Alumina dispersion behavior

DETAILED DESCRIPTION We claim: 1.
An improved method for forming gel-resistant suspensions of alumina in water by mixing said alumina with dilute aqueous acid solutions, the improvement comprising treating PB alumina having a crystallite size of from 25 to 400 angstroms in a sealed autoclave prior to forming the suspension by heating said alumina to temperatures of from about 250.
degree.
F.
to about 700.
degree.
F.
in the presence of from about 10 to about 80% water based upon the weight of total alumina present and allowing the autoclave to achieve autogenous pressure for a time ranging from about 5 minutes to about 24 hours, then relieving pressure at a rate sufficient to dry said alumina and recovering said dry alumina.
2.
A method as described in claim 1 wherein the pressure ranges from about 10 psig to about 2,000 psig.
3.
A method as described in claim 2 wherein the alumina is heated at temperatures of from about 250.
degree.
F.
to about 500.
degree.
F.
in the presence of about 10 to about 30 weight percent water.
4.
A method as described in claim 3 wherein the alumina is dispersed in an aqueous acid solution containing from about 0.
4 to about 2.
0% monovalent acid by weight based upon the total dispersion weight.
5.
A method as described in claim 4 wherein the acid is selected from the group consisting of nitric, hydrochloric, acetic, formic.
6.
A stable alumina dispersion obtained from the process of claim 1.




Description:
This invention relates to a method for stabilizing alumina slurries against viscosity increases.
More particularly, this invention relates to a method for increasing the fluid life of alumina slurries by heat treating alumina under pressure in the presence of water, then forming alumina slurries using the recovered alumina and normal peptizing agents.
In this application and claims, dispersion will mean the apparent uniform distribution of alumina particles throughout a dilute acidic solution.
A stable dispersion will mean a dispersion in which the alumina particles remain homogenously dispersed throughout their observed lifetime without the use of agitation to keep the particles suspended and the dispersion remains fluid