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Venezuela
Siembra Minera (Brisas-Cristinas) Project

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 Location:
5 km W from Las Claritas, Venezuela

  Project Contacts:
999 W. Riverside Ave., Suite 401
Spokane
Washington, United States
99201
Phone  ...  Subscription required
Fax(509)-623-1634
WebsiteWeb
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  • Overview
  • Owners
  • Geology
  • Mining
  • Processing
  • Production
  • Reserves
  • Costs & Financials
  • Fleet
  • Personnel
  • Filings & News

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Overview

StagePreliminary Economic Assessment
Mine TypeOpen Pit
Commodities
  • Gold
  • Copper
  • Silver
Mining Method
  • Truck & Shovel / Loader
Processing
  • Gravity separation
  • Flotation
  • Agitated tank (VAT) leaching
  • Carbon in leach (CIL)
  • Carbon in pulp (CIP)
  • AARL elution
  • Carbon adsorption-desorption-recovery (ADR)
  • Solvent Extraction & Electrowinning
  • Cyanide (reagent)
Mine Life45 years (as of Jan 1, 2018)
The Project is a combination of the Brisas and Cristinas properties into a single project now called the Siembra Minera Project.
Latest NewsGold Reserve Provides Positive PEA on Siembra Minera Project     March 20, 2018


Owners

Source: p. 9
CompanyInterestOwnership
Gold Reserve Inc. 45 % Indirect
Corporacion Venezolana De Mineria, S.A. 55 % Indirect
Empresa Mixta Ecosocialista Siembra Minera, S.A (operator) 100 % Direct
The operating company Empresa Mixta Ecosocialista Siembra Minera, S.A., which holds the rights to the Siembra Minera Project, is a mixed capital company with 55% being owned by a Venezuelan state entity [owned by the Bolivarian Republic of Venezuela through the Corporación Venezolana de Minería] and 45% by GR Mining Barbados, Inc., a wholly-owned subsidiary of Gold Reserve Inc.

Deposit Type

  • Porphyry


Summary:

BRISAS
A possible deposit analogy is of a copper porphyry forming over a magmatic source (yet to be discovered) that was very rich in boron. A peraluminous granite might fit the boron requirements and a sufficient volume of basaltic/andesitic rock could provide the copper. Thin lenses of high Cu and Mo extending away along bedding/foliation planes could be the result of periodic high confining pressures within the Blue Whale that forced mineralizing fluids outward along these planes. The fluids replaced crystals and lithic fragments, evidence of which can be viewed in drill core.

There are four distinct types of gold and copper mineralization present at Brisas, defined by geometry, associated minerals, and the gold-copper ratio. These zones are the Blue Whale body, disseminated gold + pyrite ± copper, disseminated high copper, and shear-hosted gold. Only the first three types are encountered within the proposed pit geometry.

The Blue Whale mineralized body is a discrete, sharply bounded, flattened, cigar-shaped feature that trends more or less parallel to the local schistosity and plunges approximately 35° southwest.

Mineralogically, the Blue Whale is a sericite- tourmaline-pyrite-chalcopyrite-quartz schist, with a smaller volume of quartz-tourmaline-sulphide breccia.

The bulk of mineralization occurs in disseminated, coalescing, lensoid bodies, and high in gold and in most cases low in copper. These bodies lie almost exclusively in the lapilli-rich, rapidly alternating sequence of tuffaceous units and are clearly aligned along foliation. Together, these lenses form a generally well defined mineralized band, which mimics the dip of the foliation/bedding and remains open at depth. It remains at a similar thickness from the northern concession boundary for a distance of 1.4 km south, after which, it tapers rapidly. Alteration minerals characteristic of these lenses are epidote, chlorite, secondary biotite, and sericite.

Stratiform lenses of high copper with or without high gold underlie the gold+pyrite lenses described above. These lenses outcrop in the northern part of the deposit, and plunge to the south in a manner similar to the Blue Whale and high gold/low copper lenses but with variable dips.

Shear-hosted gold occurrences exist in the southern part of the concession, running parallel to the foliation as with mineralization further north. Stratigraphically, they occur above the large disseminated lenses previously described. The gold and copper grades are erratic and discontinuous.

CRISTINAS
In terms of classification, Cristinas has been assigned to shear zone-hosted systems by some geologists, and to a porphyry association by others; however, several key elements of the Cristinas deposit must be satisfied in any attempt to classify the deposit.

The main two styles of mineralization present at Cristinas are:
1. Stratiform mineralization at Conductora, Morrocoy, and Cordova.
2. Hydrothermal breccia-hosted mineralization at Mesones-Sofia.

The Conductora (including Cuatro Muertos and Potaso), Morrocoy, and Cordova areas contain over 95% of the gold resource at Cristinas.

