RU2052519C1 - Method for cleaning aqueous cobalt solutions from nickel - Google Patents

Abstract

FIELD: hydraulic metallurgy of nonferrous metals. SUBSTANCE: method involves extraction of nickel by mixture of carboxilated tetraalkylammonium and nonchelating oximes; rinsing extract from cobalt by water and conducting reextraction of nickel by aqua-ammonia solutions. EFFECT: increased efficiency in removal of nickel from cobalt solutions. 5 tbl

Description

 The invention relates to hydrometallurgy of non-ferrous metals and processes for the production of cobalt salts and can be used in the processing of various cobalt-containing products, in particular solutions after leaching of cobalt hydroxide, cobalt cake, manganese nodules, as well as solutions to obtain cobalt salts, etc.

 The need to create the present invention is determined by the complexity of existing technological schemes for the purification of cobalt solutions from nickel, the high consumption of reagents (acid, alkali, extractants) in the cleaning process.

 A known method of purification of cobalt solutions from impurities, including nickel, using carboxylic acids.

The disadvantage of this method is the low efficiency of the extractant β _{Ni / CO} ≃ 1.6-1.8 which leads to a large number of stages during extraction (n more than 50) and a high consumption of alkali and acid per 1 ton of obtained cobalt.

 In another method, the purification of cobalt solutions from nickel is carried out by phosphorus-organic acids. In this case, mainly cobalt is extracted. At a high concentration of cobalt in the solution, since the macrocomponent is extracted, a large amount of alkali is consumed for extraction in order to extract it, as well as mineral acid at the stage of reextraction. The flows of extractant and stripping solution increase, as well as the volume of extraction and auxiliary equipment.

 The closest in technical essence and the achieved effect to the claimed method is a method in which the extraction purification of cobalt solutions from nickel is carried out with mixtures of carboxylic acids and non-chelating oximes, while mainly nickel is extracted. For washing extracts from cobalt and re-extraction of nickel, it is necessary to use solutions of mineral acids.

+ H

R-C

+ [NH₃OH] $\genfrac{}{}{0ex}{}{\text{+}}{\text{(в)}}$ (1) необходимость использования дорогостоящей кислото-упорной коррозионноустойчивой аппаратуры.The disadvantages of the method: high consumption of alkaline solutions (sodium hydroxide or ammonia) for extraction to maintain the pH of aqueous solutions; significant consumption of mineral acids at the stages of washing the extracts from cobalt and re-extraction of nickel; partial degradation of the oxime and its loss upon contact with mineral acids in accordance with reaction (1), especially when using hydrochloric and nitric acids:
RC

+ H

RC

+ [NH ₃ OH] $\genfrac{}{}{0ex}{}{\text{+}}{\text{(in)}}$ (1) the need to use expensive acid-resistant corrosion-resistant equipment.

 The purpose of the invention is to simplify the process of purification of cobalt solutions from nickel due to the complete elimination of the use of mineral acids at the stages of washing the extracts from cobalt and re-extraction of nickel, to reduce oxime losses (1), to reduce the consumption of alkaline reagent, to simplify hardware design by using cheaper structural materials, since mineral acids are not used in the process.

 This goal is achieved in that, in contrast to the known method for cleaning cobalt solutions of nickel, including the extraction of nickel with a mixture of carboxylic acid and a non-chelating aldoxime of simple structure with the need for further washing of the extract from cobalt and re-extraction of nickel with mineral acid solutions, in the proposed method instead of carboxylic acid for extraction in a mixture with a non-chelating aldoxime, tetraalkylammonium carboximate is used as the carbon compound. The washing of the organic phase from cobalt is carried out with water, and the re-extraction of nickel with aqueous ammonia solutions.

NA_(o)+NaOH

R

NR_(o)+NaA_(в)+H₂O (2) где НR монокарбоновая кислота,
R'₄NA соль четвертичного аммониевого основания, где А хлорид или сульфат-ионы,
(о) и (b) органическая и водная фазы, соответственно.Aldoximes are the condensation products of aldehydes with hydroxylamine, which easily proceeds in an aqueous or alcoholic solution. The extractant is prepared by simple mixing of the starting reagents and processing the mixture with an alkali solution in a stoichiometric ratio (1.0 M sodium hydroxide solutions were used) according to the reaction:
HR _(o) + R

NA _(o) + NaOH

R

NR _(o) + NaA _(c) + H ₂ O (2) where HR is monocarboxylic acid,
R ' ₄ NA salt of the Quaternary ammonium base, where a chloride or sulfate ions,
(o) and (b) organic and aqueous phases, respectively.

