CN115321567A - Method for improving silicon content index of sodium aluminate solution in low-temperature Bayer process - Google Patents
Method for improving silicon content index of sodium aluminate solution in low-temperature Bayer process Download PDFInfo
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- CN115321567A CN115321567A CN202210983239.XA CN202210983239A CN115321567A CN 115321567 A CN115321567 A CN 115321567A CN 202210983239 A CN202210983239 A CN 202210983239A CN 115321567 A CN115321567 A CN 115321567A
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
- C01F7/04—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom
- C01F7/14—Aluminium oxide or hydroxide from alkali metal aluminates
Abstract
The invention particularly relates to a method for improving the silicon content index of a sodium aluminate solution in a low-temperature Bayer process, belonging to the technical field of alumina preparation, and the method comprises the following steps: proportioning bauxite by using a decomposition mother liquor with a set caustic soda concentration to form ore pulp with a set solid content, and then carrying out pre-desiliconization on the ore pulp; mixing the ore pulp subjected to pre-desiliconization and alkali liquor, and then dissolving out to obtain a dissolving-out liquid; diluting and desiliconizing the dissolution liquid to obtain a semen with a preset silicon content index; three desiliconization processes of pre-desiliconization, dissolution and dilution desiliconization are adopted, and meanwhile, the pre-desiliconization process adopts a batching mode of setting the concentration of mother liquor and setting the solid content, so that SiO in the solution can be effectively reduced 2 The concentration, the desiliconization efficiency is obviously improved, and the problem of low silicon index of the existing sodium aluminate solution is solved.
Description
Technical Field
The invention belongs to the technical field of alumina preparation, and particularly relates to a method for improving the silicon content index of a sodium aluminate solution in a low-temperature Bayer process.
Background
In the process of dissolving out, silicon-containing minerals in the bauxite are decomposed by an alkaline solution, enter the solution in the form of sodium silicate, and then react with a sodium aluminate solution to generate sodium-silicon slag, wherein the sodium-silicon slag is easy to separate out on production equipment and pipelines to form scabs, and the heat transfer coefficient is reduced. Therefore, in order to prevent or reduce the silicon slag scab, the industry adds a pre-desiliconization process before the dissolution, and the raw ore pulp is usually stirred for 8 to 12 hours at the temperature of 95 to 105 ℃ so as to ensure that the silicon minerals are converted into sodium silicon slag as completely as possible. The dissolved ore pulp is diluted by red mud washing liquor, the sodium aluminate solution is further desiliconized, and the silicon content index of the refined solution can reach more than 200.
In recent years, along with the reduction of the reserves and the grade of domestic bauxite, a plurality of domestic alumina enterprises begin to adopt a low-temperature Bayer process dissolution process to treat imported gibbsite, wherein SiO in the imported gibbsite is 2 Is generally low, especially in the Guinea mine SiO 2 The content of the silicon-containing kaolin is lower than 3 percent, the content of the kaolinite is lower than 3 percent, and the silicon content index of the refined solution is generally lower and is only about 150 only by the traditional pre-desiliconization and dilution desiliconization processes. The lower silicon content index of the refined liquid is easy to cause the silicon content in the aluminum hydroxide product to exceed the standard, and the scabbing rate is accelerated. Therefore, a method for effectively improving the silicon content index of the sodium aluminate solution in the low-temperature Bayer process digestion process of the low-activity imported silicon ores must be found.
In the prior art, for example, the chinese patent application CN102491386 is a method for improving the silica index of bayer process concentrate, which is to add a calcium-containing compound into diluted ore pulp after post-thickening and dissolution to perform desiliconization, thereby obtaining sodium aluminate concentrate with the silica index greater than 240. Although the method can improve the silicon content index of the sodium aluminate solution, the calcium-containing compound can react with the sodium aluminate solution to cause alumina loss. For example, the Chinese patent application CN1442361A is a crude liquor desiliconization method for producing alumina and the Chinese patent application CN101857254A is a desiliconization method for high-concentration sodium aluminate solution, mainly aiming at the desiliconization of sodium aluminate solution in the sintering process, and not applicable to the Bayer process dissolution process of gibbsite ore. For example, the Chinese patent application CN102234121A, which is a patent of the invention, is a method and a device for high-solid content pre-desiliconization, and the patent mentions that the desiliconization efficiency can be improved by adopting the high-solid content pre-desiliconization method. However, the test results show that the low-temperature Bayer process treats SiO 2 By only increasing the amount of the mineral in the imported oreThe pre-desiliconization solid content, the silicon content index of the semen is still low.
