156 157 cerro de pasco The greatest investment of the XXth century we let them roam around the camp. They found and ate the snakes”. It was with the pigs that they implemented an effective biological control system to eradicate the snakes. In those three months there were no weekends or breaks, as they were away from everything and there was practically nothing to do. They even got used to the tarantulas. They were impressive but also quite slow. Del Castillo himself remembers it with a smile: “You only had to be careful that they did not raise their front legs, because that gesture preceded an attack leap that could exceed a metre in distance. Bob Dixon, whom I replaced in supervision, caught one, dissected it in a threatening position, and hung it on one of the office walls. Since then, every time a new official arrived, he was brought in and when he placed him next to the wall, everyone shouted ’Look out, tarantula!’ and ended up laughing at the leap of the newcomer in the Cobriza style”. Although the company had been targeting the deposit since the 1920s, the distance between its location and the mining corridor ended up delaying its impending exploitation. The silver and copper deposits were extremely attractive, however the difficulties of access in an area of deep valleys made it economically untenable. Nonetheless, patience paid off, conditions changed by the mid-1960s and, precisely, in 1966, the corporation began construction of the metallurgical facilities and necessary services, such as a new camp and a 64 kilometre road. In December 1967 the mine entered production at an average rate of 1,000 metric tonnes per day and was officially inaugurated on July 14, 1968. The result was a copper concentrate with some silver and bismuth, which allowed the annual copper production of Cerro-Peru to increase by more than 9 thousand tonnes. Beyond the high-grade reserves, the deposit contained an even greater amount of low-grade copper mineralisation, prompting early expansion of the project from the outset. A few years later, the Cobriza production was the company’s main source of copper and represented the most modern model of production in an underground mine. Its concentrator plant began treating 1,350 tonnes per day, but managed to produce 660,000 tonnes per year. At that time, the Cerro de Pasco mine had higher production, but mainly of lead, zinc and silver, of which 55% was from the McCune Pit. Yauricocha, San Cristobal and Casapalca continued to produce copper in smaller quantities and, always, accompanied by lead, silver and zinc. The new wagers As well as the extensions and improvements of the facilities, two new projects were also started at this time. In Cerro de Pasco, a precipitation plant was put into operation to recover copper from mine wastewater and from leaks near waste and slag deposits. By then, unorthodox systems and temporary installations were used to recover the residual copper that escaped with the water. According to the same engineer Guido del Castillo, the acidic water from the Excelsior mine was led through a channel to which, at one end, old cans of condensed milk were deposited to attract the copper residues. These remains stuck to the surface of the cans that were later transported as copper scrap to La Oroya for metallurgical recovery. Only by this method it was said then, that the value of recovered copper reached one million dollars a month. With the implementation of this plant, the recovery rates from that source doubled. On the other hand, in La Oroya two plants were built in the name of Compañía Industrial del Centro S.A. o CICSA, a subsidiary company of the corporation, which was established taking advantage of the legislation that encouraged investment in high-altitude territories. One was of sulphuric acid, capable of producing 200 tonnes per day, whose final product would be used by THE GROWTH OF THE COMPANY IN THE 1950s ALLOWED INCREASING THE CAPACITY OF THE CONCENTRATOR PLANTS AND RENEWING THE RAILWAY INFRASTRUCTURE.
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