Treatment of Metal Finishing Wastes

Abstract

In the metal finishing industry, metals or alloys are used as starting materials to manufacture a wide range of metal components. The metal finishing and metal fabricating industry is identified as SIC (Standard Industrial Classification) code 34. SIC code 34 is further divided into nine classes: SIC 341 to SCI 349. These subclasses indicate product groups [1]. Metal finishing involves the forming and shaping of metals and the altering of surface properties to enhance corrosion resistance, electrical conductivity or resistance, wear resistance, chemical and tarnish resistance, solderability, torque tolerance, ability to bond rubber and adhesives or organic coatings, hardness, reflectivity, and decorative appearance. A broad range of processes is employed in the metal finishing industry. Metal fabrication covers mostly mechanical operations such as cutting and forming. Surface treatment involves plating, conversion coating, anodizing, painting, heat treating, and many other operations. Degreasing, cleaning, pickling, and etching are supporting processes. The industry manufactures a wide range of metal components such as cans, hand tools, hardware, cutlery, and structural metal products. Many industries use metal finishing in their manufacturing processes. Metal finishing is an essential part of a number of industries including automotive, electronics, defense, aerospace, hardware, heavy equipment, appliances, telecommunication and jewelry. With this profile, the metal finishing industry is among the most common industrial activities in the United States and in many other countries as well. While production methods and applications are similar in all metal finishing plants, capacities vary widely. Metal finishing facilities are grouped into two major categories: captives and job shops. Captive facilities are part of a larger operation and perform metal finishing processes on in-house manufactured parts. The plants in this category tend to be larger in capacity than job shops. Job shops are independently owned small plants that rely on a variety of customers and work on the parts manufactured by others. Job shops may also be used as subcontractors by the captive facilities. This application tends to be more common [2]. Captive facilities are more specialized in their operations, while job shops are more flexible in operations to respond to the varying demands of customers.