Estudo dos lixiviantes de rotas hidrometalúrgicas para extração de metais a partir do lixo eletrônico

Abstract

Today, above all, technology has taken root in everyday life. Several tasks and operations are performed by means of machines, from cleaning to feeding, offering comfort, agility and precision. These devices, surrounded by constant improvement, are shaped from innovation and planned obsolescence that collaborate together for the voluminous amount of waste, especially with regard to electronics. Thus, this work aims to study the proportions of extraction of some leachates from hydrometallurgy, and this treatment with leachate is effective for the immense amount of electronic equipment through the recycling of metals, also demonstrating the loss of opportunities that impact society and the environment. The hydrometallurgical process used separated the metals from the waste by digesting the printed circuit board (PCB) material in solutions of aqua regia, nitric acid, sulfuric acid and sulfuric acid added with hydrogen peroxide. In 6 hours of digestion, aqua regia resulted in an average of 25.54%, while nitric acid had an average extraction value of 29.69%. For hydrochloric acid, an average of 1.94% was found and the “piranha” solution expressed an average value of 2.04%. While in 24 hours, the values increased, the aqua regia showed an average of 28.62% while for concentrated nitric acid it had an average value of 34.70%. For hydrochloric acid, the average extraction obtained was 2.63%, and for sulfuric acid in an oxidizing medium, an average of 7.22% extraction was found. Therefore, numerically, the best performance was determined, that is, the nitric acid system in 24 hours. The verification of the influence of agitation occurred in this system and concluded in an average value of 39.90%, that is, an increase of 14.98% in the removal of components, evidencing a positive influence on the leaching procedure. In this study, copper leaching stood out because it was the metal that presented the highest concentrations in any of the procedures performed and the highest extraction results. There are criteria to be considered in the final decision when choosing the appropriate leachate for each laboratory, such as cost, availability of reagents, energy spent when adding agitation, etc. However, numerically and according to the study carried out, the best system for leaching metals contained in PCIs was concluded to be composed of nitric acid as a leaching agent plus constant agitation for 24 hours.