A method for recovering micronic iron oxide particles and tramp ions from sinter machine head dust using a wet dual sorting device

Abstract

The application relates to a method for recovering micron iron oxide particles and impurity ions from sintering machine head dust by using a wet double sorting device, and relates to a method for recovering micron iron oxide particles and impurity ions from a sintering machine head. The application solves the problem that soluble salts in the existing sintering machine head dust cannot be effectively classified and purified to realize effective resource utilization. The application realizes accurate partitioning of the insoluble particles by gravity and magnetic force double sorting, and guarantees the performance stability of the recovered iron oxide. The intelligent impurity removal system is used to efficiently remove impurities, and the high purity of the iron oxide is guaranteed. The application realizes the step-by-step aggregation and recovery of impurity ions, and realizes the maximum utilization of resources. The application has strong process adaptability, high operability, and is convenient for industrialization promotion. The application realizes the dual benefits of environmental protection and economy, and promotes the green development of solid waste resource utilization.

Description

Technical Field

[0001] This invention relates to a method for recovering micron-sized iron oxide particles and impurity ions from sintering machine head ash. Background Technology

[0002] Sintering machine head ash, also known as sintering electrostatic precipitator ash (or simply "machine head ash"), is a type of dust-like solid waste discharged from the sintering machine head during the sintering production process in steel enterprises. This dust is typically collected by a multi-stage electrostatic precipitator. In existing treatment methods, directly returning the machine head ash to the sintering system for recycling would lead to the enrichment of alkali metal elements within the sintering process, disrupting the stable operation of the sintering process. Specifically, this manifests as caking of the sintering machine grate bars, resulting in quality problems such as decreased sinter strength and uneven composition. Simultaneously, it accelerates the erosion of the blast furnace lining, shortening the blast furnace's service life.

[0003] Current technologies for treating solid waste such as sintering machine head ash have significant limitations: on the one hand, if direct landfill disposal is adopted, the heavy metal elements contained in the machine head ash can easily seep into the soil and groundwater, causing land and water pollution, which violates the policy requirements of green development and environmental protection; on the other hand, if the disposal is outsourced to a third party, a disposal fee of tens to hundreds of yuan per ton of machine head ash must be paid, which is not conducive to improving the economic benefits of enterprises.

[0004] However, sintering machine head ash contains high resource value. Its ash content not only contains a large amount of iron (Fe), but also some valuable metal elements such as K, Na, Cu, Ca, and Pb. These elements mainly exist as insoluble micron-sized iron oxides (Fe₂O₃) and soluble chlorides (KCl, NaCl). Among these, the high-value-added micron-sized iron oxides have a wide range of applications: they can be used as mineral pigments, as building material additives, and as catalysts in anaerobic alkylation processes to increase the alkylation rate; they can catalyze the decomposition of carbon monoxide, used to rapidly reduce the concentration of toxic gases in confined spaces such as mines and factories; they can also be used in magnetic seals and magnetic recording media devices, exhibiting zero leakage and high-temperature resistance; they can also be used as pigments and coatings for anti-counterfeiting coatings, inks, and high-temperature coatings; and they have certain application value in the biomedical field, such as targeted drug delivery.

[0005] In existing technologies, soluble salts in sintering mill head ash can be separated and recovered through water washing and salt extraction processes. However, the classification, purification, and separation of insoluble substances (mainly micron-sized iron oxides and heterometallic compounds) for subsequent resource utilization remains a challenge, lacking relevant research and facing key technological bottlenecks. After soluble salt extraction from sintering mill head ash, the insoluble particles are coated with a large amount of heavy metal impurities, and the particle groups exhibit uneven composition, large particle size differences, and significant fluctuations in elemental content. Existing treatment methods cannot effectively classify and purify them. The mixed insoluble substances not only limit the realization of high-value-added applications of micron-sized iron oxides but also result in the waste of valuable metal elements such as Cu and Pb. Therefore, developing a technical solution capable of accurately classifying and efficiently removing impurities from sintering mill head ash, and achieving resource recovery of these impurities, has become a critical issue urgently needing to be addressed in the field of solid waste resource utilization in steel enterprises. Summary of the Invention

[0006] This invention addresses the problem of ineffective classification and purification of insoluble substances after extracting soluble salts from sintering die head ash. It proposes a method using a wet dual-sorting device to classify, purify, and recover iron oxide micron-sized particles and heterometallic compounds from the insoluble substances in sintering die head ash. This method efficiently removes heavy metal impurities from the iron oxide micron-sized particles with minimal loss, yielding high-purity iron oxide micron-sized particles free of heavy metal contamination. Furthermore, it recovers various valuable metal ions from the heavy metal removal solution in stages, maximizing resource utilization. This reduces processing costs, avoids environmental pollution, and promotes the green development of sintering die head ash resource utilization.

[0007] The present invention utilizes a wet dual-separation device to recover micron-sized iron oxide particles and impurity ions from sintering die head ash, and the method comprises the following steps:

[0008] Step 1: Gravity and Magnetic Dual Separation

[0009] Extract the insoluble ash from the sintering machine head ash, transfer the insoluble ash to the stirring tank (1), fill the sorting chamber of the gravity and magnetic dual sorting device with water, and return the effluent from the three-stage sedimentation chamber (5) to the stirring tank (1) through the pipe (8), and turn on the agitator (6) to make the material in the stirring tank (1) fluidized; the material in the sorting chamber passes through each sedimentation chamber in sequence and achieves the sorting of insoluble ash, and finally collects the insoluble ash in each sedimentation chamber and dries it; the insoluble ash includes strongly magnetic small particles, strongly magnetic large particles, medium magnetic small particles, and weakly magnetic small particles;

[0010] The magnetic retention chamber (2) is used to collect strongly magnetic small particles. The magnetic adsorption force of the target particles in the magnetic retention chamber (2) is stronger than the impact force of the water flow and gravity, so that the strongly magnetic small particles in the insoluble ash are retained in the magnetic retention chamber (2); the baffle plate (12) between the magnetic retention chamber (2) and the primary sedimentation chamber (3) can be used to adjust the water flow rate, which is set to 0.5~5 cm / s;

[0011] The primary sedimentation chamber (3) is still within the magnetic influence range and is used to collect large magnetic particles. Their gravity and particle size are slightly larger, and they are easily carried away by the water flow and leave the magnetic interception chamber (2) to enter the primary sedimentation chamber (3). The water flow rate in the primary sedimentation chamber (3) slows down, and the insoluble ash in the primary sedimentation chamber (3) takes 3~30s to pass through, which causes the large magnetic particles to settle. The first overflow plate (9) is used to adjust the interception capacity of the primary sedimentation chamber (3).