NR_(o)+Ni $\genfrac{}{}{0ex}{}{\text{2+}}{\text{(в)}}$ +2Cl $\genfrac{}{}{0ex}{}{\text{-}}{\text{(в)}}$ +4Ox

Ni(Ox)₄R_2(o)+2R

NCl_(o) (3) где Ох альдоксим. По аналогичной реакции (3) экстрагируется также и кобальт, но со значительно меньшими коэффициентами распределения;
отмывка экстракта от кобальта водой:
Co(Ox)₄R_2(o)+2R

NCl

2R

NR_(o)+4Ox_(o)+Co $\genfrac{}{}{0ex}{}{\text{2+}}{\text{(в)}}$ +2Cl_(в) (4)
реэкстракция никеля растворами аммиака:
Ni(Ox)₄R_2(o)+2R

NCl_(o)+nNH₄OH

Ni(NH₃) $\genfrac{}{}{0ex}{}{\text{2+}}{\text{4(в)}}$ +
+2Cl $\genfrac{}{}{0ex}{}{\text{-}}{\text{(в)}}$ +R

NR_(o)+4 Ox_(o)+nH₂O (5)
Из уравнений (3-5) видно, что в процессе не используются минеральные кислоты, в отличие от прототипа. В результате существенно уменьшаются потери альдоксима за счет его разложения, поскольку основные потери связаны с его кислотной деградацией. Так как исключается применение минеральных кислот, возможно использование доступных и дешевых материалов для аппаратурного оформления процесса (обыкновенная или нержавеющая стали и др.).In the proposed method, the following process steps are implemented:
Nickel extraction (for example, chloride solutions):
2R

NR _(o) + Ni $\genfrac{}{}{0ex}{}{\text{2+}}{\text{(in)}}$ + 2Cl $\genfrac{}{}{0ex}{}{\text{-}}{\text{(in)}}$ + 4Ox

Ni (Ox) ₄ R _{2 (o)} + 2R

NCl _(o) (3) where Oh aldoxime. By a similar reaction (3), cobalt is also extracted, but with much lower distribution coefficients;
washing the extract from cobalt with water:
Co (Ox) ₄ R _{2 (o)} + 2R

Ncl

2R

NR _(o) + 4Ox _(o) + Co $\genfrac{}{}{0ex}{}{\text{2+}}{\text{(in)}}$ + 2Cl _(c) (4)
re-extraction of nickel with ammonia solutions:
Ni (Ox) ₄ R _{2 (o)} + 2R

NCl _(o) + nNH ₄ OH

Ni (NH ₃ ) $\genfrac{}{}{0ex}{}{\text{2+}}{\text{4 (c)}}$ +
+ 2Cl $\genfrac{}{}{0ex}{}{\text{-}}{\text{(in)}}$ + R

NR _(o) +4 Ox _(o) + nH ₂ O (5)
From equations (3-5) it can be seen that mineral acids are not used in the process, unlike the prototype. As a result, the loss of aldoxime due to its decomposition is significantly reduced, since the main losses are associated with its acid degradation. Since the use of mineral acids is excluded, it is possible to use accessible and cheap materials for instrumentation of the process (ordinary or stainless steel, etc.).

From equation (2) it is also seen that due to the formation of a binary extractant R ' ₄ NR, washing the extract from cobalt is easily carried out with water, which is not possible according to the prototype. This eliminates the flushing of reagents such as mineral acids and chloride ion. For re-extraction of Nickel by the proposed method, in contrast to the known, it is not necessary to use solutions of mineral acids, which contributes to the stability of the oxime, saving reagents and reduces the risk of corrosion damage to the equipment. For reextraction, alkaline solutions, in particular aqueous ammonia solutions, can be used.

 The regeneration of the extractant coincides with the stage of nickel reextraction with ammonia solutions (5). The obtained extractant does not require preparation for further use in the extraction process. Since cobalt is previously completely re-extracted with water, the alkaline reagent (in this case, ammonia water) is spent only on nickel, while in the prototype, the alkali consumption is both nickel and cobalt.

