Method for reducing hydrolysis loss of sodium aluminate solution

Abstract

The invention provides a method for reducing hydrolysis loss of a sodium aluminate solution, and belongs to the field of aluminum oxide production. The method comprises the following steps: mixing part of red mud washing water with dissolved-out ore pulp to carry out primary dilution, and carrying out heat preservation treatment to obtain diluted ore pulp; the diluted ore pulp is subjected to settling separation, and overflow liquid is obtained; mixing the overflow liquid with the rest red mud washing water for secondary dilution, and carrying out heat preservation treatment to obtain a sodium aluminate crude liquid; and carrying out solid-liquid separation on the sodium aluminate crude liquid to obtain a sodium aluminate fine liquid for seed crystal decomposition. The red mud washing water is diluted twice, the stability of the solution is not obviously reduced after the red mud washing water is diluted once, so that the hydrolysis loss in the dilution and separation processes is inhibited, the concentration of the solution is further reduced after the red mud washing water is diluted twice, and the decomposition rate of the sodium aluminate fine liquid in the subsequent decomposition process can be ensured. Therefore, the hydrolysis loss of the sodium aluminate solution is reduced and the seed crystal decomposition rate is improved in the production process of aluminum oxide by the overseas ore low-temperature Bayer process.

Description

Technical Field

[0001] The present application relates to the technical field of alumina production, and in particular to a method for reducing hydrolysis loss of sodium aluminate solution. Background Art

[0002] Due to the unique properties of overseas gibbsite ores, the slurry is less stable after low-temperature dissolution. This leads to significant hydrolysis losses during the dilution and separation process, increasing the alumina content in the red mud and reducing the net alumina dissolution rate of the ore. Hydrolysis of the slurry from domestic diaspore-type bauxite can reduce the net alumina dissolution rate by 1%, while hydrolysis of the slurry from overseas gibbsite-type bauxite can reduce the net alumina dissolution rate by 3%. This hydrolysis loss is three times that of domestic bauxite. Some Guinean bauxites with low silica content can even experience hydrolysis losses as high as 6%. For a low-temperature Bayer alumina refinery with an annual production capacity of 1 million tons, the economic losses from hydrolysis can reach tens of millions of yuan each year.

[0003] During alumina production, the highly concentrated and stable slurry obtained after high-pressure dissolution cannot be directly used for seed crystal decomposition and must be diluted with red mud wash water. High slurry dilution reduces solution stability, leading to aluminum hydroxide hydrolysis into the red mud during slurry dilution and separation, resulting in losses. Low slurry dilution significantly reduces hydrolysis losses, but also results in a lower subsequent seed crystal decomposition rate. Therefore, it is necessary to find a method that can suppress hydrolysis losses of the sodium aluminate solution while not adversely affecting the seed crystal decomposition rate. Summary of the Invention

[0004] The present application provides a method for reducing the hydrolysis loss of sodium aluminate solution to solve the following technical problem: how to reduce the hydrolysis loss of sodium aluminate solution and improve the seed crystal decomposition rate in the low-temperature Bayer process alumina production process of overseas mines.

[0005] The present invention provides a method for reducing hydrolysis loss of sodium aluminate solution, the method comprising:

[0006] Mixing a portion of the red mud wash water with the dissolved slurry for primary dilution, and performing a heat preservation treatment with a first set temperature and a first set time to obtain a diluted slurry;

[0007] subjecting the diluted slurry to sedimentation separation to obtain overflow liquid;

[0008] Mixing the overflow liquid with the remaining portion of red mud washing water for secondary dilution, and performing a heat preservation treatment with a second set temperature and a second set time to obtain a crude sodium aluminate solution; and

[0009] performing solid-liquid separation on the crude sodium aluminate liquid to obtain a sodium aluminate fine liquid for seed crystal decomposition;

[0010] The mass of the red mud washing water added in the first dilution accounts for 55% to 75% of the total mass of the red mud washing water, and the mass of the red mud washing water added in the second dilution accounts for 25% to 45% of the total mass of the red mud washing water.

[0011] Optionally, the mass of the red mud washing water added in the first dilution accounts for 65% to 70% of the total mass of the red mud washing water, and the mass of the red mud washing water added in the second dilution accounts for 30% to 35% of the total mass of the red mud washing water.

