AERIS RESOURCES LIMITED
Aeris' Executive Chairman,
This will result in a simpler flowsheet for the ore processing plant, enhancing project economics through a smaller physical footprint, lower capital and operating costs and reduced carbon emissions (reduced energy consumption). The bulk concentrate will be processed through an offsite
Background
The Stockman Project Feasibility Study (FS) recommended the investigation of a modified flotation and metals leaching process (Alternative Processing Route). This Alternative Processing Route would replace the conventional selective flotation plant, which would have produced separate export quality copper and zinc concentrates, for metal recovery by smelting. The conventional selective flotation process originally considered in the FS results in modest metal recoveries, requires extensive use of reagents and high-power consumption for fine grinding to liberate the copper and zinc minerals. The highpower consumption and the isolation of the mine would require a diesel or gas power station, with attendant carbon emissions, at a significantly higher cost than grid power. The Alternative Processing route investigation has conceptually tested the use of proven metal treatment technologies: the Jameson cell for improved froth flotation and the Albion Process for metal leaching. The investigation was designed to proof, at a laboratory scale, the improved metal recoveries and lower power and reagent consumption for the ore processing plant, through inclusion of an Alternative Processing route. The investigation included a conceptual engineering design of a smaller, simpler and more sustainable (lower carbon emission) ore flotation processing plant, as well as the remote Albion Process leach plant.
Metallurgical test work The metallurgical test program sought to validate the assumptions of the Alternative Processing route: First selective flotation of the easy-to-liberate copper minerals to a clean export quality copper concentrate. About 40 to 50% of the copper minerals are liberated without fine grinding and will report to the copper concentrate; Second flotation of all zinc and the remaining copper minerals to a bulk concentrate. More of the precious metals should also report to this bulk concentrate; Bulk concentrate is treated in an Albion Process plant by acid leaching to recover the copper and zinc and, Precious metals are recovered from the Albion Process tailings via a cyanidation or similar process. The Albion Process can convert refractory gold and silver minerals to cyanide soluble form
Flotation test results
Flotation tests were completed at the AMML laboratory. Experience from earlier test programs was used to design the test conditions. The ore samples were provided from the 20233 diamond drilling program, which provided new drill core for metallurgy testing purposes. This drill core has been carefully managed and stored in refrigeration to reduce rate of oxidation aging. The modified conceptual flotation flowsheet produces copper concentrate first and then bulk concentrate. The flotation regime did not require optimisation since the previous results were already encouraging when using known reagents and conditions. This supports the concept of a simple, easy-to-run flotation plant with built-in flexibility. The modified conceptual flotation flowsheet test results show a significant step-up in metal recovery compared to the original selective copper and zinc flotation flowsheet.
Full leach test results
The bulk concentrate was ground to a P80 size 12-microm. The oxidative leach treatment returned zinc extraction of 99.9%, copper of 98.5% and sulphide oxidation of 91% after 72 hrs (under Acid
Albion Process leach plant
The engineering study has recommended conceptual level flowsheets, equipment sizes and reagent consumption rates for the Albion Process plant. The fast kinetics of the leaching of the Stockman bulk concentrate allows for a modest size plant. Further plant options engineering including site layout, general arrangement and cost estimates require more work before public reporting. The final selection of the most likely intermediate products for copper and zinc metal will influence the plant design including further product refinement, as required. From a plant location perspective, the concept is for the Albion plant to be located remote from the mine site but within reasonable trucking distance. There are several locations in the region being considered that are adjacent to major electricity grids, have excellent logistics access and available industrial land.
Contact:
Tel: +61 7 3034 6200
Email: investorrelations@aerisresources.com.au
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