Solvent extraction preparation method of high-purity ferrous oxalate
By employing a solvent extraction method involving acid leaching, multi-stage extraction, washing, and back-extraction, the problem of ferrous oxalate purity being limited by raw material purity has been solved, achieving the preparation of high-purity ferrous oxalate with low pollution, low energy consumption, and low cost.
Patent Information
- Application Number
- CN202511290553.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-10
- Publication Date
- 2025-11-07
AI Technical Summary
Existing methods for preparing ferrous oxalate result in low purity, significant environmental pollution, high energy consumption, and high production costs, failing to meet the market demand for high-purity ferrous oxalate.
Iron-containing raw materials were subjected to acid leaching with an acid solution, followed by solvent extraction using a multi-stage extraction, washing, and back-extraction method to selectively extract iron. Finally, a reduction conversion treatment was performed to obtain high-purity ferrous oxalate.
The preparation of ferrous oxalate with high purity (greater than 99.99%), low pollution, low energy consumption and low production cost was achieved, with an iron yield greater than 98%.
Smart Images
Figure CN120904039A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of ferrous oxalate preparation, and particularly relates to a solvent extraction preparation method of high-purity ferrous oxalate. BACKGROUND
[0002] Ferrous oxalate is widely used in the production of colorants for dyes, paints, ceramics, glassware and the like, and new type of photosensitive materials, and is also a main raw material required for synthesizing nano magnetic materials, porous materials of super capacitors and lithium ion battery lithium iron phosphate positive electrode materials. The crystal form, hydrated ion composition and purity of ferrous oxalate have a great influence on the performance of synthesized lithium iron phosphate.
[0003] The existing preparation methods of ferrous oxalate can be roughly divided into several categories. Specifically as follows:
[0004] (1) Using various industrial iron-containing waste residues as raw materials to prepare ferrous oxalate through leaching, precipitation and the like, for example: using at least one of red soil nickel ore leaching residue, roasting cyanide tailings, high-phosphorus hematite, sulfuric acid residue and bayer red mud as raw materials, using sulfuric acid or hydrochloric acid as an in-out medium, adding oxalic acid or oxalate, and obtaining ferrous oxalate under certain pH and temperature conditions; adopting a low-concentration hydrochloric acid-oxalic acid two-stage acid leaching red mud process, leaching impurities with a low-concentration hydrochloric acid solution, and obtaining ferrous oxalate by adding ascorbic acid after oxalic acid leaching to obtain high-iron oxalate.
[0005] (2) Using iron-containing minerals as raw materials to produce ferrous oxalate, for example: using siderite as raw material to prepare ferrous oxalate through inorganic acid leaching, oxidation and reduction processes; using hematite as raw material to prepare ferrous oxalate through oxalic acid hot leaching and photocatalytic conversion.
[0006] (3) Preparation methods of ferrous oxalate with different morphologies, for example: using ferrous salt as raw material, adding a composite surfactant, and controlling the crystal nucleation and growth process to obtain ferrous oxalate nanowires; spraying the ferrous sulfate solution into the oxalic acid solution through a high-speed centrifugal atomizer, and forming a ferrous oxalate suspension under the cavitation effect of ultrasonic waves.
[0007] (4) Preparation methods of ferrous oxalate with different crystal forms, for example: mixing ferrous salt, water and N-methyl pyrrolidone to obtain a ferrous salt suspension, then mixing oxalic acid and N-methyl pyrrolidone to obtain an oxalic acid solution, and finally mixing the ferrous salt suspension and the oxalic acid solution to perform a precipitation reaction, thereby obtaining alpha-ferrous oxalate.
[0008] In summary, the purity of the iron source determines the purity of ferrous oxalate, but the current preparation method only involves raw material purification, and lacks the purification process of the iron source or iron-containing compounds. Moreover, with the rapid development of high-pressure dense lithium iron phosphate with high energy density and superior fast-charging performance, the existing preparation method of ferrous oxalate has low purity, high environmental pollution, high energy consumption, and high production cost, which cannot meet the market demand for the production of high-purity ferrous oxalate.
[0009] Therefore, there is an urgent need for a solvent extraction preparation method of high-purity ferrous oxalate to meet the market demand for the production of high-purity ferrous oxalate. SUMMARY
[0010] The purpose of the present application is to provide a solvent extraction preparation method of high-purity ferrous oxalate, which solves the problem that the purity of ferrous oxalate is limited by the purity of raw materials, and realizes the preparation of high-purity ferrous oxalate with low pollution, low energy consumption and low production cost.
