Preparation method of superfine high-dispersion ferric hydroxide
Ultrafine, highly dispersed ferric hydroxide was prepared by emulsifying the interfacial reaction between ferric stearate and urea solution, which solved the agglomeration problem and achieved high dispersibility and uniform particle size. At the same time, resources were recycled, reducing wastewater generation.
Patent Information
- Application Number
- CN202511391271.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-26
- Publication Date
- 2026-02-24
AI Technical Summary
Existing technologies make it difficult to prepare highly dispersed ultrafine ferric hydroxide, and its small solubility product leads to agglomeration, making it difficult to obtain highly dispersed powder.
By emulsifying ferric stearate with urea solution, the urea decomposes at high temperature to generate carbon dioxide and ammonia. The ammonia reacts with ferric stearate at the interface, and the combination of the interface reaction and homogeneous precipitation produces ultrafine, highly dispersed ferric hydroxide, while recycling stearate and ammonium ions.
This method achieves high dispersibility and uniform particle size of ultrafine ferric hydroxide, and features a simple process with low wastewater generation, enabling resource recycling.
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Figure CN121553992A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing ultrafine, highly dispersed ferric hydroxide, belonging to the field of materials technology. Background Technology
[0002] Ferric hydroxide, also known as high-temperature ferric hydroxide, has the chemical formula Fe(OH)3 and a molecular weight of 106.87. It is a brown cubic crystal or brown flocculent precipitate. Heating to above 500℃ dehydrates it into ferric oxide. It is insoluble in water, ethanol, and ether; freshly prepared ferric hydroxide is readily soluble in inorganic and organic acids, but becomes difficult to dissolve upon aging. It can be fused with sodium carbonate to yield sodium ferrate.
[0003] It is mainly used as a purifying agent and absorbent, and is used in the manufacture of pigments, medicines, and antidotes for arsenic poisoning.
[0004] Ultrafine ferric hydroxide can be used as a basic raw material for preparing ultrafine ferric oxide red and other iron salts, ultrafine iron powder, etc. Because the solubility product of ferric hydroxide is very small, it is particularly easy to agglomerate and it is not easy to obtain highly dispersed powder. Summary of the Invention
[0005] In view of this, the present invention provides a method for preparing ultrafine, highly dispersed ferric hydroxide. By emulsification, ferric stearate and urea solution are mixed and emulsified to obtain an emulsion. Then, urea is decomposed at high temperature, and the resulting carbon dioxide is released. The resulting ammonia gas is dissolved in water to obtain ammonia water, which then reacts with ferric stearate at the interface to obtain highly dispersed and uniformly sized ultrafine ferric hydroxide. The process of the present invention is simple and realizes the recycling of stearate ions, as well as the resource utilization of chloride ions and ammonium ions.
[0006] The present invention solves the above-mentioned technical problems through the following technical means:
[0007] A method for preparing ultrafine, highly dispersed ferric hydroxide comprises the following steps:
[0008] (1) Add the ferric stearate-turpentine oil solution to the urea-polyethylene glycol solution. The molar ratio of ferric stearate to urea is 1:1.6-1.8. Then add the surfactant and keep the temperature constant to 20-35℃. Then stir at a stirring speed of 700-900r / min for 30-60min to obtain an emulsion.
[0009] (2) Heat the emulsion to 95-105℃ and react at this temperature for 3-4 hours. The resulting material is then separated into solid and liquid by centrifugation.
[0010] (3) The solid was washed with alcohol to obtain washing liquid and washing residue;
[0011] (4) After the washing residue is vacuum dried, it is air-jet pulverized and the pulverized material is sieved to obtain ultrafine highly dispersed ferric hydroxide.
[0012] The iron stearate-turpentine oil solution contains 10-20% iron stearate by mass, the urea-polyethylene glycol solution contains 1.5-2.5 mol / L urea and 0.1-0.2 mol / L polyethylene glycol by concentration, the surfactant is an HLB value of 3-18, and the surfactant concentration in the emulsion is 0.02-0.05 mol / L. The stirring is performed using an emulsifying dispersion stirrer.
[0013] The stirring speed in step (2) is 400-600 r / min.
