Process for beneficiating gold

Claim 2

A process for beneficiating particulate gold from foreign material with which it is mixed which comprises contacting the mixture with an iron carbonyl under conditions which cause the iron carbonyl to decompose and then cause a coating at the surface of the gold particles to the substantial exclusion of the foreign material so as to alter the surface characteristics of the gold particles thereby causing a selective enhancement of the magnetic susceptibility of the gold particles to the substantial exclusion of the foreign material so that a magnetic separation between the gold and foreign material may be effected.

Claim 3

The process of claim 1 in which the treated mixture is subjected to a magnetic field to remove gold particles from the foreign material.

Claim 4

The process of claim 1 in which the iron carbonyl is iron pentacarbonyl.

Claim 5

The process of claim 3 in which the carbonyl is in gaseous form and is contacted with the mixture in an inert carrier gas.

Claim 6

The process of claim 1 wherein the foreign material is selected from the group consisting of granite, quartz, muscovite, alumina, gypsum, albite, dolomite, calcite, hematite and silica.

Claim 7

The process of claim 1 wherein the mixture is magnetically cleaned and the non-magnetic fraction of the mixture is then contacted with iron carbonyl.

Claim 8

The process of claim 1 wherein the mixture of gold and foreign material is contacted with iron carbonyl at a temperature between 100° C. and 250° C.

Claim 9

A process for beneficiating gold mixed with foreign material, which comprises the steps of: (a) reducing the mixture to a particulate form; (b) placing the particulate mixture in a gas treatment chamber; (c) introducing iron carbonyl vapor into said chamber under conditions which preclude substantial non-selective decomposition of the iron carbonyl, and (d) maintaining the iron carbonyl vapor in contact with said mixture for a sufficient time for the iron carbonyl to selectively enhance the magnetic susceptibility of substantially all of the gold particles in the mixture.

Claim 10

A process for beneficiating gold mixed with foreign material, which comprises the steps of: (a) reducing the mixture to a particulate form; (b) placing the particulate mixture in a gas treatment chamber; (c) introducing iron carbonyl vapor into said chamber under conditions which preclude substantial non-selective decomposition of the iron carbonyl, and (d) maintaining the iron carbonyl vapor in contact with said mixture for a sufficient time for the iron carbonyl to selectively enhance the magnetic susceptibility of substantially all of the gold particles in the mixture.

Claim 11

The process of claim 8 wherein the temperature of the chamber is not in excess of about 250° C.

Claim 12

The process of claim 8 wherein the iron carbonyl vapor is contacted with said mixture at a temperature between 110° C. and 130° C.

Claim 13

The process of claim 8 wherein from about 0.25 to about 8 kilograms of iron carbonyl per metric ton of mixture are introduced into said chamber.

Claim 14

The process of claim 8 wherein the iron carbonyl vapor is maintained in contact with said mixture for less than one-half hour.

Claim 15

The process of claim 8 wherein the iron carbonyl gas is first contacted with an inert carrier gas and then introduced into said chamber.

Claim 16

A process for recovering gold from a mixture of gold with other material which comprises contacting the mixture with a carbonyl of a Group VIII metal under conditions which cause the Group VIII metal carbonyl to decompose and then cause a coating at the surface of the gold to the substantial exclusion of the other material so as to alter the surface characteristics of the gold thereby causing a selective enhancement of the magnetic susceptibility of the gold to the substantial exclusion of the other material so that a magnetic separation between the gold and said other material may be effected.

Claim 17

A process for recovering gold from a mixture of gold with other material which comprises contacting the mixture with a carbonyl of a Group VIII metal under conditions which cause the Group VIII metal carbonyl to decompose and then cause a coating at the surface of the gold to the substantial exclusion of the other material so as to alter the surface characteristics of the gold thereby causing a selective enhancement of the magnetic susceptibility of the gold to the substantial exclusion of the other material so that a magnetic separation between the gold and said other material may be effected.

Claim 18

The process of claim 14 in which the Group VIII metal is a member selected from the group consisting of iron, nickel and cobalt.

Claim 19

The process of claim 15 in which the metal is iron.

Claim 20

A process for beneficiating gold mixed with foreign material, comprising: (a) reducing the mixture to a particulate form; (b) placing the particulate mixture in a gas treatment chamber; (c) contacting an inert carrier gas with iron carbonyl vapor to incorporate the iron carbonyl vapor in the carrier gas; (d) introducing the iron carbonyl vapor carried in the carrier gas into said chamber at a rate of from about 0.5 to about 4.0 kilograms of iron carbonyl per metric ton of particulate material and at a temperature from about 110° C. to about 130° C. (e) maintaining the iron carbonyl vapor in contact with said mixture for less than one-half hour to selectively enhance the susceptibility of substantially all of the gold particles in the mixture; (f) separating the gold particles from the mixture by magnetic separation.

Claim 21

A process for beneficiating gold mixed with foreign material, comprising: (a) reducing the mixture to a particulate form; (b) placing the particulate mixture in a gas treatment chamber; (c) contacting an inert carrier gas with iron carbonyl vapor to incorporate the iron carbonyl vapor in the carrier gas; (d) introducing the iron carbonyl vapor carried in the carrier gas into said chamber at a rate of from about 0.5 to about 4.0 kilograms of iron carbonyl per metric ton of particulate material and at a temperature from about 110° C. to about 130° C. (e) maintaining the iron carbonyl vapor in contact with said mixture for less than one-half hour to selectively enhance the susceptibility of substantially all of the gold particles in the mixture; (f) separating the gold particles from the mixture by magnetic separation.

Claim 22

The process of claim 17 wherein the iron carbonyl is iron pentacarbonyl.

Claim 23

The process of claim 8 wherein the iron carbonyl is iron pentacarbonyl.