Rio Tinto completes transition of heavy machinery to renewable diesel at US California borax site

Article by Amanda Jasi

Angel DiBilio /
Sinead Kaufman, chief executive of minerals at Rio Tinto, expects that the transition at the company's California borax operation will lead to opportunities for global decarbonisation.

RIO Tinto has completed the full transition of heavy machinery from fossil diesel to renewable diesel at its borax operation in Boron, California, US. The mining giant said this is the first open pit mine in the world to achieve this milestone.

At the site operated by US Borax, Rio Tinto’s borax business, all heavy machinery was converted to the new fuel, from haul trucks to loaders – the renewable diesel is even used in blasting. The company expects that the change to renewable diesel will reduce emissions of CO2 equivalent by up to 45,000 t/y.

The full transition follows a switching trial conducted in partnership with Neste and Rolls-Royce through 2022. During the trial, a haul truck at the California operation used Neste MY Renewable Diesel, a hydrotreated vegetable oil that is made from 100% sustainably sourced renewable materials such as cooking oil and animal fat waste from the food industry. It is compatible with diesel engines and existing diesel distribution infrastructure. Use of the renewable diesel can reduce greenhouse gas (GHG) emissions by up to 75% over the life cycle of the fuel compared to fossil diesel.

The results from the trial showed that a truck running on the renewable diesel delivers similar performance and reliability to trucks running on conventional diesel. Following the positive results, US Borax continued to work with Rolls-Royce, Neste, the US Environmental Protection Agency, and the State of California to achieve the full transition at the end of May 2023.

Sinead Kaufman, chief executive of minerals at Rio Tinto, said: “We are proud that our US Borax operations have become the first open pit mine to operate a fleet running entirely on renewable diesel. This is an excellent example of what happens when internal and external partners collaborate toward a carbon reduction goal. Support from the state of California has also been incredibly important, as without their vision, this would not have been possible.”

“The transition at Boron is an important first step and will undoubtedly lead to further opportunities to decarbonise our global operations. Renewable diesel is one of several sustainability solutions that Rio Tinto is using to transform its businesses.”

Last October, a second conversion trial was launched at Rio Tinto’s Kennecott Bingham Canyon mine in Utah, US, in collaboration with vehicle component manufacturer Cummins, to test renewable diesel in a different operational environment and on different mining equipment. It is to compare acceleration, speed, cycle times, fuel use, and engine inspection reports for two trucks running on renewable diesel, to two running on conventional diesel, complementing the data collected in California.

Rio Tinto said conversion to renewable diesel supports its decarbonisation objectives, which include reducing its scope 1 and 2 emissions 50% by 2030, compared to the 2018 baseline of 32m t/y, and achieving net zero by 2050. The company estimates that carbon emissions from the use of diesel in its mobile fleet and rail accounted for 13% of its scope 1 and 2 emissions in 2022, which totalled 30.3m t/y.

Article by Amanda Jasi

Staff reporter, The Chemical Engineer

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