[0011] To achieve the above purpose, the present application provides a solvent extraction preparation method of high-purity ferrous oxalate, comprising the following steps:
[0012] S1, using an acid solution to perform acid leaching treatment on an iron-containing raw material, and filtering to obtain an iron-containing leaching solution;
[0013] S2, using an organic phase containing an extractant to perform multi-stage extraction on the iron-containing leaching solution, selectively extracting iron, and obtaining an iron-loaded organic phase;
[0014] S3, using a detergent to wash the iron-loaded organic phase, and obtaining a purified organic phase;
[0015] S4, using an oxalic acid-based stripping agent to perform stripping extraction on the purified organic phase, and obtaining an iron oxalate stripping solution;
[0016] S5, performing reduction conversion treatment on the iron oxalate stripping solution, and obtaining high-purity ferrous oxalate.
[0017] Preferably, the acid solution in S1 is at least one of sulfuric acid solution, hydrochloric acid solution and hydrofluoric acid.
[0018] Preferably, the iron-containing raw material in S1 is at least one of iron minerals, industrial iron-containing waste slag, pickling waste liquid, red mud leaching solution and ilmenite leaching solution.
[0019] Preferably, the extractant in S2 comprises: an acidic extractant, a neutral extractant and a basic extractant; the acidic extractant comprises: a sulfonic acid extractant, a carboxylic acid extractant and an acidic phosphorus-containing extractant; the neutral extractant comprises: a neutral phosphorus-containing extractant, an alcohol extractant, a ketone extractant and a sulfoxide extractant; the basic extractant is an amine extractant, comprising: a hydrophobic primary amine, a secondary amine and a quaternary amine salt; the amine extractant has a carbon atom number of 6-30 and a nitrogen atom number of 1-3.
[0020] Preferably, the iron ion concentration in the iron-loaded organic phase is 0.1 g / L-60 g / L.
[0021] Preferably, the mode of multi-stage extraction in S2 comprises: countercurrent extraction and fractional extraction.
[0022] Preferably, the extraction stage number of the multi-stage extraction in S2 is 1-40, the extraction temperature is 10℃-90℃, and the volume flow ratio of the organic phase containing the extractant to the iron-containing leaching solution (extraction phase ratio) is 0.1-10:1. The iron-containing leaching solution obtained by acid leaching treatment of different acid solutions on the iron-containing raw material is different. The composition of the organic phase containing the extractant can be determined according to different iron-containing leaching solutions, and the extraction stage number, the extraction temperature and the volume flow ratio of the organic phase containing the extractant to the iron-containing leaching solution (extraction phase ratio) can be determined according to the extraction capacity of the organic phase containing the extractant.
[0023] Preferably, in S3, the washing agent comprises: water, a sulfuric acid solution and a hydrochloric acid solution; the volume flow ratio of the washing agent to the iron-loaded organic phase (washing phase ratio) is 0.1-25:1; and the washing temperature is 10℃-80℃.
[0024] Preferably, the oxalic acid stripping agent in S4 comprises: an oxalic acid solution, an oxalate solution, a mixed solution of oxalic acid and oxalate, and a mixed solution of oxalic acid and a reducing agent; the concentration of the oxalic acid solution and the oxalate solution is 0.01 mol / L-1.0 mol / L respectively; the concentration of oxalate in the mixed solution of oxalic acid and oxalate is 0.01 mol / L-1.0 mol / L; and the concentration of oxalic acid in the mixed solution of oxalic acid and a reducing agent is 0.01 mol / L-1.0 mol / L, and the amount of the reducing agent is 0.8-1.2 times of the stoichiometric amount of the reduction. + The stoichiometric amount of the reduction.
[0025] Preferably, the reduction conversion treatment in S5 comprises: a heating treatment, a photocatalytic treatment and a reducing agent reduction treatment.
[0026] In summary, the present application provides a solvent extraction preparation method of high-purity ferrous oxalate, which has the following beneficial effects compared with the traditional technology:
[0027] (1) The present application solves the problem that the purity of ferrous oxalate is limited by the purity of raw materials by sequentially performing acid leaching treatment, multi-stage extraction treatment and washing treatment on the iron-containing raw material.
