Carbon negative mines: mineral carbonation of mine waste

The Challenge

Gold and nickel mining operations in WA generate 80 to 100 million tonnes of tailings annually, which increases the risk of acid and metalliferous drainage (AMD), contributing to environmental pollution and high carbon emissions. Stakeholders, including mining companies, communities, and governments, are increasingly concerned about the environmental and social impacts of AMD and CO₂ emissions. The challenge lies in managing this waste sustainably while reducing the carbon footprint, which is significant, as traditional methods for waste treatment (such as the addition of limestone – CaCO₃ for AMD treatment) can themselves be carbon-intensive. This project will devise a method to precipitate CaCO₃ or MgCO₃ in engineered wetlands i.e., ex-situ via mineral carbonation of tailings to tackle the challenge of adding an external CaCO₃ or limestone for AMD treatment of these tailings.

Proposed Solution

Current mineral carbonation research primarily focuses on ultramafic wastes from nickel, platinum, and diamond mines, which are limited in WA. This project proposes an innovative solution for carbon sequestration by converting weathered tailings into inert carbonate minerals using an alkaline lixiviant derived from industrial alkaline by-products. It aims to quantify the carbon sequestration potential of gold and nickel tailings in WA, while also developing and characterising an alkaline brine generated through microbial photosynthesis to enhance mineral carbonation in gold and nickel mine waste.

Proposed Benefits to WA

The project’s outcomes will yield significant environmental and economic benefits for Western Australia, directly supporting the state’s Climate Policy and Sustainable Development Goals. By transforming mine waste into a strategic asset, the success of this project will:

• Establish a Western Australian Carbon Sink: Generate vital knowledge on the efficacy of mineral carbonation using widely available gold, nickel, and iron ore tailings. This potentially unlocks a multimegaton carbon sink, diversifying the state’s sequestration strategies beyond traditional methods.
• Decarbonize the Mining Lifecycle: Provide the groundwork for a novel, cost-effective, and scalable protocol for carbon sequestration. This technology will directly reduce the Scope 1 and 2 emissions profile of mining activities, ensuring the sector remains competitive in a low-carbon global economy.
• Champion Circular Economy Principles: Demonstrate how mine tailings, traditionally a long-term liability, can be repurposed for environmental remediation, creating a blueprint for “Zero-Waste” mining operations in WA.

Funding DOI

DOI: 10.71342/467171811964