Mining Mirror May 2018 - Page 36

Cradle to grave There is an increasing trend in the minerals-processing industry to ‘sweat’ mining assets. According to Philip Hoff, managing director at MIP Process Technologies, many South African minerals-processing plants contain outdated equipment that can be revitalised at minimal cost. “Better throughputs and higher efficiencies can be achieved reliably with newer technology,” says Hoff. The recent modernisation of thickeners at a South African phosphate mine resulted in much higher and consistent underflow densities. In addition, subsequent downstream process efficiencies such as filtration have also been improved. An added benefit is a substantial saving in water, which is an increasingly scarce resource. Hoff says MIP Process Technologies has also recently refurbished two 45.7m-diameter thickener mechanisms for a gold operation. “Thickeners that have been dormant for years can now be put back in operation at minimal investment. This enables the mining operation in question to increase productivity and remain economically viable,” says Hoff. Hoff adds that linear screens are another minerals- processing staple that lends itself to refurbishment as opposed to replacement. MIP Process Technologies managing director, Philip Hoff. Oxygen enables metallurgist to take a breath Understanding oxygen demand is critical to optimise metallurgical gold leach optimisation. According to Rob de Zoeten, metallurgist at Afrox, accurately establishing the total oxygen requirement is often overlooked. “In many cases, undersized on-site oxygen plants are installed that cannot produce sufficient oxygen to optimise the leach,” says De Zoeten. Afrox has developed a unique and fully integrated end-to-end product service offering (PSO) for the global gold mining industry to optimise metallurgical gold leach using oxygen. The PSO, called Goldox, provides an oxygen demand test programme [34] MINING MIRROR MAY 2018 for specifying the oxygen demand requirements; the supply of oxygen using Linde Engineering’s proprietary on site vacuum pressure swing adsorption (VPSA) technology; supply, install, and commissioning of the oxygen reticulation network, flow control panels with safety interlocks and the oxygen injection system; ongoing maintenance and downstream oxygen control management if required; and provision of a highly flexible commercial structure for the supply of oxygen to the mine over an agreed period. The Linde Group generates low-purity (90–95%) oxygen, which is proven to be ideal for gold leaching, Refurbishment not a sweat through the use of its VPSA technology. As a member of the Linde Group, Afrox can provide accurate guidance to gold mines regarding their oxygen requirements for both new and existing leach plants. VPSA is an ambient temperature technology that takes advantage of the different binding capabilities of various gas molecules to a solid, porous material such as zeolites. The VPSA processes cycles between adsorption and desorption of impurities as the feed gas flows through adsorber vessels to produce a continuous high-purity product gas. Since X][܈[š\\]Z\Y XH[YH[Hܝ