LONDON/TORONTO – Mining companies and commodities trading houses are expected to table first-round offers by a September 28 deadline for a stake in Teck Resources' Quebrada Blanca copper mine expansion in northern Chile, two sources with knowledge of the matter said.

Canada's Teck has said a development partner could contribute $2-billion for a 30% to 40% stake in the $4.8-billion Phase 2 project, an investment deal it expects to close in the fourth quarter.

Interest is expected to be strong, reflecting lower exploration investment and fewer discoveries since a 2015/16 commodity price crash. Demand for copper is also rising due to the expansion of electricity grids and growing electric vehicles market.

Initial offers are expected from Japanese trading houses Mitsubishi Corp and Sumitomo, two sources said.

Mitsubishi, which recently agreed to raise its stake in the Quellaveco copper project in Peru it shares with Anglo American, declined to comment. Sumitomo was not immediately available for comment.

Japanese trading companies are scouting for mining assets to buy with their growing profit, driven by higher prices for commodities from coking coal and copper to oil and natural gas.

Interested mining companies include Freeport-McMoRan, the world's largest publicly-traded copper company, China's state-owned Aluminum Corp of China (Chinalco), and Canadian base metals miner Lundin Mining, one of the sources said.

Spokespeople for Freeport and Lundin, previous partners at the Tenke Fungurume copper and cobalt mine in the Democratic Republic of Congo, declined to comment. Lundin, which has C$1.5-billion in cash, was recently outbid by China's Zijin Mining Group in a deal for Canadian copper and zinc miner Nevsun Resources .

Chinalco was not immediately available to comment.

Teck owns 90% of the Quebrada Blanca project while Chilean state agency ENAMI holds the remaining stake but is not required to fund project capital spending.

The expansion plan, known as QB2, won regulatory approval in August and is expected to extend the ageing deposit's life by 25 years and substantially boost production to 300 000 t of copper annually from 23 400 t in 2017.

Teck, which also produces zinc, coal, gold and oil, has hired investment banks Rothschild & Co and Toronto Dominion (TD) to run the bidding process, two sources said.

A Teck spokesman said the company does not comment on market rumours or speculation. Rothschild was not immediately available to comment and TD declined to comment.

Teck CEO Don Lindsay said last year that he had held talks about sharing port infrastructure for QB2 with Anglo American, for its neighboring Callahausi copper mine.