Study On Metal Extracting Methods Of Lanzhou Petrochemical Waste Catalyst

Waste catalyst treatment has always been a difficult issue for the petroleum refining and chemical industries.It will seriously pollute the environment if it was handled improperly.At present,metal extraction in spent catalysts is an effective measure to treat spent catalysts.It not only recovers rare elements from spent catalysts,but also avoids the environmental pollution of metals in spent catalysts.Therefore,this article takes Lanzhou Petrochemical's waste tungsten-nickel catalyst as the research object,and focuses on the extraction methods of tungsten,aluminum and gallium in waste tungsten-nickel catalysts and the optimal reaction conditions.The main work of this paper is as follows:(1)First,comparing to the traditional waste catalyst metal extraction method,the organic solvent extraction method has the problems of high economic cost and high equipment requirements.In this paper,the high-temperature roasting-sodiumizing roasting-water leaching and wet-wetting method is used to extract the tungsten element from the spent catalyst.Through thermodynamic calculations,it was determined that tungsten oxide is an endothermic reaction in the baking process with sodium carbonate.At temperatures ranging from 427~oC to 727~oC,the Gibbs free energy of the calcination reaction of tungsten oxide and sodium carbonate is less than zero and this reaction can proceed spontaneously.At the same time,orthogonal experiment method was used to determine the best factor combination of this method.In the end,relying on this method,the tungsten recovery rate equivalent to the organic solvent extraction method was obtained,while the cost was effectively reduced and the tungsten element extraction was completed.(2)Secondly,taking the filter residue from the tungsten extraction process as the research object,the aluminum element is extracted by the method of sulfuric acid pickling,through the reaction mechanism and kinetics of the aluminum acid leaching process,the activation energy of the aluminum leaching process was calculated to be 56.62 KJ/mol,it shows that the acid leaching process of aluminum belongs to the chemical reaction control process in the unreacted nuclear shrinkage model.At the same time,the extraction process of aluminum extraction by acid leaching was studied by orthogonal experiments.The optimal factor combination of the process flow was determined and the orthogonal experimental results were optimized.While ensuring the high leaching rate and purity of the aluminum element,the experimental cost is saved,which provides the possibility of industrialization of the method.(3)Finally,the rare earth element tellurium in the spent catalyst was extracted by acid leaching method.The acid in the acid leaching process was selected as the hydrochloric acid by the comparative experiments.At the same time,the optimal factor combination in the acid leaching process was determined by orthogonal experiments.From the perspective of cost and ease of purification,the experimental results were optimized.The optimized factor combination was:hydrochloric acid concentration is 10%,leaching temperature is 60~oC,leaching time is 6hours,and solid-liquid ratio is 1:10.This article has effectively extracted three elements of tungsten,aluminum,and tantalum in waste tungsten-nickel catalysts.After treatment,the spent catalyst can be landfilled,which not only reduces the pollution of waste catalysts to the environment,but also can produce certain economic benefits for the extracted metals.