Methods for treating red mud
By combining sodium removal with sulfuric acid solution and multi-step leaching to treat red mud, the environmental hazards and resource recovery problems of red mud have been solved, and the efficient separation of valuable metals and the preparation of compounds have been achieved, thus achieving a balance between environmental benefits and resource value.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- YUNXI WENSHAN ZINC INDIUM SMELTING CO LTD
- Filing Date
- 2026-04-13
- Publication Date
- 2026-06-26
AI Technical Summary
The accumulation of red mud harms the environment, and existing treatment technologies are costly, prone to causing secondary pollution, and difficult to effectively recover valuable metals.
Red mud was treated with sulfuric acid solution to remove sodium, followed by first-stage and second-stage leaching treatments. Combined with steps such as sulfur dioxide reduction, ferrous carbonate precipitation of titanium, ammonia precipitation of aluminum, and oxygen precipitation of iron, valuable metals such as iron, aluminum, and titanium were separated and recovered. Sodium sulfate and ammonium sulfate were prepared by crystallization.
The method effectively treats red mud, recovers valuable metals such as iron, aluminum, and titanium, and prepares compounds with application value. The treatment process is simple and easy to control.
Smart Images
Figure CN122279221A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of hydrometallurgical technology, and more specifically, to a method for treating red mud. Background Technology
[0002] Red mud is a highly alkaline solid waste generated during the Bayer process, sintering process, or combined process for alumina production. Approximately 0.8 to 2.5 tons of red mud are produced for every ton of alumina produced. Bayer process red mud has a high iron content (around 30%), while sintering process red mud is primarily composed of aluminum and calcium (over 60%). The main components of red mud include Al₂O₃, Fe₂O₃, CaO, and Na₂O, with Fe₂O₃ content reaching 30% (Bayer process) or 10% (sintering process).
[0003] The environmental hazards caused by the accumulation of red mud cannot be ignored. Open-air storage of red mud requires a large area of land. Red mud is highly alkaline (pH value of 10~12.5), which can lead to soil salinization and groundwater pollution. The heavy metals it contains (such as Cd and Pb) have potential ecotoxicity, and particulate dust threatens air quality.
[0004] It should be noted that the above statements are only used to provide background information related to this application and do not necessarily constitute prior art. Summary of the Invention
[0005] In a first aspect of this application, a method for treating red mud is proposed, comprising: subjecting red mud to a sulfuric acid solution for sodium removal to obtain a sodium sulfate washing solution and sodium removal residue; subjecting the sodium removal residue to a first-stage leaching treatment to obtain a first-stage leachate and a first-stage leaching residue; subjecting the first-stage leaching residue to a second-stage leaching treatment to obtain a second-stage leachate and a second-stage leaching residue, wherein the second-stage leaching residue includes iron-calcium slag; introducing sulfur dioxide into the first-stage leachate for reduction treatment to obtain a reduced solution; subjecting the reduced solution to ferrous carbonate for titanium precipitation treatment to obtain a titanium-precipitated solution and titanium slag; subjecting the titanium-precipitated solution to ammonia water for aluminum precipitation treatment to obtain an aluminum-precipitated solution and aluminum hydroxide slag; and introducing oxygen into the aluminum-precipitated solution for iron precipitation treatment to obtain hematite slag and an iron-precipitated solution.
[0006] In some embodiments, at least one of the following conditions is met: the endpoint pH value of the desodium treatment is 4.8 to 5.0; the temperature of the desodium treatment is 80°C to 90°C; and the liquid-to-solid ratio of the desodium treatment is 2L / kg to 3L / kg.
[0007] In some embodiments, at least one of the following conditions is met: the final acidity of the first-stage leaching treatment is 10 g / L to 20 g / L; the temperature of the first-stage leaching treatment is 80°C to 90°C; the liquid-to-solid ratio of the first-stage leaching treatment is 4 L / kg to 6 L / kg; the final acidity of the second-stage leaching treatment is 140 g / L to 150 g / L; the liquid-to-solid ratio of the second-stage leaching treatment is 8 L / kg to 8 L / kg; and the temperature of the second-stage leaching treatment is 80°C to 90°C.
[0008] In some embodiments, at least one of the following conditions is met: the temperature of the reduction treatment is 70°C to 85°C; the time of the reduction treatment is 30 min to 60 min; and the excess sulfur dioxide coefficient of the reduction treatment is 1.2 to 1.4.
[0009] In some embodiments, at least one of the following conditions is met: the temperature of the titanium precipitation treatment is 90℃~100℃; the final pH value of the titanium precipitation treatment is 2.8~3.0; the final pH value of the aluminum precipitation treatment is 4.5~5.5; the temperature of the aluminum precipitation treatment is 70℃~85℃; the temperature of the iron precipitation treatment is 165℃~175℃; and the final acidity of the iron precipitation treatment is 25g / L~30g / L.
[0010] The mixing temperature is 15℃~25℃; the excess ammonium carbonate coefficient of the mixing process is 1.2~1.5.
[0011] In some embodiments, the method further includes: subjecting the second-stage leachate to the sodium-removing residue for the first-stage leaching treatment.
