Zirconium and hafnium

Zirconium is produced from two ore minerals. The principal economic source of zirconium is the zirconium silicate mineral zircon (ZrSiO 4 ). The mineral baddeleyite, a natural form of zirconium oxide or zirconia (ZrO 2 ), is a distant second to zircon in its economic significance. Zircon is the primary source of all hafnium. Zirconium and hafnium are contained in zircon at a ratio of about 50 to 1. Zircon is a coproduct or byproduct of the mining and processing of heavy-mineral sands for the titanium minerals ilmenite and rutile or tin minerals. The major end uses of the mineral zircon are refractories, foundry sands (including investment casting), and ceramic opacification. Zircon is also marketed as a natural gemstone, and its oxide is processed to produce cubic zirconia, a diamond and colored gemstone simulant. Zirconium metal is used in nuclear fuel cladding, chemical piping in corrosive environments, heat exchangers, and various specialty alloys. The principal uses of hafnium are in nuclear control rods, nickel-based superalloys, nozzles for plasma arc metal cutting, and high-temperature ceramics. World production of zirconium mineral concentrates was estimated to have increased slightly in 2000. Data on U.S. production and consumption of zircon concentrates were withheld to avoid disclosing company proprietary data. Domestic production of zircon increased as a heavy-mineral sand mining operation in Virginia continued to improve recovery rates and scale-up production. In 2000, production of milled zircon was essentially unchanged from that of previous years. According to U.S. Census Bureau trade statistics, the United States was a net exporter of zirconium ore and concentrates. U.S. imports of zirconium ore and concentrates increased by 13%, and domestic exports of zirconium ore and concentrates increased by 5% compared with 1999. With the exception of prices and referenced data, all survey data in this report have been rounded to no more than three significant digits. Totals and percentages were calculated from unrounded numbers.