Research On The Copper Recovery From WPCBs With Acidithiobacillus Ferrooxidans By Column Leaching System And Its Closed Circuit Circulation Process

The high recovery value of copper and the potential hazards of harmful substances in Waste Printed Circuit Boards?WPCBs?make it extremely important for them to be recycled.Among treatment methods,biological methods is competitive for its green and economic advantages.According to the research results of biological methods in the recycling of WPCBs,combined with the latest research of Cu recovery in the WPCBs leaching water,a column leaching device was emploeed to explore the Cu recovery from WPCBs by Acidithiobacillus ferrooxidans?A.ferrooxidans?and its Closed Circuit Circulation Process.Conclusions have been draw as follows.In the column leaching system,maintaining the pH=2.2 of leachate was conducive to the maintainance the Fe²⁺form,the growth of A.ferrooxidans,and Cu leaching into the leachate as well.Leachate flow rate of 20 mL/min contributed to Cu leached into leaching water more than flow the rate of 40 m L/min did.Based on the above results,column leaching system was adjusted to leach Cu from the WPCBs into leaching water for intermittent 40 h.And finally concentration of Cu in leaching water reached to 8673 mg/L.The process realized the resource treatment of WPCBs by single batch of 1000 g WPCBs granules.Using ozone to reduce the concentration of TOC in the leachate facilitated electrodeposition recovery of Cu in the leachate.Ultrasonic and 45°C water bath temperature environment were set to lower the TOC concentration ozone.And finally,TOC reduced to 408.86 mg/L with remove rato of 42.89%.The result of electrodeposition ways to recover Cu from leaching water was affected by the electrode material and current density.The Cu recovery efficiency rato of 93.29%was achieved within 5 h,with cathode plate material by Carbon felt,anode material by titanium alloy plate and current density by 250 A/m².Ultrasonic and 45°C water bath temperature environment were set to treat the leaching water after the Cu electrodeposition process,and the final TOC concentration of leaching water lowered to 283 g/L.The above process realized the recovery of Cu from the WPCBs bioleaching water and the treatment of WPCBs bioleaching water.After the leachate leached out Cu from WPCBs by columnleaching device and the leachate was treated with ozone,the Cu in the leachate was recovered by the electrodeposition technique,which achieved the recycling of Cu in the WPCBs.After the leachate recovered Cu was treated with ozone and 4.5K mediumwasadded,adding the bacteria to culture can make the leachate reuse in column leaching procedure.The above process finally achieved recycling of WPCBs by A.ferrooxidans in a closed loop process.After accounting for the economic costs of the Cu leaching process and the leachate treatment process,the economic benefits of the process were promising.