CN116606978A - A kind of purification method of high-concentration iron ion in hydrochloric acid solution - Google Patents

Abstract

The invention relates to a method for purifying high-concentration iron ions in a hydrochloric acid solution. The method comprises the following steps: performing multi-stage extraction on the hydrochloric acid solution containing high-concentration iron ions with an extractant, and the extractant is a mixture containing trioctyl phosphate; The pickling agent is used to remove impurities in the iron-rich organic phase to obtain an acid-washed organic phase; the pickled iron-rich organic phase is subjected to multi-stage stripping; and the solution after the multi-stage stripping is regenerated. The method adopts a new extraction system (mixture containing trioctyl phosphate phase), reduces the acidity or chloride ion concentration required for extraction, satisfies the extraction process of hydrochloric acid solution with high concentration of iron, and makes the back extraction of iron in the loaded organic The process is easy to carry out, the stripping solution does not introduce new impurities, realizes the selective extraction of iron ions, and reduces the cost of purification, extraction or concentration of iron hydrochloric acid solution.

Description

A kind of purification method of high-concentration iron ion in hydrochloric acid solution

technical field

The invention belongs to the technical field of iron ion extraction, in particular to a method for purifying high-concentration iron ions in hydrochloric acid solution.

Background technique

In the prior art, common methods for iron recovery in hydrochloric acid solution include precipitation and extraction. Precipitation methods include jarosite method, goethite method and hematite method. It is usually required to be carried out under the condition of low acidity; in addition, there are more impurities, and the purity of the iron precipitation product is low. The recovery of iron by extraction method has the advantages of high selectivity, low energy consumption and less pollution. The commonly used extraction agent for Fe ³⁺ recovery in hydrochloric acid solution is N235. The operating conditions generally require the concentration of chloride ions in the aqueous phase to be greater than 2mol/L, and the concentration of Fe ³⁺ ≤ 30g/L. In order to improve the extraction performance, N235 is usually required before extraction. Organic systems are acidified. Generally, dilute hydrochloric acid or pure water is used for stripping, but it is usually difficult to achieve 100% stripping. When Zhang Yinsheng et al. used N235 to extract iron in 11.15g/L low-concentration iron solution, 0.43mol/L hydrochloric acid was back-extracted to load organics, and the iron-extraction rate was only 74%, and multi-stage back-extraction was also difficult. Ming Liu et al. clearly pointed out in their research that iron stripping is difficult in the N235 iron-loaded organic phase. TBP (tributyl phosphate) has a positive synergistic effect on the extraction of iron from N235, and the addition of TBP can inhibit the stratification of the iron-loaded organic phase and improve the stripping efficiency of iron. However, this system only works well under the sulfuric acid system, and the iron content in the loaded organic is only 12.73g/L. In order to achieve a better stripping of iron (close to 99%), it still needs to go through three stages of cross-flow stripping. The final experimental conclusion is that the iron in the N235-TBP cooperative extraction system is still difficult to strip. Jiang Pingguo et al. used N235 to extract and recover lower concentration iron from the red mud leach solution. When stripping iron, the stripping rate of 75% was also low.

Organic TBP can be used to recover iron in hydrochloric acid solution, and stripping is relatively easy, but TBP extraction and purification of iron in hydrochloric acid solution needs to be carried out at a higher concentration of hydrochloric acid or chloride ions, which increases the purification cost or produces a large amount of NaCl waste salt. N235 is only suitable for low-concentration iron ion solution in hydrochloric acid solution. Aiming at the problem of difficult stripping of iron in N235, some studies have pointed out that using diammonium hydrogen phosphate can obtain better stripping effect. The use of diammonium hydrogen phosphate not only increases the purification cost, but also easily introduces new impurities such as P into iron products. In addition, phosphorus-containing wastewater will be produced, which will affect the ecological environment. N ₅ O ₃ extractant has better extraction effect on low concentration iron in hydrochloric acid solution. The purity of N ₅ O ₃ sold in the market is relatively low, and the active ingredients are generally about 80%. However, when the concentration of iron ions is high (>30g/L), the extraction is prone to emulsification, and there is also the problem of difficult back-extraction. Xu Wenjie and others suggested using a certain concentration of oxalic acid solution to strip iron in N ₅ O ₃ . The oxalic acid stripping agent increases the cost of iron concentration to a certain extent. In addition, oxalic acid wastewater may be generated, and the carbon content in the iron concentration product may exceed the standard.