[0012] Optionally, the caustic soda concentration of the solution in the leaching slurry is 180 g / L to 210 g / L, and the molecular ratio of the solution in the leaching slurry is α k It is 1.33 to 1.45.

[0013] Optionally, the caustic soda concentration of the solution in the diluted slurry is 150 g / L to 180 g / L, and the molecular weight of the solution in the diluted slurry is α k It is 1.35 to 1.47.

[0014] Optionally, the caustic soda concentration of the sodium aluminate crude solution is 130 g / L to 160 g / L, and the molecular ratio of the solution in the sodium aluminate crude solution is α k It is 1.36~1.48.

[0015] Optionally, the molecular weight of the solution in the sodium aluminate semen is α k It is 1.36~1.48.

[0016] Optionally, the first set temperature is 103° C. to 108° C., and the first set time is 2 hours to 4 hours.

[0017] Optionally, the second set temperature is 100°C to 105°C, and the second set time is 1.5h to 2.5h.

[0018] Optionally, the suspended matter content of the sodium aluminate semen is <0.015g / L.

[0019] Optionally, in the process of producing alumina using the sodium aluminate concentrate, the molecular ratio difference Δα between the sodium aluminate concentrate and the solution in the dissolution slurry is k It is 0.01~0.04.

[0020] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0021] The present invention provides a method for reducing hydrolysis losses in sodium aluminate solution, comprising: mixing a portion of red mud wash water with a leached slurry for a primary dilution, and subjecting the mixture to a heat preservation treatment at a first set temperature and a first set time to obtain a diluted slurry; subjecting the diluted slurry to sedimentation separation to obtain an overflow liquid; mixing the overflow liquid with the remaining portion of red mud wash water for a secondary dilution, and subjecting the mixture to a heat preservation treatment at a second set temperature and a second set time to obtain a crude sodium aluminate solution; and subjecting the crude sodium aluminate solution to solid-liquid separation to obtain a refined sodium aluminate solution for seed crystal decomposition. Existing alumina production technology uses a sedimentation tank to mix red mud wash water with a leached slurry to obtain a diluted slurry with a low caustic concentration. The diluted slurry undergoes sedimentation separation and controlled filtration to obtain a refined sodium aluminate solution. The low-concentration sodium aluminate solution, in the dilution tank and the separation sedimentation tank, is induced by minerals such as goethite and boehmite in the red mud, causing aluminum hydroxide to crystallize and enter the red mud, resulting in hydrolysis losses. This application dilutes the red mud wash water twice. After the first dilution, the stability of the solution is not significantly reduced, thereby suppressing hydrolysis losses during the dilution and separation process. After the second dilution, the solution concentration is further reduced, which can ensure the decomposition rate of the sodium aluminate concentrate in the subsequent decomposition process. This reduces the hydrolysis loss of the sodium aluminate solution and improves the seed crystal decomposition rate during the low-temperature Bayer process alumina production process of overseas mines. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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.

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0024] Figure 1 A schematic flow chart of a method for reducing hydrolysis loss of sodium aluminate solution provided in an embodiment of the present application;

[0025] Figure 2 This is a schematic diagram of the actual process of a method for reducing hydrolysis loss of sodium aluminate solution provided in an embodiment of the present application. DETAILED DESCRIPTION

[0026] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0027] 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 hard 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 numbers within the range. For example, the description of a range 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 applies 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.

[0028] In addition, in the description of the specification of this application, the terms "including", "comprising", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" means one or more, and "plurality" means two or more. "At least one", "at least one of the following items (individuals)" or similar expressions refer to any combination of these items, including any combination of single items (individuals) or plural items (individuals). 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, where a, b, c can be single or multiple. "Parts" such as parts by weight and parts by mass represent the proportional relationship between the components. In the proportional relationship involved in this article, the parameters that need to be described by proportion should be understood as the first term of the proportional formula in the order of description, and the proportional numbers should be understood as the second term of the proportional formula. For example, if the mass ratio of substance A, substance B, and substance C is 1:2:3, then substance A, substance B, and substance C should correspond one-to-one to the proportional numbers in the proportional formula in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0029] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0030] Figure 1 A schematic flow chart of a method for reducing hydrolysis loss of sodium aluminate solution provided in an embodiment of the present application; Figure 2 This is a schematic diagram of the actual process of a method for reducing hydrolysis loss of sodium aluminate solution provided in an embodiment of the present application.

