The Asia Miner

OCT-DEC 2015

The ASIA Miner - Reporting Important Issues to Mining Companies in the Asia Pacific Region

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October-December 2015 | ASIA Miner | 43 Australia Gold REMOVAL of overburden at Havilah Resources Portia Gold Proj- ect in South Australia has been expanding with contracting part- ner Consolidated Mining & Civil (CMC) moving a record amount in July. This has been made possible by steady expansion of CMC's mining capacity along with high equipment availability. Work at Portia began on March 30 and by the end of the June quarter a total of about 1.3 million cubic metres of overburden had been moved. Rates have progressively increased and in July 549,000 cubic metres was removed. At start-up CMC's feet comprised one 250-tonne Hitachi ex- cavator and fve 100-tonne dump trucks operating on a 10 day on-fve day off roster with one crew. A month later there were two feets comprising two 250-tonne Hitachi excavators and 10 x 100-tonne dump trucks operating on a 10 day on-fve day off roster with two crews. CMC has acquired a Maptek Sentry monitoring system, which utilizes a long range I-Site scanner and dedicated soft- ware that when permanently set up overlooking the open pit, can detect and analyse the smallest of movements in the walls of the pit. By the end of July there were two mining feets comprising two 250-tonne Hitachi excavators and 10 x 100-tonne dump trucks operating on a 10 day on-fve day off roster with three crews. This allows the equipment to operate at full capacity 12 hours a day and seven days a week. In addition CMC has em- ployed a 120-tonne Hitachi excavator, two Cat 637 scrapers, two Cat D10T dozers and three water trucks plus support equipment. There are about 50 people in the mine camp with the bus in- bus out transport of personnel from Broken Hill running smoothly and minimizing traffc on local roads. Havilah has maintained responsibility for dewatering the open pit. Drawdown of saline groundwater is materially greater than indicated by groundwater modelling, with fewer pumps in action. This means that continuously maintaining the groundwater level below the advancing open pit foor level should be achievable, especially with additional pumping capacity being available. The re-injection of this water via the managed aquifer recharge sys- tem is functioning according to plan and is accepting all water surplus to operational requirements. Havilah continues to assemble and refurbish the main compo- nents of the gold processing plant. A project manager has been appointed to oversee the task with the view to having the plant on site early in 2016. WITH fnal shipments of underground copper, zinc and lead from KBL Mining's Mineral Hill project in the Central West of New South Wales made in late August, the plant has started processing ore from the Pearse open cut mine. Head grades from Pearse are av- eraging between 6 and 7 grams/tonne gold and 40 to 70 grams/ tonne silver. A plus 50 grams/tonne concentrate will be produced and regularly shipped overseas. In early September the company said stripping of Pearse open cut over the previous 10 weeks had been a feat for management. It said when the project began 14 weeks earlier there was signifcant preparation to make and much overburden to be moved. "More than 600,000 tonnes of waste has been moved and we have hit the top of the sulphide ore body, with more than 8000 tonnes of ore on the plant stockpiles and with the next exposed bench in the pit providing at least a further 30,000 tonnes of ore. The mill will be kept full at all times." Initial indications were that Pearse ore being fed through the Mineral Hill process was performing in line with recent optimization test work. KBL said that upgrades to the existing fotation circuit to allow multi-element processing were nearing completion in early Septem- ber. However, to further enhance gold processing throughput, new Outotec OK16 cells were being installed and commissioned. The expansion of the fotation plant will double the ore residence time of the processing facility and bring a measure of improved effciency. As such, all fotation cells will be dedicated to the pro- cessing of gold and silver ore during the Pearse open cut stage. When KBL returns to processing base metals, the three dedi- cated fotation circuits within the plant will allow for greater fexibility while processing copper/gold, lead and zinc rich ore. With underground activities KBL has reduced the mine contrac- tor to 120 metres a month of capital development opening up the down dip extent of the Southern Ore Zone and additional diamond drilling platforms. In early September development on the decline has reached the 990 level, which was the deepest mined elevation at Mineral Hill to that time. KBL said costs associated with underground mining would reduce by 60% from September as there was no require- ment for production from underground, allowing a reduction of feet and manning. "This development secures the longer term produc- tion profle for Mineral Hill." KBL starts processing Pearse ore Removal of overburden by contracting partner CMC is continuing at Havilah Resources' Portia Gold Project in South Australia, near the border with New South Wales. Record overburden removal at Portia

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