Process for producing metal hydroxides with a small specific area
AssigneeChemson Polymer-Additive Gesellschaft m.b.H.
InventorsDieter Wurmbauer, Heinz Krivanec
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Abstract
The invention concerns a process for producing metal hydroxides with a small specific area in which the metal hydroxide is produced by hydrating a corresponding metal oxide and then treating it under pressure in an autoclave.
Claims17
Process for preparing metal hydroxides of small specific surface, wherein a metal hydroxide is first formed by hydrating the corresponding metal oxide in the presence of water but under exclusion of an autoclave treatment, and the metal hydroxide is subsequently treated under pressure in an autoclave at temperatures between 100.degree. C. and 200.degree. C. until a specific surface of less than 20 m.sup.2 /g is obtained.
Process for preparing magnesium hydroxide of small specific surface, wherein magnesium hydroxide is first formed by hydrating magnesium oxide in the presence of water but under exclusion of an autoclave treatment, and the magnesium hydroxide is subsequently treated under pressure in an autoclave until a specific surface of less than 10 m.sup.2 /g is obtained,
- wherein the magnesium hydroxide is charged into the autoclave in the form of an aqueous suspension,
- wherein a suspension with a solids content between 30 and 50 wt % is charged into the autoclave,
- wherein the hydration of the magnesium oxide into the magnesium hydroxide is carried out by using deionized water,
- wherein the step of hydration of the magnesium oxide into the magnesium hydroxide is carried out at a temperature of less than 60.degree. C.,
- wherein the magnesium hydroxide first formed by hydrating the magnesium oxide is washed and/or ground prior to the autoclave treatment,
- wherein the magnesium hydroxide formed first formed by hydrating the magnesium oxide is ground to a fineness d.sub.50 between 1 and 4 microns,
- wherein the autoclave treatment is carried out by using live steam,
- wherein the autoclave treatment is carried out at temperatures between 140.degree. C. and 180.degree. C.,
- wherein the autoclave treatment is carried out over a period of 2 to 24 hours,
- wherein the suspension is circulated in the autoclave, and
- wherein the material removed from the autoclave is subsequently spray-dried.
Dependencies are inferred from the claim text.