[0014] In step (2), the solid-liquid separation yields a liquid. A 1.5-2.5 mol / L ferric chloride solution is added, and the mixture is stirred to obtain a ferric stearate-turpentine organic solution. This solution is then returned to step (1) for use. The remaining aqueous phase is concentrated and crystallized to obtain ammonium chloride crystals.
[0015] In step (3), the solid is washed with alcohol until the mass concentration of ammonium stearate in the solid is less than 150 ppm. The washing liquid is then distilled under reduced pressure to evaporate the alcohol, which is then condensed and reused. The remaining solution is returned to be mixed with the liquid obtained from the solid-liquid separation in step (2) for further processing.
[0016] In step (4), the washing residue is dried until the free water mass fraction is less than 200 ppm and then the drying is stopped. The air jet pulverization process is carried out by a classifying wheel. The pulverized material is passed through a 200-300 mesh sieve by an ultrasonic vibrating screen and vacuum packaged to obtain ultrafine highly dispersed ferric hydroxide.
[0017] The ratio of the molar amounts of ammonium stearate to added ferric chloride in the liquid obtained by solid-liquid separation is 3:1.01-1.02.
[0018] This process involves emulsifying a ferric stearate-turpentine oil solution with a urea-polyethylene glycol solution to form an emulsion. This creates a large interface between the organic and liquid phases. Then, at high temperature, the urea decomposes to produce carbon dioxide and ammonia. The carbon dioxide, being insoluble in water, escapes, while the ammonia dissolves in water, yielding ammonia water. This ammonia water then reacts with ferric stearate at the interface between the organic and aqueous phases, producing ultrafine and highly dispersible ferric hydroxide particles. Furthermore, the resulting ammonium stearate can be recycled; by adding ferric chloride, ferric stearate and ammonium chloride can be obtained.
[0019] This invention ingeniously combines interfacial reaction with homogeneous precipitation, decomposing urea at high temperature in an emulsified state. The resulting ammonia water then reacts with ferric stearate, avoiding local over-concentration while achieving high dispersion, thus obtaining ultrafine, highly dispersed ferric hydroxide.
[0020] The process of this invention is short and generates very little wastewater.
[0021] The beneficial effects of this invention are: the process is simple, and it realizes the recycling of stearate ions, as well as the resource utilization of chloride ions and ammonium ions. At the same time, the obtained ferric hydroxide has good dispersibility, small particles, and relatively uniform particle size. Attached Figure Description
[0022] Appendix Figure 1 This is a SEM image of ferric hydroxide obtained in Example 1 of the present invention.
[0023] Appendix Figure 2 This is a SEM image of ferric hydroxide obtained in Example 2 of the present invention.
[0024] Appendix Figure 3 This is a SEM image of ferric hydroxide obtained in Example 3 of the present invention.
[0025] Appendix Figure 4 This is a particle size distribution diagram of ferric hydroxide obtained in Example 1 of the present invention. Detailed Implementation
[0026] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment describes a method for preparing ultrafine, highly dispersed ferric hydroxide, which includes the following steps:
[0027] (1) Add the ferric stearate-turpentine oil solution to the urea-polyethylene glycol solution. The molar ratio of ferric stearate to urea is 1:1.6-1.8. Then add the surfactant and keep the temperature constant to 20-35℃. Then stir at a stirring speed of 700-900r / min for 30-60min to obtain an emulsion.
[0028] (2) Heat the emulsion to 95-105℃ and react at this temperature for 3-4 hours. The resulting material is then separated into solid and liquid by centrifugation.
[0029] (3) The solid was washed with alcohol to obtain washing liquid and washing residue;
[0030] (4) After the washing residue is vacuum dried, it is air-jet pulverized and the pulverized material is sieved to obtain ultrafine highly dispersed ferric hydroxide.
[0031] The iron stearate-turpentine oil solution contains 10-20% iron stearate by mass, the urea-polyethylene glycol solution contains 1.5-2.5 mol / L urea and 0.1-0.2 mol / L polyethylene glycol by concentration, the surfactant is an HLB value of 3-18, and the surfactant concentration in the emulsion is 0.02-0.05 mol / L. The stirring is performed using an emulsifying dispersion stirrer.