[0012] The secondary sedimentation chamber (4) is used to collect small magnetic particles; the material carrying insoluble ash flowing out of the primary sedimentation chamber (3) enters the secondary sedimentation chamber (4). The magnetic force of the secondary sedimentation chamber (4) on the target particles is lower than that of gravity and water flow. The second overflow plate (10) in the secondary sedimentation chamber (4) is used to adjust the retention capacity of the secondary sedimentation chamber (4). The insoluble ash flows through the secondary sedimentation chamber (4) for 3~30s.

[0013] The third-stage sedimentation chamber (5) is used to collect weakly magnetic small particles; the material carrying insoluble ash flowing out of the second-stage sedimentation chamber (4) enters the third-stage sedimentation chamber (5), and the insoluble ash flows through the third-stage sedimentation chamber (5) for 10~100s;

[0014] The third overflow plate (11) in the three-stage sedimentation chamber (5) is used to adjust the liquid level in the magnetic interception chamber (2), the first-stage sedimentation chamber (3) and the second-stage sedimentation chamber (4). The effluent from the three-stage sedimentation chamber (5) is clear and the particulate matter content is below 100 mg / L. The effluent is returned to the stirring tank (1) through the pipe (8).

[0015] The gravity-magnetic dual separation device consists of a mixing tank (1) and a separation chamber; the separation chamber includes a magnetic interception chamber (2), a primary sedimentation chamber (3), a secondary sedimentation chamber (4), and a tertiary sedimentation chamber (5) arranged sequentially; the mixing tank (1) is located on the feed side of the magnetic interception chamber (2), and a stirrer (6) is installed inside the mixing tank (1); a magnet (7) is installed on the side of the magnetic interception chamber (2) below the mixing tank (1); the outlet of the tertiary sedimentation chamber (5) is connected to the inlet of the mixing tank (1) through a pipe (8); a top material passage is provided on the upper part of the partition between the magnetic interception chamber (2) and the mixing tank (1), and between the magnetic interception chamber (2) and the primary sedimentation chamber (3), and between the primary sedimentation chamber (3) and the... A baffle plate (12) is provided between the secondary sedimentation chambers (4) and between the secondary sedimentation chamber (4) and the tertiary sedimentation chamber (5). The upper end of the baffle plate (12) is connected to the top of the sorting chamber, and the lower end of the baffle plate is provided with a bottom material passage. A first overflow plate (9) is provided on the water inlet side of the baffle plate between the primary sedimentation chamber (3) and the secondary sedimentation chamber (4). A second overflow plate (10) is provided on the water inlet side of the baffle plate between the secondary sedimentation chamber (4) and the tertiary sedimentation chamber (5). A third overflow plate (11) is provided on the water outlet side of the tertiary sedimentation chamber (5). The bottoms of the first overflow plate (9), the second overflow plate (10) and the third overflow plate (11) are fixed to the bottom plate of the sorting chamber, and the upper ends of the first overflow plate (9), the second overflow plate (10) and the third overflow plate (11) are all higher than the lower end of the baffle plate.

[0016] Step 2: Separation and removal of iron oxide particles

[0017] ① The insoluble ash is digested to obtain a solution of insoluble ash, and the types and contents of impurities in the solution are determined to clarify the composition of the entire insoluble ash.

[0018] ② The insoluble ash obtained from the magnetic retention chamber (2) and precipitation chamber is eluted with an eluent, and solid-liquid separation is performed to obtain a cleaned liquid and iron oxide particles; the types and contents of impurities in the cleaned liquid are determined and compared with the types and contents of impurities measured in the digestion solution in step 2 ①. If the content of impurities in the cleaned liquid is lower than the measured value in step 2 ①, the elution time is increased and the concentration of the eluent is increased until the content of impurities in the cleaned liquid is not lower than the measured value in step 2 ①; the eluent can remove the Ca coating on the surface of the insoluble ash. 2+ Mg 2+ Cu 2+ Pb 2+ Al 3+ Dissolving compounds containing impurities such as Ca2+ in the resulting purified solution yields a solution containing Ca2+. 2+ Mg 2+ Cu 2+ Pb 2+ Al 3+ Para-ions;

[0019] Step 3: Collect impurity ions in the impurity removal solution by precipitation.

[0020] ① The order of precipitation reaction between the precipitant and impurity ions in the purification solution and the theoretical amount of precipitant added were simulated using HYDRA / MEDUSA software;

[0021] ② Following the reaction sequence obtained from the simulation, the precipitant and impurity removal solution were reacted until the impurity ions were completely precipitated, and the amount of precipitant added and the reaction time were verified.

[0022] ③ Following the reaction sequence in step 3① and the amount of precipitant added and reaction time obtained in step ②, precipitate the impurity ions in the impurity removal solution and collect them.

[0023] The principle and beneficial effects of this invention are as follows:

[0024] (1) The present invention realizes the precise partitioning of sparingly soluble particles by gravity and magnetic dual separation, which ensures the performance stability of the recovered iron oxide.

[0025] Due to the significant differences in particle size, magnetic strength, and iron content of insoluble particles in sintering die head ash, the performance of iron oxides is unstable, leading to fluctuations in catalytic efficiency and poor magnetic uniformity. Existing treatment methods do not effectively classify the insoluble components of the die head ash, and most methods still treat it as a mixed particle, failing to meet the core requirement of material uniformity for high-value-added applications such as catalysis and magnetic material preparation. To address the limitation of existing technologies in not classifying the insoluble components of die head ash, this invention combines the magnetic properties of iron oxides with the gravitational differences in particle size or density. Through a dual gravity and magnetic sorting method, the insoluble components are divided into four regions. The particles in each region exhibit stable and uniform characteristics in terms of iron content, magnetic strength, and particle size. This solves the problems of fluctuating functional efficiency and unstable magnetic properties in traditional mixed particle applications, meeting the performance stability requirements of iron oxides in various applications such as catalysis, magnetic materials, and high-temperature coatings.

[0026] (2) The present invention utilizes an intelligent impurity removal system to efficiently remove impurities and ensure the high purity of iron oxides.