[0012] In some embodiments, the method further includes: performing a first crystallization treatment on the sodium sulfate washing solution to obtain sodium sulfate and a first mother liquor, wherein the evaporation temperature of the first crystallization treatment is 105°C to 110°C, and the crystallization temperature of the first crystallization treatment is 20°C to 30°C; and mixing the first mother liquor with the sulfuric acid solution to perform the sodium removal treatment.
[0013] In some embodiments, the method further includes: mixing ammonium carbonate with the aluminum precipitation solution to obtain the ferrous carbonate and ammonium sulfate solution, wherein the mixing temperature is 15°C to 25°C and the excess ammonium carbonate coefficient of the mixing is 1.2 to 1.5.
[0014] In some embodiments, the method further includes: performing a second crystallization treatment on the ammonium sulfate solution to obtain ammonium sulfate and a second mother liquor, wherein the evaporation temperature of the second crystallization treatment is 80°C to 110°C and the crystallization temperature of the second crystallization treatment is 15°C to 25°C; and mixing the second mother liquor with the aluminum precipitation liquid to perform the mixing treatment.
[0015] In some embodiments, the method further includes: washing the second-stage leaching residue to obtain the iron-calcium slag, wherein the liquid-to-solid ratio of the washing treatment is 3L / kg to 4L / kg, and the temperature of the washing treatment is 40℃ to 60℃.
[0016] The beneficial effects of the technical solution proposed in this application include at least the following: The method of this application not only achieves effective treatment of red mud, but also recovers valuable metals such as iron, aluminum, and titanium from red mud and prepares compounds such as ammonium sulfate and sodium sulfate with application value, making full use of the metal resources in red mud and the treatment process is simple and easy to control. Attached Figure Description
[0017] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a process flow diagram of one embodiment of this application. Detailed Implementation
[0018] The embodiments of this application are described in detail below, with examples of these embodiments shown in the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.
[0019] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit this application; unless otherwise stated, the values of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).
[0020] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are open-ended expressions, meaning they include what is specified in this application but do not exclude other aspects.
[0021] In the description of this application, all figures disclosed herein, whether or not the words "approximately" or "about" are used, are approximate values. Each figure may vary by less than 10% or by a difference that is considered reasonable by one of the art, such as 1%, 2%, 3%, 4%, or 5%.
[0022] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values of 1 and 2 are listed, and if maximum range values of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
[0023] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.
[0024] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.
[0025] Currently, the treatment and resource utilization of red mud faces significant challenges: Alkali metals such as sodium and potassium exist in weakly bound states in red mud, making traditional water washing and acid leaching methods costly and prone to secondary pollution. The coexistence of multiple metals (such as Fe, Al, Ti, and rare earth elements) in red mud makes separation difficult, and the presence of non-magnetic iron minerals (such as hematite) limits beneficiation efficiency. The high alkali content in red mud restricts its dosage in cement (national standards require cement Na2O < 0.6%), while related technologies for red mud recycling (such as rotary hearth furnace reduction and microcrystalline glass preparation) have high industrialization costs, resulting in a comprehensive utilization rate of less than 5%.
[0026] Red mud remediation requires overcoming technical bottlenecks such as dealkali treatment and component separation, and combining multi-field collaborative innovation to achieve a balance between environmental benefits and resource value. Therefore, developing a method for efficiently treating red mud can not only significantly improve economic and environmental benefits, but also recover valuable metals from the red mud, turning them into by-products.
[0027] This application proposes a method for treating red mud, which not only achieves effective treatment of red mud, but also recovers metallic elements such as iron, aluminum, and titanium from the red mud, thereby maximizing resource utilization.
[0028] In the first aspect of this application, a method for treating red mud is proposed, with reference to Figure 1 ,include: S1: Red mud is subjected to sodium removal treatment with sulfuric acid solution to obtain sodium sulfate washing solution and sodium removal residue. In some embodiments, the method further includes: performing a first crystallization treatment on the sodium sulfate washing solution to obtain sodium sulfate and a first mother liquor, wherein the evaporation temperature of the first crystallization treatment is 105°C to 110°C, and the crystallization temperature of the first crystallization treatment is 20°C to 30°C; and mixing the first mother liquor with the sulfuric acid solution to perform the sodium removal treatment. This facilitates obtaining high-purity anhydrous sodium sulfate and recycling a portion of the sodium sulfate retained in the first mother liquor.
[0029] Sodium removal is achieved by mixing red mud and water, and then adding sulfuric acid solution to adjust the pH of the mixture to acidic. The main reaction occurring in the mixture is Na₂O + H₂SO₄ = Na₂SO₄ + H₂O. This converts sodium into sodium sulfate in the liquid phase. Subsequent treatment of the sodium sulfate washing solution yields high-purity sodium sulfate, thus achieving preliminary treatment of red mud and recovery of sodium from it.
[0030] In some embodiments, at least one of the following conditions is met: the endpoint pH value of the sodium removal treatment is 4.8 to 5.0; the temperature of the sodium removal treatment is 80°C to 90°C; and the liquid-to-solid ratio of the sodium removal treatment is 2 L / kg to 3 L / kg. This is beneficial for improving the sodium removal efficiency of the sodium removal treatment.
[0031] S2: The sodium-removing residue is subjected to a first-stage leaching treatment to obtain a first-stage leachate and a first-stage leaching residue. In some embodiments, the final acidity of the leaching process is 10 g / L to 20 g / L.
