King River Resources verifies >4N High Purity Alumina via repeat assays

King River Resources Ltd (ASX:KRR) has completed additional internal and external High Purity Alumina (HPA) purity assay checks to verify the previously reported production of HPA at >4N (99.99%) purity. To help ensure quality control and quality assurance, three sets of assay checks were undertaken on the HPA samples:  Source Certain International (SCI) produced a new HPA Batch (HPA 7) which was assayed by SCI using the Microwave digest ICP-MS and ICP-AES1 method.; SCI completed multiple repeat assays of HPA Batches 2-7 by the Microwave digest ICP-MS and ICP-AES1 method; and An independent laboratory assayed HPA Batches 2-6 by the fusion-X-ray Fluorescence Spectrometry (XRF) and fusion-Laser Ablation (LA) Mass Spectrometry (MS) methods.  HPA Batch 7 Results  SCI produced another 4N purity HPA result from HPA Batch 7 using a new sample of high purity Precursor that was calcined then washed by a simplified process designed to reduce costs. HPA 7 was analysed using the Microwave digest ICP-MS and ICP-AES1 assay method. The 4N purity result was calculated by the addition of all the assayed element impurities that reported above the detection limit then subtracting this result from 100%.  The 4N purity value was 99.9934% containing 66 parts per million of impurities which is below the 100 parts per million impurity threshold for 4N HPA.  The main contaminants in HPA Batch 7 are silicon, potassium, sodium and iron, plus low levels of niobium and chromium which, together with some of the iron, may be the result of contamination from the furnace heating elements.  Repeat assays  SCI completed repeat assays using the Microwave digest ICP-MS and ICP-AES1 method on separate aliquots selected from HPA Batches 2 to 6 and the new HPA 7 batch.  Five to eight analytical duplicates per HPA sample were completed giving a total of 40 analyses. The HPA purity in all the subsamples is ≥4N, with impurities summing to less than 100 parts per million.  Variability in the results is due to differences in the test sample and the analytical precision. The main impurities are silicon, potassium, sodium and iron.  The graph shows the impurities are less than or equal to 100 parts per million and the purity above the 99.99% threshold line for 4N purity HPA. Independent laboratory assays  HPA Batches 2 to 6 were analysed by an independent laboratory using the fusion-XRF and fusion-Laser Ablation assay methods.  The results reported >4N purity in Batches 2 to 5 with Batch 6 under 4N.  Most of the major element impurity levels, determined using the XRF method, were higher especially silicon, but potassium was lower, in the independent check assays when compared with the SCI Microwave ICP-AES results.  In general, the XRF method reports lower accuracy and precision and more variability at these low analyte concentrations than the ICP methods.  The other minor elements assays determined, using the Laser Ablation-MS method, compared very closely with the SCI Microwave digestion ICP-MS results.  A phase analysis on HPA Batch 4 to confirm the crystal structure is still pending due to workloads by the independent consultant.  Pre-feasibility study updates  The company has continued investigations with government agencies and private owners for an appropriate industrial site in the Kwinana area, 30-40 kilometres south of Perth in Western Australia.  The industrial estate is close to a skilled and productive workforce, hosts specialist centres for chemical and resource-based processing, marine engineering and shipbuilding, and has industrial land areas specifically set aside for companies wishing to invest in downstream processing and other heavy or strategic industrial activities, including the Lithium Valley concept plan.  Como Engineers’ Capex and Opex estimates are pending some final modifications of the HPA washing circuit and on completion, the pre-feasibility study documentation will be finalised for release to the market.  Mini pilot plant  KRR has named its HPA refining process the ARC HPA process route, to highlight the aluminium chemical feedstock, the use of only recrystallisation steps in purification, and final calcination.  Work has commenced on the development of a mini-pilot plant to demonstrate the ARC HPA process works at a larger scale for the definitive feasibility study (DFS) and to produce market samples.  The process flowsheet and mass balances have been used to scale the mini-pilot plant and enquiries with vessel vendors are underway.  The 1500°C rotary tube furnace, used for the calcination stage of the process, is currently undergoing checks by the supplier in Australia and is expected to be delivered shortly.  In addition, metallurgical HPA test-work will be ongoing to further refine the ARC HPA process for the DFS with the current focus on further improving the precursor product to simplify the final calcination stage.  Test-work is also ongoing into extracting high purity vanadium and titanium products from the Speewah vanadium deposit suitable as intermediate products for battery and master alloy applications.