King River Resources Limited provided the update on the ongoing laboratory work as part of the advancement of the High Purity Alumina (HPA) Project. As reported on 19 April 2022 the company Board placed the Detailed Feasibility Study for the 2000tpa 5N Aluminium Salt Precursor 1 plant on hold, to capitalise on HPA process development. Laboratory process development testwork remains ongoing identifying and refining new process improvements to its ARC HPA process, which may provide potentially more economical options and pathways and a more environmentally friendly process route to the production of HPA.

Process Advancements: Laboratory testwork by Source Certain International (SCI) has been systematically working on three processes pathways for HPA to improve the project economics and environmental, social and governance (ESG) benefits in comparison to the process pathway that was being used for the initial HPA Pre-Feasibility Study (PFS) and the Type: 1 Precursor Detailed Feasibility Study (DFS). ARC - 1. This is a modification of the original ARC HPA process outlined in the PFS. It uses an Aluminium (Al) chemical feedstock and initially produces the 5N purity Al salt by recrystallisation as demonstrated in its DFS campaign tests.

The Al salt is then converted to Al Hydroxide which is calcined to HPA. This process requires high purity reagents and produces by-products that are either neutralised or processed for recycling. The benefit of this process is that it requires no off-gas treatment as only water is given off in the calcination process.

ARC - 2. This is a new process that was introduced to address the reagent and waste issues highlighted by the ARC 1 process. It also uses an Al chemical feedstock and is still under development. The initial recrystallisation purification stage uses a different reagent that can be recycled more directly.

Testwork has produced a high purity Al salt and is ongoing to improve purity, reduce the purification steps and increase overall recovery. The Al salt produced can then be converted to Al hydroxide prior to calcination to HPA. The benefits of this process are that it requires no off-gas treatment, produces less waste and has better recycling opportunities.

ARC - 3. This new process uses an Al chemical feedstock but takes a completely different approach that requires no precipitating reagents and produces no reagent related wastes. In addition it produces Al Hydroxide directly for calcining into HPA. The process is still under development.

These new process routes are the current focus of KRR HPA research and their discovery has contributed to the company's change in direction and the extension of the laboratory research programmes. Type 1 Precursor: Detailed Feasibility Study: Based on the laboratory developments the DFS in its current form is not the commercial solution required by the company. The work that was completed provided a foundation of understanding on the Capital and Operating costs associated with this size of plant in such a modular flow sheet design.

This information will be beneficial in expediently assessing the commercial opportunities of the new process pathways.