A PROCESS FOR PRODUCING DENSE HIGH ALUMINA CONTENT GRAINS FROM LOW-GRADE BAUXITE ORES AND FINE GRAIN BAYER'S ALUMINA

摘要

The invention provides a process for producing dense high alumina content grains from low grade Bauxite ores and fine grain Bayer's alumina, comprising the following steps in sequence :- l) crushing the low grade Bauxite ores in primary and secondary crushers into particles of size (-60)B.S. mesh; ii) passing the crushed Bauxite ores through a magnetic separator to remove magnetic particles; iii) pulverising the particles and leaching the pulverised particles with (N/5) HC1 acid for 2 hours at 80°C to remove CaO as CaCl2 solution; iv) passing the particles again through a wet high intensity magnetic separator (WHIMS) to remove magnetic materials; bauxite v) mixing the/particles with calcined fine grain Bayer's alumina in 40:60 ratio by weight; vi) wet milling the mix in a ball mill; vii) passing the mix through a blunger and filter press and drying the same in a dryer; viii) dividing the mix into two parts, one part being sintered in a kiln at 1500°C, crushed in a crusher/grinder, passed through a magnetic separator and transferred to storage, and the other part being crushed in a crusher/grinder, mixed thoroughly in a mixer, pressed into cylinder forms of diameter 50 mm in a hydraulic press at a pressure of 500 Kg/cm , sintered in kiln, at 1500°C, crushed in a crusher/grinder, passed through a magnetic separator and transferred to storages. The dense high alumina content grains produced are of physical characteristics '• colour - dark grey, density - 3.33 gm/cc, porosity - 2.86% and water absorption - 0.85%; and of chemical composition (by weight %) : A1203 - 88.33, Ti02 - 1.11, Fe2O3, - 2.56, Si02 - 5.55, CaO - 1.17, MgO - 0.44, Na20 - 0.44, K2O - 0.11 and Others - 0.29.