The main disadvantages of existing iron recovery technology in hydrochloric acid: (1) the existing method is only applicable to hydrochloric acid solution with lower concentration of iron (iron ion concentration≤30g/L), and is not suitable for hydrochloric acid solution with high concentration of iron. (2) The organic back-extraction after loading iron is extremely difficult. Generally, after multiple cross-flow (>3 times) back-extraction, there are still many iron ions in the organic which are difficult to back-extract. (3) Organic extraction of iron generally needs to be carried out under relatively high hydrochloric acid or chloride ion (chloride ion concentration ≥ 4mol/L). (4) In order to improve the iron stripping effect in N235 or _N5O3 organics, oxalic acid, diammonium hydrogen phosphate and other _chemicals are used during stripping, which will increase the cost of iron ion purification and produce other difficult-to-treat wastewater. (5) The selectivity of the existing extraction system is poor, and the extraction of impurity ions such as Al, Si, Mg, and Ca is serious, which affects the purity of the final product.

Contents of the invention

For the problems referred to above, the present invention will propose a kind of purification method of high-concentration ferric ion in hydrochloric acid solution.

The technical scheme that the present invention adopts is as follows:

A method for purifying high-concentration iron ions in hydrochloric acid solution, said method comprising the steps of:

The hydrochloric acid solution containing a high concentration of iron ions is subjected to multi-stage extraction with an extractant, and the extractant is a mixture containing trioctyl phosphate;

Remove impurities in the iron-rich organic phase with a pickling agent to obtain an acid-washed organic phase;

Carry out multi-stage stripping to the iron-rich organic phase after pickling;

The solution after multistage stripping is regenerated.

Further, the mixture of trioctyl phosphate includes tributyl phosphate, dimethyl heptyl methyl phosphate, trialkyl phosphorus oxide, N,N-dimethylheptyl acetamide, isodecyl alcohol, n-octanol, One or two of isooctyl alcohol, n-butanol or 2-butanol.

Further, the three substances in the extractant are denoted as A, B, and C respectively, A represents trioctyl phosphate, B represents tributyl phosphate, dimethyl heptyl methyl phosphate, trialkylphosphine oxide, N,N- Any substance in dimethylheptylacetamide; C represents any substance in isodecyl alcohol, n-octanol, isooctyl alcohol, n-butanol, and 2-butanol; the volume ratio of A, B, and C is 0 ~90:0~90:0~20.

Further, the volume ratio of A, B, and C is 20-60:20-60:0-10.

Further, the extraction conditions are: the single-stage extraction time is 2-20 minutes; the extraction temperature is 10-80°C; the flow ratio of the organic phase to the aqueous phase is 3:1-1:10;

Pickling conditions are: single-stage washing time 2-20min; washing temperature 10-80°C; flow ratio of organic phase to aqueous phase 1:1-10:1;

The stripping conditions are: the single-stage stripping time is 2-20 minutes; the stripping temperature is 10-80°C; the flow ratio of the organic phase and the aqueous phase is 1:1-10:1;

The regeneration conditions are: regeneration time 2-20min; regeneration temperature 10-80°C; flow ratio of organic phase to water phase 1:1-10:1.

Further, the extraction temperature is 20-40°C; the back-extraction temperature is 20-40°C; and the regeneration temperature is 20-40°C.

Further, the number of extraction stages is 2-20 stages; the number of stripping stages is 1-20 stages; and the number of regeneration stages is 1-2 stages.

Further, the number of extraction stages is 3-10 stages; the number of back-extraction stages is 2-10 stages.

Further, the iron ion concentration in the hydrochloric acid solution is 0-120 g/L; the hydrochloric acid or chloride ion concentration is 0.2-12 mol/L.