[0032] In some embodiments, sulfuric acid is subjected to a leaching treatment with the sodium removal residue.
[0033] The sodium-removing slag undergoes a first-stage leaching treatment. Under the action of an acidic solution, a large amount of elements such as aluminum, iron, and titanium in the sodium-removing slag enter the first-stage leaching solution.
[0034] The main reactions include: Al2O3+3H2SO4=Al2(SO4)3+3H2O, Fe2O3+3H2SO4=Fe2(SO4)3+3H2O, TiO2+2H2SO4=Ti(SO4)2+2H2O.
[0035] In some embodiments, the temperature of the first-stage leaching treatment is 80℃~90℃; the liquid-to-solid ratio of the first-stage leaching treatment is 4L / kg~6L / kg. Performing the first-stage leaching treatment under the aforementioned conditions ensures a suitable ion concentration in the slurry during the first-stage leaching of the desodium residue, which is beneficial for improving the filterability of the slurry and controlling the appropriate slurry throughput, and for facilitating the leaching of valuable metals such as aluminum, iron, and titanium from the desodium residue.
[0036] In some embodiments, the process further includes: subjecting the second-stage leachate and the sodium-removing residue to the first-stage leaching treatment. Thus, the second-stage leachate is returned to the first-stage leaching treatment, allowing for further utilization of the acids and elements such as aluminum, iron, and titanium contained in the second-stage leachate, thereby improving resource recovery rates and reducing emissions during the treatment process.
[0037] S3: Perform a second-stage leaching treatment on the first-stage leaching residue to obtain a second-stage leachate and a second-stage leaching residue, wherein the second-stage leaching residue includes iron-calcium slag. In the two-stage leaching process, the leaching residue from the first stage is mixed with dilute acid for leaching. By appropriately increasing the final acidity to the aforementioned range, unreacted valuable metals in the first-stage leaching residue can be further leached. This can reduce the content of unreacted valuable metals in the second-stage leaching residue and improve the purity of the iron-calcium slag in the second-stage leaching residue.
[0038] In some embodiments, the final acidity of the two-stage leaching treatment is 140 g / L to 150 g / L.
[0039] In some embodiments, the liquid-to-solid ratio of the two-stage leaching process is 8 L / kg to 8 L / kg; the temperature of the two-stage leaching process is 80℃ to 90℃. This helps to reduce the content of elements such as aluminum and iron in the two-stage leaching residue.
[0040] In some embodiments, the method further includes: washing the secondary leaching residue to obtain the iron-calcium slag, wherein the liquid-to-solid ratio of the washing treatment is 3 L / kg to 4 L / kg, and the washing temperature is 40°C to 60°C. The secondary leaching residue is mixed with water for washing to reduce the entrainment of soluble elements in the secondary leaching residue. The wash water is used to prepare dilute acid for secondary leaching, thereby facilitating the thorough removal of soluble elements from the secondary leaching residue and reducing entrainment.
[0041] S4: Sulfur dioxide is introduced into the leachate to perform reduction treatment, resulting in a reduced solution. The iron in a section of the leachate is mainly in the form of Fe. 3+ Sulfur dioxide exists in the form of sulfur dioxide, which is reduced by passing it into a leachate solution. The main reactions include: SO2 + 2H2O + 2Fe. 3+ =2Fe 2+ +SO4 2- +4H +Fe in a section of leachate 3+ Reduced to Fe 2+ This reduces the Fe content in the reduced solution. 3+ This increases the iron content and improves the efficiency of subsequent iron recovery.
[0042] In some embodiments, at least one of the following conditions is met: the temperature of the reduction treatment is 70°C to 85°C; the time of the reduction treatment is 30 min to 60 min; and the excess sulfur dioxide coefficient of the reduction treatment is 1.2 to 1.4. This is beneficial for improving the efficiency and effectiveness of the reduction treatment and increasing the Fe content in the solution. 2+ content.
[0043] S5: The reduced solution is subjected to titanium precipitation treatment with ferrous carbonate to obtain a titanium-precipitated solution and titanium slag. Ferrous carbonate was added to the reduced solution to adjust the pH value through a hydrolysis and neutralization reaction, thereby reducing the presence of titanium ions (Ti) in the liquid phase. 3+ The hydrolysis equilibrium of Ti shifts towards the formation of hydroxide precipitate. The reaction equation is: 3+ +3H₂O=Ti(OH)₃↓+3H + Therefore, titanium ions in the reduced solution can be converted into titanium hydroxide, thus realizing the recovery of titanium.
[0044] In some embodiments, the reduced solution is subjected to heat treatment. As a result, the titanium in the reduced solution is converted from the form of Ti(Ⅳ) to Ti(Ⅲ) through boiling hydrolysis.
[0045] In some embodiments, at least one of the following conditions is met: the temperature of the titanium precipitation treatment is 90°C to 100°C; and the final pH value of the titanium precipitation treatment is 2.8 to 3.0. This facilitates the complete hydrolysis and precipitation of Ti in the reduced solution.
