Deep removal process of aluminum and / or silicon in a high-alkali, low-aluminum, low-silicon solution

Abstract

The present application belongs to the technical field of solution deep purification, and discloses a process for deep removal of aluminum, silicon, aluminum and silicon in a high-alkali, low-aluminum and low-silicon solution. A compound of magnesium or a compound of calcium or a compound of magnesium and calcium is mixed with part of the high-alkali, low-aluminum and low-silicon solution to form a slurry, heated and reacted to obtain an aluminum-removing or silicon-removing or silicon and aluminum-removing additive. The aluminum-removing or silicon-removing or silicon and aluminum-removing additive is added to the high-alkali, low-aluminum and low-silicon solution, heated and reacted to deeply remove aluminum or silicon or silicon and aluminum in the alkali solution. The process has a wide application range, and has a good effect of removing aluminum or silicon or silicon and aluminum, and can realize recycling of the alkali solution.

Description

Technical Field

[0001] This invention belongs to the field of deep solution purification technology, specifically relating to the deep removal of aluminum and / or silicon from high-alkali, low-aluminum, and low-silicon solutions. Background Technology

[0002] In coal chemical deashing processes, direct alkaline leaching can significantly remove ash from coal, yielding high-purity coal with an ash content of less than 1%. However, the alkaline solution after leaching contains aluminum and silicon components, with Al2O3 and SiO2 concentrations of approximately 3–10 g / L, resulting in a very high caustic ratio (a k (The concentration of alkali ions is >80~100). If the alkali solution is directly returned for recycling deashing, it will severely affect the subsequent alkaline leaching deashing effect. Therefore, before the alkali solution enters the recycling deashing process, it is necessary to deeply remove the silicon and aluminum components from the alkali solution. In addition, a large amount of high caustic ratio alkali solution is generated in the alkaline leaching pre-desiliconization of fly ash and the chemical beneficiation of bauxite. The concentration of silicon and aluminum ions in the alkali solution is relatively low. The recycling of the alkali solution requires deep purification to remove the silicon and aluminum components.

[0003] Extensive research has been conducted both domestically and internationally on desilication of strongly alkaline sodium aluminate solutions. The main methods include dilution and heat preservation desilication, desilication by adding sodium silicate slag, and deep desilication by adding lime. However, these desilication methods treat sodium aluminate solutions with high concentrations of alkali and aluminum, typically Na₂O. k The Al2O3 concentrations were all above 100 g / L, even exceeding 200 g / L, and the caustic ratio a k The concentration is typically between 1.4 and 1.8 g / L, while the SiO2 concentration is between 2 and 5 g / L.

[0004] Diluting and heat preservation for desilication refers to adding red mud washing solution to the sodium aluminate slurry after high-temperature dissolution to adjust the Na2O content. k At medium concentration levels (<150 g / L), sodium silicate slag will precipitate due to the decrease in the equilibrium concentration of SiO2 in the diluted solution after being kept at a certain temperature and stirred for a period of time. Although this method is low in cost, its desiliconization efficiency is low and is limited by the equilibrium concentration of sodium silicate slag. The SiO2 concentration in the solution after dilution and desiliconization usually drops to about 0.5~1 g / L.

[0005] The principle of adding sodium silicate residue for desilication is to avoid the difficulty of the formation of hydrated sodium aluminosilicate (sodium silicate residue) crystal nuclei and increase the crystallization surface area, thus improving the desilication speed and depth. The stability order of different forms of hydrated sodium aluminosilicate (Na2O•Al2O3•xSiO2•nH2O) in sodium aluminate solution is as follows: amorphous < A-type zeolite < sodalite (embedded chloride) < nosean (embedded sulfate) < cancrinite (embedded carbonate). Regarding the mechanism of the seed crystal, it is generally considered to be based on crystallographic principles. At the same time, the seed crystal provides active sites, promoting the precipitation of silicate ions in the supersaturated silica solution, so that the silicon in the solution is transferred from the liquid phase to the solid phase for removal. By using this method, the removal of silicon in sodium aluminate solution under normal pressure can be achieved at a relatively low cost.

