Impact Minerals Ltd Annual Report 2023 9 Review of Operations continued METALLURGY Playa One has developed a novel, relatively low-cost hydro-metallurgical process to convert mineralisation of a type as found on Lake Hope into HPA with the potential to produce a purity exceeding 99.99% (4N HPA), generally taken as the industry standard purity for product comparison. Initial bench-scale metallurgical test work on representative material, process design, flow sheet design, and process engineering studies have been completed, leading to significant breakthroughs in mineral processing technology, including proprietary technologies. Figure 7 illustrates the basic process steps in a simplified schematic flow sheet. Impact’s review of this novel process indicates that together with the unique physical and chemical characteristics of the Lake Hope clays, using the Playa One metallurgical process may offer a breakthrough in HPA production with potentially significant cost advantages compared to the processing of kaolin, which is commonly proposed as a source of ore for HPA and is the subject of several on-going studies by other companies. Figure 7. Schematic flow sheet. These advantages include the following: – the naturally occurring micron-sized particles and relatively homogeneous ore require no comminution, grinding, classification, or wet-dry screening. – a simple wash and filtration circuit for upfront processing. – a low-temperature sulphuric acid leach, a generally readily available and cheaper acid than others. – Eliminating the front-end energy-intensive calcination required in the kaolin process, thus significantly reducing energy costs, the flow sheet complexity and CO2 emissions. – Relatively benign waste products. Optimisation of the processing flow sheet is a key focus of the Pre-Feasibility Study and to be completed by mid-2024. Impact will also own a proportional share of the processing technology by earning an interest directly in Playa One Pty Limited via the incorporated joint venture. The expected relatively low cost of mining also allows for significant optionality for the location of the metallurgical plant, which is likely to be located in one of four main population centres (Figure 2).
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