Cradle to grave
Refurbishment not a sweat
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to Philip Hoff , managing director at MIP Process Technologies , many South African minerals-processing plants contain outdated equipment that can be revitalised at minimal cost .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 mineralsprocessing staple that lends itself to refurbishment as opposed to replacement .
MIP Process Technologies managing director , Philip Hoff .
MIP Process Technologies
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 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 , 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 heating or cooling is not required , cycle time can be short
[ 34 ] MINING MIRROR MAY 2018