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AssigneeProduits Chimiques Ugine Kuhlmann
InventorsRoland Bachelard, Robert Barral
Estimating the term…
Process for preparing high purity aluminas from ammonium alum, the process comprising separately dehydrating the alum and thereafter thermally decomposing the dehydrate, wherein the thermal decomposition is carried out by forcing a gas through a layer of the dehydrated alum so as to continuously remove the gaseous reaction products formed without removal of solids by the carrier gas, and providing improved productivity of high purity transition aluminas having specific surfaces above 125 m.sup.2 /g and/or bulk densities above 0.2 g/cm.sup.3, the transition aluminas so obtained being characterized by their greater reactivity for the preparation of corundum so that corundum having a bulk density greater than 0.4 g/cm.sup.3 can be economically prepared.
A process for the preparation of alumina from ammonium alum comprising first dehydrating ammonium alum at a temperature above the fusion point of the alum and below the temperature which calcines the alum to alumina and then thermally decomposing the dehydrated alum with hot gas to produce alumina, the thermal decomposition being carried out with a flow of the hot gas forced through a layer of the dehydrated alum to heat and decompose the dehydrated alum and to continuously remove the decomposition products as they are formed, the movement of the dehydrated solid alum along with the gas flow being prevented.
Dependencies are inferred from the claim text.