Material treatment method for synchronously recycling acid and iron ions in acid mud

Abstract

The invention discloses a material treatment method for synchronously recycling acid and iron ions in acid mud, belongs to the technical field of solid waste treatment, and is used for solving the technical problem that in the prior art, acid and iron ions in acid mud are difficult to efficiently separate and recycle. The recycled iron oxide is obtained. The method comprises the following steps: synthesizing a cationic flocculant and pretreated silica fume, adding the pretreated silica fume and the cationic flocculant into acid mud diluted slurry to coagulate and settle impurities and metal ions, carrying out suction filtration to obtain filtrate and fluorine-containing silicon filter residues, and carrying out extraction and reverse extraction on the filtrate by using an organic extraction agent to realize efficient separation of acid and metal ions. The method comprises the following steps: recycling acid sludge to obtain recycled acid liquor, adjusting the pH value, carrying out fractional precipitation and calcining metal ions to prepare high-purity recycled iron oxide, and realizing synergistic and efficient recycling of acid and iron ions in the acid sludge.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid waste treatment, in particular to a material treatment method for synchronous recovery and utilization of acid and iron ions in acid sludge. BACKGROUND

[0002] Silicon powder production enterprises will produce a large amount of high-acidity acid sludge in the process of silicon block crushing, pickling and impurity removal and post-treatment, which contains free acid, iron ions and various inorganic impurities such as silicon, aluminum, calcium and fluorine, and has strong corrosive and high suspended solid content characteristics. With the expansion of the silicon material industry, the harmless and resourceful treatment of acid sludge has gradually become the focus of the industry, and the synchronous recovery and utilization technology of acid and iron ions in acid sludge has been continuously developed.

[0003] At present, common treatment methods include inorganic adsorption separation method, alkali precipitation method, membrane separation method, ion exchange method, etc., and the materials used for acid sludge treatment include activated diatomite, activated alumina, supported metal oxide adsorbent, strong acid cation exchange resin and porous carbon material, and common modification technologies include acid-base activation, surface functional group grafting, metal ion or metal oxide loading, interfacial compatibilizer treatment and plasma enhanced modification, etc., in order to improve the acid resistance, specific surface area and selective adsorption or separation capacity of the material for iron ions or acid components.

[0004] Although the existing materials and modification methods have been applied in acid sludge treatment, there are still significant deficiencies in dealing with the high-acidity, high-colloid content and fluorine-containing silicon material complex system of silicon powder enterprise acid sludge: For example, inorganic adsorption materials are prone to structural erosion or surface activity decline in a strong acid environment, resulting in low adsorption capacity and difficulty in simultaneously enriching iron ions and recovering acid liquid, ion exchange resins are prone to pore blockage and functional group deactivation in a system containing a large amount of silicon, fluorine and metal impurities, and have poor recycling performance; Membrane separation technology is easily contaminated by silicon colloid deposition and metal hydroxide condensation, has high operating cost, and although conventional surface modification methods can improve the activity of the material, they are insufficient in strong acid resistance and are prone to interface reaction with silicon and fluorine species in acid sludge, resulting in unstable separation selectivity.

[0005] These deficiencies are mainly due to the complex composition, high solid content, wide colloid particle size distribution and strong corrosiveness of silicon powder acid sludge, as well as the multiple interface interference between different metal ions and silicon-fluorine complexes, which makes it difficult for traditional materials to achieve efficient and stable synchronous recovery of acid and iron ions. Therefore, a solution is proposed. SUMMARY

[0006] The present application aims to provide a material treatment method for synchronous recovery and utilization of acid and iron ions in acid sludge, which solves the technical problem of inefficient separation and recovery of acid and iron ions in acid sludge in the prior art.

