RU2378400C2 - Extraction method of nickel from sulfate solutions with high content of calcium and magnesium - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention can be used at reprocessing of sulfate solutions of leaching of oxydised nickel ores (ONO), deep-sea burs, sulfide raw materials, containing calcium and magnesium, extraction. In the result of which it is possible cleaning of extract from admixtures of calcium and magnesium by small volume of washing solution of sulfuric acid without formation of sediments of calcium sulfate (mineral white). Nickel is extracted from solutions with high content of calcium and magnesium by extraction by high iso-carboxylic acids (ICA) in diluent at presence of β-diketon (1-phenyl -1,3-decandion) (LIX 54). Extraction is implemented at pH = 6.1-6.5 and molar ratio ICA : LIX 54 = 1:1÷0.5. Cleaning of extract from admixtures and backwash of nickel is implemented by solutions of sulfuric acids.

EFFECT: increasing of nickel selectivity over admixtures of Ca and Mg at selective extraction of nickel.

7 tbl, 6 ex

Description

The invention relates to hydrometallurgy of non-ferrous metals and can be used in the processing of leach solutions of oxidized nickel ores (OHP), oceanic nodules, sulfide raw materials, etc.

The need to create the present invention is caused by the complexity of existing methods for the extraction of Nickel from sulfate solutions containing impurities of magnesium and calcium, especially in the case of their high concentrations.

The known method [Method for the extraction of Nickel from solutions and pulps containing magnesium and / or manganese. I.A. Logvinenko, L.A. Marushinskaya and others. RF patent No. 20022825; IPC S22V 3/24, publ. 11/15/93; bull. No. 41-42], according to which the extraction of nickel from solutions and pulps after leaching of ore raw materials and its separation from magnesium is carried out using ion-exchange processes. As a sorbent, vinyl pyridine ampholyte containing a carboxyl group is used. Nickel desorption is carried out with solutions of mineral acids (H ₂ SO ₄ , Hcl) to obtain solutions containing 10-25 g / l of Nickel.

The disadvantages of the method are the slow kinetics of sorption and desorption of Nickel, as well as the inability to obtain concentrated Nickel eluates (not more than 25 g / l).

There is also a known method [I. Mihaylov, E. Krause, D. F. Colton, Y. Okita, J.-P. Duterque, J.-J. Perraud. The development of a novel hydrometallurgical process for nickel and cobalt recovery from Goro laterite ore. (2000), CIM Bulletin, Vol. 93, No. 1041, p. 124-130], in which nickel is extracted from sulfate solutions with a high content of magnesium and calcium using di (2,4,4) trimethylpentyldithiophosphinic acid as an extractant (Cyanex 301).

From the initial solution of leaching of oxidized nickel ores (OHP), containing, g / l: 3-6 Ni; up to 0.6 Co; up to 3.0 Mn; up to 0.6 Ca and 1-10 Mg, nickel is extracted with a 15% solution of Cyanex 301 in an aliphatic diluent at a temperature of 55 ° C. Nickel recovery is> 99.5%. Extraction of calcium and magnesium is practically absent. In order to avoid oxidation of the extractant to disulfide with atmospheric oxygen, the extraction is carried out in a stream of inert gas (nitrogen or carbon dioxide). Reextraction of Nickel is carried out with concentrated solutions of hydrochloric acid (6-7 mol / l) at a temperature of 60 ° C.

Significant disadvantages of the method are:

- the need for processes of extraction and reextraction at elevated temperatures (55-60 ° C), which leads to increased energy costs;

- the need for extraction in an inert atmosphere, which significantly complicates the hardware design process;

- the use of concentrated solutions of aggressive hydrochloric acid at the stage of re-extraction increases the cost of the process not only due to the cost of the acid itself, but also because of the need to use special corrosion-resistant materials in the process equipment.

In the method of [J.S. Preston, A.C. Du Preez Separation of nickel and calcium by solvent extraction using mixtures of carboxylic acids. "Hydrometallurgy" (2000), 58, No. 3, p.239-250] it is proposed to extract nickel from sulfate solutions using a synergistic mixture of Versatic 10 (branched monocarboxylic acid) and alkylpyridines as extractant. From solutions containing, g / l: 5.0 Ni; 0.5 Co; 2.0 Mn; 0.5 Ca and 5.0 Mg, Ni recovery was> 99%, coextraction of Ca 1.3% and Mg <0.04%. Reextraction of metals was carried out with a solution of sulfuric acid, while the degree of reextraction was> 98%.

