Preliminary Metallurgical Work TORONTO, ONTARIO--(Marketwired - March 6, 2014) - Lexam VG Gold Inc. (the "Company", "Lexam") (TSX:LEX)(FRANKFURT: VN3A)(OTCQX:LEXVF) is pleased to report positive results from preliminary metallurgical testwork, indicating recoveries from 90.7% to 98.5%. Drill core samples were analyzed from our four gold projects in Timmins, Ontario (Buffalo Ankerite, Paymaster, Fuller and Davidson Tisdale). These results will be utilized in the ongoing Preliminary Economic Assessment ("PEA") examining the open pit potential of the gold projects.
The preliminary metallurgical results indicate:
- High recoveries between 90.7% and 98.5% for traditional gravity concentration and cyanide leach processes, in line with historic metallurgical results;
- Recoveries for both processes occurred at relatively coarse grind sizes, with P80 of 68 to 82 microns, while a more commonly used finer grind would likely yield higher recoveries;
- Maximum cyanide leach recoveries were achieved in just over 24 hours residence;
- The samples had favourable characteristics, including low reagent consumption and short leach times;
- Recovery increases with finer grind, indicating the potential for improved results with additional testwork.
Lexam has NI 43-101 resource estimates for the four projects. The recently released resource estimates were completed to better define the near surface resource within a potential open pit shell. The updated resources were classified into two categories: Open Pit and Underground (Table 2).
A Preliminary Economic Assessment is being conducted to determine the economic viability of open pit mining on each of the properties. The Open Pit Gold Resource Estimate on the four projects is:
| Open Pit Measured and Indicated | - | 761,400 oz Au @ 1.91 g/t Au |
| Open Pit Inferred | - | 358,400 oz Au @ 1.78 g/t Au |
| (A cut-off of 0.51 g/t Au was utilized based on US$1,600/oz Au price and an exchange rate of US$1.00=C$1.00. |
| See Note on Mineral Resources at the end of this press release.) |
For abbreviations used please see List of Abbreviations at the end of this press release.
Recent Metallurgical Testwork
The study was conducted by SGS Minerals Services ("SGS") at its Lakefield, Ontario facility. Composite samples were submitted by Lexam to SGS for a metallurgical investigation into the recovery of gold. The 5 samples of diamond drill core utilized in the metallurgical testing represent composite intervals from the open pit sections of the properties (one sample was tested for each Buffalo Ankerite North Zone, Buffalo Ankerite South Zone, Paymaster, Fuller and Davidson Tisdale). Most of the properties have either historic metallurgical studies or a history of gold milling indicating favourable metallurgical properties on grades of underground tenure. The objective of the present studies was to confirm that the favourable recovery extended to the lower grades of the open pittable resources. The results confirmed favourable metallurgical recovery of the lower grades contained within the proposed open pits, similar to the gold recovery of the historic underground mining.
The selected composite samples originated from drill holes within the resource optimized pit shells and were selected to be representative of the gold grades of the open pit resource at the Timmins projects. The gold head analysis confirmed the grades anticipated by Lexam, with a representative range of low assays, 0.5 to 1.5 g/t Au, within the composite. The highlighted column "Grav + CN" in Table 1 that follows indicates the overall recovery that can be expected. The results were favourable indicating recoveries from 90.7% to 98.5%.