Mineralization occurs in a greater than three- kilometre long, north-trending zone that dips moderately (30° to 40°) to the west, sub-parallel to the volcanic stratigraphy and to the pervasive (S1) cleavage. Gold mineralization is associated with a sulphide assemblage that consists essentially of pyrite and chalcopyrite.

Mineralization in Mesones-Sofia is concentrated in the quartz-tourmaline-sulphide-calcite vein breccias and extends laterally into the adjacent country rocks. The breccias are sufficiently closely spaced that the country rock between them also constitutes ore in the central part of Mesones-Sofia. Grades in the country rock on the periphery of the system decrease as the distance between the breccias increase.

Discrete auriferous quartz veins are located adjacent to the Cristinas deposit. Such veins include the Los Rojas and Albino veins that lie approximately one kilometre to the east of the Conductora area, and the Hofman vein, which lies about one kilometre to the west of the Cordova area. These veins consist of quartz with gold mineralization associated with pyrite (there is no appreciable chalcopyrite). The veins have chlorite selvages about 50 cm wide. Although gold mineralization in these veins does not constitute part of the Cristinas resource, they are considered to be genetically related, and peripheral, to the Cristinas deposit.


Mining Methods

  • Truck & Shovel / Loader


Summary:

The Siembra Minera Project is an open-pit gold- copper mining project. The mine will be a conventional truck and shovel open pit mining operation, which will utilize hydraulic shovels and 236-tonne trucks as the primary mining equipment. Ancillary activities will include, however not be limited to, road maintenance, road dust control, site dewatering, dump and stockpile maintenance, and grade control.

Brisas inter-ramp pit slopes based on Vector (2007) range from 22° to 30° in saprolite, 36.2° to 46.6° in the east wall, and 46.6° to 52° in the west wall. Cristinas pit slopes based on SNCLavalin (2005) are 31° for saprolite, 45° for east wall, and 50° to 55° for hard rock on the west and south wall.

The pit slopes used for RPA’s pit optimization were 36° for oxide saprolite, 46° for sulphide saprolite, and 48° for hard rock for the entire deposit.

The resource pit is approximately 6,000 m long and 1,900 m wide with a maximum depth of approximately 700 m. The total material including waste is 5,910 million tonnes. The pit slope on the east wall follows the mineralization with slopes from 36° to 38°; the west wall final pit has overall pit slopes ranging from 48° to 50°.


Crushing and Grinding
Flow Sheet: Source
Crusher / Mill TypeModelSizePowerQuantity
Gyratory crusher 2
Roll crusher 1
SAG mill 4
Ball mill 9

Summary:

The overall Project contemplates two plants: a smaller 15,000 tonne per day ("tpd") cyanidation plant (the "Small Plant") and a larger 140,000 tpd flotation plant (the "Large Plant"). The Small Plant is designed to recover gold from oxide saprolite and sulfide saprolite that contains low concentrations of copper and the Large Plant is designed to process hard rock material containing higher concentrations of copper as well as gold. The overall mine life is estimated to be 45 years after achieving commercial production of the Large Plant.

The Project is expected to begin with the Small Plant, which is estimated to take two years for detail design and construction while providing a platform for establishing the Project's operations and management group in advance of the Large Plant operation.


Processing

  • Gravity separation
  • Flotation
  • Agitated tank (VAT) leaching
  • Carbon in leach (CIL)
  • Carbon in pulp (CIP)
  • AARL elution
  • Carbon adsorption-desorption-recovery (ADR)
  • Solvent Extraction & Electrowinning
  • Cyanide (reagent)

Flow Sheet: Subscription required

Summary:

The overall Project contemplates two plants: a smaller 15,000 tonne per day ("tpd") cyanidation plant (the "Small Plant") and a larger 140,000 tpd flotation plant (the "Large Plant"). The Small Plant is designed to recover gold from oxide saprolite and sulfide saprolite that contains low concentrations of copper and the Large Plant is designed to process hard rock material containing higher concentrations of copper as well as gold. The overall mine life is estimated to be 45 years after achieving commercial production of the Large Plant.

The Project is expected to begin with the Small Plant, which is estimated to take two years for detail design and construction while providing a platform for establishing the Project's operations and management group in advance of the Large Plant operation.

