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Kavango Resources plc Completes Metallurgical Testwork Programme At Hillside Gold Project
Kavango Resources plc, the Southern Africa-focused metals exploration and gold production company, announced the results from a detailed and comprehensive metallurgical testwork programme on ore samples from the Hillside Gold Project ("Hillside"), Zimbabwe. The programme achieved its objective of defining the optimal processing design, processing parameters, and reagent consumption rates for the 50 tonnes-per-day ("tpd") carbon-in-leach ("CIL") gold processing plant at Hillside, and for a future capacity upgrade. Testwork completed on various blend compositions of Nightshift and Bill's Luck ores demonstrated high metallurgical recoveries of gold within standard processing parameters. Very high overall metallurgical recovery of >95% achieved in ideal lab conditions, tested during the optimisation test work. Real-world conditions are expected to deliver in the 90-93% recovery range. The Nightshift sample's gold speciation indicated 100% of the gold was native (non-refractory), whilst speciation of the Bill's Luck sample indicated 91% of the gold was in a free milling (native gold and Electrum) form. Limited coarse gold detected in the samples tested. Gold species were very fine-grained. Very low content of elements that could potentially act as pregnant liquor gold robbers, such as native carbon minerals, and of elements that could potentially lead to high reagent consumption, including copper and zinc. Variability test work indicated that a target grind size of 75 microns was optimal for recovery. Gravity recovery via centrifugal concentrators ranged from 50% to 90%. Gravity gold concentrates can be leached via standard Intensive Leach Reactor ("ILR") technologies with up to 90% recovery after eight hours of leaching time, and 98% recovery after 24 hours of leaching time. Required reagent and energy consumption rates to achieve high recoveries are within normal ranges. The information from the testwork will also prove invaluable for optimising and refining the 50 tonnes-per-day plant once it is operational. Kavango has completed a metallurgical testwork programme in cooperation with Solo Resources ("Solo"), using Maelgwyn Mineral Services ("Maelgwyn"), both based in South Africa. SGS South Africa ("SGS") was subcontracted by Maelgwyn to complete the mineralogical analysis and assessment portion of the scope. SGS is a SANAS-accredited laboratory, and Maelgwyn is an ISO 9001:2015 certified laboratory. A total of ten samples were utilised in the testwork programme. The two main composite blends tested were those deemed to best represent the expected feed material into the two planned processing plants at Hillside: 50 tpd plant - currently under construction - Composite D - 50% Bill's Luck Underground High Grade, 50% Bill's Luck Underground Medium Grade. Upgrade to 250 tpd - Composite C - 70% Nightshift Fresh Rock, 15% Bill's Luck Underground High Grade, 15% Bill's Luck Underground Medium Grade. Other plausible feed blends to either of the above plants that were tested included the following: Composite A- 50% Nightshift Fresh Rock + 50% Nightshift Oxidised Rock, Composite B- 100% Bill's Luck (40 % BL high grade, 40% BL medium grade, 20% BL low grade), Composite E- 50% Nightshift Fresh Rock, 50% Bill's Luck Fresh Rock (50% BL high grade, 50% BL medium grade), Composite F- 100% Bill's Luck (50 % BL low grade, 40% BL medium grade), Composite G- 100% Nightshift Oxidised Rock, Composite H- 100% Nightshift Fresh Rock. The average head grades assayed from each of the composite blends are shown in the table below: Composite A: Au 1 (g/t) 1.08, Au 2 (g/t) 0.99, Au 3 (g/t) 1.09, Au 4 (g/t) 1.05; Composite B: Au 1 (g/t) 4.17, Au 2 (g/t) 3.33, Au 3 (g/t) 2.93, Au 4 (g/t) 3.78, Au average (g/t) 3.55; Composite C: Au 1 (g/t) 3.02, Au 2 (g/t) 2.97, Au 3 (g/t) 3.25, Au 4 (g/t) 3.08; Composite D: Au 1 (g/t) 8.15, Au 2 (g/t) 8.42, Au 3 (g/t) 8.21, Au 4 (g/t) 8.26; Composite E: Au 1 (g/t) 2.79, Au 2 (g/t) 2.63, Au 3 (g/t) 2.96, Au 4 (g/t) 2.79; Composite F: Au 1 (g/t) 2.03, Au 2 (g/t) 2.13, Au 3 (g/t) 2.15, Au 4 (g/t) 2.10; Composite G: Au 1 (g/t) 0.48, Au 2 (g/t) 0.55, Au 3 (g/t) 0.55, Au 4 (g/t) 0.53; Composite H: Au 1 (g/t) 1.75, Au 2 (g/t) 1.82, Au 3 (g/t) 1.71, Au 4 (g/t) 1.76. Mineralogical studies were conducted on Bill's Luck and Nightshift ores. The results are very positive with negligible pregnant liquor robbers present (Carbon), and low concentrations of elements that could lead to high reagent consumption (i.e. Copper, Zinc). The table below shows gold species detected. Gold Mineral Bill's Luck (Fresh) Nightshift (Oxide) Native Gold (Au, Ag) 84.63% 100.00% Calverite (AuTe2) 7.34% Electrum (Au(Ag)) 6.40% Aurostibite (AuSb2) 1.16% Petzite (Ag3AuTe2) 0.48% Total 100.00% 100.00%. The majority of the gold species for both Bill's Luck and Nightshift occur as native gold. The gold species at Nightshift are much finer than at Bill's Luck. The tables below show the liberation characteristics of the gold species: Liberation by Volume % of gold in host minerals Bill's Luck (Fresh) Nightshift (Oxide) Locked (< 30%) 27.5% 99.5% Low Middlings (>=30%, <60%) 9.2% 0.3% High Middlings (>=60%, <90%) 45.3% 0.0% Liberated (>=90%) 18.0% 0.5% Total 100.00% 100.00%. Liberation by Exposure % of gold in host minerals Bill's Luck (Fresh) Nightshift (Oxide) Locked (<10%) 25.5% 98.5% Partially Exposed (10-30%) 0.8% 0.8% Exposed (30-50%) 24.4% 0.2% Exposed (50-80%) 31.3% 0.0% Exposed (>=80%) 18.0% 0.5% Total 100.00% 100.00%. The gold species at Bill's Luck (in Fresh Rock) are more easily liberated than at Nightshift (in oxide rock). Average assayed residue (tailings) grades of 0.14 grammes per tonne ("g/t") and 0.11 g/t gold were recorded for Composites C and D during the kinetic leach tests. These translate to total plant recoveries under ideal laboratory conditions of 97% and 96%, respectively, for Composites C and D. Five Stage GRG Tests using a Falcon centrifugal gravity concentrator were conducted on composites A, C, and D to determine GRG % versus different grind sizes. Three Stage GRG Tests using a Falcon centrifugal gravity concentrator were conducted on composites E, F, G, and H to determine GRG % versus different grind sizes and fluidisation pressures. The results clearly demonstrate the optimal grind size is at P80 = 75 microns for all composites. Under lab conditions, up to 69% of the gold could be recovered via gravity concentration for Composite A, while Composite C achieved 90% gold recovery via gravity concentration. Composite D achieved a gravity recovery of 87%. Up to 90% of the gold could be recovered via gravity concentration for Composites E and F, while Composite C achieved 59% gold recovery via gravity concentration, and Composite H achieved a gravity recovery of 50%. During plant commissioning, fluidisation pressures will be optimised within the ranges tested. ILR tests were performed for future reference, should an elution circuit be chosen to be added to the processing plant(s).