| Table 1. Summary of Cyanidation Test Results |
| |
| Test No. | P80, um | Reagent, | Au Extraction/Recovery, % | Au Residue, g/t | Au Head, g/t |
| kg/t of CN feed |
| Addition | Consumption | 4 | 7 | 24 | 48 | Grav | Grav
+ CN | A | B | Average | CN
Calc | Grav
Calc | Direct |
| NaCN | CaO | NaCN | CaO |
| Buffalo Ankerite North Zone Composite G-2 Tailing |
| CN-1 | 103 | 0.83 | 0.54 | 0.08 | 0.51 | 82 | 85 | 88 | 88.9 | 13.5 | 90.4 | 0.42 | 0.38 | 0.4 | 3.6 | 4.15 | 3.60 |
| CN-2 | 68 | 0.97 | 0.41 | 0.29 | 0.39 | 88 | 91 | 93 | 93.3 | 94.2 | 0.25 | 0.23 | 0.24 | 3.59 |
| |
| Buffalo Ankerite South Zone Composite G-1 Tailing |
| CN-3 | 149 | 0.79 | 0.52 | 0.14 | 0.51 | 75 | 78 | 85 | 86.6 | 17.7 | 89 | 0.27 | 0.26 | 0.27 | 1.98 | 2.36 | 2.20 |
| CN-4 | 82 | 1.38 | 0.41 | 0.72 | 0.39 | 79 | 87 | 93 | 92.4 | 93.7 | 0.14 | 0.15 | 0.15 | 1.9 |
| |
| Paymaster Composite G-3 Tailing |
| CN-5 | 131 | 0.77 | 0.41 | 0.07 | 0.4 | 61 | 66 | 72 | 73.2 | 13.6 | 76.8 | 0.54 | 0.5 | 0.52 | 1.94 | 2.31 | 2.20 |
| CN-6 | 74 | 1.44 | 0.28 | 0.7 | 0.24 | 70 | 84 | 90 | 90.5 | 91.8 | 0.2 | 0.19 | 0.2 | 2.05 |
| |
| Fuller Composite G-4 Tailing |
| CN-7 | 135 | 0.75 | 0.34 | 0.05 | 0.32 | 64 | 68 | 76 | 79.7 | 37 | 87.2 | 0.2 | 0.23 | 0.22 | 1.06 | 1.68 | 2.20 |
| CN-8 | 65 | 0.76 | 0.37 | 0.05 | 0.35 | 76 | 80 | 85 | 85.3 | 90.7 | 0.16 | 0.15 | 0.16 | 1.06 |
| |
| Davidson Tisdale Composite G-5 Tailing |
| CN-9 | 137 | 0.75 | 0.55 | 0.17 | 0.55 | 49 | 62 | 91 | 94.8 | 24.2 | 96.1 | 0.03 | 0.1 | 0.05 | 0.87 | 1.23 | 0.7 |
| CN-10 | 68 | 1.47 | 0.54 | 0.82 | 0.53 | 58 | 77 | 94 | 98 | 98.5 | 0.02 | less than 0.02 | 0.02 | 0.98 |
The test conditions applied were as follows:
Cyanidation Test Conditions
| | | | | | | | | |
| Primary Grind | = | | 10 kg Rod Mill | | Retention Time | = | | 48 hours |
| Regrind | = | | 2 kg Rod Mill | | Pre-airation | = | | not applicable (na) |
| Size Target | = | | variable | | Dissolved Oxygen | = | | na |
| Pulp pH | = | | 10.5 - 11 (maintained with lime) | | Carbon | = | | na |
| Cyanide Concentration | = | | 0.50 g/L NaCN | | Temperature | = | | ambient |
| % Solids | = | | 40% solids | | DO target | = | | na |
| | | | | | | | | |
The Program was conducted by SGS Minerals Services at its Lakefield facility, under the supervision of Vivien Delaney, Metallurgist - Gold Group, Metallurgical Operations.
The metallurgical report recommended that the potential to reduce milling costs and improve gold recovery through optimizing these techniques still exists with further testing.
Comparison to Historic Metallurgy
The Fuller and Davidson Tisdale deposits saw development during the period 1984 - 1988, which included the development of a ramp to access the ore and the mining and processing of a bulk sample. Extensive metallurgy was conducted during this period at both an independent laboratory, as well as at local mills that processed the bulk sample. The results obtained during this extensive metallurgical testing of underground samples compares very favorably with the recent results obtained by SGS.
The Fuller metallurgical testwork indicated recoveries utilizing direct cyanidation of between 85% to 97% gold extraction at the independent laboratory and 93.8% at the mill lab. Reagent consumption was characterized as low and leach times were within the normal thresholds.
Davidson Tisdale metallurgical testwork completed at a local mill as well as detailed work completed at an independent laboratory indicated that direct cyanidation yielded a high gold extraction (97% to 98% recovery), at a relatively coarse grind and with relatively low reagent requirements.
The Buffalo Ankerite North and South Zones had historic underground mining of over 1 million ounces of gold as below:
| | Years | Gold
(ounces) | Gold
(opt) | Ore Milled
(tons) |
| Ankerite/March | 1926-1935 | 61,039 | 0.19 | 317,769 |
| Buffalo Ankerite | 1926-1953, 1978 | 957,292 | 0.19 | 4,993,929 |
Production statistics from the Ontario Department of Mines annual reports indicate that gold recoveries of 92% to 95% were achieved during the production period, using the standard Merrill Crowe process.