[0028] (2) The present application selectively extracts iron from the leaching liquid of a plurality of iron-containing raw materials or the iron-containing mixed liquid containing a plurality of metal ions, and through extraction, washing of the iron-loaded organic phase and back extraction, ferrous oxalate with a purity greater than 99.99% is obtained, and the yield of iron is greater than 98%, realizing the preparation of ferrous oxalate with high purity, low pollution, low energy consumption and low production cost.
[0029] (3) The present application uses solvent extraction method for complex iron-containing resources, which not only utilizes resources but also guarantees product purity, meeting the demand of high-end market.
[0030] The technical method of the present application will be further described in detail below by means of the accompanying drawings and examples. BRIEF DESCRIPTION OF DRAWINGS
[0031] Figure 1 The flow chart of the solvent extraction preparation method of high-purity ferrous oxalate according to the present application. DETAILED DESCRIPTION
[0032] The technical method of the present application will be further described in detail below by means of the accompanying drawings and examples.
[0033] The following description of at least one example embodiment is merely exemplary in nature and is in no way intended to limit the application or its application or uses.
[0034] In all examples shown and discussed herein, any specific values should be interpreted as merely exemplary, and not as a limitation. Thus, other examples of example embodiments can have different values.
[0035] Unless otherwise defined, technical or scientific terms used in the present application shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.
[0036] The present application provides a solvent extraction preparation method of high-purity ferrous oxalate, as shown in Figure 1 The method comprises the following steps:
[0037] S1, acid leaching treatment is performed on the iron-containing raw material by using an acid solution, and an iron-containing leaching liquid is obtained by filtration. The acid solution is at least one of sulfuric acid solution, hydrochloric acid solution and hydrofluoric acid. The iron-containing raw material is at least one of iron minerals, industrial iron-containing waste slag, pickling waste liquid, red mud leaching liquid and ilmenite leaching liquid.
[0038] S2, multi-stage extraction is performed on the iron-containing leaching solution with the organic phase containing the extractant to selectively extract iron and obtain an organic phase loaded with iron. The concentration of iron ions in the organic phase loaded with iron is 0.1 g / L-60 g / L.
[0039] The extractant includes an acidic extractant, a neutral extractant and a basic extractant. Specifically, the acidic extractant includes a sulfonic acid extractant, a carboxylic acid extractant and an acidic phosphorus-containing extractant; the neutral extractant includes a neutral phosphorus-containing extractant, an alcohol extractant, a ketone extractant and a sulfoxide extractant; the basic extractant is an amine extractant, which includes hydrophobic primary amines, secondary amines and quaternary amine salts, and the number of carbon atoms of the amine extractant is 6-30 and the number of nitrogen atoms is 1-3.
[0040] The mode of the multi-stage extraction includes countercurrent extraction and fractional extraction. The number of extraction stages is 1-40, the extraction temperature is 10℃-90℃, and the volume flow ratio of the organic phase containing the extractant to the iron-containing leaching solution (extraction phase ratio) is 0.1-10:1.
[0041] S3, the organic phase loaded with iron is washed with a washing agent to obtain a purified organic phase. The washing agent includes water, a sulfuric acid solution and a hydrochloric acid solution. The volume flow ratio of the washing agent to the organic phase loaded with iron (washing phase ratio) is 0.1-25:1, and the washing temperature is 10℃-80℃.
[0042] S4, the purified organic phase is stripped with an oxalic acid stripping agent to obtain an iron oxalate stripping solution. The oxalic acid stripping agent includes an oxalic acid solution, an oxalate solution, a mixed solution of oxalic acid and oxalate, and a mixed solution of oxalic acid and a reducing agent. The concentration of the oxalic acid solution and the oxalate solution is 0.01 mol / L-1.0 mol / L; the concentration of oxalate in the mixed solution of oxalic acid and oxalate is 0.01 mol / L-1.0 mol / L; the concentration of oxalic acid in the mixed solution of oxalic acid and a reducing agent is 0.01 mol / L-1.0 mol / L, and the amount of the reducing agent is 0.8-1.2 times of the stoichiometric amount of the reducing agent required for the reduction of Fe3+. + to the stoichiometric amount of the reducing agent required for the reduction of Fe3+.
[0043] S5, the iron oxalate stripping solution is subjected to reduction conversion treatment to obtain high-purity ferrous oxalate. The reduction conversion treatment includes heating treatment, photocatalytic treatment and reducing agent reduction treatment. Further, the reducing agent is hydroxyethyl mercaptan.
