Impact Minerals Records Low Uranium-Thorium and 4N Purity in Lake Hope HPA samples

Impact Minerals (ASX: IPT) has reported independent high-sensitivity assays for four high-purity alumina (HPA) samples produced from Lake Hope feedstock via the patented low temperature leach (LTL) process that underpinned the project’s 2025 pre-feasibility study (PFS).

Analysis by globally recognised Eurofins EAG Laboratories returned one sample with uranium and thorium below the analytical detection limit of 1 part per billion, two samples with thorium at or below 1ppb and uranium at 4ppb and 10ppb, and one sample with thorium at 10ppb and uranium at 9ppb.

In addition, three samples achieved 4N HPA purity (>99.99% aluminum oxide) with total measured impurities of less than 100 parts per million and the best sample achieving 4N5 across a wide range of impurities.

The fourth sample achieved 99.977% aluminum oxide after refinements to the initial caustic leach reaction and showed lower phosphorus, magnesium and potassium concentrations.

The results will be used for pilot-scale development and process optimisation through Impact’s three-year research program with Edith Cowan University.

Industry Thresholds Met

Lake Hope’s results meet industry thresholds for “low-alpha” and “zero-alpha” alumina used in advanced semiconductor packaging and thermal management applications.

As semiconductor architectures become more complex and tolerance for errors decreases, radioactive impurities in materials located close to chips and memory devices must be removed to prevent radioactive decay that may cause data errors or device failures.

To achieve these levels, extensive research and development programs have been required to develop additional processing steps to remove uranium and thorium (or radionuclides).

Importantly, Lake Hope’s low-alpha HPA was produced using the patented LTL process, without a dedicated step to remove these elements.

Continuous Refinement

Impact managing director Dr Michael Jones said LTL would be continuously refined to produce the best results from Lake Hope.

“The standout feature to date is the exceptionally low uranium and thorium content achieved directly from the Lake Hope flowsheet, without a dedicated radionuclide-removal stage,” he said.

“We believe this is an excellent starting point for engaging with the semiconductor industry, where ultra-low-alpha radiation alumina is required for advanced semiconductor packaging, and with thermal-management materials where even trace radioactive impurities can compromise chip reliability.”

“Taken together, these results provide a strong technical foundation for pilot-scale optimisation, now underway, and future engagement with semiconductor-sector customers.”