[0007] The object of the present application can be achieved by the following technical solution: a material processing method for synchronous recovery of acid and iron ions in acid sludge, comprising the following steps: S1, deionized water is placed in a reaction kettle, acid sludge is added, stirred at room temperature for 15-30 min, and acid sludge dilution slurry is obtained; S2, the acid sludge dilution slurry is placed in a reaction kettle, pretreated silica ash is added, stirred at room temperature for 15-30 min, cationic coagulant is added, and filtration is performed, to obtain filtrate and fluorine-containing silicon filter residue; The preparation reaction principle of the filtrate and the fluorine-containing silicon filter residue is: In step S1, the acid sludge is mixed with deionized water to form a dilution slurry, which reduces the viscosity of the system and promotes the dispersion of suspended particles and dissolved components, providing a uniform reaction environment for subsequent reactions. In step S2, the pretreated silica ash has a high specific surface area and abundant active Si-OH groups. At the same time, the addition of cationic coagulant promotes the rapid aggregation and sedimentation of negatively charged colloidal particles in the acid sludge through electrostatic adsorption and molecular chain bridging. Fluoride ions react with active silicon dioxide to form fluorine-containing silicate precipitates. The synergistic effect of the two enables effective separation of acidic components and iron ions in the acid sludge system, generating fluorine-containing silicon filter residue and clear filtrate.

[0008] S3, the filtrate is added to a separatory funnel, organic extraction liquid is added, and washing and extraction are performed 2-4 times, and post-treatment is performed to obtain recycled acid liquid and metal-containing aqueous solution; The preparation reaction principle of the recycled acid liquid and the metal-containing aqueous solution is: During the reaction, the filtrate is fully contacted with the organic extraction liquid composed of 1-decanol, trioctylamine, and kerosene in the separatory funnel. Through the principle of liquid-liquid extraction, the acid components and metal ions are separated. Trioctylamine is a strong organic phase tertiary amine that can form an ion pair complex with inorganic acids in the filtrate, which is soluble in the organic phase, thereby transferring the acid from the aqueous phase to the organic phase. 1-decanol acts as a cosolvent and an interfacial activity regulator, improving the compatibility and mass transfer efficiency of the extraction system. Kerosene acts as a diluent, providing an inert organic phase medium, reducing the viscosity of the extraction system, and stabilizing the phase structure. After 2-4 extractions, the acid components mainly enter the organic phase and can be recycled through back extraction, while the metal ions are enriched in the aqueous phase, forming a metal-containing aqueous solution, achieving effective separation and synchronous recovery of acid and iron ions.

[0009] S4, the metal-containing aqueous solution is adjusted to be alkaline and deacidified to obtain recycled iron oxide; In step S2, the cationic flocculant is prepared by stirring diallyl dimethyl ammonium chloride, OP-10 and deionized water in a reaction kettle under nitrogen atmosphere protection, adding lauryl methacrylate, heating the reaction kettle to 45-55℃, adding azobisdimethylaminoformamide hydrochloride, and keeping the reaction at 60-70℃ for 4-6 hours, and then post-treating to obtain the cationic flocculant.

[0010] The preparation reaction principle of the cationic flocculant is as follows: During the reaction, diallyl dimethyl ammonium chloride acts as a positively charged monomer, lauryl methacrylate acts as a long-chain alkyl-containing hydrophobic monomer, and non-ionic surfactant OP-10 plays a role in dispersion and emulsification to ensure the stability of the reaction system. After heating to 45-55℃, the initiator azobisdimethylaminoformamide hydrochloride is added, which decomposes to generate free radicals at 60-70℃, initiating chain copolymerization between diallyl dimethyl ammonium chloride and lauryl methacrylate, forming a cationic flocculant with both cationic charge centers and hydrophobic alkyl side chains.

[0011] Further, in step S1, the ratio of deionized water to acid sludge is 8-10g:20-40mL; in step S2, the weight ratio of acid sludge dilution slurry, pretreated silica ash and cationic flocculant is 15-20g:0.5-1g:0.01-0.02g; in step S3, the organic extraction liquid is composed of 1-decanol, trioctylamine and kerosene in a volume ratio of 2-3:15-18:70-75; the post-treatment step includes: after washing and extraction are completed, standing and separating into layers to obtain organic phase and metal-containing aqueous solution, washing the organic phase with saturated brine 2-4 times, back-extracting with deionized water, and heating and concentrating the acid-containing aqueous phase to obtain recycled acid.

[0012] Further, the preparation method of the pretreated silica ash is as follows: adding silica ash into a tubular furnace, calcining at high temperature for 1-2 hours in air atmosphere, and post-treating to obtain pretreated silica ash.

