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South Africa’s metallurgical adsorption circuit specialist, Kemix, has developed a global reputation for its minerals processing equipment. While the majority of its project work is currently international, it is making its local mark on Pan African ResourcesBarberton Tailings Reclamation Plant (BTRP) project, writes Laura Cornish.

“Even though our focus as a company is global, and spreads across every continent, our interest in the local mining sector has not deteriorated and remains an important element of our overall business,” says Kemix MD, Gavin Veale.

In August 2012, the company was awarded the contract to supply its specialised equipment to the BTRP. The project will recover tailings from the historical Barberton gold mines, increasing its annual gold production capacity from about 95 000 ozpa to 115 000 ozpa.

“Our contract includes the supply of nine MSP 500(P )pumping interstage screens and 18 launder gate valves for the carbon-in-leach(CIL) circuit, along with a 250 kg/h electric carbon regeneration kiln and two 8-cathode/9-anode electrowinning cells,” says Kemix metallurgist Mark Proudfoot.

“Considering the BTRP project will process some of South Africa’s oldest tailings material, we are very proud to be involved in the project. It also means we have local project work in addition to our extensive international business,” Kemix marketing director, John Rogans notes.

Kemix also assisted engineering contractor Basil Read Matomo with certain aspects of the adsorption circuit launder layout. “We have already supplied all of our equipment to site,” Rogans continues.

The Kemix equipment range is ideally suited to the optimal adsorption of gold, making it ideal for Barberton’s gold tailings recovery plant. Mineral processseparating pumping (MPS(P)) interstage screen technology is designed for CIL circuits having the tanks and operating pulp levelsat the same horizontal elevation. The pumping action of the impeller induces sufficient head and pulp velocity to transport the pulp to the next adsorption tank in the circuit.

The Kemix launder gate valves are designed for open launder circuits primarily in gold adsorption circuits. They are manufactured to suit the launder dimensions for specific applications and can be supplied either as manual or automated units.

The Kemix carbon regeneration kiln is custom designed to meet application requirements, with regard to mode of firing, voltage, frequency and throughput. The kiln’s retort tube is manufactured from specialised alloys capable of withstanding high temperatures associated with thermal regeneration. The design of the retort tube with consideration to peripheral speed ensures carbon bed turnover, thus enhancing the complete thermal regeneration of the carbon. All Kemix kilns have an automatic start up and shut down sequence, which reduces operator input. Speed variation of the screw feeder facilitates greater flexibility and complete plant integration.

Gold or silver bearing solutions from an elution process or high-intensity concentrate leaching system are suitable for treatment in a Kemix electrowinning cells. It is engineered as a non-complex, robust and easy to operate unit with minimal maintenance requirements. The electrowinning cell consists of a sandwich arrangement of anode assemblies on either side of cathode compartments, all contained in a tank manufactured from 316 L stainless steel.

Kemix also supplies pumpcell technology, which is in essence a complete carbon-in-pulp (CIP) circuit, incorporating a pumpcell mechanism and launder system enabling the carousel mode of operation to be employed. The design of the pumpcell circuit allows all contactors to be placed at the same horizontal evaluation, in contrast to the stepped arrangement used for conventional cascade CIP adsorption plants. This feature facilitates the carousel mode of operation, where the pulp feed and tailings discharge positions are rotated in such a manner that a counter current movement of pulp and carbon is achieved without the need to physically move carbon from one pumpcell to another. The carousel mode of operation has been shown to result in significant improvements in adsorption efficiency, due to the elimination of ‘backmixing’ inherent in the conventional CIP circuits.

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