Method and system for pyrolytic recycling of mobile phone circuit boards

A method for pyrolytic recycling of mobile phone circuit boards based on a system, the system comprising a feed hopper, a first feeder, a second feeder, a rotary furnace, a pyrolysis gas heating unit, a condenser and a screw discharger, the second feeder being a screw feeder, the feed hopper, the first feeder and the second feeder being arranged sequentially, the rotary furnace being provided with a preheating section, a plurality of heating sections and a cooling section connected in series, the preheating section being arranged upstream of the plurality of heating sections along a conveying direction of the mobile phone circuit boards, the cooling section being arranged downstream of the plurality of heating sections along the conveying direction of the mobile phone circuit boards, the pyrolysis gas heating unit comprising an induced draft splitter, and the method comprising:

• continuously conveying, via the feed hopper, the first feeder and the second feeder, the mobile phone circuit boards into the rotary furnace, wherein each of the plurality of heating sections is set to a temperature of 600-800° C., a pressure inside the rotary furnace is controlled to-50-0 Pa, and a rotational speed of the rotary furnace is controlled to 2-20 r/min;
• performing pyrolysis on the mobile phone circuit boards at the plurality of heating sections of the rotary furnace with a residence time controlled to generate a pyrolysis gas and a pyrolysis residue;
• transporting the pyrolysis gas in a direction opposite to the conveying direction of the mobile phone circuit boards to sequentially pass through the preheating section and the second feeder for cooling, and finally to enter the pyrolysis gas heating unit;
• splitting, via the induced draft splitter, the pyrolysis gas into a first pyrolysis gas part and a second pyrolysis gas part;
• subjecting the first pyrolysis gas part to air-deficient combustion to generate a flue gas;
• mixing the flue gas with the second pyrolysis gas part to form a mixed gas having a temperature of 400-600° C.;
• dedusting the mixed gas, and cooling a dedusted gas to 50° C. or below in the condenser with a 20-40° C. circulating cooling water to collect a condensed pyrolysis oil;
• and transporting a non-condensable residual gas to a waste gas treatment station;
• and
• discharging the pyrolysis residue from the cooling section followed by cooling to 200-300° C. via the screw discharger, crushing and sieving.