There are two things that could have major impacts on improving the viability of mining projects:
1. Planning, developing and operating projects with the end-use, full closure design in mind (and this means planning and building it to progressively enable closure shortly following the end of operations of a mine), and
2. Flipping evaluation of a potential development on its head - evaluate the worth of the entire property - with value placed on every component of the system - including the overburden and "waste" materials being excavated and moved in order to reach that desired, valued ore. This is monetizing the waste streams that every operation generates - at the front-end planning and assessment phase.
The focus of this article is on the latter topic, as it is the most 'out-of-the-box' when it comes to this sector. Hopefully the questions herein will generate a lot more dialogue, perhaps they will entice you into asking more questions, and perhaps you might even take immediate actions to shift the forward direction of your operations.
So, back to placing value on waste materials. You might ask, isn't this already done? To be sure, the cost of blasting, moving, stockpiling and otherwise capturing, treating and managing waste materials are accounted for, but value placed on them, as in commodities for sale? Not typically.
Common practices include use of some aggregate waste streams in construction of on-site facilities, for roads on site, and of course - always - for capping and closure of a site when it is required, if it is clean enough. Again, the costs of moving the materials seem to be accounted for, but not the value of the materials themselves. And why not? Because it's already there, and is essentially "free". There is only the need to test it (captured within operational expenses), to ensure it is clean, compatible rock, useable for its intended purposes, to account for in economic analyses - a bonus, really, for using it (especially if it can all be consumed) reduces the cost of managing and reclaiming it later on. Better yet, even more savings could be realized if the material's use is planned from the start - i.e., lab results of exploration and pit development samples, flagged as clean, could eliminate a lot of stockpile sampling, and the materials could be placed in the most appropriate location for its use directly after excavation (reducing rehandle costs!)
What if a company placed more value on such materials? And if so, what value would be associated with each one?
In the case of aggregate, there are easy ways to figure this out:
- Investigate what others might have paid for it in the region, and add that to the expense of shipping it to the site - what would it cost if they were purchasing it from local suppliers, such as in the case of a less remote setting?
- Determine the costs associated with the exploration, testing, design, permitting, development and reclamation of a borrow pit for these same materials, adding that to the expenses of crushing / segregation of the materials to reach the appropriate spec's - As a standalone development, what now would be the aggregate's worth?
- Determine the potential uses for it in the local region - could any of those materials be re-purposed off site - in remote communities for construction of infrastructure, in road developments for access to local communities or other properties, near and far? How much value does this material have - if not for the mine owners, for others who might need it? Is there a potential market for these materials? You have the aggregate on site. Money has already been spent on its extraction. What revenue might be made if value was added to this resource by crushing and segregating to spec's others might need, on demand? How much might a company gain by placing value on these commodities?
Similarly, what about other elements that might be associated with a desired orebody? Why is an orebody developed and processed with only the major constituents targeted? How much value is left in the mineralized waste rock, in the tailings, after money has been spent to segregate and / or precipitate these other 'contaminants' into a solid form, and more money is spent on the transportation of these materials to waste facilities? And then more money yet spent on managing these waste materials - often in perpetuity, to help mitigate risks of environmental damages caused by these leftover metals leaching into the downstream?
Instead, why not look at the full cost, the life cycle cost, of all these things together, and compare them against the cost of adding one or two additional processing steps - to extract these other elements directly through processing, put them in a saleable form, and remove them from the list of potential problem causers of the future? What is the 'cost', then, of extracting these additional elements? Or alternatively, what are the savings gained from extracting them? After all, the benefits are not only gaining the value associated with those saleable products, but also the reduced financial liability associated with managing them as stored wastes, contaminants, and potentially leachate constituents that must be kept out of down-gradient surface and subsurface water bodies.
And what of the components that really don't have sufficient marketable value? Easy - try to minimize how much of that you are generating! Optimize segregation of the valuable pieces of that puzzle, store them in a safe place until closure, and incorporate them into the mined-out areas as fill to restore the property to align with natural landforms.
It is really win-win-win...extra value recovered, risks minimized or eliminated altogether, and long term liabilities reduced. The opportunity can be realized on many types of 'waste' that mines and processors manage. So why aren't we doing more of it?
The technologies are there - processing options have been developed for all sorts of elements. It's just that mining companies tend to focus on only one or two target ores for each property they assess. It's their business strategy - to maximize the value of their core lines of business - they haven't typically assessed the worth of other things on the site, especially if those materials are typically considered a cost to manage and would not otherwise be considered to have worth - like waste rock or waste water.