Further, during the extraction process, the aqueous phase is a hydrochloric acid solution containing a high concentration of iron ions, and the concentration of the hydrochloric acid solution or chloride ions is 0.5-4mol/L; during the pickling process, the pickling agent is hydrochloric acid with a concentration of 0.2-4mol/L; The intermediate stripping agent is pure water or low-concentration hydrochloric acid solution, and the concentration of hydrochloric acid is not more than 0.01mol/L; during the regeneration process, the regeneration agent is one or two of hydrochloric acid, sodium chloride, potassium chloride, and calcium chloride. The agent concentration is 0.01～10mol/L.

The method adopts a new extraction system (mixture containing trioctyl phosphate phase), reduces the acidity or chloride ion concentration required for extraction, satisfies the extraction process of hydrochloric acid solution with high concentration of iron, and makes the back extraction of iron in the loaded organic The process is easy to carry out, the stripping solution does not introduce new impurities, realizes the selective extraction of iron ions, and reduces the cost of purification, extraction or concentration of iron hydrochloric acid solution. At the same time, the cost of trioctyl phosphate in the extraction system is lower than that of dimethyl heptyl methyl phosphate and trialkylphosphine oxide, and it is easy to popularize engineering applications.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the written description and claims hereof.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. the embodiment. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The high-concentration iron ion hydrochloric acid solution (the concentration of hydrochloric acid solution is 2mol/L) used in the embodiment of the present invention is selected from a certain iron ore, and the specific composition analysis results are shown in Table 1, which contains Al, SiO ₂ , Ca, Mg, Na, K, Cu, Ni and other impurities. Feed liquid iron ion concentration has been as high as 103.9g/L. Firstly, the test feed liquid is filtered to remove fine solid particles in the feed liquid, and then the purification test is carried out.

Table 1 Analysis of the chemical composition of an iron ore hydrochloric acid leaching solution

Example 1

The hydrochloric acid solution containing the above-mentioned high-concentration iron ion (103.9g/L) was subjected to 4-stage extraction, and the extractant was 45% trioctyl phosphate, 45% tributyl phosphate and 10% n-octanol (both in volume concentration); The single-stage extraction time is 5 minutes, and the extraction temperature is 30°C; the O/A ratio of the organic phase and the aqueous phase during the extraction process is 2:1. For washing, 2mol/L hydrochloric acid solution was used for four-stage washing, and the O/A ratio was 4:1. After loading the organic phase, it goes through 4 stages of back extraction, and the back extraction is carried out with 0.01mol/L hydrochloric acid. During the back extraction process, the O/A ratio of the organic phase and the aqueous phase is 2:1; °C, the iron stripping rate is 100%. The regeneration of organic washing is carried out by 5g/L NaCl solution, the O/A ratio is 4:1, and 3-stage countercurrent washing.

Example 2

The hydrochloric acid solution (same as Example 1) containing the above-mentioned high-concentration iron ions is carried out to 6 stages of extraction, and the extractant is 60% trioctyl phosphate and 40% tributyl phosphate (both in volume concentration); single-stage extraction time 5min, The extraction temperature is 30°C, and the O/A ratio of the organic phase to the aqueous phase during the extraction process is 2:1; the extraction rate of iron ions in the 6-stage extraction solution is 100%, and the extraction rate of other metal impurity ions and silicon ions is 0. After four stages of back extraction, the back extraction is carried out with pure water, the single-stage back extraction time is 5min, the back extraction temperature is 70°C, the O/A ratio of the organic phase and the water phase is 1.5:1 during the back extraction process, and the iron back extraction Rate 100%. The extraction and stripping effects are good.

Example 3

The hydrochloric acid solution (with embodiment 1) containing above-mentioned high-concentration iron ion is carried out 6 grades of extractions, and extraction agent is 50% trioctyl phosphate and 50% dimethyl heptyl methyl phosphate (both volume concentration); Single-stage extraction The time is 5 minutes, the extraction temperature is 30°C, and the extraction conditions are: O/A ratio is 2:1; after 6 stages of countercurrent extraction, the extraction rate of iron ions in the solution is 100%. Afterwards, 4 stages of back extraction were performed, and the back extraction was carried out with pure water, the back extraction temperature was 50°C, the total back extraction time was 20 min, and the O/A ratio of the organic phase and the aqueous phase during the back extraction process was 1.8:1. After 4 stages of countercurrent stripping, the iron stripping rate is 100%. The extraction and stripping effects are good.

