Intense yet energy-efficient process for electrowinning of zinc in mobile particle beds
First Claim
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1. A method for electrodepositing zinc onto particles in an electrolytic cell from an electrolyte solution containing zinc ion, said electrolytic cell containing a current feeder and a counter electrode with an ion-permeable diaphragm interposed therebetween to define a gap of preselected width between said current feeder and said diaphragm, said method comprising passing a mixture of said particles and said electrolyte solution through said gap while passing a current across said gap, subject to the following limitations:
- (a) for electrolytes containing acid at a concentration of 1.2×
10-2 N or less, a number mean particle diameter ranging from a minimum of 0.3 mm to a maximum of 0.25 times said gap width, and(i) for a gap width of 20 mm or less, a maximum superficial current density equal to 22,000 minus the product of 800 times the gap width; and
(ii) for a gap width greater than 20 mm, a maximum superficial current density of 6,000; and
(b) for electrolytes containing acid at a concentration of from 1.2×
10-2 N to 4.0N, a number mean particle diameter ranging from a minimum of 0.5 mm to a maximum of 0.25 times said gap width, and(i) for a gap width of 20 mm or less, a minimum superficial current density of 80 times the gap width, and a maximum current density equal to 22,000 minus the product of 800 times the gap width; and
(ii) for a gap width greater than 20 mm, a minimum superficial current density of 1,600 and a maximum current density of 6,000;
wherein the gap width is expressed in millimeters, and the superficial current density is defined as the current divided by the projected surface area of the largest of said current feeder and said counter electrode and is expressed in amperes per square meter.
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Abstract
Zinc metal is deposited on mobile seed particles in an electrowinning process. Exceptionally favorable results in terms of production rate, current efficiency and energy consumption are achieved by using a unique combination of design parameters and operating conditions achieved by selected ranges for particle size, current density, particle bed thickness, and acid content of the electrolyte.
59 Citations
20 Claims
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1. A method for electrodepositing zinc onto particles in an electrolytic cell from an electrolyte solution containing zinc ion, said electrolytic cell containing a current feeder and a counter electrode with an ion-permeable diaphragm interposed therebetween to define a gap of preselected width between said current feeder and said diaphragm, said method comprising passing a mixture of said particles and said electrolyte solution through said gap while passing a current across said gap, subject to the following limitations:
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(a) for electrolytes containing acid at a concentration of 1.2×
10-2 N or less, a number mean particle diameter ranging from a minimum of 0.3 mm to a maximum of 0.25 times said gap width, and(i) for a gap width of 20 mm or less, a maximum superficial current density equal to 22,000 minus the product of 800 times the gap width; and (ii) for a gap width greater than 20 mm, a maximum superficial current density of 6,000; and (b) for electrolytes containing acid at a concentration of from 1.2×
10-2 N to 4.0N, a number mean particle diameter ranging from a minimum of 0.5 mm to a maximum of 0.25 times said gap width, and(i) for a gap width of 20 mm or less, a minimum superficial current density of 80 times the gap width, and a maximum current density equal to 22,000 minus the product of 800 times the gap width; and (ii) for a gap width greater than 20 mm, a minimum superficial current density of 1,600 and a maximum current density of 6,000; wherein the gap width is expressed in millimeters, and the superficial current density is defined as the current divided by the projected surface area of the largest of said current feeder and said counter electrode and is expressed in amperes per square meter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Current AssigneePasminco Australia Ltd., Regents of the University of California (University of California)
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Original AssigneeRegents of the University of California (University of California)
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InventorsSiu, Stanley C., Newman, Oliver M. G., Salas-Morales, Juan C., Evans, James W.
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Primary Examiner(s)Gorgos, Kathryn L.
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Assistant Examiner(s)NOGUEROLA, ALEXANDER STEPHAN
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Application NumberUS08/521,021Time in Patent Office643 DaysField of Search205/560, 205/602, 205/603US Class Current205/602CPC Class CodesC25C 1/16 of zinc, cadmium or mercuryC25C 7/002 of cells comprising at leas...
