The process uses Veolia's HPD evaporation and crystallisation systems - suitable for the clay deposits found in the region. Bacanora said it opted for Veolia's expertise to not only mitigate the project's risks but also to confirm that the technical and commercial process was feasible and scalable.

Veolia tested the process flow sheet, which had been developed during the operation's feasibility study, and simulated the unit operations planned for the lithium project.

The key difference, again, was the site's clay.

"Different from most of the world's lithium, which is produced from hard rock mines in Australia or from brines in South America, the lithium at Sonora is mined from clay — a rare type of deposit with the potential to become one of the world's largest and lowest-cost lithium resources," Veolia officials said.

Integrated to this plant, Veolia said it designed an evaporation circuit with a double crystallisation sequence featuring HPD thermal separation technologies to maximis recovery of potassium sulphate and sodium sulphate, a valuable salt recycled upstream as the reagent in the clay roasting process.

The process ends with ion-exchange purification, solid-liquid centrifugal separation and drying systems; the goal is to achieve greater than 99.5% battery-grade lithium carbonate.

"We are proud to help game-changing miners in search of a partner with the knowhow to produce lithium from a variety of feedstocks," Veolia Water Technologies Americas EVP Jim Brown said.

He noted that the testing programme validated Bacanora's product purity requirements, and also removed potassium and converted a waste stream into a high-value-added fertiliser.

Sonora, located just south of the Mexico-US border, has been designed to reach a capacity of 17,500 tonnes per year of battery-grade Li2CO3 (lithium carbonate) in its initial phase.