Low-carbon cementitious material and preparation method thereof

Abstract

The application discloses a low-carbon cementing material and a preparation method thereof. The low-carbon cementing material is prepared by the following steps: taking 100 parts of modified saponification residue and 80-95 parts of modified silica pressure filtration sludge, adding 2-5 parts of gypsum and 0.2-0.5 parts of grinding aid, and then grinding for 20-40 minutes, and then adding 5-12 parts of nano-aluminum silicate sol and continuing to grind for 10-20 minutes. The application is based on the complementary conditions of calcium-silicon materials of saponification residue and silica pressure filtration sludge, and realizes a method for preparing the low-carbon cementing material by modifying the two kinds of solid wastes and reasonably using multiple functional components, and realizes the resource utilization of the two kinds of solid wastes.

Description

Technical Field

[0001] This invention belongs to the field of industrial solid waste treatment technology, specifically, it relates to a method for preparing low-carbon cementitious materials using saponification residue and nano-silica filter press sludge. Technical Background

[0002] Most existing solid waste is a mixture of calcium, silicon, or aluminum oxides; and the main components of cementitious materials used in building materials are also mainly calcium, silicon, and aluminum oxides. Therefore, combining different solid wastes to prepare building cementitious materials is an important way to realize their resource utilization. The calcium-to-silicon ratio in cementitious materials and the activity of their raw materials are the main factors affecting their performance.

[0003] The filter press sludge produced from the production of nano-silica and the saponification residue from the production of chlorohydrin-based propylene oxide are respectively siliceous and calcareous solid wastes. In the silica production sector, water consumption is high. To address wastewater issues, reduce production costs, and recycle water resources, extensive purification processes have been implemented. During purification, a large amount of solids in the wastewater is filtered out, resulting in filter press sludge. Filter press sludge is primarily composed of siliceous materials with high salt content and is produced in large quantities. Its harmless treatment and large-scale comprehensive utilization have always been technical challenges for domestic and international manufacturers. Currently, the high salt content in filter press sludge is mainly addressed through washing, but washing requires large amounts of water and primarily employs processes such as evaporation and crystallization. This indirectly leads to high production costs and low cost-effectiveness for nano-silica, as well as high investment costs, reducing the competitiveness of the main product, silica. Therefore, how to achieve low-cost resource utilization and large-scale utilization of silica filter press sludge is a key research and application challenge. Currently, there is no research in this area.

[0004] Saponification slag is an industrial waste residue emitted during the chlorohydrin process of propylene oxide production. Its main component is calcareous material, which is mostly piled up in the open, causing problems such as land occupation and dust. It not only threatens the environment, but has also become a key factor restricting the sustainable development of the factory. There is an urgent need for comprehensive utilization technology of saponification slag. Through reasonable utilization methods, saponification slag can be turned into a valuable resource, solving the problem of saponification slag accumulation and generating certain economic and social benefits.

[0005] Based on the above analysis, a good calcium-to-silicon ratio can be achieved by blending filter press sludge from silica production and saponification residue from chlorohydrin propylene oxide production in a certain proportion, suggesting the feasibility of its application as a cementitious material. However, there is currently no research on this aspect. Summary of the Invention

[0006] To address the problems existing in the background technology, this invention is based on the complementary conditions of calcium-silicon materials in the production of filter press sludge and saponification residue from silica. By modifying the two solid wastes, and through the combination of the two, a method for preparing low-carbon cementitious materials using saponification residue and nano-silica filter press sludge is realized, thereby achieving the resource utilization of these two solid wastes.

[0007] To achieve the above objectives, the specific technical solution of the present invention is as follows:

[0008] A low-carbon cementitious material, comprising the following components in parts by mass:

[0009]

[0010] The modified saponification residue is obtained by adding the saponification residue to a mixed aqueous solution of nano-calcium silicate, triethanolamine, and polycarboxylate superplasticizer (PCE), and then passing carbon dioxide gas through it, followed by ball milling and drying.

