Finders reports Indonesian mining activities
Wednesday, October 24 2007 - 12:02 AM WIB
The following is an excerpt taken from Australian firm Finders Resources Ltd quarterly report released on Wednesday
1. Wetar Copper Project,
Finders Resources Limited ~72% and earning through expenditure
Leach Test Work During the period, the Company received encouraging results from laboratory scale test work being undertaken at HRL in At HRL, using non-proprietary bacteria, two amenability tests were run over a 40 day period to assess copper recoveries at elevated (50°C) temperatures. Copper recoveries of 83% and 67% were obtained from Kali Kuning and Lerokis samples respectively. Two additional 2m column tests at elevated (45°C) temperatures have now been running for 11 weeks with approximately 60% and 75% copper recovery. Copper is still leaching into solution and the tests will continue to run for a number weeks. The copper recoveries from the high temperature columns occur at a faster rate than previous leach tests undertaken at room temperature, e.g. for comparison an earlier 2m column using Kali Kuning material had ~40% Cu recovery after 11 weeks. Tests to assess the permeability characteristics of the columns have been taken at different crush sizes and flow rates. The columns perform exceptionally well with little washing of fine material and remain stable at over 300 times the normal irrigation rates. Tests at Ammtec are underway with a series of 1m columns and two of approximately 3m in height to assess the performance of BioheapTM proprietary bacteria. BioheapTM have reported 30-40% Zn recovery in solutions thus far which indicates that sphalerite is leaching preferentially. This is not considered unusual, and copper leaching is expected to accelerate when zinc leaching approaches completion. After 50 days the most advanced columns are those with Kali Kuning material crushed at 6.5mm and 12mm sizes, these show approximately 30-35% Cu recovery at this stage. In each of the columns, the iron leaching rate continued to be very slow, indicating preferential leaching of copper minerals and not pyrite. Trial Heaps and Pilot Plant The Company has completed preliminary cost estimates for the pilot plant phase of the project and expects to complete detailed design of vendor specific components of the SX-EW plant in order to place orders for within the next month. The initial cost estimate of approximately US$6.25m provides for the construction of test heaps and associated infrastructure to permit the installation of a pilot plant with 5t/day Cu cathode production capacity. The main elements of the estimate which is based on indicative quotes and current material prices in is as follows:- US $m Capital Equipment 3.22 Infrastructure 1.09 EPCM & Owners costs 1.25 Contingency 0.69 Total 6.25 The design allows for the trial processing of up to 100,000 tonnes of ore from the Kali Kuning pit. The initial phase of approximately 66,000 tonnes will target run of the mine average grade material to optimise copper recovery using three main parameters, varying crush size, heap height and heap temperature. Once optimized there is flexibility to confirm the optimal parameters with higher grade feed. The pilot plant is expected to run for approximately 12-18 months after which the Company will decide whether to use the equipment in the full scale operation or transfer the plant to the zinc rich Lerokis deposit where further test work of a similar tonnage would focus on optimising the zinc recovery circuit. Feasibility Study Much of the process design work being undertaken for the pilot study is directly relevant to the design of the feasibility study. In addition, preliminary designs for the commercial scale leach pads were completed by SRK Consultants during the quarter and a further six SPT holes and three geotechnical holes completed as part of the geotechnical study. Topographic surveys have now also been completed of the entire project area. Draft environmental impact studies are underway which have also included a site visit by ERM to assist with social and community empowerment programs. The Company has completed the first phase of exploration in the tenements on the southern coast of
Pantai Merah Prospect Within the Exploration KP surrounding the Pantai Merah prospect, detailed stream mapping, float and outcrop sampling and stream geochemistry has been completed over an area of 1,500 hectares This work has successfully identified a tuff sequence with barite mineralisation which appears to be a similar stratigraphic unit to that observed adjacent to the goldcopper mineralisation at the Kali Kuning deposit. This unit can be traced for 2km north of the Pantai Merah prospect providing a greatly enlarged target area which is characterised by a thin cover sequence (estimated to be a maximum of 50m thick) and strong stream geochemistry. Within the expanded mineralised district, float assays from baritic rocks are frequently greater than 1 g/t Au and reach a maximum of 16 g/t Au. Grids are currently being prepared with view to conducting electromagnetic (EM) surveys. EM surveys are designed to explore for sulphide conductors, which in the context of the stratigraphy on Wetar, would help explore for intact gold-copper systems in the Pantai Merah district, similar to those at Kali Kuning and Lerokis. Regional Exploration Regional stream sediment and float sampling has been completed within a 20,000 hectare area covering the General Survey tenements surrounding the known Bati Duri (J91) and Ilwaki (W6) prospects. Both these prospects have had previous scout drilling with significant gold, silver and copper intersects. Four new areas have been identified for more advanced exploration: • Upper Arnau: 2.5km NE of Batu Duri with strong stream geochemistry and float recording assays of 4.3 g/t Au and 140 g/t Ag • Lawair: Strong steam geochemistry and baritic rock floats with assays of up to 8 g/t Au, also significant base metal anomalism with float assaying up to 0.3% Cu and 1.25% Zn • Lasi: Strong geochemistry in a drainage 1km east of the Ilwaki prospect. • Dirkuun: Similar geochemical signature to the known prospects. Both the
2.
