Direct Current Electrolytic Leaching Gold And Copper From Waste Printed Circuit Board

At present,the disposal of electronic waste has become a global problem.For the resource utilization of the key components of the WPCBs,the key problem is how to reduce and eliminate the secondary pollution caused by the heavy use chemicals and improve the resource recovery rate.From the point of view of green resource utilization,the paper use"Direct current electrolytic"leach the gold and copper from WPCBs.The leaching effect and leaching principle of gold and copper with hydrochloric acid and hydrobromic acid as electrolyte under different conditions were studied.On the basis of the above,the leaching system is further study,and the main work is as follows:?1?Analysis the metal element of WPCBs;The main metal content in WPCBs was determined by ICP-AES,including 0.36mg/g gold and 338.45mg/g of copper.?2?Using HCl+H₂O₂,HCl+DC,HCl+H₂O₂+DC as electrolyte to leach gold and copper from WPCBs,find that the gold leaching effects of HCl+H₂O₂+DC is the best of the three systems and the copper leaching effects of HCl+DC is the best system.After that,single factor experiment was carried out to determine the optimal zero point of the steepest ascent design for HCl+H₂O₂+DC system.Using design-expert to optimize the steepest ascent design to find the optimal condition.Using three levels and four factors to carry out variance analysis and data fitting for the leaching model,and the priority degree of influence of various conditions on the leaching system was obtained.Finally,the mathematical model was used to obtain the optimal leaching effect.Optimal gold leaching conditions is?1cm carbon rod as electrodes,electrode distance extremely 3cm,4.1 Volt DC,40?,hydrochloric acid 8.9 mol/L,acid and oxidant mole ratio is 45,3h,liquid-solid ratio 15:1,700 rpm,and verification optimization experiment three times,the optimal gold leaching rate is 98.87%,the copper leaching rate is 92.1%.Further comparison of gold and copper leaching effects with different additives find that selective leaching of gold and copper could be achieved by selecting different additives.?3?Using HBr+H₂O₂,HBr+DC,HBr+H₂O₂+DC as electrolyte to leach gold and copper from WPCBs,find that the gold leaching effects and copper leaching effects of HBr+H₂O₂+DC is the best of the three systems.After that,single factor experiment was carried out to determine the optimal zero point of the steepest ascent design for the best leaching system.Using design-expert to optimize the steepest ascent design to find the optimal condition.Using three levels and four factors to carry out variance analysis and data fitting for the leaching model,and the priority degree of influence of various conditions on the leaching system was obtained.Finally,the mathematical model was used to obtain the optimal leaching effect.Optimal gold leaching conditions is?1cm carbon rod as electrodes,electrode distance extremely 3cm,2 Volt DC,temperature 23?,hydrobromic acid percentage concentration 8.5%,acid and oxidant mole ratio is 4.3,8.4h,liquid-solid ratio 15:1,700 rpm,and verification optimization experiment three times,the optimal gold leaching rate is 98.43%,the copper leaching rate is 82.35%.?4?Explore the green process of electrolytic leaching gold and copper.Using DBDMH+H₂O₂+DC leaching gold and copper from WPCBs.Find that the gold leaching rate could reach 93.4%under the conditions of 60ml deionized water,0.003mol DBDMH,0.02mol H₂O₂,3V DC,liquid-solid ratio:50:1,0.0024mol NaBr,pH 5.0 and room temperature electrolysis leaching 2d.WPCBs were treated with Gly+H₂O₂+DC in alkaline environment,which had poor effect on gold,only constant gold leaching,but copper glycine was obtained.