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Rio Tinto targets low-carbon steel with novel biomass and microwave tech

In Australia, Anglo-Australian global mining major Rio Tinto Ltd has announced that it is progressing an innovative new biomass and microwave technology to deliver low-carbon steel, using sustainable biomass in place of coking coal in the steelmaking process. This, the company says, is a potentially cost-effective option to cut industry carbon emissions.

Anglo-Australian global mining major Rio Tinto Ltd has is progressing an innovative new biomass and microwave technology to deliver low-carbon steel, using sustainable biomass in place of coking coal in the steelmaking process. This, the company says, is a potentially cost-effective option to cut industry carbon emissions.

Over the past decade, Rio Tinto has developed a laboratory-proven process that combines the use of raw, sustainable biomass with microwave technology to convert iron ore to metallic iron during the steelmaking process.

The patent-pending process is one of a number of avenues the company is pursuing to try to lower emissions in the steel value chain and is now being further tested in a small-scale pilot plant.

If this and larger-scale tests are successful, there is the potential for this technology to be scaled commercially to process Rio Tinto’s iron ore fines.

We are encouraged by the early testing results of this new process, which could provide a cost-efficient way to produce low-carbon steel from our Pilbara iron ore. More than 70 percent of Rio Tinto’s Scope 3 emissions are generated as customers process our iron ore into steel, which is critical for urbanization and infrastructure development as the world’s economies decarbonize. So, while it’s still early days and there is a lot more research and other work to do, we are keen to explore further development of this technology, said Simon Trott, Chief Executive, Rio Tinto Iron Ore.

Lignocellulosic biomass and microwaves

Rio Tinto’s process uses lignocellulosic biomass, instead of coal, primarily as a chemical reductant. The biomass is blended with iron ore and heated by a combination of gas released by the biomass and high-efficiency microwaves that can be powered by renewable energy.

Rio Tinto researchers are working with the multi-disciplinary team in the UK’s University of Nottingham’s Microwave Process Engineering Group to further develop the process.

It is really exciting to have the opportunity to be part of a great team working on a technology that if developed to commercial scale, has the potential to have a global impact through decarbonizing key parts of the steel production process, said Professor Chris Dodds, Head of Department, Chemical and Environmental Engineering, University of Nottingham.

The use of raw biomass in Rio Tinto’s process could also avoid the inefficiencies and associated costs of other biomass-based technologies that first convert the biomass into biocoal or biogas.

Lignocellulosic biomass includes agriculture by-products such as wheat straw, corn stover, barley straw, sugarcane bagasse, and purpose-grown crops, which would be sustainable sources for the process.

The process cannot use starches or sugars, and Rio Tinto is committed to using biomass sources that do not come from logging of old-growth forests.

We know there are complex issues related to biomass sourcing and use and there is a lot more work to do for this to be a genuinely sustainable solution for steelmaking. We will continue working with others to understand more about these concerns and the availability of sustainable biomass, Simon Trott said.

If developed further, the technology would be accompanied by a robust and independently accredited certification process for sustainable sources of biomass.

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