The metallurgical program will be included as part of Probe’s anticipated Preliminary Economic Assessment ("PEA").
Probe’s metallurgical program has been on-going for the last 3 years and has generated sufficient input data to perform a series of process route trade-off studies, in particular to compare the two main process options: 1) gravity + whole ore leach ("WOL"); and 2) gravity + flotation + leach of flotation residues and reground flotation concentrate ("FLOT") (irrespective of the downstream flowsheet, gold gravity recovery is included in each option). The metallurgical work is based on drill core samples taken from representative drill holes in the Borden Gold project.
The results of the trade-off studies indicate that the WOL option may be superior, subject to further analysis and the PEA. The tests also established that the optimum grind objective for the WOL option was 75 µm.
The resulting metallurgical recovery curve (WOL at 75 µm) is presented in Figure 1. This updated grade recovery curve shows an overall improvement over the curve released in April 2013.
Completed work for the anticipated PEA includes metallurgical and comminution testing on the lower-grade zone (open pit) and the higher-grade zone (underground). Metallurgical tests include gold extraction from gravity, flotation and leach from different geo-domain composites, fine regrind, settling, and In-Line Reactor (ILR) test work. The comminution test program includes: Drop-Weight Test (DWT), SAG Mill Comminution Test (SMC), Bond Ball Mill Work Index (BWi), Rod Mill Work Index (RWi), Abrasion Index (Ai), Unconfined Compression Test (UCS) and Low Energy Impact Test.
Metallurgical testwork is continuing in 2014 in order to continue strengthening the bases for the definition of the process design criteria.
Mr. Yves Dessureault, Chief Operating Officer of Probe, states: "These metallurgical results are very encouraging and continue to improve. There is probably some further upside for gold extraction at higher gold grades and this will be the focus of the 2014 metallurgical program".
The metallurgical testing was carried out under the supervision of BBA Inc. and was conducted by SGS Mineral Services (Lakefield) and Process Research Ortech Inc. (Mississauga). The contents of the above have been approved by Mr. Jacques McMullen, P.Eng, Qualified Person of BBA Inc., independent consultants to Probe.