[0031] like Figure 1 and Figure 2 As shown, the present application provides a method for reducing hydrolysis loss of sodium aluminate solution, the method comprising:

[0032] S1, mixing a portion of the red mud wash water with the dissolved slurry for primary dilution, and performing a heat preservation treatment with a first set temperature and a first set time to obtain a diluted slurry;

[0033] S2, subjecting the diluted slurry to sedimentation separation to obtain overflow liquid;

[0034] S3, mixing the overflow liquid with the remaining portion of the red mud washing water for secondary dilution, and performing a heat preservation treatment with a second set temperature and a second set time to obtain a crude sodium aluminate solution; and

[0035] S4, performing solid-liquid separation on the crude sodium aluminate solution to obtain a sodium aluminate solution for seed crystal decomposition;

[0036] Existing alumina production technology uses red mud wash water from a settling tank to mix with dissolved slurry to obtain a diluted slurry with a low caustic soda concentration. The diluted slurry undergoes sedimentation separation and controlled filtration to obtain sodium aluminate concentrate. In the dilution tank and separation settling tank, the low-concentration sodium aluminate solution, induced by minerals such as aluminum goethite and boehmite in the red mud, causes aluminum hydroxide crystals to precipitate and enter the red mud, resulting in hydrolysis losses. The present application provides a method for reducing hydrolysis losses in the sodium aluminate solution by diluting the red mud wash water twice. After the first dilution, the stability of the solution is not significantly reduced, thereby suppressing hydrolysis losses during the dilution and separation processes. After the second dilution, the solution concentration is further reduced, which can ensure the decomposition rate of the sodium aluminate concentrate in the subsequent decomposition process.

[0037] In some embodiments, the mass of the red mud wash water added in the first dilution accounts for 55% to 75% of the total mass of the red mud wash water, and the mass of the red mud wash water added in the second dilution accounts for 25% to 45% of the total mass of the red mud wash water.

[0038] In some embodiments, the mass of the red mud wash water added in the first dilution accounts for 65% to 70% of the total mass of the red mud wash water, and the mass of the red mud wash water added in the second dilution accounts for 30% to 35% of the total mass of the red mud wash water.

[0039] In some embodiments, the caustic soda concentration of the solution in the dissolution slurry is 180 g / L to 210 g / L, and the molecular weight of the solution in the dissolution slurry is α k It is 1.33 to 1.45.

[0040] In some embodiments, the caustic soda concentration of the diluted slurry solution is 150 g / L to 180 g / L, and the molecular weight of the diluted slurry solution is α k It is 1.35 to 1.47.

[0041] In some embodiments, the caustic soda concentration of the sodium aluminate crude solution is 130 g / L to 160 g / L, and the molecular weight ratio of the solution in the sodium aluminate crude solution is α k It is 1.36~1.48.

[0042] In some embodiments, the molecular weight of the solution in the sodium aluminate semen is α k It is 1.36~1.48.

[0043] The reason for limiting the amount of wash water added in the first dilution and the caustic soda concentration of the solution in the diluted slurry is that the lower the caustic soda concentration of the sodium aluminate solution, the worse the stability. A higher concentration of sodium aluminate solution can effectively inhibit the precipitation of aluminum hydroxide and reduce hydrolysis losses in the dilution process and sedimentation separation process. The reason for limiting the amount of wash water added in the second dilution and the caustic soda concentration of the solution in the sodium aluminate crude solution is to control the sodium aluminate concentrate obtained after filtration to be sent to the decomposition process to produce aluminum hydroxide products. If the caustic soda concentration is too high, the seed crystal decomposition rate will be reduced, affecting the product yield, while the second dilution can effectively increase the seed crystal decomposition rate. For example, the mass of the red mud washing water added in the first dilution can account for 55%, 60%, 66.6%, 70%, 72%, 75% and the like of the total mass of the red mud washing water, the mass of the red mud washing water added in the second dilution can account for 25%, 28%, 30%, 32%, 35%, 40%, 45% and the like of the total mass of the red mud washing water, and the caustic soda concentration of the solution in the leached slurry can be 180g / L, 185g / L, 190g / L and 190g / L. g / L, 200g / L, 205g / L, 210g / L, etc. The caustic soda concentration of the solution in the diluted slurry can be 150g / L, 155g / L, 160g / L, 165g / L, 170g / L, 175g / L, 180g / L, etc. The caustic soda concentration of the crude sodium aluminate solution can be 130g / L, 140g / L, 150g / L, 155g / L, 160g / L, etc.

