Method for preparing nano-aluminum silicate using mixed alkali and refined slag

Abstract

The invention belongs to the technical field of repeated utilization of solid waste resources, and discloses a method for preparing nano-aluminum silicate by using mixed alkali and refined slag. The method comprises the following steps: S1, preparing a mixed alkali solution; S2, mixing the carbonated refined slag and the mixed alkali solution to form a suspension; S3, stirring, filtering, and removing the slag from the suspension to obtain a filtrate; S4, adding water glass to the filtrate and shaking it to form a sol; S5, centrifuging the sol; washing the separated solid components to adjust the pH; S6, fully dissolving the solid in an oxalic acid solution to obtain a suspension; S7, aging the suspension to obtain a gel, and freezing, drying, and crushing the gel to obtain nano-aluminum silicate powder. The invention uses the mixed alkali to extract silicon and aluminum from the carbonated refined slag, and then adjusts the silicon-to-aluminum ratio by adding water glass, so that the obtained nano-scale amorphous nano-aluminum silicate particles are uniform, high in purity, and large in specific surface area.

Description

Technical Field

[0001] The invention relates to the technical field of repeated utilization of solid waste resources, and specifically to a method for preparing nano-aluminum silicate by utilizing mixed alkali and refined slag. Background Art

[0002] Metallurgical solid waste is generated during the metallurgical production process. Solid waste, or metallurgical solid waste, primarily consists of blast furnace slag, steel slag, non-ferrous metal slag (generated during the smelting of non-ferrous metals, such as copper slag, lead slag, zinc slag, nickel slag, and aluminum slag), and iron oxide slag (generated during steel rolling). Refined slag is a type of slag discharged from the steel industry. However, the current resource utilization of refined slag is relatively limited and low-value, primarily being mixed with converter slag for use in the production of building materials. For example, a Chinese patent (Patent Publication No.: CN111499228B) discloses a cementitious material for mortar and its use, specifically disclosing the preparation of the cementitious material by pre-doping steel slag and then grinding it. A Chinese patent (Patent Publication No.: CN104386929B) discloses a method for producing cementitious material using steel slag and the cementitious material, specifically disclosing the preparation of the cementitious material by grinding steel slag, fine aggregate, and an activator. However, the resource value of Al and Si in refined slag is not reflected.

[0003] A Chinese patent (Patent Publication No. CN101402460) discloses a method for producing aluminum silicate using LF furnace refined slag. However, this method requires strong acid leaching, which places high demands on the corrosion resistance of the equipment and results in the dissolution of a large amount of impurities. Furthermore, there is a lack of data supporting the particle size and specific surface area of the aluminum silicate particles produced. Similar issues also exist in the preparation of ultrafine aluminum silicate using blast furnace slag reported in another paper (Chu Liang. Research on the Preparation of Ultrafine Aluminum Silicate and Magnesium Aluminum Spinel from Blast Furnace Slag. Master's Thesis, Anhui University of Technology, 2011). Summary of the Invention

[0004] The present invention aims to provide a method for preparing nano-aluminum silicate using mixed alkali and refined slag. The mixed alkali (NaOH and Na2CO3) is used to extract silicon and aluminum from the carbonated refined slag, and then the silicon-aluminum ratio is adjusted by adding water glass. After that, through sol-gel, filtration, washing, aging, freeze-drying and other process flows, nano-scale amorphous nano-aluminum silicate with high purity, uniform particles and large specific surface area is obtained. The nano-aluminum silicate can be widely used in related industries such as coatings, inks, plastics, rubber, leather, printing and dyeing, and papermaking, and has high industrial utilization value.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The method for preparing nano-aluminum silicate by using mixed alkali and refined slag comprises the following steps:

[0007] S1, prepare NaOH and Na2CO3 mixed alkali solution;

[0008] S2, mixing the carbonated refined slag and the mixed alkali solution obtained in step S1 at a mass ratio of 1:5 to 1:15 to form a suspension;

[0009] S3, stirring the suspension obtained in step S2, filtering after stirring, and removing the filter residue to obtain a filtrate;

[0010] S4, adding water glass to the filtrate obtained in step S3 and shaking to form a sol;

[0011] S5, centrifuging the sol obtained in step S4; washing the separated solid component thoroughly to adjust its pH, and recycling the separated water to prepare the mixed alkali solution in step S1;

[0012] S6, dissolving oxalic acid in water to prepare an oxalic acid solution, and fully dissolving the solid obtained by washing in step S5 in the oxalic acid solution to obtain a suspension; wherein the mass ratio of the solid component to the oxalic acid solution is 1:3 to 1:6;

[0013] S7. Aging the suspension obtained in step S6 to obtain a gel, and freezing, drying and crushing the gel to obtain nano-aluminum silicate powder.

[0014] Furthermore, in S1, the concentration of NaOH in the prepared mixed alkali solution is 2-4 mol / L; the concentration of Na2CO3 is 0.5-1.5 mol / L.

