Method for preparing iron oxide red by using iron-containing electroplating waste acid solution
By using a compound of soluble sulfides and permanganates to remove impurities from electroplating waste acid, and combining this with hyperbranched surfactants and a segmented temperature-controlled calcination process, the problem of interference from impurity ions in electroplating waste acid was solved. This enabled the preparation of high-purity, uniformly sized iron oxide red, reducing energy consumption and the risk of secondary pollution, and meeting the standards for high-quality pigments.
Patent Information
- Application Number
- CN202610375823.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-25
- Publication Date
- 2026-05-19
AI Technical Summary
Existing technologies are unable to effectively remove impurity ions from electroplating waste acid solutions, resulting in low purity and uneven particle size of iron oxide red, which makes it difficult to meet the standards for high-quality pigments. Furthermore, existing methods pose risks of high energy consumption and secondary pollution.
Impurities were removed by using a mixture of soluble sulfides and permanganates, and hyperbranched surfactants were added as particle size retainers. The particle size and crystal transformation were controlled by a segmented temperature-controlled calcination process. Nanocrystalline seeds were used to guide crystal growth and reduce the calcination temperature.
This method enables the preparation of high-purity, uniformly sized iron oxide red, reduces energy consumption and impurity residue, meets the requirements of high-quality pigments, and avoids secondary pollution.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of electroplating waste liquid recycling and treatment technology, specifically relating to a method for preparing iron oxide red using iron-containing electroplating waste acid liquid. Background Technology
[0002] Electroplating is a crucial component of my country's manufacturing industry, generating large quantities of waste acid containing heavy metal ions during its production process. Taking iron-containing waste acid as an example, its main components are hydrochloric acid and iron salts such as ferrous chloride and ferric chloride. Direct discharge without proper treatment will cause severe soil acidification and water pollution. With increasingly stringent environmental regulations, achieving the harmless treatment and resource utilization of this type of waste acid has become a pressing technical challenge for the electroplating industry.
[0003] Currently, the main methods for treating iron-containing waste acid include chemical precipitation, evaporation concentration, and oxidation. Chemical precipitation typically involves adding an alkali to adjust the pH, causing iron ions to precipitate as hydroxides, which are then dehydrated and transported for disposal. However, this method consumes large amounts of alkali, resulting in high treatment costs, and the generated sludge is hazardous waste with expensive subsequent disposal, failing to truly achieve resource utilization. While evaporation concentration can recover some acid, it requires large equipment investments, consumes high energy, and struggles to address the accumulation of impurities in the concentrated solution, limiting its widespread application.
[0004] In the preparation of iron oxide red pigment from iron-containing wastewater, existing technologies mainly employ extraction-calcination or air oxidation-hydrothermal methods. While the extraction-calcination method can yield high-purity products, its complex process requires organic extractants, carries risks of solvent loss and secondary pollution, and is highly sensitive to iron ion concentration in the raw materials, making it difficult to directly treat low-concentration electroplating waste acid. Although the air oxidation-hydrothermal method can control the particle size and morphology of the product, it is sensitive to the purity of the raw materials. Impurities such as zinc, copper, and nickel often present in electroplating waste acid can interfere with the formation of intermediate products, leading to unstable pigment hue and large performance fluctuations, making it difficult to meet the standardized production requirements of industrial pigments.
[0005] The neutralization-calcination method has potential applications in the treatment of iron-containing wastewater due to its short process and convenient operation. However, existing neutralization-calcination processes are mostly designed for etching wastewater with relatively simple compositions, and have significant shortcomings when directly applied to electroplating waste acid with complex compositions: on the one hand, impurity ions in the waste acid are prone to co-precipitate with iron ions during the neutralization process, resulting in low purity and excessive impurity content of the calcined iron oxide red; on the other hand, if the pH value is not precisely controlled during the neutralization precipitation process, the particle size distribution of the ferric hydroxide precipitate is uneven, directly affecting the particle size consistency and color stability of the calcined product. The product often only reaches the level of low-end pigments and cannot meet the market demand for high-quality iron oxide red.
[0006] In summary, developing a method for preparing iron oxide red that is tailored to the characteristics of electroplating waste acid, can effectively remove impurities, stably control product particle size, and is economically feasible has become an urgent technical problem to be solved in this field. Summary of the Invention
[0007] The purpose of this invention is to provide a method for preparing iron oxide red using iron-containing electroplating waste acid, so as to solve the problem of low quality of iron oxide red.
