Calcined and reactive Aluminas are produced from aluminium hydroxide by calcination to products with high content of α alumina more than 90%.
According to final usage and requirements calcination is done in rotary and tunnel kilns.
Al2O3 content in the different grades ranges from 99 % up to 99.8 %. Soda content in standard grades is limited to max. 0.35 % but it can be reduced by special technologies up to max. 0.02 %
After calcination the alumina is grinded in ball mills, the finer the particles are, the higher reactivity is given.
The d50 value varies between 0.5 – 5 micron.