Increasing the Quantity and Quality of Metals Recovered at Waste-to-Energy Facilities

摘要

The Integrated Waste Services Association (IWSA) compiles annual data of metal recovery by U.S. waste-to-energy (WTE) facilities. The 2004 IWSA survey showed that the U.S. WTEs processed 28.8 million short tons of municipal solid wastes (MS W) and recovered a total of approximately 706,000 tons of ferrous metal scrap, i.e. 2.45% of the MSW stream. The 2001 U.S.E.P.A. report on the characterization of the U.S. wastes reported that MSW contained 7.9% metals. However, some of this metal is collected separately at the household level and a small amount is non-ferrous metal. If it is assumed that the waste stream that is "disposed" in WTE facilities contains on the average 5% of ferrous metals, the ferrous input to all U.S. WTEs is estimated at approximately 1.44 million tons. On this basis, close to 0.7 million tons of metal are not recovered in WTEs. On the same basis, the ferrous metal lost in MSW that is landfilled (247 million tons in the U.S.) is estimated to be about 12 million tons per year. The non-recovered metal at WTEs entails both environmental and economic penalties. Therefore, an industry-university collaborative study is addressed to examining a) current metal recovery before and after combustion; b) potential for increasing metal value by physical processing of the metals recovered, either at WTEs or at a regional facility to be supplied by several WTEs; c) sampling and characterization procedures used in the WTE industry; and d) potential for physical and chemical characterization of different grades of WTE metal scrap. This paper focuses on the first two subjects - the current state of WTE metal recovery and the potential for increasing metal recovery. This work in progress is published in the NAWTEC 14 Proceedings with the objective of stimulating discussion and obtaining useful input from industry and academia concerned with the conservation of non-renewable resources.