Methods for selective leaching and extraction of precious metals in organic solvents

Patent metadata

Field	Value
Publication number	US-2018112289-A1
Application number	US-201615568230-A
Country	US
Kind code	A1
Filing date	Apr 21, 2016
Priority date	Apr 21, 2015
Publication date	Apr 26, 2018
Grant date	—

Abstract

The present application relates to methods for leaching and extraction of precious metals. For example, the present application relates to methods of leaching gold, palladium and/or platinum from a substance comprising gold, palladium and/or platinum (such as a gold-containing ore or a platinum group metal (PGM) concentrate) using an organic solvent that is water-miscible or partially water-miscible.

First claim

1 . A method of leaching gold, palladium and/or platinum from a substance comprising gold, palladium and/or platinum, the method comprising contacting the substance with a mixture comprising:
(a) an acid; (b) an oxidizing agent; and (c) a water-miscible or partially water-miscible organic solvent, under conditions to leach the gold, palladium and/or platinum from the substance.

2 . The method of claim 1 , wherein the method further comprises:
separating the water-miscible or partially water-miscible organic solvent containing the leached gold, palladium and/or platinum from insoluble impurities; and evaporating the water-miscible or partially water-miscible organic solvent from the leached gold, palladium and/or platinum.

3 . The method of claim 2 , wherein the method further comprises, after evaporating, treating the leached gold, palladium and/or platinum with a compound of Formula I:

wherein
R 1 is —NR 4 R 5 or aryl;
R 2 and R 3 are each independently selected from H, C 1-10 alkyl, C 3-10 cycloalkyl, C 1-6 alkyleneC 3-10 cycloalkyl, heterocycloalkyl and aryl; or
R 2 and R 3 together with the nitrogen atom to which they are attached, form a heterocycloalkyl or a heteroaryl, or a heterocycloalkyl or a heteroaryl substituted at one or more carbon atoms with C 1-4 alkyl;
R 4 and R 5 are each independently selected from H, C 1-10 alkyl, C 3-10 cycloalkyl, C 1-6 alkyleneC 3-10 cycloalkyl, heterocycloalkyl and aryl; or
R 4 and R 5 together with the nitrogen atom to which they are attached, form a heterocycloalkyl or a heteroaryl, or a heterocycloalkyl or a heteroaryl substituted at one or more carbon atoms with C 1-4 alkyl;
X is O or S;
Y is S, NR 6 or CR 6 R 7 ; and
R 6 and R 7 are each independently selected from H, C 1-10 alkyl, C 3-10 cycloalkyl, C 1-6 ealkyleneC 3-10 cycloalkyl, heterocycloalkyl and aryl,

under conditions to form a complex between the compound of Formula I and the leached gold and/or palladium.

4 . The method of claim 3 , wherein the compound of Formula I is a compound of Formula I (a):

wherein R 2 , R 3 , R 4 , R 5 and Y are as defined in claim 3 .

5 . (canceled)

6 . The method of claim 4 , wherein R 2 and R 3 together with the nitrogen atom to which they are attached form a heterocycloalkyl or a substituted heterocycloalkyl, wherein the heterocycloalkyl is selected from aziridinyl, azetidinyl, pyrrolidinyl, piperidinyl, azepanyl, azocanyl, imidazolidinyl, oxazolidinyl, thiazolidinyl, piperazinyl, hexahydropyrimidinyl, morpholinyl, 1,3-oxazinanyl, thiomorpholinyl, 1,3-thiazinanyl, 1,3-diazepanyl, 1,3-oxazepanyl, 1,3-thiazepanyl, 1,4-diazepanyl, 1,4-oxazepanyl, 1,4-thiazepanyl, 1,3-diazocanyl, 1,3-oxazocanyl, 1,3-thiazocanyl, 1,4-diazocanyl, 1,4-oxazocanyl, 1,4-thiazocanyl, 1,5-diazocanyl, 1,5-oxazocanyl and 1,5-thiazocanyl.

7 . (canceled)

8 . The method of claim 4 , wherein R 4 is H and R 5 is C 1-6 alkyl or C 3-8 cycloalkyl.

9 . The method of claim 3 , wherein Y is NR 6 .

