ABSTRACT
This chapter presents ways to deal with familiar problems, in an attempt to serve as a guide to dealing with new problems as they arise. Throughout the history of civilization metals have been at the heart of technological advance. Health problems due to production and use of familiar metals generally led to regulations designed to prevent their recurrence. Ores contain only a small percentage of the desired metal, so benefaction, processing to remove a proportion of the clay, dirt, or rock that does not contain the desired metal, is necessary. Ores must be broken down into a powder. In a smelter the ore is converted to free metal by a heat and reduction process. Metals can be dissolved out of ores in a process called leaching. Metals can be hardened, throughout the object or at its surface, by a process called heat treating. Hardening is commonly done in manufacturing cutting tools, gears, bearing surfaces, and similar high-wear, high-strength products.
