FI60702B - BLANDNING AV 5-NONYL-2-HYDROXIBENSALDOXIMER ANVAENDBAR FOER EXTRAKTION AV KOPPAR - Google Patents

Description

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Patent- oeh registerstyrelsen 'Antttktn utlagd och uti.ikriftcn publtearad 30.11. oi (32) (33) (31) Privilege claimed — Begird prlorltet 21.03.72

England-England (GB) 13158/72 Proven

Styrkt (71) Imperial Chemical Industries Limited, Imperial Chemical House, Millbank,

London S.W.1, England-England (GB) (72) Norman Ackerley, Blackley, Manchester, Peter Albert Mack, Blackley,

This invention relates to a process for the extraction of copper. The present invention relates to a process for the extraction of copper to the Kolster Ab (5U) mixture of 5-nonyl-2-hydroxybenzaldoximes for copper extraction. aqueous solutions, and in particular those obtained by extracting copper from its ores.

One method of extracting metals from ores is to crush and extract the ore with acids, for example, to obtain an aqueous solution of a salt of the desired metal, usually in combination with other metal salts present in the ore. The aqueous solution can then be treated with a complexing group, i.e., a ligand, with which the desired metal forms a complex compound under treatment conditions that is soluble in a water-immiscible organic solvent. It is convenient to use a solution of the ligand in a solvent and to carry out the treatment and extraction at the same time. It has now been found that certain salicylaldoximes are very valuable ligands suitable for this method of assistance.

The invention relates to a copper extraction agent consisting of an isomeric mixture of 5-nonyl-2-hydroxybenzaldoximes prepared from nonylphenol, the composition of the 5-nonyl groups corresponding to a mixture of branched isomers of the same type as those present in the nylon group. prepared by alkylation of phenol with a propylene trimer.

From J. South African Chem. Inst. Butter. 23 (1970), pp. 129-135, it is known that long chain derivatives of salicylaldoximes can be used as liquid ion exchangers for the selective extraction of copper in the low pH range; is mentioned e.g. 5-octyl-2-hydroxybenzaldoxime and 5-dodecyl-2-hydroxybenzaldoxime. The 5-nonyl-2-hydroxybenzoxydimes of the invention and their copper complexes are significantly more soluble in conventional low aromatic solvents than the known 5-octyl derivative, the use of which in conventional solvents is not considered commercially viable. Although the known 5-octyl derivative is reasonably soluble in aromatic-rich solvents (which, however, are not desired), the migration of copper in such solutions is relatively small in both extraction and stripping. The known 5-dodecyl derivative and its copper complex are soluble in conventional low aromatic solvents, but when the 5-nonyl derivative is used according to the invention, the rate of copper extraction and stripping and the separation of copper from the organic phase and the aqueous phase are considerably higher than when using 5_dec.

Salicylaldoximes can be prepared by conventional means, for example by reaction of hydroxylamine (such as as the hydrochloride in the presence of sodium acetate) with the corresponding salicylaldehydes, which in turn are prepared by conventional methods, for example by placing the formal group in the ortho position in a suitable substituted phenol.

The mixture according to the invention is applied to the extraction of copper.

The conditions, in particular the pH, under which the extraction is used are selected to be suitable for the metal or metals present in the aqueous solution. In general, it is desirable that, under the selected conditions, the other metals present do not form stable complexes with salicylaldoxime so that substantially only the desired metal, i.e. copper, is extracted from the aqueous solution. Since the formation of a complex compound may involve the release of an acid, it may be necessary to add, for example, alkali during the process to maintain the pH in the desired range where the metal complex is stable. These salicylaldoximes are very suitable for copper extraction because this metal forms a complex that is stable at low pH values and when operating at pH values below 3, 3,70702 copper can be extracted substantially completely free of iron, cobalt and nickel.

As the organic solvent, any non-viscous organic solvent or solvent mixture which is immiscible with water and inert to water and ligands under the pH conditions used can be used, such as, for example, aliphatic and aromatic hydrocarbons, esters, ethers and halogenated hydrocarbons.

To facilitate the separation of the aqueous phase and the solvent phase, it is desirable to use a solvent whose density is clearly different from that of the aqueous layer when the solvent contains salicylaldoxime and a complex compound.

If the solvents contain suspended complex compounds which may tend to settle to the bottom of the solvent layer, it is very advantageous to use solvents with a density higher than aqueous solutions, as these are more easily separable from the aqueous layer than solvents with a density lower than water and suspended metal complexes may concentrate. -water interface. Examples of solvents having such a density are halogenated hydrocarbons such as perchlorethylene, trichloroethane, trichlorethylene and chloroform.

The extraction can be suitably used by combining an aqueous solution and a solution of salicylaldoxime in an organic solvent at a suitable temperature, preferably ambient temperature, by stirring or otherwise disturbing the liquid mixture so that the water-solvent intermediate layer has a large surface area to promote complex formation and extraction, and then reducing the mixing so that the aqueous and solvent layers settle in place and can be conveniently separated. The extraction can be carried out batchwise or, preferably, continuously, and in either case the solvent can be released from the copper before it is reused.

The amount of organic solvent used can be selected according to the volume of the aqueous solution to be extracted, the concentration of the metals and the equipment used to carry out the process. In general, it is not necessary to use an amount of solvent sufficient to ensure complete dissolution of the complex formed, because the excess fraction of the complex usually remains as a suspension in an organic solvent and does not interfere with solvent handling and separation, especially if it has a higher density than water. It is advantageous, especially when using a continuous process, to bring together approximately equal volumes of organic solution and aqueous solution.

