(00498)A Simple and Flexible Flowsheet Process for Efficient and Selective Metal Recycling from Spent Fluid Cracking Catalysts

摘要

This paper investigates the recovery of the main metals (La and Al)present in a spent fluid cracking catalyst (FCC)through the hydrometallurgical processes of leaching and selective precipitation. Complete La leaching (99±1)% was achieved under microwave-assisted leaching with the use of 1 M HCl and a liquid-solid (L/S)ratio of 5 for 90 s. Since the main impurity presented in the leachate was Al, an initial process was developed to selectively recover Al by alkaline precipitation. At pH 6, almost total Al (98%)was precipitated with purity of 88.7% while La co-precipitation was insignificant (2.8%). The second approach consisted of La recovery as lanthanum oxalate [La2(C2O4)3], using low oxalic acid concentration (0.1 M). The results indicate high La recovery (99.7%)with very high purity (99.9%)when applied on the solution pre-purified and free of Al. Results strongly demonstrated that the simple and universal approach created is beneficial in terms of high metals recovery and final product quality from spent FCC without the need of highly concentrated chemicals and time-consuming processes.