Mintek is leveraging two decades of accumulated research and learning to develop a water treatment process for mine 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, recover more and ensure that water leaving mining operations does not become an environmental burden.

“Our work on mine 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,” said Mintek CEO Dr Molefi Motuku.

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

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

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

By 2010, new intellectual property was developed aiming at addressing the limitations of the 2008 pilot plant operation, with a key development around the use of amorphous aluminium oxide to precipitate calcium sulphate and subsequent recovery from the resultant 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 l/d of mine impacted water.

The new pilot aims to validate the process refinement and operate the plant under actual 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,” said Mintek metallurgist Tshamano Netshikhudini.

Mintek is not simply revisiting an old technology, but rather using more than two decades of accumulated research and learning.

“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 continued.

“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 pointed 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.

Key research areas include technologies to treat mine-impacted water for reuse, water efficient mineral processing flowsheets, process modelling and simulation, AMD prevention and environmental monitoring.