Brazil

Volta Grande Project

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Overview

Mine TypeOpen Pit
StagePermitting
Commodities
  • Gold
Mining Method
  • Truck & Shovel / Loader
Mine Life17 years (as of Jan 1, 2015)
ShapshotBelo Sun is progressing the Volta Grande Gold Projec (PVG) towards construction and has successfully completed its EIA, its LP, its LI, conducted basic engineering, and recently completed its required ECI (Indigenous Study).

Owners

SourceSource
CompanyInterestOwnership
Belo Sun Mining Corp. 100 % Indirect
Belo Sun Mining Corp. owns 100% interest in the Volta Grande Gold project through its wholly owned subsidiary, Belo Sun Mineração Ltda.

Deposit type

  • Hydrothermal
  • Saprolite
  • Vein / narrow vein

Summary:

The Volta Grande gold project contains two target areas named the North and South blocks; the former contains four large mineralized areas: (1) the Ouro Verde area in the northwestern part of the North Block, (2) the Grota Seca area, (3) the Junction area that connects Grota Seca and Ouro Verde and (4) the Greia area north of Grota Seca. The South Block comprises three target areas: (1) Pequi in the northern part of the South Block, (2) Grande in the southern part of the South Block, and (3) Itatá in the southeastern part of the South Block. The North Block as well as the South Block include old and new garimpeiros workings.

In the central part of the North Block, a north-northwest–trending lineament separates the southeastern mineralized zones of the Grota Seca from the northwestern zones at Ouro Verde and coincides largely with the Junction area. This lineament is parallel to other regional lineaments with similar orientation.

There is a complicated contact relationship between auriferous bedrock and the overlying saprolitic material. At Grota Seca, near recent garimpeiros workings, almost fresh diorite is in sharp contact with saprolitic material, which is at least 8 metres thick. This juxtaposition indicates that the saprolite is not made up of regular regolithic material developed on top of bedrock, but is transported by faulting parallel to the major shear zone that hosts the gold mineralization.

There are a number of north-northwest–trending regional structures present in the area. One of these is parallel to the segment of the Xingu River flowing from Altamira to the Volta Grande gold project exploration camp. Other structures with similar orientation are present in the area west of Ouro Verde, one of which cuts a northeast trending structure.

In the South Block, mineralization is primarily hosted in granodiorite; however, the Pequi target is located at the northern contact of the granodiorite body to an amphibolite body to the north. While mineralization in the North Block is controlled by northwest-striking structural features, mineralization in the South Block appears to occur primarily where northwest-striking structures intersect with north-striking faults. Drilling as well as exposure in a large pit dug by garimpeiros shows two distinct mineralization directions. The first is steep, subvertical with a north-east strike. The second direction is shallow, dipping approximately 20 degrees to the southwest. These two directions can be seen in core as well and strongly influenced the modelling of the boundaries of the gold mineralization for the Grande deposit, which changed significantly from an earlier model. SRK expects that future drilling will refine further the understanding of the geology of the South Block.

There are two types of gold mineralization at Project - primary gold in intrusive rock and secondary gold in saprolitic rock. Both types of gold mineralization occur within a major shear zone. In general, the gold mineralization in bedrock occurs in zones of intense hydrothermal replacement and is associated with up to approximately five percent sulphides (pyrite and / or arsenopyrite) at Grota Seca and Ouro Verde. Specifically, mineralization styles are:

- Intense silicification with with up to five percent fine-grained sulphide (predominantly arsenopyrite) within strongly sheared diorite, such as at the Grota Seca area;
- Weak to moderate silicification in diorite with minor sulphides (mainly pyrite), such as at the Ouro Verde area; and
- Intensive silification overprinted by sulphide alteration (pyrite) and potassium alteration (sericitization and potassic feldspar formation), such as in the South Block area.

In all cases, the distribution of alteration assemblages and the replacement textures suggest evolution of fluid-rock alteration. The initial hydrothermal alteration involved silicification (quartz flooding) of the host diorite. Subsequent alteration included replacement by pyrite and/or arsenopyrite, followed by potassium feldspar alteration and sericitization.

Finally, all of the rocks in the area were subjected to carbonate alteration. This alteration is evidenced by the presence of numerous calcite veinlets in the diorite as well as in the metavolcanic rock.

Gold deposition is interpreted to be related to changes in local chemical conditions of mineralizing fluids in response to progressive fluid-rock interaction, which triggered sulphide precipitation. The sulphide content of the gold mineralization is low.

