TY - BOOK

T1 - Structure and Casting Technology of Anodes in Copper Metallurgy

AU - Wenzl, Christine

N1 - no embargo

PY - 2008

Y1 - 2008

N2 - Anode casting is the link between copper pyro- and hydrometallurgy. To achieve good electrorefining performance, the anodes must have a certain chemical and physical quality. The latter is directly linked with the anode casting process. The aims of anode casting-high output and long mould lifetimes-are not consistent with the objectives of electrorefining, which include uniform dissolution, minimum anode scrap, optimum current efficiency, and high cathode quality. The elemental distribution and the grain size can be adjusted by altering the solidification conditions, for example change of cooling rate, thermal conductivity (i.e., material) of the anode moulds, and mould preheating. Faster cooling leads to finer grains and supersaturated solid solutions. The anode cooling and solidification conditions were determined from mould temperature measurements. To investigate the influence of the casting process on solidification, cooling conditions, and anode quality, the process parameters mould material and mould wash were varied. The casting process at Montanwerke Brixlegg AG and the corresponding anode samples were investigated in detail to establish the reasons for different anode qualities and their effects on electrorefining. The use of different mould materials and mould wash, as well as the different mould lifespan, resulted in significant differences in mould temperature and hence anode cooling conditions. However, these temperature variations did not seem to have an influence on chemical anode quality, but on physical quality. The anodes, which were produced with barite as mould wash, showed a typical cast structure. Variations in structure were detected in the different anodes, namely across the anode thickness and over the anode area, which indicated different local cooling conditions. The cooling was found to be very important, not only regarding anode quality but also regarding mould life and casting rate. As there were no differences across the anode thickness due to chemical quality, the inhomogeneous anodic dissolution behaviour might be caused to a great extent by structural differences across the anode thickness. Potential measurements demonstrated the different dissolution behaviours across the anode thickness. A simulation of the anode casting process was carried out and a basic model for anode solidification developed by using the experimental temperature data. The basic model showed realistic results and can be used for the optimization of the casting system, the cooling arrangement, and the mould design.

AB - Anode casting is the link between copper pyro- and hydrometallurgy. To achieve good electrorefining performance, the anodes must have a certain chemical and physical quality. The latter is directly linked with the anode casting process. The aims of anode casting-high output and long mould lifetimes-are not consistent with the objectives of electrorefining, which include uniform dissolution, minimum anode scrap, optimum current efficiency, and high cathode quality. The elemental distribution and the grain size can be adjusted by altering the solidification conditions, for example change of cooling rate, thermal conductivity (i.e., material) of the anode moulds, and mould preheating. Faster cooling leads to finer grains and supersaturated solid solutions. The anode cooling and solidification conditions were determined from mould temperature measurements. To investigate the influence of the casting process on solidification, cooling conditions, and anode quality, the process parameters mould material and mould wash were varied. The casting process at Montanwerke Brixlegg AG and the corresponding anode samples were investigated in detail to establish the reasons for different anode qualities and their effects on electrorefining. The use of different mould materials and mould wash, as well as the different mould lifespan, resulted in significant differences in mould temperature and hence anode cooling conditions. However, these temperature variations did not seem to have an influence on chemical anode quality, but on physical quality. The anodes, which were produced with barite as mould wash, showed a typical cast structure. Variations in structure were detected in the different anodes, namely across the anode thickness and over the anode area, which indicated different local cooling conditions. The cooling was found to be very important, not only regarding anode quality but also regarding mould life and casting rate. As there were no differences across the anode thickness due to chemical quality, the inhomogeneous anodic dissolution behaviour might be caused to a great extent by structural differences across the anode thickness. Potential measurements demonstrated the different dissolution behaviours across the anode thickness. A simulation of the anode casting process was carried out and a basic model for anode solidification developed by using the experimental temperature data. The basic model showed realistic results and can be used for the optimization of the casting system, the cooling arrangement, and the mould design.

KW - Kupfer

KW - Anode

KW - Anodenkupfer

KW - Anodenguss

KW - Elementverteilung

KW - Gefüge

KW - copper

KW - anode

KW - anode copper

KW - anode casting

KW - elemental distribution

KW - structure

M3 - Doctoral Thesis

ER -