Water plays an integral part in virtually all mining operations and consequently the importance of carefully managing it has been long understood by the industry. Dr Richard Coulton reports.
Water is expensive to pump and treat. In arid regions such as Australia its conservation is critical in ensuring the financial viability of the mine and as result techniques such as paste tailing disposal have been developed to minimise evaporative losses. In less arid regions, the problem is not one of water conservation but the disposal of excess water. In these regions the adoption of measures to minimise inflow is the first line of defence, but where this not possible the only option is pumping and disposal off site in an environmentally acceptable manner.
In these less arid environments the industry is faced with the challenge of balancing the cost of water treatment with ever tighter discharge standards. Historically these standards focused on toxic heavy metals (such as cadmium, lead and zinc) but now also include iron, manganese, sulphate and chlorides.
While the regulator’s principal concern is the quality of the water discharged off site, the mine operator has to take a more holistic view taking into account the capital cost and on-going cost of reagents, power, manning and sludge disposal.
On large mine water treatment projects, the least costly solution invariably involves the construction of a bespoke water treatment tailor to the site specific water chemistry and flow rate.
However on smaller projects the use of containerised packaged water treatment plants can provide the least cost solution, particular for those projects where time is of the essence.
Siltbuster Process Solutions (SPS) has recently developed such a solution. It was approached by UK-based mining consultants SRK who were working on behalf of Canadian-based Global Minerals to provide a treatment plant to allow the reopening of the Bana Maria mine near Roznava Maria in eastern Slovakia.
Recent diamond drilling undertaken on behalf of Global Minerals had identified additional silver and copper reserves that had not been exploited before the state owned mine was closed and allowed to flood. Based on these results Global Minerals were keen commence mining as soon as possible. However to do this Global Minerals needed to pump and treat over one million cubic metres of mine water contaminated with up to 270mg/l of dissolved iron and 90mg/l of dissolved manganese.
As the dissolved metal concentrations were relatively high, we recommended of a high density sludge plant and designed a modular plant based on the dimensions of a standard 20ft high-cube shipping container. This enabled us to build and test the plant in the UK before dispatching it to Slovakia on six articulated lorries. Once on site the plant was installed, tested and commissioned within a month.
By adopting this approach the whole process from contact award to commissioning the plant took less than 5 months to complete.
Since commissioning in February 2012 the plant has successfully treated 700,000m3 of water removed in excess of 600 tonnes of heavy metals allowing Global Minerals access back into the existing workings from which they can drive new cross cuts to allow further exploration and eventually exploitation of the additional reserves.
Dr Richard Coulton is CEO Siltbuster Ltd, Monmouth, Monmouthshire, UK. For more information, visit www.siltbuster.com