Corani Silver-Lead-Zinc Project

The Corani silver-lead-zinc project is located in the district of Corani within the province of Carabaya, Puno, Peru. Bear Creek Mining, the project developer, obtained approval for the environmental and social impact assessment (ESIA) of the project from the Peruvian government in September 2013.

Construction permit for the project was approved in 2018 and the construction activities are expected to run until 2020. The project is expected to be commissioned in the first quarter of 2021.

With a total capital expenditure of $586m, the project is expected to recover 144 million ounces (Moz) of payable silver.

It is estimated to produce an annual average of 8Moz of silver and 150 million pounds (Mlbs) of combined lead and zinc through its anticipated mine life of 18 years.

Corani silver-lead-zinc project location, geology, and reserves

The Corani project site in southern Peru falls within the Cordillera Oriental of the Central Andes. It is located in the Andes Mountains at an elevation between 4,800 and 5,100 meters above sea level (masl) and extends in approximately 5,180ha.

The deposit is hosted within a stacked sequence of listric normal faults striking dominantly north to north-northwest with moderate to shallow westerly dips.

The project hosts tertiary volcanic rocks of the Quenemari Formation, with the most prominent ones being the crystal-lithic tuffs and andesite flows.

The primary mineralization is hosted in three zones namely Corani Main, Corani Minas, and Corani Este. Most of the mineralization is associated with iron and manganese oxides, barite, and silica.

Corani silver-lead-zinc project reserves

As of October 2017, the proven and probable mineral reserves of the Corani project were estimated at 139 million tonnes (Mt) grading 50.3g/t silver, 0.90% lead, and 0.59% zinc.

The project is estimated to contain 225Moz of silver, 2.75 billion pounds of lead, and 1.81 billion pounds of zinc.

Mining and ore processing at Corani silver-lead-zinc project

Conventional open-pit mining method will be used at the Corani project using contractor mining fleet. The mine is anticipated to extract approximately 7.87Mt of ore a year.

The processing plant is expected to have a rated capacity of 22,500 tons of ore per day (tpd). It will comprise a two-stage sequential flotation concentrator to produce a lead concentrate enriched with silver and a zinc concentrate with silver in a small volume.

The run-of-mine (ROM) ore will be initially crushed in primary gyratory crushers and stockpiled before being conveyed to the semi-autogenous grinding (SAG) and ball mill circuit.

The ore will then undergo processing in a flotation circuit comprising separate lead and zinc flotation circuits. Most of the silver will be recovered in the lead flotation circuit, while the zinc flotation circuit is expected to recover minimal silver.

At the lead flotation circuit, a concentrate will be produced from the lead sulphide, which will be further upgraded in three cleaning stages. The zinc flotation circuit comprises a rougher bank and three stages of cleaning resulting in the production of smelter-grade zinc concentrates.

The final concentrates will be thickened, filtered, and trucked to the Port of Matarani for shipment to smelters.

Infrastructure facilities at Corani silver-lead-zinc project

Access to the project is through a new 46km-long access road connecting to the Interoceanic Highway.

Surface water and groundwater for the Corani project will be collected from the watershed, which hosts the project. Contact and non-contact water will be stored in a plant water pond having a storage capacity of 782,000m³.

Power required by the project will be sourced from the Antapata substation through a new 138kV power transmission line. A new substation will also be constructed for the project, which will be connected to the San Gaban-Azangaro 138kV transmission line.

Contractors involved

M3 Engineering prepared the 2015 technical report of the Corani silver-lead-zinc project, while Sedgman Chile prepared the updated feasibility study technical report.

Graña y Montero (GMI) prepared the capital and operating cost estimates as part of the detailed engineering phase 1 (FEED), which were reviewed by GBM Minerals Engineering Consultants (GBM).

GMI partnered with Anddes Asociados SAC (Anddes) to design the main access road and with GyM to estimate the capital and operating costs. BMC prepared the economic model of the project.

Ausenco Engineering was engaged to assist the company in preparing the phase two detailed engineering study of Corani.