Disclosure of Invention
The application aims to provide a method for improving the silicon content index of a sodium aluminate solution in a low-temperature Bayer process, so as to solve the problem that the silicon content index of the existing sodium aluminate solution is not high.
The embodiment of the invention provides a method for improving the silicon content index of a sodium aluminate solution in a low-temperature Bayer process, which comprises the following steps:
proportioning bauxite by using a decomposition mother liquor with a set caustic soda concentration to form ore pulp with a set solid content, and then carrying out pre-desiliconization on the ore pulp;
mixing the ore pulp subjected to pre-desiliconization with alkali liquor, and then dissolving out to obtain a dissolving-out liquid;
and diluting and desiliconizing the dissolution liquid to obtain the semen with the preset silicon content index.
Optionally, the concentration of caustic soda is set to be 140-160g/L; the caustic ratio of the decomposition mother liquor, ak, is in the range of 2.6 to 3.0.
Optionally, the set solid content is 400-1000g/L.
Optionally, the temperature of the pre-desiliconization is 95-105 ℃; and/or
The time of the pre-desiliconization is 8-12h.
Optionally, the molecular ratio of the dissolution liquid is 1.30-1.50.
Optionally, the dissolution temperature is 140-150 ℃; and/or
The dissolution time is not less than 30min.
Optionally, the diluting and desiliconizing the dissolution liquid to obtain the semen with the preset silicon content index specifically includes:
diluting and desiliconizing the dissolution liquid, and adding desiliconized seed crystals in the diluting and desiliconizing process to obtain a fine liquid with a preset silicon content index;
wherein the desiliconized seed crystal is Bayer process red mud; and/or
The mass content of sodium-silicon slag in the Bayer process red mud is more than 20 percent; and/or
The addition amount of the Bayer process red mud is 20-100g/L.
Optionally, the temperature of the dilution desilication is 95-105 ℃; and/or
The time for diluting and desiliconizing is more than 2h.
Optionally, the bauxite comprises gibbsite, and the kaolinite mass content of the gibbsite is less than 3%.
Optionally, the preset silicon content index is greater than 200.
One or more technical solutions in the embodiments of the present invention at least have the following technical effects or advantages:
the method for improving the silicon content index of the sodium aluminate solution in the low-temperature Bayer process provided by the embodiment of the invention adopts three desiliconization processes of pre-desiliconization, dissolution and dilution desiliconization, and simultaneously adopts a batching mode of setting the concentration of mother liquor and setting the solid content in the pre-desiliconization process, so that SiO in the solution can be effectively reduced 2 The concentration, the desiliconization efficiency is obviously improved, and the problem that the silicon content index of the sodium aluminate solution is not high at present is solved.
The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
FIG. 1 is a process flow diagram provided by an embodiment of the present invention;
fig. 2 is a flow chart of a method provided by an embodiment of the invention.
Detailed Description
The present invention will be described in detail below with reference to specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly apparent therefrom. It will be understood by those skilled in the art that these specific embodiments and examples are for the purpose of illustrating the invention and are not to be construed as limiting the invention.
Throughout the specification, unless otherwise specifically noted, terms used herein should be understood as having meanings as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. If there is a conflict, the present specification will control.
Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.
In order to solve the technical problems, the general idea of the embodiment of the application is as follows:
the invention aims to provide a method for improving the silicon content index of a sodium aluminate solution in the low-temperature Bayer process digestion process of low-activity silicon imported ore, which can effectively improve the silicon content index of the sodium aluminate solution, meet the requirement of seed crystal decomposition and slow down the scarring rate of an evaporation process.
According to an exemplary embodiment of the present invention, there is provided a method for increasing the silicon content index of a sodium aluminate solution in a low temperature bayer process, the method comprising:
s1, proportioning bauxite by using a decomposition mother liquor with a set caustic soda concentration to form ore pulp with a set solid content, and then carrying out pre-desiliconization on the ore pulp;
in some embodiments, the bauxite comprises gibbsite having a kaolinite mass content of < 3%, in particular, low active silicon content bauxite such as guinea ore.
The higher the kaolinite content in the bauxite, the higher the silicon content index of the sodium aluminate solution in the system; the lower the kaolinite content, the lower the silica index of the sodium aluminate solution in the system; the method is suitable for bauxite with low kaolinite content, namely the kaolinite content is less than 3 percent, certainly, the method cannot be adopted when the kaolinite content is more than or equal to 3 percent, the higher silicon content index can be achieved even if the method is not adopted when the kaolinite content is more than or equal to 3 percent, and the method can be adopted for processing if the method is used for pursuing the higher silicon content index.
