The engineering house was chosen from a short list of six international engineering firms.
Hatch will facilitate engineering studies for the HPA demonstration plant.
Meanwhile, other activities continue within the design and technology workstream, including the integration of ancillary HPA technologies.
FYI Resources managing director Roland Hill said Hatch was the most suitable engineering group to provide the specialised engineering needed for the HPA project development.
"Hatch's appointment is a significant step in the development of the HPA project as proposed under FYI's definitive feasibility study," he said.
"Hatch has a strong track record of delivering projects requiring specialist design and engineering solutions across multiple commodities and is best positioned to advance the HPA joint development project.
"We believe Hatch will be an ideal engineering service provider on this innovative project."