[0044] An embodiment of the solvent extraction method for preparing high-purity ferrous oxalate provided in the present application is as follows:
[0045] Embodiment 1
[0046] A solvent extraction method for preparing high-purity ferrous oxalate, the steps are as follows:
[0047] S1, the iron hydroxide waste residue produced by alkali method is treated by acid leaching with sulfuric acid solution, and an iron-containing leaching solution with an iron ion concentration of 50 g / L and a total rare earth ion concentration of 5 g / L is obtained by filtration.
[0048] S2, the pH value of the iron-containing leaching solution is adjusted to 0.5 with the iron hydroxide waste residue, then the dinonyl naphthalene sulfonic acid is prepared into an organic phase with a volume concentration of 36% with the de-aromatic solvent oil (D80) as a diluent, as an extractant, the iron-containing leaching solution is extracted by 5-stage countercurrent extraction under the conditions of extraction temperature 40℃ and extraction phase ratio 3:1, and the iron-loaded organic phase is obtained by selective extraction of iron.
[0049] S3, the iron-loaded organic phase is washed by 15-stage washing with 0.25 mol / L dilute sulfuric acid solution under the conditions of washing phase ratio 15:1 and temperature 40℃, and a purified organic phase is obtained.
[0050] S4, a mixed solution of oxalic acid and sodium oxalate with an oxalate concentration of 1.0 mol / L is used as a stripping agent, and the purified organic phase is stripped by 5-stage countercurrent stripping under the conditions of stripping phase ratio (volume flow ratio of stripping agent to loaded organic phase) 2:1 and temperature 80℃, and an iron oxalate stripping solution is obtained.
[0051] S5, the iron oxalate stripping solution is heated to 90℃, and ferrous oxalate is obtained. The purity of the ferrous oxalate is 99.99%, and the yield is 98.2%.
[0052] Example 2
[0053] A solvent extraction method for preparing high-purity ferrous oxalate, the steps are as follows:
[0054] S1, an iron-containing waste residue is treated by acid leaching with hydrochloric acid solution, and a hydrochloric acid solution with an iron ion concentration of 15 g / L is obtained by filtration, and the acidity (hydrochloric acid equivalent concentration) of the hydrochloric acid solution is 4.3 mol / L, then hydrogen peroxide is added to oxidize ferrous ions to trivalent iron ions, and an iron-containing leaching solution is obtained.
[0055] The iron-containing waste residue used in Example 2 is denoted as iron-containing waste residue 1, and the content of each component (mass fraction / wt%) of the iron-containing waste residue 1 is shown in Table 1.
[0056] Table 1 Content of each component (mass fraction / wt%) of iron-containing waste residue 1
[0057] CaCl2 MgCl2 MnCl2 KCl NaCl Al2O3 CaO MgO MnO 6.74 15.82 11.86 0.10 22.64 0.47 1.18 0.46 0.92 SiO2 ∑Ti Fe2O3 C V FeCl2 FeCl3 Water insolubles 0.84 0.58 3.16 13.61 0.1 6.72 2.84 22.29
[0058] S2, 8-stage countercurrent extraction of the iron-containing leaching solution is performed using a neutral extractant, Methyl Isobutyl Ketone (MIBK), at an extraction temperature of 25°C and an extraction phase ratio of 4:1, to obtain an iron-loaded organic phase by selectively extracting iron.
[0059] S3, 12-stage washing of the iron-loaded organic phase is performed using a 1 mol / L hydrochloric acid solution at a washing phase ratio of 10:1 and a temperature of 25°C to obtain a purified organic phase.
[0060] S4, 6-stage countercurrent stripping of the purified organic phase is performed using a mixed solution of oxalic acid and sodium oxalate with an oxalate concentration of 0.62 mol / L as a stripping agent at a stripping phase ratio of 3:1 and a temperature of 75°C to obtain an iron oxalate stripping solution.
[0061] S5, heating the iron oxalate stripping solution to 90°C to obtain ferrous oxalate. The purity of the ferrous oxalate is 99.991% and the yield is 98.1%.
[0062] Example 3
[0063] A solvent extraction method for preparing high-purity ferrous oxalate, the steps are as follows:
[0064] S1, acid leaching treatment of a certain iron-containing waste residue is performed using a hydrochloric acid solution, filtration to obtain a hydrochloric acid solution with an iron ion concentration of 48 g / L, the acidity (hydrochloric acid equivalent concentration) of the hydrochloric acid solution is 6.6 mol / L, then hydrogen peroxide is added to oxidize ferrous ions to trivalent iron ions to obtain an iron-containing leaching solution.
