Views: 73 Author: Site Editor Publish Time: 2018-06-04 Origin: SEPPE
Bauxite is an ore which principally consists of either Boehmite (a monohydrate of alumina, Al2O3.H2O) or Gibbsite (alumina trihydrate, Al2O3.3H2O.). Raw bauxite may contain other impurities such as titania, silica and ferrous oxide. Refractory grade bauxite has a high alumina and low iron content. Most of the material mined in Europe has a higher proportion of Boehmite whereas bauxites mined in Asia and South America have high proportions of Gibbsite. The Bayer is used to process bauxite to produce higher grades of alumina (which can be used in higher temperature applications).
Bauxite used in refractory applications is generally calcined in a rotary kiln producing a material mainly consisting of corundum (alpha-Al2O3), mullite (3Al2O3.2SiO2) and a small amount of a glassy phase.So it is an artificial aggregate with higher strength and hardness than natural bauxite. Such calcination of bauxite has the properties of high alumina, low iron, high hardness, small thermal expansion coefficient, high refractoriness, and stable thermal chemical performance.