Remoção de lítio e manganês de pilhas do tipo botão/moeda

Abstract

Lithium button cells are widely daily used due the compact format and high energy capacity. However, the growing demand implies an increase in electronic waste generated by the sector, causing environmental problems and waste of valuable materials due to the lack of recycling processes for batteries. It is known that lithium is an essential material for the energy sector, as it is used as a raw material for batteries with the most diverse formats and charges. Thus, one has a high added value. Thereby the present work sought to recover the metals lithium and manganese present in button-type batteries and evaluate the potential of soy molasses and lignin as reducing agents under optimized recovery conditions. Citric acid, aqua regia, hydrochloric acid, and lactic acid were tested as leaching solutions, with citric acid being the one with the best results. A Central Composite Design (DCC) for the variables battery dust mass, temperature, and citric acid concentration was carried out, which varied according to range 0,06 to 0,74 g, 30 to 130 °C and 0 to 3 M, respectively. Through the results by DCC, it was possible to determine the system's regression equations and evaluate the conditions for the studied variables that maximized the responses of manganese and lithium recovery. The selected conditions were powder mass of 0.233 g, temperature of 80 ºC, and citric acid concentration of 1.5 M. The obtained models were validated by carrying out experiments in the maximized condition of the variables and got recovery 96,33 ± 3 % of Li and 73,64 ± 1 % of Mn. According to Levene and Tukey tests, the use of lignin, soybean molasses, and ultrasound at optimization point did not show considerable increases in the leaching process in the recovery of metals.