Valuable metals recovery from spent catalysts by selective chlorination

The food, chemical, petroleum, petrochemical and other industries generate thousands of tons per year of spent catalysts containing up to 35% valuable metals such as Co, Cr, Cu, Ni, Mo, Ti, V, W. The recycling of these materials will lead to provision of significant quantities which are currently imported from outside the EC countries and could contribute to the improvement of the environment. Selective chlorination of these spent catalysts with different chlorinating gas mixtures between 300 and 600°C is investigated for the recovery of their valuable elements. Depending on the experimental conditions, it is possible to recover up to 98% of the Ni and Co, as chlorides from the chlorination residue and about 98% of the Mo, Ti & W and 80% of vanadium compounds in the condensates. The catalyst support chlorination could be limited to less than 5%. Besides the reaction temperature and time, the oxygen partial pressure in the chlorinating gas mixture is a key factor for the selectivity of the chlorination.