Research on the vanadium extraction from deactivated sulfuric acid catalyst featured with two-step and selectively
Based on the limited selectivity exhibited by current direct acid leaching and alkaline leach-ing processes for deactivated sulfuric acid catalysts,resulting in costly subsequent separation and chal-lenging medium reuse,a new two-step process for selective extraction of vanadium was adopted.Using the strong water solubility of potassium and sulfur,the influence of washing temperature and pH value on leaching of potassium and sulfur was studied.It was found that potassium and sulfur can be removed more than 80％and 96％respectively by water washing under the condition of temperature 40～60℃and pH 3～5,while the loss rate of vanadium was controlled within 10％.Thus,the selective separation of vanadium from potassium and sulfur was realized.In the second step,based on the leaching character-istics of vanadium and silicon in an alkali medium,the effects of leaching temperature,time,liquid-sol-id ratio and alkali concentration on vanadium extraction were studied.It was found that after reaction with 5％NaOH solution at 80 ℃ and L/S=5 for 30 min,more than 95％vanadium was deactivated from the sulfuric acid catalyst,while the silicon leaching rate kept almost zero.The vanadium-contain-ing leaching solution can be handled by calcification and ammonium process to obtain ammonium metavanadate products.The NaOH solution can be recycled to vanadium extraction step and wastewa-ter zero emission was achieved.
deactivated sulfuric acid catalystextraction of vanadiumalkaline leachingammonium metavanadate
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