[0006] Patent CN101397604A discloses a method for purifying alkali liquor after pre-desilication of bauxite by leaching with high-concentration alkali liquor. In this method, by adding sodium silicate residue or red mud waste residue seeds to the alkali liquor and stirring and crystallizing for 1 - 20 hours, most of the silicon dioxide in the alkali liquor can be removed, so that the alkali liquor can be recycled. Among them, the weight ratio of the seed crystal to the alkali solution is 1~3:10. Before desilication, the Al2O3 content in the solution is 22.6 g / L, and the SiO2 content is 21.5 g / L. After desilication, it can be reduced to 7.5 g / L and 6.5 g / L. This method can recycle the alkali liquor for chemical beneficiation desilication of bauxite, but this method only has a certain removal effect on alkali liquor containing high concentrations of silicon and aluminum.

[0007] In the desilication process of adding lime (lime milk) to sodium aluminate solution, calcium aluminate hydrate is first formed, and at the same time, the silicate ions in the solid solution are dissolved to form hydrogarnet (3CaO•Al2O3•xSiO2•(6 - 2x)H2O). Compared with sodium silicate residue, hydrogarnet has a lower equilibrium solubility and better stability in sodium aluminate solution, and can achieve deep desilication of sodium aluminate solution. Under the condition of deep desilication at 85 - 95 °C, the SiO2 concentration in sodium aluminate solution can be reduced to less than 0.1 g / L, and the silicon modulus can be increased to more than 1000. The formation of hydrogarnet reduces the silicon concentration in the solution, achieving the purpose of deep desilication of sodium aluminate solution. The SiO3 2- entering calcium aluminate hydrate and replacing the OH - ions depends on process conditions such as the microstructure of calcium aluminate hydrate, the concentration of silicon dioxide in the solution, the desilication temperature, and the lime addition amount. With the increase of the lime addition amount, the silicon modulus of the desilicated refined liquor can reach a very high value (even 10000), and the SiO2 concentration can even be reduced to less than 0.01 g / L.

[0008] Patent CN1907857A discloses a method for desilication of circulating mother liquor in the Bayer process. This method involves adding lime slurry to the circulating mother liquor (caustic ratio approximately 3) to induce desilication, causing the silicon in the solution to react with the lime slurry to form a calcium-silicon slag precipitate. Solid-liquid separation is then performed, and the separated alkaline solution is concentrated by evaporation and can be reintroduced into the circulating mother liquor system. The suitable solution has a SiO2 concentration of 0.8–1.6 g / L and an Al2O3 content of approximately 90 g / L. The effective calcium addition amount of the lime slurry is 1–20 g / L. The desilication product is hydrated garnet. This method is effective for desilication of alkaline solutions in alumina processes, but because the formation of hydrated garnet requires specific temperature, time, and silicon-aluminum concentrations in the solution, it is not suitable for purifying alkaline solutions containing low concentrations of silicon and aluminum.

[0009] Patent CN117865195A discloses a method for producing alumina involving calcification leaching and causticization cycling. This method mainly includes high-pressure alkali leaching, carbonation decomposition of the leaching solution, and causticization with quicklime. The leaching alkali solution is carbonated to obtain aluminum hydroxide and a carbonation decomposition solution. The aluminum hydroxide is then calcined to obtain alumina. Quicklime is added to the carbonation decomposition solution for causticization, with the amount added calculated based on a molar ratio of calcium oxide in the quicklime to carbonate ions in the carbonation decomposition solution of 1.1:1. After causticization, a recyclable sodium hydroxide solution is obtained. However, this process involves high pressure, carbonation, and calcination, making it cumbersome and energy-intensive.

[0010] Xu Yingpeng et al. (Reference: Synergistic Desilication Effect of Silica Slag and Lime on Silica-Containing Alkali Solution [J]. Journal of Guizhou University (Natural Science Edition), 2020, 37(03):36-41.) Calcinated silica slag at 600°C and then added 25 g / L to the alkali solution for desilication. The concentration of the silica-containing alkali solution was 106 g / L, the initial SiO2 concentration in the solution was 8 g / L, and the desilication rate was 66.67%. When 25 g / L of calcined silica slag and CaO with a calcium-silicon ratio of 1 were added together, the desilication rate reached 93%, and a synergistic desilication effect between CaO and silica slag was found during the desilication process. The desilication alkali solution can be recycled, but this process only purifies the silicon in the silica-containing alkali solution and has problems such as large lime addition, high energy consumption, and low process efficiency.