Despite the satisfactory performance of the method for the separation of nickel and alkaline earth elements, it is not free from disadvantages, among which the most significant are:

- coextraction of sulfuric acid at the stage of re-extraction of Nickel, which leads to increased consumption of the catalyst at the extraction stage;

- the complexity of the synthesis and industrial inaccessibility of alkylpyridines.

The closest in technical essence and the achieved result to the claimed method is a prototype method [A.V. Nikolaev, A.I. Kholkin, L.M. Gindin, R.Kh. Freidlin, K.S. Luboshnikova, L.M. Kuznetsova, A.B. Terentyev, Extraction of metals by α, α-dialkyl monocarboxylic acids. Proceedings of the Siberian Branch of the Academy of Sciences, Series of Chemical Sciences, (1972), No. 12, issue 5, pp. 52-58]. According to this method, the extraction of nickel and its separation from calcium and magnesium is carried out using higher isocarboxylic acids (VIC), which are branched monocarboxylic acids - (R ₁ ) (R ₂ ) (R ₃ ) C-COOH with the total number of carbon atoms (R ₁ + R ₂ + R ₃ ) = 5-19 C. Extraction is carried out in the range of pH 6.0-6.5, while the separation coefficients of nickel and calcium (β _{Ni / Ca} ) are 30-40, and nickel and magnesium (β _{Ni / Mg} ) - 300-500. (As can be seen, the separation of nickel and magnesium in these systems is a simpler problem than the separation of nickel and calcium.) Nickel reextraction from the organic phase is easily carried out with sulfuric acid solutions.

A significant disadvantage of the method is that with a high content of calcium in the initial solution (0.5 g / l and higher) due to the low selectivity in nickel extraction (β _{Ni / Ca} = 30-35), there is a noticeable coextraction of calcium. As a result, gypsum can be precipitated at the stage of washing the extract from impurities (Ca, Mg) or on the re-extraction of nickel with sulfuric acid solutions. This creates big problems with the process and leads to nickel losses. To avoid precipitation, the saturated nickel extract must be washed from impurities (Ca and Mg) with a large stream of an aqueous solution of sulfuric acid due to the low solubility of calcium sulfate, which leads to an increase in the volume of extraction equipment, as well as dilution of the total solution, since the washing solution combines with the original .

The technical result of the invention is to increase the selectivity of the extraction of Nickel over impurities during its extraction (mainly, an increase in β _{Ni / Ca} ), while the content of Ca (Mg) in the saturated nickel extract decreases. As a result, it is possible to wash the extract from these impurities with a small volume of a washing solution of sulfuric acid (in fact, acidified with water) without the formation of precipitation of calcium sulfate (gypsum).

This goal is achieved in that, in contrast to the known method for the extraction of nickel from sulfate solutions containing calcium and magnesium, including the extraction of nickel at pH 6.1-6.5 with higher isocarboxylic acids (VIC) in a diluent, washing the extract from impurities with sulfuric solutions acids and nickel stripping with sulfuric acid solutions, the process is carried out in the presence of LIX 54 (β-diketone, 1-phenyl-1,3-decandion), with a molar ratio of VIC: LIX54 = 1: 1 ÷ 0.5.

The improvement in the separation of nickel and Ca (Mg) by mixtures of extractants is due to the manifestation of a synergistic effect during nickel extraction, apparently due to the formation of a triple nickel complex in the organic phase (Ni-BHK-LIX54), and some deterioration of calcium extraction compared to individual extractants.

Branched monocarboxylic acids with at least 5 carbon atoms can be used as isocarboxylic acids (VIC), in particular, fractions C ₅ -C ₁₁ and C ₁₁ -C ₁₉ .

LIX 54 is beta-diketone (1-phenyl-1,3-decandion) and is commercially available [LIX54 ^® -100, Technical Bulletin, Cognis Corporation (USA)].

It is proposed to use mixtures with a molar ratio of VIC: LIX54 = 1: 1 ÷ 1: 0.5 and the pH of the solutions at the extraction stage is 6.1-6.5. At different ratios of VIC: LIX 54, nickel extraction and metal separation (Ni-Ca) deteriorate.

At pH <6.1, nickel extraction deteriorates; at pH> 6.5, nickel recovery increases slightly, but the extraction of impurities noticeably increases.

As solvents, ordinary solvents from a number of aliphatic hydrocarbons (decane, kerosene, oil paraffins, etc.) are used.

The following are examples of the proposed method.