[0032] The stirring speed in step (2) is 400-600 r / min.
[0033] In step (2), the solid-liquid separation yields a liquid. A 1.5-2.5 mol / L ferric chloride solution is added, and the mixture is stirred to obtain a ferric stearate-turpentine organic solution. This solution is then returned to step (1) for use. The remaining aqueous phase is concentrated and crystallized to obtain ammonium chloride crystals.
[0034] In step (3), the solid is washed with alcohol until the mass concentration of ammonium stearate in the solid is less than 150 ppm. The washing liquid is then distilled under reduced pressure to evaporate the alcohol, which is then condensed and reused. The remaining solution is returned to be mixed with the liquid obtained from the solid-liquid separation in step (2) for further processing.
[0035] In step (4), the washing residue is dried until the free water mass fraction is less than 200 ppm and then the drying is stopped. The air jet pulverization process is carried out by a classifying wheel. The pulverized material is passed through a 200-300 mesh sieve by an ultrasonic vibrating screen and vacuum packaged to obtain ultrafine highly dispersed ferric hydroxide.
[0036] The ratio of the molar amounts of ammonium stearate to added ferric chloride in the liquid obtained by solid-liquid separation is 3:1.01-1.02.
[0037] Example 1
[0038] A method for preparing ultrafine, highly dispersed ferric hydroxide, characterized by the following steps:
[0039] (1) Add the ferric stearate-turpentine solution to the urea-polyethylene glycol solution. The molar ratio of ferric stearate to urea is 1:1.65. Then add the surfactant and keep the temperature constant to 24°C. Then stir for 30 minutes at a stirring speed of 900 r / min to obtain an emulsion.
[0040] (2) The emulsion is heated to 100°C and reacted at this temperature for 3.5 hours. The resulting material is then separated into solid and liquid by centrifugation.
[0041] (3) The solid was washed with alcohol to obtain washing liquid and washing residue;
[0042] (4) After the washing residue is vacuum dried, it is air-jet pulverized and the pulverized material is sieved to obtain ultrafine highly dispersed ferric hydroxide.
[0043] The iron stearate-turpentine oil solution contains 10% iron stearate by mass, the urea-polyethylene glycol solution contains 2.5 mol / L urea and 0.15 mol / L polyethylene glycol, the surfactant is an HLB value of 6.5, and the surfactant concentration in the emulsion is 0.04 mol / L. The stirring is performed using an emulsifying dispersion stirrer.
[0044] The stirring speed in step (2) is 500 r / min.
[0045] In step (2), the solid-liquid separation yields a liquid. A 2.5 mol / L ferric chloride solution is added, and the mixture is stirred to obtain a ferric stearate-turpentine organic solution, which is then returned to step (1) for use. The remaining aqueous phase is concentrated and crystallized to obtain ammonium chloride crystals.
[0046] In step (3), the solid is washed with alcohol until the mass concentration of ammonium stearate in the solid is less than 150 ppm. The washing liquid is then distilled under reduced pressure to evaporate the alcohol, which is then condensed and reused. The remaining solution is returned to be mixed with the liquid obtained from the solid-liquid separation in step (2) for further processing.
[0047] In step (4), the washing residue is dried until the free water mass fraction is less than 200 ppm and then the drying is stopped. The air jet pulverization process is carried out by a classifying wheel. The pulverized material is passed through a 200-mesh ultrasonic vibrating screen and vacuum packaged to obtain ultrafine highly dispersed ferric hydroxide.
[0048] The ratio of the molar amounts of ammonium stearate to added ferric chloride in the liquid obtained by solid-liquid separation was 3:1.015.
[0049] The final test results for the ferric hydroxide product are as follows:
[0050]
[0051] like Figure 1 The image shows the SEM of the product obtained in this embodiment. From the SEM, it can be seen that the particles are spherical or near-spherical with a very small primary particle size, basically around 100nm, and have good dispersibility.
[0052] from Figure 4 As shown, this is the particle size distribution diagram of the product obtained in this embodiment. The D50 is 0.463μm, and the particle size distribution is very narrow and highly concentrated.