[0011] Wang Zhongming et al. (Reference: Hydrothermal Synthesis of Wollastonite from Alkali-Containing Sodium Silicate Solution [J]. Bulletin of the Chinese Ceramic Society, 2017, 36(10):3446-3451.) used a hydrothermal synthesis method to prepare wollastonite from a high-caustic-ratio alkaline solution containing silicon under normal pressure. When the concentration of SiO2 in the silicon-containing alkaline solution was controlled at 40 g / L and the concentration of Al2O3 at 0.98 g / L, under the conditions of a calcium-silicon ratio of 1.0, a temperature of 98℃, and a reaction time of 5 h, the precipitation rate of silicon was over 95%, and the calcined product was wollastonite. However, this process only involves the removal of silicon from the alkaline solution and does not consider the simultaneous removal of silicon and aluminum, so it cannot be used for the purification, regeneration, and recycling of coal deashing alkaline solution.

[0012] In summary, existing alkaline solution purification processes involve numerous different solution systems. Sodium aluminate solution purification in alumina production follows a principle of desiliconization only, involving desiliconization with sodium silicate slag and deep desiliconization with calcium silicate slag. High-alkali concentration silicate solutions can be regenerated and recycled by adding lime, purifying the silicate solution by generating wollastonite, with specific requirements for both silica and aluminum concentrations in the solution. However, alkaline solutions obtained from processes such as deep purification of coal leaching for ultrapure carbon materials, pre-desiliconization of fly ash through alkaline leaching, and chemical beneficiation of bauxite all exhibit characteristics of high alkali, low aluminum, and low silica, with high caustic ratios. These solutions vary significantly in composition and structure due to differences in the equilibrium concentrations of sodium silicate slag and calcium silicate slag in the alkaline solution. Therefore, only a portion of the SiO2 in the solution can be removed, and Al2O3 cannot be simultaneously purified and removed. Consequently, secondary alkaline solutions (containing silica and aluminum) cannot be regenerated and recycled. Therefore, how to remove low levels of silicon and aluminum from high-concentration alkaline solutions to achieve purification and regeneration of the alkaline solution is an urgent technical problem that needs to be solved in the field of alkaline solution purification technology. Summary of the Invention

[0013] In view of the problems existing in the prior art, the first objective of the present invention is to provide a deep removal process for aluminum in a high-alkali, low-aluminum, and low-silicon solution; the second objective of the present invention is to provide a deep removal process for silicon in a high-alkali, low-aluminum, and low-silicon solution; and the third objective of the present invention is to provide a deep removal process for both aluminum and silicon in a high-alkali, low-aluminum, and low-silicon solution.

[0014] The high-alkali, low-aluminum, low-silicon solution described in this invention refers to a solution with an Al2O3 concentration of 3-10 g / L, a SiO2 concentration of approximately 3-10 g / L, and a Na2O concentration of approximately 10 g / L. k A solution with a concentration of 100~200g / L.

[0015] To achieve the above objectives, the present invention provides the following specific technical solutions.

[0016] First, this invention provides a deep aluminum removal process from a high-alkali, low-aluminum, low-silicon solution, comprising:

[0017] Step S1: Mix the magnesium compound with a portion of a high-alkali, low-aluminum, and low-silicon solution to form a slurry, heat, and react to obtain an aluminum removal additive.

[0018] Step S2: Add the aluminum removal additive to a high-alkali, low-aluminum, low-silicon solution, heat, and react.

[0019] In a further preferred embodiment, the magnesium compound is at least one of magnesium oxide and magnesium hydroxide.

[0020] In a further preferred embodiment, in step S1, the solid-liquid ratio of the magnesium compound to the high-alkali, low-aluminum, low-silicon solution is 1g:1~3mL.

[0021] In a further preferred embodiment, in step S1, the heating temperature is 20~100℃; the reaction time is 0.5~3h. More preferably, the heating temperature is 40~80℃; the reaction time is 1~2h.

[0022] In a further preferred embodiment, in step S1, after the reaction is completed, solid-liquid separation is performed.

[0023] In a further preferred embodiment, in step S2, 10-20g of the aluminum removal additive, preferably 12-18g, is added to each L of high-alkali, low-aluminum, low-silicon solution.

[0024] In a further preferred embodiment, in step S2, the heating temperature is 50~150℃, preferably 70~110℃; the reaction time is 2~5h, preferably 2~4h.

[0025] In a further preferred embodiment, the process further includes a solid-liquid separation step on the slurry after the reaction in step S2. After solid-liquid separation, aluminum-removed slag and a purified liquid after aluminum removal are obtained. The aluminum-removed slag, after acid washing, can be used as an aluminum removal additive.

