RU2796484C1 - Method for extraction of iron(iii) chloride from a chloride solution - Google Patents

Abstract

FIELD: hydrometallurgy.

SUBSTANCE: chloride solution containing iron(II) chloride and impurity elements is taken. It is oxidized with air oxygen, taken in excess with respect to iron (II), at a temperature of 50-80°C for 0.6-6.0 h in the presence of an extractant with a flash point of at least 81°C, taken in excess with respect to the total amount of iron, at a ratio of organic and aqueous phases in the resulting mixture, equal to (1-5):1. Tributyl phosphate is used as an extractant in form of a solution in an inert diluent; or alcohol (octanol-1, decanol-1 or dodecanol-1); or a ketone, such as undecanone-2; or a mixture of said alcohol and ketone. The resulting iron(III) chloride, transferred into the organic phase, is subjected to multistage re-extraction to obtain a solution of iron(III) chloride. Before re-extraction of iron(III) chloride, the extract can be washed with hydrochloric acid or a solution of iron(III) chloride.

EFFECT: invention makes it possible to increase the ease of the process due to the use of extractants with a high flash point and low solubility in an aqueous solution, as well as the degree of extraction of iron(III) chloride from a chloride solution by 10-56%.

6 cl, 7 ex

Description

The invention relates to hydrometallurgy and can be used to extract iron(III) from chloride solutions containing iron(II) and impurity elements.

When processing polymetallic raw materials using hydrochloride technology, solutions are obtained that usually contain iron (II). As is known, iron(II) is practically not extracted from chloride solutions by sorption and extraction methods, which requires its preliminary oxidation to iron(III) using various oxidizers. When oxygen or an oxygen-containing gas mixture is used for oxidation at atmospheric pressure, the process is extremely slow, which makes the method for extracting iron(III) chloride ineffective. To increase the rate of iron(II) chloride oxidation, hydrogen peroxide or chlorine and its derivatives are used as oxidizing agents.

A known method for extracting iron(III) chloride from a chloride solution containing iron(II) (see Pat. 1947122 B2 DE, IPC ⁷ C01G 23/00, 49/00, C22B 3/26, 1973), according to which ilmenite is leached to obtain an iron(II) chloride solution containing titanium and other impurity elements. To extract iron from solution, iron(II) is converted into iron(III) using chlorine as an oxidizing agent. The iron(III) is then recovered by extraction using methyl isobutyl ketone, which has a low flash point (14° C.) and a very high (17 g/l) solubility in water.

The disadvantage of this method is the use of aggressive chlorine for the oxidation of iron(II), and for the extraction of iron(III) - an extractant having a high solubility and a low flash point, which makes the method flammable and explosive.

There is also a method for extracting iron(III) chloride from a chloride solution (see US Pat. ) use a mixture of high molecular weight aliphatic alcohols and ketones having low solubility and a flash point above 61°C. When iron(II) is present in the initial chloride solution, before extraction, the solution is treated with an oxidizing agent, which is gaseous chlorine or sodium hypochlorite.

The use of chlorine-containing oxidizing agents reduces the safety of the method, and in the case of sodium hypochlorite, the chloride solution is contaminated with sodium ions.

Also known, taken as a prototype, is a method for extracting iron(III) chloride from a chloride solution (see application 102660678A CN, IPC C22B 3/00, 3/26 (2006.01), 2012), according to which a chloride solution containing iron chloride ( II), and the extractant is stirred. As an extractant, a ketone, an alcohol, an oxygen- or phosphorus-containing ether, a nitrogen-substituted amide or a tertiary amine are used, which are used in a mixture with a diluent: kerosene, benzene, toluene, xylene, cyclohexane. An oxygen-containing gas is introduced into the resulting mixture with simultaneous oxidation of iron(II) chloride and extraction of iron(III) chloride at a temperature of 25-40 ° C, a molar ratio of extractant and iron equal to 2-5: 1, with an excess of injected oxygen-containing gas in 2- 10 times the theoretical required amount. The process of oxidation and extraction is carried out in one or more stages, with the duration of each stage being at least 15 minutes. After that, stirring is stopped and an oxygen-containing gas is introduced, the resulting mixture is kept for at least 3 minutes, and the chloride solution (raffinate) purified from iron(III) is separated from the iron-containing organic phase - extract. Then, a multi-stage aqueous stripping of iron(III) chloride is carried out to obtain a solution of iron(III) chloride. In a multi-stage process, the raffinate from the previous stage is the starting chloride solution for the next stage.