[0027] Because the insoluble impurities in the sintering die head ash include Cu... 2+ Pb 2+With high iron oxide content, without effective impurity removal, the insoluble iron oxide particles in the sintering machine head ash are difficult to apply for high-value applications. Most can only be used in building material preparation, and there is a risk of heavy metal leaching after a long period. Furthermore, the reaction sequence during the removal of heavy metal impurities is unclear, and the dosage of the impurity-removing agent is difficult to control, leading to iron oxide loss and incomplete impurity removal. Moreover, existing impurity removal methods rely on empirical dosage, which cannot guarantee a balance between iron oxide purity, impurity ion removal, and impurity ion classification and separation. This invention constructs a three-stage impurity removal parameter determination system consisting of "elution and impurity removal - software simulation - experimental verification." First, digestion with hydrochloric acid and nitric acid completely dissolves the insoluble solid coating of heavy metal impurities in each zone, solving the problem of high-value utilization of iron oxides mixed with large amounts of heavy metals. Inductively coupled plasma atomic emission spectrometry (ICP-AES) is then used to accurately determine the ion content in the sample. Next, HYDRA / MEDUSA software simulates the sequence of impurity removal reactions and determines the theoretical dosage of the impurity removal agent, ensuring no reaction with iron oxides and controlling the amount added. Impurity ions are thoroughly removed without iron oxide participation in the reaction. Finally, experiments are conducted to verify the system and determine the optimal amount of precipitant and reaction time, saving unnecessary experiments and achieving Ca… 2+ Mg 2+ Cu 2+ Pb 2+ Al 3+ The removal rate of impurities is ≥90%, and the iron content in the treated product is ≥65%, meeting the purity requirements of iron oxides for high value-added applications.

[0028] (3) This invention realizes the graded aggregation and recovery of heterogeneous ions, thereby maximizing the utilization of resources.

[0029] This invention uses Medusa software to simulate the reagents and dosages required for the precipitation of various ions, and verifies this through experiments. Sodium hydroxide and sodium sulfide are used as precipitants; sodium sulfide first precipitates Cu... 2+ Pb 2+ The components are successively converted to CuS and PbS, then NaOH is added to adjust the pH, and Al is added sequentially. 3+ Mg 2+ Ca 2+ It is converted into Al(OH)3, Mg(OH)2, and Ca(OH)2, with a recovery rate of ≥ 95% for each impurity ion and a product purity of ≥ 90%. This avoids the resource waste caused by traditional mixing treatment, realizes the transformation of impurities into resources, and further enhances the resource value of sintering machine head ash.

[0030] (4) The process of this invention is highly adaptable and operable, making it easy to promote industrialization.

[0031] The equipment used in this invention, such as electric heating plates and inductively coupled plasma emission spectrometers, is readily available. The gravity and magnetic dual-separation device is easy to manufacture and occupies a small area. Process parameters, such as settling time and pH adjustment, are easily controlled. It can be adapted to similar solid wastes such as dry blast furnace ash and iron-containing dust and sludge from steel enterprises. It is not only suitable for the treatment of sintering machine head ash, but can also be extended to other iron-containing solid waste resource utilization fields such as waste incineration fly ash and blast furnace ash. At the same time, the impurity removal and impurity ion removal sections have a wide range of applications and can be used for solid particles containing other impurities. It is highly operable and adaptable, and easy to promote and apply on an industrial scale.

[0032] (5) This invention achieves both environmental and economic benefits, and promotes the green development of solid waste resource utilization.

[0033] This invention changes the traditional disposal model of directly landfilling sintering machine head ash, which pollutes the soil and incurs high outsourcing costs. It transforms solid waste into high-value resources. Each ton of machine head ash can not only reduce outsourcing costs but also generate additional economic benefits. At the same time, it avoids land pollution caused by landfilling, turning waste into treasure, and taking into account both environmental and economic benefits, which meets the requirements of green circular economy development. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of the wet dual-sorting device of the present invention;

[0035] Figure 2 This is a photograph of the insoluble ash obtained by gravity and magnetic dual separation in Example 1.

[0036] Figure 3 The particle size distribution diagram of insoluble ash obtained by gravity and magnetic dual separation in Example 1 is shown.

[0037] Figure 4 XRD patterns of strongly magnetic large particles (QD), strongly magnetic small particles (QX), and medium magnetic small particles (ZX) after impurity removal;

[0038] Figure 5 The graph shows the removal rate curves of impurity ions in different parts of strongly magnetic small particles, strongly magnetic large particles, medium magnetic small particles, and weakly magnetic small particles.

[0039] Figure 6 Comparison of ion recovery rates after collection of impurity ions by precipitation;

[0040] Figure 7 This is a particle size distribution diagram of strongly magnetic small particles, strongly magnetic large particles, medium magnetic small particles, and weakly magnetic small particles after impurity removal by dilute hydrochloric acid. Detailed Implementation

[0041] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any reasonable combination of the specific embodiments.

[0042] Specific Implementation Method 1: This implementation method for recovering micron-sized iron oxide particles and impurity ions from sintering die head ash using a wet dual-separation device is carried out according to the following steps:

[0043] Step 1: Gravity and Magnetic Dual Separation

[0044] Extract the insoluble ash from the sintering machine head ash, transfer the insoluble ash to the stirring tank (1), fill the sorting chamber of the gravity and magnetic dual sorting device with water, and return the effluent from the three-stage sedimentation chamber (5) to the stirring tank (1) through the pipe (8), and turn on the agitator (6) to make the material in the stirring tank (1) fluidized; the material in the sorting chamber passes through each sedimentation chamber in sequence and achieves the sorting of insoluble ash, and finally collects the insoluble ash in each sedimentation chamber and dries it; the insoluble ash includes strongly magnetic small particles, strongly magnetic large particles, medium magnetic small particles, and weakly magnetic small particles;

[0045] The magnetic retention chamber (2) is used to collect strongly magnetic small particles. The magnetic adsorption force of the target particles in the magnetic retention chamber (2) is stronger than the impact force of the water flow and gravity, so that the strongly magnetic small particles in the insoluble ash are retained in the magnetic retention chamber (2); the baffle plate (12) between the magnetic retention chamber (2) and the primary sedimentation chamber (3) can be used to adjust the water flow rate, which is set to 0.5~5 cm / s;

[0046] The primary sedimentation chamber (3) is still within the magnetic influence range and is used to collect large magnetic particles. Their gravity and particle size are slightly larger, and they are easily carried away by the water flow and leave the magnetic interception chamber (2) to enter the primary sedimentation chamber (3). The water flow rate in the primary sedimentation chamber (3) slows down, and the insoluble ash in the primary sedimentation chamber (3) takes 3~30s to pass through, which causes the large magnetic particles to settle. The first overflow plate (9) is used to adjust the interception capacity of the primary sedimentation chamber (3).

[0047] The secondary sedimentation chamber (4) is used to collect small magnetic particles; the material carrying insoluble ash flowing out of the primary sedimentation chamber (3) enters the secondary sedimentation chamber (4). The magnetic force of the secondary sedimentation chamber (4) on the target particles is lower than that of gravity and water flow. The second overflow plate (10) in the secondary sedimentation chamber (4) is used to adjust the retention capacity of the secondary sedimentation chamber (4). The insoluble ash flows through the secondary sedimentation chamber (4) for 3~30s.

