La Zanja

Gold and silver

Open pit operation

Santa Cruz, Cajamarca

3,500 masl

Started in 2010

Minera La Zanja S.R.L (53.06% BVN) is a subsidiary of Buenaventura that produces gold in an open pit mine. The mine, which was discovered by Buenaventura, is located in the District of Pulán, Province of Santa Cruz, Region of Cajamarca. It commenced operations in 2010. 

Geology: Epithermal gold mineralization in oxides associated with dome edges in San Pedro and Pampa Verde deposits. Additionally, several low and intermediate-sulfidation vein systems have been recognized on the periphery, as well as copper/molybdenum/gold mineralization related to porphyry-type systems.

Mining: Mining is performed via open pit, for which there are currently two pits in exploitation: San Pedro Sur and Pampa Verde. The height of the operating benches is 6 m and 12 m for the final slope, with an angle ranging from 36° to 54°. Ore is transported directly to the San Pedro Sur leach pad, 3 km from the San Pedro Sur pit and 10 km from the Pampa Verde pit. The barren material is transported to deposits located near each open pit. The material is loaded using 3 m3 excavators, and hauled using trucks with a capacity of 20 m3.

Metallurgy: The metallurgical process at La Zanja consists of leaching the ROM ore (obtained from blasting in the open pit) in the leaching heap using a cyanide solution. The solution is collected via pipes and sent to the processing plant. At the plant, two processes are performed: Merrill-Crowe (zinc precipitation) and activated carbon adsorption. The precipitate obtained in the Merrill-Crowe plant and the carbon loaded with ore from adsorption plant are sent to Minera Yanacocha, where the eluent solution is desorbed and smelted, and the precipitate is smelted, obtaining doré bars.

Note: As of december 31st of the year indicated.