The Guanajuato Mine Complex (GMC) is Great Panther's largest operation in Mexico and includes production from the San Ignacio Mine. For the purposes of resource estimation, the GMC also includes the El Horcon Project as, theoretically, any future production from El Horcon would be trucked to the Cata processing plant.
The GMC is located within the Guanajuato District – historically one of Mexico’s most prolific mining districts, with past production of over one billion ounces of silver and four million ounces of gold since the 16th century. The main Guanajuato mines, Cata processing plant and office facilities are situated within the capital city of Guanajuato, in Guanajuato State. These facilities have excellent infrastructure with access via city streets, and an international airport only 30 minutes away. The San Ignacio Mine lies approximately eight kilometres to the west and is accessed by a 22-kilometre paved road. Ore from San Ignacio is trucked to the Cata processing plant.
The GMC is an underground silver-gold operation that utilizes cut-and-fill mining methods. Numerous deposits are currently being mined with access provided via two shafts and two ramps. Ore is processed into a high quality, precious metal-rich concentrate for transportation to smelters overseas. The Cata processing plant, located near the central Cata shaft, consists of the following three segments:
- 3-stage crushing section, producing a (-¼ inch) fine ore mill feed;
- Grinding section, consisting of three ball mills operated in parallel and
- Conventional flotation circuit with a total capacity of 1,000 tonnes per day.
Most of the supplies and skilled labour required for mining and processing at the GMC are sourced from the cities of Guanajuato and Leon.
The GMC is 100% owned by Great Panther.
San Ignacio Mine
The San Ignacio Mine is located approximately eight kilometres west-northwest of the city of Guanajuato. Access to the property is provided via a 35-minute drive from the outskirts of the city (approximately 22 kilometres), mostly by paved road, through the towns of Santa Ana and Cristo del Rey. The San Ignacio Mine covers approximately four kilometres of strike length on the La Luz vein system, which is parallel to the principal Veta Madre structure that hosts Great Panther’s Guanajuato mines described above. Great Panther holds a 100% interest in the San Ignacio Property as it was acquired in 2005 as part of the Guanajuato package. Previous production had been halted in early 2001 due to low metal prices.
With Great Panther’s initial focus on the rehabilitation of the main Guanajuato mines, no work was conducted at San Ignacio until 2010, when the first exploration drilling discovered a new zone of silver-gold mineralization. Resources were quickly established and, with easy ramp access and no need for a stand-alone plant, underground development advanced rapidly, and the mine started commercial production in June 2014. Silver-gold mineralization at San Ignacio is similar to the epithermal veins at Guanajuato but with a higher gold-silver ratio.
The mine is currently operating at between 500 - 600 tonnes per day, thereby providing more than half of the daily mill feed for the Cata processing plant.
Guanajuato Mine Complex Operating Results
|Tonnes ore milled (000's)||222||268||310||321||320||301||188|
|Ore silver grade (g/t)||169||161||191||163||151||129||116|
|Ore gold grade (g/t)||2.3||2.03||2.35||2.43||2.41||2.27||2.26|
|Plant Silver Recovery (%)||89.7||89.2||88.5||87.9||89.2||87.9||84.7|
|Plant Gold Recovery (%)||84.1||90.8||90.2||86.4||86.9||87.1||85.2|
|Metal Production, (000's Ag eq oz)1||2,840||2,193||3,081||2,987||2,892||2,623||1,518|
|Silver Production, (000's oz)||1,711||1,239||1,708||1,473||1,387||1,097||591|
|Gold Production (oz)||15,714||15,906||21,126||21,626||21,501||19,073||11,588|
|Cash Cost / Ag oz (US$)1,2||10.42||11.12||5.77||0.85||4.32||10.23|
- Metal Production is expressed in terms of silver equivalent ounces, (Ag Eq oz), the formula for which depends on the gold and silver metal prices used in each year and hence are only indicative.
- Cash cost per ounce of silver is a non-IFRS measure used by the Company to manage and evaluate operating performance at each of the Company's mines. It comprises the cost of production, cost of concentrate transportation and the cost of smelter and refining charges, net of the by-product credits from the sale of gold. Refer to the "Non-IFRS Measures" in our MD&A.
- Includes production from San Ignacio.
The Guanajuato property is situated along the core of the prolific Veta Madre silver-gold structure. The world-class low sulphidation epithermal deposits are somewhat unique as they locally demonstrate a vertical depth extent of greater than 600m (this is rare for epithermal deposits and implies a long-lived mineralizing system).
To a certain degree, deep extensions of mineralization can be found by following known deposits down plunge. The Company has been successful at discovering new "blind" mineralized zones through systematic drilling and a continually improving understanding of the structural controls. In this way, Great Panther has been successful in replacing what it mines each year. Due to the complex nature of the ore, some zones are mined as they are found, without the need (or time) for detailed drilling. As such, approximately 30% of the production typically comes from zones outside of the official resource.
At the Guanajuato mines, underground exploration in 2017 was focused on the Cata, Los Pozos, Guanajuatito, San Cayetano, Santa Margarita and Valenciana mining areas. An underground drill program of approximately 14,000 metres is planned for 2018, which will continue to focus on increasing Mineral Resources in these same areas.
During 2017, exploration at the San Ignacio Mine consisted of both surface and underground drilling. This drilling resulted in the extension and continued delineation of the Melladito and Nombre de Dios zones and a significant increase in Measured and Indicated Mineral Resources. Plans for 2018 include 5,000 metres of surface exploration drilling designed to test the down dip extension of the main productive structures and along the Nombre de Dios structure, and 5,000 metres of underground delineation drilling to upgrade and expand resources in these areas.
When Great Panther acquired the Guanajuato Mines in 2005, there were no NI 43-101 compliant resources and the Company had to rehabilitate the mine in order to begin establishing a new resource base. Since then, seven NI 43-101 technical reports have been completed and filed.
A table of resources for the GMC can be found here
NI 43-101 Technical Report on the Guanajuato Mine Complex
Guanajuato, Mexico | August 31, 2017