The Future of Tailings Management

What are Tailings?

The mechanical and chemical processes used to extract the ore from mined rock leaves behind a mixture of finely ground rock and water. This mixture is known as tailings. Tailings are stored in various ways but are generally stored on or near to the site. The location and method of tailing storage is dependent on their chemical and physical nature, mine site geography, climate and environmental conditions, local regulatory guidelines, and the location of mineral processing and operations. Although mine tailings are rejected products with no immediate economic benefit for the mining operators, these mine wastes could be sources of valuable secondary materials. Reprocessing of extractive wastes is encouraged in the framework of the circular economy (ICMM, 2016, p. 6). 

Tailings Management and Sustainable Mining

Recently, there has been an increased focus in the mining industry to further improve responsible standard operating procedures and invest more into sustainable mining practices. Guidelines such as the Global Industry Standard for Tailings Management, and the Mining Association of Canada’s (MAC) Towards Sustainable Mining initiative have been significant driving forces behind the industries shift to more sustainable and responsible mining practices. The United Nations (UN) also defined guidelines to advance sustainable development in the 2030 Agenda, which highlights that the industry must enhance its pursuit of sustainable mining.

What Does This Mean?

For mining companies, it means that there will need to be increased focus on tailings management and finding innovative sustainable mining practices. Beyond constructing geotechnically stable landforms or managing water quality, finding innovative, revenue–generating, and sustainable ways of managing tailings is key to the future of the industry. Tailings reprocessing could be a viable way of managing tailings and generating revenue from legacy tailings storage facilities.

Tailings Reprocessing

When tailings are reprocessed, through various developing industrial technologies, up to 90% of water can be removed and the tailings can be stored in a dry stack (Leonida, 2019, par. 18). The dry-stack tailings storage method refers to unsaturated tailings being used to construct the landform, which is typically more viable from a geotechnical stability perspective, more feasible for re-vegetation, and makes it easier to create a landform that matches the surrounding environment and ecosystem (Davies, 2011, p. 3). Additionally, re-processing may reduce the metal leaching and acid rock drainage potential of the tailings.  Doing so has the potential to further reduce environmental and economic liabilities. Further, tailings could also be pumped back into the tailing’s storage facility once reprocessed.

What are the Benefits of Tailings Reprocessing? 

One benefit of tailings reprocessing is access to critical raw materials (CRM’s). CRMs are minerals and metals that can be considered critical to sustaining a country’s successful economy (Government of Canada, 2021, par. 3). Examples of CRMs that are considered critical to Canada’s economy include minerals such as copper, nickel, uranium and zinc. Other less common minerals included in Canada’s list of CRMs include cesium, germanium, and manganese (Government of Canada, 2021, par 3). Although the Canadian government has defined a list of CRMs important to their specific economy, there are many other minerals and metals that can be classified as CRMs in other countries/regions.

More traditional products can also be recovered through tailings reprocessing. For example, Heritage Minerals’ Mount Morgan project is planning to reprocess tailings to acquire gold. Another example is Barrick’s Golden Sunlight project which is reprocessing tailings to recover sulfur. Minerals and metals vital to economies can be abundant in mine tailings, and there are many mine companies that are looking to find ways to extract them via tailings reprocessing.

Historically, limited research had been conducted to identify the various types of CRMs within mine tailings, whether there was enough to make it worthwhile, or if it was even marketable. Additionally, the technology needed to characterize the CRMs within a tailings storage facility (TSF) and extract them can be costly. However, with the amount of tailings storage facilities across the world on both legacy mine sites and active mine sites, it’s becoming increasingly plausible that access to CRMs in mine tailings could be substantial.

The demand for CRM’s is also increasing substantially. CRM’s that have been found in tailings are useful in the construction of many materials across technological and industrial industries. For example, CRMs identified by the Government of Canada such as nickel and copper are critical in the development of smartphones, laptops, and tablets. Items people use daily in their work and personal lives. CRMs such as lithium, also identified as critical by the Government of Canada, is widely used in the development of batteries. Other CRMs like sulfur, being extracted from tailings by companies like Barrick as previously mentioned, are widely used in cleaning products and fertilizers.  