[0065] The iron-containing waste residue used in Example 3 is denoted as iron-containing waste residue 2, the content of each component of the iron-containing waste residue 2 (mass fraction / wt%) is shown in Table 2.
[0066] Table 2 Content of each component of iron-containing waste residue 2 (mass fraction / wt%)
[0067] AlCl3 CaCl2 MgCl2 MnCl2 KCl NaCl Al2O3 CaO 15.84 0.81 1.26 2.02 0.39 12.86 2.53 0.34 MnO SiO2 ∑Ti Fe2O3 C V FeCl2 FeCl3 0.39 5.99 5.98 3.41 1.59 0.75 1.43 34.74
[0068] S2, 12-stage countercurrent extraction of the iron-containing leaching solution is performed using a 8-12 carbon atom Guerbet alcohol at an extraction temperature of 65°C and an extraction phase ratio of 3:1 to obtain an iron-loaded organic phase by selectively extracting iron.
[0069] S3, 25-stage washing of the iron-loaded organic phase is performed using a 5 mol / L hydrochloric acid solution at a washing phase ratio of 15:1 and a temperature of 65°C to obtain a purified organic phase.
[0070] S4, the mixed solution of oxalic acid and sodium oxalate with oxalate concentration of 0.62 mol / L is used as stripping agent, and the purified organic phase is subjected to 4-stage countercurrent stripping under the conditions of stripping phase ratio of 3:1 and temperature of 70 DEG C to obtain iron oxalate stripping solution.
[0071] S5, the iron oxalate stripping solution is heated to 90 DEG C to obtain ferrous oxalate. The purity of ferrous oxalate is 99.994%, and the yield is 98.5%.
[0072] Example 4
[0073] A solvent extraction method for preparing high-purity ferrous oxalate, the steps are as follows:
[0074] S1, the pickling waste liquid is used as the iron-containing leaching solution. The pickling waste liquid comprises: 28.30 g / L of iron, 19.16 g / L of chromium, 4.96 g / L of aluminum, 6.26 g / L of manganese, 0.15 g / L of silicon, 0.14 g / L of vanadium, 0.51 g / L of calcium and 12.42 g / L of nickel.
[0075] S2, the ether is used as the extractant, and 4-stage countercurrent extraction is carried out under the conditions of temperature of 60 DEG C, acidity of 1.52 mol / L, extraction phase ratio of 3:1 and extraction time of 5 min, and the iron-loaded organic phase is obtained after extraction equilibrium, the residual water iron is 0.14 g / L, and the iron extraction rate is 98.06%.
[0076] S3, the iron-loaded organic phase is subjected to 5-stage washing using 2 mol / L hydrochloric acid solution under the conditions of washing phase ratio of 12:1 and temperature of 60 DEG C to obtain the purified organic phase.
[0077] S4, the mixed solution of oxalic acid and sodium oxalate with oxalate concentration of 0.5 mol / L is used as stripping agent, and the purified organic phase is subjected to 8-stage countercurrent stripping under the conditions of stripping phase ratio of 3:1 and temperature of 60 DEG C to obtain iron oxalate stripping solution.
[0078] S5, the iron oxalate stripping solution is subjected to photochemical catalytic reduction to obtain ferrous oxalate. The purity of ferrous oxalate is 99.992%, and the yield is 97.38%.
[0079] Example 5
[0080] A solvent extraction method for preparing high-purity ferrous oxalate, the steps are as follows:
[0081] S1, the ilmenite leaching solution is used as the iron-containing leaching solution. The ilmenite leaching solution comprises: 26.36 g / L of iron, 0.32 g / L of chromium, 0.46 g / L of aluminum, 1.26 g / L of manganese, 0.05 g / L of silicon, 0.44 g / L of vanadium, 2.14 g / L of calcium and 60.71 g / L of titanium.
[0082] S2, 8-stage countercurrent extraction was carried out under the conditions of tributyl phosphate (TBP) as the extractant, temperature 30℃, acidity 4.62 mol / L, extraction phase ratio 2.5:1 and extraction time 5 min, to obtain the organic phase loaded with iron after extraction equilibrium, with residual water iron 0.05 g / L and iron extraction rate 99.8%.
