DE1592264C3 - Process for the separation of cobalt and nickel from an aqueous solution containing cobalt and nickel - Google Patents

Description

ROP = O
OH

in which R denotes hydrogen, an alkyl, aryl or aralkyl group, with the proviso that, when both R are alkyl, aryl or aralkyl groups, each R contains at least 8 carbon atoms, and when one R is hydrogen the other R contains at least 12 carbon atoms in one inert organic solvent carried out, the resulting, metal-containing organic extract phase separated from the remaining aqueous phase and the organic extract phase to Metal removal is worked up, thereby characterized in that from the aqueous solution at a pH of 5.0 to 6.5 the Cobalt with an alkali or ammonium salt of organophosphoric acid of the general formula extracted.

2. The method according to claim 1, characterized in that there is used as the organophosphoric acid compound Ammonium (di- [2-ethylhexyl] phosphate) is used.

3. The method according to claim 1 or 2, characterized in that the organophosphoric acid compound used together with an emulsion inhibitor.

4. The method according to claim 3, characterized in that the emulsion inhibitor used is tributyl phosphate or isodecanol is used.

5. The method according to any one of claims 1 to 4, characterized in that from the with Cobalt-laden organic extract phase after separation from the remaining nickel-containing washes out aqueous phase with transferred nickel and then the cobalt with a 0.5 to 5 normal mineral acid separates.

6. The method according to claim 5, characterized in that one for washing out the nickel of the extract phase 0.6 η sulfuric acid, 0.6 η nitric acid or one per liter of 10 to 100 g of cobalt in Form of the sulfate or nitrate-containing solution is used.

7. The method according to any one of claims 1 to 6, characterized in that the extraction at at a temperature of 20 to 70 ° C.

tion with a solution of an organophosphoric acid compound of the general formula

R.
O

R-O-P = O

OH

The invention relates to a method for separating cobalt and nickel from a cobalt and nickel nickel-containing aqueous solution in which an Extrakin of R is hydrogen, an alkyl, aryl or Aralkyl group means, with the proviso that when both R's are alkyl, aryl, or aralkyl groups, then each R contains at least 8 carbon atoms and when one R is hydrogen the other R contains at least 12 carbon atoms contains, carried out in an inert organic solvent, the resulting, metal-containing organic extract phase separated from the remaining aqueous phase and the organic Extract phase is worked up to remove metal.

Aqueous acidic solutions containing cobalt and nickel are particularly present in large quantities Processes in which ores containing cobalt and nickel are reduced in a furnace and the calcined ores leached with an acid to dissolve the nickel and cobalt. There's a lot of interest the art of improved methods of separating nickel and cobalt from such solutions.

It is known (Industrial and Engineering Chemistry 1957, Vol. 49, p. 1056) that cobalt and nickel from cobalt and / or nickel-containing aqueous solutions by extraction using certain organic Phosphates can be separated and thereby concentrated. Information about a useful way of working to separate the cobalt from the nickel by extraction, if they are combined in one aqueous solution are present, but are not found. Leave the distribution coefficients listed there also see no possibility of separating these two metals on an industrial scale. For the only alkyl phosphate for which there are the distribution coefficients for both nickel and cobalt are listed, namely dibutyl monohydrogen phosphate, are practically identical distribution coefficients specified, so that a separation of cobalt and nickel is not possible with it.

It is also a method of obtaining a more concentrated aqueous solution of nickel and / or cobalt from a more dilute solution known (GB-PS 9 70 011), in which a dilute aqueous solution containing nickel or cobalt or both is made alkaline and thereby nickel and / or cobalt are precipitated as hydroxides, the hydroxides then with a solution of an essentially water-insoluble alkyl orthophosphate, alkyl pyrophosphate or alkyl phosphonate in a water-immiscible one organic solvent to form an organic phase containing the metals are treated and the metal-containing organic phase separated from the aqueous phase and used for Obtaining the more concentrated aqueous solution of nickel and / or cobalt with an acid one aqueous solvent is treated. Again, there is no significant separation of cobalt and nickel reached, rather it is an enrichment of cobalt and nickel together without significant Separation of the two components. Must also be

the known process initially carried out a precipitation of cobalt and nickel in the form of hydroxides whereupon the suspension formed containing these hydroxides in the solid phase is subjected to extraction treatment. An extraction treatment of such a suspension brings procedural problems with it and is prone to failure due to the presence of the solid content. For example, care must be taken to ensure that solid fractions do not settle is avoided, and in the case of the settling of solids, which can never be completely ruled out, disturbances can occur due to unintentional changes in flow conditions, contact and concentration phases in contact with one another or blockages occur.