In some embodiments, the set caustic concentration is 140-160g/L; the caustic ratio of the decomposition mother liquor, ak, is in the range of 2.6 to 3.0.
The conventional operation in the production process of the alumina adopts the circulating mother liquor for batching, the concentration of caustic soda is about 200-250 g/L, but aiming at the bauxite with low silicon content, siO in the solution in the system is caused 2 The higher concentration, the lower silicon index, due to SiO 2 The concentration is in direct proportion to the caustic alkali concentration, so that the reduction of the caustic alkali concentration of the batching mother liquor is beneficial to the reduction of SiO in the solution 2 And (4) concentration. The method can adopt the decomposition mother liquor for proportioning because the concentration of caustic soda of the decomposition mother liquor is lower, and the decomposition mother liquor is generally 140-160g/L in the process of producing alumina by imported ore. It can be understood that the circulating mother liquor can meet the requirement of lower caustic soda concentration, and can be used as an ingredient, and the lower caustic soda concentration can reach 140-160 g/L.
In some embodiments, the set solids content is 400-1000g/L; the temperature of the pre-desiliconization is 95-105 ℃; the time of the pre-desiliconization is 8-12h.
The solid content is controlled to be 400-1000g/L, the higher the pre-desiliconization solid content is, the higher the silicon content in unit volume is, the more beneficial to desiliconization is, therefore, the solid content is suggested to be more than 400, in other words, the solid content below 400 cannot be realized, only certain desiliconization difficulty is increased, desiliconization can be realized by changing other parameters, when the solid content is more than 1000, the ore pulp has too high viscosity and poor fluidity and is not beneficial to ore pulp conveying, and the solid content value more than 1000 is generally not adopted, of course, the parameter only aims at the current conveying condition, and if a better ore pulp conveying mode is adopted, the ore pulp with high viscosity and poor fluidity can be conveyed, and the solid content value can be correspondingly increased.
The temperature of the pre-desiliconization is controlled to be 95-105 ℃, and if the temperature is lower than 95 ℃, the desiliconization effect can be influenced to a certain extent, but a certain effect can still be generated; if the desiliconization effect is higher than 105 ℃, the desiliconization effect is difficult to be continuously improved, resulting in unnecessary energy consumption, and it is understood that the temperature of the preliminary desiliconization can be further increased, for example, 150 ℃, 200 ℃ or the like, if the energy consumption is not considered.
The time of the pre-desiliconization is controlled to be 8-12h, the desiliconization is incomplete when the time of the pre-desiliconization is less than 8h, the desiliconization effect is not continuously improved when the time of the pre-desiliconization exceeds 12h, and unnecessary energy consumption is caused, and it can be understood that the time of the pre-desiliconization can be further increased if the energy consumption is not considered, for example, 18h, 24h and the like.
S2, mixing the ore pulp subjected to pre-desiliconization with alkali liquor, and then dissolving out to obtain a dissolving-out liquid;
the pre-desiliconized pulp needs to be dosed with a suitable high concentration circulating lye before dissolution to obtain a dissolution liquid, which in some embodiments has a molecular ratio of 1.30-1.50. It should be noted that the molecular ratio of the digestion solution is a term of art in the alumina production process, i.e. the molecular ratio of the digestion solution = Na 2 O/Al 2 O 3 *1.645。
Controlling the molecular ratio of the dissolution liquid to be 1.30-1.50, if the molecular ratio is lower than 1.30, the sodium aluminate solution is unstable and is easy to separate out in the subsequent operation process, and it can be understood that although the decomposition and the separation are easy to cause, the whole scheme can still be realized, but the better effect cannot be achieved; if the molecular ratio is higher than 1.5, the subsequent decomposition power is insufficient, which is not beneficial to the seed crystal decomposition process, and it can be understood that some means can be adopted to solve the problem of insufficient decomposition power, and the molecular ratio of the dissolution liquid is not limited by the above, and can be 1.8, 2.1, and the like.
In some embodiments, the temperature of the dissolution is 140-150 ℃; the dissolution time is not less than 30min.