Further, CRMs are a vital component in the construction of clean energy technologies such as solar panels and wind turbines (European Commission, 2020, p. 23). Solar panels that use solar cells are often constructed using minerals such as indium, lithium, and gallium, minerals that were identified as critical by the European Commission in 2020 (European Commission, 2020, p. 3). These technologies are becoming increasingly relevant to economies and businesses all over the world as industries continue to experience pressure to transition toward clean and sustainable resource collection, especially in the energy sector.

In addition to accessing CRM’s, reprocessing of tailing could give mine operators access to water at a fraction of the current cost. Water recovered from tailings reprocessing can be used throughout the mine site, or replace water lost from evaporation. If mining companies are going to be spending money on water to use at a mine site or to replace water loss, and spending money on mining for CRM’s elsewhere, it may be a feasible option to obtain both via tailings reprocessing.  

Not only could there be an economic benefit for mining companies, but there are also environmental benefits to tailings reprocessing. Reprocessing tailings could help mining companies achieve their sustainability goals in the future by producing benign tailings residue and reducing the environmental risks of dam structures. These benign tailings also significantly lower the need for water management on-site, reducing residual risk and long-term water management costs. This can be a major economic benefit over-time for mine operators.

Reprocessing or repurposing mine tailings have been studied by researchers such as Natalia Araya, Yendery Ramirez, Andrzej Kraslawski, and Luis Cisternas, but for the broader implementation of applied technologies for this approach, a comprehensive commitment must be established, supported by multiple stakeholders from industry, academia, and policy organizations. 

Research, Development, and Tailings Reprocessing at Okane

As mine closure experts, we are helping mining companies shift their perspective on the potential benefits for reprocessing tailings. We evaluate the potential of tailings reprocessing from the perspective of mine closure and environmental risk management. When considering tailings reprocessing as a potential closure option, we investigate site-specific tailings’ characteristics, current storage facilities, and future landform designs for the residual post-processing tailings. We also look at opportunities from the perspective of future retuning land use, where tailings reprocessing could benefit to local economies and communities. If tailings reprocessing is a viable closure option for the site, we can identify and engineer management options for the remaining tailings through expert landform design and cover systems.  

At Okane, we’re always encouraging our team to advance the industry through innovative research and development projects. Tailing’s reprocessing as a mine closure solution is an area we are actively exploring to help our clients lead the way in innovative tailings management solutions.

References

Araya, N. Cisternas, L. Kraslawski, A. Ramirez, Y. (2021). Feasibility of Re-Processing Mine Tailings to Obtain Critical Raw Materials Using Real Options Analysis. Journal of Environmental Management 234. https://www.sciencedirect.com/science/article/pii/S0301479721001225 

Davies, M. (2011). Filtered Dry Stacked Tailings. Proceedings Tailings and Mine Waste 2011. http://dx.doi.org/10.14288/1.0107683 

European Commission. (2020). Critical Raw Materials Resilience: Charting a Path Toward Greater Security and Sustainability. https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:52020DC0474&from=EN 

ICMM. (2016). Mining and Metals and the Circular Economy. International Council on Mining and Metals. https://www.icmm.com/website/publications/pdfs/mining-metals/2016/research_circular-economy-2016.pdf 

Lovegrove, S. (2023). Tailings at a Northern Territories gold mine [Digital image]. Ashima Sharma. UpToDate. Retrieved March, 5, 2024, from https://www.mining-technology.com/features/what-sponges-and-microbes-make-of-mine-waste/

Leonida, C. (2019). Mine Tailings: Reprocess, Recover, and Recycle. The Intelligent Miner. https://theintelligentminer.com/2019/09/13/mine-tailings-reprocess-recover-recycle/