On occasions, lime ( CaO ) is also introduced into the Bayer process because it enhances the extraction of alumina, controls liquor impurities, assists with the removal of impurities from the sodium aluminate solution, and minimizes soda losses in the red mud.
12.
Some of the aluminium hydroxide produced is used in the manufacture of water treatment chemicals such as aluminium sulfate, PAC ( Poly aluminium chloride ) or sodium aluminate; a significant amount is also used as a filler in rubber and plastics as a fire retardant.
13.
A few years earlier, Henri �tienne Sainte-Claire Deville in France developed a method for making alumina by heating bauxite in sodium carbonate, Na 2 CO 3, at 1200 �C, leaching the sodium aluminate formed with water, then precipitating aluminium hydroxide by carbon dioxide, CO 2, which was then filtered and dried.
14.
The company began with two salt wells in 1850, and continued operations until 1959 . By 1876, the company, which owned the cryolite deposits of Greenland, brought the crude mineral to its works in Natrona, where the mineral was pulverized, sifted, heated, reacted with calcium carbonate and leached to produce pure carbonate of soda ( sodium carbonate ) and aluminate of soda ( sodium aluminate ).