[0026] Secondly, this invention provides a deep silicon removal process from a high-alkali, low-aluminum, low-silicon solution, comprising:

[0027] Step S1: Mix the calcium compound with a portion of a high-alkali, low-aluminum, low-silicon solution to form a slurry, heat, and react to obtain a silicon removal additive.

[0028] Step S2: Add the silicon removal additive to a high-alkali, low-aluminum, low-silicon solution, heat, and react.

[0029] In a further preferred embodiment, the calcium compound is at least one of calcium oxide and calcium hydroxide.

[0030] In a further preferred embodiment, in step S1, the solid-liquid ratio of the calcium compound to the high-alkali, low-aluminum, low-silicon solution is 1g:1~3mL.

[0031] In a further preferred embodiment, in step S1, the heating temperature is 20~100℃; the reaction time is 0.5~3h. More preferably, the heating temperature is 40~80℃; the reaction time is 1~2h.

[0032] In a further preferred embodiment, in step S1, after the reaction is completed, solid-liquid separation is performed.

[0033] In a further preferred embodiment, in step S2, 5-20g of a silicon removal additive is added to each L of high-alkali, low-aluminum, low-silicon solution.

[0034] In a further preferred embodiment, in step S2, the heating temperature is 50~150℃, preferably 70~110℃; the reaction time is 2~5h, preferably 2~4h.

[0035] In a further preferred embodiment, the process further includes a solid-liquid separation step on the slurry after the reaction in step S2. After solid-liquid separation, desiliconized slag and a purified liquid after desiliconization are obtained. The desiliconized slag, after acid washing, can be used as a desiliconization additive.

[0036] Based on the same inventive concept, this invention provides a deep removal process for aluminum and silicon in a high-alkali, low-aluminum, low-silicon solution, comprising:

[0037] Step S1: Mix calcium compounds and magnesium compounds with a portion of a high-alkali, low-aluminum, and low-silicon solution to form a slurry, heat, and react to obtain a silicon-aluminum additive.

[0038] Step S2: Add the silicon-aluminum additive to a high-alkali, low-aluminum, low-silicon solution, heat, and react.

[0039] In a further preferred embodiment, the magnesium compound is at least one of magnesium oxide and magnesium hydroxide; the calcium compound is at least one of calcium oxide and calcium hydroxide.

[0040] In a further preferred embodiment, the mass ratio of the calcium compound to the magnesium compound is 1:1 to 1:3.

[0041] In a further preferred embodiment, in step S1, the solid-liquid ratio of the calcium compound, the magnesium compound, and the high-alkali, low-aluminum, low-silicon solution is 1g:1~3mL.

[0042] In a further preferred embodiment, in step S1, the heating temperature is 20~100℃; the reaction time is 0.5~3h. More preferably, the heating temperature is 40~80℃; the reaction time is 1~2h.

[0043] In a further preferred embodiment, in step S1, after the reaction is completed, solid-liquid separation is performed.

[0044] In a further preferred embodiment, in step S2, 10-20g of the desiliconizing aluminum additive is added to each L of high-alkali, low-aluminum, low-silicon solution.

[0045] In a further preferred embodiment, in step S2, the heating temperature is 50~150℃, preferably 70~110℃; the reaction time is 2~5h, preferably 2~4h.

[0046] In a further preferred embodiment, the process further includes a solid-liquid separation step on the slurry after the reaction in step S2. After solid-liquid separation, desiliconized aluminum slag and purified liquid after desiliconization and aluminum removal are obtained. The desiliconized aluminum slag can be used as a desiliconization and aluminum removal additive.

[0047] Compared with the prior art, one or more technical solutions of the present invention can achieve at least one of the following beneficial effects:

[0048] The deep purification process for aluminum and / or silicon provided by this invention has a wide range of applications, including the purification and regeneration of alkaline solutions obtained from coal alkaline leaching and desilication, fly ash pre-desiliconization alkaline solutions, and alkaline solutions obtained from chemical beneficiation of low-grade bauxite.

[0049] This invention can achieve deep removal of aluminum or silicon from high-alkali, low-aluminum, and low-silicon solutions, or simultaneous removal of silicon and aluminum components in one step, thereby achieving deep purification of the alkaline solution. The purified alkaline solution can be recycled.

