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SiLeach® is an unparalleled processing environment that efficiently digests and recovers all significant metal values from the minerals treated.

Thus, it can be applied to a wide range of lithium feedstock, with low energy consumption, high metal recoveries and extensive by-product credits.

Further, SiLeach® has applications beyond the recovery of lithium from silicates. It has, for example, been tested on refractory gold ores to remove siliceous gangue material from the ore prior to cyanide recovery of gold. Therefore, SiLeach® could well become the benchmark for extraction of a wide range of metals from silicates.

The fundamentals

During conventional processing, lithium is recovered only from spodumene concentrates, not lithium micas, which until now have been something of a ‘forgotten’ resource.

Conventional processing to extract lithium also incorporates an energy-intensive ‘roasting’ phase, occurring at temperatures of more than 1,000˚C, followed by ‘sulphation bake’, undertaken at about 250˚C. Once the residue produced is cooled and leached with water, only lithium (as a sulphate) is recovered, and it is then further processed to produce lithium carbonate.

Unlike conventional processing, SiLeach® is a hydrometallurgical process, so no roasting phase is required, which reduces energy consumption. Moreover, there is potential for SiLeach® to derive all its energy requirements from waste heat generated during the production of sulphuric acid, which would further reduce operating inputs.

With SiLeach®, a combination of sulphuric acid and halides is used to dissociate the strong bonds in silicate lattices at atmospheric pressure, meaning that only simple mechanical components are necessary to conduct the process. Reactions occur rapidly at about 90˚C, which is also a distinct advantage in terms of constraining plant footprint and reducing capital costs.

Also unlike conventional processing, all metals within the target minerals are soluble in SiLeach®, creating the opportunity to generate significant by-product credits.

Finally, SiLeach® produces very clean lithium solutions, an advantage in terms of the subsequent production of battery-grade lithium carbonate.