A material treatment method for simultaneous recovery and utilization of acid and iron ions from acidic sludge.

Abstract

This invention discloses a material treatment method for the simultaneous recovery and utilization of acid and iron ions from acid sludge, belonging to the field of solid waste treatment technology. It addresses the technical problem of the difficulty in efficiently separating and recovering acid and iron ions from acid sludge in existing technologies. Specifically, it includes the following steps: adjusting the alkali content of a metal-containing aqueous solution to remove acid, thereby obtaining recyclable iron oxide. This invention utilizes a synthesized cationic coagulant and pretreated silica fume. These are added to the diluted acid sludge slurry, causing impurities and metal ions to coagulate and settle. After filtration, a filtrate and a fluorinated silica fume are obtained. The filtrate is then extracted and back-extracted using an organic extractant to achieve efficient separation of acid and metal ions, obtaining a recyclable acid solution. The metal ions are then treated by adjusting the pH stepwise precipitation and calcination to obtain high-purity recyclable iron oxide, achieving the synergistic and efficient recovery of acid and iron ions from acid sludge.

Description

Technical Field

[0001] This invention relates to the field of solid waste treatment technology, specifically to a material treatment method for the simultaneous recovery and utilization of acid and iron ions from acid sludge. Background Technology

[0002] Silicon powder manufacturers generate a large amount of highly acidic sludge during silicon block crushing, acid washing and impurity removal and post-processing. This sludge contains free acid, iron ions and various inorganic impurities such as silicon, aluminum, calcium and fluorine, exhibiting strong corrosiveness and high suspended solids content. As the silicon material industry expands, the harmless and resource-based treatment of sludge has gradually become an industry focus, and the technology for the simultaneous recovery and utilization of acid and iron ions in sludge has been continuously developed.

[0003] Currently, common treatment methods include inorganic adsorption separation, alkaline precipitation, membrane separation, and ion exchange. Materials used for acid sludge treatment include activated diatomaceous earth, activated alumina, supported metal oxide adsorbents, strong acid cation exchange resins, and porous carbon materials. Common modification techniques include acid-base activation, surface functional group grafting, metal ion or metal oxide loading, interface compatibilizer treatment, and plasma-enhanced modification to improve the acid resistance, specific surface area, and selective adsorption or separation capacity of iron ions or acid components.

[0004] Although existing materials and modification methods have been applied in acid sludge treatment, they still have significant shortcomings when dealing with the complex system of acid sludge from silicon powder enterprises, which is characterized by high acidity, high colloidal content, and fluorine-containing silicon substances.

[0005] For example, inorganic adsorbent materials are easily eroded or have reduced surface activity in strong acid environments, resulting in low adsorption capacity and difficulty in simultaneously achieving iron ion enrichment and acid recovery. Ion exchange resins are prone to pore blockage and functional group deactivation in systems containing large amounts of silicon, fluorine and metal impurities, resulting in poor recyclability.

[0006] Membrane separation technology is easily contaminated by silica gel deposition and metal hydroxide aggregation, resulting in high operating costs. Although conventional surface modification methods can improve material activity, they are not resistant to strong acids and are prone to interfacial reactions with silicon and fluorine species in acidic sludge, leading to unstable separation selectivity.

[0007] These shortcomings mainly stem from the complex composition, high solid content, wide colloidal particle size distribution, and strong corrosiveness of silica powder acid mud, as well as the easy occurrence of multiple interfacial interferences between different metal ions and silicon-fluorine complexes, making it difficult for traditional materials to achieve efficient and stable synchronous recovery of acid and iron ions. Therefore, a solution is proposed. Summary of the Invention

[0008] The purpose of this invention is to provide a material processing method for the simultaneous recovery and utilization of acid and iron ions in acid sludge, which solves the technical problem of the difficulty in efficiently separating and recovering acid and iron ions in acid sludge in the prior art.

[0009] The objective of this invention can be achieved through the following technical solution: a material treatment method for the simultaneous recovery and utilization of acid and iron ions from acid sludge, comprising the following steps:

[0010] S1. Place deionized water in a reactor, add acid mud, and stir at room temperature for 15-30 minutes to obtain diluted acid mud slurry.

[0011] S2. Place the diluted acid mud slurry in a reactor, add pretreated silica fume, stir at room temperature for 15-30 minutes, add cationic coagulant, filter, and obtain filtrate and fluorinated silica filter residue.