The disadvantage of the known method is that the used diluents and part of the extractants are flammable liquids with a flash point from -11°C to 28°C, which makes the method flammable, and when oxygen is used, explosive. The disadvantage of this method is also its low efficiency. When carrying out the method in one stage after extraction in a chloride solution - raffinate remains 43-56 g/l of iron, which corresponds to the degree of extraction of 44-57%. When carrying out the process in several stages, it is possible to increase the degree of extraction of iron(III) chloride, but even in this case, when using air for oxidation after two stages of oxidation and extraction, the residual iron concentration in the solution was 13 g/l, which corresponds to 87% iron extraction ( III). When carrying out the process in several stages, the degree of extraction of iron(III) chloride increases, but only when oxygen is used for oxidation, which reduces the safety of the method.

The present invention is aimed at achieving a technical result, which consists in increasing the degree of extraction of iron(III) chloride, as well as the manufacturability of the method through the use of extractants with a high temperature flash and low solubility in an aqueous solution.

The technical result is achieved by the fact that in the method for extracting iron (III) chloride from a chloride solution containing iron (II) chloride and impurity elements, including the oxidation of iron (II) chloride with air oxygen taken in excess with respect to iron (II), in a mixture of a chloride solution and an extractant taken in excess with respect to the total amount of iron, with the transfer of iron (III) chloride into the organic phase and its multistage re-extraction to obtain a solution of iron (III) chloride, according to the invention, oxidation with atmospheric oxygen is carried out at a temperature of 50- 80°C in the presence of an extractant with a flash point of at least 81°C for 0.6-6.0 hours, while the extractant is taken in an amount that provides the ratio of the organic and aqueous phases in the mixture, equal to 1-5:1.

The technical result is also achieved by the fact that the initial chloride solution contains an admixture of copper in an amount of at least 0.5 g/l.

The technical result is also achieved by using tributyl phosphate, alcohol, ketone or a mixture of alcohol and ketone as the extractant.

The achievement of the technical result is facilitated by the fact that octanol-1, decanol-1, dodecanol-1 are used as alcohol, and undecanone-2 is used as a ketone.

The achievement of the technical result is also facilitated by the fact that tributyl phosphate is used as a solution in a diluent.

The achievement of the technical result is also facilitated by the fact that before the re-extraction of iron(III) chloride, the extract is washed using hydrochloric acid or a solution of iron(III) chloride.

The essential features of the claimed invention, which determine the scope of legal protection and are sufficient to obtain the above technical result, perform the functions and correlate with the result as follows.

Oxidation of iron(II) chloride with atmospheric oxygen at a temperature of 50-80°C provides a high degree of oxidation and a high degree of extraction of iron(III) chloride.

At temperatures below 50°C, the degree of oxidation of iron(II) chloride decreases and, accordingly, the extraction of iron(III) chloride. At temperatures above 80°C, a high degree of oxidation and extraction of iron is achieved, but the manufacturability of the method decreases due to a decrease in its safety and an increase in the entrainment of the extractant when passing air.

The use of an extractant with a flash point of at least 81°C ensures the safety of the method by eliminating the ignition of the extractant. In addition, extractants with a high flash point are at the same time poorly soluble compounds and therefore, when used, their losses with the aqueous phase are minimal.

Oxidation of iron(II) chloride with atmospheric oxygen for 0.6-6.0 hours provides a high degree of extraction of iron(III) chloride. When oxidation is carried out for less than 0.6 hours, the extraction of iron(III) chloride decreases, and oxidation for more than 6 hours does not lead to a significant increase in the extraction of iron(III) chloride, but reduces the productivity of the method.

The use of the extractant in an amount that provides the ratio of the organic and aqueous phases in the mixture, equal to 1-5:1, increases the rate of oxidation of iron(II) chloride and provides a high degree of extraction of iron(III) chloride. An increase in the ratio of organic and aqueous phases above 5:1 does not lead to an increase in the extraction of iron(III) chloride, but reduces the manufacturability of the method, and when the ratio decreases below 1:1, the extraction of iron(III) chloride decreases.