[0013] The preparation reaction principle of the pretreated silica ash is as follows: During the reaction, silica ash is placed in a tubular furnace in an air atmosphere and calcined at high temperature. Silica ash is mainly composed of amorphous silica particles and a small amount of carbon and metal oxide impurities. In an air environment at 500-700℃, residual carbon, volatile organic compounds and adsorbed water are oxidized and removed, and part of the surface hydroxyl groups are dehydrated and condensed to form a more stable and larger specific surface area active silica surface. After this treatment, the silica ash particle surface is clean, the structure is loose, the reaction sites are increased, and the surface energy is improved, which can enhance the adsorption and reaction capacity of the silica ash with metal ions, fluoride ions and other components in the acid sludge, thereby obtaining pretreated silica ash with higher chemical activity.

[0014] Further, the high-temperature calcination temperature is 500-700℃, the heating rate is 5-10℃ / min, and the post-processing step includes: after the reaction is completed, the product is ground through a 200-mesh sieve after being cooled to room temperature, to obtain the pretreated silica ash.

[0015] Further, the ratio of the use amounts of the diallyldimethyl ammonium chloride, OP-10, deionized water, lauryl methacrylate, and azobisdimethylvaleronitrile hydrochloride is 2-4 g:0.05-0.10 g:20-30 mL:0.05-0.10 g:0.02-0.03 g, and the post-processing step includes: after the reaction is completed, the reaction solution is cooled to room temperature, and then is added into ethanol to precipitate and separate out, is suction-filtered, and the filter cake is washed with ethanol for 2-4 times, and is transferred to an oven with a temperature of 50-60℃, and is dried to constant weight, to obtain the cationic coagulant.

[0016] Further, in step S4, the recycled iron oxide is prepared by the following steps: A1, the metal-containing aqueous solution is placed in a reaction kettle, sodium hydroxide solution is added, the pH is adjusted to 5-6, and stirring is performed at room temperature for 15-30 min, and the metal hydroxide is obtained by post-processing; A2, the metal hydroxide is placed in a reaction kettle, sodium hydroxide solution is added, the pH is adjusted to 10-14, and stirring is performed at room temperature for 15-30 min, and the recycled iron hydroxide is obtained by post-processing; A3, the recycled iron hydroxide is added into a tubular furnace, and is calcined at high temperature for 1-3 h in an air atmosphere, and the recycled iron oxide is obtained by post-processing.

[0017] The reaction principle for preparing the recycled iron oxide is as follows: In step A1, sodium hydroxide solution is added to the metal-containing aqueous solution, and the pH is adjusted to 5-6, so that the metal ions such as iron and aluminum in the solution gradually undergo hydrolysis and precipitation reaction to form corresponding metal hydroxide precipitate, thereby realizing the preliminary separation and enrichment of the metal components. In step A2, the pH is continuously increased to 10-14, which can further promote the complete precipitation of ferric ions to form iron hydroxide, effectively remove impurity ions, and improve the purity of the precipitate. Finally, in step A3, the obtained iron hydroxide is calcined at high temperature for 1-3 h in an air atmosphere, to undergo dehydration and oxidation reaction, and generate stable hematite-type iron oxide solid product, thereby obtaining the recycled iron oxide.

[0018] Further, in step A1, the concentration of the sodium hydroxide solution is 0.01-0.03 wt%, and the post-processing steps include: after the reaction is completed, filtration is performed, the filter cake is washed 2-4 times with deionized water, transferred to an oven at 50-60℃, and dried to constant weight to obtain metal hydroxide; in step A2, the concentration of the sodium hydroxide solution is 0.01-0.03 wt%, and the post-processing steps include: after the reaction is completed, filtration is performed, the filter cake is washed 2-4 times with deionized water, transferred to an oven at 50-60℃, and dried to constant weight to obtain reclaimed ferric hydroxide; in step A3, the high-temperature calcination temperature is 450-650℃, the heating rate is 2-5℃ / min, and the post-processing steps include: after the reaction is completed, the product is allowed to return to room temperature, ground, and passed through a 200-mesh sieve to obtain reclaimed ferric oxide.