Example 4

Adopt iron ore hydrochloric acid leaching solution 2mol/L hydrochloric acid solution (same as embodiment 1) to dilute 1 times and carry out 4 grades of extractions, extraction agent is 50% trioctyl phosphate, 40% N ₅ 0 ₃ and 10% isooctyl alcohol (both by volume concentration). Extraction conditions The O/A ratio is 2:1, the single-stage extraction time is 5min, and the extraction temperature is 30°C. After 4 stages of countercurrent extraction, the extraction rate of iron ions is 100%. After that, five stages of back extraction were performed, using pure water for back extraction, the back extraction temperature was 40°C, the total back extraction time was 30 minutes, and the O/A ratio of the organic phase and the water phase during the back extraction process was 2:1. The iron stripping rate is 100% after the 5-stage countercurrent stripping.

Example 5

The hydrochloric acid solution (with embodiment 1) containing above-mentioned high-concentration iron ion is carried out 6 grades of extractions, and extraction agent is 45% trialkyl phosphorus oxide, 45% dimethyl heptyl methyl phosphate and 10% isodecyl alcohol (both are volume concentration). Extraction conditions The O/A ratio is 2:1, the single-stage extraction time is 4min, and the extraction temperature is 40°C. After 6 stages of countercurrent extraction, the extraction rate of iron ions in the solution is 100%. After four stages of back extraction, the back extraction is carried out with 0.005mol/L hydrochloric acid solution, the back extraction temperature is 50°C, the total back extraction time is 24min, and the O/A ratio of the organic phase and the aqueous phase during the back extraction process is 1.8:1. After 4 stages of countercurrent stripping, the iron stripping rate is 99.1%. The extraction and stripping effects are good.

Comparative example 1

Use iron ore hydrochloric acid leaching solution 2mol/L hydrochloric acid solution (same as Example 1) to dilute 1 times to carry out 4-stage extraction, extractant is 30% N,N-dimethylheptyl acetamide (N ₅ O ₃ ) and 70% sulfonated Kerosene (all volume concentrations). Extraction conditions The O/A ratio is 2:1, the single-stage extraction time is 10min, the extraction temperature is 30°C, and the extraction rate of iron ions is 95%. After that, 3 stages of stripping were carried out. Pure water stripping was used for the stripping. The stripping temperature was 40°C. The total stripping time was 20 minutes. The O/A ratio of the organic phase and the aqueous phase was 1.5:1 during the stripping process. After three-stage cross-flow stripping, the N ₅ O ₃ organic system is still dark yellow, and the organic still contains a relatively high concentration of iron ions. The iron stripping rate is 80%, and the stripping effect is poor.

Comparative example 2

The hydrochloric acid solution (with embodiment 1) containing above-mentioned high-concentration ferric ion is carried out 6 grades of extractions, and extraction agent is 40% tributyl phosphate and 60% sulfonated kerosene (both volume concentration), adopts hydrochloric acid to adjust aqueous phase chloride ion Concentration, so that the concentration of chloride ions is 5mol/L. Extraction conditions The O/A ratio is 3:1, the single-stage extraction time is 10min, and the extraction temperature is 30°C. After 6 stages of countercurrent extraction, the extraction rate of iron ions in the solution is 82%. After 6 stages of back extraction, the back extraction is carried out with pure water, the back extraction temperature is 45°C, the back extraction time is 30min, and the O/A ratio of the organic phase and the water phase during the back extraction process is 2:1. After 6 stages of countercurrent stripping, the iron stripping rate is 100%. Back extraction works better, but extraction requires higher acidity or chloride ion concentration.

Analysis of the results of the above examples shows that compared with the existing extraction system (comparative example 1), iron is more difficult to back-extract after extraction; the use of trioctyl phosphate in the extraction system of Examples 1-4 can greatly improve the organic Medium iron stripping efficiency, especially the extraction of iron in high ferric hydrochloric acid solution.

