A Limpopo chromite mine faced various risks in disposing of its tailings and called Multotec for a solution. The chromite operation was aware of the challenges that a traditional tailings storage facility (TSF) could create, according to Multotec Process Equipment senior process engineer Khathutshelo Mutshinyalo. These include the large footprint of a tailings dam, the expense of lining the tailings dam and the environmental and social impacts.

“The mine management was keen to conserve scarce water resources by avoiding evaporation,” Mutshinyalo says. “They also wanted to prevent any potential groundwater contamination that might result from solution seepage. There was also the local community to consider, to which a normal TSF could present a risk.” Multotec was able to explore the full range of its dewatering solutions before recommending the most suitable one for this application, he says.

The filter press technology was the chosen option, as it was shown to meet the duty requirements in the most cost effective manner. As a well-proven mechanical dewatering strategy, the filter press was able to immediately recover about 80% of the clean water in the slurry. “The cake that is left from the tailings after water removal is then easily moved by conveyor to a dump area,” Mutshinyalo explains. “This dump is much simpler and safer to manage than a tailings dam.”

The solution facilitates short cycle times, less wear on consumables and lower power consumption. The cakes are also easily released from the cloth and leave little residue behind on the cloth. He highlights that the process of reaching the selected solution was driven by thorough investigation, extensive test work, and many years of experience in the field. It always begins with a detailed understanding of the conditions that exist at the site, as well as the customer’s priorities.

“With the support of the research team at our testing facilities in Spartan, we were able to test the behaviour of the customer’s slurry samples with various Multotec solutions,” Mutshinyalo says. “This allowed us to confirm not only the best technology for the application, but also to innovate our equipment for optimal results.”

In this case, the abrasive impact of the tailings material was one of the key factors to be accommodated. While the filter press was proven to be the most effective solution, there was still considerable wear experienced by the filter cloth in the press.

“Combining our field experience and metallurgical expertise, we looked more closely at possible innovations for this aspect of the equipment,” he says. “We developed an improvement that would better protect the high-wearing areas of the filter cloth and deliver longer wear life.”

The detailed preparation behind this solution, and Multotec’s practical expertise in installing and maintaining its equipment, meant that final commissioning on site could be done without delay.

Posted by Paul Moore on 14th February 2020 

SOURCE INTERNATIONAL MINING

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• Mining Development