[0044] The reason for limiting the solution molecular ratio is that the difference in molecular ratio between the semen and the dissolution solution is only about 0.03, as secondary dilution can effectively reduce the hydrolysis loss. A lower semen molecular ratio can effectively increase the supersaturation of the sodium aluminate solution and further increase the seed crystal decomposition rate. k It can be 1.33, 1.35, 1.37, 1.40, 1.42, 1.45, etc. The molecular ratio of the solution in the diluted slurry is α k It can be 1.35, 1.36, 1.38, 1.40, 1.42, 1.45, 1.47, etc. The molecular ratio of the solution in the crude sodium aluminate solution is α k It can be 1.36, 1.38, 1.40, 1.42, 1.45, 1.48, etc. The molecular ratio of the solution in sodium aluminate semen is α k It can be 1.36, 1.38, 1.40, 1.42, 1.45, 1.48, etc.

[0045] In some embodiments, the first set temperature is 103° C. to 108° C., and the first set time is 2 hours to 4 hours.

[0046] In some embodiments, the second set temperature is 100° C. to 105° C., and the second set time is 1.5 hours to 2.5 hours.

[0047] Since the temperature of red mud washing water is relatively low, generally 90℃~95℃, taking part of the red mud washing water to dissolve the slurry and mix it can effectively increase the temperature of the slurry during dilution and sedimentation separation. The higher the slurry temperature, the more stable the sodium aluminate solution and the smaller the hydrolysis loss. For example, the first set temperature can be 103℃, 104℃, 105℃, 106℃, 107℃, 108℃, etc., and the first set time can be 2h, 2.5h, 3h, 3.5h, 4h, etc. The second set temperature can be 100℃, 101℃, 102℃, 103℃, 104℃, 105℃, and the second set time can be 1.5h, 1.7h, 1.9h, 2.1h, 2.3h, 2.5h, etc.

[0048] In some embodiments, the suspended matter content of the sodium aluminate semen is <0.015 g / L.

[0049] The reason for limiting the suspended matter content in sodium aluminate semen is that the primary red mud wash water is mixed with the eluate, and the secondary red mud wash water is mixed with the crude liquor, and finally sent to the leaf filter for controlled filtration. This process does not affect the suspended matter content in semen, ensuring that the suspended matter content in semen meets the standard. For example, the suspended matter content in sodium aluminate semen can be 0.014g / L, 0.013g / L, 0.012g / L, 0.011g / L, 0.010g / L, 0.008g / L, etc.

[0050] In some embodiments, in the process of producing alumina using the sodium aluminate concentrate, the molecular ratio difference Δα between the sodium aluminate concentrate and the solution in the dissolution slurry is k It is 0.01~0.04.

[0051] Therefore, the present application provides a method for reducing the hydrolysis loss of sodium aluminate solution, wherein the red mud wash water is diluted twice. After the first dilution, the stability of the solution is not significantly reduced, thereby suppressing the hydrolysis loss during the dilution and separation process. After the second dilution, the solution concentration is further reduced, which can ensure the decomposition rate of the sodium aluminate semen in the subsequent decomposition process.

[0052] The method for reducing hydrolysis loss of sodium aluminate solution provided in this application has significant advantages in suppressing hydrolysis loss, improving decomposition efficiency, and ensuring product quality through innovative process design and parameter optimization, as follows:

[0053] 1. Phased dilution process effectively balances stability and decomposition rate

[0054] (1) Primary dilution to inhibit hydrolysis loss: By controlling 55% to 75% (preferably 65% ​​to 70%) of the red mud washing water for primary dilution, the caustic soda concentration of the diluted slurry is maintained at 150 to 180 g / L, and the molecular ratio α k The higher solution concentration can significantly improve the stability of the sodium aluminate solution, inhibit the crystallization of aluminum hydroxide induced by minerals in red mud, and reduce hydrolysis losses during dilution and sedimentation separation.