[0048] The third-stage sedimentation chamber (5) is used to collect weakly magnetic small particles; the material carrying insoluble ash flowing out of the second-stage sedimentation chamber (4) enters the third-stage sedimentation chamber (5), and the insoluble ash flows through the third-stage sedimentation chamber (5) for 10~100s;

[0049] The third overflow plate (11) in the three-stage sedimentation chamber (5) is used to adjust the liquid level in the magnetic interception chamber (2), the first-stage sedimentation chamber (3) and the second-stage sedimentation chamber (4). The effluent from the three-stage sedimentation chamber (5) is clear and the particulate matter content is below 100 mg / L. The effluent is returned to the stirring tank (1) through the pipe (8).

[0050] The gravity-magnetic dual separation device consists of a mixing tank (1) and a separation chamber; the separation chamber includes a magnetic interception chamber (2), a primary sedimentation chamber (3), a secondary sedimentation chamber (4), and a tertiary sedimentation chamber (5) arranged sequentially; the mixing tank (1) is located on the feed side of the magnetic interception chamber (2), and a stirrer (6) is installed inside the mixing tank (1); a magnet (7) is installed on the side of the magnetic interception chamber (2) below the mixing tank (1); the outlet of the tertiary sedimentation chamber (5) is connected to the inlet of the mixing tank (1) through a pipe (8); a top material passage is provided on the upper part of the partition between the magnetic interception chamber (2) and the mixing tank (1), and between the magnetic interception chamber (2) and the primary sedimentation chamber (3), and between the primary sedimentation chamber (3) and the... A baffle plate (12) is provided between the secondary sedimentation chambers (4) and between the secondary sedimentation chamber (4) and the tertiary sedimentation chamber (5). The upper end of the baffle plate (12) is connected to the top of the sorting chamber, and the lower end of the baffle plate is provided with a bottom material passage. A first overflow plate (9) is provided on the water inlet side of the baffle plate between the primary sedimentation chamber (3) and the secondary sedimentation chamber (4). A second overflow plate (10) is provided on the water inlet side of the baffle plate between the secondary sedimentation chamber (4) and the tertiary sedimentation chamber (5). A third overflow plate (11) is provided on the water outlet side of the tertiary sedimentation chamber (5). The bottoms of the first overflow plate (9), the second overflow plate (10) and the third overflow plate (11) are fixed to the bottom plate of the sorting chamber, and the upper ends of the first overflow plate (9), the second overflow plate (10) and the third overflow plate (11) are all higher than the lower end of the baffle plate.

[0051] Step 2: Separation and removal of iron oxide particles

[0052] ① The insoluble ash is digested to obtain a solution of insoluble ash, and the types and contents of impurities in the solution are determined to clarify the composition of the entire insoluble ash.

[0053] ② The insoluble ash obtained from the magnetic retention chamber (2) and precipitation chamber is eluted with an eluent, and solid-liquid separation is performed to obtain a cleaned liquid and iron oxide particles; the types and contents of impurities in the cleaned liquid are determined and compared with the types and contents of impurities measured in the digestion solution in step 2 ①. If the content of impurities in the cleaned liquid is lower than the measured value in step 2 ①, the elution time is increased and the concentration of the eluent is increased until the content of impurities in the cleaned liquid is not lower than the measured value in step 2 ①; the eluent can remove the Ca coating on the surface of the insoluble ash. 2+ Mg 2+ Cu 2+ Pb 2+ Al3+ Dissolving compounds containing impurities such as Ca2+ in the resulting purified solution yields a solution containing Ca2+. 2+ Mg 2+ Cu 2+ Pb 2+ Al 3+ Para-ions;

[0054] Step 3: Collect impurity ions in the impurity removal solution by precipitation.

[0055] ① The order of precipitation reaction between the precipitant and impurity ions in the purification solution and the theoretical amount of precipitant added were simulated using HYDRA / MEDUSA software;

[0056] ② Following the reaction sequence obtained from the simulation, the precipitant and impurity removal solution were reacted until the impurity ions were completely precipitated, and the amount of precipitant added and the reaction time were verified.

[0057] ③ Following the reaction sequence in step 3① and the amount of precipitant added and reaction time obtained in step ②, precipitate the impurity ions in the impurity removal solution and collect them.

[0058] The principle and beneficial effects of this implementation method are as follows:

[0059] (1) This embodiment realizes gravity and magnetic dual separation to achieve precise partitioning of insoluble particles, ensuring the performance stability of the recovered iron oxide.

[0060] Due to the significant differences in particle size, magnetic strength, and iron content of insoluble particles in sintering die head ash, the performance of iron oxides is unstable, leading to issues such as fluctuating catalytic efficiency and poor magnetic uniformity. Existing treatment methods do not effectively classify the insoluble components of the die head ash, and most methods still treat it as a mixed particle, failing to meet the core requirement of material uniformity for high-value-added applications such as catalysis and magnetic material preparation. This embodiment addresses the limitation of existing technologies in classifying the insoluble components of die head ash by combining the magnetic properties of iron oxides with the gravitational differences in particle size or density. It uses a dual gravity and magnetic sorting method to divide the insoluble components into four regions. The particles in each region exhibit stable and uniform characteristics in terms of iron content, magnetic strength, and particle size, solving the problems of fluctuating functional efficiency and unstable magnetic properties in traditional mixed particle applications. This meets the performance stability requirements of iron oxides in different applications such as catalysis, magnetic materials, and high-temperature coatings.

[0061] (2) This embodiment utilizes an intelligent impurity removal system to efficiently remove impurities and ensure the high purity of iron oxides.

[0062] Because the insoluble impurities in the sintering die head ash include Cu... 2+ Pb 2+With high iron oxide content, without effective impurity removal, the insoluble iron oxide particles in the sintering machine head ash are difficult to apply for high-value applications. Most can only be used in building material preparation, and there is a risk of heavy metal leaching after a long period. Furthermore, the reaction sequence during the removal of heavy metal impurities is unclear, and the dosage of the impurity-removing agent is difficult to control, leading to iron oxide loss and incomplete impurity removal. Moreover, existing impurity removal methods rely on empirical dosage, which cannot guarantee a balance between iron oxide purity, impurity ion removal, and impurity ion classification and separation. This implementation method constructs a three-stage impurity removal parameter determination system consisting of "elution and impurity removal - software simulation - experimental verification." First, digestion with hydrochloric acid and nitric acid completely dissolves the insoluble solid coating of heavy metal impurities in each zone, solving the problem of high-value utilization of iron oxides mixed with large amounts of heavy metals. Inductively coupled plasma atomic emission spectrometry (ICP-AES) is then used to accurately determine the ion content in the sample. Next, HYDRA / MEDUSA software simulates the sequence of impurity removal reactions and determines the theoretical dosage of the impurity removal agent, ensuring no reaction with iron oxides and controlling the amount added. This completely removes impurity ions without iron oxide participation in the reaction. Finally, experiments are conducted to verify the system and determine the optimal amount of precipitant and reaction time, saving unnecessary experiments and achieving Ca… 2+ Mg 2+ Cu 2+ Pb 2+ Al 3+ The removal rate of impurities is ≥90%, and the iron content in the treated product is ≥65%, meeting the purity requirements of iron oxides for high value-added applications.