The combination of the above features is necessary and sufficient to achieve the technical result of the invention, which consists in increasing the degree of extraction of iron(III) chloride, as well as the manufacturability of the method through the use of extractants with a high temperature flash and low solubility in an aqueous solution.

In particular cases of the invention, the following operations and operating parameters are preferable.

The content of copper impurities in the chloride solution in an amount of at least 0.5 g/l contributes to an increase in the rate of oxidation of iron(II) chloride.

The use of tributyl phosphate, alcohol, ketone or a mixture of alcohol and ketone as an extractant provides a high extraction of iron(III) chloride from the chloride solution.

The use of octanol-1, decanol-1, dodecanol-1 as an alcohol, and undecanone-2 as a ketone is due to their high flash point, which contributes to the safety of the method and an increase in the degree of extraction of iron(III) chloride. This improves the manufacturability of the method.

The use of tributyl phosphate in the form of a solution in an inert diluent improves the manufacturability of the method by reducing the density of the extractant and improving the stripping of iron(III) chloride.

The implementation before the stripping of iron(III) chloride, washing the extract with hydrochloric acid or a solution of iron(III) chloride helps to reduce the concentration of impurity elements in the extract, which increases the manufacturability of the method.

The above particular features of the invention make it possible to carry out the method in the optimal mode from the point of view of increasing the degree of extraction of iron(III) chloride, as well as improving the manufacturability of the method through the use of extractants with a high temperature flash and low solubility in an aqueous solution.

The essence of the proposed method can be illustrated by the following Examples.

Example 1. Take 1 l of the original chloride solution formed during hydrochloric acid leaching of converter slag of nickel production composition, g/l: 51.3 iron(II), 0.6 nickel, 0.2 cobalt, 2.3 magnesium, 3 .5 calcium, 310 chloride ions, including 210 g/l free hydrochloric acid. Iron(II) is oxidized with atmospheric oxygen, taken with a 5-fold excess relative to iron(II), by passing air through the mixture formed as a result of continuous mixing of the chloride solution and the extractant with a flash point of 86 ° C, containing 30% undecanone- 2, 35% octanol-1 and 35% decanol-1 at O:B=3:1 and 50°C for 5 hours.

The result is 3060 ml of an extract containing, g/l: 16.23 iron (III), 0.08 nickel, 0.05 cobalt, 0.1 magnesium, 0.14 calcium and 940 ml of raffinate containing 1.74 g /l iron(III). The degree of extraction of iron(III) chloride from the chloride solution was 96.8%.

Then, iron(III) chloride is re-extracted with hydrochloric acid at a concentration of 0.2 mol/l at a ratio of O:B=5:1 in 4 steps to obtain 610 ml of re-extract in the form of an iron(III) chloride solution containing, g/l: 83 .6 iron (III), 0.39 nickel, 0.24 cobalt, 0.48 magnesium, 0.64 calcium and 3 l of purified extractant containing 0.09 g / l iron (III), which is sent to the preparation of the reaction mixture .

Example 2. Take 1 l of the original chloride solution, which is a nickel electrolyte of the composition, g / l: 10 iron (II), 185 nickel, 4.55 cobalt, 0.5 copper, 30 sulfate ion, 285 chloride ion, in including 36 g/l free hydrochloric acid. Oxidation of iron(II) chloride is carried out with atmospheric oxygen taken with a 3-fold excess relative to iron(II) by passing air through the mixture formed as a result of continuous mixing of the chloride solution and the extractant in the form of tributyl phosphate with a flash point of 145°C , at O:B=4:1, temperature 80°C for 0.6 hours.

The result is 4080 ml of an extract containing, g/l: 2.38 iron(III), 0.57 nickel, 0.11 cobalt, 0.15 copper and 920 ml of raffinate containing 0.29 g/l iron(III ). The degree of extraction of iron(III) chloride from the chloride solution was 97.3%.

Then, iron(III) chloride is re-extracted with hydrochloric acid at a concentration of 0.5 mol/l at a ratio of O:B=8:1 in 6 steps to obtain 590 ml of re-extract in the form of an iron(III) chloride solution containing, g/l: 16 .5 iron(III), 3.94 nickel, 0.76 cobalt, 1.04 copper and 4 l of purified extractant containing 0.05 g/l iron(III), which is sent to the preparation of the reaction mixture.

