What is the difference between tabular alumina and fused alumina?
Fused Alumina fused alumina manufacturers
Fused alumina is made in electric arc furnaces by passing a current between vertical carbon electrodes. The heat generated melts the alumina. The furnace consists of a water cooled steel shell and 3-20 tonne batches of material are fused at any one time. The fused alumina has a high density, low porosity, low permeability and high refractoriness. As a result these characteristics, it is used in the manufacture of abrasives and refractories.
Calcined AluminaIf aluminium hydroxide is heated to a temperature in excess of 1100ºC, then it passes through the transition phases of alumina referred to above.
The final product, if a high enough temperature is used, is α-alumina. The manufacturing process is commercially undertaken in long rotary kilns. Mineralisers are frequently added to catalyse the reaction and bring down the temperature at which the α-alumina phase forms; fluoride salts are the most commonly used mineralisers.
These calcined alumina products are used in a wide range of ceramic and refractory applications. The main impurity present is sodium oxide. Various grades are produced which differ in crystallite size, morphology and chemical impurities.
The calcined grades are often sub-divided into ordinary soda, medium soda (soda level 0.15-0.25% wt%) and low soda alumina hslabrasive