[0053] Example 2
[0054] A method for preparing ultrafine, highly dispersed ferric hydroxide, characterized by the following steps:
[0055] (1) Add the ferric stearate-turpentine solution to the urea-polyethylene glycol solution. The molar ratio of ferric stearate to urea is 1:1.6. Then add the surfactant, keep the temperature constant to 35°C, and then stir for 60 min at a stirring speed of 900 r / min to obtain an emulsion.
[0056] (2) The emulsion was heated to 105°C and reacted at this temperature for 4 hours. The resulting material was then separated into solid and liquid by centrifugation.
[0057] (3) The solid was washed with alcohol to obtain washing liquid and washing residue;
[0058] (4) After the washing residue is vacuum dried, it is air-jet pulverized and the pulverized material is sieved to obtain ultrafine highly dispersed ferric hydroxide.
[0059] The iron stearate-turpentine oil solution contains 20% iron stearate by mass, the urea-polyethylene glycol solution contains 2.5 mol / L urea and 0.2 mol / L polyethylene glycol, the surfactant is an HLB value of 18, the surfactant concentration in the emulsion is 0.05 mol / L, and the stirring is performed using an emulsifying dispersion stirrer.
[0060] The stirring speed in step (2) is 600 r / min.
[0061] In step (2), the solid-liquid separation yields a liquid. A 2.5 mol / L ferric chloride solution is added, and the mixture is stirred to obtain a ferric stearate-turpentine organic solution, which is then returned to step (1) for use. The remaining aqueous phase is concentrated and crystallized to obtain ammonium chloride crystals.
[0062] In step (3), the solid is washed with alcohol until the mass concentration of ammonium stearate in the solid is less than 150 ppm. The washing liquid is then distilled under reduced pressure to evaporate the alcohol, which is then condensed and reused. The remaining solution is returned to be mixed with the liquid obtained from the solid-liquid separation in step (2) for further processing.
[0063] In step (4), the washing residue is dried until the free water mass fraction is less than 200 ppm and then the drying is stopped. The air jet pulverization process is carried out by a classifying wheel. The pulverized material is passed through a 300-mesh ultrasonic vibrating screen and vacuum packaged to obtain ultrafine highly dispersed ferric hydroxide.
[0064] The ratio of the molar amounts of ammonium stearate to added ferric chloride in the liquid obtained by solid-liquid separation was 3:1.01.
[0065] The final test results for the ferric hydroxide product are as follows:
[0066]
[0067] like Figure 2 The image shows the SEM of the product obtained in this embodiment. From the SEM, it can be seen that the particles are spherical or near-spherical with a very small primary particle size, basically around 100nm, and have good dispersibility.
[0068] Example 3
[0069] A method for preparing ultrafine, highly dispersed ferric hydroxide, characterized by the following steps:
[0070] (1) Add the ferric stearate-turpentine solution to the urea-polyethylene glycol solution. The molar ratio of ferric stearate to urea is 1:1.8. Then add the surfactant, keep the temperature constant to 20°C, and then stir for 30 min at a stirring speed of 900 r / min to obtain an emulsion.
[0071] (2) The emulsion was heated to 95°C and reacted at this temperature for 3 hours. The resulting material was then separated into solid and liquid by centrifugation.
[0072] (3) The solid was washed with alcohol to obtain washing liquid and washing residue;
[0073] (4) After the washing residue is vacuum dried, it is air-jet pulverized and the pulverized material is sieved to obtain ultrafine highly dispersed ferric hydroxide.
[0074] The iron stearate-turpentine oil solution contains 10% iron stearate by mass, the urea-polyethylene glycol solution contains 1.5 mol / L urea and 0.1 mol / L polyethylene glycol, the surfactant is an HLB value of 3, the surfactant concentration in the emulsion is 0.02 mol / L, and the stirring is performed using an emulsification dispersion stirrer.
[0075] The stirring speed in step (2) is 400 r / min.
[0076] In step (2), the solid-liquid separation yields a liquid. A 1.5 mol / L ferric chloride solution is added, and the mixture is stirred to obtain a ferric stearate-turpentine organic solution, which is then returned to step (1) for use. The remaining aqueous phase is concentrated and crystallized to obtain ammonium chloride crystals.