Geophysical Surveys To better define structural controls for the vein systems a program of approximately 15 sq. km of detailed (50m x10m) ground magnetics has been implemented, of which about 7.5 sq. km or 150 line km has been completed to date. Preliminary results show a good correlation between known structures and zones of demagnetization. Soils and Channel Sampling A major program of auger soil geochemistry has been implemented to assist in ranking IP geophysical targets, supported by channel sampling of available outcrops and local miner workings. To date 1330 composite soil samples and 600 channel samples have been collected, with assays currently received for about 60% of the total samples. This preliminary data shows strong soil anomalies associated with the Way Umpu, Kencur, Belida and Jambi extended and Cugah targets, supported by significant clusters of channel sample results in the 1 to 10 g/t Au range Drilling No drilling activities were undertaken during the quarter, awaiting mobilization of a new track mounted multipurpose drilling rig from . This rig is now in customs in The planned drilling program for the 4th quarter includes 5,000m of reverse circulation drilling for resource definition at the Jambi oxide deposit, plus an additional 2,000m of reverse circulation drilling as initial follow up of geophysical/geochemical targets on the Way Umpu, Kencur, Belida and Cugah prospects. Tambang Metallurgy A report outlining the results of the first phase of metallurgical results from the Tambang deposit has been received from G & T Metallurgical Services, . The G&T report assessed the preliminary flotation performance of two Tambang polymetallic sulphide composites prepared from drill core intervals from 3 drill holes. The two composites represent silver-rich (Mo1) and zinc-rich (Mo2) samples of the Tambang deposit. Target products were a bulk silver-lead cleaner concentrate and separate zinc cleaner concentrate. A range of metal recoveries were observed from the test work. In rougher test work, 70-80% of the silver reported to a rougher bulk concentrate and 60-80% of the zinc reported to the rougher zinc concentrates. In the cleaner circuit tests, between 60-70% of the silver in both composites was recovered into a low quality bulk concentrate with high copper and low lead grades; these concentrates assayed about 2500 g/t Ag for the M01 composite and 4000 g/t Ag for the M02 composite. The zinc circuit produced a cleaner concentrate that recovered between 70-75% of the zinc. The concentrate produced from M01 and M02 assayed about 50 and 60 percent zinc respectively. Elevated levels of arsenic, antimony, cadmium and bismuth in these concentrates could affect their saleablility. In summary, a two-product flotation flowsheet for the Tambang material produces: • a low quality bulk concentrate with significant silver grades as a result of the presence of copper sulphides and relatively poor sulphide liberation characteristics at the test grind size (P80/95μm). • A moderate grade zinc concentrate with elevated silver, antimony, arsenic and cadmium. A significant program of additional test work and flowsheet development work is required in order to confirm whether three separate marketable concentrates can be produced for a three-product flotation flowsheet. This program would include a copper-lead separation stage, individual copper, lead and zinc flotation stages and finer grinding. The next stage of work at Tambang will also include a definitive mineralogical evaluation of the silver mineralogy and an assessment of alternative processes available to win the silver from the bulk concentrate. (end of edited excerpt)