La India achieved commercial production on February 1, 2014, and has a mine life of approximately five more years. Our Pinos Altos and Creston Mascota mine complex is approximately 70 km southeast of La India, providing operating synergy between the two properties.
2015 production and costs
104,362 oz, $436/oz gold
The La India mine is located approximately 200 km east of Hermosillo in Sonora, Mexico. The 627-square km property includes the La India mine site, the Tarachi gold resource and several other prospective exploration targets, situated in the prolific Mulatos gold belt. The La India mine hosts proven and probable reserves of 0.9 million ounces of gold contained within 30.0 million tonnes of ore grading 0.90 g/t gold. The mine has now achieved its design capacity, with 100,000 ounces of gold production expected in 2016, and an average annual production rate of 110,000 ounces gold from 2017 to 2018.
The La India mine lies within an extensive ancient volcanic field. It is in an area dominated by outcrops of volcanic tuffs from different explosive volcanic events that were affected by large-scale north-northwest-striking faults and intruded by granodiorite and diorite stocks. Canyons cut through the uppermost layers to expose the Lower Series volcanic strata.
La India lies in a large area of intrusion-related alteration dominated by high-sulphidation epithermal-style gold mineralization. The gold mineralization is confined to zones of argillitic alteration originally containing sulphides and subsequently oxidized. All of La India’s reserves are in oxidized material, amenable to heap leaching. The gold system at Tarachi is best classified as a wallrock gold porphyry deposit, comprising sheeted veins that deposited gold within the wallrock outside the source dacite porphyry intrusions, suggesting that it has the potential to grow into a much larger deposit.
The La India mine is a collection of deposits grouped into three open pits – North, La India (Central) and Main – that are being mined over an estimated seven-year life, providing ore for a heap leach pad located just west of the North pit. The mining rate is expected to be approximately 16,000 tonnes/day with a stripping ratio of approximately 1:1.
La India’s processing flow includes a three-stage crushing process followed by a heap leach operation. The leach pad has a capacity of up to 50 million dry tonnes, reaching an ultimate height of approximately 113 metres. Cyanide leach solution percolates through the heap to the lined solution-collection ditch that routes it to a double-lined pregnant collection pond. A zero discharge water balance is maintained at the heap leach facilities. The gold adsorption facility (ADR plant) consists of two parallel trains of five 3.5-tonne carbon adsorption columns and a Zadra strip with electrowinning. Gold-silver doré bars are produced in the refinery. The plant is designed to process leach flows from up to 6.0 million dry tonnes of ore per year (16,438 tonnes/day). Gold recovery is estimated at 80% with a 90-day leach time.
The 2015 exploration program resulted in a 28% increase of gold in mineral reserves, and a 21% increase of gold in measured and indicated mineral resources. We are looking at near-pit potential with a goal of further expanding the mineral reserves at the Main and North Zones, and will consider opportunities to increase production at La India based on the success of that program.
The Tarachi property is part of a large land package that surrounds Agnico’s La India mine in the Mulatos district of Sonora, Mexico. Tarachi is a large low-grade gold porphyry deposit with satellite epithermal mineral occurrences discovered in 2010.