(£1.28bn) in one of the biggest industrial takeovers by a Chinese group in Europe.
The agreement was reached despite a row between China and Norway over the award of the Nobel Peace Prize to Chinese dissident Liu Xiaobo.
Pizzas-to-metals conglomerate Orkla has been looking to slim down its business lines and a sale was widely expected.
Orkla said yesterday the transaction covered Elkem’s silicon-related operations such as Elkem Silicon Materials, Elkem Foundry Products, Elkem Carbon and Elkem Solar, but not the energy unit Elkem Energi.
The acquisition will give BlueStar, a state-run specialty chemicals company backed by US private equity firm Blackstone Group, access to Elkem’s low-emission smelting technology and silicon output.
Elkem produces high-grade silicon for the solar industry and computers among other things.
By its own account it serves about half the world’s demand for silicon used in electronic components.
Its website says its production methods for solar-grade silicon use a quarter of the energy consumed using traditional technology, making it attractive to China.
The deal’s size puts it in the same ballpark as Zhejiang Geely’s $1.8bn purchase of Ford’s Volvo cars unit in 2010 but behind Sinopec’s $7.2bn deal for Swiss Addax Petroleum in 2009.