[0015] Furthermore, in S3, the suspension is stirred at a temperature of 40 to 80° C. for 40 to 60 minutes.

[0016] Furthermore, in S4, the composition of water glass by mass is: H2O accounts for 50-60%, Na2O accounts for 10-20%, and SiO2 accounts for 20-40%; the amount of water glass added is 15%-30% of the mass of the filtrate; the shaking conditions after adding water glass are: shaking at a temperature of 70-80°C for 1.5-2h.

[0017] Furthermore, in S5 , the separated solid component is washed and then adjusted to a pH value between 6.5 and 7.5.

[0018] Furthermore, in S6, the pH value of the prepared oxalic acid solution is between 5.5 and 6.0.

[0019] Furthermore, in S7, the conditions for aging the suspension to obtain a gel are: aging at room temperature for 24 to 48 hours; the conditions for freezing the gel are: freezing at -80°C to 20°C for 12 to 24 hours; and the conditions for drying are: drying in a freeze dryer for 5 to 12 hours.

[0020] The beneficial effects of the technical solution are:

[0021] 1. The present invention utilizes NaOH and Na2CO3 to extract silicon and aluminum from carbonated refined slag, thereby providing an effective way to utilize the refined slag, especially the carbonated refined slag obtained by a treatment method for carbonation desulfurization of steelmaking refined slag according to a Chinese patent (publication number: CN110527758B), thereby achieving comprehensive utilization of secondary resources, realizing a circular economy, and energy conservation and emission reduction.

[0022] 2. The preparation method provided by the present invention has simple process and equipment, low cost, easy and safe operation;

[0023] 3. The nano-scale amorphous nano-aluminum silicate prepared by the present invention has high purity and large specific surface area, and can be widely used in coatings, inks, plastics, rubber, leather, printing and dyeing, papermaking and other related industries, and has high industrial utilization value. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a SEM image of nano-aluminum silicate obtained in Example 1 of the present invention;

[0025] Figure 2 This is a SEM image of nano-aluminum silicate obtained in Example 2 of the present invention;

[0026] Figure 3 This is a graph showing the test results of the BET specific surface area of nano-aluminum silicate obtained in Example 2 of the present invention;

[0027] Figure 4 The whiteness data of the nano-aluminum silicate obtained in Example 2 of the present invention was measured using a whiteness meter. DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0029] The method for preparing nano-aluminum silicate by using mixed alkali and refined slag comprises the following steps:

[0030] S1. Mix 2-4 mol / L NaOH and 0.5-1.5 mol / L Na2CO3 to prepare a mixed alkali solution;

[0031] S2, mixing the carbonated refined slag and the mixed alkali solution obtained in step S1 at a mass ratio of 1:5 to 1:15 to form a suspension;

[0032] S3, stirring the suspension obtained in step S2, stirring at a temperature of 40 to 80° C. for 40 to 60 minutes, and then filtering to remove the filter residue to obtain a filtrate;

[0033] S4. Add water glass to the filtrate obtained in step S3 and shake it at 70-80° C. for 1.5-2 hours to form a sol; wherein the composition of the water glass is as follows by mass: H2O accounts for 50-60%, Na2O accounts for 10-20%, and SiO2 accounts for 20-40%; the amount of water glass added is 15%-30% of the mass of the filtrate;

[0034] S5, centrifuging the sol obtained in step S4; washing the separated solid component three times to adjust its pH to between 6.5 and 7.5, and recycling the separated water to prepare the mixed alkali solution in step S1;

[0035] S6, dissolving oxalic acid in water to prepare an oxalic acid solution with a pH value between 5.5 and 6.0, and fully dissolving the solid obtained by washing in step S5 in the oxalic acid solution to obtain a suspension; wherein the mass ratio of the solid component to the oxalic acid solution is 1:3 to 1:6;

[0036] S7. Aging the suspension obtained in step S6 at room temperature for 24 to 48 hours to obtain a gel. The gel is frozen at -80°C to 20°C for 12 to 24 hours, dried in a freeze dryer for 5 to 12 hours, and finally crushed to obtain nano-aluminum silicate powder.

[0037] Example 1

[0038] Prepare a mixed alkali solution with a NaOH concentration of 4 mol / L and a Na2CO3 concentration of 1 mol / L;

[0039] The carbonated refined slag and the mixed alkali solution are mixed in a mass ratio of 1:10 to prepare a suspension;

[0040] The suspension was stirred at 80°C for 40 min.

[0041] The suspension was then filtered, and water glass (57% H2O, 10% Na2O, 33% SiO2) was added to the filtrate at a concentration of 15% of the filtrate's mass. The filtrate was then shaken at 70°C for 2 hours until a sol appeared in the filtrate.

[0042] The filtrate containing the sol is centrifuged and the sol obtained by centrifugation is fully washed to pH = 7.2;

[0043] The sol was then dispersed in an oxalic acid solution with a pH of 5.6, with a mass ratio of solid components to oxalic acid solution of 1:5;

[0044] The dispersed sol suspension was aged at room temperature for 24 hours to form a gel, and then the gel was frozen at -20°C for 12 hours. The frozen gel was then dried in a freeze dryer for 6 hours to obtain a powdered nano-aluminum silicate product.

