Chemistry of inorganic compounds – Treating mixture to obtain metal containing compound – Group ib metal
Reexamination Certificate
2001-06-11
2004-04-27
Bos, Steven (Department: 1754)
Chemistry of inorganic compounds
Treating mixture to obtain metal containing compound
Group ib metal
C423S099000, C423S139000, C252S184000
Reexamination Certificate
active
06726887
ABSTRACT:
The present invention concerns a solvent extraction composition, a solvent extraction process and especially a process for the extraction of metals, particularly copper, from aqueous solutions, especially solutions obtained by leaching ores.
It is known to extract metals, especially copper, from aqueous solutions containing the metal in the form of, for example, a salt, by contacting the aqueous solution with a solution of a solvent extractant in a water immiscible organic solvent and then separating the solvent phase loaded with metal, i.e. containing at least a part of the metal in the form of a complex. The metal can then be recovered by stripping with a solution of lower pH followed for example, by electrowinning. Most commonly, the aqueous metal-containing solutions for extraction are the result of the acid leaching of ores. However it is known that some metals, especially copper, can be leached from certain ores with ammoniacal solutions. This has the advantage that solutions containing especially high concentrations of copper are derived and that there is little contamination of the solution with iron.
Solvent extractants which have found favour in recent years particularly for the recovery of copper from aqueous solutions include oxime reagents, especially o-hydroxyaryloximes and o-hydroxyarylketoximes. Whilst such reagents have been found to work well in the recovery of copper from solutions, one problem which has been encountered in the application of such reagents is that the oxime and ketoxime reagents can strongly bind metals to the extent that the efficiency of metal transfer from leach solution to strip solution can be impaired. In order to overcome such problems, modifiers have been used to effect the binding efficiency of the extractants. Typical modifiers are disclosed in WO96/25525, and in particular a class of highly branched ester modifiers are disclosed in EP-A-0202833. However, as solvent extraction processes are increasingly employed in more diverse situations, there is still a need to identify further modifiers.
According to a first aspect of the present invention, there is provided a solvent extraction composition comprising one or more orthohydroxyarylaldoximes or orthohydroxyarylketoximes, and one or more esters substituted with a hydroxy group.
The compositions preferably also comprise a water immiscible organic solvent.
The orthohydroxyarylaldoxime or orthohydroxyarylketoxime compounds employed in the present invention are substantially water insoluble and preferably have the formula:
wherein
R
1
is hydrogen or an optionally substituted hydrocarbyl group
R
2
is an optionally substituted ortho-hydroxyaryl group, and salts thereof.
Whilst the invention is described herein with reference to a compound of Formula (1), it is understood that it relates to said compound in any possible tautomeric forms, and also the complexes formed between orthohydroxyarylaldoximes or orthohydroxyarylketoximes and metals, particularly copper.
Optionally substituted hydrocarbyl groups which may be represented by R
1
preferably comprise optionally substituted alkyl and aryl groups including combinations of these, such as optionally substituted aralkyl and alkaryl groups.
Examples of optionally substituted alkyl groups which may be represented by R
1
include groups in which the alkyl moieties can contain from 1 to 20, especially from 1 to 4, carbon atoms. A preferred orthohydroxyarylketoxime is one in which R
1
is alkyl, preferably containing up to 20, and especially up to 10, and more preferably up to 3 saturated aliphatic carbon atoms, and most preferably R
1
is a methyl group.
Examples of optionally substituted aryl groups which may be represented by R
1
include optionally substituted phenyl groups. When R
1
is an aryl group, it is preferably an unsubstituted phenyl group.
Most preferably R
1
represents a hydrogen atom.
Optionally substituted ortho-hydroxyaryl groups which may be represented by R
2
include optionally substituted phenols. Examples of optionally substituted phenols which may be represented by R
2
include those of formula:
wherein R
3
to R
6
each independently represent H or a C
1
to C
22
, preferably a C
7
to C
15
, linear or branched alkyl group. Particularly preferably only R
5
represents a C
1-22
alkyl group, most preferably a C
7
to C
15
alkyl group, with R
3
, R
4
and R
6
representing H.