Example 3. Take 1 liter of the original chloride solution according to Example 2. Iron(II) chloride is oxidized with atmospheric oxygen, taken with a 4-fold excess relative to iron(II), by passing air through the mixture formed as a result of continuous stirring of the chloride solution and extractant in the form of octanol-1 with a flash point of 81°C, at O:B=2:1, a temperature of 65°C for 4 hours.

The result is 2040 ml of an extract containing, g/l: 4.82 iron(III), 1.2 nickel, 0.09 cobalt, 0.14 copper and 950 ml of raffinate containing 0.168 g/l iron(III). The degree of extraction of iron(III) chloride from the chloride solution was 98.4%.

Then, the extract is washed from impurity elements with a solution of iron(III) chloride with an iron(III) concentration of 80 g/l in 3 steps at a ratio of O:B=5:1. The result is 2070 ml of a washed extract containing, g/l: 6.03 iron(III), 0.002 nickel, 0.001 cobalt, 0.001 copper and 410 ml of washing solution, composition, g/l: 73.9 iron(III), 6.01 nickel, 0.445 cobalt, 0.699 copper, which is added to the original chloride solution.

Iron(III) chloride is stripped with water at a ratio of O:B=10:1 in 5 stages to obtain 277 ml of a back extract in the form of an iron(III) chloride solution containing, g/l: 45.1 iron(III), 0.014 nickel, 0.007 cobalt, 0.007 copper and 2 l of purified extractant containing 0.001 g/l of iron(III), which is sent to the preparation of the reaction mixture.

Example 4. Take 1 l of the initial chloride solution, which is a nickel electrolyte composition, g / l: 9 iron (II), 193 nickel, 5 cobalt, 1.5 copper, 40 sulfate ion, 300 chloride ion, including 36 g/l free hydrochloric acid. Oxidation of iron(II) chloride is carried out with atmospheric oxygen, taken with a 6-fold excess relative to iron(II), by passing air through the mixture formed as a result of continuous mixing of the chloride solution and the extractant in the form of dodecanol-1 with a flash point of 127°C , at O:B=1:1, temperature 70°C for 6 hours.

The result is 1020 ml of an extract containing, g/l: 8.91 iron(III), 1.4 nickel, 0.3 cobalt, 0.3 copper and 980 ml of raffinate containing 0.075 g/l iron(III). The degree of extraction of iron(III) chloride from the chloride solution was 99.2%.

Re-extraction of iron(III) chloride is carried out with hydrochloric acid with a concentration of 0.2 mol/l at a ratio of O:B=5:1 in 4 stages to obtain 220 ml of re-extract in the form of a solution of iron(III) chloride, containing, g/l: 44, 54 iron(III), 6.97 nickel, 1.46 cobalt, 1.47 copper and 1 liter of purified extractant containing 0.005 g/l iron(III), which is sent to the preparation of the reaction mixture.

Example 5. Take 1 liter of the original chloride solution according to Example 4. Iron(II) chloride is oxidized with atmospheric oxygen, taken with an 8-fold excess relative to iron(II), by passing air through the mixture formed as a result of continuous stirring of the chloride solution and extractant in the form of undecanone-2 with a flash point of 89°C, at O:B=3:1 and a temperature of 80°C for 5 hours.

The result is 3010 ml of an extract containing, g/l: 4.49 iron(III), 0.09 nickel, 0.04 cobalt, 0.01 copper and 990 ml of raffinate containing 0.005 g/l iron(III). The degree of extraction of iron(III) chloride from the chloride solution was 99.8%.

Iron(III) chloride is stripped with water at a ratio of O:B=8:1 in 4 steps to obtain 250 ml of a strip in the form of a solution of iron(III) chloride containing, g/l: 35.9 iron(III), 0, 72 nickel, 0.32 cobalt, 0.08 copper and 2 l of purified extractant containing 0.003 g/l of iron(III), which is sent to the preparation of the reaction mixture.

Example 6. Take 1 liter of the stock solution according to Example 1. Iron(II) chloride is oxidized with atmospheric oxygen, taken with a 7-fold excess relative to iron(II), by passing air through the mixture formed as a result of continuous stirring of the chloride solution and extractant with a flash point of 130°C, containing 80% tributyl phosphate and 20% inert diluent RJ-3, at O:B=5:1 and a temperature of 75°C for 4 hours.