[0008] The objective of this invention can be achieved through the following technical solutions: This invention provides a method for preparing iron oxide red using iron-containing electroplating waste acid, comprising the following steps: The first step is to add an iron source to the acidic iron-containing electroplating waste liquid to consume the acid in the waste liquid; then, impurity removal treatment is carried out to remove interfering ions and obtain a high-content ferrous solution. The second step involves diluting the high-content ferrous solution to a ferrous ion concentration of 0.5-1.5 mol / L, neutralizing it with an alkaline precipitant, and adding a particle size maintainer, which is a hyperbranched surfactant; then oxidizing it with air for 20-30 minutes to obtain the precursor slurry. The third step involves pressing and washing the precursor slurry to remove chloride and sodium ions, resulting in a filter cake. The filter cake is then dispersed in water, and 0.1%–1% of nano-sized α-Fe2O3 seed crystals are added. After stirring evenly, the mixture is dried. The dried material is then placed in a muffle furnace and calcined using segmented temperature control to obtain iron oxide red.
[0009] In some possible implementations, the hyperbranched surfactant contains sulfonate groups. Besides its excellent dispersing effect, the particle size retainer introduces sulfonate groups into its structure, which can introduce sulfonate groups onto the precipitate surface, improving calcination efficiency, reducing calcination temperature, and leaving no residue. During the precipitation stage, the sulfonic acid groups in the particle size retainer achieve efficient dispersion through the synergistic effect of electrostatic repulsion and steric hindrance; during the calcination stage, the SO2 generated by the thermal decomposition of the sulfonic acid groups forms a locally reducing micro-atmosphere, inducing Fe... 3+ The process reduces and promotes the crystal transformation of γ-Fe₂O₃ to α-Fe₂O₃, thereby lowering the calcination temperature by 100-150℃ and significantly saving energy. Simultaneously, the sulfonic acid groups are completely removed in gaseous form at high temperature. ICP testing shows that the sulfur residue in the final product is less than 0.03%, which has no adverse effect on the purity and color of the iron oxide red.
[0010] In some possible implementations, the particle size retainer is prepared by the following steps: Hydroxyl-terminated hyperbranched polyester and sulfosuccinic acid were mixed and refluxed at 140-145℃ under nitrogen protection for 3-4 hours. After the reaction was completed, the mixture was dried to obtain a particle size retainer.
[0011] The hydroxyl-terminated hyperbranched polyester is one of H101 and H102. The molar ratio of hydroxyl-terminated hyperbranched polyester to sulfosuccinic acid is 1:2-5.
[0012] In some possible implementations, the amount of particle size retainer added is Fe² + 1%–5% of the quality.
[0013] In some possible implementations, the acidic iron-containing electroplating waste liquid includes free acid (HCl) and ferrous ions (Fe²⁺). + ), trivalent iron ions (Fe³⁺) + ) and impurity metal ions (including but not limited to Mn²) + Cr³ + Cu² + Ni² + Zn² + ).
[0014] In some possible implementations, the Mn in the acidic iron-containing electroplating waste liquid 2+ 0.5-1.5 g / L; Cr 3+ 0.8-1.8 g / L; Cu 2+ +Zn 2+ + Ni 2+ (Total) 0.2-0.9 g / L.
[0015] In some possible implementations, the impurity removal agent used in the impurity removal process to remove interfering ions is a mixture of soluble sulfides and permanganates; By controlling the reaction pH to 5.0-6.5, temperature to 40-60℃, and reaction time to 1-2 hours, nonionic polyacrylamide, a flocculant, is added. The amount of flocculant added is 0.5%-2% of the mass of the acidic iron-containing electroplating waste liquid. After filtration, a high-ferrous content solution is obtained.
[0016] The impurity removal treatment removes Cu from the waste liquid 2+ Zn 2+ Ni 2+ When sulfide precipitates form, Mn 2+ The permanganate is oxidized to form MnO2 precipitate. Simultaneously, the newly formed MnO2 reacts with Cr in the solution. 3+Heavy metal ions have strong adsorption and co-precipitation effects. They synergistically remove impurity ions, resulting in impurity ion residues of less than 0.1%. In addition, although the newly formed MnO2 has adsorption properties, its particle size is very small and loose, and it settles slowly by gravity alone. Therefore, adding a small amount of nonionic polyacrylamide as a flocculant accelerates flocculation.
