Hydrometallurgical leaching process and apparatus

Claim 2

A process for recovering a metal from a material containing the metal, said metal being selected from the group consisting of gold, uranium, copper, zinc, nickel and lead, and said material being selected from the group consisting of ores, concentrates and calcines, which process comprises: a) introducing an aqueous slurry of particles of said material containing the metal into a leaching zone of a vertical column, the vertical column having a lower leaching zone and an upper clarifying zone, sa id slurry containing an aqueous solution of leaching agent, which is initially saturated with dissolved oxygen, and defining a fluid medium, and said particles of said material containing the metal; b) maintaining a velocity profile in said column spanning said leaching and clarifying zones effective to maintain said particles fluidly suspended in said leaching zone and to promote settling of said porous particles from an upper region of the leaching zone such that said clarifying region comprises an aqueous leachate having not more than 200 mg/l of said particles; and c) withdrawing a metal-containing leachate from the clarifying zone.

Claim 3

The process of claim 1, wherein said velocity profile is such that the clarifying zone comprises an aqueous leachate having not more than 100 mg/l of said particles.

Claim 4

The process of claim 1, wherein said slurry is substantially free of undissolved gases.

Claim 5

The process of claim 1, wherein said slurry is exposed to forces consisting essentially of a vertically upward flow force and a vertically downward force of gravity.

Claim 6

The process of claim 1, comprising establishing a recycle stream of at least a portion of said aqueous leachate, said recycle stream exiting said column at said upper clarifying zone and re-entering said column at said lower leaching zone.

Claim 7

The process claim 5, comprising flowing said recycle stream through a metal recovery bed upstream of the re-entry of said column to remove metal from the recycle stream prior to re-entry into said column.

Claim 8

A process for recovering a metal from a selected containing the metal, the metal being selected form the group consisting of gold, uranium, copper, zinc, nickel and lead; and wherein said material is selected form the group consisting of ores, concentrates and calcines, which process comprises continuously passing an aqueous solution of leaching agent, which is initially saturated with dissolved oxygen, countercurrent through a fluidized column of an aqueous slurry containing the material and recovering at least a portion of leachate containing the metal, while introducing said aqueous solution of leaching agent into the column at a velocity effective to maintain a bed of said column in a fluidized state.

Claim 9

A process for recovering a metal from a selected containing the metal, the metal being selected form the group consisting of gold, uranium, copper, zinc, nickel and lead; and wherein said material is selected form the group consisting of ores, concentrates and calcines, which process comprises continuously passing an aqueous solution of leaching agent, which is initially saturated with dissolved oxygen, countercurrent through a fluidized column of an aqueous slurry containing the material and recovering at least a portion of leachate containing the metal, while introducing said aqueous solution of leaching agent into the column at a velocity effective to maintain a bed of said column in a fluidized state.

Claim 10

The process of claim 7, in which the column increases in cross-section from a lower solution-introduction zone to an upper leachate recovery zone.

Claim 11

The process of claim 7, which is a batch process.

Claim 12

The process of claim 7, which further comprises drawing off leachate from an upper portion of the column and adding the same to additional aqueous solution containing leaching agent, which is initially saturated with dissolved oxygen, and introducing the aqueous solution containing leachate as a recycle stream into a lower part of the column.

Claim 13

The process as defined in claim 7, which comprises, in a plurality of fluidized columns in series, including an initial column and a final column and one or more intermediate fluidized columns: a) adding fresh material to the initial column, and passing the same as partly leached material to said one or more intermediate columns and then to said final column, where leached material is recovered; b) adding fresh aqueous solution of leaching agent to a lower part of the final column in a solution which is initially saturated with dissolved oxygen; c) passing leachate containing leaching agent from a top zone in the final column into a lower part of an intermediate zone; d) passing leachate containing leaching agent from a top zone in the intermediate column into a lower part of the initial column, and combining the same with aqueous solution which is initially saturated with oxygen; and e) recovering leachate from an upper zone of an initial column.

Claim 14

The process of claim 1, wherein a portion of the leachate and the top zone of each of said initial, intermediate and final columns is returned to the lower part of the same column as part of the solution containing dissolved oxygen.

Claim 15

The process of claim 11, which comprises: a) combining the portion of the leachate from the top zone of said final column with said fresh leaching chemical to form a combined final stream, dissolving oxygen in said combined final stream and passing said combined final stream containing dissolved oxygen into said lower part of said final column, b) combining the portion of leachate from the top zone of said intermediate column with said leachate passed from said top zone of said final column to form a combined intermediate stream, dissolving oxygen in the combined intermediate stream and passing the combined intermediate stream containing dissolved oxygen into the lower part of the intermediate column, and c) combining the portion of leachate from the top zone of said initial column with said leachate passed from said top zone of said intermediate column to form a combined initial stream, dissolving oxygen in the combined initial stream and passing the combined initial stream containing dissolved oxygen into the lower part of the initial column.