[0050] This invention provides a complete technical route for alkaline solution regeneration and recycling for coal alkaline leaching and deashing to prepare high-purity carbon, fly ash pre-desiliconization alkaline solution, and low-grade bauxite chemical beneficiation. At the same time, it overcomes the shortcomings of existing alkaline solution purification methods and provides a new purification method for alkaline solution systems with low aluminum, low silicon, and high caustic ratio, realizing a green, economical, and sustainable technical route. Attached Figure Description

[0051] Figure 1 This is a process flow diagram used in an embodiment of the present invention. Detailed Implementation

[0052] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0053] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0054] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0055] The embodiments of the present invention employ, as follows Figure 1 The process flow shown is as follows.

[0056] Example 1

[0057] Alkaline solution: Al₂O₃ concentration 4.89 g / L, SiO₂ concentration 5.78 g / L, Na₂O k It is 175g / L.

[0058] (1) Magnesium oxide and alkaline solution were mixed in a ratio of 1.5 mL: 1.0 g to form a slurry. The mixture was reacted at 40 °C for 2.5 h. After solid-liquid separation, aluminum removal additive was obtained.

[0059] (2) Add 14g of aluminum removal additive to each L of alkaline solution, heat to 90℃ and react for 2h. After solid-liquid separation, aluminum removal slag and aluminum removal purified liquid are obtained.

[0060] The content of silicon and aluminum in the purification solution was tested, and the results were: Al2O3 content was 0.162 g / L, and SiO2 content was 5.47 g / L.

[0061] (3) The aluminum slag is returned to step (2) as an aluminum removal additive after acid washing.

[0062] (4) The purified liquid after aluminum removal is returned for recycling.

[0063] Comparative Example 1

[0064] The difference between Comparative Example 1 and Example 1 is that magnesium oxide is used directly as the aluminum removal agent, and the specific steps include:

[0065] Add 14g of magnesium oxide to each L of alkaline solution, heat to 90℃ and react for 2 hours. After solid-liquid separation, aluminum-removed slag and purified liquid after aluminum removal are obtained.

[0066] The content of silicon and aluminum in the purification solution was tested, and the results were: Al2O3 content was 2.377 g / L, and SiO2 content was 5.62 g / L.

[0067] Example 2

[0068] Alkaline solution: Al2O3 concentration 6.36 g / L, SiO2 concentration 7.54 g / L, Na2O k It is 195g / L.

[0069] (1) Magnesium oxide and alkaline solution were mixed in a ratio of 3 mL: 1 g to form a slurry. The mixture was reacted at 60 °C for 1 h. After solid-liquid separation, aluminum removal additive was obtained.

[0070] (2) Add 10g of aluminum removal additive to each L of alkaline solution, heat to 80℃ and react for 4h. After solid-liquid separation, aluminum removal slag and aluminum removal purified liquid are obtained.

[0071] The content of silicon and aluminum in the purification solution was tested, and the results were: Al2O3 content was 0.143 g / L, and SiO2 content was 7.39 g / L.

[0072] (3) The aluminum slag is returned to step (2) as an aluminum removal additive after acid washing.

[0073] (4) The purified liquid after aluminum removal is returned to the recycling experiment.

[0074] Example 3

[0075] Alkaline solution: Al2O3 concentration 3.78 g / L, SiO2 concentration 4.66 g / L, Na2O k It is 130g / L.

[0076] (1) Magnesium hydroxide and alkaline solution were mixed and slurried at a ratio of 2.5 mL: 1 g L / S, and reacted at 60 °C for 2 h. After solid-liquid separation, aluminum removal additive was obtained.

[0077] (2) Add 16g of aluminum removal additive to each L of alkaline solution, heat to 75℃ and react for 3h. After solid-liquid separation, aluminum removal slag and aluminum removal purified liquid are obtained.

[0078] The content of silicon and aluminum in the purified liquid was tested, and the results were: Al2O3 content was 0.192 g / L, and SiO2 content was 4.39 g / L.

[0079] (3) The aluminum slag is returned to step (2) as an aluminum removal additive after acid washing.

[0080] (4) The purified liquid after aluminum removal is returned for recycling.

[0081] Example 4

[0082] Alkaline solution: Al₂O₃ concentration 4.89 g / L, SiO₂ concentration 5.78 g / L, Na₂O k It is 175g / L.

[0083] (1) Calcium oxide and alkaline solution were mixed in a ratio of 2.5 mL: 1.0 g to form a slurry. The mixture was reacted at 60 °C for 1 h. After solid-liquid separation, a silicon removal additive was obtained.

