Rio Tinto starts cleaning up Tiwai Point
From Stuff - reporter Rachael Kelly
Rio Tinto will begin exporting a hazardous substance which is being stockpiled at Tiwai Point, as the company begins cleaning up the site where it has produced aluminium for more than 50 years.
The company came under pressure to clean up the smelter site after it was revealed it has been stockpiling potentially toxic waste in storage facilities and a landfill.
Despite the possibility that the smelter may stay open past its 2024 closing date, New Zealand Aluminium Smelter chief executive and site general manager Chris Blenkiron said regardless of the closure date or plan for the operation at Tiwai Point, Rio Tinto and NZAS are committed to remediating the site.
”We are not waiting, right now we are working closely with Ngāi Tahu, Environment Southland and the Ministry for the Environment on achieving the best outcomes,” he said.
The company has 217,000 tonnes of spent cell lining in two storage facilities at its site near Bluff. Some is in a purpose-built building, and 106,000 tonnes is being stored on an engineered concrete pad with purpose-built drainage. The pad is about 100m from a beach which is being affected by coastal erosion.
Spent cell lining is made up of carbon refractory bricks, which are used in the aluminium-making process for five to six years. They contain fluorides, cyanides and nitrides, and can produce explosive gases when mixed with water.
Blenkiron said contracts were in place to begin exporting spent cell lining to industrial end users.
SCL is exported for use in the cement industry and is also used in the manufacture of ceramics. The company could not say when the exporting would begin.
As well as removing ouvea premix from the paper mill at Mataura, the company has also cleared two other sites of the class six toxic substance, which produces ammonia gas if it gets wet. Two more sites are yet to be cleared.
Nearly 15 thousand tonnes of ouvea premix, a by-product of the aluminium smelting process, has been removed from sites around Southland to date, with around 9000 tonnes still to be removed.
Rio Tinto will spend a total of $6 million removing the toxic chemical from warehouses in Southland. Taha Asia Pacific stored 10,000 tonnes of premix in the former paper mill, and another 10,000 in warehouses in Invercargill before it went into liquidation in 2016.
Rio Tinto is also adopting new processes to reduce risk at the smelter site, such as the development of a dry process to clean out the base of reduction cells, which removes the use of water in this process.
In March last year Environment Minister David Parker admitted there was no agreement in place between the Government and Rio Tinto to clean up the site at Tiwai Point, where the smelter has operated for 40 years.
Rio Tinto and senior government ministers have discussed changing the mining giant’s plan to close the Tiwai Point aluminium smelter in 2024, but documents released under the OIA make clear that the date for closing the smelter, which currently employs about 1000 staff and contractors, is not “final”.
This week, Meridian opened the door to negotiations that could see the Tiwai Point aluminium smelter stay open for at least another 12 years until 2034.
Posted: 26 February 2022