[0012] The reaction principle for preparing the filtrate and fluorosilicone filter residue is as follows:

[0013] In step S1, acid sludge is mixed with deionized water to form a diluted slurry, which reduces the viscosity of the system and promotes the full dispersion of suspended particles and dissolved components, providing a uniform reaction environment for subsequent reactions. In step S2, the pretreated silica fume added has a high specific surface area and abundant active Si-OH groups. At the same time, the added cationic coagulant further 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 silica to form fluorinated silicate precipitates. The two work synergistically to effectively separate the acidic components and iron ions in the acid sludge system, generating fluorinated silica filter residue and clear filtrate.

[0014] S3. Add the filtrate to the separatory funnel, add the organic extract, wash and extract 2-4 times, and then process to obtain the reclaimed acid solution and the metal-containing aqueous solution.

[0015] The reaction principle for the preparation of recycled acid and metal-containing aqueous solutions is as follows:

[0016] During the reaction, the filtrate is fully contacted with an organic extract composed of 1-decyl alcohol, trioctylamine, and kerosene in a separatory funnel. The acidic components and metal ions are separated by liquid-liquid extraction. Trioctylamine, a tertiary amine with a strong affinity for organic phases, can form ion-pair complexes soluble in the organic phase with the inorganic acids in the filtrate, thereby transferring the acid from the aqueous phase to the organic phase. 1-Decanol, as a co-solvent and interfacial activity modifier, can improve the compatibility and mass transfer efficiency of the extraction system. Kerosene, as a diluent, provides an inert organic phase medium, reduces the viscosity of the extraction system, and stabilizes the phase separation structure. After 2-4 extractions, the acidic components mainly enter the organic phase and can be recovered and reused through back-extraction, while the aqueous phase is enriched with metal ions, forming a metal-containing aqueous solution, thus achieving effective separation and simultaneous recovery of acid and iron ions.

[0017] S4. Adjust the alkalinity of the metal-containing aqueous solution and remove the acid to obtain recycled iron oxide;

[0018] In step S2, the cationic coagulant is prepared by: placing diallyl dimethyl ammonium chloride, OP-10 and deionized water in a nitrogen-protected reactor and stirring; adding lauryl methacrylate; heating the reactor to 45-55°C; adding azobisisobutyramidine hydrochloride; maintaining the temperature at 60-70°C for 4-6 hours; and then performing post-treatment to obtain the cationic coagulant.

[0019] The reaction principle for preparing cationic coagulants is as follows:

[0020] During the reaction, under nitrogen protection, diallyl dimethyl ammonium chloride acts as a positively charged monomer, lauryl methacrylate acts as a hydrophobic monomer containing long-chain alkyl groups, and nonionic 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 azobisisobutyramidine hydrochloride is added. It decomposes at 60-70℃ to generate free radicals, which initiate the chain copolymerization between diallyl dimethyl ammonium chloride and lauryl methacrylate, forming a cationic coagulant with both cationic charge centers and hydrophobic alkyl side chains.

[0021] 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 fume, and cationic coagulant is 15-20g:0.5-1g:0.01-0.02g; in step S3, the organic extract is composed of 1-decyl alcohol, trioctylamine, and kerosene mixed evenly in a volume ratio of 2-3:15-18:70-75; the post-treatment steps include: after washing and extraction, allowing the mixture to stand and separate into layers, separating the organic phase and the 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 a recycled acid solution.

[0022] Furthermore, the method for preparing the pretreated silica fume is as follows: silica fume is added to a tube furnace and calcined at high temperature in an air atmosphere for 1-2 hours, followed by post-treatment to obtain the pretreated silica fume.

[0023] The reaction principle for preparing pretreated silica fume is as follows:

[0024] During the reaction, silica fume is placed in a tubular furnace in an air atmosphere and calcined at high temperature. Silica fume is mainly composed of amorphous silica particles and a small amount of carbon and metal oxide impurities. In an air environment of 500-700℃, residual carbon, volatile organic compounds and adsorbed water are oxidized and removed. At the same time, some surface hydroxyl groups are dehydrated and condensed to form a more stable and larger specific surface area of ​​active silica surface. After this treatment, the silica fume particles have a clean surface, loose structure, increased reaction sites, and increased surface energy, which can enhance its adsorption and reaction ability with components such as metal ions and fluoride ions in acid mud, thereby obtaining pretreated silica fume with higher chemical activity.

[0025] Furthermore, the high-temperature calcination temperature is 500-700℃, the heating rate is 5-10℃ / min, and the post-processing steps include: 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.