[0083] S3, 5-stage washing was carried out on the organic phase loaded with iron under the conditions of 2 mol / L hydrochloric acid solution as the washing agent, washing phase ratio 18:1 and temperature 30℃, to obtain the purified organic phase.
[0084] S4, the mixed solution of oxalic acid and sodium oxalate with oxalate concentration 0.5 mol / L was used as the stripping agent, 8-stage countercurrent stripping extraction was carried out on the purified organic phase under the conditions of stripping phase ratio 3:1 and temperature 65℃, to obtain the iron oxalate stripping solution.
[0085] S5, photochemical catalytic reduction was carried out on the iron oxalate stripping solution to obtain ferrous oxalate. The purity of the ferrous oxalate was 99.992% and the yield was 98.18%.
[0086] Example 6
[0087] A solvent extraction method for preparing high-purity ferrous oxalate, the steps are as follows:
[0088] S1, the red mud leaching solution was used as the iron-containing leaching solution. The red mud leaching solution included: 12.49 g / L of iron, 0.12 g / L of chromium, 25.12 g / L of aluminum, 0.47 g / L of silicon, 0.84 g / L of calcium and 0.42 g / L of titanium.
[0089] S2, 3-stage countercurrent extraction was carried out under the conditions of di(2-ethylhexyl)phosphoric acid (P204) as the extractant, temperature 30℃, acidity 0.22 mol / L, extraction phase ratio 2:1 and extraction time 5 min, to obtain the organic phase loaded with iron after extraction equilibrium, with residual water iron 0.06 g / L and iron extraction rate 99.5%.
[0090] S3, 10-stage washing was carried out on the organic phase loaded with iron under the conditions of 0.5 mol / L sulfuric acid solution as the washing agent, washing phase ratio 15:1 and temperature 30℃, to obtain the purified organic phase.
[0091] S4, the mixed solution of oxalic acid and sodium oxalate with oxalate concentration 0.5 mol / L was used as the stripping agent, 6-stage countercurrent stripping extraction was carried out on the purified organic phase under the conditions of stripping phase ratio 4:1 and temperature 65℃, to obtain the iron oxalate stripping solution.
[0092] S5, the ferric oxalate stripping solution is reduced by hydroxyethyl mercaptan to obtain ferrous oxalate. The purity of the ferrous oxalate is 99.994%, and the yield is 98.26%.
[0093] Example 7
[0094] A solvent extraction method for preparing high-purity ferrous oxalate is provided, and the steps are as follows:
[0095] S1, the sulfuric acid leaching solution of red mud is used as the iron-containing raw material solution. The red mud leaching solution includes 23.18 g / L of iron, 0.20 g / L of chromium, 39.43 g / L of aluminum, 0.26 g / L of silicon, 0.52 g / L of calcium, and 0.89 g / L of titanium.
[0096] S2, tri-dodecylamine is used as an extractant, and kerosene is used as a diluent, and the volume ratio of the two is 5:15. Under the conditions of a temperature of 50°C, an acidity of 0.42 mol / L, an extraction phase ratio of 3:1, and an extraction time of 5 min, six-stage countercurrent extraction is carried out, and after the extraction equilibrium, the organic phase loaded with iron is obtained, and the residual water iron is 0.12 g / L, and the iron extraction rate is 99.5%.
[0097] S3, the organic phase loaded with iron is washed by using a 0.5 mol / L sulfuric acid solution under the conditions of a washing phase ratio of 15:1 and a temperature of 50°C, and a purified organic phase is obtained.
[0098] S4, a mixed solution of oxalic acid and sodium oxalate with an oxalate concentration of 0.5 mol / L is used as a stripping agent, and the purified organic phase is subjected to eight-stage countercurrent stripping extraction under the conditions of a stripping phase ratio of 3:1 and a temperature of 65°C, and a ferric oxalate stripping solution is obtained.
[0099] S5, the ferric oxalate stripping solution is reduced by heating at 90°C to obtain ferrous oxalate. The purity of the ferrous oxalate is 99.987%, and the yield is 98.33%.
[0100] The solvent extraction method for preparing high-purity ferrous oxalate provided by the application solves the problem that the purity of ferrous oxalate is limited by the purity of the raw material, and ferrous oxalate with a purity greater than 99.99% is obtained, and the yield of iron is greater than 98%, realizing the preparation of high-purity, low-pollution, low-energy-consumption, and low-production-cost ferrous oxalate, which not only utilizes resources but also guarantees product purity, meeting the needs of the high-end market.
