Method for recovering lead oxide from waste lead paste

A method for recovering lead oxide from pre-desalted lead paste, comprising the following steps:

• a. dissolving pre-desalted lead paste with a complexing agent solution, so that all PbO in the pre-desalted lead paste reacts with the complexing agent to generate lead complexing ions and thereby obtain a lead-containing solution and a filter residue, wherein the PbO originates from the PbO in the pre-desalted lead paste and PbO generated in a reaction between the Pb and PbO2 from the pre-desalted lead paste in the complexing agent solution and further includes PbO obtained from oxidation of the Pb in the pre-desalted lead paste or from reduction of the PbO2 in the pre-desalted lead paste, and wherein the complexing agent is a compound having amino and carboxyl groups, an organic amine, an alcohol amine or salts thereof;
• b. adding a precipitant into the lead-containing solution, so that the precipitant reacts with the lead complexing ions to generate a lead salt precipitate and a regenerated complexing agent, wherein, the precipitant is gaseous CO2, SO2, SO3 or a water solution thereof;
• c. calcining the lead salt precipitate to obtain lead oxide and regenerate the precipitant.