Gerardo Cifuentes

COPPER ELECTROWINNING BASED ON REACTIVE ELECTRODIALYSIS

This paper shows an alternative to the classic electrowinning copper process using a cell based on reactive electrodialysis, which consists of two compartments separated by an anionic membrane, one of which contains the copper sulphate catholyte, where the cathode is located, and the other compartment contains the ferrous sulfate anolyte, where the anode is located. In this type of cell the anodic reaction is the oxidation of iron (Fe2+ to Fe3+), which consumes less energy than the classic water oxidation. Moreover, this new anodic reaction does not produce acid mist.

ANODIC ELECTROLYTIC DISSOLUTION OF COPPER SULPHIDES PRECIPITATED FROM AMMONIACAL LEACHING MEDIA

Anodic dissolution of synthetic chalcocite (previously obtained by copper precipitation with S and SO 2 in ammonia media) in two different electrolytic cells is described. One cell has a circular graphite anode placed horizontally, surrounded by a stainless steel cylinder as cathode, and the other has a rectangular basketshaped graphite anode, with a rectangular stainless steel cathode placed in front of it. The electrolysis was performed at 0.2 A and 50 °C, the electrolyte contained 20 to 40 g L-1 of Cu and 100 to 160 g L-1 of H 2 SO 4 , and the initial reactions took place at low potential (0.4-0.6 V) until the transformation of Cu 2 S into CuS, detected by the considerable increase in cell potential. Anodic and cathodic efficiencies greater than 100% and 95%, respectively, were obtained. The hight anodic efficiencie is due to faradic and chemical dissolution too. It is also shown that the (CuS) produced as waste material can replace elemental sulphur as copper precipitating agent in ammoniacal media.

Recovery of hydrochloric acid from ion exchange processes by reactive electrodialysis

The purification process of electrolytes contaminated from electrorefining consists in placing them in contact with an ion exchange resin which can function continuously due to its reconditioning with hydrchloric acid. The treatment of the resultant solution, known as elution, consists in doing a fractional distillation releasing hydrochloric acid and gaseous chlorine. The release of these represents most of the operational problems in the electrolyte treatment plant. This paper proposes an alternative to this distillation process, using a reactive electrodialysis cell and cation and anion exchange membranes.

ZINC ELECTROWINNING USING REACTIVE ELECTRODIALYSIS (RED)

ABSTRACT This paper presents an alternative process for the conventional zinc electrowinning, which consists of a cell of two compartments separated by a anion exchange membrane.One of them contains a zinc sulphate catholyte and sulfuric acid while the anolyte solution contains ferrous sulfate and sulfuric acid.By using a membrane the classical lead anode may be replaced, as well as the main oxidation reaction of water, for that of the ferrous ion to ferric ion.This leads to significant savings in specific energy consumption of the overall process and eliminates the classic problem of acid mist in electrowinning cells.The results show that the proposed process consumes 30% less cell potential compared to conventional electrowinning cell. Keywords: zinc, electro-winning, reactive electrodialysis. e-mail:gerardo.cifuentes@usach.cl INTRODUCTION The process of obtaining zinc from zinc sulfide ore consists of 4 stages, according to Figure 1.1: roasting, leaching, purification and electrolysis.

USE OF ELECTRODEPOSITION OF NICKEL IN THE MANUFACTURE OF LEU ANNULAR TARGETS

This work presents the results of a thin electroplated layer of nickel on the surface of the uranium to achieve deposits 15 to 25 μm thick. Ultrasound tests and electron microscopy showed good adhesion and homogeneity of the Ni deposit, which has high hardness and relatively small grain size, with an orientation in the direction of current flow.

An alternative copper electrowinning process based on reactive electrodialysis (RED)

(1) Departamento de Ingeniería Metalúrgica, Facultad de Ingeniería, Universidad de Santiago de Chile, Avenida Libertador Bernardo O’Higgins 3363, Casilla 10233, Fono: 56-2-7183224, Santiago, Chile. E-mail: gerardo.cifuentes@usach.cl . (2) Departamento de Ingeniería Mecánica, Facultad de Ingeniería, Universidad de Santiago de Chile. (3) Departamento de Ingeniería Metalúrgica, Universidad Católica del Norte. Avenida Angamos 0610, Antofagasta, Chile