When R
1
or R
2
is substituted, the substituent(s) should be such as not to affect adversely the ability of the orthohydroxyarylaldoxime or orthohydroxyarylketoxime to complex with metals, especially copper. Suitable substituents include halogen, nitro, cyano, hydrocarbyl, such as C
1-20
-alkyl, especially C
1-10
-alkyl; hydrocarbyloxy, such as C
1-20
-alkoxy, especially C
1-10
-alkoxy; hydrocarbyloxycarbonyl, such as C
1-20
-alkoxycarbonyl, especially C
1-10
-alkoxycarbonyl; acyl, such as C
1-20
-alkylcarbonyl and arylcarbonyl, especially C
1-10
-alkylcarbonyl and phenylcarbonyl; and acyloxy, such as C
1-20
-alkylcarbonyloxy and arylcarbonyloxy, especially C
1-10
-alkylcarbonyloxy and phenylcarbonyloxy. There may be more than one substituent in which case the substituents may be the same or different.
In many embodiments, when an orthohydroxyarylketoxime employed, the orthohydroxyarylketoxime is a 5-(C
8
to C
14
alkyl)-2-hydroxyacetophenone oxime, particularly 5-nonyl-2-hydroxyacetophenone oxime.
In many preferred embodiments, when an orthohydroxyarylaldoxime employed, the orthohydroxyarylaldoxime is a 5-(C
8
to C
14
alkyl)-2-hydroxybenzaldoxime, particularly 5-nonyl-2-hydroxybenzaldoxime.
The composition may comprise one or more different orthohydroxyarylaldoximes or orthohydroxyarylketoximes or mixtures thereof in which the nature of the substituent groups represented by R
1
and R
2
differ between component orthohydroxyarylaldoximes or orthohydroxyarylketoximes, especially where the component orthohydroxyarylaldoximes or orthohydroxyarylketoximes are isomeric. Such isomeric mixtures may have better solubility in organic solvents than a single orthohydroxyarylketoxime.
The orthohydroxyarylaldoximes or orthohydroxyarylketoximes are often present in an amount of up to 60% by weight of the composition, commonly no more than 50%, and usually no more than 40% w/w. Often, the orthohydroxyarylaldoxime or orthohydroxyarylketoxime comprises at least 1% by weight, commonly at least 2.5% by weight and usually at least 5% by weight of composition, and preferably comprises from 7.5 to 20%, such as about 10%, by weight of the composition.
The esters substituted with a hydroxy group employed in the present invention are substantially water insoluble and commonly have the formula:
wherein one of R
7
or R
8
is a substituted hydrocarbyl group which is substituted with at least one hydroxyl group and the other is an optionally substituted hydrocarbyl group. Preferably, the ester is an aliphatic or aromatic-aliphatic ester, and particularly preferably a branched chain aliphatic or aromatic-aliphatic ester.
The esters substituted with a hydroxy group (hereinafter Hydroxy-esters) which may be employed in this invention may be di-esters or polyesters, but are especially mono-esters.
The Hydroxy-esters of the present invention can contain from 5 to 51 carbon atoms, preferably from 7 to 40 carbon atoms, and more preferably from 9 to 25 carbon atoms.
The Hydroxy-esters are preferably highly branched. In the context of the present invention, “highly branched” means that the ratio of the number of methyl carbon atoms (CH
3
groups) to non-methyl carbon atoms (non CH
3
groups) is higher than 1:5 and preferably higher than 1:3, and is often less than 1.8:1, preferably less than 1.5:1.
Optionally substituted hydrocarbyl groups which may be represented by R
7
and R
8
preferably comprise optionally substituted alkyl and aryl groups including combinations of these, such as optionally substituted aralkyl and alkaryl groups.
Examples of optionally substituted alkyl groups which may be represented by R
7
and R
8
include groups in which the alkyl moieties can con
Bos Steven
Cytec Technology Corp.
Pillsbury & Winthrop LLP
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