NOVEL DSA~? ANODE FOR ELECTROWINNING OF NON-FERROUS METALS

摘要

The result of extensive research into fundamental mixed metal oxide catalyst morphology has produced a next generation all titanium DSA~? anode. This new DSA~? anode, patent pending, is tailored for electrowinning of non-ferrous metals (copper, nickel, cobalt, zinc) by means of this new coating technology, already utilised in the chlor-alkali world. These DSA~? anodes are characterised by a hanger bar with vertical distributor bars, having primary titanium mesh attached by weldments. The active mesh is provided with noble-metal electrocatalytic coatings, consisting of iridium and/or ruthenium oxides, obtained by thermal decomposition of precursor solutions applied to the titanium substrates. The catalytic activity of state-of-the-art DSA~? anodes is improved by about 80 mV by controlling the crystallite size of the noble-metals without decreasing the decomposition temperature. It is known that below a certain value (typically 400°C) the stability of these oxides, and associated lifetime, is seriously compromised. A highly active DSA~? anode, consisting of a quasi-amorphous phase, is obtained at high temperature (above 450 °C), therefore not compromising lifetime performance. Through optimisation of these design parameters, the manufacture of these novel anodes was identified. DSA~? anodes performance advantages include: lead-free 'green' all titanium anodes, true lead-free cathode quality, energy savings of 0.3 to 0.55 V can be realized depending on the EW application when compared to industry standard lead-alloy anodes, sustainability designed into long-life recoatable anode structures, increase plant cathode output through increased current density operations, eliminate need for cobalt sulphate addition required for lead anodes, improved plant on-stream production, no sludge generated or removed, and improved current distribution producing smooth high efficiency cathode.