Billionaire mining boss Chris Ellison will leave Mineral Resources as part of an "orderly transition" within 18 months after the company's board found the chief executive had at times used company resources for his personal benefit.
MinRes said in a statement it had also fined Ellison $8.8m to reflect the "significance of corporate governance and reputational issues to the company". The founding chief executive also faces a further $9.6m in lost remuneration.
The mining and services company ordered an investigation into its founder over various allegations including Ellison's decision not to disclose revenue generated by overseas entities to tax authorities before the company was listed; an issue for which the mining magnate has apologised.
The company's chair, James McClements, will also step down at or before next year's annual general meeting, the company said.
Related: Billionaire mining boss says it was 'regrettable' he didn't disclose overseas revenue to ATO
As part of the investigation, a range of issues and shortcomings were identified, MinRes said on Monday.
"With the interests of shareholders absolutely front and centre, the board has determined there needs to be an orderly leadership transition, significant strengthening of governance protocols, and a financial penalty imposed on Mr Ellison," McClements said.
The company said that Ellison did not disclose his private tax settlement with the ATO to MinRes in a timely manner.
Separately, MinRes found that the chief executive, on occasion, used company resources for his personal benefit.
This included: directing company employees to work on his boat and properties, directing a company employee to manage his personal finances; and using the company to procure goods and services for his private use.
"While he has cooperated with the current investigation, over the lifespan of the matters being investigated, on some matters, Mr Ellison has failed to be as forthcoming with the board as he should have been," McClements said.
"There can be no doubt that the actions, decisions and behaviours of Mr Ellison have been profoundly disappointing and require sanction and penalty."
Ellison said in a statement he accepted the board's decision.
"I am deeply sorry for the events that have occurred and the impact they have had on MinRes' reputation," Ellison said.
"I apologise to the rest of the board and to our people, who expect and deserve better from me. I acknowledge that I made mistakes, some of which were driven by my wish to keep private certain events that cause me great personal embarrassment."