Abstract: In the fluidized bed chlorination of materials containing, for example, magnesium, manganese, calcium, iron or chromium oxides which tend to accumulate as chlorides in the bed leading to bed agglomeration, the hot partially chlorinated bed is treated with oxygen containing gas to strip out such chlorides as such or to convert them to oxides after which the chlorination may be continued. The invention may be applied, for example, to the production of titanium tetrachloride from titanium dioxide slag or the production of chromium chloride, from a chromite beneficiate.