Mount Toromocho, meaning in Spanish "a bull with no horns", is a mountain in the Junín Region, Peru that sits next to the long established mining camp of Morococha and hosts a large polymetallic metal deposit. It is now owned by the Aluminum Corporation of China (Chinalco), a parent company of Chinalco Mining Corporation International (CMC). Minera Chinalco Perú S.A., a subsidiary of CMC which operates the Toromocho mine, is boosting the mine's productivity with a new production line.
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History
The mineralisation on Toromocho has been known and mined on a small scale for many years and was drilled by both the Cerro de Pasco Corporation and its successor (after nationalization) Centromin between 1966 and 1976 but it was evidently not considered worth exploiting, possibly due to lack of finance in the case of Centromin and the spectre of nationalization in the case of Cerro, or because it did not look economically viable at the prevailing metal prices.
Peru Copper Inc was formed in February 2004 and took over the Toromocho option that had been successfully bid for from Centromin by its predecessor company. The five year option required certain expenditures which Peru Copper completed satisfactorily and the option was exercised on 5 May 2008. There is no indication of any further payment for the exercise of the option.
In the meantime on 11 July 2007 Chinalco purchased Vancouver listed Peru Copper Inc for C$840 million and it became a wholly owned subsidiary of Chinalco. The new owner now plans to establish an open pit copper mine at a cost of US$2.16 billion to produce 210,000 tonnes of copper annually.
The mine
Chinalco estimate that it will cost US$2.16b to bring the Toromocho mine to production in 2012 and that annual production will be 210,000 tonnes copper.
Operating costs are likely to be relatively high per pound of copper despite a low stripping ratio (the amount of waste that has to be moved to access the ore), again due to the low grade coupled with the adverse working conditions. On the other hand, the molybdenum and silver will be very valuable sources of byproduct income which at current prices could cover operating costs.
Metallurgically the concentrate is likely to be relatively complex. It will contain arsenic which could well incur smelter penalties in the early years because of the enargite (Cu3AsS4) in the top of the deposit. The zinc and antimony are unlikely to be a problem. A more serious problem is the presence of variable quantities of talc which come out with the copper/molybdenum concentrate and tend to depress the copper grade of the concentrate. Sodium carboxymethylcellulose (CMC), will suppress the talc in the flotation process but it has the unfortunate side effect of reducing molybdenum recovery. It gives a higher grade copper concentrate but also lower recovery. A high grade copper concentrate is very desirable because smelters generally deduct 1% from the copper content which is a higher percentage of a low grade concentrate than a high one.