A key step in the sale of Arrium's troubled Whyalla steelworks has begun with local workers and miners facing a possible pay cut.

Formal negotiations over a new Enterprise Bargaining Agreement (EBA) will begin in Whyalla today between union representatives and the company's administrator, KordaMentha.

KordaMentha took over administration of the company earlier this year as the steelworks struggled with about $4.3 billion in debt.

Australian Workers Union's Peter Lamps said a 15 per cent pay cut would be the main agenda item discussed.

"From the union's perspective that hasn't been agreed to at this time but all the parties are prepared to engage in a mature conversation to see if that ask can be arrived at," he said.

He said workers were showing resilience during difficult times.

Mr Lamps said negotiations could take weeks.

In March, miners for the company rejected any pay reductions after Arrium asked them to take a temporary cut of 10 per cent until it could afford to pay them their normal salaries again.

A month later the business went into voluntary administration.

KordaMentha has previously flagged it would put the steelmaker on the market in late July.