공시 • Jun 04
Kin Mining NL Reports Strong Results from Metallurgical Testwork on Cardinia's Sulphide Ores
Kin Mining NL reported positive metallurgical testwork results from sulphide ores from the Cardinia Hill, Helens and Lewis deposits, all located within the Cardinia area of its 100%- owned 1.275Moz Cardinia Gold Project (CGP) located near Leonora in Western Australia. The metallurgical testwork program was designed to confirm the most cost-effective processing route for each ore type confirmed within the large, rapidly developing Western and Eastern Corridor mineralised complex which make up the Cardinia area. Mineralisation discovered at Cardinia extends over an area of approximately 1km by 5km on the western and eastern side of Cardinia. Cardinia contains a number of exciting development prospects, including Cardinia Hill, Helens, Bruno, Lewis, Fiona, Rangoon and East Lynne, which collectively contain in excess of 650koz of Mineral Resources. Where sulphide ore has been drilled below the oxidation depth, common features of all the mineralized locations have been noted in geological logging and multi-element assays. These features include strong associations between gold mineralisation and pyrite, moderate levels of silver mineralisation and anomalous copper, lead, molybdenum, tellurium and zinc. These pathfinder minerals are also expected to report to flotation concentrates as they are associated with the sulphide style of mineralisation dominant at Cardinia. Metallurgical testwork programs were conducted and supervised by Independent Metallurgical Operations during 2020, 2021 and early 2022 on samples provided from exploration drilling programs and special metallurgical drilling programs. All samples supplied were either whole or half PQ and HQ sized diamond drill core. The scope of this work included: Sample Characterisation: Comminution test work, Head Assay; Gravity Concentration; Whole of Ore cyanide leaching; Sulphide Flotation; Flotation product re-grinding and leaching; Variability testwork. Master Composite samples were generated from weighted averages of variability composites which covered the range of depths and locations within each ore body and a range of head grades of gold and sulphide mineralisation. Mineralisation in general is characterised by zones with quartz carbonate veining, fine pyrite mineralisation and sericite alteration. IMO ran a series of variability tests on five composite samples (IC3 to IC8) created from drill cores within the Cardinia Hill Mineral Resource, with individual composite assay head grades ranging from 1.37g/t Au to 8.55g/t Au. Conventional grinding, gravity and cyanide leaching tests under optimal conditions were undertaken for each Variable Composite, which yielded gravity recoveries ranging from 4.3% to 46.7% and overall recoveries with a 48-hour leach residence time of between 81.2% and 95.7%. Weighted average. Residue Grades varied between 0.20g/t Au and 0.65g/t Au after 48-hour leach to average 0.35g/t Au for a conventional grind, gravity and leach process. Cyanide and Lime consumptions were low. To determine flotation and leaching comparison metrics, IMO ran flotation tests on all five Variability Mass Recovery to concentrate varied between 7.2% and 17.1% to averaged 10.9%. Rougher concentrate recovery varied between 71.7% and 94.5% for gold and 89.6% to 95.5% for sulphur. Rougher concentrate averaged 26.2 g/t gold and 23% sulphur. The weighted average of the Variability Composites using flotation, re-grinding of the flotation concentrate and leaching with elevated levels of cyanide resulted in 97.6% recovery of gold from the Rougher concentrate. Standard 48-hour leaching was undertaken on the Rougher Tails resulting in 88.0% recovery for this portion. These tests included flotation optimization tests on Lewis and Helens composite sulphide ores derived from HQ sized core taken from exploration drill programs. Two composite samples for Helens and three composite samples for Lewis were created and were ground to either 150um or 106m and subject to flotation to produce Rougher concentrate and Flotation Tails. Rougher concentrate was reground to approximately 10m and leached with high concentrations of cyanide, while the Rougher Tail was leached in a conventional 48hr test. Standard Grind-Gravity-Leach tests were also undertaken on these samples to allow comparison. Results show gold recoveries of between 83.1% and 90.8% for Lewis sulphide ores and 90.2% and 91.7% for Helens sulphide ores from the Grind-Flotation-Regrind-Leach process. The Grind-Flotation-Regrind-Leach process resulted in recovery improvement between -0.3% and 12.4% for individual Lewis composites and between 9.3% and 12.6% improvement for Helens composites. The Sighter testwork favoured coarser primary grind and coarser re-grind, resulting in improved overall recovery, with these parameters considered the optimal conditions for future testwork. A number of metallurgical testwork programs were undertaken at Cardinia up until 2019, including the completion of the 2019 Pre-Feasibility Study which showed high metallurgical recoveries generally based on oxide and transitional ore samples available up until that point in time. Optimisation work by IMO showed conventional 150m grind, gravity and 48-hour leaching resulting in, on average, 94.5% recovery for Oxide and Transitional ore types across Cardinia. Test work at that time also showed generally lower metallurgical recovery for fresh ores associated with sulphide mineralisation. Metallurgical recovery of Variability Composites showed recoveries of between 68.7% and 91.1% for Helen's sulphide ores and between 76.6% and 91.1% for Lewis sulphide ores using the conventional grind-gravity-leach process. Weighted average recovery for Fresh sulphide ores from Cardinia averaged 81.5%. When applied as modifying factors to mining and processing production estimates during the 2019 PFS, these results significantly reduced the proportion of fresh sulphide ore able to be economically extracted and reduced pit design depth, ore supply and estimated economic return in the 2019 PFS. Flotation, Rougher concentrate regrinding and leaching under optimal conditions has shown significant improvement in sulphide ore metallurgical recovery, increasing recoveries by up to 12.4% at Lewis, 12.6% at Helens and 6.3% at Cardinia Hill on samples tested to date. These results indicate that coarse Primary Grind, Rougher Flotation and regrinding of concentrates prior to leaching is likely to be included in the flow sheet for treatment of sulphide ores from Cardinia. Metallurgical recovery is likely to be approximately 97% for Cardinia Hill sulphide ores based on optimal conditions testwork, 91% for Helens and 87% for Lewis sulphide ore based on Sighter testwork completed to date.