Calix (ASX:CXL) said Rio Tinto Group (ASX:RIO) agreed to provide over AU$35 million in support for the demonstration of its zero-emissions steel technology in Western Australia, according to a Monday filing with the Australian bourse.

As part of the project, a "green" iron demonstration plant will be built in Kwinana.

The support, which is a combination of AU$8 million in cash and further in-kind contributions, will also be used for the future commercialization of the decarbonization technology, the filing said.

Once the project reaches a final investment decision, Rio Tinto will provide up to 10,000 tonnes of a range of Pilbara iron ores, and introductions to potential users of Calix's "green" iron product, the filing added.

Calix said it retains the right to provide the technology under license to other partners.