[0055] (2) Secondary dilution to ensure decomposition efficiency: The remaining 25% to 45% (preferably 30% to 35%) of the red mud washing water is used for secondary dilution to reduce the caustic soda concentration of the sodium aluminate crude solution to 130 to 160 g / L, and the molecular ratio α k Controlled at 1.36 to 1.48. Low concentration and low molecular weight ratio can increase the supersaturation of the solution, significantly improving the decomposition rate of the subsequent seed decomposition process, while taking into account both hydrolysis inhibition and production efficiency.

[0056] 2. Optimizing temperature and time parameters to improve solution stability

[0057] (1) Maintain high temperature stability by keeping warm once: keep warm at 103-108℃ for 2-4 hours after the first dilution, and use the heat from the mixture of red mud washing water and dissolved slurry to maintain high temperature, so as to avoid the decrease of solution stability due to temperature drop and further inhibit the hydrolysis reaction.

[0058] (2) Secondary insulation takes into account both efficiency and energy consumption: After secondary dilution, the solution is kept at 100-105°C for 1.5-2.5 hours. While ensuring the stability of the solution, the insulation time is shortened to reduce energy consumption and optimize the process economy.

[0059] 3. Concentration and molecular ratio gradient design to accurately control process indicators

[0060] (1) Control of caustic soda concentration gradient: From the dissolution slurry (180-210 g / L) to the diluted slurry (150-180 g / L) and then to the crude sodium aluminate solution (130-160 g / L), the concentration is reduced in a step-by-step manner to avoid a sudden drop in solution stability caused by a one-time dilution, while ensuring that the final semen concentration meets the requirements of the decomposition process.

[0061] (2) Molecular ratio optimization reduces losses: the molecular ratio difference between the dissolved slurry and the semen is only 0.03 (α k 1.33-1.45 and 1.36-1.48 respectively), indicating that the hydrolysis loss is significantly reduced; low molecular ratio semen can increase supersaturation and further improve the decomposition rate, achieving the dual goals of "low loss and high decomposition".

[0062] 4. Product quality and raw material utilization rate are improved simultaneously

[0063] (1) Semen floaters meet the standards: The content of sodium aluminate semen floaters is <0.015g / L. Through two dilutions and controlled filtration processes, the semen purity is ensured to meet production requirements and will not affect the quality of subsequent alumina products.

[0064] (2) Hydrolysis loss is significantly reduced: the molecular ratio difference Δα between the sodium aluminate concentrate and the solution in the slurry k The alumina loss caused by hydrolysis is greatly reduced compared with the traditional process, the utilization rate of raw materials is improved, and the production cost is reduced.

[0065] 5. Outstanding process feasibility and economic advantages

[0066] (1) Strong process compatibility: Based on the improvement of the existing red mud washing and dissolution slurry treatment process, there is no need to significantly modify the equipment. It can be achieved through staged dilution and parameter optimization, and the process feasibility is high.

[0067] (2) Optimization of energy consumption and material costs: The red mud washing water temperature (90-95°C) is used to mix with the dissolved slurry to increase the temperature, thereby reducing the additional heating energy consumption; the washing water volume is accurately controlled to avoid the increase in the subsequent evaporation process load caused by excessive dilution, thereby improving the overall process economy.

[0068] In summary, this application fundamentally solves the contradiction of "low concentration leading to high hydrolysis loss" in the traditional single dilution process through the process innovation of "double dilution + coordinated regulation of temperature-concentration-molecular ratio", and has achieved multiple breakthroughs in inhibiting the hydrolysis of sodium aluminate solution, improving decomposition efficiency, ensuring product quality and reducing production costs, and has significant industrial application value.