The low-temperature Bayer process digestion process is generally adopted for the imported gibbsite ore, the digestion temperature is about 145 ℃ (140-150 ℃), the digestion temperature is lower than 140 ℃, alumina is incompletely digested or longer digestion time is needed, it can be understood that the lower digestion temperature can also achieve corresponding effects, only unnecessary time waste and other influences are caused, the digestion rate of alumina is not improved but energy consumption is increased when the lower digestion temperature is higher than 150 ℃, and it can be understood that the digestion temperature can be further increased, such as 160 ℃, 180 ℃ and the like, if energy consumption is not considered. The dissolution time is less than 30min, the dissolution rate of the alumina is not greatly influenced, but the desilication reaction is not favorably carried out, the dissolution time is prolonged to be more than 30min, the desilication is favorably carried out, and the silicon content index is improved.
And S3, diluting and desiliconizing the dissolved ore pulp to obtain a refined liquid with a preset silicon content index.
In some embodiments, the dilute desiliconized seed crystal is bayer process red mud, and in particular, may be selected from domestic ore bayer process red mud; the mass content of sodium-silicon slag in the Bayer process red mud is more than 20 percent; the addition amount of the Bayer process red mud is 20-100g/L.
The domestic ore is characterized in that the high-aluminum high-silicon sodium-silicon slag is produced after the silicon mineral is dissolved out at high temperature, the sodium-silicon slag is added into a dilution desilication tank as a crystal seed to induce the generation of new sodium-silicon slag, and the SiO in the solution is reduced 2 Concentration, and silicon content index is improved. In the invention process, the applicant finds that the content of sodium-silicon slag is more than 20%, the desiliconization effect is better, and the silicon content index can reach more than 200.
Except for the requirement that the content of sodium-silicon slag in the red mud is more than 20 percent, the amount of the red mud is also an important parameter, and the desiliconization effect is also poor due to too small addition amount; too much red mud is added, the amount of the red mud is increased, the operation of a subsequent sedimentation process is not facilitated, and it can be understood that the effect is obtained on the basis of using a conventional sedimentation process, and if a sedimentation process with better effect is adopted, the addition amount of the red mud can be further increased, such as 150g/L, 200g/L and the like.
In some embodiments, the temperature of the dilute desilication is 95-105 ℃; the time for diluting and desiliconizing is more than 2h.
The process conditions of dilution and desilication are basically consistent with those of the prior art, the high temperature and the enough long time are ensured, the desilication reaction can be carried out more fully, and the silicon content index can be effectively improved.
In some embodiments, the predetermined silicon index is > 200.
By adopting the design, the problem that the silicon content in the low-temperature dissolution process of imported gibbsite ore with lower active silicon content, such as Guinei ore, can be effectively solvedThe number is low. Firstly, the pre-desiliconization process adopts a batching mode of low mother liquor concentration (namely caustic soda concentration of decomposed mother liquor) and high solid content, and can effectively reduce SiO in the solution 2 The concentration obviously improves the desiliconization efficiency; secondly, high-concentration alkali liquor is added again in the dissolution process, so that the dissolution effect is ensured; and finally, in the process of dilution and desilication, bayer process red mud is added again as desilication crystal seeds, so that the silicon index of the sodium aluminate solution is further ensured to reach more than 200, the requirement of crystal seed decomposition on the silicon index of the sodium aluminate solution is met, the scab rate of an evaporation process is slowed down, the production energy consumption of alumina is reduced, and good economic benefit and social benefit are achieved.
The method for improving the silicon content index of the sodium aluminate solution in the low-temperature Bayer process is described in detail below by combining examples, comparative examples and experimental data.
Example 1
A method for improving the silicon content index of a sodium aluminate solution in a low-temperature Bayer process comprises the following steps:
the test was carried out using 1# imported ore (kaolinite content 1.5%): firstly, pre-desiliconizing is carried out under the conditions that the concentration of decomposition mother liquor is 145g/l, the temperature is 95 ℃, the time is 10 hours and the solid content is 600 g/l; then supplementing 240g/l of circulating mother liquor into the pre-desiliconized ore pulp, and dissolving out for 1h at 145 ℃; adding hot water into the dissolved ore pulp for dilution, wherein the concentration of caustic soda after dilution is 145g/l, then adding the ground Bayer process red mud (the content of sodium-silicon slag is about 26 percent) of the domestic ore into the diluted ore pulp, wherein the adding amount is 100g/l, and stirring for 3 hours at the temperature of 95 ℃ to obtain refined solution.
