Diseño de una planta de recuperación de zinc a partir de los polvos de acería mediante lixiviación con ácido sulfúrico y deposición electrolítica

Abstract

The objective of this project is to design a Zn recovery plant based on steel mill powders from the steel industry. The strategy proposed is H2SO4 leaching and subsequent electrolytic deposition. The plant was designed for a production capacity of 19,43 ton Zn/cycle of process. The design encompasses characteristics of a batch process which consists of five main stages: acid leaching, filtration, pH conditioning, cementation and fusion. In the leaching stage, the steel dust is mixed with a H2SO4 solution with a concentration of 150 g/L until it reaches a solid percentage of 33 %. The filtration stages remove the solid waste and heavy metals from the solution that results from leaching, pH conditioning and cementing. For the electrodeposition, 144 electrolytic cells will be used that will work with a voltage of 4,03 V and a current flux 727 A/m². The cathodic Zn that results from the electrolysis of the solution will enter a refining process that is the fusion in an induction furnace at 550 °C and with NH4Cl as a melting charge. The total yield of the process is estimated in 68 % based on the recovery of Zn, which is 809,716 t Zn/year. With the international price of Zn at USD 2 750 per ton (2017), the project has economic indicators such as the VAN and the IRR of 150 144,85 USD and 19,30 %, respectively, which demonstrate the profitability of the process.