The invention is based on the object of creating a method of the type specified at the beginning, which makes it possible to selectively extract the cobalt from cobalt- and nickel-containing aqueous starting solutions and thereby to bring about an extensive separation between nickel and cobalt, and can nevertheless be carried out simply, economically and not susceptible to failure.

To solve this problem, the invention provides a method for separating cobalt and Nickel from a cobalt and nickel-containing aqueous solution, in which an extraction with a solution of a Organophosphoric acid compound of the general formula

35

O
ROP = O

OH

in which R is hydrogen, an alkyl, aryl or aralkyl group, with the proviso that, if both R are alkyl, aryl, or aralkyl groups, each R contains at least 8 carbon atoms, and when an R Is hydrogen, the other R containing at least 12 carbon atoms, in an inert organic Solvent carried out, the resulting, metal-containing organic extract phase from the remaining aqueous phase is separated and the organic extract phase is worked up to remove metal, which according to the invention is characterized in that from the aqueous solution at a pH from 5.0 to 6.5 the cobalt with an alkali or ammonium salt of organophosphoric acid of the general Formula extracted

The process of the invention succeeds, for example when the extraction is carried out continuously in one Liquid-liquid extraction column, an approximately quantitative separation of cobalt and nickel, such as is also demonstrated below using an example. An acidic starting solution can be processed directly will. A precipitation of cobalt and nickel in the form of hydroxides, as in the known above Process in which, moreover, practically only a joint enrichment of cobalt and nickel without substantial separation of the two components is achieved is not necessary. Difficulty how they can occur during the extraction treatment of a suspension containing solids are excluded.

With a very simple and economical way of working, the cobalt is extracted from the organic extract phase, especially after washing them to remove occluded nickel, and the nickel from the aqueous Raffinate phase in a very pure state, especially as regards cobalt, and in high yield won.

Features and preferred embodiments of the method are further explained below.

An alkali or ammonium salt dissolved in an inert organic solvent is used as the extractant an organophosphoric acid compound of the general formula

ROP = O
OH

in which R is hydrogen, an alkyl, aryl or aralkyl group, with the proviso that, if both R are alkyl, aryl, or aralkyl groups, each R contains at least 8 carbon atoms, and when an R Is hydrogen, the other R containing at least 12 carbon atoms is used. Such connections are practically insoluble in water, which is necessary for the process. The groups R can contain further Substituents, e.g. B. alkoxy or halogen groups, and contain saturated or unsaturated character and / or have heteroatoms, as long as the effectiveness for the extraction of cobalt ions from the aqueous phase is not impaired in the organic phase and the organic phosphate in is soluble in organic solvents and insoluble in water

Some organophosphoric acids that satisfy the general formula above, e.g. B. Di- (2-ethylhexyl) phosphoric acid, have also been used in the prior art procedures noted above, however from the information provided there, the above definition of the group of substances to be used in the process of the invention does not exist and certainly not the use of their alkali metal or ammonium salts in the invention refer to the prescribed pH range.

Examples of suitable compounds for the process of the invention include:

the alkali or ammonium salts of

Di- (2-ethylhexyl) phosphoric acid,

Heptadecyl phosphoric acid,

Dodecyl phosphoric acid,

Di- (l-methylheptyl) phosphoric acid,

Diisooctyl phosphoric acid,

Di- (2-ethyl-4-methylpentyl) phosphoric acid,

Di- (2-propyl-4-methylpentyl) phosphoric acid,

Octylphenyl phosphoric acid, isooctyl or

Stearyl derivatives of acidic alkyl phosphates.
The ammonium salt of di (2-ethylhexyl) phosphoric acid is particularly preferred. It is expedient to use 5 to 40% by volume of the salt.

