AN INNOVATIVE INTEGRATED APPROACH TO MINIMIZING GYPSUM AND PYRITE WASTES BY CONVERSION TO MARKETABLE PRODUCTS

摘要

The objective of this research program is to develop a novel integrated process to eliminate millions of tons of gypsum and pyrite wastes generated annually by the U.S. energy industries and reduce the emission of millions of tons of greenhouse gas carbon dioxide. This was accomplished by converting gypsum and pyrite wastes to marketable products such as lime, direct reduced iron (DRI), and sulfur products and obviating the need to calcine millions of tons of limestone for use in utility scrubbers. Specific objectives included: (1) Develop a novel, integrated process for utilizing two major wastes generated by mining and energy industries to produce lime for recycling and other marketable products. (2) Study individual chemical reactions involved in pyrite decomposition, DRI production, and Muller-Kuhne process for lime regeneration to determine optimum process variables such as temperature, time, and reactant composition. (3) Investigate techniques for effective concentration of pyrite from tailing waste and methods for effective separation of DRI from calcium sulfide.