Mr Broomhead, who was Orica's chief executive from 2001 to 2005, will replace Russell Caplan as the company's chairman on January 1.

But Asciano said Mr Broomhead was committed to ensuring its sale to Brookfield proceeded and would seek re-election as Asciano's chairman at its annual meeting on November 10.

"Malcolm Broomhead … remains committed to seeing the Brookfield transaction through to completion," an Asciano spokesman said.

"In the unlikely event the transaction does not proceed, Malcolm would remain as chairman and in due course would be committed to a smooth transition."

The Australian Competition and Consumer Commission is reviewing the Brookfield takeover. It is concerned that combining Brookfield Rail network with Asciano's Pacing National rail, would "substantially" lessen competition in general freight and bulk haulage markets.

The consumer regulator is expected to make its decision on the takeover on December 17, by which time Mr Broomhead would have spent more than two weeks on Orica's board.

The explosives maker said Mr Broomhead would start his term as a director on December 1, before assuming the top job a month later.

Investors welcomed Mr Broomhead's return to the company. Its shares closed 1 per cent higher at $16.74 compared with a flat finish for the broader market.

Orica chief executive Alberto Calderon will be familiar with Mr Broomhead's leadership style. Mr Broomhead is a director of BHP Billiton and was on the mining giant's board when Mr Calderon was a senior executive at the company.

Partnership at the heart of success

Deutsche Bank analyst Mark Wilson said a "successful partnership" between Mr Calderon and Mr Broomhead would be "instrumental in improving margins and returns, and thereby restoring shareholder value".

"We view the appointment of Malcolm Broomhead as … positive for the company given his extensive understanding of the business … and his most recent success as chairman of Asciano," Mr Wilson said in a note to investors, adding that when Mr Broomhead was last at the company net earnings increased more than fourfold.

Outgoing chairman Russell Caplan also praised his replacement.

"Malcolm is a highly experienced business leader with extensive experience in industrial and mining companies globally," Mr Caplan said.

"He brings to the board a deep understanding of both the mining and mining services sector, and exceptional leadership skills through every part of the resources cycle."

Mr Caplan said after serving eight years on Orica's board, he believed the time was right for him to leave the company. His retirement comes two months after Mr Calderon unveiled a new operating structure at Orica to make the company more nimble in serving its customers.

The new model is designed to make the heads of Orica's four regional businesses more empowered and accountable. Under the previous regime, Orica's regional executives across its global operations had no access to their division's earnings or costs data, with only the chief executive having access to that information.

"A board and management succession program is critical for any business, and one of the core roles of the chairman.

"Orica has a new, world-class management team in place that is well placed to enable Orica to further build its market leadership."