The extraction takes place at a pH between 5.0 and 6.5; this is due to the buffer effect regulated, which occurs when the alkali or ammonium ions during the extraction of cobalt from the organic phase pass into the aqueous phase. Because of this buffer effect, the aqueous loading

solution have a pH as low as 2.

The inert organic solvent in which the alkali or ammonium salt of organophosphoric acid (hereinafter referred to as extraction agent) is dissolved, must be water-immiscible, the extraction agent dissolve and it must not hinder the extraction of the cobalt. For extraction at elevated temperatures solvents with high flash points are used. Suitable are e.g. B. aliphatic or aromatic hydrocarbons, halogenated hydrocarbons, petroleum derivatives, ethers and mixtures of which, examples are toluene, carbon tetrachloride, benzene, chloroform, methylene chloride, 2-ethylhexanol and in particular called kerosene or naphtha.

Preferably an emulsion inhibitor is included in the solvent or in the extraction solution, i.e. H. that Mixture of extraction and solvent, introduced to prevent the formation of emulsions and to facilitate phase separation. About 3 to 5% tributyl phosphate or isodecanol are for this purpose particularly suitable.

The aqueous solution containing cobalt and nickel can be brought into contact with the extraction solution by any of the known procedures used in liquid-liquid extractions. Continuously operating countercurrent methods are preferred, however batch, continuous batchwise and batchwise countercurrent methods can also be used. Known means for bringing two liquids into contact can be used, e.g. B. a pulsing column or a countercurrent rotating disk column. The temperature at which the extraction is carried out is not important; It is expedient to work in the temperature range from 20 to 70 ^° C., depending on the boiling point of the organic solvent used. Operational tests have shown a better separation at higher temperatures within the above range (see Table D).

The volume ratio of organic phase to aqueous phase can be changed within wide limits will; the most favorable ratio in the individual case can easily be determined by a specialist and depends from the extractant used, the organic solvent and the type of used Solution containing cobalt and nickel as well as its concentration and the extraction method used. Countercurrent methods are usually preferable when the volume ratio is organic Phase to the aqueous phase is low. During operational investigations in a pulsating column z. B. a ratio of aqueous to organic phase of 1: 1 has proven to be very favorable. Generally this will be Ratio adjusted so that there is practically complete absorption of all cobalt in the organic phase allowed into the raffinate with the lowest possible losses of cobalt.

After the cobalt has been extracted into the organic phase and the aqueous phase has been separated from the organic phase, the organic extract phase is introduced into a washing device of known design. In the scrubber, the cobalt-containing organic phase is washed with a solution which contains 10 to 100 g of cobalt per liter in the form of sulfate or nitrate and has a pH of 4.5 to 5.5 in order to wash away nickel which has passed over . It is also possible to treat nickel that has passed over by washing with a dilute mineral acid solution, e.g. B. 0.6 nH ₂ SC> 4 or HNO ₃ , to remove; some cobalt is also taken out. The latter can be recovered by recycling the washing solution to the extraction stage.

After washing, the cobalt-laden organic extract phase is used to separate the cobalt subjected to a stripping treatment carried out in any known liquid-liquid contact device can be. The cobalt-containing organic extract phase is expediently 2 to 30% by volume mineral acid, e.g. B. sulfuric acid, nitric acid or hydrochloric acid, preferably with a 0.5 to 5normal mineral acid brought into contact, choosing the acid from the desired cobalt salt depends.

The acidic starting solution containing cobalt and nickel

• normally contains 0.1 to 50 g / l cobalt and 0.1 to 50 g / l nickel. The loaded organic obtained Extract phase usually contains 5 to 25 g / l cobalt and less than 0.1 g / l nickel. Contains after washing the organic phase 5 to 25 g / l cobalt and less than 0.01 g / l nickel.

The acidic starting solution is produced by leaching the ore containing the metals with an acid. Nitric acid or sulfuric acid are best for this. The content of the acidic is expedient Starting solution made as little as possible of impurities before extraction. Iron, Copper and arsenic can be removed by pH adjustment, precipitation and filtration. It is especially important Remove copper, as copper is extracted preferentially over cobalt. It was found that by Increasing the pH of the solution to 5.3 almost the total amount of copper is precipitated, so that less than 0.01% copper remains in solution.