Example 1

Table 1 shows the dependences of the extraction of nickel, as well as the main impurities (Ca and Mg), on the final pH values of the aqueous phases upon extraction with a mixture of VIC (C ₅ -C ₉ fraction) and LIX 54 in kerosene. The change in pH was regulated by introducing various amounts of solutions of ammonium hydroxide into the system. The compositions of the extractant and the initial aqueous solution, as well as the experimental conditions are given in table 1. For comparison, table 2 shows the data on the extraction of VIC metals in kerosene without LIX 54 (prototype method).

Table 1
The dependence of metal extraction on pH with a mixture of VIC and LIX 54 in kerosene
Extractant: 1.0 M VIC (fraction C ₅ -C ₉ ) +1.0 M LIX 54
The initial aqueous solution, g / l: Ni - 4.75; Ca - 0.5; Mg 7.12; pH _(ref) = 6.1
Extraction conditions; T = 22 ° C, τ = 1 h, O: B = 1: 1 pH the content of Ni, g / l * D _Ni Ca content, mg / l D _ca Mg content, g / l D _Mg ** β _{Ni / Ca} β _{Ni / Mg} aqu.f org.f aqu.f org.f aqu.f org.f 4.98 2.75 1.88 0.68 - - 5.58 0.75 3.86 5.15 486 45 0.09 7.0 0.013 0.002 57 2575 6.08 0.125 4.38 35.0 475 57 0.12 7.0 0.056 0.008 292 4375 6.51 0,026 4,53 174.3 462 75 0.16 6.5 0.265 0,041 1089 4252 6.84 0.017 4.86 285.9 420 84 0.20 - - - 1430 - * D = С (org.) / С (в.) - metal distribution coefficient; ** β _{Ni / Ca} = D _Ni / D _Ca - Ni-Ca separation coefficient; β _{Ni / Mg} = D _Ni / D _Mg - Ni-Mg separation coefficient

table 2
The dependence of metal extraction on the pH of the VIC in kerosene
Extractant: 1.0 M VIC (fraction C ₅ -C ₉ )
The initial aqueous solution, g / l: Ni - 4.75; Ca - 0.5; Mg 7.12; pH _(ref) = 6.1
Extraction conditions; T = 22 ° C, τ = 1 h, O: B = 1: 1 pH the content of Ni, g / l D _ni Ca content, mg / l D _ca Mg content, g / l D _Mg β _{Ni / Ca} β _{Ni / Mg} aqu.f org.f aqu.f org.f aqu.f org.f 5.75 2,30 2.25 0.98 460 56.0 0.12 7.0 0,038 0.005 8.1 196 6.2 1.13 3,50 3,1 427 73.0 0.17 7.0 0,055 0.008 18.2 398 6.6 0.56 4.13 7.38 406 90.0 0.22 7.0 0,094 0.014 33.6 527 6.93 0.44 4.25 9.66 365 113.5 0.31 - - - 31,2 - D = C (org.) / C (century) - metal distribution coefficient; β _{Ni / Ca} = D _Ni / D _Ca is the separation coefficient of Ni-Ca; β _{Ni / Mg} = D _Ni / D _Mg - Ni-Mg separation coefficient

From table 1 it is seen that in the proposed method, the extraction of Nickel (D _Ni ) and the degree of its separation from impurities (β _{Ni / Ca} and β _{Ni / Mg} ) is much higher than in the known method (prototype) (see table 2 )

From table 1 it is also seen that with increasing pH, the extraction of nickel increases, the optimal range of extraction should be considered a change in pH in the range of 6.1-6.5. At pH <6.1, nickel extraction noticeably worsens; at pH> 6.5, nickel recovery increases slightly, however, the extraction of calcium and magnesium increases markedly.

Example 2

The following example demonstrates the possibility of using for the purification of nickel from Ca and Mg not only a mixture of LIX 54 with VIC fractions C ₅ -C ₉ (example 1), but also other VIC fractions.

Table 3 shows the dependences of the extraction of nickel, as well as the main impurities (Ca and Mg), on the final pH values of the aqueous phases upon extraction with a mixture of VIC (fraction C ₁₁ -C ₁₉ ) and LIX 54 in kerosene. The experimental conditions are similar to example 1.

Table 3
The dependence of metal extraction on pH with a mixture of VIC and LIX 54 in kerosene
Extractant: 1.0 M VIC (fraction C ₁₁ -C ₁₉ ) + 1.0 M LIX 54 pH D _ni D _ca D _Mg β _{Ni / Ca} β _{Ni / Mg} 5.9 twenty 0.1 - 200 - 6.2 45 0.12 0.01 376 4500 6.4 132 0.13 - 1015 -

As can be seen from table 3, when using a mixture of LIX 54 + VIK fractions C ₁₁ -C ₁₉ , as in the case of using a mixture of LIX 54 + VIK fractions C ₅ -C ₉ (table 1), high nickel distribution coefficients and coefficients are realized the separation of Nickel and alkaline earth elements, which are much higher than in the known method (prototype) (see table 2).

