Recycling technology set to target world’s biggest iron smelting waste stock

Technology that harvests blast furnace waste and converts it into an ingredient for cement is being trialled for commercialisation in China, where 60 per cent of the world’s iron waste is produced.

The process, dubbed “dry slag granulation” (DSG), produces a “glassy” product that is said to be ideal for cement manufacture but with significantly lower associated greenhouse gas emissions than cement produced by conventional methods.

Its developers at CSIRO, Australia’s national science agency, have just signed an agreement with the Beijing MCC Equipment Research & Design Corporation (MCCE) to demonstrate the technology at industrial scale.

“Our collaboration is an exciting step towards the uptake of an innovation with real prospects of transforming the productivity and environmental performance of global iron smelting,” said Jonathan Law, CSIRO director of the Mineral Resources Flagship, in a statement.

“The benefits from wide uptake of DSG technology on blast furnaces will be profound in helping the global industry to reduce water and energy use and greenhouse gas emissions while sustaining metal production.”

The DSG technology fitted to blast furnaces includes a spinning disc and granulation chamber that separates molten slag into droplets under centrifugal forces, uses air to quench and solidify the droplets, and extracts a granulated slag product as well as heated air.

Air at 500-600°C extracted from the DSG process can be used onsite for drying, preheating or steam generation.

Researchers claim the technology can also save water and eliminate the underground water pollution that can be associated with alternative wet granulation processes.

“The benefits each year from full commercialisation and adoption of DSG technology are in the order of 60 billion litres of water, 800 petajoules of heat energy and 60 million tonnes of greenhouse gas emissions,” said Law.

“Those savings are equivalent to 14 per cent of Australia’s energy use and about 10 per cent of our greenhouse gas emissions each year.”

Under the agreement, MCCE is to scale-up and demonstrate the technology at industrial scale and commercialise it in China and then potentially worldwide.

The agreement is the culmination of more than a decade of DSG technology development by CSIRO and industry partners including Arrium and BlueScope.