A former BHP Group veteran has warned West Australian regulators against limiting emissions at iron ore operations, adding that allowing a small increase in emissions for stripping out impurities in Australia could lead to a substantial emissions cut at Asian mills.

Allon Brent, who retired from BHP in 2016 after 27 years at the company where he was most recently its iron ore marketing manager, on July 22 told the Australasian Institute of Mining and Metallurgy's Iron Ore 2019 conference in Perth, Australia, that using better quality iron ore in steelmaking plants lowers emissions downstream.

The comments come as Western Australia's Environmental Protection Authority seeks input for a set of revised guidelines on greenhouse gas emissions for "significant" new projects.

"It's more efficient to remove the gangue [the uncommercial impurities in iron ore which are mainly alumina and silica] at room temperature with water in the Pilbara than to flux and melt it out at 1,450 degrees Celsius in Asia," Brent, who now heads up local consultancy Global Minerals Marketing, said.

To explain his case, Brent calculated the potential beneficiation of a typical high-phosphorus 61% Brockman fines iron ore produced by Rio Tinto to decrease the alumina content from 3% to 2.2%.

He then ran a simulation of an average Asian steel mill using what the World Steel Association says was the average carbon dioxide generated by iron ore production, which was 8 kilograms of carbon dioxide per wet tonne of iron ore. However, he doubled the 8 kilogram figure to cover the carbon dioxide produced in railing and port handling, to get an overestimate.

Global Minerals Marketing Principal Allon Brent addresses AusIMM's Iron Ore 2019 conference. Source: AusIMM/CSIRO

Reducing the alumina content resulted in a net carbon dioxide reduction downstream of between 12 kilograms per tonne of iron ore and 80 kilograms per tonne, depending on the blast furnace used.

"If we potentially make a small [carbon dioxide] investment in beneficiation in Western Australia to improve ore quality, it could lead to a substantial [carbon dioxide] payback in Asian steel mills," Brent said.

"This leads to the counterintuitive notion that actually increasing emissions in Australia could result in a net decrease in net greenhouse gas emissions," he said.

"The corollary is also true — if we set targets for our iron ore producers to reduce their greenhouse gas emissions, let's say by half a kilogram per tonne of iron ore, it could lead to a 30 kilograms to 50 kilograms per tonne increase in the steel mill."

Thus, in the context of the review on emissions guidelines by the Western Australian environmental watchdog, he said it was important to consider how any targets set will impact iron ore producers' scope three emissions.

Scope three emissions are those generated as iron ore customers — in this case the steel mills in Asia — transport, transform and use the product

Brent also added that not all ores are beneficiable, but the topic warrants further research.

BHP CEO Andrew Mackenzie said in London on July 23 that the company would set public goals in 2020 to address scope three emissions, most of which come from the production of recyclable goods.

He said BHP would scale up low emissions technologies that decarbonize its operations which will drive investment in "nature-based solutions" and encourage further collective action on scope three emissions.