[0019] The present invention has the following beneficial effects: This invention utilizes pretreated silica fume to induce sedimentation and adsorption in diluted acid sludge slurry. Firstly, the pretreated silica fume undergoes high-temperature calcination, enhancing its surface activity and adsorption properties. This allows it to adsorb fluoride ions from the acid sludge and form fluorinated silicate precipitates when mixed with the diluted sludge. The addition of silica fume promotes the separation of acid and metal from the acid sludge, improving acid recovery efficiency. During subsequent filtration, the pretreated silica fume forms coagulants, aiding in the removal of impurities from the aqueous solution and thus increasing the purity of the recovered acid. Secondly, the high-temperature calcination pretreatment of the silica fume enhances its performance in acidic environments. The stability of silica fume allows it to maintain good performance during acid sludge treatment, avoiding the impact of acidic environment on material corrosion. Through this treatment, the specific surface area and porosity of silica fume are improved, enabling it to more efficiently adsorb and remove harmful components in acid sludge, thereby reducing the interference of metal ions on the subsequent iron oxide recovery process. With the addition of silica fume, iron ions can be separated more efficiently in the subsequent extraction and precipitation processes, reducing the impact of impurities, ensuring the quality of iron oxide, avoiding the damage of impurities to the iron oxide structure during high-temperature calcination, and further improving the purity of the recovered iron oxide.

[0020] This invention prepares a cationic coagulant through free radical polymerization of positively charged and hydrophobic monomers. Firstly, the cationic coagulant, due to its cationic nature, interacts with negatively charged substances in acid sludge, promoting the coagulation and precipitation of iron ions and other contaminants. In this way, the coagulant effectively separates iron ions from the acid sludge, reducing interference from iron ions in subsequent acid recovery and improving the purity of the acid solution. This coagulation helps separate silicate and fluoride impurities from the acid solution, effectively improving the purity of the recycled acid solution and ensuring the stability of acidity and recovery rate. Secondly, the addition of the cationic coagulant helps improve the treatment process of diluted acid sludge, ensuring that the coagulated precipitate can be separated from the solution more quickly and thoroughly in the subsequent filtration stage. This not only improves the acid recovery efficiency but also reduces the complexity of subsequent filtration and cleaning. Finally, the calcined iron oxide possesses good quality and is suitable for high-end applications such as catalysis and pigments.

[0021] This invention relates to an organic extractant prepared by mixing 1-decyl alcohol, trioctylamine, and kerosene in a specific ratio. Firstly, the organic extractant exhibits excellent selective extraction performance. Trioctylamine can form stable and reversible complexes with acidic components, while 1-decyl alcohol, acting as a solubilizer, improves the system's compatibility and mass transfer efficiency. Kerosene, as a diluent, effectively regulates the extraction equilibrium, thereby achieving efficient separation of acids and metal ions. This system can separate acids from metallic impurities such as iron ions in acid sludge filtrate, allowing the acid to enter the organic phase and then recover it to the aqueous phase through a back-extraction process, thus obtaining high-purity acid. The process of recycling acid reduces interference from metal impurities, improves acid recovery rate and reuse value, and the use of organic extractants concentrates the concentration of metal ions in the metal-containing aqueous solution, which is conducive to the complete precipitation of iron ions in the subsequent hydroxide reaction, thus producing metal hydroxide with low impurity content. Finally, high-purity recycled iron oxide is obtained by calcination. Therefore, the introduction of organic extractants not only improves the separation efficiency of acid and metal ions, but also optimizes the purity and stability of the recycled product, achieving simultaneous and efficient recovery of acid and iron ions, which has significant technical and environmental advantages. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The acid sludge used in this invention was purchased from Ansteel Industry Micro-aluminum Powder Co., Ltd., with a pH of 0.5-2.0. The kerosene used in this invention is purchased from Kunshan Anwen Chemical Co., Ltd., with the model number: HT and the brand: paratherm Bosch; The silica fume used in this invention is purchased from Angang Industry Fine Aluminum Powder Co., Ltd., with the particle size: 0.05 - 0.3μm; The OP - 10 used in this invention is purchased from Yixing Jianteng Chemical Co., Ltd., with the product name: octylphenol polyoxyethylene ether and the density: 0.984 g / cm 3 ; Example 1: This example provides a preparation method for the material treatment method of synchronous recovery and utilization of acid and iron ions in acid sludge, including the following steps: Step S1, prepare a cationic coagulant; Weigh: 20 g of diallyldimethylammonium chloride, 0.5 g of OP - 10 and 200 mL of deionized water, place them in a reaction kettle protected by nitrogen atmosphere and stir. Add 0.5 g of lauryl methacrylate, raise the temperature of the reaction kettle to 45°C, add 0.2 g of azobisisobutyramidine hydrochloride, keep the temperature at 60°C for the reaction, keep the temperature for 4 h. After the reaction is completed, wait for the reaction solution to cool to room temperature, add the reaction solution to ethanol for precipitation, filter by suction, wash the filter cake with ethanol twice, transfer it to an oven at 50°C, and dry it to constant weight to obtain the cationic coagulant.