[0101] Finally, it should be noted that the above examples are only used to illustrate the technical method of the application and not to limit it. Although the application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical method of the application can still be modified or replaced equivalently, and these modifications or equivalent replacements should not make the modified technical method deviate from the spirit and scope of the technical method of the application.
Claims
1. A process for the preparation of high purity ferrous oxalate by solvent extraction, characterized in that, The method comprises the following steps: S1, using an acid solution to perform acid leaching treatment on an iron-containing raw material, and filtering to obtain an iron-containing leaching solution; S2, using an organic phase containing an extractant to perform multi-stage extraction on the iron-containing leaching solution, selectively extracting iron, and obtaining an organic phase loaded with iron; S3, using a detergent to wash the organic phase loaded with iron, and obtaining a purified organic phase; S4, using an oxalic acid-based stripping agent to perform stripping extraction on the purified organic phase, and obtaining an iron oxalate stripping solution; S5, performing reduction conversion treatment on the iron oxalate stripping solution, and obtaining high-purity ferrous oxalate.
2. The process for the preparation of high purity ferrous oxalate by solvent extraction as claimed in claim 1 wherein, The acid solution in S1 is at least one of a sulfuric acid solution, a hydrochloric acid solution, and a hydrofluoric acid solution.
3. The process for the preparation of high purity ferrous oxalate by solvent extraction as claimed in claim 1 wherein, The iron-containing raw material in S1 is at least one of an iron mineral, an industrial iron-containing waste residue, an acid washing waste liquid, a red mud leaching solution, and an ilmenite leaching solution.
4. The process for the preparation of high purity ferrous oxalate by solvent extraction as claimed in claim 1 wherein, The extractant in S2 includes an acid extractant, a neutral extractant, and an alkaline extractant; the acid extractant includes a sulfonic acid extractant, a carboxylic acid extractant, and an acid phosphorus-containing extractant; the neutral extractant includes a neutral phosphorus-containing extractant, an alcohol extractant, a ketone extractant, and a sulfoxide extractant; the alkaline extractant is an amine extractant, including hydrophobic primary amines, secondary amines, and quaternary amine salts; the amine extractant has a carbon atom number of 6-30 and a nitrogen atom number of 1-3.
5. The process for the preparation of high purity ferrous oxalate by solvent extraction as claimed in claim 1 wherein, The iron ion concentration in the organic phase loaded with iron is 0.1 g / L-60 g / L.
6. The process for the preparation of high purity ferrous oxalate by solvent extraction as claimed in claim 1 wherein, The mode of multi-stage extraction in S2 includes countercurrent extraction and fractional extraction.
7. The process for the preparation of high purity ferrous oxalate by solvent extraction as claimed in claim 1 wherein, The number of extraction stages in S2 is 1-40, the extraction temperature is 10°C-90°C, and the volume flow ratio of the organic phase containing the extractant to the iron-containing leaching solution is 0.1-10:
1.
8. The process for the preparation of high purity ferrous oxalate by solvent extraction as claimed in claim 1 wherein, In S3, the detergent includes water, a sulfuric acid solution, and a hydrochloric acid solution; the volume flow ratio of the detergent to the organic phase loaded with iron is 0.1-25:1; and the washing temperature is 10°C-80°C.
9. The process for the preparation of high purity ferrous oxalate by solvent extraction as claimed in claim 1 wherein, The oxalic acid stripping agent in S4 includes: oxalic acid solution, oxalate solution, mixed solution of oxalic acid and oxalate, and mixed solution of oxalic acid and reducing agent; the concentration of the oxalic acid solution and the oxalate solution is 0.01-1.0 mol / L respectively; the concentration of oxalate in the mixed solution of oxalic acid and oxalate is 0.01-1.0 mol / L; the concentration of oxalic acid in the mixed solution of oxalic acid and reducing agent is 0.01-1.0 mol / L, and the amount of reducing agent is 0.8-1.2 times of the stoichiometric amount of reduction. + The concentration of oxalic acid in the mixed solution of oxalic acid and reducing agent is 0.01-1.0 mol / L, and the amount of reducing agent is 0.8-1.2 times of the stoichiometric amount of reduction.
10. The process for the preparation of high purity ferrous oxalate by solvent extraction as claimed in claim 1 wherein, The reduction conversion treatment in S5 includes heating treatment, photocatalytic treatment, and reduction agent reduction treatment.