[0017] In some possible implementations, the soluble sulfide is sodium sulfide and the permanganate is potassium permanganate; the mass ratio of the soluble sulfide to the permanganate is 2.5-4:1.
[0018] In some possible implementations, the alkaline precipitant is one of ammonia, sodium hydroxide solution, and ammonium carbonate solution.
[0019] In some possible implementations, segmented calcination is used: first, the temperature is increased to 300-400℃ at a heating rate of 2-5℃ / min and held for 1-2 hours to allow the precursor to be fully dehydrated; then, the temperature is increased to 500-600℃ at a heating rate of 5-10℃ / min and held for 2-3 hours.
[0020] In some possible implementations, the iron source is elemental iron powder or iron oxide.
[0021] The beneficial effects of this invention are: This invention provides a method for preparing iron oxide red using iron-containing electroplating waste acid solution. The method includes the following steps: removing impurities from the iron-containing electroplating waste acid solution to remove interfering ions, thereby improving the efficiency of subsequent treatment. The impurity removal treatment uses a mixture of soluble sulfide and permanganate as the impurity removal agent, achieving effective removal of impurity ions through the synergistic effect of the two.
[0022] In the subsequent alkalization, neutralization, and precipitation process, a particle size control agent is added to the reaction system. This particle size control agent is a hyperbranched surfactant, which inhibits crystal nucleus aggregation through steric hindrance and introduces nanocrystal seeds before calcination, providing heterogeneous nucleation sites, guiding crystal growth, and reducing the nucleation barrier. Simultaneously, a segmented temperature control method is employed to ensure that the precursor dehydration and crystal transformation processes proceed smoothly, avoiding abnormal grain growth or sintering due to localized overheating. Through this combination of techniques, precise control of the product particle size is achieved. Detailed Implementation
[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0024] Obviously, the following description is merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios without any inventive effort. Furthermore, it is understood that although the effort involved in such development may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.
[0025] However, there may be instances where unnecessary detailed descriptions are omitted. For example, detailed descriptions of well-known matters or repetitive descriptions of essentially the same structure may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the following description is provided to enable those skilled in the art to fully understand this application and is not intended to limit the subject matter of the claims.
[0026] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions, and all technical features and optional technical features of this application can be combined to form new technical solutions.
[0027] The following is a detailed description of a method for preparing iron oxide red using iron-containing electroplating waste acid solution, according to an embodiment of this application.
[0028] The following is a detailed description with reference to specific examples.
[0029] Example 1
[0030] This embodiment provides a method for preparing iron oxide red using iron-containing electroplating waste acid solution, including the following steps: Step 1: Add excess elemental iron powder to the acidic iron-containing electroplating waste liquid; then perform impurity removal treatment to remove interfering ions, obtaining a high-content ferrous solution; the acidic iron-containing electroplating waste liquid contains Mn 2+ 0.5 g / L; Cr 3+ 0.8 g / L; Cu 2+ +Zn 2+ +Ni 2+ (Total) 0.2 g / L; The impurity removal agent used to remove interfering ions in the impurity removal treatment is a compound mixture of soluble sulfide and permanganate; the soluble sulfide is sodium sulfide, and the permanganate is potassium permanganate; the ratio of sodium sulfide to acidic iron-containing electroplating waste liquid is 1 g: 1 L; the ratio of permanganate to acidic iron-containing electroplating waste liquid is 3.5 g: 1 L; By controlling the reaction pH to 6.5, temperature to 50℃, and reaction time to 12h, nonionic polyacrylamide, a flocculant, was added. The amount of flocculant added was 0.5% of the mass of the acidic iron-containing electroplating waste liquid. After filtration, a high-ferrous content solution was obtained.
[0031] The second step involves diluting the high-concentration ferrous solution to a ferrous ion concentration of 1 mol / L, neutralizing it with an alkaline precipitant, and then adding a particle size maintainer, which is a hyperbranched surfactant. Air is then introduced for 30 minutes to obtain the precursor slurry. The amount of particle size maintainer added is Fe²⁺. + 3% by mass; the alkaline precipitant is ammonia. The particle size control agent is prepared by the following steps: Hydroxyl-terminated hyperbranched polyester and sulfosuccinic acid were mixed and refluxed at 140℃ under nitrogen protection for 4 hours. After the reaction was completed, the mixture was dried to obtain a particle size maintainer. The hydroxyl-terminated hyperbranched polyester was H101; the molar ratio of the hydroxyl-terminated hyperbranched polyester to sulfosuccinic acid was 1:2.