Example 3

This example shows the effect of the composition of the extractant on the separation of nickel with calcium and magnesium.

Table 4 shows the data on the extraction of nickel, as well as the main impurities (Ca and Mg), depending on the composition of the extractant (VIC + LIX 54) at a constant final (equilibrium) pH value (pH 6.25-6.3). The compositions of the extractants, as well as the experimental conditions are given in table.4.

Table 4
Dependence of metal extraction on the composition of the extraction mixture in kerosene
Extractant: VIC (fraction C ₅ -C ₉ ) + LIX 54 in kerosene
The initial aqueous solution, g / l: Ni - 4.75; Ca - 0.5; Mg 7.12; pH _(ref) = 6.1
Extraction conditions: Т = 22 ° С, τ = 1 h, О: В = 1: 1; pH _(con) = 6.25-6.3 No. The composition of the extractant, M D _ni D _ca D _Mg β _{Ni / Ca} β _{Ni / Mg} one 1.0 M VIC + 1.0 M LIX 54 88.0 0.13 0.02 640 4400 2 1.0 M VIC + 0.5 M LIX 54 36.5 0.1 0.008 365 4562 3 1.0 M VIC + 0.25 M LIX 54 7.0 0.16 - 44 - four* 0.5 M VIC + 1.0 M LIX 54 14.1 0.04 - 350 - 4 * - precipitation occurred during extraction.

From table 4 it is seen that with a constant content of VIC in the organic phase with a decrease in the concentration of LIX, the distribution coefficients of nickel noticeably fall and the separation of nickel and calcium worsens (No. 1-3). With a constant content of LIX and a decrease in the concentration of VIC, there is also a deterioration in nickel extraction and a decrease in the separation coefficients of nickel with calcium (No. 1, 4). In addition, with VIC deficiency, precipitation was observed during extraction (No. 4).

It is optimal to use the mixture with a molar ratio of VIC: LIX54 = 1: 1 ÷ 1: 0.5. With these ratios, high nickel distribution coefficients and nickel and calcium separation coefficients are realized. The separation coefficients of nickel and magnesium were high in all cases. From table 4 it is seen that in the proposed method, the extraction of Nickel and the degree of its separation from impurities is much higher than in the known method (prototype) (see table 2).

Example 4

Using the method of variable ratios of the aqueous and organic phases (O: B), the isotherm of nickel extraction from sulfate solutions was removed with a mixture of VIC (fraction C ₅ -C ₉ , HR) and LIX 54 in kerosene. The constancy of pH was maintained by the ammonium form of the extractant (NH ₄ R). Why it was pretreated with ammonium hydroxide. The composition of the extractant and the initial aqueous solution, as well as the experimental conditions are given in table.5.

This course of the isotherm makes it possible to extract nickel from the initial solution at O: B = 1: 2–2.5 in 2-3 stages of extraction (almost 99.75–99.85%).

Table 5
Isotherm for the extraction of nickel from a sulfate solution with a mixture of VIC and LIX 54 in kerosene
Extractant: 1.0 M VIC (0.7 M HR + 0.3 M NH ₄ R) + 0.5 M LIX 54
The initial aqueous solution, g / l: Ni - 4.82; Ca - 0.52; Mg 7.32; pH _(ref) = 6.09
Extraction conditions: Т = 22 ° С, τ = 1 h No. one 2 3 four 5 About: In 5: 1 2.5: 1 1: 1 1: 2.5 1: 5 pH _(raff) 7.0 6.9 6.3 6.1 6.0 With _{Ni (c)} , g / l 0.01 0.02 0.17 1.22 3.02 C _{Ni (o)} , g / l 1,0 1.93 4.7 9.0 9.0

Example 5

In the conditions of example 4 (table 5, No. 4) a mixture of VIC and LIX 54 in kerosene obtained an extract containing Nickel, as well as impurities of alkaline earth elements. To wash the extract from impurities (Ca and Mg), it was treated with dilute solutions of sulfuric acid at various ratios of organic and aqueous phases (O: B). The compositions of the extractant, extract, experimental conditions and the results are shown in table.6. For comparison, the data on washing the nickel extract from impurities with VIC in kerosene without LIX 54 (prototype method) are also given there.

