Bezant provided information on encouraging results of Phase 1 metallurgical testing carried out byWardell Armstrong International on a sample from its' 100% owned Kanye manganese exploration project in Botswana. The primary objective of the work was to investigate the amenability of extracting manganese from the Kanye mineralisation by sulphuric acid leaching. Wardell Armstrong International (WAI) was commissioned by Bezant to undertake a programme of metallurgical testing on a sample from the Kanye manganese deposit, Botswana.

The primary objective of the testwork was to investigate the amenability of effectively extracting manganese from the mineralisation by sulphuric acid leaching. A secondary objective was to undertake a small programme of sample characterisation including chemical, XRF and XRD analysis. X-Ray Fluorescence analysis on the whole rock samples was conducted to determine the weight percentage of major rock-forming elements.

The results showed that the sample primarily consisted of silicon dioxide and manganese oxide constituents, with minor phases of iron oxide and aluminium oxide. X-Ray Diffraction analysis on the whole rock sample was conducted to determine the weight percentage of individual mineral phases. The results showed that the sample primarily consisted of quartz, with lesser pyrolusite, goethite and talc.

WAI determined the Kanye composite to have a manganese head grade of 15.48% Mn obtained using an aqua regia digestion with an ICP-OES finish. Six leach tests were conducted on the sample under varying conditions such as grind size, sulphur dioxide addition, and pH at a temperature of 60oC. A benchmark review of similar projects found sulphur dioxide to be an important parameter in the reduction of manganese to become more amenable to sulphuric acid leaching.

The relationship observed demonstrates that sulphur dioxide (SO2) addition has a strong correlation to the overall manganese recovery. Overall manganese recovery ranges from 1.9% to 99.4% for 0.34kg/t to 500kg/t of sulphur dioxide addition for ALT1 and ALT3 respectively. In ALT6, pH was increased from 1.0 to 1.5 to reduce the overall acid consumption over the course of the leach to obtain more economic conditions for processing.

Sulphuric acid consumption was reduced from 246kg/t to 217kg/t resulting in a decrease of overall manganese recovery from 82.6% to 79.2% for ALT5 and ALT6 respectively. Except for ALT1 and ALT2, where the resolution of the leach kinetics could be distorted as a result of poor recoveries, all tests demonstrate fast leach kinetics with relative manganese recoveries after 1 hour of leaching ranging from 84.9% to 90.7% for ALT6 and ALT3 respectively. Sample Characterisation: WAI determined the Kanye composite to have a manganese head grade of 15.48% Mn obtained using an aqua regia digestion with an ICP-OES finish; X-Ray Fluorescence analysis found the major elemental oxide present in the sample is silicon dioxide, with lesser amounts of manganese, iron, and aluminium oxides at 63.83%, 17.94%, 6.02%, and 2.61% respectively.

X-Ray Diffraction analysis found the major mineral phases present were quartz and pyrolusite at 71.4% and 10.4% respectively. This is comparable to the metal composition from XRF analysis. Sulphuric Acid Leach Testwork: Sulphuric acid leaching demonstrated an amenability to extract manganese from the sample into solution.

Manganese recoveries of 99.4% could be achieved at a pH of 1.0 and sulphur dioxide addition of 500kg/t; Sulphur dioxide addition values were found to have a direct correlation to the overall manganese recovery; With the exception of ALT1 and ALT2, the leach kinetics of manganese recovery were shown to be fast, with relative leach rates after 1 hour ranging from 84.9% to 90.7% for ALT6 and ALT3 respectively; Acid consumption values ranged from 27kg/t to 477kg/t for ALT2 and ALT3 respectively; pH was shown to influence the overall manganese recovery with a decrease from 82.6% to 79.2% when pH was increased from 1.0 to 1.5 for ALT5 and ALT6 respectively. Planned Phase 2 Test Work - WAI Recommendations: The primary objective is to continue from the previous phase of acid leach testwork to optimise the leaching parameters for economic processing of a manganese ore, whilst tracking a range of other elements relevant to the economics of battery-grade manganese production. Specifically, WAI recommended the following: Undertake further optimisation leaching testwork to decrease the level of acid consumption over the course of the leach.

This could include variables such as further grind size investigation at elevated recoveries, leach optimisation at elevated pH, increased temperature, and calcination pre-treatment; Track the recovery of other analytes that are likely to have an impact on the downstream purification process circuit of battery-grade manganese sulphate monohydrate production; and Consider maintaining a redox potential with the addition of sulphur dioxide throughout the leaching process at defined intervals, as opposed to a single, substantial addition at the beginning of the leach process.