[0032] The third step involves pressing and washing the precursor slurry to obtain a filter cake. The filter cake is then dispersed in water, and 0.5% (by weight of the filter cake) of nano-sized α-Fe₂O₃ seed crystals are added. After stirring evenly, the mixture is dried. The dried material is then placed in a muffle furnace and calcined using a segmented temperature-controlled method to obtain iron oxide red. The segmented calcination process involves first heating to 350°C at a rate of 5°C / min and holding for 2 hours to fully dehydrate the precursor; then heating to 550°C at a rate of 5°C / min and holding for 2 hours.
[0033] Example 2
[0034] This embodiment provides a method for preparing iron oxide red using iron-containing electroplating waste acid solution, including the following steps: The first step is to add an excess of elemental iron powder to the acidic iron-containing electroplating waste liquid; then, impurity removal treatment is carried out to remove interfering ions, resulting in a high-content ferrous solution. The acidic iron-containing electroplating waste liquid contains Mn 2+ 1g / L; Cr 3+ 1.2 g / L; Cu 2+ +Zn 2+ + Ni 2+ (Total) 0.5 g / L; The impurity removal agent used to remove interfering ions in the impurity removal treatment is a compound mixture of soluble sulfide and permanganate; the soluble sulfide is sodium sulfide, and the permanganate is potassium permanganate; the ratio of sodium sulfide to acidic iron-containing electroplating waste liquid is 2 g: 1 L; the ratio of permanganate to acidic iron-containing electroplating waste liquid is 6 g: 1 L; By controlling the reaction pH to 6.5, temperature to 50℃, and reaction time to 2 hours, nonionic polyacrylamide was added as a flocculant. The amount of flocculant added was 0.5% of the mass of the acidic iron-containing electroplating waste liquid. After filtration, a high-ferrous content solution was obtained.
[0035] The remaining raw materials and preparation process are the same as in Example 1.
[0036] Example 3
[0037] This embodiment provides a method for preparing iron oxide red using iron-containing electroplating waste acid solution, including the following steps: The first step is to add an excess of elemental iron powder to the acidic iron-containing electroplating waste liquid; then, impurity removal treatment is carried out to remove interfering ions, resulting in a high-content ferrous solution. The acidic iron-containing electroplating waste liquid contains Mn 2+ 1.5g / L; Cr 3+ 1.8 g / L; Cu 2+ +Zn 2+ + Ni 2+ (Total) 0.9 g / L; The impurity removal agent used to remove interfering ions in the impurity removal treatment is a compound mixture of soluble sulfide and permanganate; the soluble sulfide is sodium sulfide, and the permanganate is potassium permanganate; the ratio of sodium sulfide to acidic iron-containing electroplating waste liquid is 4 g: 1 L; the ratio of permanganate to acidic iron-containing electroplating waste liquid is 9 g: 1 L; By controlling the reaction pH to 6.5, temperature to 50℃, and reaction time to 2 hours, nonionic polyacrylamide was added as a flocculant. The amount of flocculant added was 0.5% of the mass of the acidic iron-containing electroplating waste liquid. After filtration, a high-ferrous content solution was obtained.
[0038] The remaining raw materials and preparation process are the same as in Example 1.
[0039] Example 4
[0040] This embodiment provides a method for preparing iron oxide red using iron-containing electroplating waste acid. The difference between this embodiment and Embodiment 1 lies in the preparation process of the particle size retainer. Specifically, the particle size retainer is prepared through the following steps: Hydroxyl-terminated hyperbranched polyester and sulfosuccinic acid were mixed and refluxed at 140℃ under nitrogen protection for 4 hours. After the reaction, the mixture was dried to obtain a particle size maintainer. The hydroxyl-terminated hyperbranched polyester was H101; the molar ratio of the hydroxyl-terminated hyperbranched polyester to sulfosuccinic acid was 1:3.
[0041] The remaining raw materials and preparation process are the same as in Example 1.
[0042] Example 5
[0043] This embodiment provides a method for preparing iron oxide red using iron-containing electroplating waste acid. The difference between this embodiment and Embodiment 1 lies in the preparation process of the particle size retainer. Specifically, the particle size retainer is prepared through the following steps: Hydroxyl-terminated hyperbranched polyester and sulfosuccinic acid were mixed and refluxed at 140℃ under nitrogen protection for 4 hours. After the reaction was completed, the mixture was dried to obtain a particle size maintainer. The hydroxyl-terminated hyperbranched polyester was H1O2; the molar ratio of the hydroxyl-terminated hyperbranched polyester to sulfosuccinic acid was 1:4.
