CAN CRITICAL METAL SUPPLY PROBLEMS BE SOLVED USING EXISTING BUT HIDDEN MATERIALS FLOWS? TELLURIUM AND THE USA-CANADIAN MINING VALUE CHAIN

The transition towards zero-CO₂ energy generation, storage and transport requires a range of metals generally considered critical in terms of security of supply, commonly represent low volume byproducts of other metals, and are increasingly challenging to produce. Using tellurium as an example, we demonstrate that the issue is often not insufficient resources or active mining. The majority (>90% or ~400 tonnes) of current tellurium production is sourced as a by-product of copper mining, with even this metal supply chain having significantly more tellurium lost to waste than recovered. This reliance on copper production also increases uncertainty around whether increased demand for tellurium can be met by current mining and refining practices. One solution to any looming tellurium crunch is by-product tellurium derived from active gold mines. Accessory, precious metal-bearing tellurides are common in many gold deposits although tellurium concentrations are not routinely determined, making tellurium deportment difficult to quantify. This study presents a proxy analysis of 518 mineral deposits that are known to contain tellurium, of which 65 are active gold mines, yielding an unrealized global by-product tellurium potential of some 167,000 tonnes or about 300 years’ worth of current Te production. These include active base and precious metal mining supply chains in the USA and Canada that contain significant, unrealized byproduct tellurium supply potential. Some 18 USA and Canadian gold mines in our database could produce ~90 t/yr tellurium, with a further six copper-zinc and nickel-copper mines in Canada having the potential to produce ~130 t/yr and ~ 40 t/yr tellurium, respectively. The above byproduct tellurium potential contrasts with current annual tellurium production of 90 t/yr from copper refining in the USA and Canada and is a result of the current lack of policy and economic drivers to incentivize the recovery of byproduct critical metals. This study demonstrates that tellurium exemplifies the by-product nature of many of the elements considered critical by governments worldwide and, for some active gold and base metal mines, could provide future economic value, resource sustainability and the necessary raw materials for the technologies needed to achieve carbon neutrality.