The wife of federal MP Clive Palmer has replaced his nephew as director of his flagship mining company Mineralogy.

Documents lodged with the Australian Securities and Investments Commission (ASIC) show Anna Palmer was appointed director and secretary of the company two weeks ago.

She replaced Clive Mensink, who is the director of Mr Palmer's troubled Queensland Nickel.

The change occurred 10 days before Queensland Nickel went into voluntary administration, citing low nickel prices and the Queensland Government's refusal to guarantee a $35 million loan.

That announcement came days after the company sacked 237 workers.

Mr Palmer has reportedly sent a letter to his former employees apologising for the redundancies.

On Wednesday, the Federal Government offered $500,000 to help the sacked workers find new work.

If the company cannot trade its way out of voluntary administration, taxpayers could also be forced to stump up tens of millions of dollars to clean up the site at Yabulu.

While Queensland Government sources have claimed the process could cost up to $40 million, the Queensland Opposition has said the clean up bill could be "upwards of $300 million".