Example 2
A method for improving the silicon content index of a sodium aluminate solution in a low-temperature Bayer process comprises the following steps:
the test was carried out using # 1 imported ore (kaolinite content 1.5%): firstly, carrying out pre-desiliconization under the conditions of 155g/l concentration of decomposition mother liquor, 105 ℃ temperature, 10h time and 600g/l solid content; then supplementing 230g/l of circulating mother liquor into the pre-desiliconized ore pulp, and dissolving out for 1h at 145 ℃; adding hot water into the dissolved ore pulp for dilution, wherein the concentration of caustic soda is 145g/l, adding the grinded Bayer process red mud (the content of sodium-silicon slag is about 26%) of domestic ore into the diluted ore pulp, the adding amount is 50g/l, and stirring for 3h under the condition of a temperature of 105 ℃ to obtain refined liquid
Example 3
A method for improving the silicon content index of a sodium aluminate solution in a low-temperature Bayer process comprises the following steps:
adopts 1# imported ore (SiO) 2 Content 1.5%) were tested: firstly, carrying out pre-desiliconization under the conditions of 145g/l of decomposition mother liquor concentration, 105 ℃ of temperature, 12 hours of time and 800g/l of solid content; then supplementing 240g/l of circulating mother liquor into the pre-desiliconized ore pulp, and dissolving out for 1h at 145 ℃; adding hot water into the dissolved ore pulp for dilution, wherein the concentration of caustic soda after dilution is 145g/l, then adding the ground Bayer process red mud (the content of sodium-silicon slag is about 26 percent) of the domestic ore into the diluted ore pulp, wherein the adding amount is 100g/l, and stirring for 3 hours at the temperature of 105 ℃ to obtain refined solution.
Example 4
A method for improving the silicon content index of a sodium aluminate solution in a low-temperature Bayer process comprises the following steps:
the test was carried out using imported ore # 2 (kaolinite content 2.5%): firstly, carrying out pre-desiliconization under the conditions of the concentration of decomposition mother liquor of 155g/l, the temperature of 105 ℃, the time of 12h and the solid content of 1000g/l; then supplementing 230g/l of circulating mother liquor into the pre-desiliconized ore pulp, and dissolving out for 1h at 145 ℃; adding hot water into the dissolved ore pulp for dilution, wherein the concentration of diluted caustic soda is 150g/l, then adding the ground Bayer process red mud (the content of sodium-silicon slag is about 20%) of domestic ores into the diluted ore pulp, wherein the adding amount is 50g/l, and stirring for 3h under the condition of the temperature of 105 ℃ to obtain refined solution.
Example 5
A method for improving the silicon content index of a sodium aluminate solution in a low-temperature Bayer process comprises the following steps:
the test was carried out using imported ore # 2 (kaolinite content 2.5%): firstly, pre-desiliconizing is carried out under the conditions that the concentration of decomposed mother liquor is 150g/l, the temperature is 105 ℃, the time is 12 hours and the solid content is 600 g/l; then supplementing 235g/l of circulating mother liquor into the pre-desiliconized ore pulp, and dissolving out for 30min at 145 ℃; adding hot water into the dissolved ore pulp for dilution, wherein the concentration of diluted caustic soda is 150g/l, then adding the ground Bayer process red mud (the content of sodium-silicon slag is about 20%) of the domestic ore into the diluted ore pulp, wherein the adding amount is 100g/l, and stirring for 3 hours at the temperature of 105 ℃ to obtain refined solution.
Example 6
A method for improving the silicon content index of a sodium aluminate solution in a low-temperature Bayer process comprises the following steps:
the test was carried out using # 2 imported ore (2.5% kaolinite content): firstly, carrying out pre-desiliconization under the conditions of 155g/l concentration of decomposition mother liquor, 105 ℃ temperature, 12h time and 800g/l solid content; then supplementing 230g/l of circulating mother liquor into the pre-desiliconized ore pulp, and dissolving out for 1.5h at 145 ℃; adding hot water into the dissolved ore pulp for dilution, wherein the concentration of diluted caustic soda is 150g/l, then adding the ground Bayer process red mud (the content of sodium-silicon slag is about 20%) of the domestic ore into the diluted ore pulp, wherein the adding amount is 100g/l, and stirring for 3 hours at the temperature of 105 ℃ to obtain refined solution.