Operational studies were carried out on the extraction and separation of cobalt and nickel from ores that are made from from the cobalt region of Ontario. A typical ore had the following given analysis:

Table A.

element

Ag

Al

As

Bi.

Approx

Co

Cu

Fe

Mg

Ni

Si

0.06
0.4

54.4
0.22
3.4

10.6
0.11
7.10
0.7
5.36
1.3
0.6

Test series 1

(a) Starting solutions were obtained by acid leaching an ore according to Table A above manufactured. The concentrations of those in solution after removal of copper, iron and arsenic Metals is dependent on the solid / liquid ratio in the leaching and the applied Method for removing copper, iron and arsenic

out of solution. In the following tests, four feed solutions became the following Compositions used: '

Cobalt nickel
g / lg / l

Iron g / l

arsenic

g / l

Loading 1 12.2 14.0 0.058 2.8 Loading 2 11.7 13.4 0.010 1.1 Loading 3 12.1 14.1 0.044 1.1 Loading 4 11.7 13.3 0.017 0.4

IO

(b) Four extraction solutions were also prepared by adding di- (2-ethylhexyl) phosphoric acid to a naphtha

Table B.

tha containing 5% by volume of tributyl phosphate was added. The solutions were then _{treated with Na2CO 3} solution in order to form the sodium salt of the acid in the solutions.

(c) Extractions were carried out using the above charges and extraction solutions as aqueous or organic phases were used. In these investigations the variable was that Amount of the sodium salt of di (2-ethylhexyl) phosphoric acid present in the extraction solution. the Extractions were carried out at pH values of 5 to 6 and a ratio of aqueous to organic phase carried out by 1: 1. The results are summarized in Table B:

Extraction solution, vol .-% d. Loading

Na salt of di- (2-ethyl kung

hexyl) phosphoric acid

Extract, g / l

Co Ni

Raffinate, g / l
Co

Ni

Equilibrium pH

15th 1 ... 3 10.1 3.5 9.5 13.0. 5.5 20th 12.9 5.5 8.5 12.3 5.5 30th 19.5 6.4 6.2 11.6 5.6 40 24.0 9.2 4.4 9.7 5.7 15th 2 4th 10.4 3.5 9.2 12.0 5.0 20th 13.0 5.7 8.0 12.3 5.2 30th 19.0 6.5 5.8 11.3 5.5 40 23.5 8.9 4.1 9.5 5.7 15th Test series 2 11.4 3.3 10.2 13.8 5.4 20th 12.1. 5.1 8.8 12.8 5.4 30th 16.5 ' 5.6 7.0 7.4 5.4 40 21.0 8.4 5.2 10.8 5.5 15th 10.1 3.9 8.4 12.1 5.6 20th 12.6 5.4 7.6 11.6 5.6 30th 18.5 6.3 5.5 10.9 5.6 40 22.0 8.8 3.6 8.8 5.7 Isodecanol and different amounts of Ne
40 salts of Di - ^ - athvlhexvlt-ohosDhorsaure.

A series of tests was carried out to determine the maximum cobalt and nickel loading of various Determine extraction solutions. These extraction solutions were prepared in a manner similar to Test series 1, section (b), produced and consisted of naphtha with a content of 5% by volume These extraction solutions were made with both sulfuric acid and nitric acid leaching solutions which Contained cobalt or nickel, at a pH of 6 and a ratio of aqueous to organic Phase of 1: 1 brought into contact. The results of these studies are summarized in Table C. composed: ■

Table C.

Leach solution

Vol.% Sodium salt of di (2-ethylhexyl) phosphoric acid Maximum load, g / l

Ni

Sulfuric acid

Nitric acid

15 20 30 40

15 20 30 40 15
21
28
32

15th
21
28
33

10
14th
23
26th

10
14th

25th

Test series 3

In order to investigate the influence of temperature on the extraction of cobalt and nickel, Extractions carried out at temperatures between 32 ° and 59 ° C.

