Rare earth oxides producer Molycorp will invest an additional $114m in a rare earth processing facility, which is under construction at Mountain Pass in California, US.

With this investment the firm is planning to speed up the initial start-up of the facility by three months.

The initial start-up of the facility will enable Molycorp to achieve its full phase one production rate of 19,050 metric tons a year of rare earth oxide.

It will also increase the firm’s production capacity for 2012 by 3,500 metric tons, to between 8,000 and 10,000 metric tons.

The firm will commence mining and stockpiling of fresh rare earth ore in the coming week.

Molycorp president and CEO Mark Smith said accelerating the start-up will de-risk the overall project by allowing for a more orderly and sequential start up of the various circuits of the highly complex plant.