OZ Minerals engaged Exact Contracting to construct Stage 1 of its cross-valley tailings storage facility (TSF) at the Carrapateena copper/gold mine northeast of Port Augusta, South Australia. The TSF comprised three primary embankment structures – decant dam embankment, TSF embankment and causeway – totalling approximately 500,000 m³ of imported general fill, select fill and clay. (Photo: Exact Contracting)

OZ Minerals, Boliden and Rio Tinto recently announced that they will collaborate to unlock new, innovative technologies for managing mine tailings.

Under the umbrella of the Think & Act Differently (TAD) incubator initiative originally launched by OZ Minerals, the three companies said they’ll fund and support innovators who are working to reimagine mining and processing to eliminate, minimize, reuse or find value in mine tailings. They will also collaborate on other selected innovations to pursue improved productivity while delivering benefits such as lower emissions and reduced waste.

Regarding the three-company collaboration, Michelle Ash, OZ Minerals’ technology executive, said, “We can accelerate technology much faster by working together and this is an example of how the industry can collaborate to support technology development.  We hope this way of working and supporting innovators provides a model that can be replicated because accelerated technology development is likely to have a positive impact on our industry and society.”

Joanna Lindahl, Boliden Mines’ sustainability director, commented, “By collaboration on generic challenges for the mining industry in a pre-competitive setting we will be able to make progress faster and more resource efficient. For the inventors and startup companies in the TAD incubator, it is also an excellent opportunity to get insights and business understanding from several different mining companies. We are very much looking forward for this collaboration and hope to find new opportunities to strengthen the industry in the future.”

The companies said the collaboration will support innovators by providing materials, funding, technical guidance and the potential for field trials at mine operations. Innovators will retain ownership of their intellectual property rights, with a license to use those rights granted to the companies that support them.

As mentioned in our recent coverage (see “Strategies of Containment”, pp. 30-35, E&MJ, October 2022), tailings management is a rapidly intensifying cost center and social/legal liability for the mining industry – but also an avenue towards new opportunities in metal recovery offered by innovative advances in tailings and waste processing. Research organizations and private enterprise are aggressively promoting concepts aimed at capturing government and private funding to develop and eventually commercialize new techniques for minimizing tailings volume and/or recovering energy minerals from tailings and waste (see story below).

The overall cost of an unexpected tailings storage problem is almost always significant, often encompassing both financial impact and social reverberations. A number of major mining companies have experienced major-expense events associated with tailings management,
and even companies that have been mostly incident-free would like to find ways to avoid future problems. In April 2022, for example, Boliden announced that it planned to spend $530 million over the next two years for improvements to a tailings dam at its Aitik mine in northern Sweden. The discovery of poorer-than-anticipated soil conditions prompted the company to suspend dam heightening and tailings deposition there and investigate new dam construction techniques to accommodate future tailings storage, as well as to take steps to bolster its methods for current dam construction.

On a global basis, studies have shown that copper production is the largest contributor to the steadily rising volume of tailings – stemming from the industry’s need to process higher amounts of lower-grade ore – accounting for an estimated 46% of all tailings produced yearly. In October, BHP and Rio Tinto said they had formed a partnership agreement to accelerate the development of technology that could significantly increase water recovery from mine tailings, and in turn, reduce potential safety risks and environmental footprints associated with tailings storage facilities.

The first project will involve testing the application of an innovative large-volume filter unit at a BHP copper mine in Chile, which would remove up to 80% of the water in the tailings stream before it is deposited in a storage facility.

Rio Tinto will bring its experience from implementing smaller-scale tailings filters for bauxite residues at alumina refineries since 2005. Both organizations will work in collaboration with leading technology and equipment providers.

The pilot construction is due to begin in early 2023 and operations are scheduled to commence in early 2024. The pilot will test the potential of a large-scale tailings filter unit for scalability and cost-effectiveness across global mining operations.

OZ Minerals reported in September that four teams experimenting with extracting value from waste had joined its Think & Act Differently’s Waste to Value Challenge, which invited innovators to propose ways to minimize, eliminate and find value in waste. The company said overall it received 37 submissions for this challenge. The final cohort includes:

• Beyond Digging – a collaboration between national and international research organizations and academia.

• University of Portsmouth – (Customized bio-mining).

• Clean & Recover – (Acid mine drainage metals recovery).

• Jord – (Coarse and fine particle recovery, through the NovaCell patented flotation technology).

In a related development, on December 22 BHP announced that OZ Minerals had agreed to an arranged transaction scheme with BHP Lonsdale Investments, a wholly owned subsidiary of BHP, under which BHP will acquire 100% of the shares in OZ Minerals.