An acidic solution was prepared by leaching an ore of the type described in Table A and Iron and arsenic were removed from the solution.

609 539/333

An extracting solution was also prepared which consisted of naphtha as a solvent, 15% by volume of the sodium salt of di (2-ethylhexyl) phosphoric acid and 5% by volume of isodecanol.

The leaching solution and the extracting solution were shaken in Erlenmeyer flasks in one thermostat-controlled water bath with mixing by means of a mechanical shaker with swiveling

10

brought into contact with each other. The ratio of aqueous to organic phase was 2: 1 and the contact time was 10 minutes. The results shown in Table D show that increasing Temperatures at increased cobalt loading with a concomitant decrease in the amount of extracted nickel to lead.

Table D.

Temperature,
⁰ C

Extract, g / l Co

Equilibrium
PH

32 6.8 1.1 5.4 6.7 1.3 5.4 42 7.6 0.4 5.4 7.7 0.5 5.4 • 50 8.0 0.2 5.5 8.1 0.3 5.5 59 10.3 0.2 5.5 Test series 4 . results
_ j. Λ Γ / 1 show,

The washing process was carried out using a solution of 15% by volume of the sodium salt of di (2-ethylhexyl) phosphoric acid in naphtha as a solvent, which contained cobalt and nickel, investigated. As washing solutions cobalt nitrate and cobalt sulfate solutions each containing about 20 g Co / l were used. In the In the first series of tests, the organic phase contained 5% by volume isodecanol, with 8.4 g / l cobalt or 4.5 g / l nickel. Those listed in Table E contained about 1.5 g / l Ni. In a second series of experiments an organic phase was used which contained 5% by volume of tributyl phosphate with 12.9 g / l cobalt or 3.8 g / l nickel contained. The washing tests showed that the nickel content in the extract was less than 0.05 g / l was decreased. The cobalt sulfate solution is a little more effective than the nitrate solution. In all examinations the ratio of aqueous to organic phase was 5: 1 and the contact time was 10 minutes Room temperature.

Table E.

Washing solution

number of
contacts

Emulsion inhibitors

Extract, g / l
Co

Ni

Raffinate, g / l Ni Co 0.80 20.1 0.80 20.6 0.20 20.8 0.80 20.2 0.20 21.4 0.10 21.2 0.8 26.0 0.2 27.0 0.2 26.8 0.2 26.3 0.8 26.3 0.8 26.1 0.2 25.9 0.8 25.2 0.2 26.0 0.2 25.5

CO (NO3) 2

(20 g Co / 1)

COSO4
(27 g Co / 1)

Co (NCb) ₂
(26 g Co / 1)

1 ' Isodecanol 20.8 1) the same - 2) the same 21.6 1) the same - 2) the same - 3) the same 22.4 1 Tributyl phosphate 16.0 1) the same - 2) the same 16.1 1) the same - 2) the same - 3) the same - 1 the same 16.2 1) the same - 2) the same 16.3 1) the same - 2) the same - 3) the same 16.2 Test series 5 cobalt

Operational tests were conducted to determine whether washing with an aqueous Cobalt sulfate solution can remove large amounts of nickel from an organic phase, both

65 2.0

1.5

1.4
0.1

0.04

0.03
0.2

0.1
0.08

Contains both cobalt and nickel. An organic phase with a content of 9.5 g / l nickel and 3.2 g / l cobalt was treated with an aqueous cobalt sulfate solution containing 28.6 g / l of Co at a ratio of aqueous brought into contact with an organic phase of 1: 1 for a period of 5 minutes. The percentage

Nickel removal at 20, 40, 60 and 70 ⁰ C was 45, 65, 75 or 80%.

An increase in the cobalt concentration in the washing solution resulted in an increase in the amount of Nickel removed per contact.

The influence of the ratio of aqueous to organic phase was also examined. the Results showed that with a ratio of aqueous to organic phase of 1: 1, more than 95% of the nickel were removed after 3 contacts, while at ratios of 1: 5 and 1:10 after 3 contacts 67 and 32% of the nickel was removed, respectively. It was also found that isodecanol at elevated temperatures no adverse effect (cf. Table E) on the removal of nickel from the loaded extract by washing.

