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Founder & Principal @ McClintock Group| Co-Founder EOC | Enhancing Mineral Projects, Advocating for Shareholders
♻️ Tailings Reprocessing: The Holy Grail or a Fool’s Errand? Mines naturally handle a complex set of factors like resource allocation, capital efficiency, opportunity costs, and depletion. What works for one mine at one time may be completely different for another. This makes decisions like cut-off grades incredibly tricky to get right. Recovering every possible mineral might seem ideal, but it’s often not practical—at least not today. As cut-off grades drop, tailings themselves start to look more like assets. The idea of tailings reprocessing becomes increasingly compelling, not just for the economics but for the environmental opportunities it presents. Vale, for example, expects 10% (7 million tonnes) of its iron ore production to come from tailings by 2030. As reserves deplete, there’s a clear case for revisiting tailings, improving handling, and rethinking closure plans. But, as with most things in mining, it’s never that simple. 1) Random Distribution: "Nuggety" Nature of Tailings Grades in tailings depend heavily on when and where the material was discharged. They’re shaped by the ore being processed, recovery rates, and even whether it was a bad operating month. This variability creates a distribution that can shift dramatically and often feels, for lack of a better word, nuggety. Tailings reprocessing is far from predictable, and that inconsistency can complicate both planning and operations. 2) The Bias: Preferential Liberation and Extraction Tailings grades may look great on paper, especially when compared to today’s ore. But they’re not directly comparable. When ore is processed, the easiest minerals are recovered first. What’s left behind requires significantly more energy and effort to extract. A tailings grade of 1 g/t Au might seem impressive, but metallurgical recoveries, and feed variability, I would argue should have a discount to account for the difficulty of recovering the remnant mineralization. ▪️Lessons from the Carlin Trend A century ago, mining sub 1 g/t Au material would have been unimaginable. Today, projects targeting 1 g/t Au open pitiable are common. The same shift could happen with tailings, but success depends on understanding the metallurgy, the inherent variability, and the cost of recovery. So, are tailings reprocessing the holy grail? Maybe. It depends on timing, economics, and a willingness, technology of the day. But what is for certian is they repersent a chance to reduce existing footprints and bring past standards up to current ones. It is a beautiful thing - economics and how changing markets open up pathways. #Mining #Exploration #Metallurgy #MiningInnovation #ResourceManagement #FutureOfMining #TechInMining #Gold #Zinc #Copper #MiningIndustry
My view on it is - you need to learn the old plant also it's location. In Eastern Europe the tailings grades get lower as you go deeper. Maybe in the western world the the plants improve over time so at depth it's higher grade waste? As the Soviets focused on selling the highest and best grade concentrates as investment reduced - the highest grade tailing material is on the surface. Plant history - did equipment change in the plant? Did they bring in new/change the plant? Did they look at different gangue minerals? Also mineralogical liberation. It's a tailings material. Why is it in the tailings in the first place? Incompetence? Bad plant design? Or is it locked up, wrapped so tight that remilling it will just slime it to an unrecoverable size fraction. The other thing you've got to remember is that if you are looking at floating the material it may still be lagged reagents. Which may mean it's not going to behave like fresh ore! To me you need to geomet the tailings with knowledge of the history of the plant. Did they move the discharge pipe?
🙌 Excellent analysis. I rescue the concept ‘as cut-off grades drop, tailings themselves start to look more like assets’ because ultimately it is an opportunity to extract already mined minerals more efficiently or to extract those that never sought to be extracted from the tailings that lie in many sites. Regarding the variability of tailings composition, this could be managed in current operations with measurements (large volumes of data), analysis of concentration distributions, and engineering to arrange tailings disposal according to chemical composition. We would then have a ‘shelf of labeled resources’ for when market conditions, technology, or cut-off grades change. As in the management of any waste, initial disposal and segregation are essential to obtaining value from the materials by reprocessing at lower costs.
Your analogy to the Carlin Trend’s evolution is apt, illustrating how industry standards can shift dramatically over time. The potential for tailings reprocessing to reduce existing footprints while upgrading past practices to current standards is indeed promising. Ultimately, tailings reprocessing isn’t a one-size-fits-all solution, but rather a valuable tool in the mining industry’s toolkit. Its success depends on careful analysis, technological innovation, and alignment with broader sustainability goals. As you eloquently put it, it’s “a beautiful thing - economics and how changing markets open up pathways.”
Michael McClintock, P.Eng. Your conclusion resonates deeply. I’d like to contribute by highlighting challenges in iron and silicon tailing reprocessing, focusing on storage and cost. Storage Techniques: Storing tailings, often in slurry or fine particles, poses risks like groundwater contamination. In silicon mining, dust from tailings is a major concern. Dry stacking or using tailings as backfill materials are options but often insufficient for large-scale reprocessing. Reprocessing Cost: Costs depend on technology and mineral content. For example, ultrafine grinding and advanced flotation are viable for iron ore but remain expensive. Silicon tailing reprocessing through hydrometallurgical methods is promising but economically challenging due to low recoverable material content. Some tailings are used in construction, reducing waste but yielding limited profit. For tailing recovery to succeed, profitability must outweigh costs, or it will remain an environmental holy grail rather than an economic solution.
Mr. McClintock; very well presented, and completely agreeing with your comment. However, I would like to add that there is a significant decrease in cost by processing tailings due to the lack or reduction of grinding unit operations (almost 50% of the cost of mineral processing a mineral). As you mention, treating tailings may be more difficult, but blending techniques and new processes are now available to treat refractory ores that have improved significantly.
The issue is what to do with the new Tailings? Where and how to dispose?
A recent project a friend of mine oversaw was reprocessing century old coal tailings. It was possible to get enough useful material from the discards to make it profitable to recover them. As a bonus, the area in question had a lot of contaminants removed.
Tailings reprocessing presents a unique paradox—an opportunity to unlock value while reducing footprints, yet fraught with variability and metallurgical challenges. As markets evolve and technology advances, the key question remains: How do we balance the economic promise with the operational unpredictability to make this a viable pathway for investors and stakeholders alike?
Although I am obviously not an expert, it is clear that reprocessing #tailings brings value and makes sense from financial as well as circularity perspectives. Karen Chovan
Mechanical Maintenance
5dRecently worked for New Century in Australia. Largest tailings reprocessing operation in the country. Hydro mining old tailings, reverse engineered the processing plant to bypass the ball and sag mills, straight to floatation. Company has now been procured by sibanye stillwater. The operation has recovered over 750,000 tonnes of zinc concentrate at a very low cost per tonne recovery rate. Very interesting operation to be a part of, many challenges in processing, especially through the dewatering filtration due to particle sizing and bonded reagents.