Recoveries & Grades:

CommodityParameterAvg. LOM
Gold Recovery Rate, % 83.9
Gold Head Grade, g/t 0.7
Copper Recovery Rate, % 84
Copper Head Grade, % 0.09
Silver Recovery Rate, % 53
Silver Head Grade, g/t 0.5

Projected Production:

CommodityProductUnitsAvg. AnnualLOM
Gold Payable metal koz 83637,639
Gold Metal in conc./ doré koz 38,127
Copper Payable metal M lbs  ......  Subscription required  ......  Subscription required
Copper Metal in concentrate M lbs  ......  Subscription required
Silver Payable metal koz  ......  Subscription required  ......  Subscription required
Silver Metal in conc./ doré koz  ......  Subscription required

Operational Metrics:

Metrics
Stripping / waste ratio 1.16 *
Daily mining capacity 400,000 t *
Waste tonnes, LOM 2,320,350 kt *
Ore tonnes mined, LOM 2,004,741 kt *
Total tonnes mined, LOM 4,325,091 kt *
Daily processing capacity 182,000 t *
Tonnes processed, LOM 2,004,741 kt *
* According to 2018 study.

Reserves at December 31, 2017:
Mineral Resources are estimated at an NSR cut-off value of US$7.20 per tonne for oxide-saprolite material and US$5.00 per tonne for sulphide-saprolite and fresh rock material.

CategoryTonnage CommodityGradeContained Metal
Measured 10 Mt Gold 1.02 g/t 318 koz
Measured 10 Mt Copper 0.18 % 38 M lbs
Indicated 1,174 Mt Gold 0.7 g/t 26,504 koz
Indicated 1,174 Mt Copper 0.1 % 2,649 M lbs
Measured & Indicated 1,184 Mt Gold 0.7 g/t 26,822 koz
Measured & Indicated 1,184 Mt Copper 0.1 % 2,687 M lbs
Inferred 1,291 Mt Gold 0.61 g/t 25,389 koz
Inferred 1,291 Mt Copper 0.08 % 2,300 M lbs

Commodity Production Costs:

CommodityUnitsAverage
Credits (by-product) Gold USD -262 / oz *
Site cash costs (produced) Gold USD 495 / oz *
Cash costs Gold USD 542 / oz *
Cash costs Gold USD 280 / oz *†
Total cash costs Gold USD 428 / oz *†
All-in sustaining costs (AISC) Gold USD 483 / oz *†
Assumed price Copper USD 3 / lb *
Assumed price Silver USD 17 / oz *
Assumed price Gold USD 1,300 / oz *
* According to 2018 study / presentation.
† Net of By-Product.

Operating Costs:

Units2018
OP mining costs ($/t mined) USD 1.36 *
OP mining costs ($/t milled) USD  ......  Subscription required
Direct operating costs ($/t milled) USD  ......  Subscription required
Processing costs ($/t milled) USD  ......  Subscription required
Total operating costs ($/t milled) USD  ......  Subscription required
* According to 2018 study.
Subscription required - Subscription is required.

2018 Study Costs and Valuation Metrics :

MetricsUnitsLOM Total
Initial CapEx $M USD  ......  Subscription required
Sustaining CapEx $M USD  ......  Subscription required
Closure costs $M USD  ......  Subscription required
Total CapEx $M USD  ......  Subscription required
OP OpEx $M USD  ......  Subscription required
Processing OpEx $M USD 9,881
G&A costs $M USD 2,654
Total OpEx $M USD  ......  Subscription required
Income Taxes $M USD  ......  Subscription required
Total Taxes $M USD  ......  Subscription required
Gross revenue (LOM) $M USD  ......  Subscription required
EBITDA (LOM) $M USD  ......  Subscription required
Pre-tax Cash Flow (LOM) $M USD  ......  Subscription required
After-tax Cash Flow (LOM) $M USD  ......  Subscription required
Pre-tax NPV @ 5% $M USD  ......  Subscription required
Pre-tax NPV @ 10% $M USD  ......  Subscription required
After-tax NPV @ 5% $M USD  ......  Subscription required
After-tax NPV @ 10% $M USD  ......  Subscription required
Pre-tax IRR, %  ......  Subscription required
After-tax IRR, %  ......  Subscription required
Pre-tax payback period, years  ......  Subscription required
After-tax payback period, years  ......  Subscription required
Subscription required - Subscription is required.

Proposed Heavy Mobile Equipment as of March 16, 2018:
HME TypeModelSizeQuantity
Dozer (crawler) ....................... Subscription required ....................... Subscription required
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Subscription required - Subscription is required.

Mine Management:

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Mar 16, 2018
....................... Subscription required ....................... Subscription required Subscription required Mar 16, 2018
Subscription required - Subscription is required.


Corporate Filings & Presentations:

DocumentYear
................................... Subscription required 2019
Preliminary Economic Assessment 2018
Press Release 2018
Year-end Mineral Reserves 2008
Subscription required - Subscription is required.

News:

NewsDate
Gold Reserve Provides Positive PEA on Siembra Minera Project March 20, 2018

Subscription required - Subscription is required.

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