[0024] Step S2, prepare pretreated silica fume; Add silica fume into a tubular furnace, under air atmosphere, raise the temperature to 500°C at a heating rate of 5°C / min, calcine at high temperature for 1 h. After the reaction is completed, wait for the product to return to room temperature, grind the product through a 200 - mesh sieve to obtain pretreated silica fume.

[0025] Step S3, prepare recycled acid solution and metal - containing aqueous solution; Weigh: 80 g of deionized water and place it in a reaction kettle, add 200 mL of acid sludge, stir at room temperature for 15 min to obtain acid sludge dilution slurry; Weigh: 150 g of acid sludge dilution slurry and place it in a reaction kettle, add 5 g of pretreated silica fume, stir at room temperature for 15 min, add 0.1 g of cationic coagulant, filter by suction to obtain filtrate and fluorosilicate filter residue.

[0026] Step S4, prepare recycled iron oxide; Mix 1 - decanol, trioctylamine and kerosene evenly according to the volume ratio of 2:15:70 to obtain an organic extraction solution for standby; Place the filtrate in a separatory funnel, add organic extractant at 0.5 times the volume of the filtrate, shake and mix thoroughly at room temperature, wash and extract twice, let stand to separate the layers, separate the liquid to obtain the organic phase and the metal-containing aqueous solution, wash the organic phase twice with saturated brine, back-extract with deionized water, heat and concentrate the acid-containing aqueous phase to obtain the recycled acid solution. Weigh: Place the metal-containing aqueous solution in a reaction vessel, add 0.01wt% sodium hydroxide solution, adjust the pH to 5, stir at room temperature for 15 min, after the reaction is complete, filter, wash the filter cake twice with deionized water, transfer it to an oven at 50℃, and dry to constant weight to obtain metal hydroxide; Weigh out: place the metal hydroxide in a reaction vessel, add 0.01wt% sodium hydroxide solution, adjust the pH to 10, stir at room temperature for 15 min, after the reaction is complete, filter, wash the filter cake twice with deionized water, transfer it to an oven at 50℃, dry to constant weight, and obtain recycled iron hydroxide. Recycled ferric hydroxide was added to a tube furnace and heated to 450°C at a rate of 2°C / min under air atmosphere. The mixture was then calcined at high temperature for 1 hour. After the reaction was completed, the product was allowed to return to room temperature, ground, and passed through a 200-mesh sieve to obtain recycled ferric oxide.

[0027] Example 2: This embodiment provides a method for preparing a material treatment method for the simultaneous recovery and utilization of acid and iron ions from acidic sludge, comprising the following steps: Step S1: Prepare a cationic coagulant; Weigh out 30g of diallyl dimethyl ammonium chloride, 0.75g of OP-10 and 250mL of deionized water and place them in a nitrogen-protected reactor. Stir the mixture and add 0.75g of lauryl methacrylate. Heat the reactor to 50℃ and add 0.25g of azobisisobutyramidine hydrochloride. Maintain the reaction temperature at 65℃ for 5 hours. After the reaction is complete, wait for the reaction solution to cool to room temperature. Add ethanol to the reaction solution to precipitate the precipitate. Filter the precipitate and wash it three times with ethanol. Transfer the precipitate to an oven at 55℃ and dry it to constant weight to obtain the cationic coagulant.