But a suggestion to consider - because it really is all worth something, to someone. If you or your company doesn't want to manage that extra business opportunity, consider partnering with one that would!
Here are a few examples - there are definitely more out there, but these were selected because they span the various sources of waste - water treatment processes, mineral processing, and plant air emissions. Most of these projects have come to fruition only after extraction of the desired orebody have commenced (or even after completion), and often also reflectively, after the needs of local or nearby stakeholders have been taken into account. But they don't need to be.
1. The first example is a first of its kind plant in the mining industry - Anglo American's eMalahleni plant in Mpumalanga province, South Africa. The plant purifies waste water from five mines, turning it into drinking water for local people. The gypsum waste produced from the treatment process is made into bricks to build homes that will enable workers moving away from mine villages to buy affordable homes. It recovers 99.5% of its water and provides 80,000 people with drinking water, meeting 20% of their daily needs and those of the five mines. That's a lot of value that mining companies have typically viewed as two things: a cost to treat waste water just to discharge it safely to the environment, and a cost of storing and managing a resultant waste stream from said treatment.
2. The second example is a product that has been developed with copper mine tailings and steel waste products. Ferrock™ is essentially "construction materials that are environmentally superior, sustainable, and mechanically stronger than conventional concrete, and it not only makes a use of a waste stream, it also absorbs CO2 permanently, making it carbon negative. With a couple minor additives, the iron in the waste reacts with carbon dioxide gas and forms a mineral that hardens a wet paste around the aggregate, which, rather than stone, can be another waste material like crushed glass." Again, a valued product once viewed as a waste stream (or several) to be managed.
3. Another technology, still in development, through Sustainable Development Technology Canada - an organization whose aim is to "bring economically viable, clean technologies to market." It is a process to re-mill 'red mud' tailings, which were generated from producing alumina from bauxite. According to the developer Orbite, "red mud is the caustic by-product from the Bayer process, which has been around since the 1880s...and has remained essentially unchanged since then. Globally, approximately 3 billion tonnes of red mud is stored, and while no viable alternatives have been developed to utilize this material, annually, some 120 million additional tonnes are being produced...Red mud can contain up to 25% alumina, with other valuable constituents, such as scandium, gallium, titanium, hematite and rare earths present too. To date, this value is discarded, but Orbite has developed a process that has achieved high recovery rates for alumina, Rare Earth Elements (REEs) and Rare Metals (RMs) from these wastes, as well as selective recovery of the remaining metals in the leachate, such as magnesium, gallium, scandium, and rare earths, recovering all the value from the feedstock." Orbite also claims they can also process fly ash and other mine tailings for recovery of valuable constituents, leaving very few residual materials behind.
4. This final technology was highlighted by the Globe and Mail and is applicable to the cement-making industry. CarbonCure Technologies is a Halifax-based company that has developed a technology to recycle its carbon dioxide gas back into solid concrete by reversing the cement process. "Cement, an active component of concrete, starts its life as a fine powder that is produced by heating limestone and clay together. When added to a mixture of sand, gravel and water, cement acts as the glue-like substance that gives concrete its binding properties." Through research, it was discovered that the carbon dioxide emissions could be captured and reintroduced into the cement through a chemical reaction, where it forms a bond with the cement, essentially reforming limestone. "The technology itself is a suitcase-sized piece of machinery with a control system that gets retrofitted onto the existing production machinery at concrete plants. CarbonCure’s device then tells the equipment how and when to introduce the carbon dioxide into the concrete."
We already know that a lot of work has been going into assessing the uses of water and energy in more holistic, systematic ways, to reduce consumption, to reduce costs, and to reduce impacts on the environment. Aside from the environmental benefits of optimized consumption, this is primarily because both water and energy are associated with holding value, and by reducing consumption of these, companies can save money. Why can't the same logical thinking go into the other resources being managed on a mine site - place value on those streams that would otherwise be considered waste. They really do hold value, even if only to be used as reclamation materials.
In closing, if more materials were assessed in this way, it's likely that development, processing and handling or storage methods would be adapted to ensure the quality of those materials were maintained and managed in a way to ensure their value was also maximized. This refers back to the very first bullet - planning and operating with the end-use in mind. It comes full circle.
What wastes does your property manage, that may hold value for another? Why not highlight its value to those potential users?