Vimy Resources Limited announced preliminary testwork results on an alternative ion exchange resin for its Mulga Rock Project plant uranium circuit. The Mulga Rock Definitive Feasibility Study and the 2020 DFS Refresh confirmed robust financials and a simple, low-cost uranium mining and recovery process, positioning Vimy as Australia's largest, near-term uranium producer. Following the 2020 DFS Refresh, Vimy has embarked on a number of optimisation studies, including evaluating and improving mining and metallurgical processes at Mulga Rock. Following the metallurgical pilot plant testwork that underpinned the 2018 DFS, Vimy identified a high-capacity strong base anionic resin (Lewatit® TP107, manufactured by Lanxess) as having the capacity to be very effective for uranium recovery from saline sulphuric acid leach liquors. The Australian Nuclear Science and Technology Organisation (ANSTO), through its Minerals Business Unit, has since developed and patented a novel two-stage elution for the Lewatit® TP107 resin, demonstrated at a pilot scale on a different uranium project. Early in 2021, Vimy engaged the services of ANSTO to test the chemical, mechanical and physical properties of the Lewatit® TP107 resin and investigate its suitability for the Mulga Rock process flow sheet. The Lewatit® TP107 resin is a strongly basic, macroporous anionic exchange polyacrylic resin initially developed to support drinking water and groundwater treatment applications. It was designed to offer very high metal takeup, fast kinetics, and good physical and chemical stability, which reduces replacement rates and costs. The testwork by ANSTO, and reported here, aimed to test the suitability of the Lewatit® TP107 resin to the recovery of uranium in the Mulga Rock process plant. The testwork concentrated on the physical and chemical properties to determine whether the new resin could improve uranium recovery and reduce costs. Key outcomes of the testwork showed the following: Preliminary sizing and mechanical testwork indicate that the Lewatit® TP107 resin is equally as suitable to the Resin-In-Pulp (RIP) process as the resin tested in the 2018 DFS; Uranium loading tests showed a step-change in loading efficiency with an increase of approximately three times in uranium loading; Successful elution (stripping) of the loaded resin using ANSTO's two-stage patented process: Steep elution profile, indicating increased extraction of uranium in the leach due to reduced preg-robbing; o Very low residual loading on the resin following elution; High eluate uranium concentration, which might support eliminating the nanofiltration plant from the process flowsheet in a continuous elution configuration; and The deportment of impurities was very low. The results justify moving to the next phase of testwork, which will evaluate performance under the optimum operating conditions determined in the 2018 DFS and opportunities for process optimisation and resulting flowsheet simplification. This will include: Follow-up testwork to demonstrate the benefits of the Lewatit® TP107 resin by testing it in a small scale mini-plant configuration to benchmark against DFS pilot plant results. That testwork will investigate the following: Screening and fouling characteristics of the resin; Leach/RIP and elution properties in a continuous configuration; Potential increase in overall uranium recoveries (each 1% increase in recovery may result in a AUD 1/lb U3O8 decrease in operating cost); Improving recycling of the resins and minimising resin loss; and o Process integration and design: Given the potential for very high uranium concentration in the eluate, it is possible that the nanofiltration circuit, with a capex of AUD 7 million, might not be required in the Mulga Rock process flowsheet. The loading for the Lewatit® TP107 resin was approximately three times that of the 2018 DFS WBA resin at 10g/L Cl (about 2% salt), with a loading of 76 g U3O8/Lwsr compared to the 25g/Lwsr1 assumed in the DFS. At higher salinity and lower uranium concentrations, the relative loading improvement is even more pronounced (almost six-fold at 20 g/L Cl (47 vs 8 g U3O8/Lwsr, see below). This suggests that the Lewatit® TP107 resin could potentially be used in a much more saline environment than the 2018 DFS resin. The loading isotherm for the Lewatit® TP107 was considerably steeper, suggesting that a lower tailings concentrations could be obtained and fewer tanks required in the RIP circuit. Slower loading kinetics for the Lewatit® TP107 are consistent with the much greater loading on the resin. Elution testwork Previous work with the Lewatit® TP107 resin showed that it is difficult to elute by conventional means. ANSTO subsequently developed a novel elution method based on a two-step process: Conversion step: achieved by contacting the resin with a minimal quantity of sodium carbonate to convert the uranyl sulphate complexes loaded on the resin to uranyl carbonate complexes. Elution step: elution with sodium chloride solution to elute the weakly bound uranyl carbonate complex. The elution testwork was carried out at ambient laboratory temperature (21°C). Results: Two-stage elution tests were equally successful, despite the preliminary nature of the testwork: Steep elution profile, nearing completion within 10-bed volumes A peak eluate concentration greater than 20 g/L U3O8 and an average eluent tenor of 7.4 g/Lwsr; Very low residual loading on the resin following elution (<1gLwsr U3O8); Deportment of impurities to the eluate was very low, with average concentrations over the first 10 Bed; Volumes (BV) of elution of < 1-2 mg/L. Results suggest that this resin might be well suited to a continuous style elution (similar to the one retained in the DFS).