アタカマ鉱山の開発について

Abstract

In Chile, which is a mining country, based on our company’s original technology, we have opened the Atacama Mine, a copper mine, in which our company owns a 60% majority share, and are conducting operations based on our own initiative.The Atacama Mine is located about 16 kilometers SSE of Copiapo, the capital city of the Third Region in the Republic of Chile, at an elevation above sea level of approx. 500 meters. We began investigations in 1990, starting basically from scratch with almost no existing data, and found and confirmed ore deposits that could be economically mined. In 1999 we founded a joint venture company and began mine construction in 2001. At the time, the price of copper was low, so our main propositions were to reduce development costs, and shorten the development period, which we successfully completed by the end of 2002, achieving a short development period of a year and a half.Our development of the Atacama Mine had the following technological features:i) Because the ore body was deep underground (approx. 400 meters from the surface), we placed the primary ore reduction equipment underground, and used three long belt conveyors (3,500 m total) to transport the ore to the surface. This allowed us to reduce operation costs, and realize a safe and comfortable underground environment.ii) Slime is transported to a mine residue dam 16 km from the dressing plant via a fluid transport system using a pipeline, which has allowed us to reduce transport costs.iii) By using a new type of flotation machine we have been able to maximize the extraction rate of shipping ore (recovery rate of 93% or more).Four years after beginning operations the Atacama Mine continues to operate stably.