The chlorination behaviors of pure iron and manganese oxides were investigated by combining a thermogravimetric analysis (TGA) technique with batch-boat roasting followed by leaching. Ferrous and manganous oxides could be chlorinated readily, but, in the absence of a reductant, the higher oxides of both iron and manganese were difficult to chlorinate. Thermogravimetric analysis curves were drawn to illustrate the complexities of the reactions, and the possible mechanisms were discussed. Then three manganiferous materials from the Cuyuna Range of Minnesota were treated by a process involving the selective chlorination of manganese followed by leaching. The results were interpreted in the light of the chlorination mechanisms observed on the pure iron and manganese oxides.
The pure ferric oxide used in the study was of analytical grade. Magnetite and wustite were prepared from the pure ferric oxide by heating it for one hour at 900°C in a mixture of CO and CO2. For the magnetite a CO-CO2 ratio of 1:10 was used, and for the wustite 1:1 was used. Pure manganous oxide was prepared by decomposing manganous carbonate of analytical reagent grade in a nitrogen atmosphere at 500°C. Manganese dioxide of analytical reagent grade was used as purchased. Manganese tetroxide was prepared