[0044] The remaining raw materials and preparation process are the same as in Example 1.
[0045] Example 6
[0046] This embodiment provides a method for preparing iron oxide red using iron-containing electroplating waste acid. The difference between this embodiment and Embodiment 1 lies in the preparation process of the particle size retainer. Specifically, the particle size retainer is prepared through the following steps: Hydroxyl-terminated hyperbranched polyester and sulfosuccinic acid were mixed and refluxed at 140℃ under nitrogen protection for 4 hours. After the reaction, the mixture was dried to obtain a particle size maintainer. The hydroxyl-terminated hyperbranched polyester was H1O2; the molar ratio of the hydroxyl-terminated hyperbranched polyester to sulfosuccinic acid was 1:5.
[0047] The remaining raw materials and preparation process are the same as in Example 1.
[0048] Example 7
[0049] This embodiment provides a method for preparing iron oxide red using iron-containing electroplating waste acid solution, including the following steps: The first step is to add an excess of elemental iron powder to the acidic iron-containing electroplating waste liquid; then, impurity removal treatment is carried out to remove interfering ions, resulting in a high-content ferrous solution. The acidic iron-containing electroplating waste liquid contains Mn 2+ 0.5 g / L; Cr 3+ 0.8 g / L; Cu 2+ +Zn 2+ + Ni 2+ (Total) 0.2 g / L; The impurity removal agent used to remove interfering ions in the impurity removal treatment is a compound mixture of soluble sulfide and permanganate; the soluble sulfide is sodium sulfide, and the permanganate is potassium permanganate; the ratio of sodium sulfide to acidic iron-containing electroplating waste liquid is 1 g: 1 L; the ratio of permanganate to acidic iron-containing electroplating waste liquid is 3.5 g: 1 L; By controlling the reaction pH to 6.5, temperature to 50℃, and reaction time to 12h, nonionic polyacrylamide, a flocculant, was added. The amount of flocculant added was 0.5% of the mass of the acidic iron-containing electroplating waste liquid. After filtration, a high-ferrous content solution was obtained.
[0050] The second step involves diluting the high-concentration ferrous solution to a ferrous ion concentration of 1 mol / L, neutralizing it with an alkaline precipitant, and then adding a particle size maintainer, which is a hyperbranched surfactant. Air is then introduced for 30 minutes to obtain the precursor slurry. The amount of particle size maintainer added is Fe²⁺. + 5% by mass; the alkaline precipitant is ammonia. The particle size control agent is prepared by the following steps: Hydroxyl-terminated hyperbranched polyester and sulfosuccinic acid were mixed and refluxed at 140℃ under nitrogen protection for 4 hours. After the reaction was completed, the mixture was dried to obtain a particle size maintainer. The hydroxyl-terminated hyperbranched polyester was H101; the molar ratio of the hydroxyl-terminated hyperbranched polyester to sulfosuccinic acid was 1:2.
[0051] The third step involves pressing and washing the precursor slurry to obtain a filter cake. The filter cake is then dispersed in water, and 0.5% (by weight of the filter cake) of nano-sized α-Fe₂O₃ seed crystals are added. After stirring evenly, the mixture is dried. The dried material is then placed in a muffle furnace and calcined using a segmented temperature-controlled method to obtain iron oxide red. The segmented calcination process involves first heating to 400℃ at a rate of 5℃ / min and holding for 2 hours to fully dehydrate the precursor; then heating to 500℃ at a rate of 5℃ / min and holding for 3 hours.
[0052] Comparative Example 1
[0053] The difference between this comparative example and Example 1 is that the particle size retainer is replaced with a terminal hydroxyl hyperbranched polyester, while the other raw materials and preparation process remain the same as in Example 1.
[0054] Comparative Example 2
[0055] The difference between this comparative example and Example 1 is that the particle size retainer is replaced with commercially available dispersant polyvinylpyrrolidone, while the other raw materials and preparation process remain the same as in Example 1.
[0056] Comparative Example 3
[0057] Compared with Comparative Example 2, the segmented calcination conditions of this comparative example are different. First, the temperature is increased to 400℃ at a heating rate of 5℃ / min and held for 2 hours to allow the precursor to be fully dehydrated. Then, the temperature is increased to 800℃ at a heating rate of 5℃ / min and held for 3 hours.
