Thermal Technology (Santa Rosa, Calif.) has delivered and installed a high-temperature zone refiner. The system is capable of refining alumina at a temperature of 2200°C (3992°F). In order to reach these temperatures and not contaminate the alumina, a 100% tungsten heating system and a transport system fabricated primarily of tungsten were utilized. The high-temperature zone refiner was custom built to meet the customer’s strict requirements. According to Thermal Technology, the system operates at extended temperatures for a period of days or weeks refining oxides to purity levels not commercially available.
Zone refining, as a process, has been used to purify metals for decades. It is typically applied to materials with melting points in the range of 600-1200°C (1112-2192°F). When the need to zone refine oxides with melting points over 2200°C arises, custom-designed systems are necessary.