El Compas gold-silver project started production in March 2019. Image courtesy of Endeavour Silver.
The El Compas gold-silver mine is located 1km south of the Zacatecas city in Mexico. Image courtesy of Eneas De Troya.
El Compas is expected to produce 135,000oz of silver and 11,500oz of gold a year. Image courtesy of Романвер.

El Compas gold-silver project comprises 28 mining concessions covering 4,217ha in the southern part of Zacatecas, one of the biggest historic silver mining districts of Mexico.

Owned by Endeavour Silver, the El Compas project is focused on two high-grade gold-silver vein structures namely El Compas and El Orito.

The preliminary economic assessment (PEA) for the project was completed in May 2017 and construction was started in the same year, while commercial production was started in March 2019.

The project is expected to produce 135,000 ounces (oz) of silver, 11,500oz of gold, and one million ounce (Moz) of silver-equivalent a year, over its initial five years of mine life.

The project has huge potential for further development with ten untested vein targets at El Compas and several known veins at newly acquired adjacent properties of Calicanto and Veta Grande.

El Compas gold-silver project development details

Endeavour Silver acquired Oro Silver Resources, a subsidiary of Canarc Resource, in May 2016 to become the owner of El Compas mine located 1km south of Zacatecas city. It also holds a five-year renewable lease on the 500 tonnes per day (tpd) La Plata ore processing plant located 20km south from the mine site, as a result of the acquisition.

Endeavour Silver developed the mechanised, underground ramp access to target the El Compas and El Orito veins for production and  refurbished a 500tpd plant for initial 325tpd operation.

El Compas geology and mineralisation

El Compas is situated within the Zacatecas mining district that lies between the Sierra Madre Occidental and the Mesa Central physiographic provinces of north-central Mexico.

The mining district comprises tertiary-aged epithermal vein deposits containing silver, gold as well as base metals such as copper, lead, and zinc.

Striking mostly in north and north-west directions, the low-sulphidation epithermal vein deposits at El Compas and El Orito are hosted in volcanic and sedimentary rocks of the Chilitos and La Virgen formations.

Silver and gold resources at El Compas

The proven and probable ore reserves of the El Compas project were estimated to be 67,000t grading 90g/t of Ag and 3.99g/t of Au, as of December 2018.

The  project was also estimated contain 80,000t of measured and indicated resources grading 80g/t of Ag and 4.5g/t of Au.

Mining and ore processing

El Compas is an underground, mechanised long-hole and cut-and-fill mining operation with ramp access.

A 535m-long trackless haulage ramp provides primary access to the deposit from the portal at 2,265m elevation. A 407m-long haulage ramp connects the El Compas and El Orito Veins.

A total of 48 three-meter-high lifts are planned for  the El Compas Vein, while 38 three-metre-high lifts will be located at the El Orito Vein.

Micro scooptrams and hand-held pneumatic drills are used to extract ore from the deposits. The feed from the El Compas mine is trucked to the La Plata processing facility, where it undergoes three-stage crushing, grinding, hydrocyclone, gravity concentration, and floatation for the production of gold-silver concentrates.

The concentrates are further thickened and pressure-filtered before being bagged for shipment.

Contractors involved in El Compas gold-silver project

Smith Foster + Associates prepared the preliminary economic assessment (PEA) for the project in 2017.

P&E Mining Consultants undertook the mineral resource estimate and provided mining cost estimates for the project.

Knight Piésold provided the tailings and water management concepts for the project.