Results of investigations over approximately 10 yr by the Bureau of Mines and others on technology for recovering cell-grade alumina from domestic nonbauxitic resources such as clay, anorthosite, alunite, dawsonitic oil shale, coal ash, and coal shale are reviewed. It is concluded that, although many innovative techniques have evolved from this effort and have been shown to be technically feasible, energy and economic considerations will prevent any of the processes from competing with the Bayer process under normal conditions. Based on the Bureau's experience, some variation of clay-hcl leaching, hcl gas sparging crystallization has the greatest potential as an alternative to the Bayer-bauxite process.
Proc. 1984 Bauxite Symposium Soc. Min. Eng. AIME, New York, Mar. 1984, PP. 165-199