As the world’s hunger for energy reaches dizzying heights, lithium and its chemical compounds continue to make large strides on the commodities market due to their wide range of industrial applications, especially in their use in lithium-ion batteries (LIBs).

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Lepidico’s L-Max® process technology is turning mining waste to battery-grade lithium and potash

As night follows day, so is an increase in world-wide demand for lithium followed by an increase in lithium mine wastes that are volumetrically one of the world’s largest waste streams. But what if those wastes could be converted into battery-grade lithium and potash?

A Brisbane/Perth-based lithium company, Lepidico, has developed L-Max® process technology, which has the potential to commercially extract lithium chemicals for the burgeoning electric battery market.

Currently, lithium is obtained from two major sources: brines and hard rock spodumene. There exist, however, other lithium-rich minerals including lepidolite, zinnwaldite and amblygonite, which have been discarded and overlooked as potential sources. These untapped sources of lithium often co-exist with spodumene or tantalite in pegmatite deposits and are sometimes mined and discarded to tailings.

“These minerals have previously been considered ‘waste’, when found within pegmatite deposits containing other lithium minerals such as spodumene, or of geological curiosity only,” commented Gavin Becker, Lepidico General Manager – Business Development.

Lepidico is expecting to bring on-stream an additional ‘leg’ of cost competitive lithium supply to the battery industry by processing lithium mica and phosphate mineral concentrates using its proprietary L-Max® technology.

“When drilling hard rock deposits, such as pegmatites containing lithium ores, it’s very important to identify the lithium minerals that are present rather than just report lithium assays,” continued Mr Becker.

“Often, for example, a significant proportion of the lithium is not in the conventionally desirable or target spodumene mineral but in other lithium containing minerals, including micas and phosphates, that could not or should not be recovered into a saleable spodumene product.

“Such micas and phosphates would contaminate the spodumene product unless removed, resulting in a loss of recoverable lithium potential. L-Max® turns this problem into an opportunity.”

Earlier this year, Lepidico announced that it had successfully produced battery-grade lithium carbonate grading 99.8 per cent, using its L-Max® process technology from a tailings stream sourced from the Galaxy Resource Mt Cattlin spodumene operations.

Hydrometallurgical batch tests have been completed on a secondary float (“tailings”) sample sourced from the Mt Cattlin Dense Media Separation plant. A tailings sample was provided for the testwork, which graded 2.7 per cent Li2O. From this, a flotation concentrate was produced grading over 4.0 per cent Li2O. Lithium recovery to concentrate was 96.6 per cent.

The sample was then subjected to leaching under standard L-Max® conditions, with extractions for lithium of approximately 94 per cent. Higher extractions are expected by undertaking an optimisation program to achieve rates similar those achieved in tests conducted on other lithium mica samples which realised over 98per cent extraction.

The leach liquor from the test was subjected to the usual L-Max® downstream process flowsheet in a series of batch tests. Lithium losses in the post leach L-Max® process were estimated at 4 per cent, with total recovery from flotation concentrate to final product of over 90per cent.

Optimisation testwork specific to Mt Cattlin is being evaluated to maximise lithium and by-product extractions, while minimising acid and power consumption.

“This testwork programme demonstrates conventional flotation coupled with Lepidico’s proprietary L-Max® process technology can be used to produce battery grade lithium carbonate from modest lithium grade tailings sourced from primary spodumene operations”, said Lepidico’s Managing Director, Joe Walsh said.

“This work implies that L-Max® can materially enhance the Mineral Resource potential and thereby value of mixed lithium mineral hard-rock deposits that contain lithium-micas.”

Mr Becker sees the positives of L-Max® to be numerous and complimentary.

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L-Max® process technology mini plant run

“L-Max® utilises low-cost ‘nuisance’ sulphuric acid from smelters to allow treatment of previously under-appreciated lithium minerals for the production of battery grade lithium at low nett cost. Because numerous by-products are also produced and sold into adjacent markets, the process results in a relatively benign environmental footprint.”

Following the success of L-Max®, Lepidico has lodged a provisional patent application for a hydrometallurgical process, S-Max™, developed in close collaboration with Strategic Metallurgy – inventor of the L-Max® process.

S-Max™ produces an amorphous silica from concentrates sourced from a range of mica minerals, including lithium micas. The purified amorphous silica may be sold directly or used as a feed to produce a variety of other marketable silica products.

S-Max™ employs three stages; grinding, sulphuric acid leach regimes at atmospheric pressure, followed by differential classification and flotation streams, and can be integrated with L-Max® process.

When lithium bearing mica concentrates are treated, the S-Max™ leach liquor can feed directly into the first impurity removal stage of the L-Max® process. Furthermore, the leach liquor from non-lithium bearing micas including muscovite and biotite may be treated to produce valuable by-products including sulphate of potash (SOP) fertiliser. When combined with L-Max® silica production costs are expected to be extremely competitive.

“S-Max™ has been more than a year in the making and is a complementary process to L-Max®,” said Mr Walsh.

Lepidico is in the process of completing a Feasibility Study into its first Phase 1 Plant to be located in Sudbury, Ontario, Canada. It is of a size considered to be commercial but is approximately 20 per cent of what would be considered a full-scale plant.

Subject to demonstrating to the market the quality and low-cost nature of L-Max® via the Phase 1 Plant, future full-scale plants would be best located in or near the Great Lakes Megalopolis, mainland Europe, coastal Japan/Korea/China, and perhaps ultimately in Australia.

“S-Max™ is being integrated into the engineering design for the Phase 1 Plant Project in Sudbury and is expected to lead to reduced consumable consumption rates, higher recoveries of lithium and potassium, and the production of a broader suite of silica products than L-Max®,” said Mr Walsh.

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