1 * 60702

If desired, mixtures of saicylidene oximes and other ligands may be used and other compounds such as conditioning agents may be present, for example long chain aliphatic alcohols such as caprylic alcohol, isode-cananol, tridecyl alcohol or 2-ethylhexanol to facilitate or modify the formation of the complex. 5-10 weight /? the amount of organic solvent.

It may sometimes be desirable to add surfactants such as ethylene oxide / alkylphenol condensates to facilitate separation of the aqueous phase and the organic phase by reducing the tendency to emulsify.

It is preferred to use solvent solutions containing 2-50% salicyl aldoxime.

Copper can be separated from the solvent after the extraction step by any conventional process, for example, by extraction into the aqueous phase under pH conditions in which the complex is unstable, or by hydrogenation. Such a treatment regenerates salicylaldoxime, and the salicylaldoxime-containing solvent thus recovered can be suitably reused in the process, especially when working continuously.

The mixture according to the invention can be used in particular for the extraction of aqueous solutions obtained from the treatment of ore minerals, scrap metal or other metallic wastes with aqueous acid solutions such as sulfuric acid, sulfuric acid, hydrochloric acid or nitric acid or from aqueous solutions of ammonia or ammonium carbonate. .

Extraction is generally very suitable for the recovery of copper from solutions containing at least 5 g of copper per liter. However, salicylaldoximes containing alkyl groups ortho to the hydroxy group are most suitable for use with weaker solutions.

The invention is illustrated by the following examples. All parts and percentages are by weight unless otherwise indicated.

Example 1 20 volumes of an aqueous solution of copper sulphate having a pH of 2 and containing U5 g of copper per liter were shaken with 60 volumes of a solution containing 7.1 * parts by weight of 5-nonyl-2-hydroxybenzaldoxime in a hydrocarbon solvent bearing the trade name Shellsol T, 3 minutes at ambient temperature. The aqueous phase was separated from the hydrocarbon solution and found to contain 10.82 g of copper per liter.

This aqueous step was then extracted a second time with a fresh solution of 5-nonyl-2-hydroxybenzaldoxime. The aqueous solution obtained from the second extraction was found to contain 1.23 g of copper per liter. The third extraction reduced the copper content of the aqueous solution to 0.086 g / liter.

The 5-nonyl-2-hydroxybenzaldehyde used in this example was prepared as follows:

A mixture of 270 parts of 1i-nitroso-N, N-dimethylaniline, ÖOO part of a UO% aqueous solution of formaldehyde, 1700 parts of methyl alcohol and UHO part of a commercial grade 4-nonylphenol (manufactured by ICI Ltd.) in which the nonyl group is a branched chain isomer prepared by alkylation of phenol with portions of propylene nitride) was stirred while a strong stream of hydrochloric acid gas was introduced. The temperature of the mixture rose rapidly between 55 ~ and 60 ° C. The mixture was kept at reflux at this temperature for 1-2 hours, after which the exothermic reaction subsided. The flow of hydrochloric acid gas was stopped and the condensed steam in the reaction mixture was changed from the reflux station to the distillation station. After collecting about 700 parts of distillate, 500 parts of water were added to the distillation residue and the mixture was allowed to separate.

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The aqueous phase was removed and the residual oil was distilled in vacuo. In the range 135-1 ^ 50, a 0.6 mm distilled fraction was collected and refluxed with a UOU portion of hydroxylamine hydrochloride, 570 parts of potassium acetate and 1090 parts of ethyl alcohol for 2 hours. The mixture was then filtered and the inorganic cake was washed with 500 parts of ethyl alcohol. The filtrates were evaporated to remove alcohol and the remaining syrup was dissolved in 500 parts of chloroform. This solution was washed by shaking with water and then the chloroform was removed on a rotary evaporator. As a residue, 350 parts of 5-nonyl-2-hydroxybenzaldehyde were obtained as a viscous straw-colored liquid with clear peaks in the infrared spectrum at 3.00 and 1625 cm-1.

Example 2 60 volumes of a solution containing 5 parts by weight of 5-nonyl-2-hydroxy-benzaldoxime in a hydrocarbon solvent under the trade name Shellsol T were stirred vigorously at ambient temperature for 5 minutes with 20 volumes of a feed water solution containing divalent metal sulfates and having a pH of the initial value was 2. The steps were separated and the hydrocarbon solution was successively contacted with two additional batches of fresh aqueous feed solution. The initial feed water solution contained 1 * 5000 ppn of copper, 2000 ppm of iron, 2000 ppm of cobalt and 200 ppm of zinc. After three extractions, the hydrocarbon solvent was found to contain 1,000,000 copper, 5 ppm iron, 1 ppm cobalt less than 1 ppm zinc.

Example 3 100 parts by volume of a solution containing 12.3 parts by weight of 5-nonyl-2-hydroxybenzaldoxime prepared as described in Example 1 in a hydrocarbon solvent under the trade name Shellsol T was shaken with successive portions of an aqueous solution of copper sulphate until 1.38 parts by weight of copper had been extracted into the hydrocarbon solvent. Copper was removed from the charged hydrocarbon solution at ambient temperature by two successive 5-minute extractions using 6,60702 stripping solutions consisting of 100 volumes of a solution containing 30 g of copper and 200 g of sulfuric acid per liter. In this way, 0.75 part by weight of copper was removed from the hydrocarbon solvent to the removal solutions, its net transition efficiency was 50 * 5% ·