Chemistry of inorganic compounds – Treating mixture to obtain metal containing compound – Group ib metal
Reexamination Certificate
2001-06-25
2003-10-14
Bos, Steven (Department: 1754)
Chemistry of inorganic compounds
Treating mixture to obtain metal containing compound
Group ib metal
C210S634000
Reexamination Certificate
active
06632410
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
BACKGROUND OF THE INVENTION
The present invention relates generally to solvent extraction processes for recovery of metal values from aqueous solutions and, more particularly, to a method of separating copper from iron resulting in a large improvement in the recovery of copper over iron.
Copper is generally obtained from its ore by a solvent extraction process wherein copper is in an aqueous leach solution obtained from a body of ore which contains a mixture of metals in addition to copper. The leaching medium dissolves salts of copper and other metals as it trickles through the ore, to provide an aqueous solution of the mixture of metal values. The metal values are usually leached with sulfuric acid medium, providing an acidic aqueous solution. The aqueous solution is mixed in tanks with an extraction reagent which is dissolved in an organic solvent, e.g., a kerosene. The reagent includes an extractant chemical which forms a metal-extractant complex with the copper ions in preference to ions of other metals. The step of forming the complex is called the extraction or loading stage of the solvent extraction process. The outlet of the mixing tanks is continuously fed to a large settling tank, where the organic solvent or organic phase, now containing the copper-extractant complex in solution, is separated from the depleted aqueous solution or aqueous phase. This part of the process is called phase separation. Usually, the process of extraction is repeated through two or more mixer-settler stages, in order to more completely extract the copper.
Among the more problematic copper bearing feedstocks treated in conventional solvent extraction processes are those in which quantities of dissolved iron values range from about 1 gpl or 20 gpl. Frequently the extractant chemical employed will form an iron-extractant complex which, in turn, results in the presence of iron in the strip aqueous phase. Where electrowinning is employed to recover copper from the strip aqueous solution, the presence of iron will complicate recovery by decreasing current efficiency. To avoid such problems, a more or less constant “bleed” of the tankhouse solution is established, with the solution bled off being circulated back into the initial feedstock or to the leach pile itself. Because such tankhouse bleed solutions contain appreciable amounts of copper and acid, efficiency of the entire system can be compromised.
The currently more favored reagents employed in recovery of copper values from aqueous solutions having iron values present are those which exhibit a relatively high degree of copper/iron selectivity, i.e., those which, under standard operating conditions, extract a high proportion of the copper present in the feedstock but only a minor proportion of the iron present. Among the reagents credited with displaying good copper/iron selectivity characteristics are those including hydroxy aryl oxime extractants such as long chain alkyl or alkenyl solubilized hydroxy aryl aldoximes and ketone oximes. See, for example, Birch, “The Evaluation of the New Copper Extractant ‘P-1’” appearing in the Proceedings of the 1974 International Solvent Extraction Conference, pp. 2837-2871, wherein “high selectivity against Fe (III) . . . in the sulphate system” is attributed to a reagent containing a 2-hydroxy-5-nonyl benzaldoxime extractant. Ketoximes such as 2-hydroxy-5-alkylphenyl ketoximes have also been used to selectively remove copper as described in U.S. Pat. No. 5,670,035, the entire contents of which are incorporated herein by reference. Each of the above-noted hydroxy aryl oxime-containing reagents has proven to extract undesirable amounts of iron from copper and iron-bearing ores. As a result, recovery of copper from such solutions necessitates at least some bleeding off of tankhouse solutions with losses to the overall economy of the system. Thus, there is a need to selectively remove copper to the more complete exclusion of iron from aqueous solutions containing copper and iron.
