Haranga Resources Limited (ASX:HAR) Industry Comparable Uranium Extraction Achieved With Acid Reduction

(MENAFN- ABN Newswire)

Haranga Resources Limited (ASX:HAR) (FRA:65E0) is pleased to announce the results of an initial sighter leach test program conducted on drill core from the Saraya Uranium Deposit, undertaken by SGS Lakefield (Canada) and supervised by Independent Metallurgical Operations (IMO) in a program of ore characterisation, which commenced in March 2024.
Managing Director, Mr. Peter Batten, commented: "These further results from the ore characterisation testwork are very positive. The initial, aggressive, testwork had already proven that the uranium mineralisation within the Company's Saraya deposit1 (12.45Mt @ 587ppm eU3O8 for 16.1 Mlbs U3O8, Inferred) was leachable. This next round of tests was undertaken to determine if the leach rates at industry standard concentrations and conditions were consistent with existing uranium operations. Uranium recoveries are in line with industry standards from both acid and alkaline routes and provide further scope to optimise extractions using both routes and determine which method is likely to provide optimum project economics.
Both low acid and alkaline leach recoveries were 84%, similar to other uranium late stage development projects and operations and gives Haranga two options to consider when we approach any feasibility studies for the Saraya Uranium Deposit".
Background Metallurgical Testwork
As part of the preparation for a Maiden Resource Estimate, Haranga completed 22 diamond core drill holes at Saraya to confirm the validity of the 65,000m drill hole database that existed at Saraya from previous explorers (Cogema and Areva). The results from this drilling confirmed the presence and tenor of the uranium mineralisation at Saraya. This resource estimate was classified as 100% Inferred due, in part, to the lack of leach tests proving the uranium in the Saraya deposit could be successfully extracted.
Given there had been no previous metallurgical testwork for Saraya, Perth based specialist metallurgical services group - Independent Metallurgical Operations Pty Ltd (IMO) were engaged by Haranga to conduct first pass sighter leach test work with the aim of determining first pass uranium recoveries from a composite sample which represented the uranium grade and mineralogy from the resource estimate. Metallurgical testwork was conducted at SGS Lakefield (SGS) in Canada under IMO's guidance.
Prior to conducting the testwork, IMO conducted a literature review to determine suitable testwork conditions to confirm first pass extractions and what industry established methods would be suitable for leaching of the Saraya material.
Commercial plant acid extractions ranged from 85-90% with current commercial alkaline extractions at approximately 90%.
Testwork Sample
The metallurgical sample has been composited from a number of holes at varying depths to closely represent the results of the Mineral Resource Estimate1 ("MRE") for Saraya.
To compile the sample Haranga relied on existing core from 22 diamond core holes completed by Haranga in 2022 and previously reported in ASX release "Drilling Results Confirm Wide Shallow High Grade Uranium" released on February 28 2023.
The samples were selected from varying locations and depths to realistically represent the mineralised episyenite at Saraya. In all, 243 samples contributed to the bulk sample and these are listed in Appendix 1. Approximately 150 gms was subsampled from each drill core sample and samples were selected to obtain a weighted average grade close to the MRE1 grade of 587 ppm eU3O8.
The metallurgical testwork was conducted on a subset of this composite. The subset had a calculated head grade of 672 ppm U3O8, the SGS Laboratory assayed head grade of the composite was 570 ppm U3O8 and the calculated head grades from the acid leach and alkaline leach tests averaged 544 ppm U3O8, both results similar to the estimated Mineral Resource Grade of 587 ppm eU3O8.
Acid Leach Test
The initial acid leach test3 was conducted at an excess sulphuric addition rate (681 kg/t) and elevated temperature (95oC). This test achieved >96% uranium oxide extraction, exceeding other uranium operations.
The final leached solids grade was below the ICP U3O8 detection limit of 24 ppm indicating almost complete extraction with acid.
Two further acid leach tests were conducted at reduced acid consumptions and then reduced acid consumption and reduced temperature.
The test with reduced acid consumption achieved a uranium extraction of 84% though showed that 90% could have been potentially achieved with additional retention time given the leach rate hadn't plateaued as shown below. The acid addition rate significantly dropped to 224 kg/t in this test as well.
The low acid and ambient temperature test uranium extraction was lower than commercial acid uranium extractions showing that some temperature is required to achieve a commercially acceptable extraction. Heated acid leaching is common in commercial operations.
IMO further recommend conducting beneficiation testwork to determine if acid consuming carbonate minerals can be removed to further reduce acid addition rates whilst still maintaining uranium extraction rates. Further testwork at increased reaction times and progressively reducing temperature is also recommended to determine minimum temperature required to achieved industry standard uranium extractions.
Alkaline Leach Test
The alkaline leach test conducted at elevated temperature achieved a similar uranium extraction (84%) to the low acid test. Leach kinetics were lower with extracted uranium oxide values still increasing in the 24 hour sub-sample. Further optimisation testwork is likely to increase alkaline leach uranium extractions by either decreasing the grind size or varying reagent and leach conditions.
Haranga considers this an excellent outcome from a single test conducted at unoptimised conditions.
Recommendations
Given the similar uranium recoveries from both the alkaline and reduced acid addition routes, IMO recommends conducting further optimisation testwork on both these routes to confirm which leach route will provide optimum uranium recoveries and reduced operating cost to deliver an optimum economic outcome for the project.
Further work may include a detailed mineralogical investigation to determine uranium mineral and liberation properties, particularly association with carbonate minerals and liberation size.
The aim being to determine if high acid consuming carbonate minerals can be separated from the uranium minerals by most likely flotation, though based on the outcome of the mineralogical assessment, other techniques may also be deemed suitable to trial via testwork.
Fieldwork
Fieldwork is continuing in Senegal following the completion of the RC drilling programme in March 2024. Termite Mound Sampling (TMS) is continuing, both regional and infill. Auger drilling is further testing anomalous TMS results reported for Diobi, Mandankoly and Sanela and will proceed to Saraya South, Saraya East and Diobi East.
*To view tables and figures, please visit:
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