[0084] (2) Add 9g of desiliconizing additive to each L of alkaline solution, heat to 85℃ and react for 4h. After solid-liquid separation, desiliconized slag and purified liquid after desiliconization are obtained.

[0085] The content of silicon and aluminum in the purification solution was tested, and the results were: Al2O3 content was 4.71 g / L and SiO2 content was 0.124 g / L.

[0086] (3) The desiliconized slag is returned to step (2) as a desiliconized additive after being acid-washed.

[0087] (4) The purified liquid after silicon removal is returned for recycling.

[0088] Comparative Example 2

[0089] The difference between Comparative Example 2 and Example 4 is that calcium oxide was used directly as the silicon removal agent, and the specific steps included:

[0090] (1) Add 9g of calcium oxide to each L of alkaline solution, heat to 85℃ and react for 4h. After solid-liquid separation, obtain silicon-removed slag and silicon-removed purified liquid.

[0091] The content of silicon and aluminum in the purified liquid was tested, and the results were: Al2O3 content was 4.77 g / L and SiO2 content was 2.326 g / L.

[0092] Example 5

[0093] Alkaline solution: Al2O3 concentration 6.36 g / L, SiO2 concentration 7.54 g / L, Na2O k It is 195g / L.

[0094] (1) Calcium oxide and alkaline solution were mixed and prepared in a ratio of 1.5 mL: 1 g L / S, and reacted at 40 °C for 3 h. After solid-liquid separation, silicon removal additive was obtained.

[0095] (2) Add 15g of desiliconizing additive to each L of alkaline solution, heat to 140℃ and react for 1h. After solid-liquid separation, desiliconized slag and purified liquid after desiliconization are obtained.

[0096] The content of silicon and aluminum in the purification solution was tested, and the results were: Al2O3 content was 6.14 g / L and SiO2 content was 0.117 g / L.

[0097] (3) The desiliconized slag is returned to step (2) as a desiliconized additive after being acid-washed.

[0098] (4) The purified liquid after silicon removal is returned to the recycling experiment.

[0099] Example 6

[0100] Alkaline solution: Al2O3 concentration 3.78 g / L, SiO2 concentration 4.66 g / L, Na2O k It is 130g / L.

[0101] (1) Calcium hydroxide and alkaline solution were mixed in a ratio of 2 mL: 1 g to form a slurry. The mixture was reacted at 50 °C for 2 h. After solid-liquid separation, a silicon removal additive was obtained.

[0102] (2) Add 12g of desiliconizing additive to each L of alkaline solution, heat to 95℃ and react for 2h. After solid-liquid separation, desiliconized slag and desiliconized purified liquid are obtained.

[0103] The content of silicon and aluminum in the purification solution was tested, and the results were: Al2O3 content was 3.59 g / L and SiO2 content was 0.141 g / L.

[0104] (3) The desiliconized slag is returned to step (2) as a desiliconized additive after being acid-washed.

[0105] (4) The purified liquid after silicon removal is returned to the recycling experiment.

[0106] Example 7

[0107] Alkaline solution: Al2O3 concentration 8.27 g / L, SiO2 concentration 9.69 g / L, Na2O k It is 150g / L.

[0108] (1) Mix magnesium oxide and calcium hydroxide in a mass ratio of 1:1, then mix them with alkaline solution in a ratio of 2.5 mL: 1.0 g to form a slurry. React at 70 °C for 1.5 h, and after solid-liquid separation, obtain the silicon-aluminum additive.

[0109] (2) Add 12g of silicon-aluminum removal additive to each L of alkaline solution, heat to 90℃ and react for 2.5h. After solid-liquid separation, silicon-aluminum removal slag and silicon-aluminum removal purified liquid are obtained.

[0110] The contents of aluminum and silicon in the purification solution were tested, and the results were: Al2O3 content was 0.052 g / L, and SiO2 content was 0.084 g / L.

[0111] (3) The desiliconized aluminum slag is returned to step (2) as a desiliconizing additive after acid washing.

[0112] (4) The purified liquid after removing silicon and aluminum is returned for recycling.

