The kinetics of solid state CO reduction of chromite pellets and lumpy ores were studied by thermogravimetric analysis (TGA) in the temperature range 1420-1595 deg C. Optical and scannign electron microscopy as well as mcroanalysis were used to obtain information on the structural changes of the partly reduced samples. Generally, the reduction rate increased with the temeprature. In the case of lumpy ores, at the highest temperature the kinetic conditions changed due to partial melting of the surface and thus the reduction degree remained lower. In the case of sintered pellets, the effect of surface melting was not so remarkable even at the highest temperature and the reduction rate further increased. Optical photographs and microanalysis showed that the reduction degree was higher in the otuer zone of the samples. In addition the reduction fo sintered pellets with rising temperature was studied. Resutls showed that the reduction rate increased rapidly when the temperature reached about 1000 deg C and the final reduction degree was almost the same as it was in constant temperature experiment at 1520 deg C.
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