Method for preparing spheroidal alumina

In a method for preparing high density, high crush strength spheroidal alumina from alumina hydrates by the oil drop method wherein an alumina sol or dispersion is prepared by reacting alumina hydrates with a dilute aqueous acid and the alumina sol or dispersion introduced as droplets into the upper end of a forming column filled in its upper portion with a liquid hydrocarbon and in its lower portion with an aqueous solution of ammonia, the improvement comprising

• (a) preparing an alumina sol or dispersion having a solids content greater than 20 and up to 40 percent by weight alumina from alumina hydrates consisting of 10 to 40 weight percent boehmite and 90 to 60 weight percent pseudo-boehmite prepared by hydrolysis of aluminum alkoxides and characterized by a boehmite primary crystallite size of 60 to 65 Angstroms and a pseudo-boehmite primary crystallite size of 35 to 40 Angstroms as measured by X-ray diffraction 020 reflex,
• (b) incorporating 1 to 10 percent by weight urea in the alumina sol or dispersion prepared in step (a),
• (c) dispersing the resultant urea-alumina sol composition in droplet form into the forming column which is kept at room temperature, and
• (d) drying and activating the thus formed spheroidal particles.