Study on the cyclic leaching performance of lead sulfate from waste lead paste by triethylene tetramine

The recycling of waste lead paste is the focus of the lead recycling industry. Traditional fire smelting has issues with high energy consumption and heavy pollution. Wet conversion is a green and low-carbon recycling technology for waste lead paste, but its leaching efficiency and recycling of leaching agent need further improvement. In this study, triethylenetetramine (TETA) was used as a leaching agent to investigate the cyclic leaching of PbSO_4 from waste lead paste. An effective leaching model was established using the response surface method, and the leaching reaction parameters were optimized. With a n(TETA/PbSO_4) ratio of 1.3, a reaction time of 11 minutes, a liquid-solid ratio of 2, and a reaction temperature of 30 ℃, the predicted leaching rate of PbSO_4 was 99.99%, achieving an actual leaching rate of 99.93%. The apparent activation energy of PbSO_4 leaching reaction was found to be 47.5 kJ/mol. Furthermore, high-purity PbCO_3 with an impurity content of 0.020 4% could be obtained from TETA-Pb solution by using Na_2CO_3. This process allows for the regeneration cycle of TETA while maintaining a leaching rate of PbSO_4 above 90% in 10 cycles. The results provide a reference for the high-value utilization of waste lead paste.