Claim 16

A process for recovering a metal from a material containing the metal, said metal being selected from the group consisting of gold, uranium, copper, zinc, nickel and lead; and said material being selected form the group consisting of ores, concentrates and calcines, the process comprising: a) providing, in a vertically elongated vessel having a wall tapering outward from a floor to an open mouth at the top, a fluid column made up of an aqueous dispersion of the material; b) continuously feeding into the column an aqueous slurry of the material as in inflow; c) forming a recycle stream by drawing from an upper part of the column an overflow, adding leaching chemical to the recycle stream, dissolving oxygen in the recycle stream and recycling it to a lower part of the column; d) maintaining the column at a leaching extraction temperature and the concentration of leaching chemical at a leaching extraction level; e) controlling the flow of the recycle stream into the fluid column, at a velocity to maintain the bed fluidized and to maintain at upward flow of liquid in contact with the solids of the slurry, whereby a substantially clear liquor is separated from the solids to provide the overflow; f) withdrawing, from an intermediate height in the column, a slurry of the material which has been treated into the column as an outflow; g) coordinating the inflow and outflow of slurry with the inflow of the recycle stream to maintain the column at a depth in the vessel; and h) causing an overflow of low suspended leached solids liquid from the top of the column containing leaching chemicals.

Claim 17

A process for recovering a metal from a material containing the metal, said metal being selected from the group consisting of gold, uranium, copper, zinc, nickel and lead; and said material being selected form the group consisting of ores, concentrates and calcines, the process comprising: a) providing, in a vertically elongated vessel having a wall tapering outward from a floor to an open mouth at the top, a fluid column made up of an aqueous dispersion of the material; b) continuously feeding into the column an aqueous slurry of the material as in inflow; c) forming a recycle stream by drawing from an upper part of the column an overflow, adding leaching chemical to the recycle stream, dissolving oxygen in the recycle stream and recycling it to a lower part of the column; d) maintaining the column at a leaching extraction temperature and the concentration of leaching chemical at a leaching extraction level; e) controlling the flow of the recycle stream into the fluid column, at a velocity to maintain the bed fluidized and to maintain at upward flow of liquid in contact with the solids of the slurry, whereby a substantially clear liquor is separated from the solids to provide the overflow; f) withdrawing, from an intermediate height in the column, a slurry of the material which has been treated into the column as an outflow; g) coordinating the inflow and outflow of slurry with the inflow of the recycle stream to maintain the column at a depth in the vessel; and h) causing an overflow of low suspended leached solids liquid from the top of the column containing leaching chemicals.

Claim 18

The process of claim 14, wherein a plurality of said vertically elongated vessels are employed in series, each being provided with a fluid column, the vessels comprising a first vessel, at least one intermediate vessel, and a terminal vessel, the process comprising: a) feeding raw material to the first column, b) withdrawing leached slurry from the terminal column, c) passing partially leached slurry from the first column serially to the subsequent columns, d) providing fresh leaching chemical to the recycle stream of the terminal column, e) providing the recycle stream of the intermediate sand first columns with a supply of leaching chemical in low solids liquid overflowing from the succeeding column, and f) discharging the leaching chemical in the low solids overflow from the first column.

Claim 19

The process of claim 14, wherein the material is ore containing uranium.

Claim 20

The process of claim 16, wherein the leaching chemical comprises sulphuric acid.

Claim 21

A process for leaching a metal from a material containing the metal, the metal being selected from the group consisting of gold, uranium, copper, zinc, nickel and lead, and said material being selected from the group consisting of ores, concentrates and calcines; which comprise passing a leaching agent being saturated with dissolved oxygen upwardly through a bed of the material at a velocity sufficient to maintain a fluidized bed and recovering leachate containing the metal from said bed.

Claim 22

A process for leaching a metal from a material containing the metal, the metal being selected from the group consisting of gold, uranium, copper, zinc, nickel and lead, and said material being selected from the group consisting of ores, concentrates and calcines; which comprise passing a leaching agent being saturated with dissolved oxygen upwardly through a bed of the material at a velocity sufficient to maintain a fluidized bed and recovering leachate containing the metal from said bed.

Claim 23

A process for countercurrent contacting of fluids and solids wherein interaction occurs while the solids are dispersed at least in part in the fluid, comprising: a) passing a flow of a solution containing leaching agent and being saturated with dissolved oxygen outwardly through a bed of a material selected from the group consisting of ores, concentrates and calcines, which contains a leachable water-soluble metal selected from the group consisting of gold, uranium, copper, zinc, nickel and lead, in volume and a velocity effective to provide a fluid bed surmounted by a supernatant body of a relatively clarified solution containing said water soluble component; b) recycling a part of the relatively clarified solution by drawing it from said supernatant body, dissolving oxygen in it and passing it into the bottom of said bed; c) separating steps a) and b) until the material bed is substantially spent; and d) recovering metal from the solution.

Claim 24

A process for countercurrent contacting of fluids and solids wherein interaction occurs while the solids are dispersed at least in part in the fluid, comprising: a) passing a flow of a solution containing leaching agent and being saturated with dissolved oxygen outwardly through a bed of a material selected from the group consisting of ores, concentrates and calcines, which contains a leachable water-soluble metal selected from the group consisting of gold, uranium, copper, zinc, nickel and lead, in volume and a velocity effective to provide a fluid bed surmounted by a supernatant body of a relatively clarified solution containing said water soluble component; b) recycling a part of the relatively clarified solution by drawing it from said supernatant body, dissolving oxygen in it and passing it into the bottom of said bed; c) separating steps a) and b) until the material bed is substantially spent; and d) recovering metal from the solution.