Noranda Inc.

George Houlachi

M Barakat Janjua

Frank Kitzinger

Rodney L LeRoy

Vladimir M Labuc

Gregory A Wint

Carole Allen

Lucy Rosato

Francis Belanger

Terry J Murphy

Jean-Pierre St-Onge

Gary Monteith

Daniel Daoust

The present invention relates to an apparatus for removing volatile impurities such as mercury and selenium from a weak acid solution resulting from scrubbing gases created in the production of sulfuric acid by roasting of sulfide concentrates. The apparatus comprises a calcine filtering unit for removing calcine from the weak acid solution, a sodium sulfide mixing unit for precipitating mercury from the weak acid solution, a sodium dithionite mixing unit for precipitating selenium from the weak acid solution, and a mercury-selenium filtering unit for filtering the precipitated mercury and selenium from the weak acid solution. The present invention further relates to a treatment plant utilizing such an apparatus, a process for removing volatile impurities from a weak acid solution, and a selenium cake obtained by utilizing the resent invention.

Process for reducing selenium and mercury from aqueous solutions

A method and an apparatus for on-line monitoring the quality of a purified metal sulphate solution is disclosed. The method comprises the steps of depositing metal from the purified metal sulphate solution onto a working electrode submerged in the solution by passing constant current through the solution at a current density in the range of 25 to 150 mA/cm.sup.2 for a predetermined time interval, dissolving the metal deposited on the working electrode by reversing the polarity of the potential applied between the working electrode and a counter electrode so as to pass a reverse current of the same current density through the solution until all zinc is removed from the working electrode as sensed by a sudden change in electrode potential, deriving the quality index of the solution by calculating the ratio of the dissolution time over the deposition time, and restoring the surface of the counter electrode by effecting the dissolution of the metal deposited on the counter electrode at the end of each measurement.

Method and apparatus for on-line monitoring the quality of a purified

A method of removing zinc from galvanized steel, comprises immersing the galvanized steel in a caustic electrolyte solution, electrically connecting the steel to the positive terminals of a source of direct current, and electrically connecting the negative terminals of the current source to a cathode material which is stable in caustic electrolyte and has a low hydrogen overvoltage.

Power assisted dezincing of galvanized steel

A process for recovery of copper from a copper residue obtained during purification of a zinc sulfate solution comprises leaching the copper residue in a concentrated sulfuric acid solution in the presence of an oxidant at a temperature of between 60.degree. and 80.degree. C. and separating the solids from the leach solution, electrowinning copper from the leach solution, returning the electrolyte solution to the initial leaching stage to initiate dissolution of the copper residue, and bleeding a portion of the electrolyte solution to reduce the concentration of impurities in the solution.

Process to recover pure copper during purification of zinc sulfate

A chemical treatment of an aluminum cathode used in zinc electrowinning consists of contacting the affected areas of the aluminum cathode or the entire surface of the cathode with a dilute hydrochloric acid aqueous solution.

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Kirkland, Canada

George Houlachi