Zone Refining : Method of purifying solid rods by means of melting narrow zones through the rods. These zones are slowly moved from one end of the rod to the other, sweeping out the impurities
US Department of Labor, Electric Power eTool: Glossary of Terms, Occupational Safety & Health Administration OSHA, Washington, D.C., USA 2010. https://www.osha.gov/SLTC/etools/electric_power/gl ossary.html, (OSHA/ Electr Pwr - Amer) {618}