Abstract
Models of mineral production must explicitly recognize technical, economic, political, and environmental factors to allow the identification of critical components of the supply system. The world zinc industry is specified in linear programing form with a cost-minimizing objective function. Demand is fixed and inelastic, and producers are price-takers. The world is defined by 30 production and consumption regions, each with a specific schedule of cost versus capacity for mining/milling and smelting/refining, as well as consumption. Transportation and tariff costs are explicit; quotas serve as limits on intraregional transfers and to simulate trade restrictions (embargoes). Costs for mining and smelting are calculated for unit operations using a standardized estimating procedure that considers labor, materials, power, coke, overhead, depreciation, interest, taxes, and return on equity. Model simulation of the 1974-75 horizon resulted in product flows that realistically approximate the actual production of and trade in zinc concentrate and refined metal. Simulation for 1980, 1985, and 1990 projected an evolutionary development of the industry. The model is readily adaptable to minerals other than zinc and is suitable for integration with existing data bases such as the Bureau of Mines mineral availability system (mas).
