A new low energy mine water treatment plant promises a 50% reduction in the electricity costs of treating mine water. The plant has been built and tested at an abandoned tin mine in Cornwall, U.K., by the University of Exeter’s Camborne School of Mines and Minus Engineering, a U.K. engineering and consulting firm. 

NeutraSeal, the technology used in the new plant, is claimed to be able to handle high volumes of water and remove a wide range of contaminants, including manganese and sulphate, which have the potential to contaminate drinking water supplies.

The plant, built with a capacity to treat 72 m3/day of acid mine water, has a modular, scalable design that reduces capital costs by 30% compared to conventional systems. The technology harnesses the static head of water to replace pumping costs and introduces optimized neutralization and aeration processes.

The sealed nature of the system increases its reliability in extreme environments, and valuable metals can be recovered from suitable waters to provide a revenue stream.

Dr. Ben Williamson from Camborne School of Mines said, “Not only does this new water treatment technique offer lower operational costs because of reduced electricity use, it also offers lower initial capital costs. These cost savings, along with the opportunity to generate additional revenue from recovered metals, are sure to be of interest to the mining industry and we are now investigating routes for commercialization.”

Williamson and Terrie Sawyer from Camborne School of Mines worked with Minus Engineering to pioneer and test the plant at Mount Wellington mine in Cornwall. 

Interested parties from within the mining sector are invited to see a demonstration of the energy and water treatment performance of the pilot plant. 

The project was funded by the Technology Strategy Board, a U.K. innovation agency.

In a similar vein, Scalada Holdings Ltd., a Singapore-based company, recently announced its intention to investigate a new way to treat wastewater from mining. The treatment solution makes use of hydrotalcites to tackle the complexities of lime-based methods and offers a more water efficient process.

According to the company, aluminum and magnesium layered minerals, called hydrotalcites, start to form when magnesium and aluminum exist in the correct ratios during the neutralization of acidic waters. When hydrotalcites begin to form, they can decontaminate water at the same time, trapping the solid contaminants and enabling them to be removed from the wastewater as a sludge by centrifugation.

Scalada Holdings said it hopes to test the efficiency of this process in the coming months. Its CEO, Manly Logan, said, “Mining wastewater already holds high magnesium and aluminum concentrations. Hydrotalcites can be created by simply adjusting the ratio of pollutants that already exist in the mining wastewater, and adding alkaline compounds to alter the pH level as required.”

One of the potential advantages of this new method of decontamination is the significantly lowered consumption of water. Once decontaminated, wastewater can be reused by the process plant, thereby reducing the costs of water used in mining operations.

“With the potential technical advantages and added benefits of using hydrotalcites, there’s a strong possibility of the mining industry implementing this technology when it becomes commercially viable,” Logan said.

Scalada Holdings also said it had recently completed the second generation of its patented Elemental Ionization System (EIS), which employs a particular blend of elemental ion chargers and non-contaminating additives to decontaminate wastewater. Scalada said EIS offers a solution that is “eco-friendly, cost-effective and more efficient that any other water treatment system of its kind.”