FLSmidth high density thickeners optimise recoveries at DRC copper-cobalt mine
FLSmidth says it has delivered a thickener solution to help double production rates at one of the world’s largest copper and cobalt producers in the Democratic Republic of the Congo (DRC).
The order for the solution, which included six of FLSmidth’s high density thickeners, was placed in 2020, with delivery now completed.
The mine already had FLSmidth thickeners on site, with the company’s proposal for the mine’s expanded requirements based on test work to confirm the characteristics of the material to be treated, according to FLSmidth General Manager Projects and Account Sales, Howard Areington.
“The tests confirmed that we could use a similar design to what we had installed on the mine some years previously,” he says. “This solution included six counter current decantation (CCD) thickeners and one pre-leach thickener, each measuring 31 m in diameter.”
These units deliver high solids underflow to optimise the recovery of dissolved metals, according to FLSmidth. In addition to the steeper floor slope, these thickeners were designed with a high torque ring gear drive design, with high tolerances that make for minimal maintenance over long periods of time, the company says.
“Our high density thickener design ensures consistently high underflow densities which allows the operator to sustain high production rates and better recoveries,” Areington says.
These CCD thickeners are manufactured from LDX2101 duplex stainless steel. This provides mechanical benefits without compromising chemical resistance, allowing the mass of each unit to be reduced, the company explained. The pre-leach thickener, which was not exposed to corrosive conditions, is constructed from carbon steel.
“We also designed and supplied five impurities removal thickeners, which are high rate thickeners, also in LDX2101 stainless steel,” Areington says. “The sizes of these units ranged from 20 to 30 m in diameter.”
Fabrication of the equipment was carried out in South Africa while accommodating the demands of the COVID-19 lockdown, which required careful planning and flexibility. With components and platework delivered to site, the welding and construction was conducted by the mine with installation assistance from FLSmidth and its agent in the region.
