Brazil

Riacho dos Machados (RDM) Mine

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Categories

Overview

Mine TypeOpen Pit
StatusActive
Commodities
  • Gold
Mining Method
  • Truck & Shovel / Loader
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SnapshotRDM is a conventional open-pit mine with a carbon-in-leach plant.

In July 2022 the company decided to focus on processing low-grade stockpiles and owner mining to reduce costs while the tailings storage facility raise is underway.

2023 plan: Resumed owner mining of open pits, completing TSF raise and permitting for filtered tailings facility.

Owners

SourceSource
CompanyInterestOwnership
Mineração Riacho Dos Machados Ltda. (operator) 100 % Direct
Equinox Gold  Corp. 100 % Indirect
Riacho dos Machados (RDM) is held under the name of Mineração Riacho dos Machados (MRDM), an indirect wholly owned subsidiary of Equinox Gold, incorporated under the laws of Brazil.

Contractors

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Deposit type

  • Mesothermal
  • Orogenic
  • Vein / narrow vein

Summary:

The Riacho dos Machados gold deposit is considered to be a classic mesothermal orogenic gold deposit in a sheared and deformed Archean to Proterozoic age greenstone belt sequence. It is comprised of metamorphosed volcanic-sedimentary rock units intruded by slightly younger post-tectonic igneous bodies.

The principal host for the gold mineralization is the quartz-muscovite schist of the RMG. The mineralization occurs in a belt of hydrothermally altered rock developed along a district-scale shear zone that extends almost 30 km along a N20°E strike direction and dips 40° to 45° east. The mineralization has a typical amphibolite facies mineral association which is progressively altered to greenschist facies assemblage. The gold mineralization occurs as “stacked” tabular horizons that are mostly concordant with the principal rock foliation (shear zone). These tabular zones typically consist of a main zone which may be sided by a thinner footwall or hanging wall zones, separated by three meters to ten meters of unmineralized rock. Continuity along strike and at depth is good with gold mineralization occurring continuously over a 2,000 m strike length and up to 1,000 m down dip.

Gold grades in the mineralized zone are closely related to sulphide content, especially arsenopyrite. Gold occurs as microscopic native-gold grains typically finer than 400 mesh (37 µm). The gold grains occur interstitial to quartz grains, muscovite grains, and sulphide grains, and also as inclusions in arsenopyrite, and less commonly in pyrrhotite, quartz-veinlets, tourmaline, and pyrite.

The following minerals and features, listed from high to low importance, are noted as indicators of gold mineralization:

-Arsenopyrite (both anhedral and euhedral needles);
- Pyrrhotite;
- Abundant quartz veinlets (sheared into foliation plane);
- Pyrite;
- Crenulation folding;
- Tourmaline veins (fine-grained massive intergrown).

The arsenic content of the mineralization is relatively high, with an average of approximately 4,000 ppm for samples greater than 1.0 g/t Au. Silver content is very low, with the average Ag/Au ratio of 0.5:1.0 for samples with a gold concentration of greater than 1.0 g/t. Antimony, copper, lead, and zinc are not commonly anomalous.

The gold mineralization is closely related to the structural fabric. The mineralizing fluid was probably channelled upward in the thrust-related shear zones with minor or local lateral escape into intersecting shear zones. Brittle deformation at the RDM deposit is limited to poorly defined crossfaults that may have anomalous geochemistry but do not host gold mineralization.

The area presents the occurrence of graphite, which influences the metallurgical behaviour of the ore. Graphite occurs in shear zones filling intrafolial planes, ranging from 2 to 20 cm thick, and in the form of boulders, with lenticular geometry or symmetrical boudins associated with quartz veins, with thicknesses of up to 1.5 m. They have dark grey and black coloration and low hardness, and due to graphite's lubricating characteristics, act as zones of geomechanical weakness. Graphite is in nonmineralized areas, associated with domains of marginal or waste contents, or in mineralized areas with the presence of high sulphidation.

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

In 2022 RDM switched to processing low-grade stockpiles and owner mining to reduce costs.
CommodityUnits20232022202120202019201820172016
Gold koz  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe63574348
All production numbers are expressed as metal in doré. ^ Guidance / Forecast.

Operational metrics

Metrics2022202120202019201820172016
Stripping / waste ratio  ....  Subscribe  ....  Subscribe
Ore tonnes mined  ....  Subscribe  ....  Subscribe  ....  Subscribe2,458,895 t1,390 kt1,723,506 t1,054,574 t
Waste  ....  Subscribe  ....  Subscribe  ....  Subscribe
Total tonnes mined  ....  Subscribe  ....  Subscribe  ....  Subscribe
Tonnes processed  ....  Subscribe  ....  Subscribe  ....  Subscribe2,548,393 t1,958 kt1,253,329 t850,029 t
Daily processing capacity  ....  Subscribe  ....  Subscribe  ....  Subscribe7,000 t7,000 t
Annual processing capacity  ....  Subscribe  ....  Subscribe  ....  Subscribe2.55 Mt2.55 Mt

Production Costs

CommodityUnits202320222021202020182017
Cash costs (sold) Gold USD  ....  Subscribe  ....  Subscribe 946 / oz  
Cash costs Gold USD 814 / oz  
Cash costs (sold) Gold USD  ....  Subscribe  ....  Subscribe
All-in sustaining costs (sold) Gold USD  ....  Subscribe  ....  Subscribe 1,009 / oz  
All-in sustaining costs (AISC) Gold USD 989 / oz  
All-in sustaining costs (sold) Gold USD  ....  Subscribe  ....  Subscribe
^ Guidance / Forecast.
** Net of By-Product.

Operating Costs

Currency20222021202020192018
OP mining costs ($/t mined) USD 2.75  2.04  1.76  2.66  2.07  
OP mining costs ($/t milled) USD  ....  Subscribe  ....  Subscribe  ....  Subscribe
Processing costs ($/t milled) USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
G&A ($/t milled) USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe
Total operating costs ($/t milled) USD  ....  Subscribe  ....  Subscribe  ....  Subscribe

Financials

Units2023202220212020
Capital expenditures (planned) M USD  ....  Subscribe
Sustaining costs M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe
Capital expenditures M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe
Revenue M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe
Operating Income M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe

Heavy Mobile Equipment

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Personnel

Mine Management

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Mar 8, 2023
....................... Subscription required ....................... Subscription required Subscription required Mar 4, 2023
....................... Subscription required ....................... Subscription required Subscription required Mar 4, 2023

EmployeesContractorsTotal WorkforceYear
...... Subscription required ...... Subscription required ...... Subscription required 2020
...... Subscription required ...... Subscription required ...... Subscription required 2018

Aerial view:

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