Resource utilization method of Bayer process red mud
Through the treatment of dilute hydrochloric acid and alkaline additives, the problem of low resource utilization rate of Bayer method is solved, and the resource recycling of aluminum, iron and sodium in red mud and the environmentally friendly utilization of red mud is realized, reducing production costs .
Patent Information
- Application Number
- CN202411267737.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-11
- Publication Date
- 2024-12-13
AI Technical Summary
The existing technology fails to effectively utilize Bayer method red mud, resulting in waste of resources and environmental pollution.
By adding dilute hydrochloric acid to the Bayer method red mud slurry, performing a selective leaching reaction, sodium chloride, aluminum chloride and iron chloride were separated, and the filtrate was purified by alkaline additives, and the silica-free ore and sodium hydroxide were recovered. , realize the resource utilization of aluminum, iron and sodium in red mud.
It improves the resource utilization rate of red mud, saves the amount of hydrochloric acid, reduces production costs, and converts red mud into high-grade aluminum ore and building materials, realizing resource recycling of sodium oxide, alumina and iron oxide.
Smart Images
Figure CN119120932A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of Bayer process red mud, and in particular to a method for resource utilization of Bayer process red mud. Background Art
[0002] Red mud is a waste product produced in the process of refining alumina from bauxite. It is named for its reddish mud. With the continuous development of the bauxite industry, my country's red mud emissions are more than 15 million tons per year. With the commissioning of new equipment and the increase in production and transformation of old equipment, the total mass of red mud has an upward trend and has caused certain harm to the environment. Red mud is the largest waste generated in the production process of alumina and the largest source of pollution in alumina production. Due to different production methods and bauxite grades, each ton of alumina produces approximately 0.5-2.5 tons of red mud, and each ton of red mud is accompanied by 3-4m 3 Alkaline waste liquid.
[0003] Red mud production methods include the Bayer process, which uses strong alkali NaOH to dissolve high-aluminum and high-iron bauxite, and produces red mud with high content of aluminum oxide, iron oxide and alkali; it processes boehmite and gibbsite bauxite. In terms of resource utilization of red mud from the Bayer process, effective resource utilization of red mud has not been achieved so far. Summary of the invention
[0004] The present application provides a method for resource utilization of Bayer process red mud to solve the following technical problem: how to improve the resource utilization rate of Bayer process red mud.
[0005] In a first aspect, the present application provides a method for resource utilization of Bayer process red mud, the method comprising:
[0006] adding dilute hydrochloric acid to the first Bayer process red mud slurry to obtain a second Bayer process red mud slurry having a set molar ratio of chloride ions to sodium ions;
[0007] subjecting the second Bayer process red mud slurry to a leaching reaction, and then subjecting the reaction product of the leaching reaction to a first filtration to obtain a filtrate and a first dealkalized red mud filter cake;
[0008] adding an alkaline auxiliary agent to the filtrate to purify the filtrate to obtain a purified filtrate for recycling;
[0009] Washing the first dealkalized red mud filter cake to obtain a chloride ion-containing washing liquid and a second dealkalized red mud filter cake;
[0010] The second dealkalized red mud filter cake is recycled, and the chloride ion-containing washing liquid is returned to participate in the preparation of the dilute hydrochloric acid for recycling.
[0011] Optionally, the weight concentration of the dilute hydrochloric acid is 1% to 5%.
[0012] Optionally, the molar ratio of chloride ions to sodium ions is set to 0.9 to 1.6.
[0013] Optionally, the molar ratio of chloride ions to sodium ions is set to 1 to 1.4.
[0014] Optionally, the process parameters of the leaching reaction include: a reaction temperature of 5°C to 150°C, and a reaction time of 0.05h to 1h.
[0015] Optionally, the process parameters of the leaching reaction include: a reaction temperature of 20°C to 60°C, and a reaction time of 0.1h to 0.3h.
[0016] Optionally, the weight fraction of the Bayer process red mud in the first Bayer process red mud slurry is 10% to 60%.
[0017] Optionally, the alkaline auxiliary agent includes at least one of the following: sodium hydroxide solution, sodium carbonate solution, and the concentration of the alkaline auxiliary agent is 1 g / L to 200 g / L.
[0018] Optionally, the endpoint pH of the purification satisfies: 5 <pH<7。
[0019] Optionally, the method further includes:
[0020] The purified filtrate is subjected to a second filtration to obtain a silicon-aluminum ore filter cake and a sodium chloride filtrate;
[0021] The sodium chloride filtrate is electrolyzed to obtain sodium hydroxide.
