Overview
Stage | Preliminary Economic Assessment |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
- Filter press plant
- Smelting
- Heap leach
- Carbon in column (CIC)
- Carbon adsorption-desorption-recovery (ADR)
- Elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
- Rotary kiln & Electric furnace
|
Mine Life | 10 years (as of Jan 1, 2020) |
Latest News | GMV Minerals Inc. Closes Non-Brokered Financing November 26, 2020 |
Source:
p. 37
Source:
p.62,63,68
Summary:
The property occurs on the east-side of the Dragoon Mountains and is underlain by mixed mafic to felsic peralkaline volcanic rocks. A fault of regional extent bounds the property to the west, and alluvium covers the eastern, northern, and southern extents of the property. A prominent hill, the Mexican Hat Hill dominates, and several smaller hills define the physiography of the property. Several structures of more local extent can be observed on the flanks of the hills on the property and defined by geophysics.
Gold mineralization is associated with moderate to strong oxidized zones of hematite and limonite. Hematite and limonite are directly related to and fill, in part, dominant NE/SW fault and related fractured zones including secondary NW/SE fault and fractured zones. Hematite may be the result of low-temperature alteration of primary or secondary magnetite. Limonite, a secondary mineral after pyrite is common in surface oxidized zones. Malachite and azurite were observed in several locations across the property within trachyte andesite (Webb, 2015). In addition, the main elevated metal assemblage from assay results include Au, Ag, As, Hg and Sb. Limits of mineralized zones have not been determined. No sulphides or visible gold has been identified from surface exploration campaigns.
Three main types of alteration are recognized on the Mexican Hat property. First, carbonate alteration is the most common within all Tertiary volcanic rocks mapped on the property. Carbonate alteration is pervasive and ranges from weak to strong. Second, weak propylitic alteration (epidote + weak chlorite in part) was observed and is association with zones of fracturing accompanied by strong hematization. Third,weak to moderate silicification was observed within and adjacent to some extensional structures. Sericite and K-Feldspar alteration typical of low sulphidation alkali epithermal deposits may be present but these types of alteration were not observed. A Pima or suitable alteration survey may be useful in identifying all alterations present in the main elevated gold/silver zones.
Porphyry-style mineralization including skarn-type end members containing economically recoverable copper, gold, and sometimes lead, zinc, silver and molybdenum occur in this part of Arizona. The Courtland Gleeson district extends up to and may include the Mexican Hat Property. This mineralization is primarily hosted within Mesozoic sediments and younger intrusions. Placer gold deposits occur in places in washes near the base of the Turquois Mountains.
Younger mineralization hosted in rocks including Tertiary volcanic rocks occur in the area, and at Mexican Hat. The association of alkaline to subalkaline volcanic rocks and the presence of low sulphide concentrations together with the geochemistry of these rocks indicates that the Mexican Hat Property is a low sulphidation epithermal gold deposit.
Source:
p.158,163,169
Summary:
The PEA presented in this report considers open-pit mining of the Mexican Hat gold deposit.
The design slope parameters use an 18 m height between catch benches separated by three benches each of 6.0 m height, a 66° bench face angle, and 10 m catch benches or berms. This provides for a 45° inner-ramp angle. Table 16-3 also shows the design parameters used for waste dumps. The waste dump design includes 12 m lift heights with 12 m catch benches and a 34° slope between benches to achieve an overall slope of 2.5 horizontal to 1.0 vertical.
Mexican Hat pits were designed with five phases. Phase 1 mines the larger main portion of the deposit. Phase 2 continues to expand the main portion of the deposit. Phase 3 expands the main pit to the south and Phase 4 achieves the full depth and extents of the main pit. Phase 5 mines a satellite pit located to the south of the main deposit.
The Mexican Hat pits have a total of 61.1 million tonnes of waste associated with the material to be processed, and thus has an overall strip ratio of 1.87 tonnes of waste per tonne leached.
The total mining rate would ramp up from 5,000 tonnes per day to about 26,500 tonnes per day over a period of 12 months. A maximum of 46,000 tonnes per day is used in later years when the stripping becomes more significant
Source:
p.175
The Mexican Hat project is designed to crush 3.5 million tonnes of resources per annum at a daily rate of 10,000 t/d for 350 days per year. The 2-stage crushing circuit is designed at a 75% availability, equivalent to a crushing rate of about 1,110 t/h. The crushing circuit is designed to crush run-of-mine material in 2 stages from 100% passing feed size of 1,400 mm down to a product at 80% passing 38 mm. The crushing plant will be supplied, operated, and maintained by the crushing contractor.
