Environmental consulting firm Golder, a member of WSP in Africa, says a holistic approach to water management is essential to achieve resource sustainability.
With rising competition for water access, mines must not only reduce their water consumption but also – and more importantly – focus on extending the life cycle of mine water through environmental planning.
The firm promotes strong external water governance to identify, manage and regularly review water-related risks. In considering the law of the circular economy, which promotes the recovery of resources from waste, the firm aims to reduce, reuse and recycle water throughout the mine’s life cycle.
“We assess mine water using the mine life-cycle approach, which aims to assess the environmental impact [on] all stages of the mine’s life, from cradle to grave,” claims Golder Africa MD Ralph Heath.
Finding suitable long-term solutions is essential, he continues. The sooner a mine’s closure implications are fully assessed the sooner water strategies implemented during operational periods can be adapted to minimise post-closure costs and legal liabilities, which can far outstrip operational adaptation costs, says Golder water treatment lead Peter Wille.
The life-cycle approach is the key tool in implementing effective environmental planning throughout the processes to optimise and minimise water consumption, consequently ensuring that mines comply consistently with water regulations.
Analysing current water use, rainfall and demand enables the firm to optimise solutions for a mine. Improving the reuse of water and abiding by the water-use licence enables mines to maximise the natural value of the South African environment and resources through the Catchment Based Approach, or CaBA –an inclusive, civil society-led initiative that works in partnership with government, local authorities, water companies and businesses.
Wille comments that the firm generally “assists mines that have committed to the International Council on Mining and Metals’ (ICMM’s) water-reduction targets”.
He explains that ICMM’s water stewardship framework outlines a standardised approach to water stewardship for the mining and metals industries, acknowledging that water connects an operation to the surrounding landscape and communities.
Companies assisted by the firm are setting ambitious targets aimed at achieving action that is positive for businesses and communities, as well as the environment in which they operate.
“Global progress has been made with initiatives such as the ICMM raw water savings targets, which are becoming imperatives in mines and is an approach we always take into account when advising clients,” says Heath.
Further, mining is the only industry in the Carbon Disclosure Project’s ‘2019 Global water report’ that routinely monitors and discloses its impact on water quality. The report covers water balance, quality-related company risks, impacts and interactions with water, which are mandatory requirements for membership of the ICMM. This serves as proof of the industry’s commitment to use water in a responsible and sustainable manner and that water conservation and water demand management are not just catch phrases towards which lip service is paid, says Wille.
The ongoing developments in passive water treatment technologies to support mine closure make it an exciting growth field, Wille enthuses.
Passive Water Treatment
Passive technologies or treatments are defined as those that do not use – or use few – chemicals or mechanical equipment –to clean mine-impacted water, making the progress more economical and less harmful to the environment .
Golder has worked with the South African mining industry and the regulators to develop passive treatment over the past two decades. “Currently we are working with Thungela (previously known as Anglo Coal) on a pilot scale project. We have also received global support to further develop aspects with colleagues globally and at Thungela,” states Heath.
The intention is to implement technology that requires reduced operator input and, ideally, no power consumption. Passive water treatment can then be integrated with sustainable land use developments, such as agriculture and agroforestry, to provide a more sustainable closure solution, benefiting communities post-closure.
A typical technology developed in South Africa for mines is the degrading Packed Bed Reactor technology for biological sulphate reduction. The technology uses a bed (reactor) packed with suitable organic matter, Wille explains.
The mine water decant is then routed through the bed and anaerobic bacteria reduces the sulphate to sulphides. This is then either deposited as metal sulphides or in the absence of metals, will remain in the water as hydrogen sulphide which can then be oxidised to elemental sulphur in the next treatment step.
The passive water treatment is complementary to the life-cycle approach because once the mine closes, the functionality and value of the water resumes as a resource, which can be used in a different sector thereafter, he claims.
In addition, Golder Associated North America has developed a report on selenium removal from mine water decant for the North American Metals Council and is demonstrating the associated passive treatment technology, Ralph concludes.