Spray calcination and drying process to produce high-purity alumina

A process for preparing high-purity aluminum oxide, the process comprising:

• providing an aluminum feedstock;
• reacting the aluminum feedstock with one or more acids to form a first hydrated aluminum salt solution;
• precipitating at least a portion of the hydrated aluminum salt from the first hydrated aluminum salt solution to produce a mixture of precipitated hydrated aluminum salt crystals and a mother liquor;
• separating the precipitated hydrated aluminum salt crystals from the mother liquor;
• dissolving the hydrated aluminum salt crystals in a solvent to form a second hydrated aluminum salt solution;
• and
• calcining hydrated aluminum salt of the second hydrated aluminum salt solution to form an aluminum oxide powder.

A furnace comprising:

• a cylindrical or substantially cylindrical side wall;
• a frustoconical bottom wall coupled to and angled inwardly from a vertical bottom end of the cylindrical side wall to vertically cover the bottom of the furnace interior;
• a domed or rounded top wall coupled to a vertical top end of the cylindrical side wall and vertically covering the top of the furnace interior;
• one or more combustion burners configured to direct a flame toward the furnace interior with a velocity of flame creating an air flow within the furnace interior;
• a inlet for supplying a material to be dried or calcined by the furnace;
• and
• an outlet for exit of a dried or calcined material from the furnace.