Recycling plan for Kurri Hydro spent pot linings

The high carbon-content spent pot liners have been used elsewhere in the world to fuel furnaces that make ­mineral wool insulation sold here as Earthwool and Rockwool. 

Kurri Kurri resident and Hydro ­community reference group member Col Maybury flagged the option during site remediation discussions on Thursday night.

“Earthwool would be the perfect product to use spent pot liners,” Mr Maybury said.

Knauf is one company, he noted, that already used SPL to make mineral wool under the Earthwool brand.

A UK industry paper also endorsed SPL as an alternative fuel source for mineral wool manufacture in 2007.

During this process, rock is melted in a furnace at 1500 degrees Celsius with a fuel source, which is usually coke.

The molten material is then spun like wool to form the insulation.

Authors of the industry paper noted that SPL was a more cost-effective ­alternative to coke as fuel source.

Scrubbers were used to filter ­emissions from the furnace and capture the fluoride released from the SPL. 

Even with the price of scrubbers, SPL was still a more cost effective ­alternative than coke.

Mr Maybury said he had written to Knauf to investigate this avenue and hoped to report his findings to the group soon.

The suggestion was met with interest among group.

“It’s an option,” Hydro Kurri Kurri managing director Richard Brown said.

“I imagine other Rockwool ­manufacturers have similar processes.”

Mr Brown said SPL was not a money spinner for Hydro even though it had industrial uses and was a component in some commercial products.

“They don’t sell it and make money of it,” he said.

Group members laid down criteria to assess recycling options when tenders are opened.

Weston Aluminium and Regain were expected to apply for the recycling contract.

Until this month, Hydro had proposed to bury the 80,000 tonnes of SPL in a purpose-built containment cell, along with other refractory waste it will extract from an old stockpile known as Mt Alcan.