EXAMPLE 1. From a chloride solution containing various concentrations of cobalt and nickel, extraction was performed with a 0.5 M solution of trialkylbenzylammonium carboxylate in a mixture with a 1.0 M solution of enantaldoxime in toluene (carboxylate anion of α-branched higher VIC iso acids, fractions C ₅ -C ₁₁ , alkyl in trialkylbenzylammonium C ₇ -C ₉ ); O: B 1: 1; α 30 min, pH of the _original solution 4.1. The experimental results are shown in table 1.

A sufficiently high nickel distribution coefficient (D _Ni ) and nickel-cobalt separation coefficient (β _{Ni / Co} ) are _achieved . These values depend little on the cobalt-nickel ratio in the initial solution.

PRI me R 2. Analogously to example 1 (sample 3), an extract was obtained containing, g / DM ³ : cobalt 4.4; nickel 3.43. It was washed with water at various ratios of aqueous and organic phases (O: B) for 3 minutes. The data on the washing of extracts from cobalt are given in table.2. As can be seen from table 2, cobalt is quite simply extracted with water from the organic phase. The optimal ratios of the organic and aqueous phases can be considered O: B 3-6: 1. Since when the ratio O: B is less than 3: 1, the flow rate of washing water will increase unnecessarily, which will lead to dilute cobalt solutions, and when O: B is greater than 6: 1, washing from cobalt worsens, which leads to an increase in the number washing steps.

For comparison, analogously to example 1 (sample 3), an extract was obtained after extraction with a 1.2 M solution of enantaldoxime in monocarboxylic acids of the C ₇ -C ₉ FFA fraction (prototype), the pH of the equilibrium solution was 3.1. The obtained extract contained, g / dm ³ : cobalt 6.1; nickel 4. It was treated with water at O: B 1: 1 (conditions are similar to sample 3 in this example). After washing, it was found in the aqueous phase, g / dm ³ : cobalt 0.08; Nickel 0.02. Washing the extract from cobalt, and especially nickel with water, practically does not occur.

EXAMPLE 3. To study the re-extraction of nickel from a saturated solution of nickel chloride, nickel was extracted (the composition of the extractant is shown in example 1) at O: B 1: 1, τ 10 min. The resulting extract contained 14.0 g / DM ³ Nickel. For reextraction of nickel, it was treated with aqueous solutions of ammonia of various concentrations at O: B 1: 1, τ 20 min. Reextraction data are given in table 3.

As can be seen from table 3, the reextraction of Nickel is quite complete in a wide range of concentrations of ammonium hydroxide. For specific cases, the flow rate of the ammonia solution (the concentration of ammonium hydroxide and the O: B ratio) largely depends on the nickel content in the organic phase. So, with a decrease in the concentration of nickel in the organic phase, the consumption of ammonia will decrease. The consumption of an alkaline reagent, in this case ammonium hydroxide, in the proposed method is significantly less than in the prototype, since in the proposed method, NH ₄ OH is spent only on re-extraction of nickel, while in the known method, alkali (NaOH or NH ₄ OH) is consumed as extraction nickel, so partially and cobalt.

PRI me R 4. In laboratory conditions, the technological scheme of purification of cobalt chloride solution from nickel by simulating countercurrent extraction, washing the extract from cobalt and nickel re-extraction was checked. The composition of the initial aqueous solution, g / DM ³ : cobalt 90.1; nickel 5.1, pH _ref 4.1. The extractant composition is shown in Example 1. Nickel was extracted at O: B 1: 1, the number of steps was n 10, the extract was washed from cobalt with water at O: B 4: 1, n 5, and nickel was re-extracted with aqueous ammonia solutions with a concentration of NH ₄ OH 1.0 M at O: B 4: 1, n 3. The nickel content in the raffinate was 0.008 g / dm ³ , the cobalt content in the washed extract was 0.02 g / dm ³ , and the nickel was 4.08 g / dm ³ . The nickel content in the organic phase after reextraction was 0.005 g / dm ³ , cobalt was not detected. The concentration of Nickel in the reextract 16.3 g / DM ³ . In a closed cycle, extraction, washing of the extract, re-extraction, cleaning of solutions from nickel and regeneration of the extractant are achieved in a small number of steps without the use of mineral acids. Alkaline reagent (ammonia solution) is consumed only on the re-extraction of Nickel.

PRI me R 5. From a nitrate cobalt solution containing g / DM ³ cobalt 60; nickel 6, extraction was carried out at O: B 1: 1 with trialkylmethylammonium carboxylate (R ' ₄ NR) of various concentrations in a mixture with 1.0 mol / dm ³ solution of nonanaldoxime in toluene (carboxylate anionic acid anion, alkyl into trialkylmethylammonium radical C ₇ -C ₉ , τ 15 minutes, the results of the experiments are given in table 4.

