Silver, lead and zinc

Underground operation

Oyón, Lima

4,250 masl

Started in 2012

Mallay (100% BVN) is an underground operation discovered by Buenaventura that produces silver, lead, and zinc in the Province of Oyón, Region of Lima. It commenced operations in 2012. 

Geology: This is a fracture-filling and replacement-type mesothermal deposit, with Ag-Pb-Zn mineralization. Many of the mineralized structures are located in quartz arenites from Farrat Formation, while another part is emplaced in Jumasha limestones. The main structure is Isguiz, emplaced in the north flank of the anticlinal of the same name. From here, a series of tensional veins run E-W. In Jumasha limestone, further north, is the Pierina veins system, with similar mineralization, but with the occurrence of gold.

Mining: The exploitation of ore is primarily focused on the area known as Isguiz. The mining method used is mainly overhand cut and fill, as well as bench and fill in some parts of the deposit. The production is recirculated to the pits and the excess material is transported to the surface. The mining is performed at five operating levels, with the lowest level in development currently being 4090. Access to the veins is gained by rail, via cross-cut shafts from the surface. The main cross-cut shaft for extraction is located at level 4150, where the ore is transported by electric locomotives and mining cars to the surface and discharged into a hopper, for transport to the concentration plant via 30-ton trucks. The mine water is drained at level 4150 to settling and treatment ponds, from where it is sent to the concentrating plant and mine.

Metallurgy: Mallay Plant processes ore coming from the Mallay, Chanca, and Chacua Mines, in successive campaigns. The metallurgical process consists of the primary crushing, secondary crushing, milling/sorting, lead-silver flotation, zinc flotation, concentrate thickening and filtering, and tailings thickening, filtering, and pumping stages. The zinc-silver concentrate is sold directly.

Treatment Capacity: 600 MTD for ore from Isguiz

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