Water Journal : Water Journal June 2014
JUNE 2014 WATER 41 Workshop Reports MEMBRANES IN MINING: IDENTIFYING SOLUTIONS TO IMPROVE QUALITY AND SOLVE AUSTRALIA'S UNIQUE PROBLEMS Report by Diane Wiesner Dr Mike Dixon from Nano H2O chaired this workshop and began by brie y alluding to one of the most pressing challenges to water professionals working with the mining industry: the need for treatment of coal seam gas (CSG) water. He identi ed membranes as the key technology to be used to remediate this produced water and some of the current challenges and weakness in existing mining technology. The CSG issues serve as an example of the growing need for more innovative thinking and applied research as Australia seeks to further exploit its mineral and gas resources without destroying the country's fragile environment. Neil Palmer, CEO of National Centre of Excellence in Desalination (NCEDA), spoke rst by summarising some of his Centre's funded research projects with particular application to problems encountered in the mining sector and the remote, arid environments where these are sited. A number of these addressed the problems of nding bene cial reuse schemes for receiving treated water resulting from coal, CSG and other mining activities. These range from forestry to citrus agriculture, to alumina production and turf growing. Professor Stephen Gray from Victoria University covered the research activities conducted by his team, with a focus on some of the problems arising from using water or producing it during mining. In mining, the wastewater produced frequently contains lot of hard, particulate material that tears and damages membranes, plant and pipework. Groundwater, often available in arid environments, is frequently limited in quantity and very variable in quality. A high level of silica is common. Recovery is optimised by operating at low pH, which increases the solubility of silica, resulting in improved recovery. Where the water is going to be acidi ed anyway -- for example, acid leaching in gold mining -- this approach is very useful, especially where groundwater is not highly buffered. Other research with potential application to mining industries includes brine management using ceramic membranes that are longer-lasting than polyamid-based ones and more resistant to acid cleaning and particulate attack. Membrane distillation using waste heat generated on site and for solvent extraction, diffusion analysis and electrodialysis is also under investigation. Rob Heilbronn, an experienced hands-on engineer who is used to troubleshooting problems on site at mines across Australia and beyond, then described three separate brown eld operations where he had worked, all with problems where simple adjustments greatly improved their processes. In the course of his talk, Heilbronn provided some invaluable insights to working in the resources sector: • Mining companies tend to underestimate the complexity of water chemistry and often only consider water at the end of the design phase, because water is not assumed to involve huge expense in the context of their massive project expenditures. They also assume that, because the water may appear clear and blue, it is pure and good; • Project design may be assigned 20% of total project time, but it is essential to get the water process and operational criteria optimised at the design phase because casual or inappropriate plant will impact on end costs and operational performance. There must be good characterisation of water quantity and quality at this stage, not later; • Once halfway through a project, there will usually be an opportunity to pilot test or make adjustments to improve operations -- especially if the design criteria are not being met in the eld. The solution to an underperforming plant may simply be a step-by-step review of all stages to achieve an improvement in treatment plant performance. Heilbronn concluded his informative talk by providing examples of these scenarios from his work in a gold mine, in an antimony plant and in a WA nickel mine. Hiep Le, Senior Wastewater Engineer from Osmo o, gave the nal presentation to the workshop. He focused on the challenges he usually faced in his work at mine sites in Australia and overseas. They centre on the nature of the water source (not always readily available, as in Chile), fouling and scaling, and clients who tend to be very conservative and uninterested in embarking on potential innovative approaches to problems. The workshop then broke into cross-disciplinary groups tasked with identifying new directions for investigation that will assist the industry in optimising water strategies. This was a well-attended workshop with interactive and interested participants. Left to right: Neil Palmer with Operations Managers from ve of the 'Big Six' Australian desalination plants: Chris Young (Perth SDP), Grieg Mercer (Victorian DP), Tom Ransome (Perth Southern SDP), Guillermo Hijos (Adelaide DP) and Scott Murphy (Gold Coast DP) at Ozwater14.
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