[0011] The modified silica filter press sludge is obtained by mixing silica filter press sludge with dilute hydrochloric acid, drying it, and then wet ball milling it with triethanolamine and sodium hydroxide solution.

[0012] The specific preparation method of the modified saponification residue includes: adding the saponification residue to a mixed aqueous solution of nano-calcium silicate, triethanolamine, and polycarboxylate superplasticizer (PCE), wet ball milling for 5-10 min, continuously introducing carbon dioxide gas into the grinding equipment, continuing ball milling for 10-20 min, stopping the introduction of carbon dioxide gas, continuing ball milling for 5-10 min, and drying to obtain the residue; nano-calcium silicate promotes the formation of micro-nano particles in the saponification residue, while triethanolamine and PCE prevent the agglomeration of the formed nano-calcium silicate;

[0013] The saponification residue has a mass fraction of 100 parts, and the mixed aqueous solution of nano-calcium silicate, triethanolamine, and polycarboxylate superplasticizer (PCE) has a mass fraction of 10 to 15 parts, which is consistent with the mass fraction of each component in the above-mentioned low-carbon cementitious material.

[0014] The mixed aqueous solution of nano-calcium silicate, triethanolamine, and polycarboxylate superplasticizer (PCE) is a suspension formed by mixing nano-calcium silicate, triethanolamine, polycarboxylate superplasticizer (PCE) and water in a mass ratio of 10:2-4:4-6:15-20 and then dispersing the mixture by ultrasonication.

[0015] The method for preparing the modified silica filter press sludge includes: mixing the silica filter press sludge with dilute hydrochloric acid until uniform, allowing it to stand under sealed conditions for 4-8 hours, drying it, and then mixing it with triethanolamine and sodium hydroxide solution, followed by wet ball milling for 5-10 minutes, and drying it at 60-80℃. The surface is activated by dilute hydrochloric acid, the dispersibility between filter press sludge particles is improved by triethanolamine, and the alkaline activation by sodium hydroxide solution promotes the formation of active silica and micro-particle sodium silicate. Drying at 60-80℃ further promotes the activation of the mixture under these conditions.

[0016] The silica filter press sludge comprises 100 parts by mass, dilute hydrochloric acid comprises 5-10 parts by mass, triethanolamine comprises 1-2 parts by mass, and sodium hydroxide solution comprises 20-30 parts by mass, the mass percentages of which are consistent with the mass percentages of each component in the aforementioned low-carbon cementitious material.

[0017] Furthermore, the mass fraction of the dilute hydrochloric acid is 9-15%.

[0018] Furthermore, the sodium hydroxide solution has a mass fraction of 20-40%.

[0019] The present invention also provides a method for preparing the above-mentioned low-carbon cementitious material, specifically comprising: mixing modified saponification residue, modified silica filter sludge, gypsum and grinding aid in proportion, grinding for 20-30 minutes, adding nano-alumina silica sol, and continuing to grind for 5-10 minutes to obtain the material.

[0020] The present invention has the following beneficial effects:

[0021] (1) This invention proposes a method for producing filter press sludge and saponification residue using modified nano silica, thereby realizing the resource utilization and large-scale application of filter press sludge and saponification residue produced by nano silica.

[0022] (2) This invention realizes the synergistic compounding effect of two solid wastes and prepares a low-carbon cementitious material that can replace part of the cement and achieve good results;

[0023] (5) The innovative use of nano-alumina silicate sol in the preparation process can significantly improve the surface smoothness and morphology of low-cementing material particles and promote the activation of low-cementing material particle activity; the use of cementing materials in concrete can significantly improve the performance and mechanical properties of concrete mixtures. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to embodiments:

[0025] Example 1

[0026] A low-carbon cementitious material based on saponification residue and silica filter press sludge, comprising the following components by mass parts:

[0027]

[0028] The modified saponification residue is prepared by adding 100 parts of saponification residue to 15 parts of a mixed solution of nano-calcium silicate, triethanolamine, and PCE, wet ball milling for 5 minutes, continuously introducing carbon dioxide gas into the grinding equipment, continuing ball milling for 20 minutes, stopping the introduction of carbon dioxide gas, continuing ball milling for 5 minutes, and then drying to obtain the residue; the mixed solution of nano-calcium silicate, triethanolamine, and PCE is a suspension formed by mixing nano-calcium silicate, triethanolamine, PCE, and water in a mass ratio of 10:4:4:20 and then dispersing it ultrasonically.

[0029] The modified silica filter press sludge is prepared by mixing 100 parts of filter press sludge with 10 parts of dilute hydrochloric acid, letting it stand for 4 hours under sealed conditions, drying it, and then mixing it with 2 parts of triethanolamine and 20 parts of sodium hydroxide solution. The mixture is then wet-milled for 10 minutes and dried at 60°C. The mass fraction of the dilute hydrochloric acid is 9%, and the mass fraction of the sodium hydroxide solution is 40%.

[0030] The preparation method of the low-carbon cementitious material is as follows:

[0031] After mixing the modified saponification residue, modified silica filter sludge, gypsum and grinding aid in a certain proportion, and grinding for 20 minutes, 12 parts of nano-alumina silicate sol were added, and grinding was continued for 5 minutes to obtain the final product.

[0032] Example 2

[0033] A low-carbon cementitious material based on saponification residue and silica filter press sludge, comprising the following components by mass parts:

[0034]

[0035] The modified saponification residue is prepared by adding 100 parts of saponification residue to 10 parts of a mixed solution of nano-calcium silicate, triethanolamine, and PCE, wet ball milling for 10 minutes, continuously introducing carbon dioxide gas into the grinding equipment, continuing ball milling for another 10 minutes, stopping the introduction of carbon dioxide gas, continuing ball milling for another 10 minutes, and then drying to obtain the residue; the mixed solution of nano-calcium silicate, triethanolamine, and PCE is a suspension formed by mixing nano-calcium silicate, triethanolamine, PCE, and water in a mass ratio of 10:2:6:15 and then dispersing it by ultrasonication.

[0036] The modified silica filter press sludge is prepared by mixing 100 parts of filter press sludge with 5 parts of dilute hydrochloric acid, letting it stand for 8 hours, drying it, and then mixing it with 1 part of triethanolamine and 30 parts of sodium hydroxide solution. The mixture is then wet-milled for 5 minutes and dried at 80°C. The mass fraction of the dilute hydrochloric acid is 15%, and the mass fraction of the sodium hydroxide solution is 30%.

[0037] The preparation method of the low-carbon cementitious material is as follows:

[0038] After mixing the modified saponification residue, modified silica filter sludge, gypsum and grinding aid in a certain proportion, and grinding for 30 minutes, 5 parts of nano-alumina silicate sol were added, and grinding was continued for 10 minutes to obtain the final product.

[0039] Example 3

[0040] A low-carbon cementitious material based on saponification residue and silica filter press sludge, comprising the following components by mass parts:

[0041]

[0042] The modified saponification residue is prepared by adding 100 parts of saponification residue to 12 parts of a mixed solution of nano-calcium silicate, triethanolamine, and PCE, wet ball milling for 8 minutes, continuously introducing carbon dioxide gas into the grinding equipment, continuing ball milling for 12 minutes, stopping the introduction of carbon dioxide gas, continuing ball milling for 8 minutes, and drying to obtain the residue; the mixed solution of nano-calcium silicate, triethanolamine, and PCE is a suspension formed by mixing nano-calcium silicate, triethanolamine, PCE, and water in a mass ratio of 10:3:5:18 and then dispersing it by ultrasonication.