The crushed material will be conveyed from the crushing plant by a radial stacking conveyor to a crushed material stockpile. The stockpile will have 24 hour live capacity. Crushed material is reclaimed from beneath the stockpile by two reclaim feeders to an overland conveyor where lime will be added from a silo at the required dosage. The crushed material and lime will be conveyed to the heap leach pad for stacking onto the heap leach pad.
Processing
- Filter press plant
- Smelting
- Heap leach
- Carbon in column (CIC)
- Carbon adsorption-desorption-recovery (ADR)
- Elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
- Rotary kiln & Electric furnace
Flow Sheet:
Summary:
For Mexican Hat, the metal recovery from heap leaching will be in an ADR circuit, regeneration, and refinery plant. The plant will have an operation availability of 92% and will be supplied as a vendor package with all the equipment necessary to recover gold from the PLS.
Pregnant solution will gravity flow through the heap leach and be collected in a lined pregnant solution pond. Pregnant solution will be pumped to two trains of 5 CIC in series (total of 10 CIC tanks) where gold in solution is adsorbed onto the carbon. Loaded carbon is advanced in the CIC circuit counter current to the flow of solution. This ensures that the highest-grade gold in solution is in contact with the highest grade loaded carbon and that the lowest grade solution is in contact with the lowest grade carbon to ensure carbon lading efficiency. Loaded carbon is transferred daily from the CIC to the 3 tonne acid wash and elution circuit.
The loaded carbon acid wash is at atmospheric pressure and acid wash solution is circulated to the bottom of the tank and overflows back into the acid wash solution tank at a rate of 2 bed volumes per hour for 1.5 bed volumes. The carbon is then rinsed with water for 30 minutes. After rinsing, the carbon is transferred to the 3 tonne strip vessel where the carbon is stripped under pressure and about 145°C. Strip solution is pumped via the bottom of the strip vessel and flows to the electrowinning circuit where gold is plated onto steel wool. Typically, eleven bed volumes of strip solution are required at a pumping rate of 2 bed volumes per hour.
Stripped carbon will be transferred to the horizontal rotary kiln for regeneration at 750°C. The carbon should be regenerated in the kiln after every desorption stage otherwise carbon loading efficiency will decrease and gold losses in solutions in the CIC will increase.
The gold rich eluate is pumped to the electrowinning cells where a current is passed so that the gold will plate onto the steel wool cathode. The barren solution from electrowinning will recirculate back to the strip solution tank to be used for mixing strip solution. A 20% bleed of barren solution is recommended to avoid buildup of contaminants.
Gold contained sludge from the electrowinning cells will be washed off the cathode and pumped to a plate and frame filter press. Filter cake will be placed in trays into a drying oven. Dried filter cake will be put through mercury retort prior to mixing with smelting flux and put into the electric induction furnace. The slag layer containing impurities will be removed prior to pouring the gold into molds to produce gold doré bars. The doré bars will be cooled, cleaned, sampled, and shipped to market.
HEAP LEACH PAD DESIGN
The HLF, which includes the HLF, PLS, and event pond is planned to be located north of the proposed pit. The HLF will be constructed in two phases and has been designed for a nominal production rate of 3,500,000 t of mineralized material per year (10,000 tpd) for a total heap capacity of 32.6 Mt assuming a heap bulk density of 1.5 t/m3. The mineralized material will be mined by a standard open pit mining method, crushed to 80% minus 38 mm, and placed through transport and stacking on the HLF in 10-m-high lifts using a conveyor/stacking system. The HLF is anticipated to have a maximum height of 72 m and an overall slope of 2.5H:1V.
The HLF will consist of:
- Liner System;
- Crushed Material Stacking;
- Collection Ponds;
Recoveries & Grades:
Commodity | Parameter | Avg. LOM |
Gold
|
Recovery Rate, %
| 88 |
Gold
|
Head Grade, g/t
| 0.57 |
Projected Production:
Commodity | Units | Avg. Annual | LOM |
Gold
|
koz
| 53 | 525,062 |
All production numbers are expressed as metal in doré.
