The increased demand for lithium in recent years — driven mainly by battery manufacturing — has broadened the scope of lithium-processing technologies. Typically, lithium is mined from spodumene ore or sourced from brine deposits, but a new process enables lithium’s recovery from mica minerals — a typically overlooked raw material. Lepidico (Perth, Western Australia; www.lepidico.com) is currently in the process of scaling up its L-Max technology (see diagram) for processing lithium-bearing micas and phosphate minerals. What sets L-Max apart, according to Joe Walsh, Lepidico’s managing director, is its proprietary impurity-removal steps, which result in several salable byproducts and very little waste. “A number of those impurity removal stages, for instance, the removal of potassium, result in a byproduct. We’ve tried to add as much value as we can by producing salable materials as we step through the process,” says Walsh.
L-Max begins with a relatively conventional sulfuric-acid leach followed by crystallization and subsequent filtration and purification steps, finally resulting in the precipitation of lithium carbonate. Walsh points out that the process is particularly adept at handling potentially problematic impurities, especially fluorine. “The fluorine stays in solution until a certain pH range is reached, at which point a benign compound, aluminum fluoride, is formed. This makes it the most sustainable and promising mica-based process technology in terms of its health and safety attributes,” adds Walsh.
The L-Max process has undergone mini-plant trials operating at 1–1.5 kg/h, with continuous closed-loop operation for about a week at a time. The team is currently constructing a 15-kg/h pilot plant, located in Perth, which is set to be commissioned in April 2019. Concurrently, feasibility studies are underway for a larger “Phase 1” plant, which will be designed to produce around 5,000 metric tons/yr of lithium carbonate. Lepidico is considering locations in Ontario, Canada for the Phase 1 plant.