New generation water solutions: sustainable use of water

Author Sonja Kuokkanen, Trainee, MP R&D and strategy 

UN Global Compact SDGs: Ensure availability and sustainable management of water and sanitation for all (UN, 2019) Outotec is also supporting this UN Global Compact SDG 6.

Water is an essential resource for the mining industry. In minerals and metals processing water is used from seas, rivers, lakes and even groundwater. The level of water consumed is case-specific and varies greatly depending on factors such as climate, water quality, geology, ore mineralogy, mine management and practices, and the commodity being processed. However, water is a scarce resource in many parts of the world where the industry operates. Also decreasing ore grades mean that it is becoming necessary to extract higher volumes of ore to generate the same amount of refined product. In general, the lower the ore grade, the more water-intensive the processes to extract the ore will be.

There’s increasing pressure to decrease the amount of freshwater use in the mining industry

Kari Heiskanen, Technology Director at Outotec, has wide experience in water-related issues in the mining industry and works with the development of new sustainable water solutions. On a local level, the Minerals and metals industry can have a major impact on water consumption. However, on a global level, its impacts are small when compared for example to agriculture.

"We are trying to reduce the impacts of mining on local communities. Minerals and metals processing requires approximately 4 cubic meters of water per ton of ore. In theory, it is possible to decrease freshwater intake to 0,2 cubic meters of water per ton of ore. However, this means that the remaining 3,8 cubic meters of water required, must come from recycled process water,’’ says Heiskanen.

The socio-political impacts of water use have also created pressure to use water more efficiently in the mining industry. Achieving a social license to operate is critical for mining companies. Also, laws and environmental permits which restrict the use of water are tightening.

"Mining companies have begun to realize that wastewater and polluting water is not socially acceptable. Therefore, there are many countries where freshwater use is restricted and in most countries, water usage is already regulated,’’ Heiskanen adds.

Outotec is developing new generation water management solutions

New water management and tailings solutions decrease the overall usage of process water and enable the use of different water sources. In addition to freshwater, surface water or groundwater, new solutions can use salt water or even urban wastewater. Outotec develops technologies that enable the recycling of water, as we believe that it is the solution for sustainable water usage in the future.

"We are developing solutions that enable totally closed water circles. It means that the only amount of freshwater which is withdrawn to the process is water that replaces water which is evaporated to the sky and withdrawn through products," Heiskanen explains.

New-generation water management solutions recycle the process water before it enters the tailings ponds, increasing water recovery and hence decreasing the need for freshwater intake. However, the shortening of the water recycling process has some side effects regarding the quality of water.

"Temperature rises when the water cycle time is reduced. Then conventional chemical and biological reactions that used to happen in the tailing’s ponds have no time to proceed. This combined with the related microbiology changes makes the water very unstable and hard to manage. Developing solutions that enable managing water quality are needed to recycle water,’’ Heiskanen says.

One of the new water management solutions is Pretium Water Advisor, previously called as WQQM. WQQM has been commercialized within the SERENE project which is funded by EIT RawMaterials. It is a new IIoT-based water management system that helps the mining industry monitor the entire mine site’s water balance in real-time. The system also provides the industry with the possibility to create short-term forecasts for the site’s water volumes and water quality in different production and environmental conditions. It has been developed as a response to the common water management challenges in the mining industry. Such challenges are pressure to increase water recycling, fulfill environmental regulations and decrease effluent generation, minimize production losses and avoid product quality problems due to poor and fluctuating water quality.

 

PWA is a holistic water management solution, which monitors the mine site’s water balance in real-time.

The objectives of WQQM solution are in line with the thinking in which water is circulated inside the production process. Kari explains that in order to do so, there needs to be a new kind of thinking of water use in the mining industry:

"The idea is to turn around the thinking that water is purified in the end of the pipeline. Instead, water can be used from various sources, and the quality is modified according to the needs of the process stage. This way we can create a business concept which brings added value to the customer,’’ Heiskanen explains.

Future holds for more sustainable mining

During the past decade or so there has been increasing pressure to decrease the amount of freshwater usage in mining/minerals and metals processing. The factors driving the change are:

  • Freshwater is one of the world’s most precious commodities being literally lifeline for all of us. Increased efficiency of utilization of water does not just generate major cost savings but affects the environment of vast areas around the mine sites.
  • Storing water on the mining site comes with major environmental risk, which is also a financial risk to the mining company. For example, impacts of a tailings dam leakage would be a financial as well as a natural catastrophe.
  • Many mines are in areas where water is scarce. This means mines are sharing the scarce water with the local communities’ needs. Sociopolitical issues might provoke rejection of mining licenses.
  • As ore grades decrease the volumes of extracted ore become larger. New technologies are needed to manage the larger tailings amounts with less water than before. Large amounts of tailings water on-site can cause problems in the quality and management of the water as it becomes connected to the hydrological ecosystem.

Read more about the OUTOTEC® PRETIUM WATER ADVISOR