ABSTRACT
I. INTRODUCTION Almost 530,000 tons of scrap copper metal per year are recycled in the United States. This accounts for about 24% of total U.S, consumption (U.S. Bureau of Mines, 1991). Recovered copper in electronic scrap is small in comparison, representing about 15,000 tons of copper from 75,000 tons of waste per year (Sum, 1991). Electronic scrap accounts for iron (30,000 tons), tin (15,000 tons), nickel, lead, and aluminum (7500 tons each), and zinc (3800 tons). The precious-metal value, which is the primary economic reason for the reclamation of electronic waste_, accounts for 380 tons of gold, twice that in silver, and some palladium. Both of these sources of reclaimable metals are significant. It has been estimated that there are 244 ·million tons of metal-bearing hazardous wastes that are produced annually from the metal-related industries (see Brooks, 1991). Although the metal content of these wastes was not specified, it is expected that reclamation of metals from such sources could account for significant additional resource recovery. These wastes consist primarily of inorganic sludges and solids containing several metals, predominantly present as hydroxides and basic metal salts. A recent selective analytical survey of one specific waste type, electroplating sludges (Odle et al., 1991), found an average metal content of 16.4% copper, 7.5% nickel, and 3.6% zinc. For copper, nickel, and zinc electroplating sludges, the metals averaged 8.4%, 8.9%, and 8.9%, respectively, with an
average iron content of 4.4% and calcium content of 5.4%. This is not intended to suggest that the metal-containing hazardous waste sludges contain 8-16% copper, but it is intended to indicate the magnitude of the metal waste problem. Metal wastes are primarily generated by the electronic, electroplating, metal finishing, and machining industries, and as consumer waste. Significant quantities of metal-containing spent catalysts are also produced by the organic chemical industry. Much of the metal-bearing waste is classified as hazardous by the U.S. Environmental Protection Agency (EPA). This classification may be due to characteristics such as corrosivity or toxicity; however, the classification may be arbitrarily assigned by the EPA due to the specific nature of the waste source (see Chapter 14). The reclamation of metals from these types of wastes presents several regulatory concerns. Odie (1991) has recently addressed many of the concerns and disadvantages to recycling and reclamation of metals from hazardous waste. The current attitudes of government regulators and waste generators more often than not impede the recycling of these types of waste. Segregation of waste by type is not encouraged, and in many cases, no incentives are given the generator to choose recycling over landfilling. The residues produced during the processing of listed wastes are designated hazardous, not by virtue of characteristics but because they are "derived from" listed wastes. Many of these types of regulations do little to encourage the recycling efforts, and in fact, impede the efforts to clean up the ·environment.
