Mr Cosgrove also asked why Mr Ryall took "no action" to address problems at the company despite receiving monthly reports on it from June last year onwards.
Mr Ryall said Mr Cosgrove's allegations were not correct.
He earlier told Parliament that when ministers became aware of Solid Energy's problems in late 2011, "we took the appropriate steps to address the issues that were raised.
"The company now has a new chair and new board, and we are currently dealing with the banks to resolve those issues."
Mr Palmer, who is now in his final few months as Air New Zealand chairman, has remained silent on Solid Energy's problems since they were revealed last week.
He announced his resignation in June last year and officially stepped down on August 31 - the same day he fronted the company's announcement of a $40 million loss. His departure came 16 months ahead of schedule.
Dr Elder resigned at the beginning of this month, 2 weeks before the Government revealed Solid Energy was $389 million in debt and was trying to stitch together a restructuring plan.
Mr Key yesterday listed steps Solid Energy took to diversify away from simple coal production which were made under the previous Labour Government.
But Labour leader David Shearer said Mr Key needed to "man up and take responsibility for the collapse of this company".
With the partial sale of Solid Energy off the agenda for the time being, Mr Shearer said there was now no way the Government could make the $5 billion to $7 billion from the mixed ownership model.
Finance Minister Bill English said the proceeds from the programme may have to be revised downwards in the Budget.
Mr Key later told Parliament that based on 2011 estimates the sale of 49 per cent of Solid Energy would have raised $680 million to $850 million.