[0022] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:
[0023] The method for resource utilization of Bayer process red mud provided in an embodiment of the present application comprises: adding dilute hydrochloric acid to a first Bayer process red mud slurry to obtain a second Bayer process red mud slurry having a set molar ratio of chloride ions to sodium ions; subjecting the second Bayer process red mud slurry to a leaching reaction, and then subjecting the reaction product of the leaching reaction to a first filtration to obtain a filtrate and a first dealkalized red mud filter cake; adding an alkaline auxiliary agent to the filtrate to purify the filtrate to obtain a purified filtrate for recycling; washing the first dealkalized red mud filter cake to obtain a chloride ion washing liquid and a second dealkalized red mud filter cake; recycling the second dealkalized red mud filter cake, and returning the chloride ion washing liquid to participate in the preparation of the dilute hydrochloric acid for recycling. In a second Bayer process red mud slurry with a set molar ratio of chloride to sodium ions, dilute hydrochloric acid selectively leaches the Bayer process red mud to separate sodium chloride, aluminum chloride and ferric chloride; the first dealkalized red mud filter cake obtained by the first filtration is washed to remove part of the chloride ions, so as to obtain a second dealkalized red mud filter cake as a raw material for building materials; the chloride ion-containing washing liquid can be returned to participate in the configuration of the above-mentioned dilute hydrochloric acid to provide chloride ions for the second Bayer process red mud slurry system, thereby saving the amount of hydrochloric acid; the filtrate containing sodium chloride, aluminum chloride and ferric chloride reacts with an alkaline auxiliary agent to purify the filtrate, so that the filtrate can be converted into a purified filtrate containing aluminum-iron precipitate (silicon-free aluminum ore); the silicon-free aluminum ore can be used as a high-grade aluminum ore; the solution part of the purified filtrate is a sodium chloride solution, and the sodium chloride solution can be electrolyzed to obtain sodium hydroxide, thereby realizing the resource utilization of aluminum, iron and sodium in the Bayer process red mud. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.
[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.
[0026] Figure 1 A schematic flow chart of a method for resource utilization of Bayer process red mud provided in an embodiment of the present application. DETAILED DESCRIPTION
[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.
[0028] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.
[0029] In the present application, in the absence of any contrary description, the directional words used, such as "upper" and "lower", are specifically the directions of the drawings in the accompanying drawings. In addition, in the description of the present specification, the terms "include", "comprise", etc. refer to "including but not limited to". In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, wherein a, b, c can be single or multiple, respectively.
[0030] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.
[0031] In the first aspect, the present application provides a method for resource utilization of Bayer process red mud. Figure 1 For a flow chart of a method for resource utilization of Bayer red mud provided in the embodiment of the present application, please refer to Figure 1 , the method comprising:
[0032] S1, adding dilute hydrochloric acid to the first Bayer process red mud slurry to obtain a second Bayer process red mud slurry having a set molar ratio of chloride ions to sodium ions;
[0033] In some embodiments, the weight concentration of the dilute hydrochloric acid is 1% to 5%.
[0034] In the embodiment of the present application, dilute hydrochloric acid is used to selectively leach sodium, aluminum and iron from Bayer red mud. The dilute hydrochloric acid can control the reaction depth of the leaching reaction and fully leach sodium, as well as an appropriate amount of aluminum and iron in the Bayer red mud. The weight concentration of the dilute hydrochloric acid can be 1% to 5%. If the weight concentration of the dilute hydrochloric acid is too high, it is difficult to control the reaction depth of the leaching reaction to a certain extent, which may lead to excessive leaching of aluminum and iron, as well as leaching of other excess elements such as silicon, so that SiO2 generates silica gel and increases the difficulty of subsequent filtration. Exemplarily, the weight concentration of the above-mentioned dilute hydrochloric acid can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc.
[0035] In some embodiments, the molar ratio of chloride ions to sodium ions is set to 0.9 to 1.6.
[0036] In some embodiments, the molar ratio of chloride ions to sodium ions is set to be 1 to 1.4.