The result is 5100 ml of an extract containing, g/l: 10.05 iron(III), 0.03 nickel, 0.008 cobalt, 0.1 magnesium, 0.3 calcium and 900 ml of raffinate containing 0.007 g/l iron( III). The degree of extraction of iron(III) chloride from the chloride solution was 99.9%.

Then, the extract is washed from impurity elements with a solution of hydrochloric acid with a concentration of 8 mol/l in 3 steps at a ratio of O:B=10:1. The result is 5120 ml of washed extract containing, g/l: 10.01 iron (III), 0.003 nickel, 0.002 cobalt, 0.03 magnesium, 0.04 calcium and 490 ml of washing solution, composition, g/l: 0 ,4 iron (III), 0.03 nickel, 0.078 cobalt, 0.97 magnesium, 2.6 calcium, which is directed to the acidification of the initial chloride solution.

Re-extraction of iron(III) chloride is carried out with hydrochloric acid with a concentration of 0.5 mol/l at a ratio of O:B=5:1 at 6 steps to obtain 1140 ml of re-extract in the form of an iron(III) chloride solution containing, g/l: 45 iron (III), 0.015 nickel, 0.01 cobalt, 0.15 magnesium, 0.2 calcium and 5 l of purified extractant containing 0.5 g/l iron(III), which is sent to the preparation of the reaction mixture.

From the above Examples, it can be seen that the method according to the invention allows to increase the degree of extraction of iron(III) chloride from the chloride solution by about 10-56%. The use of extractants with low solubility in aqueous solution and a flash point of at least 81°C improves the manufacturability of the method. The method is relatively simple and can be implemented under industrial conditions.

Example 7. Take 1 l of the original chloride solution formed during hydrochloric acid leaching of converter slag of nickel production composition, g/l: 51.3 iron(II), 0.6 nickel, 0.2 cobalt, 2.3 magnesium, 3 .5 calcium, 310 chloride ions, including 210 g/l free hydrochloric acid. Oxidation of iron(II) chloride is carried out with air oxygen taken with a 5-fold excess relative to iron(II) by passing air through the mixture formed as a result of continuous mixing of the chloride solution and the extractant with a flash point of 86 ° C, containing 70% octanol -1, 30% undecanone-2, at O:B=3:1 and 55°C for 5 hours.

The result is 3060 ml of an extract containing, g/l: 16.23 iron (III), 0.08 nickel, 0.05 cobalt, 0.1 magnesium, 0.14 calcium and 940 ml of raffinate containing 1.5 g /l iron(III). The degree of extraction of iron(III) chloride from the chloride solution was 97.1%.

Then, iron(III) chloride is re-extracted with hydrochloric acid at a concentration of 0.2 mol/l at a ratio of 0:B=5:1 in 4 stages to obtain 610 ml of re-extract in the form of an iron(III) chloride solution containing, g/l: 84 .8 iron (III), 0.38 nickel, 0.23 cobalt, 0.45 magnesium, 0.6 calcium and 3 l of purified extractant containing 0.09 g / l iron (III), which is sent to the preparation of the reaction mixture .

Claims (6)

1. A method for extracting iron(III) chloride from a chloride solution containing iron(II) chloride and impurity elements, including the oxidation of iron(II) chloride with atmospheric oxygen, taken in excess with respect to iron(II), in a mixture of chloride solution and extractant , taken in excess with respect to the total amount of iron, with the transfer of iron (III) chloride into the organic phase and its multistage re-extraction to obtain a solution of iron (III) chloride, characterized in that the oxidation with atmospheric oxygen is carried out at a temperature of 50-80 ° C in the presence of an extractant with a flash point of at least 81°C for 0.6-6.0 hours, while the extractant is taken in an amount that provides the ratio of the organic and aqueous phases in the mixture, equal to 1-5:1. 2. The method according to p. 1, characterized in that the initial chloride solution contains an admixture of copper in an amount of at least 0.5 g/l. 3. The method according to p. 1, characterized in that tributyl phosphate, alcohol, ketone or a mixture of alcohol and ketone are used as the extractant. 4. The method according to p. 3, characterized in that octanol-1, decanol-1, dodecanol-1 are used as alcohol, and undecanone-2 is used as ketone. 5. The method according to p. 3, characterized in that tributyl phosphate is used as a solution in an inert diluent. 6. The method according to p. 1, characterized in that before re-extraction of iron(III) chloride, the extract is washed using hydrochloric acid or a solution of iron(III) chloride.