[0063] (3) This embodiment realizes the graded aggregation and recovery of heterogeneous ions, thereby maximizing the utilization of resources.

[0064] This implementation method uses Medusa software to simulate the reagents and dosages required for each ion precipitation, and verifies this through experiments. Sodium hydroxide and sodium sulfide are used as precipitants; sodium sulfide first precipitates Cu... 2+ Pb 2+ The components are successively converted to CuS and PbS, then NaOH is added to adjust the pH, and Al is added sequentially. 3+ Mg 2+ Ca 2+ It is converted into Al(OH)3, Mg(OH)2, and Ca(OH)2, with a recovery rate of ≥95% for each impurity ion and a product purity of ≥90%. This avoids the resource waste caused by traditional mixing treatment, realizes the transformation of impurities into resources, and further enhances the resource value of sintering machine head ash.

[0065] (4) This embodiment has strong process adaptability and high operability, and is easy to promote industrialization.

[0066] The equipment used in this embodiment, such as electric heating plates and inductively coupled plasma emission spectrometers, is readily available. The gravity and magnetic dual separation device is easy to manufacture and occupies a small area. Process parameters, such as settling time and pH adjustment, are easy to control. It can be adapted to similar solid wastes such as dry blast furnace ash and iron-containing dust and sludge from steel enterprises. It is not only suitable for the treatment of sintering machine head ash, but can also be extended to other iron-containing solid waste resource utilization fields such as waste incineration fly ash and blast furnace ash. At the same time, the impurity removal and impurity ion removal sections have a wide range of applications and can be used for solid particles containing other impurities. It is highly operable and adaptable, and easy to promote and apply on an industrial scale.

[0067] (5) This implementation method achieves both environmental and economic benefits and promotes the green development of solid waste resource utilization.

[0068] This implementation method changes the traditional disposal model of directly landfilling sintering machine head ash, which pollutes the soil and incurs high outsourcing costs. It transforms solid waste into high-value resources. Each ton of machine head ash can not only reduce outsourcing costs but also generate additional economic benefits. At the same time, it avoids land pollution caused by landfilling, turning waste into treasure, and taking into account both environmental and economic benefits, which meets the requirements of green circular economy development.

[0069] Specific implementation method two: This implementation method differs from specific implementation method one in that: in step one, the height of the first overflow plate (9) and the second overflow plate (10) is 20%-50% of the height of the third overflow plate (11); the distance between the lower end of the intercepting plate (12) and the bottom of the sorting chamber is 10%-20% of the height of the sorting chamber.

[0070] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that the extraction process of insoluble ash in step 1 is as follows: Take the ash from the sintering machine head to be treated, add water to dissolve it, then filter to remove soluble salts, and collect the filter residue as insoluble ash.

[0071] Specific implementation method four: This implementation method differs from one of the specific implementation methods one to three in that the speed of the stirrer (6) in step one is 100-500 rpm.

[0072] Specific implementation method five: This implementation method differs from one of the specific implementation methods one to four in that: the magnetic interception chamber (2) described in step one is provided with a guide plate (13), which is a step or an inclined plate.

[0073] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: the digestion process in step two① is as follows: Take the dried insoluble ash and place it in a polytetrafluoroethylene crucible. Add concentrated hydrochloric acid, concentrated nitric acid, hydrofluoric acid, and perchloric acid, and heat the crucible to 100~220℃. The ratio of concentrated hydrochloric acid, concentrated nitric acid, hydrofluoric acid, and perchloric acid to insoluble ash is 1~8mL:0.2g. The mass fraction of concentrated hydrochloric acid is 30%~35%, the mass fraction of concentrated nitric acid is 60~65%, the mass fraction of hydrofluoric acid is 35~40%, and the mass fraction of perchloric acid is 65~72%. Hydrofluoric acid decomposes the quartz component, the combination of concentrated nitric acid and concentrated hydrochloric acid allows the iron oxide to dissolve faster and more completely, and perchloric acid is suitable when the solution is not clear.

[0074] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that: the eluent in step two ② is one or a mixture of two of dilute hydrochloric acid and dilute nitric acid in any proportion, and the concentration of the eluent is 0.1-1 mol / L.

[0075] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: the process for determining the types and contents of impurity ions in the solution in step two① is as follows: the solution is diluted with water, and the types and contents of each ion in the solution are determined by inductively coupled plasma optical emission spectroscopy (ICP).

[0076] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the process for determining the content of impurity ions in the impurity removal solution in step two ② is as follows: the impurity removal solution is diluted with water, and the content of each ion in the solution is determined by inductively coupled plasma optical emission spectroscopy (ICP).

[0077] Specific Implementation Method 10: This implementation method differs from Specific Implementation Methods 1 to 9 in that the precipitant mentioned in step 3 is one or both of sodium hydroxide and sodium sulfide.

[0078] Example 1:

[0079] This embodiment describes a method for recovering micron-sized iron oxide particles and impurity ions from sintering die head ash using a wet dual-separation device, which is carried out according to the following steps:

[0080] Step 1: Gravity and Magnetic Dual Separation

[0081] The extraction process of insoluble ash from sintering machine head ash is as follows: Take 1 kg of sintering machine head ash to be treated, add 10 L of water, stir at 400 rpm for 20 min, remove soluble salts by vacuum filtration through 0.45 µm filter paper, and collect the filter residue as insoluble ash; transfer the insoluble ash to the stirring tank (1), fill the separation chamber of the gravity and magnetic dual separation device with water, return the effluent from the three-stage sedimentation chamber (5) to the stirring tank (1) through the pipe (8), and turn on the stirrer (6). The speed of the stirrer (6) is 400 rpm, so that the material in the stirring tank (1) is in a fluidized state; the material in the separation chamber passes through each sedimentation chamber in sequence and achieves the separation of insoluble ash, and finally collects the insoluble ash in each sedimentation chamber and dries it; the drying temperature is 105℃; the insoluble ash includes strongly magnetic small particles, strongly magnetic large particles, medium magnetic small particles, and weakly magnetic small particles;

[0082] The magnetic trapping chamber (2) is used to collect strongly magnetic small particles. The magnetic adsorption force of the target trapped particles in the magnetic trapping chamber (2) is stronger than the impact force of water flow and gravity, so that the strongly magnetic small particles in the insoluble ash are trapped in the magnetic trapping chamber (2); the baffle plate (12) between the magnetic trapping chamber (2) and the primary sedimentation chamber (3) can be used to adjust the water flow rate, which is set to 2 cm / s;

[0083] The primary sedimentation chamber (3) is still within the magnetic influence range and is used to collect large magnetic particles with strong gravity and particle size. They are easily carried away by the water flow and leave the magnetic interception chamber (2) to enter the primary sedimentation chamber (3). The water flow rate in the primary sedimentation chamber (3) slows down, and the insoluble ash flows through the primary sedimentation chamber (3) for 10 seconds, causing the large magnetic particles to settle. The first overflow plate (9) is used to adjust the interception capacity of the primary sedimentation chamber (3).