SUMMARY OF THE INVENTION
One aspect of the present invention pertains to a process for the separation of copper from iron in an aqueous feedstock solution containing dissolved copper and iron values comprising contacting the feedstock solution with a water-immiscible organic solution comprised of a hydrocarbon solvent and a compound of the formula I
wherein R
5
is a C
1-22
linear or branched alkyl group, a C
2-22
linear or branched alkenyl group, a C
6
aryl group, a C
7-22
aralkyl group, a halogen, OH or —OR
6
wherein R
6
is a C
1-22
linear or branched alkyl group, a C
2-22
linear or branched alkenyl group, a C
6
aryl group, a C
7-22
aralkyl group; R
1
is hydrogen, or a C
1-22
linear or branched alkyl or alkenyl group, a C
6
aryl group or a C
7-22
aralkyl group; R
2
-R
4
is hydrogen, halogen, a linear or branched C
6-12
alkyl group, —OR
6
wherein R
6
is a C
1-22
linear or branched alkyl group, a C
2-22
linear or branched alkenyl group, a C
6
aryl group, or a C
7-22
aralkyl group to form an aqueous phase comprised of iron and an organic phase comprised of the hydrocarbon solvent and a copper-extractant complex wherein the copper-extractant complex is soluble in the hydrocarbon solvent. The R
2
-R
5
groups are chosen so that the copper-extractant complex is soluble in the hydrocarbon solvent. After the extraction stage is completed and the organic and aqueous phases separate, the organic phase is substantially free of iron and/or an iron-extractant complex.
Another aspect of the invention pertains to novel ketoximes which are useful as extractants for copper and which are compounds of the formula II
wherein R
11
is a C
1-22
linear or branched alkyl group, a C
2-22
linear or branched alkenyl group, a C
6
aryl group, a C
7-22
aralkyl group, a halogen, OH or —OR
6
wherein R
6
is a C
1-22
linear or branched alkyl group, a C
2-22
linear or branched alkenyl group, a C
6
aryl group, a C
7-22
aralkyl group; R
7
is a C
1-22
linear or branched alkyl or alkenyl group, a C
6
aryl group or a C
7-22
aralkyl group; branched alkyl group, a C
2-22
linear or branched alkenyl group, a C
6
aryl group, a C
7-22
aralkyl group, a halogen, OH or —OR
12
wherein R
12
is a C
1-22
linear or branched alkyl group, a C
2-22
linear or branched alkenyl group, a C
6
aryl group, a C
7-22
aralkyl group; R
7
is a C
1-22
linear or branched alkyl group, a C
2-22
linear or branched alkenyl group, a C
6
aryl group or a C
7-22
aralkyl group; R
8
-R
10
is hydrogen, halogen, a linear or branched C
6-12
alkyl group, —OR
12
wherein R
12
is a C
1-22
linear or branched alkyl group, a C
2-22
linear or branched alkenyl group, a C
6
aryl group, or a C
7-22
aralkyl group with the proviso that the total number of carbon atoms in R
8
-R
10
is at least 7.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
Not Applicable.
DETAILED DESCRIPTION
In the process for the separation of copper from iron in an aqueous feedstock solution containing dissolved copper and iron values, the feedstock solution is contacted with a water-immiscible organic solution comprised of a hydrocarbon solvent and a compound of the formula I
wherein R
5
is a C
1-22
linear or branched alkyl group, a C
2-22
linear or branched alkenyl group, a C
6
aryl group, a C
7-22
aralkyl group, a halogen, OH or —OR
6
wherein R
6
is a C
1-22
linear or branched alkyl group, a C
2-22
linear or branched alkenyl group, a C
6
aryl group, a C
7-22
aralkyl group; R
1
is hydrogen, or a C
1-22
linear or branched alkyl or alkenyl group, a C
6
aryl group or a C
7-22
aralkyl group; R
2
-R
4
is hydrogen, halogen, a linear or branched C
6-12
alkyl group, —OR
6
wherein R
6
is a C
1-22
linear or branched alkyl group, a C
2-22
linear or branched alkenyl group, a C
6
aryl group, or a C
7-22
aralkyl group to form an aqueous phase comprised of iron and an organic phase comprised of the hydrocarbon solvent and a copper-extractant complex wherein the copper-extractant complex is solubl
Kang Sang I.
Mattison Phillip L.
Sudderth R. Brantley
Virnig Michael J.
Wolfe George A.
Bos Steven
Cognis Corporation
Drach John E.
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