Patent ID: 7597873

Claim:
A process of recovering metal oxide particles from a solution containing metal salts, said process comprising the steps of: spraying said solution containing said metal salts into an upstream end of a spray roasting reactor to form droplets of said solution, said spray roasting reactor having a single heating chamber with an upper portion at said upstream end defining a first heating zone and a lower portion defining a second heating zone; supplying a first heat source into said spray roasting reactor to said a first heating zone, and heating said droplets in said first heating zone to a first temperature to evaporate a substantial portion of liquid from said droplets to form substantially dry particles of metal salts; directing said particles of metal salts to said second heating zone and supplying a second heat source into said second heating zone of said heating chamber, said second heating zone being positioned below and downstream of said first heating zone whereby said particles of metal salts fall directly from said first heating zone through said second heating zone, and heating said particles of metal salts at a second temperature higher than said first temperature to convert said particles of metal salts to particles of metal oxides; and discharging said particles of said metal oxides from said heating chamber.