**Marcelo Rodríguez 1, Luís Ayala 2, Pedro Robles 3,\*, Rossana Sepúlveda 4, David Torres 1,5, Francisco Raul Carrillo-Pedroza 6, Ricardo I. Jeldres <sup>7</sup> and Norman Toro 1,5,\***


Received: 10 December 2019; Accepted: 24 January 2020; Published: 27 January 2020

**Abstract:** The unique properties of ionic liquids (ILs) drive the growing number of novel applications in different industries. The main features of ILs are high thermal stability, recyclability, low flash point, and low vapor pressure. This study investigated pure chalcopyrite dissolution in the presence of the ionic liquid 1-butyl-3-methylimidazolium hydrogen sulfate, [BMIm]HSO4, and a bromide-like complexing agent. The proposed system was compared with acid leaching in sulfate media with the addition of chloride and bromide ions. The results demonstrated that the use of ionic liquid and bromide ions improved the chalcopyrite leaching performance. The best operational conditions were at a temperature of 90 ◦C, with an ionic liquid concentration of 20% and 100 g/L of bromide.

**Keywords:** leaching; chalcopyrite; ionic liquid; bromide