[0046] S6: Ammonia water is subjected to aluminum precipitation treatment with the titanium precipitation liquid to obtain aluminum precipitation liquid and aluminum hydroxide slag. The liquid after titanium precipitation is mixed with ammonia. The aluminum ions in the liquid react with the ammonia to produce aluminum hydroxide slag and the liquid after aluminum precipitation. The reaction formula is Al 3+ +3NH3·H2O=Al(OH)3↓+3NH4 + , In some embodiments, at least one of the following conditions is met: the final pH value of the aluminum precipitation treatment is 4.5~5.5; the temperature of the aluminum precipitation treatment is 70℃~85℃. This facilitates the complete reaction of aluminum ions in the solution with ammonia, leading to hydrolysis and precipitation.
[0047] S7: Oxygen is introduced into the aluminum-precipitated liquid to perform iron precipitation treatment, resulting in hematite slag and iron-precipitated liquid. The aluminum-precipitated liquid is mixed with oxygen to react and generate hematite slag, thus performing iron precipitation treatment. The reaction process includes: 4FeSO4 + O2 + 4H2O = 2FeO3 + 4H2SO4.
[0048] In some embodiments, the aluminum-precipitated liquid is mixed with oxygen in an autoclave to perform iron precipitation treatment.
[0049] In some embodiments, at least one of the following conditions is met: the temperature of the iron precipitation treatment is 165°C to 175°C; the final acidity of the iron precipitation treatment is 25 g / L to 30 g / L. This facilitates complete precipitation of Fe in the solution from the hematite slag.
[0050] In some embodiments, ammonium carbonate is mixed with the post-aluminum precipitation liquid to obtain the ferrous carbonate and ammonium sulfate solution. The mixing temperature is 15°C to 25°C, and the excess ammonium carbonate coefficient is 1.2 to 1.5. The reaction process of mixing the post-aluminum precipitation liquid and ammonium carbonate to generate the ferrous carbonate and ammonium sulfate solution includes: (NH4)2CO3 + FeSO4 = FeCO3↓ + (NH4)2SO4. This allows for the recycling of ferrous sulfate added during red mud treatment, resulting in the preparation of high-purity ferrous carbonate and the production of ammonium sulfate with application value.
[0051] In some embodiments, the method further includes: subjecting the ammonium sulfate solution to a second crystallization treatment to obtain ammonium sulfate and a second mother liquor, wherein the evaporation temperature of the second crystallization treatment is 80°C~110°C, and the crystallization temperature of the second crystallization treatment is 15°C~25°C; and mixing the second mother liquor with the aluminum precipitation liquid for the mixing treatment. Performing the second crystallization treatment under the aforementioned conditions allows the ammonium sulfate solution to continuously evaporate the solvent until it reaches a supersaturated state, thereby causing the ammonium sulfate to precipitate in crystal form, which is beneficial for obtaining high-purity ammonium sulfate and recovering the second mother liquor. The second mother liquor can be mixed and circulated with the aluminum precipitation liquid for further mixing treatment. This facilitates the preparation of high-purity ammonium sulfate.
[0052] In some embodiments, the second crystallization process is performed using mechanical vapor recompression (MVR) technology.
[0053] In some embodiments, the exhaust steam generated during the iron deposition process is used for the second crystallization treatment.
[0054] The following specific embodiments illustrate the solution of this application. It should be noted that these embodiments are for illustrative purposes only and should not be considered as limiting the scope of this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.
[0055] Example 1 Raw materials: Red mud contains elements such as aluminum, iron, titanium, sodium, and calcium, with Al₂O₃: 15.30%, Fe₂O₃: 24.50%, TiO₂: 6.86%, CaO: 17.50%, and Na₂O: 5.6%. S1: Red mud and water are added to the reaction tank at a liquid-solid ratio of 2:1 for sodium removal treatment, resulting in sodium removal residue and sodium sulfate washing solution. The reaction temperature is controlled at 90℃, the reaction time is 2h, and the final pH value is 5.0.
[0056] The main components and contents of the sodium sulfate washing solution are as follows: pH value 5.1, Na: 13.32 g / L, Fe: 0.084 g / L, Al: 0.013 g / L, Ti: 0.000295 g / L. The main components and contents of the sodium removal residue are as follows: Al: 8.09%, Fe: 17.12%, Ti: 4.1%, Ca: 12.48%, Na: 0.12%.
[0057] First crystallization treatment of sodium sulfate washing solution: The sodium sulfate washing solution is evaporated and crystallized to obtain anhydrous sodium sulfate and the first mother liquor. The evaporation temperature is controlled at 105℃ and the evaporation time is 3h. The cooling temperature is 20℃ and the cooling time is 4h. The drying temperature is 120℃ and the drying time is 10min.
[0058] The main components and content of the first mother liquor were Na: 124.2 g / L, and the main components and content of anhydrous sodium sulfate were Na2SO4: 98.15%. S2: Add the sodium removal residue and the second-stage leachate to the first-stage leaching tank at a liquid-solid ratio of 6:1 for first-stage leaching treatment to obtain first-stage leachate and first-stage leaching residue. Control the reaction temperature at 80℃, the reaction time at 2h, and the final acidity at 10g / L.
[0059] The main components and contents of the first-stage leachate are H2SO4: 11.2 g / L, Al: 14.8 g / L, Ti: 4.9 g / L, and Fe: 6.6 g / L, while the main components and contents of the first-stage leachate residue are Al: 1.13%, Fe: 9.04%, Ti: 1.12%, Ca: 16.32%, and Na: 0.19%.