[0084] The secondary sedimentation chamber (4) is used to collect small magnetic particles; the material carrying insoluble ash flowing out of the primary sedimentation chamber (3) enters the secondary sedimentation chamber (4). The magnetic force of the secondary sedimentation chamber (4) on the target particles is lower than that of gravity and water flow. The second overflow plate (10) in the secondary sedimentation chamber (4) is used to adjust the retention capacity of the secondary sedimentation chamber (4). The insoluble ash flows through the secondary sedimentation chamber (4) for 10 seconds.

[0085] The third-stage sedimentation chamber (5) is used to collect weakly magnetic small particles; the material carrying insoluble ash flowing out of the second-stage sedimentation chamber (4) enters the third-stage sedimentation chamber (5), and the insoluble ash flows through the third-stage sedimentation chamber (5) for 20 seconds;

[0086] The third overflow plate (11) in the three-stage sedimentation chamber (5) is used to adjust the liquid level in the magnetic interception chamber (2), the first-stage sedimentation chamber (3) and the second-stage sedimentation chamber (4). The effluent from the three-stage sedimentation chamber (5) is clear and the particulate matter content is below 100 mg / L. The effluent is returned to the stirring tank (1) through the pipe (8).

[0087] The mass percentage of iron oxides in each part after sorting: about 8% of the unfluidized part in the gravity and magnetic double sorting, 11% of the part that can be magnetically retained, about 62% of the part precipitated in the first-stage sedimentation chamber (3), about 18% of the part precipitated in the second-stage sedimentation chamber (4), and <1% of the precipitate that can be collected in the third-stage sedimentation chamber (5).

[0088] The gravity and magnetic dual separation device consists of a stirring tank (1) and a separation chamber. The separation chamber includes a magnetic interception chamber (2), a primary sedimentation chamber (3), a secondary sedimentation chamber (4), and a tertiary sedimentation chamber (5) arranged sequentially. The stirring tank (1) is located on the feed side of the magnetic interception chamber (2), and a stirrer (6) is installed inside the stirring tank (1). A magnet (7) is installed on the side of the magnetic interception chamber (2) below the stirring tank (1). The outlet of the tertiary sedimentation chamber (5) is connected to the inlet of the stirring tank (1) through a pipe (8). A top material passage is provided on the upper part of the partition between the magnetic interception chamber (2) and the stirring tank (1). A flow interceptor (12) is installed between the magnetic interception chamber (2) and the primary sedimentation chamber (3), between the primary sedimentation chamber (3) and the secondary sedimentation chamber (4), and between the secondary sedimentation chamber (4) and the tertiary sedimentation chamber (5). The upper end is connected to the top of the sorting chamber, and the lower end of the interceptor plate is provided with a bottom material passage; the water inlet side of the interceptor plate between the primary sedimentation chamber (3) and the secondary sedimentation chamber (4) is provided with a first overflow plate (9), the water inlet side of the interceptor plate between the secondary sedimentation chamber (4) and the tertiary sedimentation chamber (5) is provided with a second overflow plate (10), and the water outlet side of the tertiary sedimentation chamber (5) is provided with a third overflow plate (11); the bottom of the first overflow plate (9), the second overflow plate (10) and the third overflow plate (11) are fixed to the bottom plate of the sorting chamber, and the upper end of each is higher than the lower end of the interceptor plate; the height of the first overflow plate (9) and the second overflow plate (10) is 25% of the height of the third overflow plate (11), and the height of the second overflow plate (10) is 50% of the height of the third overflow plate (11); the distance between the lower end of the interceptor plate (12) and the bottom of the sorting chamber is 20% of the height of the sorting chamber. The magnetic interception chamber (2) is equipped with a flow guide plate (13), which is a stepped or inclined plate.

[0089] Step 2: Separation and removal of iron oxide particles

[0090] ① The insoluble ash is digested to obtain a solution of insoluble ash, and the types and contents of impurities in the solution are determined to clarify the composition of the entire insoluble ash.

[0091] The digestion process is as follows: Take 0.2g of dried insoluble ash and place it in a polytetrafluoroethylene crucible. Add 5mL of concentrated hydrochloric acid, 5mL of concentrated nitric acid, 5mL of hydrofluoric acid and 5mL of perchloric acid in sequence, and heat the crucible to 200℃. The mass fraction of the concentrated hydrochloric acid is 35%, the mass fraction of the concentrated nitric acid is 65%, the mass fraction of the hydrofluoric acid is 40%, and the mass fraction of the perchloric acid is 72%.

[0092] The process for determining the types and contents of impurity ions in the solution is as follows: dilute the solution 10 times with water, and determine the contents of impurity ions in the solution by inductively coupled plasma optical emission spectrometry (ICP).

[0093] ② The insoluble ash obtained from the magnetic retention chamber (2) and precipitation chamber is eluted with an eluent, and solid-liquid separation is performed to obtain a cleaned liquid and iron oxide particles; the types and contents of impurities in the cleaned liquid are determined and compared with the types and contents of impurities measured in the digestion solution in step 2 ①. If the content of impurities in the cleaned liquid is lower than the measured value in step 2 ①, the elution time is increased and the concentration of the eluent is increased until the content of impurities in the cleaned liquid is not lower than the measured value in step 2 ①; the eluent can remove the Ca coating on the surface of the insoluble ash. 2+ Mg 2+ Cu 2+ Pb 2+ Al 3+ Dissolving compounds containing impurities such as Ca2+ in the resulting purified solution yields a solution containing Ca2+. 2+ Mg 2+ Cu 2+ Pb 2+ Al 3+ Para-ions;

[0094] The eluent is dilute hydrochloric acid with a concentration of 0.5 mol / L; the elution time is 30 min.

