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CODELCO, Chile programs its copper-smelting operations.

Article Excerpt
CODELCO's Chuquicamata Copper Smelter, located in Chile, must meet an environmental standard established in 2002 that limits the sulfur emissions from the copper-production process. This regulation placed new restrictions on the production process, and consequently the heuristic criteria based on years of operator experience no longer resulted in high production levels. We developed a model to maximize production while respecting metallurgic, operational, environmental, and other restrictions. We created two methods of planning daily activities for the plant. We developed a client-server tool that displays optimization results graphically and numerically based on data on operational conditions recorded in real time and data input manually. The smelter has used the system since March 2003. We found an increase in the quantity of copper concentrate processed of 25.4 percent.

Key words: production, scheduling: approximations, heuristics; industries: mining, metals.

History: This paper was refereed.

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CODELCO (Corporacion Nacional del Cobre) in Chile produces copper, the principal export of this country, with sales in 2004 of $8,204 million. Copper concentrate smelting is one of the principal stages in the production of copper. Until March 2003, CODELCO's Chuquicamata concentrate smelter planned its operations according to heuristic criteria based on the general shift manager's experience. For many years, this method allowed the smelter to reach its strategic and tactical production goals. New environmental legislation requires the company to reexamine these procedures. It cannot use historical criteria to meet its productivity goals. It must consider many combinations and elements to achieve maximum productivity, use a model to represent the problem, and develop a method of obtaining a good solution.

The problem is characterized by many possible combinatorial solutions, nonlinear factors intrinsic to the metallurgical processes, and accumulated experience on the part of decision makers.

The Problem

The Chuquicamata mine's smelting process involves two stages: a smelting stage and a conversion stage. The smelting stage converts copper concentrate, with 29 to 33 percent purity, into a high temperature liquid mixture with a higher copper purity depending on the equipment used: a flash furnace (FF) or one of the teniente converters (TC-1 and TC-2). The FF converts copper concentrate into a liquid mixture, called matte, that is 62 to 68 percent copper; while the TCs convert the copper concentrate into white metal, which is 70 to 75 percent copper (Figure 1).

[FIGURE 1 OMITTED]

The resulting copper mixture, either matte or white metal, contains copper, iron, and sulfur, and requires further purification, which takes place in Pierce Smith converters (PSC-1, PSC-5, PSC-6, and PSC-7) during the conversion stage. Huge ladles transport, the high-temperature, liquid mixture from the FF or TCs to the...

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