[0060] S3: Add the first-stage leaching residue and dilute acid to the second-stage leaching tank at a liquid-solid ratio of 8:1 for second-stage leaching treatment to obtain second-stage leaching solution and second-stage leaching residue. Control the reaction temperature at 80℃, the reaction time at 3h, and the final acidity at 140g / L.
[0061] The main components and contents of the second-stage leachate are H2SO4: 142.3 g / L, Al: 2.8 g / L, Ti: 1.24 g / L, and Fe: 2.23 g / L, while the main components and contents of the second-stage leachate residue are Al: 0.31%, Fe: 8.81%, Ti: 0.38%, Ca: 10.75%, and Na: 0.14%.
[0062] S4: Add a section of leachate to the reaction tank, introduce sulfur dioxide for reduction treatment, and obtain the reduced liquid. Control the excess sulfur dioxide coefficient to be 1.4, the reaction temperature to be 70℃, and the reaction time to be 30min.
[0063] The main components and contents of the reduced solution are H2SO4: 13.2 g / L, Al: 14.5 g / L, Ti: 4.8 g / L, and Fe: 6.5 g / L.
[0064] S5: The reduced liquid is added to the reaction tank and heated. Ferrous carbonate is added for titanium precipitation treatment to obtain titanium-precipitated liquid and titanium slag. The temperature is 100℃, the reaction time is 30min, the final pH value is 3.0, and the excess coefficient of ferrous carbonate is 1.2.
[0065] The main components and contents of the titanium precipitation solution are H2SO4: 12.9 g / L, Al: 13.8 g / L, Ti: 0.04 g / L, and Fe: 6.4 g / L, while the main components and contents of the titanium slag are Al: 1.3% and Ti: 11.8%.
[0066] S6: Add the titanium precipitation liquid to the aluminum precipitation tank, slowly add ammonia water to carry out aluminum precipitation treatment, and obtain aluminum precipitation liquid and aluminum hydroxide slag. Control the reaction temperature at 70℃, the reaction time at 60min, and the final pH value at 5.5.
[0067] The main components and contents of the aluminum precipitation liquid are as follows: pH value 4.9, Al: 0.035 g / L, Fe: 6.2 g / L, Ti: 0.00014 g / L, and the main components and contents of the aluminum hydroxide slag are as follows: Al2O3: 42.61%, Ti: 0.095%, Fe: 0.43%.
[0068] S7: Add the aluminum-precipitated liquid to the pressure vessel, introduce oxygen to perform iron precipitation treatment, and obtain hematite slag and iron-precipitated liquid. Control the reaction temperature at 165℃ and the reaction time at 2h.
[0069] The main components and contents of the liquid after iron precipitation are H2SO4: 25.12g / L and Fe: 0.31g / L, while the main components and contents of the hematite slag are Fe: 64.28% and Ti: 0.013%.
[0070] The aluminum-precipitated liquid was added to the reaction tank, and ammonium carbonate was added for mixing to obtain the ferrous carbonate and ammonium sulfate solution. The reaction temperature was controlled at 15°C, the reaction time at 30 min, the aging time at 60 min, and the excess amount of ammonium carbonate was 1.5 times.
[0071] The main components and contents of the ammonium sulfate solution are: pH value 6.9, NH4+. + :11.2g / L, Fe:0.3g / L, of which the main component and content of ferrous carbonate is FeCO3:98.2%.
[0072] The ammonium sulfate solution underwent a second crystallization treatment: the exhaust steam generated during the iron precipitation process was used to evaporate and crystallize the aluminum-precipitated liquid, yielding ammonium sulfate and a second mother liquor. The reaction temperature was controlled at 110℃ for 6 hours, the crystallization aging temperature was 25℃ for 2 hours, the drying temperature was 80℃, and the drying time was 15 minutes.
[0073] The main components and contents of the second mother liquor are: pH value 5.5, NH4+. + 214.2 g / L, of which ammonium sulfate content is 99.1%. Example 2 Raw materials: Red mud contains elements such as aluminum, iron, titanium, sodium, and calcium, with the following percentages: Al₂O₃: 15.30%, Fe₂O₃: 22.50%, TiO₂: 6.86%, CaO₂: 4.50%, and Na₂O: 5.6%. S1: Red mud and water are added to the reaction tank at a liquid-solid ratio of 2.5:1 for sodium removal treatment, resulting in sodium removal residue and sodium sulfate washing solution. The reaction temperature is controlled at 85℃, the reaction time is 1.5h, and the final pH value is 4.9.
[0074] The main components and contents of the sodium sulfate washing solution are as follows: pH value 4.9, Na: 12.42 g / L, Fe: 0.075 g / L, Al: 0.011 g / L, Ti: 0.0002 g / L. The main components and contents of the sodium removal residue are as follows: Al: 8.13%, Fe: 17.22%, Ti: 4.3%, Ca: 13.21%, Na: 0.13%.
[0075] First crystallization treatment of sodium sulfate washing solution: The sodium sulfate washing solution was evaporated and crystallized to obtain anhydrous sodium sulfate and the first mother liquor. The evaporation temperature was controlled at 107℃ and the evaporation time was 2.5h. The cooling temperature was controlled at 25℃ and the cooling time was 3h. The drying temperature was controlled at 135℃ and the drying time was 15min.
