IM 2021 March 21 | Page 51

WATER MANAGEMENT plants have been installed in NSW for to further reduce volumes of concentrate from reverse osmosis desalination of coal seam gas produced formation water and at a uranium mine in NT .
Membrane free desalination from Clean TeQ Water
Clean TeQ Water ’ s CIF ® ( Continuous Ionic Filtration ) technology uses both chemistry and filtration to remove pollutants from water . Unlike typical ion exchange ( IX ), CIF uses a moving packed bed of ion exchange resin , which provides continuous and targeted removal of contaminants while also removing suspended solids .
DESALX consists of two CIF modules in series , first removing multivalent cations ( such as calcium , magnesium , and metals such as manganese and iron ), and then multivalent anions ( such as sulphate ). During the treatment process , monovalent ions such as sodium and chloride pass through , and a gypsum-based brine is created which can be sent to existing lime precipitation systems for a zero liquid discharge solution .
By moving the resin around the system , DESALX can tolerate the precipitation which occurs during desorption , allowing cheaper reagents such as sulphuric acid and lime to be used . DESALX ® has a typical OPEX of $ 0.40-
0.80 / m 3 and typically achieves between 90 and 100 % water recovery .
“ There is huge potential for applying DESALX at mine sites globally ” said Willem Vriesendorp , Clean TeQ Water ’ s General Manager . “ Environmental discharge restrictions for hardness , metals , and sulphate are becoming increasingly strict , and these are commonly present in mining wastewater as a result of processing , acid mine drainage , or using sulphuric acid on site . DESALX is an innovative and robust water treatment process which provides a cost effective , zero liquid discharge alternative to membrane treatment .”
Clean TeQ Water designed , installed , and commissioned a 2 ML / d DESALX plant in 2018 at the Fosterville Gold Mine in Australia , which has been running continuously since commission with no major stoppages . The mine had an excess of water from dewatering underground mines , which required treatment to a level suitable for aquifer reinjection . Antimony and arsenic are first reduced using precipitation , before DESALX removes calcium , magnesium , iron , manganese , and sulphate to the required level . The DESALX effluent can also proceed to the reverse osmosis plant on site , which further treats the water for reuse . Higher recovery and longer membrane life are achieved by the RO , as the species that scale or foul membranes are greatly reduced . When water reuse isn ’ t required , water is suitable to be reinjected into the aquifer directly after Clean TeQ ’ s DESALX plant , minimising the treatment cost and avoiding saline brine disposal issues which arise from reverse osmosis treatment .
The role of filtration and thickening
IM also caught up with senior managers at two global giants in mineral processing equipment , FLSmidth and Metso Outotec , to get the lowdown on the role of filtration and thickening processes in water saving and management .
On whether there is greater interest in large tonnage filtration solutions and dry stack solutions in mining , FLSmidth Director of Tailings Solutions , Todd Wisdom comments : “ I would say every project nowadays is evaluating the benefits of filtered tailings . In most cases , the desired geotechnical cake moistures needed require pressure filtration . The majority of projects that are seriously considering filtered tailings however , are still less than 25,000 t per day of tailings production – my feeling is that larger tailings tonnages are still a little bit away from being implemented . We have addressed this market need with our new AFP2525 Filter Press , featuring leading-edge technology , which uses high pressure and low cycle times to achieve significantly larger single-machine capacities compared to other filter types .”
FLSmidth says its new AFP2525 has a unique

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