[0043] The modified silica filter press sludge is prepared by mixing 100 parts of filter press sludge with 5-10 parts of dilute hydrochloric acid, letting it stand for 6 hours, drying it, and then mixing it with 1.5 parts of triethanolamine and 25 parts of sodium hydroxide solution. The mixture is then wet-milled for 8 minutes and dried at 70°C. The mass fraction of the dilute hydrochloric acid is 12%, and the mass fraction of the sodium hydroxide solution is 20%.

[0044] The preparation method of the low-carbon cementitious material is as follows:

[0045] After mixing the modified saponification residue, modified silica filter sludge, gypsum and grinding aid in a certain proportion, and grinding for 25 minutes, 10 parts of nano-alumina silicate sol were added, and grinding was continued for 8 minutes to obtain the final product.

[0046] Comparative Example 1

[0047] The difference from Example 3 is that no nano-alumina silicate sol was added, and the powder was directly ground for 33 minutes.

[0048] Comparative Example 2

[0049] The difference from Example 3 is that 3 parts of nano-alumina silicate sol were incorporated.

[0050] Comparative Example 3

[0051] The difference from Example 3 is that 15 parts of nano-alumina silicate sol were incorporated.

[0052] Comparative Example 4

[0053] The difference from Example 3 is that the saponification residue was not modified.

[0054] Comparative Example 5

[0055] The difference from Example 3 is that the silica-produced filter press sludge was not modified.

[0056] Comparative Example 6

[0057] The difference from Example 3 is that the saponification residue and silica produced from the filter press sludge were not modified, and nano-alumina silicate sol was not added during mixing.

[0058] Comparative Example 7

[0059] The difference from Example 3 is that the saponification residue and silica produced from the filter press sludge were not modified, and nano-alumina silicate sol was incorporated during mixing.

[0060] Comparative Example 8

[0061] The difference from Example 3 is that no nano-calcium silicate was added during the modification of the saponification residue.

[0062] Comparative Example 9

[0063] The difference from Example 3 is that carbon dioxide was not introduced during the modification of the saponification residue.

[0064] Comparative Example 10

[0065] The difference from Example 3 is that carbon dioxide was introduced and ball milled for 20 minutes during the modification of the saponification residue.

[0066] The activity of the low-cementing material in each embodiment was compared according to the method of the 28-day compressive strength ratio test of cement mortar in GB / T12957-2005. The admixture amount was in accordance with the provisions of standard GB / T12957-2005. The low-cementing material and dihydrate gypsum were mixed evenly at a mass ratio of 90:10, and the total admixture amount was 30% of the cement mass.

[0067] The experiment used Shanshui 42.5 ordinary Portland cement, produced by Shandong Cement Plant. According to the relevant provisions of GB / T12957-2005, the 28-day compressive strength and activity index of each group of samples were tested, as shown in Table 1.

[0068] Table 1. Compressive strength and activity index of each group of samples at 28 days.

[0069]

[0070] As shown in Table 1, the activity index of the low-cementing material in the examples reached 113%, far exceeding the standard value and the comparative examples. Comparing Example 3 and Comparative Examples 1-3, it can be seen that neither the absence of nano-alumina silicate sol nor the excessive addition of nano-alumina silicate sol leads to a decrease in the activity index of the low-cementing material. This is mainly because the added nano-alumina silicate sol can significantly improve the surface smoothness and morphology of the particles, promoting activity activation. When no sol or a small amount is added, the modified saponification slag has low activity; when an excessive amount is added, the sol affects the dispersion and hydration reaction of the particles, causing a decrease in its activity index. Comparing Example 3 and Comparative Examples 4-6, it can be seen that when the saponification slag is not modified, or the filter press sludge is not modified, or neither is modified, the activity of the low-cementing material decreases significantly, especially when neither is modified, the activity decreases to 44%. Comparing Example 3 and Comparative Examples 7-8, it can be seen that when nano-calcium silicate and carbon dioxide are not added during the modification of saponification slag, the activity will also decrease. As can be seen from Comparative Example 9, when saponification slag is modified by excessive carbon dioxide, the activity will also decrease. This is mainly because when carbon dioxide is excessive, it reacts with the large amount of calcium oxide in the saponification slag to generate calcium carbonate, which cannot participate in the cement hydration reaction. Moreover, since the generated calcium carbonate is micro-nano-sized, it increases the water demand and viscosity of the mortar, making its workability worse, thus showing a decrease in activity.

