Capabilities
- Can reduce returned zinc electrolyte to less than 1 ppm of iron in sulfate bath
- Volume of zinc electrolyte lost unit weight of iron is less than 0.1 gallons/lb or iron removed
- Can remove iron without removal of significant amounts of nickel or cobalt
- Total automation with exception of unloading filter press
- Automated zinc oxide and diatomaceous earth handling
- Oxidation-reduction potential control of hydrogen peroxide addition
- Flow rates up to 20 gpm
Description of process
- Iron laden zinc electrolyte is added to the first reaction vessel
- Ferrous iron is oxidized to ferric iron with the following reactants:
- zinc oxide
- hydrogen peroxide
- Above reactions are slow; equipment is designed to keep from overshooting reactant addition
- Diatomaceous earth is added for intimate mixing with the ferric hydroxide particulate formed
- Solution is filtered though high press filter press
- Optional membrane filter plates allow zinc electrolyte to be washed from iron oxide cake before discharge
Above process has been installed and operating at a major North American electro-galvanizer since 1995
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