Study On The New Technology Of Ultrasonic Enhanced Treatment Of Complex Materials Containing Zinc And Indium

Intermediate by-products generated in the process of zinc hydrometallurgy, contains a large amount of zinc, lead, copper and other valuable metals, and most of them also contain associated rare metal indium, so they are quite of value, can be seen as the main raw material of recovering zinc and indium. At present, they are mainly treated by the rotary kiln reductive roasting united with acid leaching or the unique acid leaching process.Since the intermediate by-products are of complex components, resulting in many problems existed in the traditional acid leaching process. In this paper, with zinc oxide flue dust and secondary zinc oxide powder leaching residue as raw materials, considering the insoluble lead sulfate and gangue usually concentrated on the surface of solid particles as coating layers, which could be a hinder for the leaching reaction, the ultrasonic technology was introduced into the zinc and indium recovery process, as the cavitation effect produced by the ultrasound could break the coating layers. Compared to the conventional leaching, with the assist of ultrasound, the reaction time could be greatly shortened and the metal could be more efficiently recovered, thus the ultrasonic technology is of bigger advantage, and the main research results are as follows:1. With zinc oxide flue dust as raw material, both the conventional and ultrasound-assisted leaching experiments were carried out. Among them, in the neutral leaching stage, under the conventional leaching conditions, as the liquid to solid ratio of 5:1, reaction temperature of 50 ℃ and the reaction time of 60min, the leaching rate of zinc and indium reached 76.72% ,6.54%, respectively. Under the ultrasound-assisted leaching conditions, as the solid ratio of 5:1, reaction temperature of 35℃, ultrasonic power of 540W and the reaction time of 20min, the leaching rate of zinc reached 78.05% and of indium was 9.00%. While the leaching rate of zinc increased by 1.33%, the temperature reduced by 15℃, the time shortened by 66.7%. In the acid leaching stage, as the initial sulfuric acid concentration of 140g/L, reaction temperature of 80℃, the ratio of solid to liquid of 5:1, leaching time of 75min, and ultrasonic power of 1440W, the leaching rate of zinc was 74.54%, of indium reached 84.72%, which proved that the reaction time reduced by 37.5%, and the leaching rate of zinc and indium increased by 2.57%,5.93%, respectively, compared to leaching for 120min without ultrasound. Therefore, assisted by ultrasound, not only the leaching recovery of zinc and indium were improved, but also the reaction time was greatly shortened, and the reaction temperature was lowered.2. With secondary zinc oxide powder leaching residue as raw material, both the conventional and ultrasound-assisted leaching experiments were carried out. Under the conventional leaching conditions, as the initial sulfuric acid concentration of 150g/L, the ratio of solid to liquid of 6:1, reaction temperature of 80℃, and the leaching time of 120min, the leaching rate of zinc and indium reached 78.68%,79.70%, respectively; Under the ultrasound-assisted leaching conditions, as the initial sulfuric acid concentration of 150g/L, the ratio of solid to liquid of 5:1, reaction temperature of 70℃, and the leaching time of 90min, the leaching rate of zinc and indium reached 79.62%,80.12%, respectively. Therefore, assisted by ultrasound, not only the leaching recovery of zinc and indium were improved, but also the reaction time was shorten by 25%, and the reaction temperature was reduced by 10℃.