The move will allow the company to replace ageing production lines with newer technology, including a high-performing 600 kiloampere (kA) potline, and will keep its total capacity roughly the same,

Hongqiao, which has licensed capacity of 6.46 million tonnes per year of aluminium, closed 2.68 million tonnes of illegal capacity in mid 2017, after being ordered to do so by the provincial government in eastern China's Shandong.

It will disassemble 543,000 tonnes of capacity this year and replace it with 542,000 tonnes, according to an April 15 document published by Shandong's Department of Industry and Information Technology.

China's Ministry of Industry and Information Technology allows aluminium companies to replace or acquire smelting capacity as long as they stay within quotas.

Hongqiao's "new" capacity is part of the 2.68 million tonnes shut in 2017, the two sources said, declining to be identified because they were not authorised to speak to the media.

Hongqiao referred questions to a note by Chinese brokerage Industrial Securities, which also said the new capacity belonged to that shut in 2017, but declined further comment.

The capacity to be replaced will be dismantled from June to December this year, according to the Shandong government document, which says the new capacity can start up when a corresponding amount has been removed.

Despite the switch, Hongqiao's production guidance for 2019 is still a very high 6.3-6.35 million tonnes of aluminium, according to the Industrial Securities note.

Hongqiao said in February around 100,000 tonnes of aluminium production was affected by curbs on industrial output during the 2018/19 winter.

Chinese aluminium consultancy Aladdiny said in a note this week it understood Hongqiao had restarted less than 200,000 tonnes of the annual capacity it closed for the winter because of the impending capacity replacement.

(Reporting by Tom Daly; Editing by Mark Potter)

By Tom Daly