Recovery of molybdenum from spent hydro-refining catalysts by soda ash roasting - A statistical approach

In the present study, a hydro-refining spent catalyst with an alumina base has been taken into consideration. It is mostly used for the recovery of molybdenum. The spent catalyst constitutes around 21 pct of molybdenum as molybdenum oxide. The study has revealed that at temperature lower than 600C, it is possible to recover an appreciable quantity of molybdenum from the spent catalyst. The statistical experiments have been designed for the study to optimize the process parameters during soda ash roasting, i.e. roasting temperature, reaction time and percentage soda ash addition. In the trial run, it has been found to extract about 81% of molybdenum with temperature 500C, soda ash 20wt% when roasted for 20 minutes. The process has further been optimized and it has been possible to recover about 94% of Mo as its oxide, from the spent hydro-refining catalyst, under the optimum condition of reaction temperature 575C with 10wt. pct. soda ash addition and 45 minutes roasting time. © 2005 SDU. All rights reserved.