Primary Gold Mineralization
Gold mineralization at the Project occurs primarily in intrusive rock, while subordinate mineralization occurs in saprolitic rock. Primary gold mineralization is associated with altered diorite within a 300 m wide alteration zone, which straddles the contact zone between the intrusive and the metasedimentary rock. Gold occurs in a stack of mineralized zones ranging in size from strike trends over 1 km long, depths from surface to approximately 400 m, with true thickness ranging up to 50 m.

The dip of the mineralized zones is generally moderate to steep (50° to 85°) to the south. Two large mineralized areas occur in the North Block: Ouro Verde in the northwestern portion of the block and Grota Seca in the southern portion.

Mineralization in the Ouro Verde area extends for approximately 1,100 m along an approximate northeast-southwest strike and extends to a vertical depth of 540 m below surface.

Mineralization in the Grota Seca area extends for approximately 2,900 m along a west to north-west trend and extends to a vertical depth of 400 m below surface.

Saprolite Gold Mineralization
Surficial weathering has resulted in an extensive saprolitic profile overlying the primary mineralization at the Project. In general, the thickness of the saprolitic material ranges from 3 m to 20 m. Locally the thickness can reach up to 45 m, as in the Ouro Verde area. Occasional outcrops of saprolitic material occur in the Project area.

Overburden thickness ranges from 3 m to more than 10 m. Typical lateritic and saprolitic profiles with gold mineralization are observed in the many small open pits as well as in diamond drill core.

The lateral transport of the gold in the surficial environment is caused by frequent changes in the water table in the rock and surficial alteration of the sulphides as well as the gangue minerals in the rock.

In general, the average grade of the lateritic material is lower than the saprolitic material, which is also lower grade than the primary mineralization underlying the saprolite. Occasionally, however, the saprolite may also contain high-grade intersections. These occurrences are generally due to mineralized quartz vein material, which is more resistant than the enclosing saprolitic rock; the quartz becomes enriched in the saprolite leading to increased gold values.

Typically, gold anomalies in laterite / saprolite extend beyond underlying mineralization in hard rock; however, in the Project area, the saprolitic zone gold mineralization does not appear to be much larger than the underlying primary mineralization in bedrock.

Reserves

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Mining Methods

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Comminution

Crushers and Mills

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Processing

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Production

CommodityProductUnitsAvg. AnnualLOM
Gold Payable metal koz 3,524
Gold Metal in doré koz 2053,527

Operational metrics

Metrics
Daily ore mining rate 20,000 t *
Daily milling rate 20,000 t *
Annual milling capacity 7 Mt *
Stripping / waste ratio 4.3 *
Waste tonnes, LOM 503,824 kt *
Ore tonnes mined, LOM 117,943 kt *
Total tonnes mined, LOM 667,955 kt *
Tonnes milled, LOM 115,969 kt *
* According to 2015 study.

Production Costs

CommodityUnitsEstimated
Cash costs Gold USD 000
Total cash costs Gold USD 000
All-in sustaining costs (AISC) Gold USD 000
Assumed price Gold USD 0000
* According to 2015 study / presentation.

Operating Costs

Currency2023
OP mining costs ($/t mined) USD 10.6 *  USD
Processing costs ($/t milled) USD  ....  Subscribe
Total operating costs ($/t milled) USD  ....  Subscribe
* According to 2015 study.

Project Costs

MetricsUnitsLOM Total
Initial CapEx $M USD  ......  Subscribe
Sustaining CapEx $M USD  ......  Subscribe
Closure costs $M USD  ......  Subscribe
Total CapEx $M USD  ......  Subscribe
Processing OpEx $M USD 841
Net revenue (LOM) $M USD  ......  Subscribe
After-tax Cash Flow (LOM) $M USD  ......  Subscribe
Pre-tax NPV @ 5% $M USD  ......  Subscribe
After-tax NPV @ 5% $M USD  ......  Subscribe
Pre-tax IRR, %  ......  Subscribe
After-tax IRR, %  ......  Subscribe
Pre-tax payback period, years  ......  Subscribe
After-tax payback period, years  ......  Subscribe

Heavy Mobile Equipment

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Personnel

Mine Management

Source Source
Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Mar 30, 2015
....................... Subscription required ....................... Subscription required Subscription required Mar 30, 2015
....................... Subscription required ....................... Subscription required Subscription required Jan 8, 2024

Total WorkforceYear
Subscription required 2015

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