Recovery of Alumina from Anorthosite by an HCI-F-Gas Sparging Crystallization Process

摘要

The Bureau of Mines is investigating the recovery of alumina from domestic nonbauxitic resources, including anorthosite. The United States has large reserves of anorthosite, but its aluminum content is less than 50 pct soluble in acid, unless a source of fluoride is added to the acid. A flowsheet that includes leaching with HC1 and fluoride followed by crystallization of of A1C13:6H20 from the pregnant liquor by HC1 gas injection was designed. Approximately 90 pct of the aluminum values were recovered from the anorthosite when a ratio of 0.14 mole of fluorine per mole of aluminum was used. Sodium chloride is cocrystallized with the A1C13 : 6H20 but is removed by water washing of the A1203 product. A material balance is given based on results of laboratory studies of the unit operations.