[0069] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are generally measured according to industry standards. If there are no corresponding industry standards, then the methods are carried out according to general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0070] This embodiment provides a method for reducing hydrolysis loss of sodium aluminate solution, which may include the following steps:

[0071] S11, mixing a portion of the red mud wash water with the dissolved slurry to perform a primary dilution, and performing a heat preservation treatment with a first set temperature and a first set time to obtain a diluted slurry;

[0072] S21, sedimenting and separating the diluted slurry in a separation sedimentation tank to obtain overflow liquid and red mud;

[0073] S31, mixing the overflow liquid with the remaining portion of the red mud washing water for secondary dilution, and performing a heat preservation treatment with a second set temperature and a second set time to obtain a crude sodium aluminate solution; and

[0074] S41. The crude sodium aluminate solution is subjected to controlled filtration to obtain a sodium aluminate concentrate for seed crystal decomposition. The sodium aluminate concentrate is mixed with the seed crystals and then introduced into a decomposition tank for seed crystal decomposition. Specific process parameters for the method for reducing hydrolysis loss of sodium aluminate solution in the embodiment and comparative example are shown in Table 1.

[0075] Table 1 Specific process parameters of the method for reducing hydrolysis loss of sodium aluminate solution in the embodiment and comparative example

[0076]

[0077] Combined with the data in Table 1, it can be seen that the method provided in Examples 1 to 6 can effectively reduce the hydrolysis loss of sodium aluminate solution, and the molecular ratio difference Δα between the sodium aluminate concentrate and the solution in the dissolution pulp is k It can be reduced from 0.07 to 0.02-0.04, with obvious optimization effect.

[0078] In addition, one or more technical solutions in the embodiments of the present application have at least the following technical effects or advantages:

[0079] In the embodiments of the present application, the method provided is simple and easy to implement. On the one hand, it can improve the stability of the diluted slurry and reduce the hydrolysis loss during the dilution and separation process. On the other hand, the appropriate semen caustic soda concentration and the lower semen molecular ratio can effectively increase the supersaturation of the sodium aluminate solution and further improve the seed crystal decomposition rate.

[0080] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for reducing hydrolysis loss of sodium aluminate solution, the method comprising: Mixing a portion of the red mud wash water with the dissolved slurry for primary dilution, and performing a heat preservation treatment with a first set temperature and a first set time to obtain a diluted slurry; subjecting the diluted slurry to sedimentation separation to obtain overflow liquid; Mixing the overflow liquid with the remaining portion of red mud washing water for secondary dilution, and performing a heat preservation treatment with a second set temperature and a second set time to obtain a crude sodium aluminate solution; as well as performing solid-liquid separation on the crude sodium aluminate liquid to obtain a sodium aluminate fine liquid for seed crystal decomposition; The mass of the red mud washing water added in the first dilution accounts for 55% to 75% of the total mass of the red mud washing water, and the mass of the red mud washing water added in the second dilution accounts for 25% to 45% of the total mass of the red mud washing water.

2. The method according to claim 1, characterized in that The mass of the red mud washing water added in the first dilution accounts for 65% to 70% of the total mass of the red mud washing water, and the mass of the red mud washing water added in the second dilution accounts for 30% to 35% of the total mass of the red mud washing water.

3. The method according to claim 1, characterized in that The caustic soda concentration of the solution in the dissolution slurry is 180g / L to 210g / L, and the molecular ratio of the solution in the dissolution slurry is α k It is 1.33 to 1.

45.

4. The method according to claim 1, wherein The caustic soda concentration of the diluted slurry solution is 150g / L to 180g / L, and the molecular ratio of the diluted slurry solution is α k It is 1.35 to 1.

47.

5. The method according to claim 1, characterized in that The caustic soda concentration of the sodium aluminate crude solution is 130 g / L to 160 g / L, and the molecular ratio of the solution in the sodium aluminate crude solution is α k It is 1.36~1.

48.

6. The method according to claim 1, characterized in that The molecular ratio of the solution in the sodium aluminate semen is α k It is 1.36~1.

48.

7. The method according to claim 1, characterized in that The first set temperature is 103° C. to 108° C., and the first set time is 2 hours to 4 hours.

8. The method according to claim 1, characterized in that The second set temperature is 100° C. to 105° C., and the second set time is 1.5 hours to 2.5 hours.

9. The method according to claim 1, characterized in that The suspended matter content of the sodium aluminate semen is less than 0.015 g / L.

10. The method according to claim 1, characterized in that In the process of producing alumina using the sodium aluminate concentrate, the molecular ratio difference Δα between the sodium aluminate concentrate and the solution in the dissolution pulp is k It is 0.01~0.04.

Images