Antioquia Gold Inc. (TSX VENTURE:AGD) today announced the results of the preliminary metallurgical assessment completed on the gold bearing rocks on its flagship property as well as Acid Based Accounting tests, the Cisneros Project located in Antioquia, Colombia.
The various recovery methods tested indicate that gold recoveries in excess of 90% are easily achievable.
The metallurgical testing was performed by G&T Metallurgical Services of Kamloops, B.C., and the Acid Based Accounting tests by Inspectorate America Corp. of Sparks, Nevada.
"We are highly encouraged with the results from our preliminary metallurgical testing at Cisneros Project," commented President and CEO, Richard Thibault. "It indicates to us that standard and simple mineral processing techniques can be applied to the ore. Further testing will be conducted once bulk samples can be obtained to determine optimal crushing and grinding size, the flotation parameters and the leaching process."
Gold Recovery
Four composite samples from two general locations within the Cisneros Project were collected and tested by G&T Metallurgical Services.
Three recovery methods were conducted on each of the four composite samples:
- gravity concentration;
- flotation; and
- cyanide leaching.
The gold content in the three composites from the current exploration areas of Guayabito-Guaico-Nus were relatively high (17.9 g/t to 43.5 g/t), while the sample from the Sur America area, located approximately 3 kilometres to the north of the other three composite samples, in a different geological setting, contained 2.98 g/t.
All composites, with the exception of the one from Sur America, responded well to gravity concentration with recoveries ranging from 26% to 48% and concentrates grading from 1,194 g/t to 3,680 g/t gold.
The same three ores that responded well to gravity concentrate also responded well to cyanide leaching with extractions ranging from 94% to 97%. The material was first ground to a nominal K80 of 100 microns. Cyanide consumption was in the range of 0.2 kg/t to 1.2 kg/t with the exception of Guaico, which was 6.1 kg/t, likely due to the presence of some reactive copper minerals.
Flotation gave high recoveries for all four samples with recoveries to a bulk concentrate of 88% to 97%. Concentrate grades were 143 g/t to 578 g/t gold excluding Sur America which, with its lower feed grade, gave a 50 g/t concentrate.
A variety of options appear to be available for treating the ore and maximizing the recovery of gold. All three processes are standard and widely used in gold mining. The Company expects a combination of the three processes (gravity concentration, flotation and cyanide leaching) would be applied to ensure maximum recovery of the gold. Gold companies in Colombia typically favour the gravity + flotation concentration circuit to produce a high grade concentrate. The combined concentrates then undergo cyanide leaching that offers certain advantages.
Further testing will be conducted once bulk samples from underground exploration tunnels can be obtained during 2011. These sets of testing will be to determine optimal crushing and grinding size, the flotation parameters and the leaching process.
Acid Based Accounting Results
A total of 12 random samples in waste rock and some ore zones were sent to Inspectorate America Corp. to be tested to determine its acid generating potential in the waste dumps and tailings ponds.
The average pH of the 12 samples was 8.62 with an average total sulfur content of 1.40%. The majority of the samples were not net acid generators, but some were and further studies on appropriate action will be necessary to prevent possible acid production.
Qualified Person
This report and the tests were conducted under the guidance of Dr. John Thomas, P.Eng., a member of the Association of Professional Engineers and Geoscientists of British Colombia and a qualified person pursuant to National Instrument 43-101, Standards for Disclosure for Mineral projects; he has also reviewed the technical information disclosed in this news release.
Source: Antioquia Gold Inc.