[0028] Step S2: Prepare pretreated silica fume; Silica fume was added to a tube furnace and heated to 600°C at a rate of 7°C / min in air atmosphere. The furnace was then calcined at high temperature for 1.5 hours. After the reaction was completed, the product was allowed to return to room temperature and then ground through a 200-mesh sieve to obtain pretreated silica fume.

[0029] Step S3: Prepare the reclaimed acid solution and the metal-containing aqueous solution; Weigh out 90g of deionized water and place it in a reaction vessel. Add 300mL of acid mud and stir at room temperature for 20 minutes to obtain diluted acid mud slurry. Weigh out 175g of diluted acid mud slurry and place it in a reactor. Add 7.5g of pretreated silica fume, stir at room temperature for 20 minutes, add 0.15g of cationic coagulant, filter, and obtain filtrate and fluorinated silica filter residue.

[0030] Step S4: Prepare recycled iron oxide; 1-Decanol, trioctylamine, and kerosene were mixed evenly at a volume ratio of 2.5:16.5:72.5 to obtain an organic extract for later use. Place the filtrate in a separatory funnel, add an organic extractant at a volume equal to that of the filtrate, mix thoroughly by shaking at room temperature, wash and extract three times, allow to stand to separate into layers, separate the liquid to obtain an organic phase and a metal-containing aqueous solution, wash the organic phase three times with saturated brine, back-extract with deionized water, and heat and concentrate the acid-containing aqueous phase to obtain a recycled acid solution. Weigh out: place the metal-containing aqueous solution in a reaction vessel, add 0.02wt% sodium hydroxide solution, adjust the pH to 5.5, stir at room temperature for 20 min, after the reaction is complete, filter, wash the filter cake 3 times with deionized water, transfer it to an oven at 55℃, and dry to constant weight to obtain metal hydroxide; Weigh out: place the metal hydroxide in a reaction vessel, add 0.02wt% sodium hydroxide solution, adjust the pH to 12, stir at room temperature for 20 min, after the reaction is complete, filter, wash the filter cake 3 times with deionized water, transfer it to an oven at 55℃, dry to constant weight, and obtain recycled iron hydroxide; Recycled ferric hydroxide was added to a tube furnace and heated to 600°C at a rate of 3°C / min in air atmosphere. The mixture was then calcined at high temperature for 2 hours. After the reaction was completed, the product was allowed to return to room temperature, ground, and passed through a 200-mesh sieve to obtain recycled ferric oxide.

[0031] Example 3: This embodiment provides a method for preparing a material treatment method for the simultaneous recovery and utilization of acid and iron ions from acidic sludge, comprising the following steps: Step S1: Prepare a cationic coagulant; Weigh 40g diallyl dimethyl ammonium chloride, 1g OP-10 and 300mL deionized water and place them in a nitrogen-protected reactor and stir. Add 1g lauryl methacrylate and heat the reactor to 55℃. Add 0.3g azobisisobutyramidine hydrochloride and maintain the temperature at 70℃ for 6 hours. After the reaction is complete, wait for the reaction solution to cool to room temperature, add ethanol to precipitate the precipitate, filter, wash the filter cake with ethanol 4 times, transfer it to an oven at 60℃ and dry it to constant weight to obtain the cationic coagulant.

[0032] Step S2: Prepare pretreated silica fume; Silica fume was added to a tube furnace and heated to 700°C at a rate of 10°C / min in an air atmosphere. The furnace was then calcined at high temperature for 2 hours. After the reaction was completed, the product was allowed to return to room temperature and then ground through a 200-mesh sieve to obtain pretreated silica fume.

[0033] Step S3: Prepare the reclaimed acid solution and the metal-containing aqueous solution; Weigh 100g of deionized water and place it in a reaction vessel. Add 400mL of acid mud and stir at room temperature for 30 minutes to obtain diluted acid mud slurry. Weigh 200g of diluted acid mud slurry and place it in a reaction vessel. Add 10g of pretreated silica fume, stir at room temperature for 30min, add 0.2g of cationic coagulant, filter, and obtain filtrate and fluorinated silica filter residue.

