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:: DRA Undertakes R40 Million Blyvooruitzicht Contract
DRA has undertaken a R40 million contract for Durban Deepís Blyvooruitzicht gold mine, which is located 5.0 km south of Carletonville and 75 km southwest of Johannesburg, as part of a project to reclaim the mineís No 4 and 5 tailings dams.
The tailings deposits, dating back to the 1940s, consist of about 25 million tonnes of ore at a grade of 0.587 g/t gold. The plant to process these will be on stream in October 2003 with full operational capacity to be achieved by the end of the year after a build up period of about two months.
Feasibility work on this fast-track project began in April 2003 and the decision to begin implementation was taken in May. This will see the removal of the mine dump closest to Carltonville. The tailings will be transported using a pipeline for about 5.0 km to the plant, and after processing, another 7.5 km to the current tailings dam.
The project has been fast tracked as rock dumps at the mine are being depleted at a faster than initially planned rate and the ore from these tailings will provide a new source of feed for the mineís plant to compensate for this. Fraser Alexander, which has the Build Own and Operate contract for the mining of these tailings will supply the high pressure water for the required monitoring equipment, as well as screens and pumps to enable the transfer of the tailings to the processing plant.
DRA process consultant, Bruce Ebell says that the project will use existing equipment at Blyvooruitzicht, including the old transfer pump station, though new transfer pumps will be installed at the reclamation site, which will be upgraded to handle a higher tonnage. The existing residue pumps will be released for deployment at the reclamation site and DRA will install a new pipeline. When the project is concluded the reclamation of the tailings will take place at a rate of 240,000 tonnes a month.
Eight tanks in a hybrid two-stage carousel/carbon-in-leach (CIL) plant will process the recycled tailings material. One of the eight tanks will be converted into a pre-conditioning tank where lime and oxygen will be added and the other seven will be converted to CIL tanks through the installation of interstage screens and agitators. High shear reactors are being used for the addition of lime, oxygen and cyanide, to improve the kinetics of the dissolution of the gold, and reduce the consumption of reagents. Loaded carbon will be sent to the existing elution plant for gold recovery.
The residue from these tanks will be pumped to the existing gold plant, and will be joined by the run-of-mine material of 120,000 tonnes a month to take the total material processed to 360,000 tonnes a month compared with the current 210,000 tonnes a month. The reagents will use the existing cyanide storage and dosing facility.
The project will also see modifications made to the tailings dam, and the dam wall will be changed from a day wall to a cyclone system. Return water from the tailings dam will be pumped back to the reclamation site over a distance of 6.0 km for reuse as high pressure water.
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