Claims

1. A low-carbon cementitious material, characterized in that, The components, by mass parts, include the following: 100 parts of modified saponification residue, 80-95 parts of modified silica filter press sludge, 2-5 parts plaster Grinding aid 0.2~0.5 parts, 5-12 parts of nano-aluminosilicate sol; The modified saponification residue is obtained by adding the saponification residue to a mixed aqueous solution of nano-calcium silicate, triethanolamine, and polycarboxylate superplasticizer, passing carbon dioxide gas through it, ball milling, and then drying. The modified silica filter press sludge is obtained by mixing silica filter press sludge with dilute hydrochloric acid, drying it, and then wet ball milling it with triethanolamine and sodium hydroxide solution, followed by drying.

2. The low-carbon cementitious material according to claim 1, characterized in that, The modified saponification residue used in the modified saponification residue has a mass fraction of 100 parts, and the mass fraction of the mixed aqueous solution of nano-calcium silicate, triethanolamine, and polycarboxylate superplasticizer is 10-15 parts. The mass fraction basis is consistent with the mass fraction basis of each component in the above-mentioned low-carbon cementitious material. The mixed aqueous solution of nano-calcium silicate, triethanolamine, and polycarboxylate superplasticizer is a suspension formed by mixing nano-calcium silicate, triethanolamine, polycarboxylate superplasticizer, and water in a mass ratio of 10:2~4:4~6:15~20 and then dispersing the mixture using ultrasound.

3. The low-carbon cementitious material according to claim 1, characterized in that, The modified silica filter press sludge used comprises 100 parts by mass of silica filter press sludge, 5-10 parts by mass of dilute hydrochloric acid, 1-2 parts by mass of triethanolamine, and 20-30 parts by mass of sodium hydroxide solution. The mass percentages are consistent with those of the components in the aforementioned low-carbon cementitious material.

4. The low-carbon cementitious material according to claim 1, characterized in that, The mass fraction of the dilute hydrochloric acid is 9-15%; The sodium hydroxide solution has a mass fraction of 20-40%.

5. A low-carbon cementitious material according to any one of claims 1 to 4, characterized in that, The specific preparation method of the modified saponification residue includes: adding the saponification residue into a mixed aqueous solution of nano-calcium silicate, triethanolamine, and polycarboxylate superplasticizer, wet ball milling for 5-10 minutes, continuously introducing carbon dioxide gas into the grinding equipment, continuing ball milling for 10-20 minutes, stopping the introduction of carbon dioxide gas, continuing ball milling for 5-10 minutes, and drying to obtain the residue.

6. A low-carbon cementitious material according to any one of claims 1 to 4, characterized in that, The method for preparing the modified silica filter press sludge includes: stirring the silica filter press sludge with dilute hydrochloric acid until uniform, letting it stand for 4-8 hours under sealed conditions, drying it, and then mixing it with triethanolamine and sodium hydroxide solution, continuing wet ball milling for 5-10 minutes, and drying it at 60-80℃.

7. A method for preparing the low-carbon cementitious material according to any one of claims 1 to 6, characterized in that, Specifically, it includes: After mixing the modified saponification residue, modified silica filter sludge, gypsum and grinding aid in a certain proportion, grind for 20-30 minutes, add nano-alumina silicate sol, and continue grinding for 5-10 minutes to obtain the final product.

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