As can be seen from the table, the effectiveness of washing the extract from calcium in the proposed method (No. 1-3) in all cases is higher than in the known method (prototype). To reduce the volume of the wash solution in the known method (O: B = 10 ÷ 15: 1) is not possible due to the relatively high distribution coefficients of calcium (D _Ca = 0.14-0.15). In addition, with a small flow of washing solution, precipitation of calcium sulfate (gypsum) is possible.

Table 6
Distribution of nickel and impurities when washing nickel extracts with sulfuric acid solutions
Wash Solution: H ₂ SO ₄ (1.5-7.5 g / L)
Extract washing conditions: Т = 22 ° С, τ = 1 h
I. The proposed method
Extractant: 1.0 M VIC (0.7 MHR + 0.3 M NH ₄ R) + 0.5 M LIX 54 in kerosene
The composition of the extract, g / l: 9.0 Ni; 0.02 Ca; 0.03 Mg No. About: In pH Ca content, g / l The degree of washing Ca, ε,% the content of Ni, g / l The degree of washing Ni, ε,% aqu.f org.f aqu.f org.f one 15: 1 6.0 0.18 0.008 60.0 0.52 8.96 0.38 2 10: 1 6.0 0.14 0.006 70.1 0.52 8.95 0.56 3 5: 1 6.1 0.08 0.004 80.0 0.51 8.89 1.20 II. The known method (prototype)
Extractant: 1.0 M VIC (0.7 MHR + 0.3 M NH ₄ R) in kerosene
The composition of the extract, g / l: 9.02 Ni; 0.08 Ca; 0.08 Mg No. About: In pH content
Ca, g / l Power
washing Ca, ε,% Ni content
g / l The degree of washing Ni, ε,% aqu.f org.f aqu.f org.f 6.1 four 5: 1 6.2 0.23 0,034 57.5 2.72 8.45

The washing of the extract from magnesium is quite effective both in the proposed method and in the prototype — the degree of washing from magnesium in all cases was> 94.5%.

As for the leaching of Nickel from the extract, then, as can be seen from the table, in the proposed method, the degree of washing of the extract from Nickel is much less than in the known (prototype), and is 0.38-1.2% and 6.1%, respectively. The increased nickel content in the wash solution (prototype) leads to an increase in the flow of extractant, since the wash solution, as a rule, combines with the original.

Obviously, in the proposed method for 2-3 stages of washing, you can almost completely clean the extract from Ca and Mg.

Example 6

Nickel was extracted from a solution of nickel sulfate (1.0 M NiSO ₄ ) with a solution of 1.0 M VIC (0.7 MHR + 0.3 M NH ₄ R) + 0.5 M LIX 54 in kerosene.

Extraction conditions: VIC fractions C ₅ -C ₉ ; O: B = 1: 1; T = 22 ° C; τ = 1 h

9.04 g / L of nickel was found in the saturated extract. Re-extraction of Nickel was carried out with a solution of sulfuric acid at various ratios of organic and aqueous phases (O: B). The composition of the extract, the experimental conditions and the results are shown in table.7.

Table 7
Reextraction of Nickel with Sulfuric Acid
Nickel content in the extract: 9.04 g / l
Stripping agent: 1.5 M (147 g / l) H ₂ SO ₄ solution
Reextraction conditions: Т = 22 ° С, τ = 1 h About: In pH (con) nickel content, g / l degree of back extraction,% No. water phase organ phase 10: 1 2.95 89.5 0.01 99.89 one 7.5: 1 <0,0 67.35 0.006 99.93 2 5: 1 <0,0 45.15 0.005 99.94 3

As can be seen from the table, almost complete nickel reextraction is already achieved in the 1st step at pH _(con) <3.0 (No. 1). In this case, there is a significant concentration of nickel in the strips.

The proposed method is quite simple, for a small number of extraction steps it is possible to obtain high-purity nickel solutions, nickel recovery is not less than 99.75%. One of the advantages of the proposed method is the use of extractants (monocarboxylic acids and LIX 54), the production of which is established on an industrial scale.

Claims (1)

The method of extracting nickel from sulfate solutions with a high content of calcium and magnesium, including the extraction of nickel at pH 6.1-6.5 with higher isocarboxylic acids (VIC) in a diluent, washing the extract from impurities and re-extraction of nickel with sulfuric acid solutions, characterized in that the extraction lead in the presence of β-diketone (1-phenyl-1,3-decanedione) (LIX 54) with a molar ratio of VIC: LIX54 = 1: 1-0.5