Process for the electrolytic refining of heavy metals

Claim 2

IN A PROCESS FOR REFINING BY CATHODICALLY ELECTRODEPOSITING A HEAVY METAL AT THE CATHODE WHILE SIMULTANEOUSLY EVOLVING AN ELEMENTAL HALOGEN AT THE INSOLUBLE ANODE FROM AN AQUEOUS ELECTROLYTE SOLUTION CONTAINING DISSOLVED THEREIN A HALIDE OF THE HEAVY METAL, THE HEAVY METAL BEING SELECTED FROM THE GROUP CONSISTING OF COBALT, NICKEL, ZINC, IRON, TIN AND MANGANESE, THE IMPROVEMENT WHICH COMPRISES THE PRESENCE IN THE ELECTROLYTE SOLUTION OF A HALIDE OF A SECOND METAL BEING AT THE GROUP CONSISTING ALKALI METAL AND ALKALINE EARTH METAL, THE CONCENTRATION OF THE HALIDE OF THE SECOND METAL BEING AT LEAST ABOUT 60% OF ITS SATURATION CONCENTRATION IN THE ELECTROLYTE SOLUTION, WHEREBY A HARD, DENSE AND SMOOTH DEPOSIT OF THE HEAVY METAL CAN BE DEPOSITED AT THE CATHODE, IN THE ABSENCE OF A BUFFERING AGENT.

Claim 3

The process of claim 1, wherein the heavy metal is nickel.

Claim 4

The process of claim 2, wherein the halide of a second metal is an alkaline earth metal chloride.

Claim 5

The process of claim 3, wherein the halide of a second metal is magnesium chloride.

Claim 6

The process of claim 3, wherein the halide of a second metal is calcium chloride.

Claim 7

The process of claim 2, wherein the halide of a second metal comprises sodium chloride.

Claim 8

The process of claim 2, wherein the halide of a second metal comprises potassium chloride.

Claim 9

A process in accordance with claim 1, wherein the elemental halogen is chlorine.

Claim 10

A process in accordance with claim 8, wherein the halide of the second metal is sodium chloride.

Claim 11

A process in accordance with claim 9, wherein the halide of the heavy metal is nickel chloride.

Claim 12

A process in accordance with claim 9, wherein the halide of the heavy metal is cobalt chloride.

Claim 13

The process of claim 1, wherein the heavy metal is cobalt.

Claim 14

The process of claim 12, wherein the halide of a second metal is an alkali metal chloride.

Claim 15

The process of claim 12, wherein the halide of a second metal is an alkaline earth metal halide.

Claim 16

The process of Claim 12, wherein the halide of a second metal is selected from the group consisting of sodium chloride, magnesium chloride, calcium chloride and potassium chloride.

Claim 17

The process of claim 1, wherein the anode and the cathode are in a single chamber such that there is uninterrupted fluid flow between the anode and the cathode, in the absence of a buffer material in the electrolyte solution.

Claim 18

The process of claim 1, wherein the concentration of the heavy metal in the electrolyte solution is not greater than about 2 gram-atoms/liter of the metal.

Claim 19

The process of claim 1, wherein the pH of the electrolyte solution is maintained substantially constant during electrolysis without the addition of a buffer material.

Claim 20

The process of claim 1, wherein the halide of a second metal is a chloride.

Claim 21

The process of claim 1, wherein the electrolysis is carried out utilizing as the cathode a ''''starter sheet'''' formed of the heavy metal to be plated.

Claim 22

The process of claim 1, wherein the electrolysis is carried out at a temperature of at least about 35*C.

Claim 23

The process of claim 1, wherein the concentration of the heavy metal in the electrolyte solution is in the range of from about 0.3 gm-atoms per liter to about 1.5 gm-atoms/liter.

Claim 24

The process of claim 1, wherein the pH of the electrolyte is in the range of from about 1 to about 3.5.

Claim 25

The process of claim 1, comprising feeding the aqueous electrolyte solution to an electrolyte cell wherein the feed solution is substantially saturated in the neutral source of halide ion.

Claim 26

A process for obtaining an elemental heavy metal from a halide of the heavy metal by cathodically electrodepositing the heavy metal while obtaining an elemental halogen, the process comprising subjecting to electrolysis, between an insoluble anode and a cathode, an aqueous solution comprising dissolved therein a halide of a heavy metal selected from the group consisting of cobalt, nickel, tin, zinc, iron and maganese, to be electrodeposited, and a halide of a second metal selected from the group consisting of alkali metals and alkaline earth metals, the total concentration of halide ion in the aqueous solution being sufficient to eliminate any substantial change in the pH of the aqueous solution during electrolysis without the addition of a buffer solution and being such as to provide a concentration of the halide of the second metal of at least 60% of its saturation concentration in the electrolyte solution, so as to evolve an elemental halogen at the insoluble anode and to deposit elemental heavy metal at the cathode as a dense, smooth and hard deposit.

Claim 27

A process for obtaining an elemental heavy metal from a halide of the heavy metal by cathodically electrodepositing the heavy metal while obtaining an elemental halogen, the process comprising subjecting to electrolysis, between an insoluble anode and a cathode, an aqueous solution comprising dissolved therein a halide of a heavy metal selected from the group consisting of cobalt, nickel, tin, zinc, iron and maganese, to be electrodeposited, and a halide of a second metal selected from the group consisting of alkali metals and alkaline earth metals, the total concentration of halide ion in the aqueous solution being sufficient to eliminate any substantial change in the pH of the aqueous solution during electrolysis without the addition of a buffer solution and being such as to provide a concentration of the halide of the second metal of at least 60% of its saturation concentration in the electrolyte solution, so as to evolve an elemental halogen at the insoluble anode and to deposit elemental heavy metal at the cathode as a dense, smooth and hard deposit.

Claim 28

The process of claim 25, wherein the total concentration of halide ion in the electrolyte solution is at least about 3.6 gram-atom/liter of halide ion.

Claim 29

A process in accordance with claim 25, wherein the elemental halogen is chlorine.

Claim 30

A process in accordance with claim 1, wherein the elemental halogen is selected from the group consisting of chlorine, bromine and iodine.