Exxon Research and Engineering Company

James E Hoffmann

John S Batzold

Kohur N Subramanian

The present invention contemplates treating a zinc sulfate containing solution, especially a neutral leach filtrate with a reducing agent selected from ZnSO.sub.3, SO.sub.2 or mixtures thereof to substantially reduce the oxidant therein and to obtain a solution having a predetermined pH. Thus, in one embodiment of the present invention, a neutral leach filtrate containing an oxidant selected from permanganate and manganate ions and mixtures thereof is treated with a reducing agent selected from ZnSO.sub.3, SO.sub.2 or mixtures thereof in amounts sufficient to substantially reduce all the manganese ions present (permanganate and/or manganate) to the divalent state and to provide a zinc sulfate solution for electrodeposition of the zinc having a predetermined pH.

Process for reducing Zn consumption in zinc electrolyte purification

The present invention contemplates providing a finely divided copper calcine and thereafter subjecting the calcine to reduction flash smelting. Indeed, significant processing advantages are achieved by dead roasting a finely divided copper concentrate, especially in a fluid bed reduction zone, and thereafter subjecting the resulting calcine to reduction flash smelting. Gases from the dead roaster and the flash smelter are combined for SO.sub.2 recovery in an acid plant.

Dead roast-oxide flash reduction process for copper concentrates

The present invention is predicated upon the discovery that in the electrowinning of copper from solutions thereof, a hydrogen fed porous catalytic anode can be caused to operate under such conditions of constant current flow whereby a dynamic equilibrium will be imposed upon the hydrogen fed anode so that the anode will behave as a normal copper anode in a refining mode. This is particularly true when such a hydrogen fed anode is deactivated by copper buildup on the surface of the electrode.

Growing community of inventors

South Plainfield, NJ, United States of America

James E Hoffmann