Operational Metrics:
Metrics | |
Stripping / waste ratio
| 1.87 * |
Daily ore mining rate
| 26,500 t * |
Waste tonnes, LOM
| 61,115 kt * |
Ore tonnes mined, LOM
| 32,632 kt * |
Total tonnes mined, LOM
| 93,748 kt * |
Daily processing rate
| 10,000 t * |
Tonnes processed, LOM
| 32,632 kt * |
Annual processing rate
| 3,500 kt * |
* According to 2020 study.
Reserves at June 22, 2020:
Cut-off 0.20 g/t Au
Category | Tonnage | Commodity | Contained Metal |
Inferred
|
36,733,000 t
|
Gold
|
688,000 oz
|
Commodity Production Costs:
| Commodity | Units | Average |
All-in sustaining costs (AISC)
|
Gold
|
USD
|
1,136 / oz *
|
C1 cash costs
|
Gold
|
USD
|
951 / oz *
|
Assumed price
|
Gold
|
USD
|
1,600 / oz *
|
* According to 2020 study / presentation.
Operating Costs:
| Units | 2020 |
OP mining costs ($/t milled)
|
USD
| 7.69 * |
Crushing costs ($/t milled)
|
USD
| 2.49 * |
Processing costs ($/t milled)
|
USD
| 6.81 * |
G&A ($/t milled)
|
USD
| 0.8 * |
Total operating costs ($/t milled)
|
USD
| 15.3 * |
* According to 2020 study.
2020 Study Costs and Valuation Metrics :
Metrics | Units | LOM Total |
Initial CapEx
|
$M USD
|
67.8
|
Sustaining CapEx
|
$M USD
|
13
|
Closure costs
|
$M USD
|
25.2
|
Total CapEx
|
$M USD
|
80.9
|
OP OpEx
|
$M USD
|
250.8
|
Processing OpEx
|
$M USD
|
222.2
|
G&A costs
|
$M USD
|
26.1
|
Total OpEx
|
$M USD
|
499.2
|
Royalty payments
|
$M USD
|
1.5
|
Pre-tax Cash Flow (LOM)
|
$M USD
|
220.4
|
After-tax Cash Flow (LOM)
|
$M USD
|
153
|
Pre-tax NPV @ 5%
|
$M USD
|
150.6
|
After-tax NPV @ 5%
|
$M USD
|
100
|
After-tax NPV @ 10%
|
$M USD
|
64
|
Pre-tax IRR, %
|
|
39.3
|
After-tax IRR, %
|
|
29.3
|
Pre-tax payback period, years
|
|
2.8
|
After-tax payback period, years
|
|
2.8
|
Mine Management:
Job Title | Name | Profile | Ref. Date |
Consultant - Mining & Costs
|
Tom Dyer
|
|
Oct 20, 2020
|
Consultant - Recovery Methods & Costs
|
Francisco Barrios
|
|
Oct 20, 2020
|
Staff:
Employees | Contractors | Total Workforce | Year |
67
|
120
|
187
|
2020
|
Corporate Filings & Presentations:
News:
News | Date |
GMV Minerals Inc. Closes Non-Brokered Financing
|
November 26, 2020
|
GMV Minerals Inc. Announces Non-Brokered Financing
|
November 23, 2020
|
GMV Minerals Inc. Announces SEDAR Filing of Mexican Hat Preliminary Economic Assessment
|
November 20, 2020
|
GMV Minerals Inc. Announces PEA Results at Mexican Hat Gold Project in S.E. Arizona
|
November 3, 2020
|
GMV Minerals Inc. Closes Over Subscribed Non-Brokered Financing
|
April 21, 2020
|
GMV Minerals Inc. Announces Non-Brokered Financing
|
April 14, 2020
|
GMV Minerals Inc. Announces Multiple Broad Domains Intercepted Including 30.5 Metres Grading 1.47 gpt Gold and 45.7 Metres Grading 0.61 gpt Gold
|
September 10, 2019
|
GMV Minerals Inc. Reports Multiple High-Grade Assay Results in Drilling Program--1.237 gpt Gold over 18 Meters
|
August 7, 2019
|
GMV Minerals Inc. Announces Non-Brokered Financing
|
April 25, 2019
|
GMV Minerals Files PEA Report for the Mexican Hat Gold Project
|
December 19, 2018
|