Copper prices have been rising steadily this year, and the trend shows no sign of ending as demand continues to be firm while supply fears grow.
Yesterday, the commodity hit US$8,580 a tonne, an increase of 12 per cent since the start of the year.
Kazakhmys, Kazakhstan's largest copper producer, said sales from continuing operations jumped 10 per cent last year as copper prices advanced.
The increase can be partly linked to the general optimism, largely arising from positive news out of Asia and the United States, that has helped global equity markets to rally since the start of the year.
Employers in the US are thought to have hired an additional 200,000 employees per month for three straight months, which suggests confidence is high that the fledgling American economic recovery will continue.
In China, which uses 40 per cent of the world's copper, inventories in warehouses monitored by the Shanghai Futures Exchange rose to their highest in nearly a decade, potentially suggesting oversupply.
But China's factory sector grew more than expected last month as export orders expanded for the first time in four months, and many analysts are still expecting the country to gobble up its current supplies and demand more. At the same time, news about restrictions to supply is helping to support higher copper prices.
Environmental authorities in Zambia on Saturday ordered the immediate closure of a plant controlled by the Swiss commodity trader Glencore, after health complaints from local residents.
Zambia is Africa's biggest copper producer. The plant is to remain shut until all health concerns have been addressed.
Last month, the financial report of the international mining group Anglo American revealed the company's copper production was 4 per cent lower last year than in 2010 because of extreme wet weather and operational problems at the Collahuasi mine in Chile.
Rio Tinto, the world's third-largest miner, said it expects copper markets to remain tight.