In the extraction system of Examples 1-4, trioctyl phosphate was added, compared with the extraction system (a mixture of tributyl phosphate and sulfonated kerosene) in Comparative Example 2, it can significantly improve the extraction rate of iron ions. Post-iron can be stripped more easily. However, when tributyl phosphate is used in the extraction system, its ability to extract iron is limited. In order to improve the ability of tributyl phosphate to extract iron ions, the extraction needs to be carried out under a higher concentration of hydrochloric acid. Substituting trioctyl phosphate for part of tributyl phosphate can reduce the higher hydrochloric acid concentration required when only tributyl phosphate is used to extract iron, and at the same time improve the iron extraction capacity of the extraction system.

Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that: they can still modify the technical solutions described in the aforementioned embodiments, or perform equivalent replacements for some of the technical features; and these The modification or replacement does not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (10)

1. a method for purification of high-concentration iron ion in hydrochloric acid solution, described method comprises the steps: The hydrochloric acid solution containing a high concentration of iron ions is subjected to multi-stage extraction with an extractant, and the extractant is a mixture containing trioctyl phosphate; Remove impurities in the iron-rich organic phase with a pickling agent to obtain an acid-washed organic phase; Carry out multi-stage stripping to the iron-rich organic phase after pickling; The solution after multistage stripping is regenerated. 2. The method according to claim 1, wherein the mixture of said trioctyl phosphate comprises tributyl phosphate, dimethyl heptyl methyl phosphate, trialkyl phosphorus oxide, N,N-dimethylheptyl ethyl One or both of amides, isodecyl alcohol, n-octanol, isooctyl alcohol, n-butanol or 2-butanol. 3. method according to claim 2, wherein, in extractant, three kinds of materials are respectively marked as A, B, C, and A represents trioctyl phosphate, and B represents tributyl phosphate, methyl heptyl phosphate, Any of trialkylphosphine oxide, N,N-dimethylheptylacetamide; C represents any of isodecyl alcohol, n-octanol, isooctyl alcohol, n-butanol, and 2-butanol; The volume ratio of A, B, and C is 0-90:0-90:0-20. 4. The method according to claim 3, wherein the volume ratio of A, B, and C is 20-60:20-60:0-10. 5. The method according to claim 1, wherein the extraction conditions are: the single-stage extraction time is 2 to 20 minutes; the extraction temperature is 10 to 80°C; the flow ratio of the organic phase to the aqueous phase is 3:1 to 1:10 _; Pickling conditions are: single-stage washing time 2-20min; washing temperature 10-80°C; flow ratio of organic phase to aqueous phase 1:1-10:1; The stripping conditions are: the single-stage stripping time is 2-20 minutes; the stripping temperature is 10-80°C; the flow ratio of the organic phase and the aqueous phase is 1:1-10:1; The regeneration conditions are: regeneration time 2-20min; regeneration temperature 10-80°C; flow ratio of organic phase to water phase 1:1-10:1. 6. The method according to claim 5, wherein the extraction temperature is 20-40°C; the back-extraction temperature is 20-40°C; and the regeneration temperature is 20-40°C. 7. The method according to claim 1, wherein, the extraction stages are 2-20 stages; the stripping stages are 1-20 stages; and the regeneration stages are 1-2 stages. 8. The method according to claim 7, wherein the extraction stages are 3 to 10 stages; the stripping stages are 2 to 10 stages. 9. The method according to any one of claims 1-8, wherein the concentration of iron ions in the hydrochloric acid solution is 0-120 g/L; the concentration of hydrochloric acid or chloride ions is 0.2-12 mol/L. 10. The method according to claim 9, wherein, in the extraction process, the aqueous phase is a hydrochloric acid solution containing high-concentration iron ions, and the hydrochloric acid solution or chloride ion concentration is 0.5～4mol/L; 0.2～4mol/L hydrochloric acid; during the stripping process, the stripping agent is pure water or low-concentration hydrochloric acid solution, and the concentration of hydrochloric acid is not more than 0.01mol/L; during the regeneration process, the regeneration agent is hydrochloric acid, sodium chloride, potassium chloride, chloride One or two kinds of calcium, the regenerant concentration is 0.01-10mol/L.