write a note on bayers process imvolved on leaching of alumina from bauxite ore
Answers
• on refining bauxite by Bayer's method to obtain pure aluminium oxide is obtained.
• in this method, 45% concentrated caustic soda solution is added to bauxite and then heated INA closed vessel at about 433k temperature and 5 to 6 bar pressure, for 6 to 8 hours, so that bauxite is converted into soluble sodium aluminate.
the soluble impurities collected at the bottom are separated by filtration.
•. soluble sodium aluminate is mainly there in the filtrate. excess of water is added to it and on constant stirring,it's hydrolysis takes place and whites gelatenious precipitation of aluminium hydroxide are obtained.
about 99.5% pure alumina is obtained by Bayer's method.
In bauxite,in addition to aluminium oxide impurities like iron oxide and sand are present.
On refining bauxite by Bayer's method to obtain pure aluminium oxide is obtained.
In this method, 45% concentrated caustic soda solution is added to bauxite and then heated INA closed vessel at about 433k temperature and 5 to 6 bar pressure, for 6 to 8 hours, so that bauxite is converted into soluble sodium aluminate.
the soluble impurities collected at the bottom are separated by filtration.
Soluble sodium aluminate is mainly there in the filtrate. excess of water is added to it and on constant stirring,it's hydrolysis takes place and whites gelatenious precipitation of aluminium hydroxide are obtained.
about 99.5% pure alumina is obtained by Bayer's method.