[0034] Step S4: Prepare recycled iron oxide; 1-Decanol, trioctylamine and kerosene were mixed evenly at a volume ratio of 3:18:75 to obtain an organic extract, which was then set aside. Place the filtrate in a separatory funnel, add an organic extractant at a volume equal to that of the filtrate, mix thoroughly by shaking at room temperature, wash and extract 4 times, allow to stand and separate into layers, separate to obtain an organic phase and a metal-containing aqueous solution, wash the organic phase 4 times with saturated brine, back-extract with deionized water, heat and concentrate the acid-containing aqueous phase to obtain a recycled acid solution. Weigh: Place the metal-containing aqueous solution in a reaction vessel, add 0.03wt% sodium hydroxide solution, adjust the pH to 6, stir at room temperature for 30 min, after the reaction is complete, filter, wash the filter cake 4 times with deionized water, transfer it to an oven at 60℃, and dry to constant weight to obtain metal hydroxide; Weigh out: place the metal hydroxide in a reaction vessel, add 0.03wt% sodium hydroxide solution, adjust the pH to 14, stir at room temperature for 30 min, after the reaction is complete, filter, wash the filter cake 4 times with deionized water, transfer it to an oven at 60℃, dry to constant weight, and obtain recycled iron hydroxide; Recycled ferric hydroxide was added to a tube furnace and heated to 650°C at a rate of 5°C / min in air atmosphere. The mixture was then calcined at high temperature for 3 hours. After the reaction was completed, the product was allowed to return to room temperature, ground, and passed through a 200-mesh sieve to obtain recycled ferric oxide.

[0035] Comparative Example 1: The difference between this comparative example and Examples 1-3 is that the use of pretreated silica fume was omitted when preparing the filtrate and the fluorinated silica filter residue.

[0036] Comparative Example 2: The difference between this comparative example and Examples 1-3 is that the cationic coagulant was omitted when preparing the filtrate and the fluorinated silica filter residue.

[0037] Comparative Example 3: The difference between this comparative example and Examples 1-3 is that, in the preparation of recycled iron oxide, an equal amount of metal hydroxide is used instead of recycled iron hydroxide.

[0038] Performance testing: The mass fraction of iron oxide in the recovered iron oxide samples in Examples 1-3 and Comparative Examples 1-3 was tested according to the standard GB / T 18114.7-2010 "Chemical Analysis Methods for Rare Earth Concentrates - Part 7: Determination of Iron Oxide Content by Potassium Dichromate Titration Method", and the purity and recovery rate of the recovered iron oxide were calculated. Take 50 mL of recycled acid solution and place it in a beaker. Insert the pH meter electrode into the acid sample and stir gently to ensure uniform contact. Observe and record the stable reading of the pH meter. Record the pH value only after the reading is stable. After each measurement, rinse the electrode thoroughly with deionized water. Take 50 mL of the recycled acid solution and 3 drops of phenolphthalein indicator and place them in a beaker. Titrate with 0.1 mol / L sodium hydroxide aqueous solution until the solution changes from colorless to light pink and remains so for more than 30 seconds. Record the volume of sodium hydroxide aqueous solution used at this point. Then, according to the formula... Calculate the concentration of the recycled acid solution, where This indicates the concentration and volume of the recycled acid solution. Indicates the concentration and volume of an aqueous sodium hydroxide solution; The specific test results are shown in Table 1 below.

[0039] Table 1 - Performance test data of the samples: Data Analysis: Comparative analysis of the data in Table 1 above shows that the purity of the recovered iron oxide prepared by this invention is 99.5%, the recovery rate is 86.3%, and the concentration of the recovered acid solution is 2.6 mol·L⁻¹. -1 The pH value was 1.3, and all data were better than the comparative example; This invention first synthesizes a cationic coagulant and pre-treats silica fume. Then, acid sludge is mixed with deionized water to form a diluted acid sludge slurry. Pre-treated silica fume and cationic coagulant are added to cause impurities and metal ions to coagulate and settle. After filtration, filtrate and fluorinated silica residue are obtained. Subsequently, the filtrate is extracted and back-extracted using an organic extractant composed of 1-decyl alcohol, trioctylamine, and kerosene to achieve efficient separation of acid and metal ions, obtaining a reclaimed acid solution. Then, by adjusting the pH, the metal ions are precipitated in steps and calcined to obtain high-purity reclaimed iron oxide. This method achieves synergistic and efficient recovery of acid and iron ions. The obtained acid solution has high purity and stable pH, and the iron oxide purity can reach over 98%, which has good resource utilization and environmental benefits.