[0076] The main components and content of the first mother liquor are Na: 120.5 g / L, and the main components and content of anhydrous sodium sulfate are Na2SO4: 98.22%. S2: Add the sodium removal residue and the second-stage leachate to the first-stage leaching tank at a liquid-solid ratio of 5:1 for first-stage leaching treatment to obtain first-stage leachate and first-stage leaching residue. Control the reaction temperature at 85℃, the reaction time at 2.5h, and the final acidity at 15g / L.
[0077] The main components and contents of the leachate from one stage were: H₂SO₄: 14.3 g / L, Al: 15.2 g / L, Ti: 4.6 g / L, Fe: 7.2 g / L; and the main components and contents of the leaching residue from the first stage were: Al: 1.08%, Fe: 9.24%, Ti: 1.1%, Ca: 16.31%, Na: 0.15%. S3: Add the first-stage leaching residue and dilute acid to the second-stage leaching tank at a liquid-solid ratio of 7:1 for second-stage leaching treatment to obtain second-stage leaching solution and second-stage leaching residue. Control the reaction temperature at 85℃, the reaction time at 2.5h, and the final acidity at 145g / L.
[0078] The main components and contents of the second-stage leachate were: H₂SO₄: 145.6 g / L, Al: 2.5 g / L, Ti: 1.5 g / L, Fe: 2.4 g / L; and the main components and contents of the second-stage leachate residue were: Al: 0.39%, Fe: 8.42%, Ti: 0.31%, Ca: 11.25%, Na: 0.13%. S4: Add a section of leachate to the reaction tank, introduce sulfur dioxide for reduction treatment, and obtain the reduced liquid. Control the excess sulfur dioxide coefficient to be 1.3, the reaction temperature to be 80℃, and the reaction time to be 45min.
[0079] The main components and contents of the reduced solution are H2SO4: 16.5 g / L, Al: 14.9 g / L, Ti: 4.4 g / L, and Fe: 6.9 g / L.
[0080] S5: The reduced liquid is added to the reaction tank and heated. Ferrous carbonate is added for titanium precipitation treatment to obtain titanium-precipitated liquid and titanium slag. The temperature is 95℃, the reaction time is 45min, the final pH value is 2.9, and the excess coefficient of ferrous carbonate is 1.4.
[0081] The main components and contents of the titanium precipitation solution are H2SO4: 17.1 g / L, Al: 14.2 g / L, Ti: 0.05 g / L, and Fe: 6.7 g / L, while the main components and contents of the titanium slag are Al: 1.1% and Ti: 8.2%.
[0082] S6: Add the titanium precipitation liquid to the aluminum precipitation tank, slowly add ammonia water to carry out aluminum precipitation treatment, and obtain aluminum precipitation liquid and aluminum hydroxide slag. Control the reaction temperature at 80℃, the reaction time at 45min, and the final pH value at 5.0.
[0083] The main components and contents of the aluminum precipitation liquid are as follows: pH value 4.9, Al: 0.035 g / L, Fe: 7.41 g / L, Ti: 0.00019 g / L, and the main components and contents of the aluminum hydroxide slag are as follows: Al2O3: 43.46%, TiO2: 0.079%, Fe: 0.51%.
[0084] S7: Add the aluminum-precipitated liquid to the pressure vessel, introduce oxygen to perform iron precipitation treatment, and obtain hematite slag and iron-precipitated liquid. Control the reaction temperature at 170℃ and the reaction time at 1.5h.
[0085] The main components and contents of the liquid after iron precipitation are H2SO4: 28.92g / L and Fe: 0.42g / L, while the main components and contents of the hematite slag are Fe: 65.21% and Ti: 0.012%.
[0086] After adding aluminum, the liquid is added to the reaction tank, and ammonium carbonate is added for mixing to obtain the ferrous carbonate and ammonium sulfate solution. The reaction temperature is controlled at 20°C, the reaction time at 20 min, the aging time at 45 min, and the excess amount of ammonium carbonate is 1.3 times.
[0087] The main components and contents of the ammonium sulfate solution are: pH value 7.2, NH4+. + 11.11 g / L, SO4 2- The concentration of ferrous carbonate is 40.12 g / L, and the concentration of Fe is 0.5 g / L. The main component and content of ferrous carbonate is FeCO3: 98.4%. The ammonium sulfate solution underwent a second crystallization treatment: the exhaust steam generated during the iron precipitation process was used to evaporate and crystallize the aluminum-precipitated liquid, yielding ammonium sulfate and a second mother liquor. The reaction temperature was controlled at 100℃ for 7 hours, the crystallization aging temperature was 20℃ for 1 hour, and the drying temperature was 90℃ for 20 minutes.
[0088] The main components and contents of the second mother liquor are: pH value 5.2, NH4+. + 220.2 g / L, of which ammonium sulfate content is 98.9%.
