A pilot-scale trial of an improved galvanic deoxidation process for refining molten copper

Abstract

A laboratory-scale galvanic deoxidation technology developed by earlier workers has been improved, with the aim of developing a prototype pilot-scale deoxidation unit. Each deoxidation cell consists of a one end-closed yttria-stabilized zirconia (YSZ) tube coated with a Ni-YSZ cermet anode on the inner walls. The YSZ tube is immersed, with its closed end in the metallic melt, and an oxygenchemical-potential gradient across the tube is established by passing a reducing gas through the tube. The melt is then deoxidized by short circuiting it with the anode. Through laboratory experimentation, the nature of the anode/electrolyte interface adhesion was identified to be an important factor in obtaining enhanced deoxidation kinetics. The kinetics of oxygen removal from the melt was increased by an order of magnitude with an improved anode/electrolyte interface. A pilot-scale refining unit consisting of 53 cells with the improved anode/electrolyte interface was manufactured, and a field evaluation of the galvanic deoxidation of copper was conducted. The deoxidation-process model was modified to include multiple deoxidation cells, which were required for the pilot-scale trials, and to analyze the effect of electrolyte/electrode adhesion on deoxidation kinetics. Preliminary studies on process component lifetimes were conducted by investigating the thermal cycling, corrosion behavior of the electrolyte, and stability of the cermet anode structure. Based on the results of the field trial and the analyses of the process component lifetime, future work needed toward commercializing the technology is discussed.

Effect of Applied Voltage on Electroreduction with Controlled Oxygen Flow of Molten Slag Containing FeO at 1723 K

“…In other applications, a dynamic mode of operation is employed and the close circuit current or voltage is measured as a function of time. Cells operating in this manner have been used in such applications as diffusion coefficient measurements [29][30][31][32][33] and electrolysis with COF which includes electrolytic refining of molten metal [34][35][36][37][38][39][40][41][42][43] and the above mentioned extraction of metal from molten salt systems. [9][10][11][12][13][14]44,45) However, little work has been done on extraction of metal from high-temperature molten oxide systems.…”

Electrochemical Characterization of a Solid Oxide Membrane Electrolyzer for Production of High-Purity Hydrogen

“…The open-circuit potential of the SOM electrolyzer when a reductant is used at the anode is given by [6,18] …”

“…[17] and Eq. [18] into Eq. [16], the cathodic concentration polarization can be expressed as follows:…”

Electrochemical Deoxidation of Molten Steel with Application of an Oxygen Permeable Membrane

“…The coating method employed in this study is similar to that in other studies. [6][7][8][9]20,21) For comparison, YSZ tube without coating is also used in deoxidation experiment. The YSZ tube is connected to an alumina tube with a ceramic adhesive.…”

“…Thus, electrochemical deoxidation has been proposed by several researchers in order to produce clean metals without inclusions. [1][2][3][4][5][6][7][8][9] Electrochemical deoxidation of liquid steel, which utilizes an oxygen-permeable membrane in the deoxidation process, eliminates the formation of solid inclusions from the beginning. It has started from the idea that oxygen can be removed from the steel melt to deoxidation agents without producing non-metallic solid inclusions under the oxygen chemical-potential gradient (Dm O 2 ) between two sides of the membrane.…”