Nov 14 2012
Avala Resources Ltd. (TSX VENTURE:AVZ) (the "Company" or "Avala") is pleased to announce an initial summary of ongoing metallurgical testwork on the Bigar Hill, Korkan and Kraku Pester deposits, which form part of the Timok Gold Project (TGP), an emerging sediment-hosted gold belt located in Eastern Serbia.
- Testwork shows that a significant proportion of the TGP mineralization, including the primary material in all three deposits, is free milling, with an average CIL recovery of 61% for the Korkan, Bigar Hill and Kraku Pester sediments.
- Bigar Hill oxidized material returns 95% CIL recovery.
- A conceptual flowsheet involving flotation, pressure oxidation followed by intense leaching of the POX residue, and CIL leaching of the flotation tailings has achieved 77% recovery and overall gold extraction can be improved significantly with optimization of the flotation process, with a target recovery in excess of 80%.
To date, some 315kg of quarter PQ and HQ core, representing 218 meters of drill intersection, have been collected from the Korkan, Bigar Hill and Kraku Pester deposits. Metallurgical samples have been carefully chosen to be representative of the proportion of different lithologies, oxidation state, gold and sulphur grade ranges.
In addition, over 11,800 five-meter mineralized composites have been collected from the three deposits, using the Avala sample pulp library, for a major variability sampling program, to be completed in Q1 2013. The mineralized composites, collected using a notional 0.1g/t cut off grade, will be tested using a bottle roll cyanidation extraction followed by duplicate residue assays, in order to map the inherent 'in situ' recovery, based on a particle size of p80 75 microns, in three dimensions as part of the development of a comprehensive geometallurgical model.
Metallurgical testwork has been designed and carried out by SGS Mineral Services UK in Cornwall, UK and SGS Lakefield (SGS), and by Resource Development Inc (RDI) of Denver, Colorado.
Complete details of testwork carried out and the generation of the conceptual flowsheets are given in Appendix 1.
Based on the results of the work to date, the conceptual flowsheet comprises grinding, flotation, pressure oxidation (POX) of the flotation concentrate, followed by intensive cyanidation of the POX residue, along with carbon-in-leach (CIL) of the flotation tailings.
A diagram summarizing the conceptual flowsheet is available at the following address: http://media3.marketwire.com/docs/avz11113.jpg
RESULTS
Overall gold extraction using the conceptual flowsheet can be projected to be at least 80% as the various component parameters are optimized. Gold extraction of POX material ranged from 87% to 93% with leaching of the flotation tailings returning 50% to 67% recoveries, for overall gold recoveries of 68% to 77%. Overall gold extraction can be improved significantly by optimization of the flotation process. Further testwork to optimize the flowsheet and test alternative methods are planned for 2013.
PLANNED ADDITIONAL METALLURGICAL TESTWORK
An extensive program of additional metallurgical testwork is planned during 2013. Planned activities include the following:
- Bottle roll analysis and residue assaying of the +11,800 five meter composite database.
- Additional pulp resampling to expand the bottle roll composite database.
- Development of 3D geometallurgical models of Bigar Hill, Korkan and Kraku Pester.
- Extensive variability sampling and metallurgical testwork.
- Flotation parameter optimization.
- Determination of the optimal oxidation process, including bacterial leaching testwork.
- Additional studies on optimizing leaching of the flotation tailings and 'run-of-mine' ore.
- Additional mineralogical studies.
- Further refinement of the optimal metallurgical flowsheet.
- Additional comminution studies, including separation of barren sedimentary clasts.
Commenting on the results of the metallurgical testwork, James Crombie, President and CEO of Avala said, "We are extremely pleased with the results of the testwork so far. Further work to optimize this process and additional work on alternative methods such as bacterial leach should further improve the overall recoveries."
QUALIFIED PERSONS
The metallurgical testwork has been managed and reviewed by independent qualified person Dr. Deepak Malhotra SME of Resource Development Inc. Dr. Malhotra of RDI has reviewed and approved the contents of this press release.
The other technical information contained in this press release was prepared and approved by Dr. Julian F. H. Barnes, FAusIMM, MAIG, a director of the Company and special consultant. Dr. Barnes is a 'qualified person' within the meaning of that term under NI 43-101. An updated technical report in compliance with NI 43-101 is being compiled and will be filed on SEDAR within 45 days of this press release.
Source: http://www.avalaresources.com