[0037] In the embodiment of the present application, the above-mentioned set chloride-sodium ion molar ratio can be 0.9-1.6, which can provide a sufficient amount of dilute hydrochloric acid for the first Bayer process red mud slurry system, thereby ensuring the subsequent leaching effect of sodium, aluminum and iron, and thus improving the resource utilization rate of the Bayer process red mud; if the set chloride-sodium ion molar ratio is too high and greater than 1.6, it means that the chloride ions in the second Bayer process red mud slurry are excessive, which will affect the chloride ions in the subsequent washing liquid and the second dealkalization filter cake to a certain extent, which is not conducive to the subsequent application of the second dealkalization filter cake and increases the cost to a certain extent; if the set chloride-sodium ion molar ratio is too low and less than 0.9, it will cause incomplete leaching reaction to a certain extent, making it difficult to achieve the desired leaching effect, and the resource utilization rate of the Bayer process red mud will decrease. Exemplarily, the above-mentioned set molar ratio of chloride to sodium ions can be 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, etc.; further, the set molar ratio of chloride to sodium ions can be 1.0, 1.1, 1.2, 1.3, 1.4, etc.
[0038] In some embodiments, the weight fraction of the Bayer process red mud in the first Bayer process red mud slurry is 10% to 60%.
[0039] In the embodiment of the present application, the weight fraction of the Bayer process red mud in the first Bayer process red mud slurry can be 10% to 60%, which can ensure the smooth progress of the leaching reaction. Exemplarily, the weight fraction of the Bayer process red mud in the first Bayer process red mud slurry can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, etc.
[0040] S2, subjecting the second Bayer process red mud slurry to a leaching reaction, and then subjecting the reaction product of the leaching reaction to a first filtration to obtain a filtrate and a first dealkalized red mud filter cake;
[0041] In some embodiments, the process parameters of the leaching reaction include: a reaction temperature of 5°C to 150°C, and a reaction time of 0.05h to 1h.
[0042] In some embodiments, the process parameters of the leaching reaction include: a reaction temperature of 20° C. to 60° C., and a reaction time of 0.1 h to 0.3 h.
[0043] In an embodiment of the present application, dilute hydrochloric acid can provide hydrogen ions and chloride ions, and under the conditions of a reaction temperature of 5°C to 150°C and a reaction time of 0.05h to 1h, dilute hydrochloric acid selectively leaches sodium, aluminum and iron from Bayer red mud, and controls the depth of the leaching reaction, thereby fully leaching the sodium in the Bayer red mud, as well as an appropriate amount of aluminum and iron, to obtain a mixed slurry containing sodium chloride, aluminum chloride and ferric chloride; hydrogen ions react with hydroxide ions to generate water, thereby reducing the alkalinity of the Bayer red mud, and after the slurry after the leaching reaction is filtered for the first time, the filtrate is a mixed solution containing sodium chloride, aluminum chloride and ferric chloride. Exemplarily, the reaction temperature can be 5°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, etc., and the reaction time can be 0.05h, 0.1h, 0.2h, 0.3h, 0.4h, 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, etc.; further, the reaction temperature can be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, etc., and the time can be 0.1h, 0.2h, 0.3h, etc.
[0044] S3. Adding an alkaline auxiliary agent to the filtrate to purify the filtrate to obtain a purified filtrate for recycling.
[0045] In some embodiments, the alkaline auxiliary agent includes at least one of the following: sodium hydroxide solution, sodium carbonate solution, and the concentration of the alkaline auxiliary agent is 1 g / L to 200 g / L.
[0046] In the embodiments of the present application, the filtrate contains sodium chloride, aluminum chloride, and iron chloride. The filtrate undergoes a purification reaction with an alkaline auxiliary agent, which can transform the filtrate into a purified filtrate containing aluminum-iron precipitates (silica-free aluminum ore). The concentration of the alkaline auxiliary agent can be 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L, 110 g / L, 120 g / L, 130 g / L, 140 g / L, 150 g / L, 160 g / L, 170 g / L, 180 g / L, 190 g / L, 200 g / L, etc. Further, the concentration of the alkaline auxiliary agent can be 20 g / L, 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L, 110 g / L, 120 g / L, 130 g / L, 140 g / L, 150 g / L, 160 g / L, 170 g / L, 180 g / L, 190 g / L, 200 g / L, etc.
[0047] In some embodiments, the end-point pH of the purification satisfies: 5 < pH < 7.
[0048] In the embodiments of the present application, the end-point pH of the above purification can satisfy: 5 < pH < 7. The pH of the purified filtrate approaches neutrality, thus ensuring that a sufficient amount of the alkaline auxiliary agent fully reacts with aluminum chloride and iron chloride to form aluminum-iron precipitates, so that the solution part of the purified filtrate is a pure sodium chloride solution. Exemplarily, the end-point pH of the above purification can be 5.1, 5.3, 5.5, 5.8, 6, 6.3, 6.5, etc.