[0113] Comparative Example 3

[0114] The difference between Comparative Example 3 and Example 7 is that magnesium oxide and calcium hydroxide are used directly as the silica-alumina removal reagents. The specific steps include:

[0115] (1) Add 6g of magnesium oxide and 6g of calcium hydroxide to each L of alkaline solution, heat to 90℃ and react for 2.5h. After solid-liquid separation, obtain silicon-aluminum slag and purified liquid after silicon-aluminum removal.

[0116] The content of silicon and aluminum in the purification solution was tested, and the results were: Al2O3 content was 4.669 g / L and SiO2 content was 3.438 g / L.

[0117] Example 8

[0118] Alkaline solution: Al₂O₃ concentration 3.98 g / L, SiO₂ concentration 4.77 g / L, Na₂O k It is 115g / L.

[0119] (1) Mix magnesium oxide and calcium hydroxide in a mass ratio of 1:2, then mix with alkaline solution in a ratio of 1.5 mL: 1.0 g to form a slurry. React at 40 °C for 2 h, and after solid-liquid separation, obtain the silicon-aluminum additive.

[0120] (2) Add 18g of silicon-aluminum removal additive to each L of alkaline solution, heat to 110℃ and react for 2h. After solid-liquid separation, silicon-aluminum removal slag and silicon-aluminum removal purified liquid are obtained.

[0121] The content of silicon and aluminum in the purification solution was tested, and the results were: Al2O3 content was 0.098 g / L, and SiO2 content was 0.042 g / L.

[0122] (3) The desiliconized aluminum slag is returned to step (2) as a desiliconizing additive after acid washing.

[0123] (4) The purified liquid after removing silicon and aluminum is returned to the recycling experiment.

[0124] Example 9

[0125] Alkaline solution: Al2O3 concentration 6.65 g / L, SiO2 concentration 7.79 g / L, Na2O k It is 135g / L.

[0126] (1) Mix magnesium oxide and calcium hydroxide in a mass ratio of 1:1.5, then mix them with alkaline solution in a ratio of 2 mL:1 g to form a slurry. React at 50°C for 1 h, and after solid-liquid separation, obtain the silicon-aluminum additive.

[0127] (2) Add 14g of silicon-aluminum removal additive to each L of alkaline solution, heat to 100℃ and react for 3h. After solid-liquid separation, silicon-aluminum removal slag and silicon-aluminum removal purified liquid are obtained.

[0128] The content of silicon and aluminum in the purification solution was tested, and the results were: Al2O3 content was 0.037 g / L, and SiO2 content was 0.016 g / L.

[0129] (3) The desiliconized aluminum slag is returned to step (2) as a desiliconized aluminum additive after acid washing.

[0130] (4) The purified liquid after removing silicon and aluminum is returned for recycling.

[0131] Comparing the contents of aluminum, silicon, and aluminum-silicon components in the purified solutions of Example 1 and Comparative Example 1, Example 4 and Comparative Example 2, and Example 7 and Comparative Example 3, it can be seen that: the aluminum removal additive obtained by pretreatment of magnesium compounds with alkaline solution has a better aluminum removal effect than magnesium compounds; the silicon removal additive obtained by pretreatment of calcium compounds with alkaline solution has a better silicon removal effect than calcium compounds; and magnesium and calcium compounds, after alkaline solution pretreatment, can better remove aluminum and silicon from the alkaline solution at a deeper and more simultaneous depth. This is because: by pre-synthesizing magnesium and calcium compounds with high-alkali, low-aluminum, and low-silicon alkaline solutions, aluminum removal additives, silicon removal additives, and aluminum-silicon removal additives are obtained. Under aluminum, silicon, and aluminum-silicon removal conditions, the synthesized additives have an unstable structure, and their internal structure will recombine. The recombination process can form more sites for adsorbing aluminum and silicon in the alkaline solution, which is more effective than directly adding magnesium and calcium compounds, thus achieving deep removal of aluminum and silicon from the solution.

[0132] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A deep aluminum removal process from a high-alkali, low-aluminum, low-silicon solution, wherein the high-alkali, low-aluminum, low-silicon solution refers to a solution with an Al2O3 concentration of 3~10 g / L, a SiO2 concentration of 3~10 g / L, and a Na2O concentration of 10 g / L. k A solution with a concentration of 100~200 g / L, characterized in that... include: Step S1: Mix the magnesium compound with a portion of a high-alkali, low-aluminum, and low-silicon solution to form a slurry, heat, and react to obtain an aluminum removal additive. Step S2: Add the aluminum removal additive to the high-alkali, low-aluminum, low-silicon solution, heat, and react. In step S1, the magnesium compound is at least one of magnesium oxide and magnesium hydroxide; the solid-liquid ratio of the magnesium compound to the high-alkali, low-aluminum, and low-silicon solution is 1g:1~3mL.

