Water management in mining industry

  • The mining industry heavily relies on water
  • Preserving water quality and quantity in mining is critical for uninterrupted operations
  • Sustainable water management in mining can be started by choosing sustainable solution in treating mine water

All human activity depends on the availability of water. From basic survival to the most complex and innovative industries, it is a resource whose quality and quantity affects the well-being of every person, business, and nation. However, water, especially of the quality needed for human society, is not unlimited. Which is where water management comes into play. And like all industries, the mining industry has the duty of using water in a responsible and sustainable way.

The role of water in the mining industry

Water is both critical to the profitability of the mining industry and used up and polluted in large quantities as part of this process when done unsustainably, harming local communities and habitats. This means that the mining industry has a triple imperative for more sustainable water management, driven by economic, environmental, and social needs.

The Carbon Development Project (CDP) study, conducted on behalf of 530 investors representing $57 trillion in assets and published in July 2013, indicated that 64% of mining industry respondents had experienced negative water-related business consequences in the previous five years.

In the mining operations, water is primarily used in at least three key processes.

Mineral processing uses water in industrial quantities for quarrying, milling of mined materials, injection of water for secondary oil recovery or for unconventional oil and gas recovery (such as hydraulic fracturing), and other associated operations. Several economically relevant materials require water for extraction, including coal, iron, sand, gravel, crude petroleum and natural gas. Moreover, water is needed for the cooling of machinery, for centrifugal separation and for chemical processing.

Wet dust control systems require vast quantities of water. These systems use spray nozzles either to apply water at the dust source and prevent the dust from becoming airborne in the first place or to target the airborne dust particles to suppress and minimize the distance the dust travels. Whether during mineral processing, at waste dumps or on haul roads, dust control is vital for minimizing health and safety risks, as well as for lowering impact on the environment.

Transportation is typically the biggest water demand of a mine. The ore is crushed and suspended in an aqueous slurry, which is then pumped through a pipeline to the processing plant. While using more water than conventional transportation methods such as trucks or trains, this method is a lot more energy efficient and economically viable.

Depending on how it is used, water is categorized into raw water, supplied from precipitation, groundwater, rivers, and lakes and used for employee needs, process make-up water, shaft and underground mine water demand, mobile fleet washing, fire water, etc.; compliant flow (non-contact water) that’s compliant with environmental legislation and can be directly released in the environment without treatment; and non-compliant flow (contact water) that has had contact with mining, mineral processing, and tailings disposal and, as such, is not suitable for direct release into the environment. To improve water use efficiency, non-compliant flow is usually collected and reused on-site to the maximum extent and then treated as necessary.

To sum it up, without adequate amounts of water available, many minerals cannot be extracted to begin with. Access to water is then needed for the safe and efficient use of industrial machinery and to lower human health risks, and improves the profitability of deposits, especially remote ones that do not have access to roads or rail infrastructure.

Challenges to water management

The challenges encountered while trying to supply water for a mining operation will depend on a regional basis. In dry climates like the southwestern United States, northern Chile, southern Peru, and northern Africa, the key issue is low water availability. The deficit must be met through efficient water management focused on water conservation and reuse. In wet regions like Colombia, Indonesia, and New Caledonia, the obstacles include flood events, which can result in spilling events, erosion, and infrastructure failure. Lastly, operations in cold climates like Canada, Russia, and Finland must consider the water resulting from snow melt and ice thaw due to mining activity, ensuring appropriate drainage is possible without impacting the environment or the extraction activity. Unsustainable use can have catastrophic consequences on humans and the living world.

Events such as the Baia Mare cyanide spill destroy ecosystems, create high costs due to environmental lawsuits, and lower public trust in mining. 100,000 tons of cyanide-contaminated water was released when a reservoir broke, releasing them into the local rivers Someş, Tisza, and Danube, wiping out up to 80% of the aquatic life within the affected regions and contaminating the drinking water of over 2.5 million people. This is why each individual mine must develop a holistic, integrated approach to water management.

Methods to improve the water use efficiency

As pressures to improve efficiency and reduce the environmental impacts of mining grew, several methods and technologies were developed to facilitate better water use, and ensure profitability and compliance with environmental norms. These new approaches include but are not limited to: limiting the volume of water required for mining operations, using lower quality, alternative sources of water such as seawater when possible, treating mining water for reuse, and protecting the quality of water discharged after use.

Suitable methods are necessary to both ensure water availability and avoid excessive use of chemicals, which may risk breaking environmental compliance. One way to capture non-compliant flow for reuse and treatment is through tailing dams. However, the high pH and salinity frequently give rise to algal blooms, which can clog filters and make water reuse significantly slower and more expensive. Copper sulphate can be used to prevent algal growth but has severe environmental impacts and is not always compliant with regulations. Manual removal and cleaning are costly, labor-intensive, and time-consuming, slowing down extraction and lowering profits.

Sustainable solution

Chemicals won’t be a sustainable solution for the mining industry as they will risk environmental compliance. At LG Sonic, we developed MPC-Buoy, an innovative, environmentally friendly solution to algal growth that can be deployed to improve water use in mines. LG Sonic’s ultrasound technology only targets algae growth, leaving other aquatic life unharmed and preventing algal toxins from being released. The system can prevent algal blooms by using real-time water quality monitoring, allowing for business as usual while conserving water and saving time and money. Real-life experience from Vale in Brazil and Masbate Gold Project in the Philippines proves the efficiency of this technology, with satisfied clients and minimal environmental impacts on the mining industry. This technology is one of the many steps that can take us toward a future where mining provides us with vital minerals without straining water supplies or putting pressure on local ecosystems.