Custom smelters are offering a service to the mining companies by converting copper concentrates with a copper content of typically 20-25% to copper cathodes.
TCs are charged in US$ per tonne of concentrate smelted. RCs are charged for refining copper anodes to produce copper cathodes by electrolysis. This charge is expressed in ct/lb and refers to the amount of copper in the concentrate.
TCs and RCs are very volatile and can change from year to year as well as within a year. Díaz-Borrego provides a table of historic TC/RCs for the period of 2004 - 2017:
|Year||TC (US$/ton)||RC (ct/lb)||Year||TC (US$/ton)||RC (ct/lb)|
TC/RCs provide part of the revenue of a smelter. E.g. the table below gives an indicative calculation for revenue per tonne of copper for various TC/RC levels and levels of concentration:
|Level of concentration|
Smelters can have other sources of revenue besides TC/RCs:
- Sulfuric acid, although normally, the costs for sulfur fixation in sulfuric acid are higher than the credit for sulfuric acid.
- Free metal, such as additional copper, gold and silver extracted from the concentrate above the amounts estimated.
- Penalties related to the amount of deleterious elements in the concentrate (mercury, arsenic, bismuth, lead tellurium, selenium, antimony, fluoride) above a certain accepted level.
- Innovative revenue streams include the valorisation of residual heat from operations  or the use of iron-silicate slags in civil engineering and construction projects.
Langner provides an example of a revenue distribution for a particular smelter. This breakdown is based on assumptions related to concentrate composition, TC/RC, commodity prices and process efficiencies. Such breakdown will vary significantly per smelter as well as with time. In particular, the proportion of TC/RCs in total revenue may be much higher in some cases, as TC/RCs may vary from year to year as well as within a year.
Other breakdowns of smelter revenues are given by Boliden in references, showing TC/RC revenue representing 33 - 54% ot total revenue.
Considering this volatility of revenues and rising energy and climate costs, running a smelter/refiner operation requires skill, prudence and a long-term vision.
- Díaz-Borrego, Francisco J., María del Mar Miras-Rodríguez, and Bernabé Escobar-Pérez. 2019. “Looking for Accurate Forecasting of Copper TC/RC Benchmark Levels.” Complexity 2019 (April). https://doi.org/10.1155/2019/8523748. Accessed July 27, 2021
- Langner, Bernd E. 2011. Understanding Copper: Technologies, Markets, Business. Page 168. Accessed July 27, 2021.
- Industrial Heat - A Climate Alliance of Aurubis and enercity. Accessed July 27, 2021.
- See slide 22 of Boliden 2007-2008 or page 46 of Boliden 2021. Accessed March 31, 2022.
Last update: July 1, 2022