10 . (canceled)

11 . The method of claim 3 , wherein the compound of Formula I is a compound of Formula I(a)(i), I(a)(ii), I(a)(iii) or I(a)(iv):

12 . (canceled)

13 . (canceled)

14 . The method of claim 3 , wherein the conditions to form the complex between the compound of Formula I and the leached gold and/or palladium comprise treating the leached gold, palladium and/or platinum with the compound of Formula I in a water-immiscible organic solvent for a time of about 2 minutes to about 30 minutes at a temperature of about 10° C. to about 40° C.

15 . (canceled)

16 . The method of claim 3 , wherein the method further comprises stripping the gold and/or palladium from the complex between the compound of Formula I and the leached gold and/or palladium by a method comprising treating the water-immiscible organic solvent containing the complex between the compound of Formula I and the leached gold and/or palladium with an aqueous solution comprising an acid and thiourea under conditions to obtain a gold and/or palladium-containing strip solution and a gold and/or palladium-reduced organic phase comprising the compound of Formula I.

17 . The method of claim 16 , wherein the method further comprises separating the gold and/or palladium-containing strip solution from the gold and/or palladium-reduced organic phase comprising the compound of Formula I and recovering gold and/or palladium from the gold and/or palladium-containing strip solution by electrowinning or reduction.

18 . The method of claim 1 , wherein the method further comprises:
separating the water-miscible or partially water-miscible organic solvent containing the leached gold, palladium and/or platinum from insoluble impurities; treating the leached gold, palladium and/or platinum in the water-miscible or partially water-miscible organic solvent with a reducing agent under conditions to obtain gold, palladium and/or platinum; and separating the gold, palladium and/or platinum from the water-miscible or partially water-miscible organic solvent.

19 . (canceled)

20 . (canceled)

21 . The method of claim 18 , wherein the method further comprises, after separating the gold, palladium and/or platinum from the water-miscible or partially water-miscible organic solvent:
dissolving the gold, palladium and/or platinum in aqua regia; and treating the dissolved gold, palladium and/or platinum with a compound of Formula I;

wherein
R 1 is —NR 4 R 5 or aryl,
R 2 and R 3 are each independently selected from H, C 1-10 alkyl, C 3-10 cycloalkyl, C 1-6 alkyleneC 3-10 cycloalkyl, heterocycloalkyl and aryl; or
R 2 and R 3 together with the nitrogen atom to which they are attached, form a heterocycloalkyl or a heteroaryl, or a heterocycloalkyl or a heteroaryl substituted at one or more carbon atoms with C 1-4 alkyl;
R 4 and R 5 are each independently selected from H, C 1-10 alkyl, C 3-10 cycloalkyl, C 1-6 alkyleneC 3-10 cycloakyl heterocycloalkyl and aryl; or
R 4 and R 5 together with the nitrogen atom to which they are attached, form a heterocycloalkyl or a heteroaryl, or a heterocycloalkyl or a heteroaryl substituted at one or more carbon atoms with C 1-4 alkyl;
X is O or S;
Y is S, NR 6 or CR 6 R 7 ; and
R 6 and R 7 are each independently selected from H, C 1-10 akyl, C 3-10 cycloalkyl, C 1-6 alkyleneC 3-10 cycloalkyl, heterocycloalkyl and aryl, under conditions to form a complex between the compound of Formula I and the dissolved gold and/or palladium.

22 . The method of claim 21 , wherein the conditions to form the complex between the compound of Formula I and the dissolved gold and/or palladium comprise treating the dissolved gold, palladium and/or platinum with the compound of Formula I in a water-immiscible organic solvent for a time of about 2 minutes to about 30 minutes at a temperature of about 10° C. to about 40° C.

23 . (canceled)

24 . The method of claim 21 , wherein the method further comprises stripping the gold and/or palladium from the complex between the compound of Formu

Assignees

• Univ Saskatchewan

Inventors

• Foley Stephen
• Salimi Hiwa
• Moradi Loghman

Classifications

• C07D211/16

  with acylated ring nitrogen atom · CPC title

• C25C7/06

  Operating or servicing · CPC title

• C25C1/20

  of noble metals · CPC title

• C22B1/00

  Preliminary treatment of ores or scrap · CPC title

• C07D295/215

  Radicals derived from nitrogen analogues of carbonic acid · CPC title