[0049] S4. Wash the first de-alkalized red mud filter cake to obtain a chloride-containing washing solution and a second de-alkalized red mud filter cake;
[0050] In the embodiments of the present application, the first de-alkalized red mud filter cake is washed to remove chloride ions, obtaining a chloride-containing washing solution and a second de-alkalized red mud filter cake. The washing medium can be water, and the addition amount of the washing water can be 0.5 to 5 times that of the first de-alkalized red mud filter cake. Further, the addition amount of the washing water can be 1 to 3 times that of the first de-alkalized red mud filter cake.
[0051] S5. Recycle the second de-alkalized red mud filter cake, and return the chloride-containing washing solution to participate in the preparation of the dilute hydrochloric acid for recycling.
[0052] In the embodiments of the present application, the second de-alkalized red mud filter cake obtained after washing can be used as a building material raw material, and the chloride-containing washing solution can be returned to participate in the preparation of the above dilute hydrochloric acid, which can provide chloride ions for the second Bayer process red mud slurry system, thereby saving the amount of hydrochloric acid used.
[0053] In some embodiments, the method further comprises:
[0054] S6, filtering the purified filtrate for the second time to obtain a silicon-aluminum ore filter cake and a sodium chloride filtrate;
[0055] S7. Electrolyze the sodium chloride filtrate to obtain sodium hydroxide.
[0056] In the embodiment of the present application, the silicon-free aluminum ore filter cake can be used as a high-grade aluminum ore; the solution part of the purified filtrate is a pure sodium chloride solution, and the pure sodium chloride solution can be electrolyzed to obtain sodium hydroxide, thereby realizing the resource utilization of aluminum, iron and sodium in the Bayer process red mud. In the embodiment of the present application, the resource utilization rate of sodium oxide in red mud is greater than 70%, the resource utilization rate of aluminum oxide is greater than 30%, and the resource utilization rate of iron oxide is greater than 40%.
[0057] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.
[0058] Example 1
[0059] A method for resource utilization of Bayer process red mud, comprising:
[0060] S11, adding dilute hydrochloric acid to the first Bayer process red mud slurry to obtain a second Bayer process red mud slurry with a set molar ratio of chloride to sodium ions; wherein, 100 grams of the first Bayer process red mud is taken, the weight fraction of the Bayer process red mud in the first Bayer process red mud slurry may be 40%, the concentration of hydrochloric acid is 1wt%, and the molar ratio of chloride to sodium ions [Cl] / [Na] is set to 0.9;
[0061] S21, subjecting the second Bayer process red mud slurry to a leaching reaction, and subjecting the reaction product of the leaching reaction to a first filtration to obtain a filtrate and a first dealkalized red mud filter cake; wherein the leaching reaction temperature is 30° C., and the reaction time is 0.1 h;
[0062] S31, adding an alkaline auxiliary agent to the filtrate to purify the filtrate to obtain a purified filtrate for recycling; wherein the alkaline auxiliary agent has a concentration of 20 g / L; the purification endpoint pH is 5.1, and the purification time is 0.2 h;
[0063] S41, washing the first dealkalized red mud filter cake to obtain a chloride ion washing solution and a second dealkalized red mud filter cake; wherein the amount of washing water added is 1 times the weight of the first dealkalized red mud filter cake; the second dealkalized red mud filter cake is 90 grams, and the sodium oxide content in the second dealkalized red mud filter cake is 0.7wt%;
[0064] S51, recycling the second dealkalized red mud filter cake, and returning the chloride ion-containing washing liquid to participate in the preparation of the dilute hydrochloric acid for recycling, and using the second dealkalized red mud filter cake as a raw material for building materials;
[0065] S61, filtering the purified filtrate for the second time to obtain a silicon-aluminum ore filter cake and a sodium chloride filtrate; wherein the silicon-aluminum ore filter cake is 5.4 grams;
[0066] S71. Electrolyze the sodium chloride filtrate to obtain sodium hydroxide.