[0058] Performance tests were conducted on Examples 1-7 and Comparative Examples 1-3, and the results are shown in Table 1: Table 1
[0059] As shown in Table 1, combined with Examples 1-7 and Comparative Examples 1-3, the scheme of this invention maintains high calcination efficiency at a relatively low calcination temperature. The strong hydrophilicity and charge repulsion of the sulfonic acid groups in the particle size maintainer enhance dispersion stability. The SO2 generated by the thermal decomposition of the sulfonic acid groups forms a locally reducing micro-atmosphere, inducing Fe... 3+ The reduction and promotion of the crystal transformation from γ-Fe₂O₃ to α-Fe₂O₃ lowers the calcination temperature. During the calcination stage, the introduction of nano-α-Fe₂O₃ seeds provides heterogeneous nucleation sites. Combined with a segmented temperature control process, the dehydration and crystal transformation of the precursor are carried out smoothly, effectively avoiding abnormal grain growth and sintering caused by local overheating. Precise control of the product particle size is achieved, enabling the stable preparation of uniformly distributed nano-iron oxide red with a particle size of 20-40 nm.
[0060] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.
[0061] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A method for preparing iron oxide red using iron-containing electroplating waste acid, characterized in that, Includes the following steps: The first step is to add an iron source to the acidic iron-containing electroplating waste liquid; then, impurity removal treatment is carried out to remove interfering ions, resulting in a high-content ferrous solution. The second step involves diluting the high-content ferrous solution, neutralizing it with an alkaline precipitant, and adding a particle size maintainer, which is a hyperbranched surfactant. Air is then introduced to oxidize the solution and obtain the precursor slurry. The third step involves pressing and washing the precursor slurry to remove chloride and sodium ions, resulting in a filter cake. The filter cake is then dispersed in water, and nano-sized α-Fe2O3 seed crystals are added. After stirring evenly, the mixture is dried and then calcined at a controlled temperature in stages to obtain iron oxide red.
2. The method for preparing iron oxide red using iron-containing electroplating waste acid solution according to claim 1, characterized in that, The hyperbranched surfactant contains sulfonate.
3. The method for preparing iron oxide red using iron-containing electroplating waste acid solution according to claim 1, characterized in that, The particle size control agent is prepared by the following steps: Hydroxyl-terminated hyperbranched polyester and sulfosuccinic acid were mixed and refluxed at 140-145℃ under nitrogen protection for 3-4 hours. After the reaction was completed, the mixture was dried to obtain a particle size retainer. The molar ratio of hydroxyl-terminated hyperbranched polyester to sulfosuccinic acid is 1:2-5.
4. The method for preparing iron oxide red using iron-containing electroplating waste acid solution according to claim 1, characterized in that, The amount of particle size retainer added is Fe² + 1%–5% of the quality.
5. The method for preparing iron oxide red using iron-containing electroplating waste acid solution according to claim 1, characterized in that, The acidic iron-containing electroplating waste liquid includes free acid, ferrous ions, ferric ions, and impurity metal ions.
6. The method for preparing iron oxide red using iron-containing electroplating waste acid solution according to claim 1, characterized in that, The impurity removal agent used to remove interfering ions in the impurity removal treatment is a mixture of soluble sulfide and permanganate; By controlling the reaction pH to 5.0-6.5, temperature to 40-60℃, and reaction time to 1-2 hours, and by continuing to add flocculant, the amount of flocculant added is 0.5%-2% of the mass of the acidic iron-containing electroplating waste liquid, and filtering to obtain a high-ferrous content solution.
7. The method for preparing iron oxide red using iron-containing electroplating waste acid solution according to claim 1, characterized in that, The soluble sulfide is sodium sulfide, and the permanganate is potassium permanganate; the mass ratio of soluble sulfide to permanganate is 2.5-4:
1.
8. The method for preparing iron oxide red using iron-containing electroplating waste acid solution according to claim 1, characterized in that, The alkaline precipitant is one of ammonia, sodium hydroxide solution, and ammonium carbonate solution.
9. A method for preparing iron oxide red using iron-containing electroplating waste acid solution according to claim 1, characterized in that, Segmented calcination: First, heat to 300-400℃ at a heating rate of 2-5℃ / min and hold for 1-2 hours; then heat to 500-600℃ at a heating rate of 5-10℃ / min and hold for 2-3 hours.
10. A method for preparing iron oxide red using iron-containing electroplating waste acid solution according to claim 1, characterized in that, The iron source is elemental iron powder or iron oxide.