[0089] Example 3 Raw materials: Red mud contains elements such as aluminum, iron, titanium, sodium, and calcium, with the following percentages: Al₂O₃: 15.30%, Fe₂O₃: 22.50%, TiO₂: 6.86%, CaO₂: 4.50%, and Na₂O: 5.6%. S1: Red mud and water are added to the reaction tank at a liquid-solid ratio of 3:1 for sodium removal treatment, resulting in sodium removal residue and sodium sulfate washing solution. The reaction temperature is controlled at 80℃, the reaction time is 1 hour, and the final pH value is 4.8.
[0090] The main components and contents of the sodium sulfate washing solution are as follows: pH value 5.1, Na: 13.32 g / L, Fe: 0.075 g / L, Al: 0.012 g / L, Ti: 0.0001 g / L. The main components and contents of the sodium removal residue are as follows: Al: 7.88%, Fe: 16.35%, Ti: 4.3%, Ca: 12.28%, Na: 0.1%.
[0091] First crystallization treatment of sodium sulfate washing solution: The sodium sulfate washing solution is evaporated and crystallized to obtain anhydrous sodium sulfate and the first mother liquor. The evaporation temperature is controlled at 110℃ and the evaporation time is 2h. The cooling temperature is controlled at 30℃ and the cooling time is 2h. The drying temperature is controlled at 150℃ and the drying time is 20min.
[0092] The main components and content of the first mother liquor were Na: 130.1 g / L, and the main components and content of anhydrous sodium sulfate were Na2SO4: 98.27%. S2: Add the sodium removal residue and the second-stage leachate to the first-stage leaching tank at a liquid-solid ratio of 4:1 for first-stage leaching treatment to obtain first-stage leachate and first-stage leaching residue. Control the reaction temperature at 90℃, the reaction time at 3h, and the final acidity at 20g / L.
[0093] The main components and contents of the first-stage leachate are H2SO4: 21.8 g / L, Al: 15.9 g / L, Ti: 5.1 g / L, and Fe: 8.2 g / L, while the main components and contents of the first-stage leachate residue are Al: 1.52%, Fe: 9.5%, Ti: 1.35%, Ca: 15.93%, and Na: 0.1%.
[0094] S3: Add the first-stage leaching residue and dilute acid to the second-stage leaching tank at a liquid-solid ratio of 6:1 for second-stage leaching treatment to obtain second-stage leaching solution and second-stage leaching residue. Control the reaction temperature at 90℃, the reaction time at 2h, and the final acidity at 150g / L.
[0095] The main components and contents of the second-stage leachate were H2SO4: 151.3 g / L, Al: 2.8 g / L, Ti: 1.2 g / L, and Fe: 3.48 g / L, while the main components and contents of the second-stage leachate residue were Al: 0.41%, Fe: 8.29%, Ti: 0.35%, Ca: 10.28%, and Na: 0.1%.
[0096] S4: Add a section of leachate to the reaction tank, introduce sulfur dioxide for reduction treatment, and obtain the reduced liquid. Control the excess sulfur dioxide coefficient to be 1.2, the reaction temperature to be 85℃, and the reaction time to be 60min.
[0097] The main components and contents of the reduced solution are H2SO4: 21.8 g / L, Al: 15.5 g / L, Ti: 4.8 g / L, and Fe: 7.5 g / L.
[0098] S5: The reduced liquid is added to the reaction tank and heated. Ferrous carbonate is added for titanium precipitation treatment to obtain titanium-precipitated liquid and titanium slag. The temperature is 90℃, the reaction time is 60min, the final pH value is 2.8, and the excess coefficient of ferrous carbonate is 1.5.
[0099] The main components and contents of the titanium precipitation solution are H2SO4: 25.9 g / L, Al: 15.2 g / L, Ti: 0.09 g / L, and Fe: 7.4 g / L, while the main components and contents of the titanium slag are Al: 1.3% and Ti: 8.1%.
[0100] S6: Add the titanium precipitation liquid to the aluminum precipitation tank, slowly add ammonia water to carry out aluminum precipitation treatment, and obtain aluminum precipitation liquid and aluminum hydroxide slag. Control the reaction temperature at 85℃, the reaction time at 30min, and the final pH value at 4.5.
[0101] The main components and contents of the aluminum precipitation liquid are as follows: pH value 4.7, Al: 0.058 g / L, Fe: 7.1 g / L, Ti: 0.00051 g / L, and the main components and contents of the aluminum hydroxide slag are as follows: Al2O3: 49.31%, TiO2: 0.032%, Fe: 0.57%.
[0102] S7: Add the aluminum-precipitated liquid to the pressure vessel, introduce oxygen to perform iron precipitation treatment, and obtain hematite slag and iron-precipitated liquid. Control the reaction temperature at 175℃ and the reaction time at 1h.
[0103] The main components and contents of the liquid after iron precipitation are H2SO4: 26.83g / L and Fe: 0.28g / L, while the main components and contents of the hematite slag are Fe: 65.29% and Ti: 0.029%.
[0104] After adding aluminum, the liquid is added to the reaction tank, and ammonium carbonate is added for mixing to obtain the ferrous carbonate and ammonium sulfate solution. The reaction temperature is controlled at 25°C, the reaction time is 15 min, the aging time is 30 min, and the excess amount of ammonium carbonate is 1.2 times.
[0105] The main components and contents of the ammonium sulfate solution are: pH value 6.9, NH4+. + 12.7 g / L, SO4 2- 41.38 g / L, Fe: 0.5 g / L, of which the main component and content of ferrous carbonate is FeCO3: 98.4%.
