A preliminary economic study dated November 7, 2011, proposing a combined gravity, flotation, and cyanidation processing route for the Amizmiz gold property in Morocco, based on 2003 metallurgical testwork on Az structure samples.
Report context
This technical report, presents a conceptual pre-production work program and preliminary economic study for Maya Gold and Silver Inc. on the Amizmiz gold property, Marrakech Province, Kingdom of Morocco, with an effective date of November 7, 2011. The processing section relies on metallurgical testing conducted in 2003 by SEGM on 100 kg samples from diamond drill holes on the Az, T, and G zones. Tests were performed by Reminex's Research Centre and Laboratory at the Guemassa Mine. The Az structure sample, considered most representative of the polymetallic, oxidized, gold-bearing veins in Lower Cambrian limestone, assayed 28.5 g/t Au. The study is pre-production and conceptual; the proposed mill design and recoveries are based on assumptions requiring full testing before production.
Processing route
The proposed processing route combines three standard gold recovery methods: gravity concentration using a Knelson concentrator, flotation, and cyanidation. The circuit is designed for a daily ore processing capacity of 150 t/day, based on an Inferred Mineral Resource of 242,000 t of ore. A conservative diluted head grade of 9.5 g/t Au was adopted, below the calculated resource grade of 12.94 g/t Au.
Crushing and grinding
The overall crusher unit consists of an ore funnel, jaw crusher, screens, secondary crusher, stockage funnels, and conveyor belts. The circuit is described as a classic flotation process for 150-200 t/day with gravimetry after crushing. Grinding to 100 μm (D80) for flotation and cyanidation, and 360 μm (D100) for gravity concentration, was used in testwork.
Gravity concentration
The 2003 gravimetric test on Az zone material used a Knelson concentrator with the following parameters: granulometry 360 μm (D100), solid concentration 30%, solid flow 30 kg/h, pressure 4.5-5 PSI. The test achieved 30% gold recovery into a concentrate grading approximately 300 g/t Au. In the proposed design, the gravity circuit yields a 2.5% weight recovery corresponding to 30% gold recovery into the concentrate. Based on 150 t/day at 9.5 g/t Au, this represents 3.7 t of concentrate containing 429 g of gold daily.
Flotation
Flotation testwork on Az material was conducted at 100 μm (D80), 30% solids, natural pH, mixing speed 1400 r/min. Reagent additions were: roughing concentrate – S 5415 at 35 g/t and MIBC at 30 g/t; finishing concentrate – AXK at 150 g/t. The roughing concentrate graded 64 g/t Au with a combined roughing and finishing recovery of 77%. The proposed design assumes the flotation circuit receives the remaining 146 t/day (1,000.5 g Au) after gravity recovery. The report notes that a 40% weight recovery is assumed for flotation, but acknowledges this is very high; a more typical 11.6% weight recovery would produce 16.9 t of concentrate containing 774.2 g of gold at 77% recovery. Flotation rejects (87.4 t at 40% weight recovery, or 129 t at 11.6% weight recovery) are sent to decantation basins.
Cyanidation
Cyanidation testwork was performed at 100 μm (D80), 33% solids, pH 11.3, 24-hour duration, with 3 g/L sodium cyanide. The test achieved 97% gold recovery. The proposed design includes an independent cyanidation CIP fusion circuit. The 97% figure is a cyanidation-stage assumption, not an overall plant recovery.
Products and tailings
The end products are two concentrates: one from gravity and one from flotation. The gravity concentrate grades approximately 300 g/t Au; the flotation roughing concentrate grades 64 g/t Au. Flotation rejects report to decantation basins. Energy and water requirements were not calculated in the study. A list of standard equipment for a 150-200 t/day flotation/gravimetric plant is provided in the report, covering crushing, grinding, gravimetry, flotation, and decantation/filtration processes.
Key reported parameters
| Parameter | Value | Basis |
|---|---|---|
| Mill capacity (design) | 150 t/day | Conceptual design assumption based on 242,000 t Inferred Resource |
| Head grade (design) | 9.5 g/t Au | Conservative assumption, after dilution |
| Gravity recovery (testwork) | 30% Au | 2003 Az sample, Knelson concentrator |
| Gravity concentrate grade (testwork) | ~300 g/t Au | 2003 Az sample |
| Gravity weight recovery (design) | 2.5% | Design assumption |
| Flotation recovery (testwork) | 77% Au | 2003 Az sample, combined roughing + finishing |
| Flotation roughing concentrate grade (testwork) | 64 g/t Au | 2003 Az sample |
| Cyanidation recovery (testwork) | 97% Au | 2003 Az sample, 24h at 3 g/L NaCN |
| Grind size for flotation/cyanidation (testwork) | 100 μm (D80) | 2003 test parameters |
| Grind size for gravity (testwork) | 360 μm (D100) | 2003 test parameters |
Project website: https://www.northernminer.com/news/maya-gold-silver-turns-to-moroccos-silver-and-gold-riches/1000607433/
Technical qualifications
This study is a conceptual pre-production work program dated November 7, 2011. All metallurgical data derive from 2003 testing on a single 100 kg Az structure sample assaying 28.5 g/t Au. The sample is described as representative of polymetallic, oxidized veins in limestone, but testwork on the T and G zones is not reported in detail. The 97% cyanidation recovery is a stage recovery from testwork, not a demonstrated overall plant recovery; stage recoveries are not additive. The proposed 150 t/day mill capacity and circuit design are based on Inferred Mineral Resources, which are too speculative geologically to have economic considerations applied. The study states that adjustments and modifications will occur after new testing at ONHYM (Office National des Hydrocarbures du Maroc). Energy and water requirements were not calculated. The flotation weight recovery assumption of 40% is acknowledged as very high compared to the usual 10-15% for flotation circuits. The study is a preliminary economic assessment; it is not a feasibility study and does not demonstrate economic viability.
Source: , "Pre-production Work Program, Preliminary Economic Study, The Amizmiz Gold property, Marrakech Province, Kingdom of Morocco, MAYA GOLD AND SILVER INC.," effective date November 7, 2011, Items 13 and 17..
