As a first step in evaluating the potential of industrial wastes for use as raw materials, we will consider the flows of three metals—cadmium, chromium, and lead. Figures 3,4, and 5 report the amount of cadmium, chromium, and lead sent to major industrial waste management operations. For cadmium and chromium, only a small fraction of the material is recovered. In the case of cadmium, approximately 1,300 out-of a possible 16,000 tons were sent to recovery operations in 1986. In contrast, a major portion of lead generated as industrial wastes (106,000 out of 189,000 tons) is sent to metal recovery. Recycling is feasible for many lead-containing streams because an efficient collection and reprocessing system is in place for used automotive storage batteries. With such extensive recycling of lead, it should come as no surprise that secondary nonferrous metal processing (Standard Industrial Classification [SIC] code 3341), which is largely lead battery recycling, is the dominant source of lead wastes (Figure 6).
The flows of cadmium, chromium, and lead in industrial hazardous wastes,