TORONTO, ONTARIO--(Marketwire - April 12, 2012) - Kilo Goldmines Ltd. ("Kilo" or the "Company") (TSX VENTURE:KGL)(FRANKFURT:02K) is pleased to announce encouraging results from preliminary metallurgical test work carried out by Wardell Armstrong, UK, on diamond drill core from the Company's Adumbi Gold deposit, Somituri Project, in north-eastern Democratic Republic of Congo ("DRC").
- 94.2% gold recovery in oxide
- 96.2% gold recovery in sulphide
- 10.5 kWh/t Bond Mill Working indice for composite oxide - below expectation
- 11.3 kWh/t Bond Mill Working indice for composite sulphide - below expectation
Gold recoveries for three oxide composite samples ranged from 92.2 to 94.3% by gravity concentration followed by cyanide leach of the gravity tails. The gold recovery for one sulphide composite sample, which originated at depth from a minor lithological formation, was 42.9%, while two other composite samples returned gold recoveries of 92.5% and 96.2%. Further testing will be undertaken to optimize overall recoveries.
Commenting on these preliminary metallurgical test results, Alex van Hoeken, President and CEO of Kilo stated; "The preliminary test work is very encouraging and indicative that in excess of 90% of the gold in the oxide appears recoverable by the simple process of gravity and cyanide leaching of gravity concentration tails. Given that the recent Inferred Mineral Resource estimate concluded about 600,000 ounces of gold in oxide, most of which is contained within Adumbi Mountain and mineable by open-pit with a very low stripping ratio, the anticipated ease of gold recovery is expected to bode well for the project economics.
In addition, the gold recoveries in excess of 90% for two of the three sulphide samples are most encouraging in that the majority of the sulphide mineralization may also be amenable to gravity and cyanide leaching of gravity concentration tails, in particular when the third sulphide sample is referenced to its host lithology that represents less than 4% of the gold bearing rock types identified in the Adumbi Gold Deposit. Furthermore, the lower than expected Bond Mill Working Indices should have a favourable impact on the power and infrastructure requirements for the project."
Details of the gold recoveries are presented in Table 1.
|Table 1. Wardell Armstrong gold recoveries from oxide and sulphide composite samples.|
|Gravity Concentration followed by Cyanide Leach||Cyanide Leach|
|Gravity Concentrate||Cyanide Leach of
Gravity Concentrate Tails
Gold and Silver Recovery
|Gold & Silver Recovery||Recovered|
|Oxide 3 & 4||32.8||14.0||88.4||98.3||92.2||90.0||81.3|
|Note:||the gravity concentrates were analyzed, but not leached.|
In regard to Sulphide Sample 1, the following is considered noteworthy:
The Adumbi Gold Deposit database consists of a total of 11,659.51 lineal metres of drilling, trenching and adit data. Of this, some 1,861.25 lineal metres returned gold values equal to or greater than 0.30 g/t. The lithology comprising Sulphide Sample 1, which was taken from a maximum vertical depth of 275 m, consists of a very hard, silca replaced unit, currently of unknown chemical characteristics or protolith, however it typically contains up to about 8% sulphides, predominantly, field identified, pyrite. Of the 1,861.25 lineal metres the Sulphide Sample 1 unit represents only 74.85 metres or 3.866%. Hence, the preliminary conclusion is that Sulphide Sample 1, which returned preliminary test work results exhibiting relatively low gold recovery characteristics, represents less than 4% of the rock with 0.30 g/t gold, or higher, and as such is not presently considered to have a significant bearing on the global gold recovery by methods tested from the Adumbi Gold Deposit.
Summary of Metallurgical Test Work:
Kilo submitted samples of one quarter of NQ size diamond drill core from seven drill holes for preliminary metallurgical testing. The four oxide samples cover a strike length of 480 metres and the three sulphide samples were selected over a strike length of 560 metres and to a maximum vertical depth of 275 metres (Sulphide Sample 1) below surface.
Wardell Armstrong prepared composite samples and carried out the following test work:
- Details of the composite samples are listed in Table 2.
- Cyanide bottle roll tests on coarse grinds of 20 mm, 15 mm and 12.5 mm; all returned gold recoveries in excess of 72%; the maximum was 88%.
- Two stage gravity separation on grinds of 500 and 100 micron followed by a direct cyanide leach of the gravity tails.
- Run of mine ("RoM") milling on a 75 micron grind followed by direct cyanidation; 30% of the gold contained in the RoM material was recovered by gravity except for Sulphide Sample 1 which had negligible gravity recoverable gold.
|Table 2. Summary of Composite Samples prepared by Wardell Armstrong|
|Kilo Goldmines Ltd||Wardell Armstrong|
|Sample Weight (kg)||Au (g/t)
50 g FA-AA
|Oxide 3 & 4||SADD0025/31||34.05||55.4||2.13||1.85||1.49|
|Note:||the mineralized interval and Kilo weighted average gold values in Table 2 are pursuant to calculations by Kilo.|
- The cyanide leach pH was controlled at 10.5 with lime, the oxidant was air and the free cyanide levels were targeted at 1% or 1 g/L but actual free cyanide levels varied significantly.
