METALLURGICAL test work at Augur Resources Wonogiri Gold-Copper Project in Central Java suggests that a coarser grind size could result in improved gold recovery while also reducing grinding time and lowering operating costs. The tests were carried out on minus 75 micron to minus 106 micron grind sizes with results were compared to the previous minus 53 micron grind.
Processing of single composite sample ground to minus 75 micron indicates that 43.7% gold recovery can be achieved via gravity concentration using a Falcon concentrator and when combined with intensive cyanide leaching of the gravity tailings, a total of 88.3% gold recovery is possible. Additional testing is in progress on four bulk grinds to confirm gold recoveries via gravity concentration and intensive cyanide leaching of both concentrates and tailing.
Based on results to date the option of a gravity and intensive leach of gravity concentrate and tailings flowsheet appears to be technically viable with very good leaching characteristics for little preg-robbing minerals reporting to the gravity (Falcon) concentrate.
Several processing flow-sheet scenarios are being evaluated including gravity concentrations followed by intensive cyanidation to treat the gravity concentrate. The loaded solution produced from the leach reactor would then be fed to a conventional electro-winning cell bank before being conventionally smelted to produce gold doré bullion. Leaching of the more voluminous gravity tailings would require a larger carbon-in-leach circuit.
General ASTM standard rock quality tests of potential aggregate in the area selected for development of a standalone quarry were completed at PT Geoservices laboratory in Bekasi, West Java. Tests were completed on six bulk rock samples made from drill core composite samples collected from three holes drilled within the proposed quarry area. Results indicate that the rock has the properties required to be highly suitable for a variety of stone aggregate uses including concrete.
It is clear from the earlier market study and related discussions with industry consultants that there is strong demand for high quality aggregate in Java to supply ongoing and planned infrastructure projects as part of an extensive transportation upgrade initiative by the government. The company is evaluating several aggregate production scenarios with interested contractors who would provide quarry development and production management services.
Augur has also completed initial drilling comprising six holes for 781 metres on defined copper and gold targets at Toluludu and Tapadaa prospects at the Gorontalo project. Results indicate that additional drilling is warranted within both areas.