Various Compositions Mainly Used as Catalysts or Catalyst Components

Abstract

According to Patent (13) of the Aluminiumipari Tervezö és Kutató Intézet and Almásfüzföi Timföldgyár (Hungary) the Bayer-process for the treatment of bauxite (containing diaspores and/or goethite and/or haematite in finely dispersed state) is accelerated, goethite is transformed into haematite, which then is recrystallised. The treatment takes place at a temperature between 180° and 300°C with the application of an aluminate solution that contains 80 to 300 g/l Na₂O and a catalyst with the structural formula;

$${{\text{A}}_{\text{2}}}{{\text{B}}_{\text{3}}}/{\text{Si}}{{\text{O}}_{\text{4}}}{/_{3 - {\text{x}}}}/{\left( {{\text{OH}}} \right)_4}{/_{\text{x}}}$$

wherein A = Ca²⁺ and/or Mg²⁺ and/or Mn²⁺ and/or Fe²⁺ and B = Al³⁺ and/or Fe³⁺ and/or Cr³⁺. The catalyst is added in a quantity amounting to 5–20% of the dry bauxite. The process increases the alumium yield.