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Santa Luz Gold Mine
Producing gold in Brazil
Santa Luz is an open-pit mine with resin-in-leach processing that achieved commercial production effective October 1, 2022.
~57,200 oz gold
$1,775-$1,950 per oz AISC
1,075 Koz @ 1.34 g/t gold
900 Koz @ 1.69 g/t gold
Mining and processing
Open pit / RIL plant
Estimated mine life
~9 years with existing reserves
Santa Luz is located within the Maria Preta mining district in Bahia State, Brazil, 35 km north of the town of Santa Luz, 240 km northwest of the state capital, Salvador, 55 km northwest of Equinox Gold’s Fazenda mine, and 163 km from Yamana’s Jacobina gold mine.
Santa Luz is Equinox Gold’s newest mine and its second successful mine build in Brazil. Equinox Gold assumed ownership of Santa Luz in March 2020 through its acquisition of Leagold Mining. Equinox Gold updated the Santa Luz feasibility study, commenced re-construction in November 2020 and poured first gold in March 2022 from the mine’s new resin-in-leach (RIL) circuit. Construction was completed with no lost-time injuries and commercial production was declared effective October 1, 2022.
Santa Luz operated briefly from 2013-2014 but was placed on care and maintenance due to poor recoveries from its carbon-in-leach plant. Subsequent metallurgical testing programs, including the operation of an on-site pilot-scale plant, demonstrated that RIL is a better method of gold recovery for Santa Luz’s carbonaceous ores. Construction activities to restart the mine included refurbishing existing infrastructure, retrofitting the plant to use resin-in-leach processing, installing additional grinding power and increasing the storage capacities of the existing tailings and water storage facilities.
The RIL circuit is operating as planned and recovery rates are higher than achieved with the historical carbon-in-leach circuit. Challenges remain, however, and the Company continues to focus on implementing process improvements to optimize recoveries. Recoveries have been improving and are expected to average around 70% for 2023.
Production at Santa Luz for 2023 is forecast at 60,000 to 70,000 ounces of gold with all-in sustaining costs between $1,775 to $1,950 per ounce of gold sold. Sustaining capital of $17 million is primarily for a tailings facility raise and open-pit waste stripping, as well as installation of a pebble crusher. Non-sustaining capital of $2 million is for exploration.
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Mining and Processing
Santa Luz is a contractor-operated conventional truck and shovel open pit mining operation with a strip ratio of approximately 4.7:1 (waste:ore). All material from the pit is stockpiled and separated by ore type. The material is then blended from these stockpiles to provide feed to the primary crusher. The RIL processing circuit is designed for throughput of 7,400 tonnes per day.
The ore blend is a critical factor to ensure optimal metallurgical recovery, and the stockpiles are required to keep sufficient ore volumes and grades appropriate for blending. The Santa Luz deposit consists of essentially two ore types: carbonaceous and dacitic. The carbonaceous ore comprises approximately 52% of the deposit and exhibits pregnant solution robbing characteristics when subjected to conventional cyanide leaching. Resin-in-leach processing resolves this issue if the average total organic carbon (TOC) content of the blended carbonaceous and dacitic ores is kept to 0.6% or lower.
While the life-of-mine plan outlined in the 2020 feasibility study shows recoveries averaging 84%, the cost-benefit trade-off of maximizing recoveries versus the cost of handling ore to achieve the target TOC blend may result in lower long-term recoveries. The Company continues to optimize the process with the objective of maximizing recoveries and gold production.
Exploration and Geology
Santa Luz is hosted within the Rio Itapicurú Greenstone Belt (RIGB), which comprises the northeastern portion of the São Francisco Craton which was formed through the collision of several small Archean cratons. The north-south trending belt extends for approximately 100 km and ranges in width from 30 km to 50 km. The belt comprises three domains (mafic volcanic, felsic volcanic, and sedimentary), all intruded by later granitioid bodies. Gold deposits and prospects in the Santa Luz area occur in shear and breccia zones at, or proximal to, the faulted contact of the volcanic and sedimentary domains in a continuous, north and locally northeasterly striking, mineralized zone. Mineralization is associated with quartz‐carbonate‐sulphide veining and breccia fillings. Host rocks include a variety of epizonal dioritic and dacitic intrusive rocks, sedimentary rocks, and felsic to intermediate volcanic rocks.
The 2020 Santa Luz feasibility study included a preliminary economic assessment (PEA) of the potential to exploit Mineral Resources below the C1 open pit using underground mining methods. The C1 Underground project could be operated concurrently with the existing open pit mine and has the potential to deliver an additional estimated 511,000 oz of gold over an initial 9.5 year mine life. The C1 Underground resources are a proximal down-dip extension of the Mineral Resource exploited by the C1 open pit. If Equinox Gold elects to develop the C1 Underground, development of the main decline would take approximately two years. The preliminary economic analysis of the C1 Underground is based, in part, on Inferred Resources, and is preliminary in nature. There is no certainty that the results contemplated in the PEA will be realized. Equinox Gold believes there is the potential for significant additional Mineral Resources to be delineated in down-dip and lateral extensions of the C1 Underground Mineral Resource.
Ongoing exploration in the Bahia District along the 70-km long greenstone belt that hosts Equinox Gold’s Santa Luz and Fazenda mines has identified the potential to establish a mining district with the opportunity to truck mineralization to either Fazenda or Santa Luz for processing, based on the ore’s metallurgical characteristics.