High Purity Alumina (HPA) at greater than 99.99% (4N) purity has been produced from the metallurgical processing of lake clays from Impact Minerals Limited’s (ASX:IPT) Lake Hope Project, located 500 km east of Perth in Western Australia (Figure 1). Impact can earn an 80% interest in Playa One Pty Limited, which owns the Lake Hope project, by completing a Pre-Feasibility Study (PFS) on the project which is in progress (ASX Release March 21st 2023 and November 9th 2023).
Better than 99.99% (4N+) High Purity Alumina (Al2O3) produced from Lake Hope mud via the proprietary and patented Playa One Sulphate Process.The Sulphate Process underpins the recent Scoping Study, which demonstrated an NPV8 of A$1.3 billion for the project and an estimated operating cost to produce 4N HPA up to 50% lower than anyone else globally at less than US$4,000 per tonne.Production of larger quantities of HPA can now commence using the now-optimized Sulphate Process to demonstrate consistent quality to potential customers.Preliminary discussions with potential customers indicate very strong demand for 4N HPA.Other possible process routes to produce HPA from Lake Hope may be possible, with initial results due shortly.The Pre-Feasibility is on schedule to be completed in late 2024.
We have also optimized the Playa One Sulphate Process and have already started batch production of HPA to demonstrate consistent quality to our potential customers. We have discovered from our marketing that there is very strong demand for this high-value product, so we will continue progressing the Pre-Feasibility Study as quickly as possible. In addition, we recently uncovered two other possible process routes to produce HPA from these remarkable clays, which may offer yet further reductions in operating cost and capital expenditure if our initial test work is positive, and we are looking forward to getting those results soon,” Dr Jones said.
The 4N HPA was produced via a proprietary and patented metallurgical process called the ‘Sulphate Process’ which is owned by Playa One. The replication and optimization of this process for Lake Hope has been the key focus of Impact’s Pre-Feasibility Study to date, and therefore, these new results are a key milestone in the development of the project (ASX Releases March 21st 2023 and October 18th 2023).
The clays at Lake Hope occur in the top two metres of two small salt lakes on E63/2086 in a deposit containing about 880,000 tonnes of alumina (Al2O3) in various minerals. The deposit comprises Indicated (88%) and Inferred Resources (12%) of 3.5 million tonnes at an average grade of 25.1% alumina (see the Resource Estimate below and ASX Release 19th June 2023).
The lake clays contain a unique combination of naturally extremely fine-grained minerals, which delivers significant cost advantages to the mining and processing of the ore to produce HPA. The clays are free- digging and require no crushing, screening or other on-site preparation, and it is envisaged that the clay will be trucked offsite to a pre-permitted industrial site, most likely either in Kalgoorlie or Perth (Figure 1 and ASX Release March 21st 2023 and November 9th 2023).
The Playa One Sulphate Process is straightforward and comprises five stages based around very modest amounts of sulphuric acid (Figure 2): Stage 1 Wash circuit, Stage 2 Sulphuric acid leach and roast circuit, Stage 3 Intermediate alumina salt production, Stage 4 purification by conventional hydrochloric acid gas sparging and Stage 5 calcining to produce HPA. Results from the optimization of the first three Stages of the Process were reported to the ASX on October 18th 2023.
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