Continuous preparation of pure metals by hydrogen reduction

Claim 2

A process as defined in claim 2 wherein prior to charging the solution to the tubular reactor, free ammonia is incorporated in the solution in a mol ratio to the ions of the copper metal to be recovered of from about 0.1:1 to about 1.6:1.

Claim 3

A process as defined in claim 1 wherein the tubular reactor has a length to diameter ratio of at least 10:1.

Claim 4

A process as defined in claim 1 wherein the solution and hydrogen and any necessary particulate catalyst are charged to the reactor at ambient temperature, and a constantly increasing thermal gradient is maintained in the reactor during its steady state operation from its inlet end to its outlet end.

Claim 5

A process as defined in claim 1 wherein the tubular reactor is operated isothermally over its length at a temperature exceeding 200*F.

Claim 6

A process as defined in claim 5 wherein the temperature within the reactor near its discharge end exceeds about 400*F.

Claim 7

A process as defined in claim 1 wherein the total pressure in the reactor is from about 250 psig. to about 600 psig.

Claim 8

A process as defined in claim 3 wherein said mol ratio of ammonia to copper ions is from about 0.5:1 to about 1.5:1.

Claim 9

A process as defined in claim 1 wherein leaching of said raw material results in the formation of ferrous sulfate in the pregnant leach solution and said raw material contains copper and a metal selected from the group consisting of nickel and cobalt; and wherein said process is further characterized by the additional steps of adjusting the reaction mixture residence time and flow rate, and pH and free ammonia content of the solution, to remove a major portion of the copper value from the solution by hydrogen reduction in the tubular reactor, while allowing a major portion of the nickel or cobalt compounds to remain in solution; then adjusting the pH of the pregnant leach solution to a value of from about 7 to about 12, and adjusting the free ammonia to cobalt or nickel mol ratio to a value of from about 1.5:1 to about 6:1; and passing the adjusted pregnant leach solutions continuously through a second tubular reactor concurrently with hydrogen gas is modified plug flow under steady state conditions to precipitate metallic nickel or cobalt therefrom.

Claim 10

A process as defined in claim 3 wherein the leaching of the raw material is carried out using an aqueous sulfuric acid solution.

Claim 11

The process as defined in claim 11 and further characterized by the steps of: treating the effluent mixture discharged from the reactor to regenerate ammonia and sulfuric acid from ammonium sulfate contained in the effluent mixture; then recycling the ammonia to the free ammonia incorporation step; and recycling the sulfuric acid to the ore leaching step.

Claim 12

The process defined in claim 10 wherein the tubular reactor has a length to diameter ratio of at least 10:1.

Claim 13

A process as defined in claim 11 wherein the solution and hydrogen are charged to the reactor at ambient temperature, and a constantly increasing thermal gradient is maintained in the reactor from its inlet end to its outlet end.

Claim 14

A process as defined in claim 14 wherein the maximum temperature within the reactor exceeds 400*F, and the minimum total pressure in the reactor is at least 350 psig.

Claim 15

A process as defined in claim 15 wherein said mol ratio of ammonia to copper ions is from about 0.5:1 to about 1.5:1.

Claim 16

A process as defined in claim 3 wherein the leaching of the raw material is carried out using an aqueous ammoniacal solution.

Claim 17

A process as defined in claim 1 wherein said tubular reactor extends vertically.

Claim 18

A process as defined in claim 1 wherein said metal to be recovered is nickel or cobalt, and wherein the pH of said pregnant leach solution is adjusted to from about 7 to about 12, and the free ammonia to metal ion ratio thereof is adjusted to from about 1.25:1 to about 6:1, and a catalyst active in the heterogeneous hydrometallurgical reduction of the metal to be recovered is added to said pregnant leach solution.

Claim 19

A process as defined in claim 19 wherein the added catalyst is ferrous sulfate.

Claim 20

A process as defined in claim 20 wherein ferrous sulfate catalyst is added to the pregnant leach solution in an amount of from about 0.25 grams per liter to about 5 grams per liter.

Claim 21

A process as defined in claim 19 wherein the mol ratio of free ammonia to metal ion in the leach solution is adjusted to from about 1.5 to about 2.5.

Claim 22

A process as defined in claim 1 wherein said metal to be recovered is silver, and the free ammonia to silver ion ratio of the pregnant leach solution is adjusted to from 0 to about 4.5.

Claim 23

A process as defined in claim 23 wherein the maximum temperature in the tubular reactor is from about 200*F to about 600*F.

Claim 24

A process as defined in claim 23 wherein said mol ratio is from about 1 to about 3.

Claim 25

A process for continuously hydrometallurgically reducing copper ions in an aqueous solution to copper metal comprising: placing free ammonia in the solution in an ammonia to copper metal ion mol ratio of from 0.5:1 to about 1.5:1; continuously advancing through a fixed tubular reactor the free ammonia containing solution and hydrogen gas in intimate admixture with each other from one location in the reactor where the mixture is at ambient temperature to another location in the reactor where the mixture is heated to at least 200*F while agitating the mixture without homogenizing it over its path of travel during the advance, such advance being at a rate, and agitation being of a magnitude, sufficient to entrain solid particles of an ammonia-copper ion complex formed therein and sufficient to agitate the solution to a state of modified plug flow in which localized, limited back-mixing occurs; and adjusting the distance dimension of the advance to allow a major portion of the copper ions in the solution at the beginning of thE advance to be precipitated as copper metal.

Claim 26

A process for recovering from an aqueous solution, a high purity metal, selected from the group consisting essentially of copper, nickel and cobalt, said process comprising: dissolving inorganic salts of the metal values to be recovered in an aqueous solution; adjusting the pH of the metal salt containing aqueous solution to a value not exceeding 7; then continuously charging the solution to a tubular reactor concurrently with hydrogen gas, and moving the solution and hydrogen gas concurrently through the length of the reactor under substantially steady state conditions and at a rate to entrain and carry through the reactor, solid particles precipitated out of solution during transit of the tubular reactor, the mixture being heated to a temperature of at least 200*F prior to passing out of the discharge end of the reactor and passing from the reactor at a temperature in excess of 200*F, the quantity of hydrogen gas being passed through the reactor concurrently with the solution being in excess of that required for stoichiometric reduction of the metal values to be recovered, and sufficient in quantity and flow rate to agitate the solution to a state of modified plug flow in which localized, limited backmixing occurs, and in which the solution is of heterogeneous character over the length of the reactor; then separating the metal powder from the effluent mixture discharged from the reactor.