2. The deep removal process as described in claim 1, characterized in that, In step S2, 10-20g of the aluminum removal additive is added to every 1L of high-alkali, low-aluminum, and low-silicon solution.

3. The deep removal process as described in claim 1 or 2, characterized in that, In step S1, the temperature reached by heating is 20~100℃; in step S2, the temperature reached by heating is 50~150℃.

4. The deep removal process as described in claim 1 or 2, characterized in that, In step S1, after the reaction is complete, solid-liquid separation is performed.

5. The deep removal process as described in claim 1 or 2, characterized in that, It also includes a step of solid-liquid separation of the slurry after the reaction in step S2; after solid-liquid separation, the resulting slag phase is acid-washed and used for impurity removal in high-alkali, low-alumina, and low-silicon solutions.

6. A deep removal process for silicon from a high-alkali, low-aluminum, low-silicon solution, wherein the high-alkali, low-aluminum, low-silicon solution refers to a solution with an Al2O3 concentration of 3~10 g / L, a SiO2 concentration of 3~10 g / L, and a Na2O concentration of 10 g / L. k A solution with a concentration of 100~200 g / L, characterized in that... include: Step S1: Mix the calcium compound with a portion of a high-alkali, low-aluminum, low-silicon solution to form a slurry, heat, and react to obtain a silicon removal additive. Step S2: Add the silicon removal additive to a high-alkali, low-aluminum, low-silicon solution, heat, and react. In step S1, the calcium compound is at least one of calcium oxide and calcium hydroxide; the solid-liquid ratio of the calcium compound to the high-alkali, low-aluminum, and low-silicon solution is 1g:1~3mL.

7. The deep removal process as described in claim 6, characterized in that, In step S2, 5-20g of the silicon removal additive is added to every 1L of high-alkali, low-aluminum, and low-silicon solution.

8. The deep removal process as described in claim 6 or 7, characterized in that, In step S1, the temperature reached by heating is 20~100℃; in step S2, the temperature reached by heating is 50~150℃.

9. The deep removal process as described in claim 6 or 7, characterized in that, In step S1, after the reaction is complete, solid-liquid separation is performed.

10. The deep removal process as described in claim 6 or 7, characterized in that, It also includes a step of solid-liquid separation of the slurry after the reaction in step S2; after solid-liquid separation, the resulting slag phase is acid-washed and used for impurity removal in high-alkali, low-alumina, and low-silicon solutions.

11. A deep removal process for aluminum and silicon from a high-alkali, low-aluminum, low-silicon solution, wherein the high-alkali, low-aluminum, low-silicon solution refers to a solution with an Al2O3 concentration of 3~10 g / L, a SiO2 concentration of 3~10 g / L, and a Na2O concentration of 10 g / L. k A solution with a concentration of 100~200 g / L, characterized in that... include: Step S1: Mix calcium compounds and magnesium compounds with a portion of a high-alkali, low-aluminum, and low-silicon solution to form a slurry, heat, and react to obtain a silicon-aluminum additive. Step S2: Add the silicon-aluminum additive to the high-alkali, low-aluminum, low-silicon solution, heat, and react. In step S1, the mass ratio of the calcium compound and the magnesium compound is 1:1 to 1:3; the solid-liquid ratio of the calcium compound, the magnesium compound and the high-alkali, low-aluminum, low-silicon solution is 1g:1 to 3mL.

12. The deep removal process as described in claim 11, characterized in that, In step S2, 10-20g of the silicon-aluminum removal additive is added to every 1L of high-alkali, low-aluminum, and low-silicon solution.

13. The deep removal process as described in claim 11 or 12, characterized in that, In step S1, the temperature reached by heating is 20~100℃; in step S2, the temperature reached by heating is 50~150℃.

14. The deep removal process as described in claim 11 or 12, characterized in that, In step S1, after the reaction is complete, solid-liquid separation is performed.

15. The deep removal process as described in claim 11 or 12, characterized in that, It also includes a step of solid-liquid separation of the slurry after the reaction in step S2; after solid-liquid separation, the resulting slag phase is acid-washed and used for impurity removal in high-alkali, low-alumina, and low-silicon solutions.

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