- Bond Ball Mill Work Indices ("BBMWI") tests were carried out on one composited oxide sample,from all of the oxide material, and on one composited sulphide sample, from all of the sulphide material, were determined to be in the order of 10.5 kilowatt hours per tonne ("kWh/t') and 11.8 kWh/t respectively. The test work has not conclusively determined the BBMWI for the various rock types hosting the gold, however preliminary indications are that they are significantly lower than expected; hence, an unexpected positive for process selection and possibly lower than expected project power requirements will be realized.
- Wardell Armstrong analyzed for gold by Atomic Absorption (AA) whereas Kilo assayed gold by FA-AA. It is unknown if the higher composite gold grades obtained by Wardell Armstrong are a reflection of the analytical methods, or, if the Kilo gold values are understated.
|Wardell Armstrong recommended the following:|
- Conventional cyanide leach testing on gravity tailings to optimise grind size and solution strength
- Chemical and mineralogical analysis of gravity tailings to determine if deleterious elements are present
- Grind size testing on gravity separation stage and effects on tailings leach
- Bulk test to result in sufficient gravity concentrate for leach testing
- Thickening and filtration of leached tailings to determine material transport and deposition requirements
- Chemical and mineralogical analysis
- Diagnostic leaching
- Optimise gravity tailings leach process as per oxide material
Preparation of Submitted Drill Core Samples:
Kilo submitted 191 samples of one-quarter diamond drill core from 10 gold bearing zones intersected by seven drill holes. Each sample represented the same drill hole interval as the previously submitted half-core samples to ALS Chemex Laboratories for gold analysis by FA-AA on a 50 g pulp. The samples were obtained by cutting, with a diamond blade saw, the half-core retained following the initial sampling. Each sample was assigned a pre-labelled number and placed into a plastic bag and stapled shut. The individual samples were packed into larger bags and shipped from the DRC to Entebbe by a commercial carrier and from Entebbe, Uganda to London, England by commercial air-cargo.
About the Somituri Project
The recent Inferred Mineral Resource Estimate (see PR dated March 15, 2012) concluded that the Adumbi Gold Deposit hosts 1.87 million ounces of gold grading 1.63 g/t at a 0.50 g/t cut-off of which; 33%, 14% and 53% is attributable to the oxide, transition and sulphide types respectively.
Records from the colonial era, unverified by the Company, indicate that during the 1940s until its closure in 1958 the combined production from the Adumbi and Bagbaie mines totalled approximately 200,000 ounces of gold; the Adumbi gold was hosted in quartz vein ore reported to average 11 g/t gold and the Kitenge and Manzako mines produced approximately 100,000 ounces of gold prior to about 1942. The historical data is non NI43-101 compliant, unverified by the Company, should not be relied upon, and is presented for information purposes only.
Kilo Goldmines Ltd. is a Canadian gold exploration company that is listed on the TSX Venture Exchange under the symbol 'KGL' and on the Frankfurt Exchange under the symbol '02K'. The Company has over 7,000 square kilometres of favourable Archaean Kabalian greenstone in the Kilo-Moto area in the Democratic Republic of the Congo. Kilo's principal focus is to advance its projects from exploration through feasibility to project development and ultimately to full production in a socially and environmentally responsible manner. The Company owns a 71.25% interest in the Somituri Project.
The Company is also working on a number of other prospective areas which contain historical workings in the same region. It also has a joint venture with Rio Tinto Ltd. on potential iron ore licences in north-eastern DRC.
About Wardell Armstrong
Wardell Armstrong International is a UK based provider of professional and technical consulting services to the mining industry offering a wide range of expertise including mineral resource evaluation, mining engineering, mineral processing & metallurgy, mine waste management, geotechnical engineering, water management, sustainability, energy, environmental & social management, mine closure & post-mining regeneration.
The company employs over 350 people worldwide from offices based in the UK, Russia and Kazakhstan and although focused principally on the CIS, Europe and Africa, has been actively involved in projects in over 70 countries.
The selection of drill core samples submitted to Wardell Armstrong together with their lithology, gold values and collection methodology disclosed in this press release was planned, verified and supervised by the Company's geological consultant Stanley Robinson. Stanley Robinson, M.Sc., P.Geo is also the 'qualified person' (as that term is defined under National Instrument 43-101) of the Company who has reviewed and approved the scientific and technical information contained in this release with respect to the selection and submission of the drill core samples for metallurgical testing.
The Metallurgical Test work carried out by Wardell Armstrong was under the supervision of Dr. Phil Newell, BSc (ARSM), PhD (ACSM). CEng, FIMMM, Director with Wardell Armstrong International. Phil Newell is also the 'qualified person' (as that term is defined under National Instrument 43-101) who has reviewed and approved the scientific and technical information contained in this release with respect to the metallurgical testing.
This news release may contain forward looking statements concerning future operations of Kilo Goldmines Ltd. All forward looking statements concerning the Company's future plans and operations, including management's assessment of the Company's project expectations or beliefs may be subject to certain assumptions, risks and uncertainties beyond the Company's control. Investors are cautioned that any such statements are not guarantees of future performance and that actual performance and exploration and financial results may differ materially from any estimates or projections.