Role of Mineralogy and Geochemistry in the Beneficiation of Jajarm Bauxite from North East Iran: Comparison with some other Bauxite Deposits of theWorld

Two types of bauxite occur in the jajarm bauxite deposit, the first one is the hard bauxite and the other is the shaly bauxite orsoft bauxite. the al2o3 content ranges from 30% to 60% and sio2 varies between 5% to 39%.the total tonnage is more than 22million tons with a mean value of al2o3 content between 47% to 48% , sio2 around 10% and fe2o3 ranges between 6.95 to 27% .the jajarm bauxite deposit shows high concentration of active sio2 and fe2o3 in comparison with other bauxite deposits of theworld. efforts have been made in this research to delineate the characteristics of the jajarm monohydrate bauxites, consisting of adiaspore and chamosite mixture, to improve their chemistry by different beneficiation techniques and optimize their processing,grinding and digestion conditions for alumina production the jajarm bauxite shows politomorphic and micro- granular texture withseveral secondary textural elements. the size of diaspore grains (which is the main mineral component) are generally below 10microns, with a homogeneous matrix. in addition, for the very hard bauxite we can not do any separation between the crystal grainsand the matrix because of similar hardness for both with closely packed space filling and in consequence of the absence of welldefinedgrain boundaries. based on the above studies, the jajarm bauxite can be enriched neither by grain analysis nor by magneticseparation. in this research hard bauxite was crushed between 2 to 3 inches and then samples were washed with 5% hcl. the resultof this laboratory studies shows that the silica modulus has improved from 1.05 to 2.56 which indicates an increase of 29% in theal2o3 content. jajarm laboratory s study shows that jajarm bauxite deposit partially can be improved only by water treatment.