Open pit operation
Minera Yanacocha S.R.L. (43.65% BVN), an affiliate of Buenaventura, operates an open pit gold mine located 45 km north of the city of Cajamarca. Its activities commenced in 1993. Yanacocha is operated by Newmont.
Geology: This is a cluster of high-sulfidation epithermal gold deposits from the Middle Miocene Epoch. Gold mineralization in oxides is related to a series of volcanic centers that run for 14 km to the northeast, and includes the Cerro Negro, El Tapado, Yanacocha, San José, Carachugo, Chaquicocha, Quecher, and Maqui Maqui deposits. The oxidation profile reaches 200 m, on average. Below this level, there are occurrences of arsenical copper with indications of copper porphyries at depth, as with the case of Kupfertal.
Mining: Mining begins with drilling in the terrain, creating boreholes that are then filled with explosive materials. When detonated, these explosives fragment the rock and stir up the material at the subterranean level, exposing it at the surface. During this stage, the highest safety standards are applied. The blasts implemented and the subsequent stirring of the earth begin to form large holes in the land known as pits. Giant trucks (which can carry up to 250 tons of earth) carry the ore extracted from the pit to the leaching heap (or “pad”), which is the structure where the ore extracted from the mountain is piled up to be leached, and thus recover the gold existing inside it.
Metallurgy: The gold-bearing ores of Yanacocha are transported to the leaching heaps for gold recovering using the conventional extraction method via leaching, followed by zinc powder precipitations in the Merrill-Crowe system, and subsequent smelting, where the final product is a doré. The doré is sent outside the facilities for refining and is sold on gold markets around the world. Yanacocha also has a Gold Mill Plant, which consists of a pulp leaching process after milling the ore. The Gold Mill processes 20,000 MTD, and includes the SARC process, which precipitates the copper and silver and recovers the cyanide.
Note: As of december 31st of the year indicated.