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Paul O’Callaghan is CEO of Bluetech Research. The article is based on the report: Wastewater Treatment in Mining Metals.
Water access challenges and new mining discharge regulations are creating opportunities for the application of new water technologies. Yet the size and complexity of operations and cost of treating mining wastewater has slowed innovation. Which technologies/companies are emerging as successful?
As with many industrial sectors, the treatment of wastewater in mining applications is a secondary consideration tied to environmental policy and regulation, rather than a core operating practice.
As a result, many operators focus on well understood processes that require significant civil work, such as lime softening, tailings storage and chemical precipitation to be used as the primary system applied for heavy metals removal. However, in some instances novel and innovative technologies have been adopted with beneficial results.
There are several drivers leading to adoption of more advanced treatment technology, including:
- In Chile, increased water scarcity is leading to the adoption of desalination for supply
- Reductions in allowable discharge limit for selenium from Canadian mines
- Need for mining companies to protect local environments from contamination and maintain a social license to operate
- Declining investments in mining related projects and increased operational cost are driving a need to make existing projects more cost effective.
Desalination drive in Chile
According to a recent study by Moody’s Investor service, approximately two thirds of mining operations for the six largest hard rock mining companies are located in water stressed regions of the world. Water risk and scarcity in mining are increasingly areas of concerns for the industry and have driven investigations into the application of advanced treatment solutions.
For example, decreasing water resource availability has pressured the Chilean government to prioritise domestic access over the mining industry. This is particularly apparent in the Atacama Desert, where mining projects need to ship desalinated seawater several hundred kilometers from the coast to supply operations with water (figure 2 shows current planned and installed desalination capacity for nine facilities).
Despite these considerable costs, desalination is expected to grow as a percentage of mining water supply, driven by legislation such as a proposal aimed at making desalination more mainstream for mining operations. This would require projects with water demand greater than 12,500 m3/day being solely supplied by desalination.
Canada – selenium removal solutions
Selenium – a metalloid present in trace amounts in mine waste – has gained increased regulatory attention due to its toxic effect on aquatic environments.
The mining industry in Canada has been watching the development of new Canadian selenium regulations, due to its prevalence in many ore types. Recent estimates indicate that significant quantities of selenium in 10-25% of Canadian mine sites may require mining operations to manage seleniumin wastewater.
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