Use of chlorination for chromite upgrading

The chlorination of a chromite concentrate was studied between 600 and 1000 degrees C. The reaction products were analyzed by scanning electron micros copy (SEM), X-ray diffraction (XRD), and chemical analyses. Chlorination of a chromite concentrate at about 700 degrees C allowed the extraction of ab out 50% of the iron, thus doubling the Cr/Fe ratio in the treated concentra te. Aluminum chloride was tested as a chlorinating agent in the presence of a reducing atmosphere. The effect of temperature on the kinetics of chromite chlorination was stud ied between 900 and 1040 degrees C using thermogravimetric analysis (TGA). Temperature effects changed significantly with reaction extent. The initial stage of the chlorination was characterized by an apparent activation ener gy of about 112 kJ/mol, while a value of about of 269 kJ/mol was found for reaction extents greater than 0.4. (C) 2000 Elsevier Science B.V. All right s reserved.