Font Size: a A A

Study On The Recovery Of Rare Earth Lanthanum And Cerium From Spent FCC Catalyst

Posted on:2015-06-15Degree:MasterType:Thesis
Country:ChinaCandidate:W X LiFull Text:PDF
GTID:2181330422983776Subject:Physical chemistry
Abstract/Summary:PDF Full Text Request
FCC catalyst is a good activity product modified by rare earth elements andmanufactured by Lanzhou Petrochemical. As the various reasons, the catalytic activitygradually lower, and it have to add some fresh catalyst and unload spentedcatalyst tomaintain the activities. Most of the spent catalyst will landfill after pre-processing, butit is also an important resource containing both Lanthanum Cerium and other rareearth elements, which resulting waste a large number of rare earth resources, therefore,how to recycle the rare earth elements efficiently from spent FCC catalyst is an urgentproblem in the research of chemical analysis need to be solved.So far, much attention has been focused on the concentrated acid leach processfor recycling in our country, but the separation process of concentrated acid leachingis extremely complex, higher recycling costs, and haveagreater impact on theecological environment. According to the state and trend, in our work, the optimalconditions are found out and a relatively large amount of rare earth elements arerecycled in the spent FCC catalyst at a lower cast in the process of removingframework aluminum release of rare earth elements. The main contents are as follows:1. Spectrophotometric method, EDTA titration method and extraction-ultravioletspectrophotometry were employed to measure the rare earth content in the spent FCCcatalyst. The analysis results show that extraction-ultraviolet spectrophotometrymethod with high accuracy, good selectivity, low cost and precision meet the analysisrequirements, it can be used for determination of lanthanum and cerium in FCCcatalyst and acid leaching.2. Effects of calcining temperature, acid type, acid concentration, liquid-solid ratio,leaching temperature and leaching time on leaching efficiency of rare earths in spentFCC catalyst were evaluated. The results show that roast to remove carbon and acidleaching solution concentration increased can significantly improve the leachingefficiency of lanthanum and cerium; liquid-Solid ratio is larger, the higher theefficiency of acid leaching; Hydrochloric acid and nitric acid leaching solution can be extracted and recovered cerium and lanthanum elements from the FCC catalyst, butthe aluminum content in nitrate leaching solution is lower, which can facilitatesubsequent separation and determination. Leaching efficiency of rare earths were94.5%and92%respectively under the condition of3mol/L HCl or HNO3, calciningtemperature600oC, liquid to solid20:1, leaching temperature85oC and leaching time4h.3. The leaching liquor was puried through oxidation and neutralization treatment, thenadding oxalic acid to to precipitate the rare earth, the rare earth oxide was beenachieved by roasting. The influence of different precipitation methods on rare earthsedimentation rate and purity of rare earth oxides were studied. The results show thatthe rare earth oxide (REO) products with REO content of95%can be obtained.4. P204as extractant, Extraction Behavior of rare earth elements in the leachingsolution was studied, the effect of pH, extracting agent consumption, extraction time,phase ratio and hhydrochloric acid concentration on extraction efficiency wereinvestigated. The best conditions are as follow: extractant concentration (volumeconcentration of P204) is60%, the phase ratio is1:1, pH is3, the equilibrium time ofextraction is5min, the back-extract concentration of hydrochloric acid is2.0mol/Land the phase ratio of back extraction is1:1. Under this condition, the total content ofrare earth P204extract can reach97%and separation of rare earth and non-REimpurity was achieved.
Keywords/Search Tags:Spent FCC catalyst, Rare earth element, Acid leaching, Oxalic acidprecipitation, Extraction
PDF Full Text Request
Related items