[0077] In step (3), the solid is washed with alcohol until the mass concentration of ammonium stearate in the solid is less than 150 ppm. The washing liquid is then distilled under reduced pressure to evaporate the alcohol, which is then condensed and reused. The remaining solution is returned to be mixed with the liquid obtained from the solid-liquid separation in step (2) for further processing.
[0078] In step (4), the washing residue is dried until the free water mass fraction is less than 200 ppm and then the drying is stopped. The air jet pulverization process is carried out by a classifying wheel. The pulverized material is passed through a 200-mesh ultrasonic vibrating screen and vacuum packaged to obtain ultrafine highly dispersed ferric hydroxide.
[0079] The ratio of the molar amounts of ammonium stearate to added ferric chloride in the liquid obtained by solid-liquid separation was 3:1.01.
[0080] The final test results for the ferric hydroxide product are as follows:
[0081]
[0082] like Figure 3 The image shows the SEM of the product obtained in this embodiment. From the SEM, the particles are spherical or near-spherical with a very small primary particle size, basically around 120 nm, and have good dispersibility.
[0083] The ferric hydroxide from Example 1 was reduced with hydrogen at a temperature of 480°C for 6 hours, followed by air jet milling under nitrogen protection. The resulting iron powder test data are as follows:
[0084]
[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.
Claims
1. A method for preparing ultrafine, highly dispersed ferric hydroxide, characterized in that, The following steps are required: (1) Add the ferric stearate-turpentine oil solution to the urea-polyethylene glycol solution. The molar ratio of ferric stearate to urea is 1:1.6-1.
8. Then add the surfactant and keep the temperature constant to 20-35℃. Then stir at a stirring speed of 700-900r / min for 30-60min to obtain an emulsion. (2) Heat the emulsion to 95-105℃ and react at this temperature for 3-4 hours. The resulting material is then separated into solid and liquid by centrifugation. (3) The solid was washed with alcohol to obtain washing liquid and washing residue; (4) After the washing residue is vacuum dried, it is air-jet pulverized and the pulverized material is sieved to obtain ultrafine highly dispersed ferric hydroxide.
2. The method for preparing ultrafine, highly dispersed ferric hydroxide according to claim 1, characterized in that: The iron stearate-turpentine oil solution contains 10-20% iron stearate by mass, the urea-polyethylene glycol solution contains 1.5-2.5 mol / L urea and 0.1-0.2 mol / L polyethylene glycol by concentration, the surfactant is an HLB value of 3-18, and the surfactant concentration in the emulsion is 0.02-0.05 mol / L. The stirring is performed using an emulsifying dispersion stirrer.
3. The method for preparing ultrafine, highly dispersed ferric hydroxide according to claim 1, characterized in that: The stirring speed in step (2) is 400-600 r / min.
4. The method for preparing ultrafine, highly dispersed ferric hydroxide according to claim 3, characterized in that: In step (2), the solid-liquid separation yields a liquid. A 1.5-2.5 mol / L ferric chloride solution is added, and the mixture is stirred to obtain a ferric stearate-turpentine organic solution. This solution is then returned to step (1) for use. The remaining aqueous phase is concentrated and crystallized to obtain ammonium chloride crystals.
5. The method for preparing ultrafine, highly dispersed ferric hydroxide according to claim 1, characterized in that: In step (3), the solid is washed with alcohol until the mass concentration of ammonium stearate in the solid is less than 150 ppm. The washing liquid is then distilled under reduced pressure to evaporate the alcohol, which is then condensed and reused. The remaining solution is returned to be mixed with the liquid obtained from the solid-liquid separation in step (2) for further processing.
6. The method for preparing ultrafine, highly dispersed ferric hydroxide according to claim 1, characterized in that: In step (4), the washing residue is dried until the free water mass fraction is less than 200 ppm and then the drying is stopped. The air jet pulverization process is carried out by a classifying wheel. The pulverized material is passed through a 200-300 mesh sieve by an ultrasonic vibrating screen and vacuum packaged to obtain ultrafine highly dispersed ferric hydroxide.
7. The method for preparing ultrafine, highly dispersed ferric hydroxide according to claim 4, characterized in that: The ratio of the molar amounts of ammonium stearate to added ferric chloride in the liquid obtained by solid-liquid separation is 3:1.01-1.02.