[0040] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A material processing method for simultaneous recovery of acid and iron ions from acid sludge, characterized by, The method comprises the following steps: S1, placing deionized water in a reaction kettle, adding acid sludge, stirring at room temperature for 15-30 min, and obtaining acid sludge dilution slurry; S2, placing the acid sludge dilution slurry in the reaction kettle, adding pretreated silica ash, stirring at room temperature for 15-30 min, adding a cationic coagulant, and filtering to obtain filtrate and fluorine-containing silica filter residue; S3, adding the filtrate to a separatory funnel, adding organic extraction liquid, washing and extracting 2-4 times, and post-treating to obtain recycled acid liquid and metal-containing aqueous solution; S4, adjusting the pH of the metal-containing aqueous solution, removing acid, and obtaining recycled iron oxide; In step S2, the cationic coagulant is prepared by placing diallyl dimethyl ammonium chloride, OP-10 and deionized water in a reaction kettle under nitrogen atmosphere protection, stirring, adding lauryl methacrylate, heating the reaction kettle to 45-55℃, adding azobisdimethylaminoformamide hydrochloride, and reacting at 60-70℃ for 4-6 h, and post-treating to obtain the cationic coagulant.

2. The material treatment method for simultaneously recovering acid and iron ions from acid sludge according to claim 1, characterized by, In step S1, the amount ratio of deionized water to acid sludge is 8-10 g:20-40 mL; in step S2, the weight ratio of acid sludge dilution slurry, pretreated silica ash and cationic coagulant is 15-20 g:0.5-1 g:0.01-0.02 g; in step S3, the organic extraction liquid is composed of 1-decanol, trioctylamine and kerosene in a volume ratio of 2-3:15-18:70-75.

3. The material treatment method for simultaneously recovering acid and iron ions from acid sludge according to claim 1, characterized by, The pretreated silica ash is prepared by adding silica ash into a tubular furnace, calcining at high temperature for 1-2 h under air atmosphere, and post-treating to obtain the pretreated silica ash.

4. The material treatment method for simultaneously recovering acid and iron ions from acid sludge according to claim 3, characterized by, The temperature of the high-temperature calcination is 500-700℃, and the heating rate is 5-10℃ / min.

5. The material processing method for simultaneous recovery of acid and iron ions from acid sludge according to claim 1, characterized in that, The amount ratio of diallyl dimethyl ammonium chloride, OP-10, deionized water, lauryl methacrylate and azobisdimethylaminoformamide hydrochloride is 2-4 g:0.05-0.10 g:20-30 mL:0.05-0.10 g:0.02-0.03 g.

6. The material processing method for simultaneous recovery of acid and iron ions from acid sludge according to claim 1, characterized in that, In step S4, the recycled iron oxide is prepared by the following steps: A1, placing the metal-containing aqueous solution in a reaction kettle, adding sodium hydroxide solution, adjusting the pH to 5-6, stirring at room temperature for 15-30 min, and post-treating to obtain metal hydroxide; A2, placing the metal hydroxide in a reaction kettle, adding sodium hydroxide solution, adjusting the pH to 10-14, stirring at room temperature for 15-30 min, and post-treating to obtain recycled iron hydroxide; A3, adding the recycled iron hydroxide into a tubular furnace, calcining at high temperature for 1-3 h under air atmosphere, and post-treating to obtain the recycled iron oxide.

7. The material treatment method for simultaneously recovering acid and iron ions from acid sludge according to claim 6, characterized by, In step A1, the concentration of the sodium hydroxide solution is 0.01-0.03wt%; in step A2, the concentration of the sodium hydroxide solution is 0.01-0.03wt%; in step A3, the temperature of the high-temperature calcination is 450-650℃, and the heating rate is 2-5℃ / min.

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