Asiamet Resources has received positive results from a metallurgical testwork program conducted at the BKM deposit of the KSK project in Indonesia. Samples for the test were obtained from a series of holes drilled as part of a 122-hole resource evaluation drilling program completed as part of the BKM feasibility study.
A key element of the metallurgical test work is the column leach program where representative composites of the various mineralised material types are stacked and percolated with extractive solution for up to 270 days. The results emanating from this work are a key component in the design of the proposed heap leaching, solvent extraction and electro-winning facilities.
Asiamet says results from this metallurgical test work have been very positive to date, and the columns are continuing to leach as anticipated.
The Asiamet team together with consultants Graeme Miller of Miller Metallurgical Services and Duncan Hackman of Hackman & Associates has designed the testing program.
Drill core from metallurgy drill holes was shipped to CORE Laboratories in Brisbane, Australia under the direction of Asiamet’s vice president of exploration Stephen Hughes.
Composites for testing were prepared based on material types and grade, the mining schedule as proposed in the preliminary economic assessment (PEA) and the copper mineralogy and zonation as defined by Asiamet geologists.
Selected drill intercepts correspond to material types that would nominally be mined in the annual mine schedule from years 1 through 8, as defined in the PEA. This resulted in the preparation of six separate drill core composite samples by CORE.
Highlights of the program include:
• A total of 20 columns are actively leaching, comprising 12 short and 8 long columns, with two crush size fractions being tested for each composite sample ie 12.5mm and 19mm.
• Short (2-metre) and Long (6-metre) column leach tests have been operating for approximately 100 days of planned 180 day and 270 day programs respectively.
• Based on the leachable copper head grade assays received to date:
Short columns - leachable copper recoveries for the 12.5mm size fraction have exceeded 87%, and recoveries for the 19mm size fraction have exceeded 75% in some composites.
Long columns - leachable copper recoveries for 12.5mm size fraction have exceeded 72%, and leachable copper recoveries for the 19mm size fraction have exceeded 73% in some composites.
• Positive results from the test work have supported the initiation of additional metallurgical program activities.
The short column tests are expected to be finalised in July and the long column tests in October, with the metallurgical data and conclusions progressively incorporated into the ongoing BKM feasibility study.
This test work forms the basis upon which the proposed leaching, solvent extraction and electro-winning facilities will be designed.
The positive results achieved to date are supporting additional activities including refined diagnostic assay procedures, optical mineralogy assessments, and hydrodynamic testing. These elements have been initiated in the past month.
The leach column test work will continue to be advanced in the coming months, with completion of these activities anticipated in Q3 and Q4. Once interpretation of the results is complete, the Asiamet team will be able to confirm the metallurgical performance of the BKM ore and update the project plans and metrics as appropriate.
Meantime, recent drilling has confirmed further extensions to BKM mineralisation both along strike and at depth.
Chalcocite-covellite copper mineralisation was intersected 50 metres south of the PEA open pit design and thick intervals of moderate to high-grade copper mineralisation extending more than 100 metres below the base of the conceptual open pit design, as proposed in the PEA were intersected.
Resource infill drilling results have confirmed a very robust resource with excellent continuity. As a result, it is expected that a large proportion of the current BKM resource will be upgraded to the higher confidence measured and indicated mineral resource categories when the new resource statement is completed. This will then feed into the mining engineering studies and the reporting of initial ore reserves for BKM.
Asiamet’s CEO Peter Bird said, “The BKM resource upgrade and infill drilling has been completed on time at the end of April 2017 as part of the feasibility study plan.
“Results have confirmed the continuity of mineralisation within the deposit has more than verified that which was assumed in the PEA.
“We are very comfortable with the original PEA assumptions and the recent extensions to mineralisation outside the previously defined envelope encourage us from the perspective of having the ability to grow our resource base over time. The immediate task now is to incorporate all the assay results into an updated resource model for use in the mine design and engineering work, following which an initial mineral reserve can be reported.”