[0026] Furthermore, the ratio of diallyl dimethyl ammonium chloride, OP-10, deionized water, lauryl methacrylate, and azobisisobutyramidine hydrochloride is 2-4g:0.05-0.10g:20-30mL:0.05-0.10g:0.02-0.03g. The post-treatment steps include: after the reaction is completed, wait for the reaction solution to cool to room temperature, add ethanol to the reaction solution to precipitate the precipitate, filter, wash the filter cake with ethanol 2-4 times, transfer it to an oven at 50-60℃, and dry it to constant weight to obtain a cationic coagulant.

[0027] Furthermore, in step S4, the recycled iron oxide is prepared by the following steps:

[0028] A1. Place the metal-containing aqueous solution in a reaction vessel, add sodium hydroxide solution, adjust the pH to 5-6, stir at room temperature for 15-30 min, and then process to obtain metal hydroxide.

[0029] A2. Place the metal hydroxide in a reaction vessel, add sodium hydroxide solution, adjust the pH to 10-14, stir at room temperature for 15-30 min, and then process to obtain recycled ferric hydroxide.

[0030] A3. Add the recycled ferric hydroxide into a tube furnace and calcine it at high temperature in air for 1-3 hours. The post-processing yields recycled ferric oxide.

[0031] The reaction principle for the preparation of recycled iron oxide is as follows:

[0032] In step A1, sodium hydroxide solution is added to the metal-containing aqueous solution and the pH is adjusted to 5-6. This mainly causes the iron, aluminum and other metal ions in the solution to gradually undergo hydrolysis and precipitation reactions, generating corresponding metal hydroxide precipitates, thereby achieving the initial separation and enrichment of metal components. In step A2, the pH is further increased to 10-14, which can further promote the complete precipitation of ferric ions to form ferric hydroxide, effectively removing impurity ions and improving the purity of the precipitate. Finally, in step A3, the obtained ferric hydroxide is calcined at high temperature in air for 1-3 hours to undergo a dehydration and oxidation reaction, generating a stable hematite-type ferric oxide solid product, thus obtaining recycled ferric oxide.

[0033] 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.

[0034] The present invention has the following beneficial effects:

[0035] 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.

[0036] 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.

[0037] 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

[0038] 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.

[0039] 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.

[0040] The kerosene used in the present invention is purchased from Kunshan Anwen Chemical Co., Ltd., with the model: HT and the brand:

[0041] paratherm Bosch;

[0042] The silica fume used in the present invention is purchased from Angang Industrial Micronized Aluminum Powder Co., Ltd., with the particle size: 0.05 - 0.3 μm;

[0043] The OP - 10 used in the present invention is purchased from Yixing Jianteng Chemical Co., Ltd., with the product name: octylphenol polyoxyethylene ether and the density: 0.984 g / cm 3 ;

[0044] Example 1:

[0045] This example provides a preparation method for a material treatment method for the synchronous recovery and utilization of acid and iron ions in acid sludge, including the following steps:

[0046] Step S1, prepare a cationic coagulant;

[0047] Weigh: 20 g of diallyldimethylammonium chloride, 0.5 g of OP - 10, and 200 mL of deionized water, place them in a reaction kettle under nitrogen atmosphere protection and stir. Add 0.5 g of lauryl methacrylate, heat the reaction kettle to 45 °C, add 0.2 g of azobisisobutyramidine hydrochloride, keep the temperature at 60 °C for heat preservation reaction 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 to constant weight to obtain the cationic coagulant.

[0048] Step S2, prepare pretreated silica fume;

[0049] Add silica fume into a tubular furnace, under air atmosphere, heat it to 500 °C at a heating rate of 5 °C / min, perform high - temperature calcination 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.

[0050] Step S3, prepare recycled acid solution and metal - containing aqueous solution;

[0051] [[ID=3七杀]]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 an acid sludge diluted slurry;

[0052] Weigh: 150 g of the acid sludge diluted 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 a filtrate and a fluorosilicate filter residue.

[0053] Step S4, prepare recycled iron oxide;

[0054] 1-Decanol, trioctylamine and kerosene were mixed evenly at a volume ratio of 2:15:70 to obtain an organic extract, which was then set aside.

[0055] 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.

[0056] 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;

[0057] 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.

[0058] 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.

[0059] Example 2:

[0060] 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:

[0061] Step S1: Prepare a cationic coagulant;

[0062] 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.

[0063] Step S2: Prepare pretreated silica fume;

[0064] Silica fume was added to a tube furnace and heated to 600°C at a rate of 7°C / min in an 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.

