march asx code: bab, aim code: bgl file12 march 2014 asx code: bab, aim code: bgl metallurgical...
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12 March 2014 ASX Code: BAB, AIM Code: BGL
METALLURGICAL TEST‐WORK IDENTIFIES FURTHER POTENTIAL COST REDUCTIONS
Metallurgical test‐work results have demonstrated reduced reagent consumption
Quality of Bullabulling bore water provides options for enhancing leach performance
Potential improvement in gold recovery indicated
Positive implications for cash production costs
Comprehensive follow up test‐work program underway to confirm and quantify benefits, with completion expected by mid‐May
Bullabulling Gold Limited is pleased to report that preliminary metallurgical test‐work undertaken as part on the Bullabulling Gold Project definitive feasibility study (DFS) has identified potential for reducing processing reagent consumption and increasing gold recovery relative to prefeasibility study (PFS) estimates, with positive implications for cash production costs.
The recent test‐work was primarily undertaken to determine if nanofiltration of process water would reduce consumption of lime and cyanide during gold ore processing at Bullabulling. Estimated expenditure on lime and cyanide in the PFS exceeded $30 million per annum1, or $170 per ounce2, providing scope for a significant reduction in costs if consumption was reduced.
Comparative leach tests were carried out on primary and oxidised Bullabulling mineralised samples using raw and nanofiltered water extracted from the existing bore field at Bullabulling. Average consumption of lime during leach tests carried out in filtered water was 64% lower than in raw bore water, with cyanide consumption 26% lower. There was no net change in gold recovery at the PFS specified leach residence time of 24 hours, however extending residence time to 48 hours increased gold recovery in all leach tests to a greater extent than was expected. It is anticipated that upgrading water quality through nanofiltration could be positive for gold recovery during full scale operations as it would enable higher pH levels to be maintained and assist in achieving optimum leach conditions.
Whilst the test‐work results are highly encouraging, it must be noted that they are based on a limited number of tests and more definitive work is required to validate the preliminary results. There is no certainty that forecast reagent consumption will be reduced to the extent indicated.
The Company has now committed to the next phase of metallurgical testing, which will include more extensive, synergistic evaluation of:
Nanofiltration
Pre‐leach gravity concentration
Leach residence time
Optimum leach circuit cyanide concentration and pH levels
Bulk water samples from five separate bores within the Bullabulling bore field (to ensure sample representivity) have been delivered to Eco Technol Pty Ltd in Perth for further nanofiltration
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testing and production of filtered water for the next phase of leach testing. This work is now underway.
A mineralised sample for the complete next phase of the metallurgical program has been sourced from existing drill sample stocks and delivered to Bureau Veritas Minerals Pty Ltd, who will conduct the gravity and leaching test‐work and assess reagent consumption. Preparation of bulk composite samples representative of the proposed mill feed has commenced.
The program is expected to be completed by mid‐May 2014 and should enable key decisions on process flowsheet design to be finalised. Further variability testing on mineralised samples from throughout the deposit will be required to achieve full DFS standards. This phase of the study will require additional diamond drilling to be undertaken to provide the necessary core samples. Drilling is scheduled for the second quarter of 2014.
The Application of Nanofiltration to Gold Processing at Bullabulling
Nanofiltration is a membrane filtration process developed in the 1980s that is generally used for extracting very fine particles and dissolved elements from water. It operates on a similar basis to reverse osmosis (RO), but is less intensive and therefore has a lower implementation cost.
At Bullabulling, in common with most CIL gold plants, it is proposed to add quicklime to the circuit to adjust pH levels to achieve appropriate conditions for gold leaching by cyanide. However magnesium present in the raw process water consumes lime before it addresses pH.
Nanofiltration can be used to extract magnesium from the process water to reduce consumption of lime. Nanofiltration tests carried out on Bullabulling bore water reduced magnesium levels by an average of 93%. In addition to reducing lime consumption, removal of magnesium assists higher pH levels to be achieved and maintained, which is expected to result in reduced cyanide consumption, as indicated by the preliminary leach test results reported above.
Nanofiltration is not commonly used in the Western Australian minerals industry. This may, at least in part, be explained by the fact that many Western Australian gold mines only have access to highly saline water and nanofiltration is generally not effective in hyper‐saline conditions. The Bullabulling bore field has a relatively low salinity level, with total dissolved solids at around 50,000 ppm. The preliminary test work results suggest this may provide Bullabulling with a competitive advantage in relation to the use of nanofiltration to reduce processing costs.
For information, contact:
Brett Lambert Bullabulling Gold Limited Level 2, 55 Carrington Street Nedlands, WA, 6009, Australia Tel: +61 8 9386 4086
Westhouse Securities Limited (UK Broker & Nominated Adviser) Martin Davison / Dominic Palmer‐Tomkinson / Hugo Rubinstein Tel: +44 20 7601 6100
Neil Boom Gresham PR Ltd (UK media) Tel: +44 7866 805 108
John Gardner / Rupert Dearden MAGNUS Investor Relations. Corporate Communication. (Australian Media) Tel: +61 8 6160 4900 [email protected] [email protected]
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Competent Person Statement
The information in this report that relates to the Exploration Results, Mineral Resources or Ore Reserves is based upon information compiled by Mr Trevor Pilcher, who is a full time employee of the Company and is a member of The Australasian Institute of Mining and Metallurgy. Mr Pilcher has sufficient experience relevant to the style of mineralisation and type of deposit under consideration and the activity in which he is undertaking to qualify as a Competent Person under 2012 Edition of the Australasian Code for Reporting Exploration Results, Mineral Resources and Ore Reserves (JORC Code). Mr Pilcher consents to the inclusion in this report of the matters based on his information in the form and context in which it appears. Notes
1. Based on the following prefeasibility study (PFS) assumptions; cyanide cost $2.76/kg, lime cost $0.30/kg, cyanide consumption 0.91kg/t, lime consumption 5.21kg/t and annual throughput 7.5Mt. The Bullabulling PFS was released on 7 February 2013.
2. Based on forecast average gold production of 175,000 ounces per annum. Material assumptions supporting the production forecast were released on 7 March 2014.
3. The information in this report that relates to the Exploration Results, Mineral Resources or Ore Reserves was prepared and first disclosed under the JORC Code 2004. It has not been updated since to comply with the JORC Code 2012 on the basis that the information has not materially changed since it was last reported. All material assumptions and technical parameters underpinning the estimates of mineral resources continue to apply and have not materially changed.
About Bullabulling Gold Limited
Bullabulling Gold Limited is listed on the Australian Securities Exchange (ASX:BAB) and London’s AIM Market (AIM:BGL) and has approximately 344 million shares on issue. The Company’s primary asset is the wholly owned Bullabulling Gold Project, located 60 kilometres west of Kalgoorlie in Western Australia.
The Bullabulling Gold Project hosts JORC compliant Mineral Resources3 of 3.75 million ounces comprising Indicated Resources of 72.4 million tonnes at 0.98 g/t gold (2.28 million ounces) and Inferred Resources of 41.6 million tonnes at 1.11 g/t gold (1.47 million ounces). Exploration has demonstrated strong potential for further expansion of the resource base.
The Bullabulling deposit is amenable to bulk tonnage open pit mining and conventional CIL processing. All resources are situated on granted Mining Leases in close proximity to infrastructure.
The Company is conducting a definitive feasibility study into the development of a large scale, low cost mining operation at Bullabulling which is scheduled for completion in 2014.
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