Table F.

Test series 6

Stripping tests were carried out with an extract of 20% by volume of the sodium salt of Di- (2-ethylhexyl) phosphoric acid, 5% by volume isodecanol and naphtha, the 8.4 g / 1 cobalt and 4.5 g / l nickel contained, carried out. 1, 5 and 10 percent by volume nitric acid and 1 percent by volume were used as stripping solutions Sulfuric acid and 5 volume percent hydrochloric acid are used. In each case the ratio was from aqueous to organic phase 1: 1 and the contact time 10 minutes. Those listed in Table F. Results show that both cobalt and nickel are easily removed from the acid using these acids organic extract phase are stripped off.

Stripping solution
acid

Stripping Aqueous solution obtained, g / l Co Ni

Stripped extract, g / l
Co Ni

ENT3

1 1 2.0 2.2 <0.02 <0.01 2 2.9 1.5 3 3.0 0.5 <0.02 <0.01 5 1 8.5 4.2 2 0.2 0.08 <0.02 <0.01 10 1 8.2 4.0 2 0.1 0.05 1 1 4.9 3.3 <0.02 <0.01 2 . 3.2 0.7 3 '0.09 0.02 <0.02 <0.01 5 1 8.9 4.8 2 0.36 0.2

H2SO4

example

A continuous extraction of a nitric acid starting solution was carried out by Leaches of ore according to Table A had been obtained with nitric acid.

The extraction takes place in a 12.2 m high pulsating column using an extraction solution from 30% by volume of 1% di (2-ethylhexyl) phosphoric acid, 5% by volume tributyl phosphate and 65% naphtha. From the The starting solution was initially the main amount of the arsenic contained in it by adding iron (III) sulfate and precipitation of ferric arsenite in one

Table G.

pH 2.5 removed. The extraction solution was equilibrated with ammonia, namely with 6% by volume ammonium hydroxide solution, the ammonia dissolving in the organic phase. the Extraction was performed at 60 ° C ± 3 ° C.

The loading of the organic extract phase was 21.5 g / l Co and 0.48 g / l Ni. The cobalt recovery was 97.8%. The loaded organic extract phase could easily be stripped off with 1.6 η ΗΝΟ3.

The flow of the aqueous phase through the column was 10.0 l / h.

Further details of the extraction are given in Table G.

Ratio of material Organic phase, g / l Fe Watery Phase, g / l Fe pH aqueous phase to organic phase Co Ni As Co Ni As

aqueous

Charge.

laden

organic

Extract phase

Raffinate

21.6

14.3

21.5

0.48

0.50 12.2

0.46

0.5

<0.01 3.5

<0.01 53

Part of the loaded organic extract phase, which was 65 and had a pH of 4.5. The nickel content in

21.5 g / l cobalt and 0.48 g / l nickel was contained in the organic extract phase was reduced to less than

a 6.1 m high pulsing column with a cobalt solution of 0.02 g / l Ni,

solution that contained 40 g / l Co as cobalt sulfate.

phase were with 0.6 η nitric acid or sulfuric acid with a ratio of aqueous to organic Phase 1: 4, washed with sulfuric acid also at a ratio of 2:15. The resulting

Wash liquid can be returned to the feed for extraction. Results of these ablutions are listed in Table H.

Table H.

Ratio of aqueous to organic phase

Washing liquid Co Ni

Washed organ. Co Ni extract phase

(g / l) (g / l)

(g / l)

(g / l)

0.6 n-HNO3
0.6 n-H2SO4
0.6 n-H2SO4

1: 4
Ϊ: '4
2:15

25.0 1.74 12.9 0.063 27.3 1.69 14.4 <0.010 26.8 2.22 18.4 <0.05

The washed organic extract phases from the above washing treatments were stripped in a stripping column with 10% HNO ₃ at 45 ° C. and the resulting aqueous solution was evaporated to obtain cobalt nitrate.

Claims (1)

Patent claims: 1. Process for the separation of cobalt and nickel from an aqueous cobalt and nickel containing one Solution in which an extraction with a solution of an organophosphoric acid compound of the general formula