Method of pyrolysis for waste light-emitting electronic components and recovery for rare-earth element

A method of pyrolysis for waste light-emitting electronic components and recovery for rare-earth element, comprising:

• step 1:
• using a steel belt continuous pyrolysis furnace to pyrolyze waste light-emitting electronic components, wherein N2 is introduced into the steel belt continuous pyrolysis furnace as a protective gas, oil-gas mixture and residue are obtained by heating and pyrolysis;
• initial temperature of the pyrolysis is 300-400° C., end temperature of the pyrolysis is 500-650° C.;
• 3-stage zone temperature control heating is adopted, temperature of zone 1 is 300-400° C., temperature of zone 2 is 400-550° C., temperature of zone 3 is 500-650° C., and pyrolysis time is 90-150 min;
• step 2:
• the residue with residual heat is sent, under protection of N2 atmosphere, to a gas generator, and high-temperature water vapor is introduced to convert carbon in the residue into water gas to obtain pyrolysis residue;
• temperature of the high-temperature water vapor is 750-900° C., reaction pressure is 2.3-3.2 MPa, and reaction time is 3-5 min;
• step 3:
• the oil-gas mixture is sent to a spray condensing tower, HBr is removed by lye spray and oil and gas are separated, pyrolysis oil, pyrolysis gas and NaBr are obtained;
• step 4:
• phosphor powder in the pyrolysis residue and metals in the pyrolysis residue are separated by eddy current separation, and acid leaching solvent and acid leaching auxiliary solvent are added to the phosphor powder to conduct acid leaching reaction;
• filtrate 1 and filter residue 1 are obtained by filtration;
• step 5:
• adding alkali melting agent to filter residue 1, performing an alkali melting process to obtain an alkali melting product;
• then adding acid leaching solvent and acid leaching auxiliary solvent to the alkali melting product to carry out acid leaching treatment, phosphor powder of nitrogen oxide system and phosphor powder of garnet system are leached, and filtrate 2 containing Eu3+, Tb3+ and Ce3+ is obtained by filtration;
• in the alkali melting process, a mass ratio of filter residue 1 to the alkali melting agent is 1:2-1:6, calcination temperature is 600-1000° C., and calcination time is 30-60 min;
• step 6:
• mixing filtrate 1 and filtrate 2 to obtain a mixed solution, adding a dispersant to the mixed solution, stirring and mixing;
• adding an oxalic acid solution to the mixed solution, then adding ammonia water to the mixed solution to obtain a final solution, wherein pH of the final solution is adjusted to 1.8-2.0 with the ammonia water, and the final solution is settled at 23-28° C. for 4-6 hours;
• after the settling of the final solution is complete, precipitation is filtered, washed, and dried by heat from a flue gas boiler to obtain rare earth oxalate.