treatment and process services company Nalco Africa, an Ecolab company, has completed the first installation of its rail car topping system at a coal mine in Mozambique’s Tete province.

“The rail car topping system, which was completed and commissioned in August, comprises a spraying system at the mine’s rail loadout station. The system automatically sprays the coal in the rail cars with a chemical reagent – Nalco DustBind technology – before it is transported to the port,” says Nalco Africa mining industry technical consultant Jan Botha.

DustBind technology is a biodegradable encapsulating aid formulated to bind fine particles on rail cars, stockpiles and other materials, creating a bound crust on a mineral surface to reduce dust created by handling or windy conditions. It is easily diluted and applied, and reduces wind and water erosion on stockpiles.

DustBind technology also resists re-emulsification once it is dry. It also has a flexible bond that resists break-up once applied and has low equipment maintenance costs.

Botha notes a growing awareness within the mining industry about the financial and environmental impact of coal dusting, and stresses that DustBind technology not only reduces the environmental impact incurred when fine coal is lost to prolonged wind exposure, but also curbs product waste and, therefore, revenue losses, as fine coal is blended with coarse coal and exported as coking or metallurgical coal, which has a high export value.

“It has become necessary for the mining industry to limit these losses,” he says, stressing that wind and distance travelled may account for 0.5% of coal loss, which means that if a mining company transports 100 000 t of coal, about 500 t can be lost during transportation alone.

Botha adds that DustBind technology has to be able to withstand prolonged movement and wind exposure over extensive distances, as coal trains in Southern Africa travel to the Beira and Maputo ports, in Mozambique, or to the Richards Bay Coal Terminal, in South Africa. The product was, therefore, tested in wind tunnels over distances of up to 600 km and over varying time frames to ensure the least amount of coal dusting and fine coal product losses.

DustBind technology revealed a greater than 90% reduction in fine coal losses, according to research data.

OreBind Processing Technology
In addition to its coal rail car topping systems, Nalco Africa will for the next 18 months focus on providing its OreBind processing technology, which is used for the rapid dewatering of mine tailings, to the South African coal and other mining industries.

Botha explains that OreBind process technology is a combination of reagents and equipment that works with application experience to quickly release water from tailings, while producing a high-solid cake-like material for easier handling and disposal.

“By providing a quicker recovery of contained process water, the material, such as coal, can be stacked more easily, thereby taking up less space. It also reduces potential loss of water from the tailings dam through evaporation,” says Botha.

Moreover, by removing more of the contained water from the underflow, less water is lost from the circuit, while a lower volume of expensive water needs to be brought on site to produce process water.

Botha adds that the OreBind process also assists in reducing the use of, or the need to replace dewatering capital equipment, such as filter presses or centrifuges, which are more expensive to operate than this new process.

While this technology and treatment process has been implemented in Australia since 2007, Botha points out that Nalco Africa has only been supplying minerals processing products and technologies to the South African industry for the past four years.

Further, mining industries in the Middle East and Africa (MEA) have only recently become aware of these processes and their potential, says Botha, noting that, as the OreBind technology is still a new endeavour for the MEA region, Nalco will also conduct a feasibility study on the potential of this process for South African collieries.

Nalco Africa plans to implement two OreBind processing systems at two smaller coal projects in the Mpumalanga Central basin by the end of the year, which will each act as pilot plants to gather and provide feedback on the projects’ tailings performance.

“We are mainly focusing on smaller coal mines to obtain a footprint in South Africa and to establish an idea of the value that OreBind technology can provide to the local coal mining industry,” says Botha.

Nalflote Focus
Nalco also remains focused on its fine coal recovery programme for the South African mining industry – Nalflote high-performance flotation reagents – which improve the performance of coal flotation circuits, says Botha, adding that demand for Nalco supplies for the coal flotation programme has increased by about 30% in the past 18 months.

Products for the programme include frothing agents, promoters and collectors, as well as hydrophobising agents, coagulants and flocculants, which increase filter performance or capacity.

Edited by Samantha Herbst
Creamer Media Deputy Editor

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