[0065] Step S3: Prepare the reclaimed acid solution and the metal-containing aqueous solution;

[0066] 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.

[0067] 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.

[0068] Step S4: Prepare recycled iron oxide;

[0069] 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.

[0070] Place the filtrate in a separatory funnel, add an organic extractant at a volume equal to that of the filtrate, shake and mix thoroughly at room temperature, wash and extract 3 times, allow to stand and separate into layers, separate to obtain an organic phase and a metal-containing aqueous solution, wash the organic phase 3 times with saturated brine, back-extract with deionized water, heat and concentrate the acid-containing aqueous phase to obtain a recycled acid solution.

[0071] 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 it to constant weight to obtain metal hydroxide;

[0072] 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;

[0073] 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.

[0074] Example 3:

[0075] 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:

[0076] Step S1: Prepare a cationic coagulant;

[0077] 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.

[0078] Step S2: Prepare pretreated silica fume;

[0079] 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.

[0080] Step S3: Prepare the reclaimed acid solution and the metal-containing aqueous solution;

[0081] 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.

[0082] 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.

[0083] Step S4: Prepare recycled iron oxide;

[0084] 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.

[0085] 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.

[0086] 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;

[0087] 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;

[0088] 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.

[0089] Comparative Example 1:

[0090] 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.

[0091] Comparative Example 2:

[0092] 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.

[0093] Comparative Example 3:

[0094] 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.

[0095] Performance testing:

[0096] 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.

[0097] 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.

[0098] 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;

[0099] The specific test results are shown in Table 1 below.

[0100] Table 1 - Performance test data of the samples:

[0101]

[0102] Data Analysis:

[0103] 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;

[0104] 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.

[0105] 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 treatment method for the simultaneous recovery and utilization of acid and iron ions from acidic sludge, characterized in that, Includes the following steps: S1. Place deionized water in a reactor, add acid mud, and stir at room temperature for 15-30 minutes to obtain diluted acid mud slurry. S2. Place the diluted acid mud slurry in a reactor, add pretreated silica fume, stir at room temperature for 15-30 minutes, add cationic coagulant, filter, and obtain filtrate and fluorinated silica filter residue. S3. Add the filtrate to the separatory funnel, add the organic extract, wash and extract 2-4 times, and then process to obtain the reclaimed acid solution and the metal-containing aqueous solution. S4. Adjust the alkalinity of the metal-containing aqueous solution and remove the acid to obtain recycled iron oxide; In step S2, the cationic coagulant is prepared by: placing diallyl dimethyl ammonium chloride, OP-10 and deionized water in a nitrogen-protected reactor and stirring; adding lauryl methacrylate; heating the reactor to 45-55°C; adding azobisisobutyramidine hydrochloride; maintaining the temperature at 60-70°C for 4-6 hours; and then performing post-treatment to obtain the cationic coagulant.

2. The material treatment method for simultaneous recovery and utilization of acid and iron ions from acidic sludge according to claim 1, characterized in that, 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 fume, and cationic coagulant is 15-20g:0.5-1g:0.01-0.02g; in step S3, the organic extract is composed of 1-decyl alcohol, trioctylamine, and kerosene mixed evenly in a volume ratio of 2-3:15-18:70-75.

3. The material treatment method for simultaneous recovery and utilization of acid and iron ions from acidic sludge according to claim 1, characterized in that, The method for preparing the pretreated silica fume is as follows: silica fume is added to a tube furnace and calcined at high temperature in an air atmosphere for 1-2 hours, followed by post-treatment to obtain the pretreated silica fume.

4. The material treatment method for simultaneous recovery and utilization of acid and iron ions from acidic sludge according to claim 3, characterized in that, The high-temperature calcination temperature is 500-700℃, and the heating rate is 5-10℃ / min.

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

6. The material treatment method for simultaneous recovery and utilization of acid and iron ions from acidic sludge according to claim 1, characterized in that, In step S4, the recycled iron oxide is prepared by the following steps: A1. Place the metal-containing aqueous solution in a reaction vessel, add sodium hydroxide solution, adjust the pH to 5-6, stir at room temperature for 15-30 min, and then process to obtain metal hydroxide. A2. Place the metal hydroxide in a reaction vessel, add sodium hydroxide solution, adjust the pH to 10-14, stir at room temperature for 15-30 min, and then process to obtain recycled ferric hydroxide. A3. Add the recycled ferric hydroxide into a tube furnace and calcine it at high temperature in air for 1-3 hours. The post-processing yields recycled ferric oxide.

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

Images