US-based engineering group Bechtel won the main contract on Bahrain’s planned $3.5bn aluminium smelter expansion, according to project owner Aluminium Bahrain (Alba).

Alba awarded the engineering, procurement and construction management (EPCM) to Bechtel for its line 6 expansion project, which will see the US company design and construct a sixth potline and support industrial services.

Bechtel won the EPCM contract on the previous fourth and fifth potline expansions.

The project will make Alba the world’s largest single-site aluminium smelter, boosting the site’s production capacity by 540,000 tonnes a year (t/y) to 1.5 million t/y. The smelter will overtake Emirates Global Aluminium’s (EGA) Abu Dhabi smelter as the largest in the Middle East.

The sixth potline will have 424 pots that will use the proprietary EGA DX+ Ultra technology.

Alba was granted government approval for the project in the second quarter of 2015. The expansion is expected to be completed in 2019.