As can be seen from Table 4, the distribution coefficients of nickel D _Ni and the separation of nickel and cobalt β _{Ni / Co are} quite high in the entire range of trialkylmethylammonium carboxylate concentrations. With a decrease in the concentration of extractant, a decrease in nickel extraction is observed, however, the separation of nickel and cobalt remains good. In specific cases, the concentration of tetraalkylammonium carboxylate will be determined by the conditions of use: the concentration of cobalt and nickel in the initial solution, etc.

 PRI me R 6. Analogously to example 5, extracts containing various amounts of cobalt (and nickel) are obtained. They were washed with water at an organic: aqueous phase ratio of O: B 2: 1 for 3 minutes. The data on the washing of extracts from cobalt are given in table 5.

As can be seen from table 5, washing is quite effective, however, when the concentration of trialkylmethylammonium carboxylate is more than 0.6 M, the degree of washing is somewhat worse. The degree of nickel washing with water (together with cobalt) did not exceed 5.0%
EXAMPLE 7. Nickel was extracted from a saturated solution of nickel nitrate with a 0.5 M solution of trialkylmethylammonium enanthate (C ₇ -C ₉ alkyl) in a mixture with a 1.0 M solution of nonanaldoxime in toluene at O: B 1: 1, τ 10 min. The extract obtained, containing 14.9 g / dm ^{3 of} nickel, was treated with aqueous ammonia, the concentration of NH ₄ OH was 1.0 mol / dm ³ , O: B 1: 1, τ 20 min. Found in the aqueous phase of Nickel 12.96 g / DM ³ in the organic phase of 1.04 g / DM ³ . Thus, the degree of reextraction in one step was 87%, which makes it possible to reextract nickel almost completely in a multistage process.

PRI me R 8. From a sulfate solution containing, g / DM ³ : cobalt 78; nickel 5.1, extraction was performed with 0.5 mol / dm ³ solution of trialkylbenzylammonium caprylate in a mixture with 1.5 mol / dm ³ solution of 2-methyldecanaldoxime in xylene, O: B 1: 1, τ15 min. Found after extraction, g / dm ³ : in the aqueous phase: nickel 1.82; cobalt 76.02, in the organic phase: nickel 3.28; cobalt 76.02. in the organic phase: nickel 3.28; cobalt 1.38. Thus, D _Co 0.018 and D _Ni 1.8, and the separation coefficient of nickel and cobalt β _{Ni / Co} 100. The separation is very effective.

PRI me R 9. The stability of the oxime in the extractant after contact with alkaline (the proposed method) and acidic (prototype) solutions. Extractant: 0.5 M solution of trialkylbenzylammonium caprylate in a mixture with 1.0 M solution of enantaldoxime in toluene was contacted with 1N (gEq / dm ³ ) with a solution of ammonium hydroxide for 24 hours, O: B 2: 1, t 22 ^о С. After the experiment, the concentration of oxime remained practically unchanged and amounted to 0.995 mol / dm ³ . For comparison, under the same conditions, a 1.0 M solution of enantaldoxime in caprylic acid was contacted with 1.0 N solutions of sulfuric, hydrochloric and nitric acids. After the experiment, the concentration of oxime in the organic phase was 0.92, 0.86 and 0.82 mol / dm ³ , respectively. In the latter case (the use of mineral acids), the decomposition of oxime is much greater.

 The above examples confirm the effectiveness of the proposed method for the purification of cobalt solutions from nickel. Nickel is extracted with tetraalkylammonium carboxylates with high separation coefficients from cobalt from chloride, sulfate and nitrate solutions. Coextracted cobalt is easily removed by washing the extract with water, and nickel is re-extracted with aqueous ammonia solutions almost completely in one or two steps. At the same time, regeneration of the extractant occurs. Reagent consumption is significantly reduced. The degree of degradation of oxime in the proposed method is significantly lower than under the conditions of acid washing and reextraction of metals.

Claims (1)

 METHOD FOR CLEANING AQUEOUS COBALT SOLUTIONS FROM NICKEL, including the extraction of nickel with a mixture of a carbon compound and non-chelating oximes, washing the extract from cobalt and stripping nickel, characterized in that tetraalkyl ammonium carboxylate is used as a carbon compound, and the extract is washed with nickel-water and re-extracting with nickel and water ammonia solutions.

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