Comparative example 1
The same imported ore as that used in the comparative example and example 1 was used, specifically:
the conventional test was carried out using 1# imported ore (kaolinite content 1.5%): firstly, carrying out pre-desiliconization on circulating mother liquor under the conditions of caustic soda concentration of 230g/L, pre-desiliconization temperature of 90 ℃, time of 8h and solid content of 350g/L, then dissolving out for 1h at 145 ℃, diluting ore pulp after dissolving out, keeping the caustic soda concentration of 160g/L and the dilution temperature of 95 ℃, and stirring for 2h under heat preservation to obtain refined solution.
Comparative example 2
The same imported ore of this comparative example and example 4, specifically:
the conventional test was carried out using imported ore # 2 (kaolinite content 2.5%): firstly, carrying out pre-desiliconization on circulating mother liquor under the conditions of caustic soda concentration of 230g/L, pre-desiliconization temperature of 95 ℃, time of 8h and solid content of 400g/L, then dissolving out for 1h at 145 ℃, diluting ore pulp after dissolving out, keeping the caustic soda concentration of 160g/L and the dilution temperature of 95 ℃, and stirring for 2h under heat preservation to obtain refined solution.
Related experiments:
the semen obtained in examples 1 to 6 and comparative examples 1 to 2 was analyzed, and the results are shown in the following table.
| Silicon content index of semen g/L | |
| Example 1 | 212 |
| Example 2 | 208 |
| Example 3 | 221 |
| Example 4 | 210 |
| Example 5 | 198 |
| Example 6 | 210 |
| Comparative example 1 | 146 |
| Comparative example 2 | 165 |
From the above table, the method provided by the embodiment of the application is adopted to carry out Bayer process dissolution on low-activity imported silicon ores, the silicon content index of the final sodium aluminate refined solution reaches more than 198g/L, and the silicon content index of the final sodium aluminate refined solution hardly exceeds 170g/L by adopting the conventional method for treatment.
Finally, it should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (10)
1. A method for increasing the silicon content index of a sodium aluminate solution in a low temperature bayer process, the method comprising:
proportioning bauxite by using a decomposition mother liquor with a set caustic soda concentration to form ore pulp with a set solid content, and then carrying out pre-desiliconization on the ore pulp;
mixing the ore pulp subjected to pre-desiliconization with alkali liquor, and then dissolving out to obtain a dissolving-out liquid;
and diluting and desiliconizing the dissolution liquid to obtain the semen with the preset silicon content index.
2. The method for improving the silicon content index of a sodium aluminate solution in a low-temperature Bayer process according to claim 1, wherein the set caustic concentration is 140-160g/L; the caustic ratio of the decomposition mother liquor, ak, is in the range of 2.6 to 3.0.
3. The method for improving the silicon content index of a sodium aluminate solution in a low-temperature Bayer process according to claim 1, wherein the set solid content is 400-1000g/L.
4. The method for improving the silicon content index of a sodium aluminate solution in a low-temperature Bayer process according to claim 1, wherein the temperature of the pre-desilication is 95-105 ℃; and/or
The time of the pre-desiliconization is 8-12h.
5. The method for improving the silicon content index of a sodium aluminate solution in a low temperature bayer process according to claim 1, wherein the leachant has a molecular ratio of 1.30 to 1.50.
6. The method for improving the silicon content index of a sodium aluminate solution in a low temperature bayer process according to claim 1, wherein the temperature of the dissolution is 140 ℃ to 150 ℃; and/or
The dissolution time is not less than 30min.
7. The method for improving the silicon content index of the sodium aluminate solution in the low-temperature Bayer process as claimed in claim 1, wherein the dilution desilication is performed on the leachate to obtain the refined solution with the preset silicon content index, and the method specifically comprises the following steps:
diluting and desiliconizing the dissolution liquid, and adding desiliconized seed crystals in the diluting and desiliconizing process to obtain a refined liquid with a preset silicon content index;
wherein the desiliconization crystal seed is Bayer process red mud; and/or
The mass content of sodium-silicon slag in the Bayer process red mud is more than 20 percent; and/or
The addition amount of the Bayer process red mud is 20-100g/L.
8. The method for improving the silicon content index of a sodium aluminate solution in a low-temperature Bayer process according to claim 1, wherein the temperature of the dilution desilication is 95-105 ℃; and/or
The time for diluting and desiliconizing is more than 2h.
9. The method of increasing the silicon content index of a sodium aluminate solution in a low temperature bayer process of claim 1, wherein the bauxite comprises gibbsite having a kaolinite mass content of < 3%.
10. The method for improving the silicon content index of a sodium aluminate solution in a low temperature bayer process according to claim 1, wherein the predetermined silicon content index is > 200.
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