Bayer, Karl Josef

The Bayer Process, patented by Karl Josef Bayer in 1888 (Pearson (1)) is still widely adopted in refining alumina trihydrate from bauxite. Despite its long history, the unit operations involved in the process have remained basically unchanged with the reversible reaction below as its backbone. 

The production of aluminum actually involves several steps. Bauxite is the ore that contains aluminum oxide (Al Oj) used to produce aluminum. Impurities of iron, sulfur, silicon and other elements are removed from bauxite using the Bayer process to produce purified alumina. The Bayer process, patented in 1887 by Austrian Karl Josef Bayer (1847-1904), involves pulverizing bauxite and treating it with a hot sodium hydroxide solution to produce sodium alu-minate (NaA102). Sodium aluminate is then placed in a reactor in which temperature and pressure can be varied to precipitate out impurities. The sodium aluminate solution is then hydrolyzed to produce purified alumina ... 

Iron(III) oxide or alumina is refined from bauxite. Approximately 175 million tons of bauxite are mined annually worldwide, with virtually all of this processed into alumina. Alumina is a white crystalline substance that resembles salt. Approximately 90% of all alumina is used for making aluminum, with the remainder used for abrasives and ceramics. Alumina is produced from bauxite using the Bayer process patented in 1887 by Austrian Karl Josef Bayer (1847-1904). The Bayer process begins by grinding the bauxite and mixing it with sodium hydroxide in a digester. The sodium hydroxide dissolves aluminum oxide components to produce aluminum hydroxide compounds. For gibbsite, the reaction is Al(OH)3 + NaOH —> Al(OH)4 + Na+. Insoluble impurities such as silicates, titanium oxides, and iron oxides are removed from the solution while sodium hydroxide is recovered and recycled. Reaction conditions are then... 

Although developed as early as 1888 by the Austrian chemist. Karl Josef Bayer, the Bayer process still is used abnost exclusively for the extraction of alumina from ores, The bauxite first is reacted under pressure with hot caustic, which dissolves the ALO3 xH20 to form sodium aluminate, The solution is filtered hot. then cooled and agitated with the addition of a small quantity of aluminum hydrate to enhance the precipitation of the crystalline hydrate. After filtration, the cake is kiln-dried at 1100 °C to remove H20 and yield A1203... 

F. Habashi, Karl Josef Bayer (1847-1904), in F. Habashi (Ed.), Progress in Extractive Metallurgy, Vol. 1, pp. 1-16, Gordon and Breach, New York, 1973. 

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