[0095] The process for determining the content of impurity ions in the impurity removal solution in step 2② is as follows: dilute the impurity removal solution 10 times with water, and determine the content of each ion in the solution by inductively coupled plasma optical emission spectrometry (ICP).

[0096] Step 3: Collect impurity ions in the impurity removal solution by precipitation.

[0097] ① The order of precipitation reactions between the precipitant and impurity ions in the purification solution and the theoretical amount of precipitant added were simulated using HYDRA / MEDUSA software. The simulation results showed that the reaction order was Cu... 2+ Pb 2+ Al 3+ Mg 2+ Ca 2+The precipitant is sodium hydroxide and sodium sulfide.

[0098] ② Following the reaction sequence obtained from the simulation, the precipitant and impurity removal solution were reacted until the impurity ions were completely precipitated, and the amount of precipitant added and the reaction time were verified.

[0099] The order of reaction, the amount of precipitant added, and the reaction time are as follows:

[0100] Cu 2+ Recovery: Add 1 mL of 0.35 mol / L Na2S solution to 20 mL of the purified solution, shake rapidly for 1 min, stir for 10 min, and let stand for 20 min; vacuum filter, collect the filter residue (CuS, purity ≥92%), and retain the filtrate;

[0101] Pb 2+ Recovery: Add 1 mL of 0.35 mol / L Na₂S solution to the filtrate, repeat the shaking, stirring, and standing process; collect the filter residue (PbS, purity ≥90%) by vacuum filtration, and retain the filtrate; according to the time Cu 2+ First, Pb precipitates. 2+ Post-precipitation;

[0102] Al 3+ Recovery: Continue to add NaOH solution to adjust the pH to 5, stir for 10 min and let stand for 20 min; filter and collect the residue (Al(OH)3), retain the filtrate;

[0103] Mg 2+ Recovery: Continue to add NaOH solution to adjust the pH to 11, stir for 10 min and let stand for 20 min; filter and collect the residue (Mg(OH)2), retain the filtrate;

[0104] Ca 2+ Recovery: Finally, add NaOH solution to adjust the pH to 14, stir for 10 min and let stand for 20 min; filter and collect the residue (Ca(OH)2), retain the filtrate;

[0105] ③ Following the reaction sequence in step 3① and the amount of precipitant added and reaction time obtained in step ②, precipitate the impurity ions in the impurity removal solution and collect them.

[0106] Figure 1 This is a schematic diagram of the structure of the wet dual-sorting device of the present invention;

[0107] Figure 2The image shows the physical sample of insoluble ash obtained by gravity and magnetic dual separation in Example 1. In the image: (a) strongly magnetic small particles; (b) strongly magnetic large particles; (c) moderately magnetic small particles; (d) weakly magnetic small particles. It can be seen that the surface morphology of different parts is quite different, and the surface becomes more and more porous from front to back.

[0108] Particle size analysis: 0.5 g each of strongly magnetic small particles, strongly magnetic large particles, medium magnetic small particles, and weakly magnetic small particles were collected before and after the addition of impurity ions by precipitation. 5 mL of deionized water was added and ultrasonically dispersed for 10 min. The particle size distribution was measured using a laser particle size analyzer. Figure 3 The figure shows the particle size distribution of insoluble ash obtained by gravity and magnetic dual separation in Example 1. As can be seen from the figure, the particle size of the unstirred part is mostly distributed between 37 and 1002 μm, so it is not suitable as a catalyst for anaerobic alkane production. The iron oxide powders of strongly magnetic small particles, strongly magnetic large particles, and medium magnetic small particles are fine, with particle sizes between 1.42 and 502 μm, 2.24 and 6.32 μm, and 0.36 and 632 μm, respectively.

[0109] Figure 4 XRD patterns of strongly magnetic large particles (QD), strongly magnetic small particles (QX), and medium magnetic small particles (ZX) after impurity removal are shown; X-ray diffraction (XRD) was performed on iron oxides in different locations. Figure 4 It can be seen that the main component of insoluble ash is Fe2O3;

[0110] Figure 5 The removal rates of impurity ions at different locations corresponding to strongly magnetic small particles, strongly magnetic large particles, medium magnetic small particles, and weakly magnetic small particles are shown. It can be seen that the average removal rate of the main impurities copper, lead, calcium, and magnesium can all reach ≥90%.

[0111] Figure 6 Comparison of ion recovery rates after collection of impurity ion precipitation; the recovery rates of high-valence impurity ions copper and lead in the solution are ≥95%.

[0112] Figure 7 This is a particle size distribution diagram of strongly magnetic small particles, strongly magnetic large particles, medium magnetic small particles, and weakly magnetic small particles after impurity removal by dilute hydrochloric acid; and... Figure 3 The comparison shows that the particle size tends to be consistent before and after purification with dilute hydrochloric acid;

[0113] Elemental content analysis: Referring to the digestion process and ICP detection method described above, the elemental content of strongly magnetic small particles, strongly magnetic large particles, moderately magnetic small particles, and weakly magnetic small particles before and after collection of impurity ions by precipitation was determined. Table 1 shows the changes in ion content and ion recovery rate corresponding to strongly magnetic large particles (QD), strongly magnetic small particles (QX), and moderately magnetic small particles (ZX).

[0114] Table 1

[0115]