[0067] Example 2
[0068] A method for resource utilization of Bayer process red mud, comprising:
[0069] S12, adding dilute hydrochloric acid to the first Bayer process red mud slurry to obtain a second Bayer process red mud slurry with a set molar ratio of chloride to sodium ions; wherein, 100 grams of the first Bayer process red mud is taken, the weight fraction of the Bayer process red mud in the first Bayer process red mud slurry may be 10%, the concentration of hydrochloric acid is 2wt%, and the molar ratio of chloride to sodium ions [Cl] / [Na] is set to be 1.4;
[0070] S22, subjecting the second Bayer process red mud slurry to a leaching reaction, and subjecting the reaction product of the leaching reaction to a first filtration to obtain a filtrate and a first dealkalized red mud filter cake; wherein the leaching reaction temperature is 60° C., and the reaction time is 0.3 h;
[0071] S32, adding an alkaline auxiliary agent to the filtrate to purify the filtrate to obtain a purified filtrate for recycling; wherein the alkaline auxiliary agent has a concentration of 80 g / L; the purification endpoint pH is 5.8, and the purification time is 1 h;
[0072] S42, washing the first dealkalized red mud filter cake to obtain a chloride ion washing solution and a second dealkalized red mud filter cake; wherein the amount of washing water added is 3 times the weight of the first dealkalized red mud filter cake; the second dealkalized red mud filter cake is 85.2 grams, and the sodium oxide content in the second dealkalized red mud filter cake is 0.3wt%;
[0073] S52, recycling the second dealkalized red mud filter cake, and returning the chloride ion-containing washing liquid to participate in the preparation of the dilute hydrochloric acid for recycling, and using the second dealkalized red mud filter cake as a raw material for building materials;
[0074] S62, filtering the purified filtrate for the second time to obtain a silicon-aluminum ore filter cake and a sodium chloride filtrate; wherein the silicon-aluminum ore filter cake is 8.1 grams;
[0075] S72, electrolyzing the sodium chloride filtrate to obtain sodium hydroxide.
[0076] Example 3
[0077] A method for resource utilization of Bayer process red mud, comprising:
[0078] S13, adding dilute hydrochloric acid to the first Bayer process red mud slurry to obtain a second Bayer process red mud slurry having a set molar ratio of chloride to sodium ions; wherein 100 g of the first Bayer process red mud is taken, the weight fraction of the Bayer process red mud in the first Bayer process red mud slurry may be 50%, the concentration of hydrochloric acid is 5 wt%, and the molar ratio of chloride to sodium ions [Cl] / [Na] is set to be 1.2;
[0079] S23, subjecting the second Bayer process red mud slurry to a leaching reaction, and subjecting the reaction product of the leaching reaction to a first filtration to obtain a filtrate and a first dealkalized red mud filter cake; wherein the leaching reaction temperature is 40° C., and the reaction time is 1 h;
[0080] S33, adding an alkaline auxiliary agent to the filtrate to purify the filtrate to obtain a purified filtrate for recycling; wherein the alkaline auxiliary agent has a concentration of 40 g / L; the purification endpoint pH is 6.3, and the purification time is 0.5 h;
[0081] S43, washing the first dealkalized red mud filter cake to obtain a chloride ion washing solution and a second dealkalized red mud filter cake; wherein the amount of washing water added is twice the weight of the first dealkalized red mud filter cake; the second dealkalized red mud filter cake is 89.3 grams, and the sodium oxide content in the second dealkalized red mud filter cake is 0.4wt%;
[0082] S53, recycling the second dealkalized red mud filter cake, and returning the chloride ion-containing washing liquid to participate in the preparation of the dilute hydrochloric acid for recycling, and using the second dealkalized red mud filter cake as a raw material for building materials;
[0083] S63, performing a second filtration on the purified filtrate to obtain a silicon-aluminum ore filter cake and a sodium chloride filtrate; wherein the silicon-aluminum ore filter cake is 6.8 grams;
[0084] S73, electrolyzing the sodium chloride filtrate to obtain sodium hydroxide.
[0085] Comparative Example 1
[0086] Based on the disclosure of Example 1, the difference between Comparative Example 1 and Example 1 is that the concentration of dilute hydrochloric acid is 7 wt %.
[0087] Comparative Example 2
[0088] Based on the disclosure of Example 1, Comparative Example 2 differs from Example 1 in that the molar ratio of chloride ions to sodium ions is set to 2.0.
[0089] The resource utilization rate of the Bayer process red mud provided by the methods for resource utilization of the Bayer process red mud provided in Examples 1 to 3 and Comparative Examples 1 to 2 was evaluated. Please see Table 1 for the results.
