Tom Wilson on an obscure element and critical material with the potential to change the world – zirconium.
“Zirconium is yet another example of an obscure critical mineral with great potential in new technology where China controls the supply chain.” – Donald Bubar, President & CEO at Avalon Advanced Materials Inc.
Zirconium is a relatively obscure element that is finding increasing application in a range of new technologies. It is most commonly found in the zirconium silicate mineral, zircon (ZrSiO4), an industrial mineral used directly in many high-temperature applications. Zirconium in its many forms can now be found in cell phones, nuclear plants, dialysis machines, paint, ceramics and catalytic converters to name a few. Zirconium’s industrial use varies based on whether it is used as the metal, the oxide or a chemical compound.
With a high specific gravity, zircon is commonly found with other heavy minerals in deposits of prehistoric beach sands. It is found along with the titanium minerals ilmenite and rutile and is a byproduct from mining these sands for titanium. Heavy mineral sand resources are found in several parts of the world with much of the historical production coming from South Africa and Australia. ()As with many technology metals, the challenge of zirconium is in the economic processing of the mineral concentrates, not in mining the resource. Much of this processing is currently being done in China.
Experimental work on zircon began in the late 1700s when M.H. Klaproth performed “caustic fusion,” and extracted an interesting element which had properties not seen before. However, it was not until 1824 when J. J. Berzelius, continuing the experimentation with zircon as the starting material, actually produced a crude form of the element, zirconium. Since elemental zirconium is very reactive (particularly to oxygen), it took another 100 years before a pure zirconium metal was produced (~1923).
After World War II, the ceramic/refractory industry became interested in zircon and zirconium oxide while the Department of Defense focused on the pure metal of zirconium. Zircon’s highly-stable structure allows it to withstand the corrosive action of sodium (ie: salt) at high temperatures—a valuable property for commercial glass manufacturing. Types of glass range from plate glass (windows) to specialty pure glass for silicon chips for electronics. The ceramic industry also developed opacifiers (white, without tin) for porcelain sanitary ware. Finally, in 1948 it was discovered that zirconium oxide (Zr02), both manmade and natural, can be used to produce temperature-stable, and glaze-resistant zirconium based ceramic pigments (blue, yellow and pink). The ceramic pigment market was the main early driver for the development and production of zirconium chemicals of various types.
The stimulus which caused the need to produce a pure zirconium metal, on an industrial scale, was to supply the military with alloys of magnesium and zirconium. The second major military market development for pure zirconium metal was for cladding fuel rods to contain the uranium pellet for both the nuclear navy reactor as well as for civilian nuclear power stations.
Because of these new demands for purer forms and different compounds of zirconium, an intense effort was made to try to understand the complex chemistry of aqueous zirconium solutions. The first use (~1937) of zirconium chemical was for waterproofing of textiles such as tents for both military and commercial use.
Since this first use, the compounds and applications have expanded many times. In the zirconium industry there are two starting compounds to produce downstream products; Zirconium Oxychloride (ZOC) and Zirconium Basic Carbonate (ZBC). Generally each application requires a specific type of zirconium compound. Some of the varied applications for different zirconium compounds include: kidney dialysis, coated paper (frozen food packaging), pigment coating (Ti02), paint dries, and thixotropic paints (paints that are free-flowing and easy to manipulate while being brushed or sprayed on, but quickly set to a gel when it is allowed to remain at rest).
As industry has gained a better understanding of the chemistry; it has been able to move into the advanced ceramic/oxide applications. The advanced ceramics and oxides are both a developing and a growing market. Many of the oxides of zirconium are a mixture of zirconium and a rare earth oxide including cerium, yttrium, and lanthanum.
The production of high purity zirconium oxide is usually done through one of the above zirconium chemicals. Some applications of zirconium ceramics are: piezo-electrics (spark ignitors, sonar devices, and ultra-sonics), thermal barrier coatings (turbine blades), solid electrolytes (oxygen sensors, fuel cells), and catalysts (cracking of petroleum, catalytic convertors).
Demand for zirconium will continue to grow, because its unique physical and chemical properties will find application in many new technologies including more efficient, environmentally friendly clean technologies.