[0045] like Figure 1 The following is a scanning electron microscope image of the nano-aluminum silicate prepared in this example. The primary particle size of the nano-aluminum silicate is about 20-60 nm. The BET specific surface area of the sample obtained by the N2 adsorption method is 103.56 m 2 / g.

[0046] Example 2

[0047] Prepare mixed alkali solution with NaOH concentration of 3 mol / L and Na2CO3 concentration of 1 mol / L;

[0048] The carbonated refined slag and the mixed alkali solution are mixed in a mass ratio of 1:5 to prepare a suspension;

[0049] The suspension was stirred at 70°C for 60 min.

[0050] The suspension was then filtered, and water glass (H2O 57%, Na2O 10%, SiO2 33%) was added to the filtrate in an amount of 20% of the filtrate mass. The filtrate was then shaken at 70°C for 1 hour until a sol appeared in the filtrate.

[0051] The filtrate containing the sol was centrifuged and the sol obtained by centrifugation was fully washed to pH = 7.2.

[0052] The sol was then dispersed in an oxalic acid solution with a pH of 5.6, with a mass ratio of solid components to oxalic acid solution of 1:3;

[0053] The dispersed sol suspension was aged at room temperature for 48 hours to form a gel, and then the gel was frozen at -80°C for 12 hours, and then the frozen gel was dried in a freeze dryer for 10 hours.

[0054] A powdery nano-aluminum silicate product is obtained.

[0055] like Figure 2 As shown in FIG, the scanning electron microscope image of the nano-aluminum silicate prepared in this embodiment shows that the particle size of the nano-aluminum silicate is relatively uniform, with a primary particle size of about 30 nm. Figure 3 As shown in Figure 2, the BET specific surface area of the sample obtained by N2 adsorption method is 97.26 m 2 / g, such as Figure 4 As shown, the whiteness measured by a whiteness meter is 94.7%.

[0056] The above is only an embodiment of the present invention, and common knowledge such as the specific technical solutions or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the description can be used to interpret the content of the claims.

Claims

1. A method for preparing nano-aluminum silicate by using mixed alkali and refined slag, characterized in that: The following steps are involved: S1, prepare NaOH and Na2CO3 mixed alkali solution; S2, mixing the carbonated refined slag and the mixed alkali solution obtained in step S1 at a mass ratio of 1:5 to 1:15 to prepare a suspension; S3, stirring the suspension obtained in step S2, filtering after stirring, and removing the filter residue to obtain a filtrate; S4, adding water glass to the filtrate obtained in step S3 and shaking to form a sol; S5, centrifuging the sol obtained in step S4; The separated solid components are fully washed to adjust their pH and remove impurities, and the separated water is recycled to prepare the mixed alkali solution in step S1; S6, dissolving oxalic acid in water to prepare an oxalic acid solution, and fully dissolving the solid obtained by washing in step S5 in the oxalic acid solution to obtain a suspension; wherein the mass ratio of the solid component to the oxalic acid solution is 1:3 to 1:6; S7. Aging the suspension obtained in step S6 to obtain a gel, and freezing, drying and crushing the gel to obtain nano-aluminum silicate powder.

2. The method for preparing nano-aluminum silicate by using mixed alkali and refined slag according to claim 1, characterized in that: In S1, the concentration of NaOH in the prepared mixed alkali solution is 2-4 mol / L; the concentration of Na2CO3 is 0.5-1.5 mol / L.

3. The method for preparing nano-aluminum silicate by using mixed alkali and refined slag according to claim 1, characterized in that: In S3, the suspension is stirred at a temperature of 40 to 80° C. for 40 to 60 minutes.

4. The method for preparing nano-aluminum silicate by using mixed alkali and refined slag according to claim 1, characterized in that: In S4, the composition of water glass by mass is: H2O accounts for 50-60%, Na2O accounts for 10-20%, and SiO2 accounts for 20-40%; the amount of water glass added is 15%-30% of the filtrate mass; the shaking conditions after adding water glass are: shaking at a temperature of 70-80°C for 1.5-2h.

5. The method for preparing nano-aluminum silicate by using mixed alkali and refined slag according to claim 1, characterized in that: In S5 , the separated solid component is washed and then adjusted to a pH value between 6.5 and 7.

5.

6. The method for preparing nano-aluminum silicate by using mixed alkali and refined slag according to claim 1, characterized in that: In S6, the pH value of the prepared oxalic acid solution is between 5.5 and 6.

0.

7. The method for preparing nano-aluminum silicate by using mixed alkali and refined slag according to claim 1, characterized in that: In S7, the conditions for aging the suspension to obtain the gel are: aging at room temperature for 24 to 48 hours; the conditions for freezing the gel are: freezing at -80°C to 20°C for 12 to 24 hours; and the conditions for drying are: drying in a freeze dryer for 5 to 12 hours.

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