Mintek is leveraging two decades of accumulated research and learning to develop a water-treatment process for mining-impacted water that is environmentally responsible, technically robust and commercially viable.

Mining and mineral processing depend on water and, increasingly, the industry must find ways to use less and recover more water, and to ensure that water leaving mining operations does not become an environmental burden.

“Our work on mining-impacted water brings together Mintek’s capabilities in mineral processing, hydrometallurgy, environmental technologies and process optimisation to develop practical solutions that improve water efficiency, increase reuse, reduce environmental risks and strengthen the industry’s resilience to water scarcity,” says Mintek CEO Dr Molefi Motuku.

One of the technologies at the centre of Mintek’s ongoing work is Savmin, which was developed in 1998 to treat acid mine drainage (AMD).

Savmin, a portmanteau of Savannah Mine and Mintek, is an ettringite-based chemical treatment technology designed to generate portable water by precipitating dissolved sulphate contaminants in mining-impacted water, such as calcium sulphate, into stable solid products which include commercial- grade gypsum.

In 2008, Mintek’s first pilot plant, developed in partnership with Atomaer, used commercial aluminium oxide to precipitate calcium sulphate into ettringite. However, this did not yield the desired results, as it was unreactive when contacted with calcium sulphate, leading to the discontinuation of the project.

By 2010, new intellectual property had been developed to address the limitations of the 2008 pilot plant operation, with a key development around the use of amorphous aluminium oxide to precipitate calcium sulphate, followed by the subsequent recovery of the resulting ettringite for reuse.

In 2016, Mintek partnered with Viola Water Technologies to further test the technology through a pilot plant, generating valuable insights for subsequent research.

Mintek later built its own reactors and conducted further trials, which confirmed that the Savmin process could work with further refinement.

Now, Mintek is taking another step in its journey with the technology: the in-house construction of a mobile pilot plant designed to fit inside a six-metre standard container, capable of treating 5 000 litres of mining-impacted water daily.

The new pilot aims to validate the process refinement and operate the plant under real-world conditions, with a focus on improving both technical performance and technology visibility.

“We are investing time and resources in refining Savmin technology into a zero-waste process by turning calcium-sulphate-contaminated wastewater such as AMD into portable water and commercial-grade gypsum, while improving the commercial viability of the technology by reducing the cost associated with the quality of recovered amorphous aluminium oxide,” says Mintek metallurgist Tshamano Netshikhudini.

Mintek is using more than two decades of accumulated research and learning, rather than just revisiting an old technology.

“The continued development of technologies such as Savmin demonstrates why sustained research matters. What began more than two decades ago has evolved through setbacks, new knowledge and technological advances,” Motuku says.

“We are applying that accumulated knowledge to improve the process and move it closer to environmental and commercial viability. This is the value of long-term research, turning challenges into opportunities for innovation.”

Mintek points out that research does not always follow a straight line, with setbacks generating knowledge, partnerships creating new opportunities and technologies evolving as new scientific understanding emerges.

Mintek’s Integrated Solutions for Mine Impacted Water research programme focuses on innovative and sustainable solutions for the management and treatment of mine effluent and mine impacted water.

The programme takes a holistic approach, addressing water treatment, reuse and efficiency across the minerals processing value chain.