Mineral processing is the art of treating crude ores and mineral products in order to separate the valuable minerals from the waste rock, or gangue. It is the first process that most ores undergo after mining in order to provide a more concentrated material for the procedures of extractive metallurgy.
The primary operations are comminution and concentration, but there are other important operations in a modern mineral processing plant, including sampling and analysis and dewatering.
One thing that you have to keep in mind about the processing plant on a mine is that an entire operation’s production is only as rapid as the processing plant. If the plant falls behind, the excavation also needs to slow down and the mine loses money.
This is also the part of the mine with the most expensive equipment. Recently, a number of plants in the South African mining sector have become operational and with that, also displayed their state-of-the-art attributes.
“Roymec Technologies is a company that services the industrial and mining sector with the supply of tailor-made filtration and separation solutions and process equipment. We guarantee our client base in all 25 countries that we have supplied equipment to of our fullest commitment and highest service levels in all these regions,” says Roymec Technologies, Sales Director Hoosen Essack. “These agreements are an assurance that our commitment takes places on the ground.”
“We have also formally announced the realization of over two years’ worth of research that improves further our thickener and screening equipment performance,” comments Essack. “We’re pursuing several business development ventures in parallel that gives us depth, capacity and the science to continue providing world class process solutions to our clients across the globe,” he adds.
Enprotec was established based on the need for a mineral processing company capable of providing solutions for the recovery of ultrafine coal material. It has the capability to carry out environmental, economic and technical feasibility studies to determine the most viable solution to turn a waste stream into a viable product stream.
“The company has three key divisions – the projects and engineering division, the operational division and the process equipment division – with key technologies and expert skills forming the cornerstone of Enprotec’s business – now and into the future,” states Enprote’s Operational Director Jayson Jacobs.
Filtration in the works
The Hakhano colliery operates a coal processing plant and produces in excess of 1.5 million tons a year of domestic as well as export coal. Enprotec was contracted to design, supply, construct and commission a filtration plant at Hakhano. The purpose of the filtration plant is to eliminate the use of slimes ponds by dewatering the thickener underflow as arising ultrafine coal from the main plant.
“It is imperative that the moisture of the filter cakes is as low as possible for the water recovery to be as high as possible. Thus, the Enprotec plate and frame filter with full filter functionality was the ideal solution,” says Jacobs.
“With the ongoing increase in the demand for water, along with global water shortages and changing weather patterns, we decided that we needed to find a way to reduce water use at our mines, while also lessening our environmental impact, and one of our solutions was to embark on this project with Enprotec,” says Umthombo MD Vuslat Bayoglu.
Hakhano’s water use has dropped from 0.298 m3 for every ton of coal produced to 0.051 m3/t. “The amount of slurry produced was also reduced and a by-product of filter cake will now be produced, which can be sold off to certain markets,” he adds.
The Enprotec filtration plant eliminates the use of slimes ponds by dewatering the ultrafine coal from the main plant. For water recovery to be as high as possible the Enprotec filter comes standard with membrane squeeze and cake blow, which reduces water in the cake by between 5% and 8%, thereby increasing water recovery, Jacobs explains.
“This is the highest water recovery possible with dewatering equipment,” he adds. “Enprotec’s solutions alleviate Hakhano’s environmental problems associated with slimes ponds, and reduces the mine’s raw-water consumption by at least 60%. In July, while the plant was being commissioned, the water consumption was 43 000 m3 a month, compared with the 8 500m3 used in September, indicating a clear decrease in consumption and a step in the right direction,” Jacobs says.
A secondary objective of the project was to find a market for the dewatered product.The ultrafine coal of the Hakhano colliery meets the specifications for the thermal coal market but the difficulty is that sludge is neither easy to handle nor easy to transport to the power stations, says Jacobs.
“However, with the Enprotec technology, a dry filter cake is produced, which can easily be supplied to domestic power stations,” he adds. This is not a new technology but the improvement is that, for the first time, the life-cycle cost of the equipment is affordable. Historically, this was an expensive process; however, along with its Chinese partners, Enprotec has managed to make the technology affordable, he adds.
This is not Enprotec’s first filtration plant of this kind. “We designed, supplied, constructed, commissioned and also currently operate filter plants at the Kangra colliery, as well as at coal producer Anglo Coal’s Greenside colliery, but both these plants also have flotation plants, which makes the filtration application different from that of the Hakhano colliery,” Jacobs points out.
Design all important
The design of the Hakhano filtration plant is the same as that of the other two plants, but the material being filtered at Hakhano is raw, whereas at the other two collieries the fines are upgraded to export quality using Enprotec’s duel-cell technology before it is filtered, he explains.
Meanwhile, the success of the Hakhano filtration plant has led to Umthombo Resources considering the implementation of a similar plant at its other mines. “We are currently in the process of starting up our Phalanndwa colliery and a similar filter press will be commissioned there as well,” says Bayoglu.
Further, Enprotec is also working on five other projects, which the company aims to have in operation by the end of 2013. “One of these projects is for coal producer Stuart Coal’s colliery outside Delmas, in Mpumalanga, and we have already established the site,” Jacobs says.
Enprotec is conducting laboratory-scale test work for potential longer-term projects. “The next thing we are looking at is to make inroads into other mineral resources with our technology. We are currently doing test work in platinum and iron-ore,” Jacobs says.