[0106] The ammonium sulfate solution underwent a second crystallization treatment: the exhaust steam generated during the iron precipitation process was used to evaporate and crystallize the aluminum-precipitated liquid, yielding ammonium sulfate and a second mother liquor. The reaction temperature was controlled at 95℃ for 8 hours, the crystallization aging temperature at 20℃ for 1 hour, and the drying temperature at 100℃ for 15 minutes.
[0107] The main components and contents of the second mother liquor are: pH value 6.3, NH4+. + 210.2 g / L, of which ammonium sulfate content is 99.3%. In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. "First feature" and "second feature" may include one or more of the indicated feature.
[0108] In the description of this application, "A and / or B" can include any of the cases of A alone, B alone, or A and B, where A and B are merely examples and can be any technical feature connected by "and / or" in this application.
[0109] In this application, the order in which the steps are written does not imply a strict execution order and does not limit the implementation process. The specific execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps in this application can be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.
[0110] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.
Claims
1. A method for treating red mud, characterized in that, include: Red mud was treated with sulfuric acid solution to remove sodium, resulting in sodium sulfate washing solution and sodium removal residue; The sodium-removed residue is subjected to a first-stage leaching treatment to obtain a first-stage leachate and a first-stage leaching residue; The first-stage leaching residue is subjected to a second-stage leaching treatment to obtain a second-stage leachate and a second-stage leaching residue, wherein the second-stage leaching residue includes iron-calcium slag. Sulfur dioxide was introduced into the leachate to reduce it, resulting in a reduced solution. The reduced liquid was subjected to titanium precipitation treatment with ferrous carbonate to obtain a titanium-precipitated liquid and titanium slag. Ammonia water is mixed with the titanium precipitation liquid to perform aluminum precipitation treatment, resulting in aluminum precipitation liquid and aluminum hydroxide slag. Oxygen is introduced into the aluminum-precipitated liquid to perform iron precipitation treatment, resulting in hematite slag and iron-precipitated liquid.
2. The method according to claim 1, characterized in that, At least one of the following conditions must be met: The final pH value of the sodium removal treatment is 4.8~5.0; The temperature for the sodium removal process is 80℃~90℃; The liquid-to-solid ratio of the sodium removal treatment is 2L / kg to 3L / kg.
3. The method according to claim 1, characterized in that, At least one of the following conditions must be met: The final acidity of the leaching treatment is 10 g / L to 20 g / L; The temperature of the leaching process is 80℃~90℃; The liquid-to-solid ratio of the leaching process is 4L / kg to 6L / kg. The final acidity of the two-stage leaching treatment is 140 g / L to 150 g / L; The liquid-to-solid ratio of the two-stage leaching treatment is 8L / kg to 8L / kg. The temperature for the two-stage leaching process is 80℃~90℃.
4. The method according to claim 1, characterized in that, At least one of the following conditions must be met: The reduction treatment temperature is 70℃~85℃; The reduction process takes 30 to 60 minutes. The excess sulfur dioxide coefficient of the reduction treatment is 1.2~1.
4.
5. The method according to claim 1, characterized in that, At least one of the following conditions must be met: The temperature for the titanium deposition treatment is 90℃~100℃; The final pH value of the titanium precipitation treatment reaction is 2.8~3.0; The final pH value of the aluminum deposition treatment is 4.5~5.5; The temperature for the aluminum plating process is 70℃~85℃; The temperature for the iron immersion treatment is 165℃~175℃; The final acidity of the iron deposition treatment is 25 g / L to 30 g / L.
6. The method according to any one of claims 1 to 5, characterized in that, Also includes: The second-stage leachate and the sodium-removed residue are subjected to the first-stage leaching treatment.
7. The method according to any one of claims 1 to 5, characterized in that, Also includes: The sodium sulfate washing solution is subjected to a first crystallization treatment to obtain sodium sulfate and a first mother liquor, wherein the evaporation temperature of the first crystallization treatment is 105℃~110℃ and the crystallization temperature of the first crystallization treatment is 20℃~30℃. The first mother liquor is mixed with the sulfuric acid solution to perform the sodium removal treatment.
8. The method according to any one of claims 1 to 5, characterized in that, Also includes: Ammonium carbonate is mixed with the aluminum precipitation solution to obtain the ferrous carbonate and ammonium sulfate solution. The mixing temperature is 15℃~25℃ and the excess coefficient of ammonium carbonate in the mixing process is 1.2~1.
5.
9. The method according to claim 8, characterized in that, Also includes: The ammonium sulfate solution is subjected to a second crystallization treatment to obtain ammonium sulfate and a second mother liquor. The evaporation temperature of the second crystallization treatment is 80℃~110℃, and the crystallization temperature of the second crystallization treatment is 15℃~25℃. The second mother liquor is mixed with the aluminum precipitation liquid for the mixing treatment.
10. The method according to any one of claims 1 to 5, characterized in that, Also includes: The second-stage leaching residue is washed to obtain the iron-calcium slag, wherein the liquid-to-solid ratio of the washing process is 3L / kg to 4L / kg, and the washing process temperature is 40℃ to 60℃.