[0090] Table 1 Resource utilization rate of Bayer red mud
[0091] Serial number Sodium oxide resource utilization rate % Alumina resource utilization rate % Iron oxide resource utilization rate % Example 1 75 35 41 Example 2 82 55 58 Example 3 85 57 62 Comparative Example 1 - - - Comparative Example 2 - - -
[0092] As shown in Table 1, the method for resource utilization of the Bayer red mud provided in the present application realizes the resource utilization of aluminum, iron and sodium in the Bayer red mud. However, the concentration of dilute hydrochloric acid in Comparative Example 1 is high, resulting in a significant increase in the significant leaching rate of sodium, aluminum and iron in the leaching reaction, which means that the reaction depth is significantly enhanced, resulting in the formation of silica gel by SiO2 in the red mud. The presence of silica gel makes it difficult to separate the dissolved red mud residue from the solution, and it cannot be washed, and the process cannot operate normally; the molar ratio of chlorine and sodium ions is set to be high in Comparative Example 2, resulting in a significant increase in the significant leaching rate of sodium, aluminum and iron in the leaching reaction, and ultimately the resource utilization of aluminum, iron and sodium cannot be achieved.
[0093] One or more technical solutions in the embodiments of the present application also have at least the following technical effects or advantages:
[0094] (1) Using dilute hydrochloric acid to selectively leach sodium, aluminum and iron from Bayer red mud. Dilute hydrochloric acid can control the reaction depth of the leaching reaction and fully leach sodium, aluminum and iron in the Bayer red mud, thereby avoiding the formation of silica gel;
[0095] (2) The chloride ion-containing washing liquid can be returned to participate in the preparation of the above-mentioned dilute hydrochloric acid to provide chloride ions for the second Bayer process red mud slurry system, thereby saving the amount of hydrochloric acid;
[0096] (3) Recovering sodium oxide through electrolysis saves sodium costs in chlor-alkali plants and reduces production costs in alumina plants;
[0097] (4) The silicon-free aluminum ore filter cake is used as a silicon-free aluminum ore, and a portion of aluminum oxide and iron oxide in red mud are recovered at the same time;
[0098] (5) The sodium oxide content in the second dealkalized red mud filter cake is low and can be used on a large scale in industries such as cement and building materials.
[0099] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.
Claims
1. A method for resource utilization of Bayer red mud, characterized in that: The method comprises: adding dilute hydrochloric acid to the first Bayer process red mud slurry to obtain a second Bayer process red mud slurry having a set molar ratio of chloride ions to sodium ions; subjecting the second Bayer process red mud slurry to a leaching reaction, and then subjecting the reaction product of the leaching reaction to a first filtration to obtain a filtrate and a first dealkalized red mud filter cake; adding an alkaline auxiliary agent to the filtrate to purify the filtrate to obtain a purified filtrate for recycling; Washing the first dealkalized red mud filter cake to obtain a chloride ion-containing washing liquid and a second dealkalized red mud filter cake; The second dealkalized red mud filter cake is recycled, and the chloride ion-containing washing liquid is returned to participate in the preparation of the dilute hydrochloric acid for recycling.
2. The method according to claim 1, characterized in that The weight concentration of the dilute hydrochloric acid is 1% to 5%.
3. The method according to claim 1, characterized in that The molar ratio of chloride ions to sodium ions is set to 0.9 to 1.
6.
4. The method according to claim 3, characterized in that The molar ratio of chloride to sodium ions is set to be 1 to 1.
4.
5. The method according to claim 1, characterized in that The process parameters of the leaching reaction include: a reaction temperature of 5°C to 150°C and a reaction time of 0.05h to 1h.
6. The method according to claim 5, characterized in that The process parameters of the leaching reaction include: a reaction temperature of 20° C. to 60° C. and a reaction time of 0.1 h to 0.3 h.
7. The method according to claim 1, characterized in that The weight fraction of the Bayer process red mud in the first Bayer process red mud slurry is 10% to 60%.
8. The method according to claim 1, characterized in that The alkaline auxiliary agent includes at least one of the following: sodium hydroxide solution and sodium carbonate solution. The concentration of the alkaline auxiliary agent is 1 g / L to 200 g / L.
9. The method according to claim 1, characterized in that: The end point pH of the purification satisfies: 5 <pH<7。 10. The method according to claim 1, characterized in that The method further comprises: The purified filtrate is subjected to a second filtration to obtain a silicon-aluminum ore filter cake and a sodium chloride filtrate; The sodium chloride filtrate is electrolyzed to obtain sodium hydroxide.