Claims

1. A method for recovering micron-sized iron oxide particles and impurity ions from sintering die head ash using a wet dual-separation device, characterized in that: The method for recovering micron-sized iron oxide particles and impurity ions from sintering die head ash using a wet dual-separation device is carried out according to the following steps: Step 1: Gravity and Magnetic Dual Separation Extract the insoluble ash from the sintering machine head ash, transfer the insoluble ash to the stirring tank (1), fill the sorting chamber of the gravity and magnetic dual sorting device with water, and return the effluent from the three-stage sedimentation chamber (5) to the stirring tank (1) through the pipe (8), and turn on the agitator (6) to make the material in the stirring tank (1) fluidized; the material in the sorting chamber passes through each sedimentation chamber in sequence and achieves the sorting of insoluble ash, and finally collects the insoluble ash in each sedimentation chamber and dries it; the insoluble ash includes strongly magnetic small particles, strongly magnetic large particles, medium magnetic small particles, and weakly magnetic small particles; The magnetic interception chamber (2) is used to collect strongly magnetic small particles; the intercepting plate (12) between the magnetic interception chamber (2) and the primary sedimentation chamber (3) can be used to adjust the water flow rate, which is set to 0.5~5 cm / s; The primary sedimentation chamber (3) is used to collect large, strongly magnetic particles. The insoluble ash flows through the primary sedimentation chamber (3) for 3 to 30 seconds. The secondary sedimentation chamber (4) is used to collect small magnetic particles; the insoluble ash flows through the secondary sedimentation chamber (4) for 3~30s; The three-stage sedimentation chamber (5) is used to collect weakly magnetic small particles; the insoluble ash flows through the three-stage sedimentation chamber (5) for 10~100s; The particulate matter content in the effluent from the three-stage sedimentation chamber (5) is below 100 mg / L; the effluent is returned to the mixing tank (1) through the pipe (8). The gravity-magnetic dual separation device consists of a mixing tank (1) and a separation chamber; the separation chamber includes a magnetic interception chamber (2), a primary sedimentation chamber (3), a secondary sedimentation chamber (4), and a tertiary sedimentation chamber (5) arranged sequentially; the mixing tank (1) is located on the feed side of the magnetic interception chamber (2), and a stirrer (6) is installed inside the mixing tank (1); a magnet (7) is installed on the side of the magnetic interception chamber (2) below the mixing tank (1); the outlet of the tertiary sedimentation chamber (5) is connected to the inlet of the mixing tank (1) through a pipe (8); a top material passage is provided on the upper part of the partition between the magnetic interception chamber (2) and the mixing tank (1), and between the magnetic interception chamber (2) and the primary sedimentation chamber (3), and between the primary sedimentation chamber (3) and the... A baffle plate (12) is provided between the secondary sedimentation chambers (4) and between the secondary sedimentation chamber (4) and the tertiary sedimentation chamber (5). The upper end of the baffle plate (12) is connected to the top of the sorting chamber, and the lower end of the baffle plate is provided with a bottom material passage. A first overflow plate (9) is provided on the water inlet side of the baffle plate between the primary sedimentation chamber (3) and the secondary sedimentation chamber (4). A second overflow plate (10) is provided on the water inlet side of the baffle plate between the secondary sedimentation chamber (4) and the tertiary sedimentation chamber (5). A third overflow plate (11) is provided on the water outlet side of the tertiary sedimentation chamber (5). The bottoms of the first overflow plate (9), the second overflow plate (10) and the third overflow plate (11) are fixed to the bottom plate of the sorting chamber, and the upper ends of the first overflow plate (9), the second overflow plate (10) and the third overflow plate (11) are all higher than the lower end of the baffle plate. Step 2: Separation and removal of iron oxide particles ① The insoluble ash is digested to obtain a solution of insoluble ash, and the types and contents of impurities in the solution are determined to clarify the composition of the entire insoluble ash. ② The insoluble ash obtained from the magnetic retention chamber (2) and the precipitation chamber is eluted with an eluent and then separated into solid and liquid to obtain a cleaned liquid and iron oxide particles. The types and contents of impurities in the cleaned liquid are determined and compared with the types and contents of impurities measured in the digestion solution in step 2 ①. If the content of impurities in the cleaned liquid is lower than the measured value in step 2 ①, the elution time is increased and the concentration of the eluent is increased until the content of impurities in the cleaned liquid is not lower than the measured value in step 2 ①. Step 3: Collect impurity ions in the impurity removal solution by precipitation. ① The order of precipitation reaction between the precipitant and impurity ions in the purification solution and the theoretical amount of precipitant added were simulated using HYDRA / MEDUSA software; ② Following the reaction sequence obtained from the simulation, the precipitant and impurity removal solution were reacted until the impurity ions were completely precipitated, verifying the amount of precipitant added and obtaining the reaction time; ③ Following the reaction sequence in step 3① and the amount of precipitant added and reaction time obtained in step ②, precipitate the impurity ions in the impurity removal solution and collect them.

2. The method for recovering micron-sized iron oxide particles and impurity ions from sintering machine head ash using a wet dual-separation device according to claim 1, characterized in that: Step 1: The height of the first overflow plate (9) and the second overflow plate (10) is 20%-50% of the height of the third overflow plate (11); the distance between the lower end of the intercepting plate (12) and the bottom of the sorting chamber is 10%-20% of the height of the sorting chamber.

3. The method for recovering micron-sized iron oxide particles and impurity ions from sintering machine head ash using a wet dual-separation device according to claim 1, characterized in that: The extraction process of insoluble ash in step one is as follows: take the ash from the sintering machine head to be treated, add water to dissolve it, then filter to remove soluble salts, and collect the filter residue as insoluble ash.

4. The method for recovering micron-sized iron oxide particles and impurity ions from sintering machine head ash using a wet dual-separation device according to claim 1, characterized in that: The stirring speed of the stirrer (6) mentioned in step one is 100-500 rpm.

5. The method for recovering micron-sized iron oxide particles and impurity ions from sintering machine head ash using a wet dual-separation device according to claim 1, characterized in that: The magnetic trapping chamber (2) described in step one is equipped with a guide plate (13), which is a stepped or inclined plate.

6. The method for recovering micron-sized iron oxide particles and impurity ions from sintering mill head ash using a wet dual-separation device according to claim 1, characterized in that: Step 2① The digestion process is as follows: Take the dried insoluble ash and place it in a polytetrafluoroethylene crucible. Add concentrated hydrochloric acid, concentrated nitric acid, hydrofluoric acid, and perchloric acid, and heat the crucible to 100~220℃. The ratio of concentrated hydrochloric acid, concentrated nitric acid, hydrofluoric acid, and perchloric acid to insoluble ash is 1~8mL:0.2g. The mass fraction of concentrated hydrochloric acid is 30%~35%, the mass fraction of concentrated nitric acid is 60~65%, the mass fraction of hydrofluoric acid is 35~40%, and the mass fraction of perchloric acid is 65~72%.

7. The method for recovering micron-sized iron oxide particles and impurity ions from sintering machine head ash using a wet dual-separation device according to claim 1, characterized in that: The eluent in step 2② is one or a mixture of two of dilute hydrochloric acid and dilute nitric acid in any proportion, and the concentration of the eluent is 0.1-1 mol / L.

8. The method for recovering micron-sized iron oxide particles and impurity ions from sintering machine head ash using a wet dual-separation device according to claim 1, characterized in that: Step 2① The process for determining the types and contents of impurity ions in the solution is as follows: dilute the solution with water, and determine the types and contents of each ion in the solution by inductively coupled plasma atomic emission spectrometry.

9. The method for recovering micron-sized iron oxide particles and impurity ions from sintering machine head ash using a wet dual-separation device according to claim 1, characterized in that: The process for determining the content of impurity ions in the impurity removal solution in step 2② is as follows: dilute the impurity removal solution with water, and determine the content of each ion in the solution by inductively coupled plasma atomic emission spectrometry.

10. The method for recovering micron-sized iron oxide particles and impurity ions from sintering mill head ash using a wet dual-separation device according to claim 1, characterized in that: The precipitant mentioned in step three is one or both of sodium hydroxide and sodium sulfide.

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