Duro Felguera will work with Australia's Primero Group, the nominated engineering firm in the contract, on the second phase of early contractor involvement in the engineering, procurement and construction (EPC) of the plant.

DF and Primero are expected to undertake the work between August 2020 and November 2020, with the Spanish Export Credit Insurance Agency (CESCE) to provide financing for up to 85% of the amount of the FEED contract.

Duro Felguera and its partner will perform detailed engineering, enhancing and improving the design and efficiencies in the processing plant, and complete all of the work involved in the EPC contract, at a guaranteed maximum price totalling US$58 million.

"We are extremely pleased to have Duro Felguera and Primero as our EPC partners. The fixed price lump sum turnkey EPC contract will mitigate cost overrun risks for our Grota do Cirilo project," said Sigma's chief executive, Calvyn Gardner.

"The combination of their significant experiences will help Sigma manage construction risk at the project: DF has a successful track record of managing lump sum turnkey fixed price EPC contracts in Brazil and globally. Primero will bring its vast experience in building state of the art lithium processing plants in Australia." 

Duro Felguera also brings to the project the financial support of CESCE, enabling the start of detailed engineering and EPC work already in August, said Gardner.

Grota do Cirilo aims to be a larger-scale lithium concentration commercial production plant with a potential capacity of 220,000 tonnes annually of battery-grade low-cost lithium concentrate.