Preparation method of solid waste-based calcium-silicon-aluminum system cementing material

Abstract

The application discloses a preparation method of a solid waste-based calcium-silicon-aluminum system cementing material, which comprises the following steps: adding a modifier into fly ash, steel slag and red mud, and then using calcium carbide slag slurry to stimulate the red mud, so that a synergistic effect is generated; and adding an industrial by-product trimethylchlorosilane to stimulate the hydrolysis and condensation of the trimethylchlorosilane under alkaline conditions, so that polysiloxane is formed, the added waste glass fiber is combined with the calcium silicate gel (C-S-H) system to form a more compact multidimensional structure, the strength of the calcium-silicon-aluminum system cementing material is further improved, and cracking is prevented. The preparation method uses multiple solid wastes and industrial by-products, raw materials are easy to obtain, the method is simple, the prepared material has excellent performance after maintenance, and has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solid waste-based gel materials, and particularly relates to a preparation method of a solid waste-based calcium-silicon-aluminum system gel material. BACKGROUND

[0002] Steel slag, fly ash and red mud are common solid waste materials, and with the popularization of resource utilization, more and more attention is paid. At present, there are many examples of solid waste utilization of steel slag, fly ash and red mud, especially steel slag and fly ash, which are of great concern due to their huge reserves. For example, as one of the three difficult-to-utilize solid wastes, red mud has formed a relatively systematic comprehensive utilization form in terms of source reduction, resource recovery and soil remediation, but the comprehensive utilization rate is only 7.6%, and further research and exploration of the resource utilization of red mud are still needed.

[0003] In terms of metallurgical comprehensive utilization, steel slag among the three types of waste slag is the most difficult to recycle, because steel slag is mainly used for concrete and roadbed admixture, and China has no basic standard for this product, and the quality is unstable compared with natural products, which leads to difficulty in market competition. The main technology for stabilizing steel slag at present is hot stewing and hot splashing process, but the effect of controlling its stability is not ideal. Steel slag grinding is a difficulty faced by all enterprises, which limits the comprehensive utilization of steel slag.

[0004] Red mud has strong alkalinity and contains elements such as iron, silicon and aluminum. Red mud is produced by Bayer process and sintering process, and red mud contains many minerals, which has a good effect on soil remediation. Red mud can adsorb heavy metal ions and improve water quality after mixing with water, and is a low-cost adsorbent. Red mud is harmless and environmentally friendly after desalting and desalting treatment, but its application is not large. Red mud has mature technology for flue gas treatment and building materials, which can maximize the resource utilization of red mud and minimize the impact on environmental pollution. Fly ash is widely used, but mainly in the building materials industry, and the utilization level is low, while fly ash can be used to produce silicon-aluminum alloy and aluminum oxide, but the cost and economic benefit are difficult. The fine and high value-added comprehensive utilization of fly ash should not be limited to the separation and extraction of high content of aluminum and silicon elements.

[0005] Scientific, reasonable and effective utilization of solid waste materials can not only bring good economic, environmental and social benefits, but also requires a lot of research and development work for true comprehensive utilization.

[0006] Therefore, it is necessary to propose a preparation method of a solid waste-based calcium-silicon-aluminum system gel material to solve the problem of resource utilization of multiple solid wastes. SUMMARY

[0007] In view of this, the purpose of the present application is to provide a preparation method of solid waste-based calcium-silicon-aluminum system cementing material, solving the problem of resource utilization of various solid wastes.

[0008] To solve the above problems, the present application scheme is as follows:

[0009] The first aspect of the present application is to provide a preparation method of solid waste-based calcium-silicon-aluminum system cementing material, comprising the following steps:

[0010] S1. Add a modifier, carbide slag slurry to the mixture of fly ash, steel slag and red mud, and mix and pulp;

[0011] S2. Add waste glass fiber and industrial by-product trimethylchlorosilane to the pulped material, and stir under sealed conditions for 1-3h to obtain a solid waste-based calcium-silicon-aluminum system cementing material;

[0012] The mass percentage of fly ash, steel slag and red mud in the mixture is 60-80%, 5-20% and 10-30% respectively; the modifier is desulfurization gypsum and Portland cement, and the total addition amount is 3-8wt%; the addition amount of carbide slag slurry is 50-80wt% of the mixture;

[0013] The addition amount of waste glass fiber and trimethylchlorosilane is 0.01-0.2% and 0.005-0.1% of the mass of the pulped material respectively.

[0014] Further, in step S1, the mass ratio of Portland cement to desulfurization gypsum in the modifier is (1.5-5):1.

[0015] Further, in step S1, the Portland cement is ordinary Portland cement.

[0016] Further, in step S1, the ratio of the sum of the mass fraction of steel slag and fly ash to the sum of the mass fraction of red mud and fly ash in the mixture is (0.8-1):1.

[0017] Further, in step S1, the water content of the carbide slag slurry is 40-60wt%.

[0018] Further, in step S2, the length of the waste glass fiber is 0.5-2mm, and it is cleaned before use

[0019] Further, the red mud is sintered at 650-750℃; preferably, the sintering temperature is 700℃.

[0020] The second aspect of the present application is to provide a solid waste-based calcium-silicon-aluminum system cementing material, which is prepared by the preparation method of the first aspect and cured.

[0021] Further, the curing time is more than 28 days.

[0022] A third aspect of the present application is to provide the application of the solid waste-based calcium-silicon-aluminum system cementing material in the building material.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] The preparation method of the solid waste-based calcium-silicon-aluminum system cementing material adds a modifier to the fly ash, steel slag and red mud, then uses the carbide slag slurry to excite the synergistic effect, adds the industrial by-product trimethylchlorosilane, and can excite the trimethylchlorosilane hydrolysis and release a large amount of heat under alkaline conditions, and then condenses to form polysiloxane, so that the waste glass fiber added cooperates with the calcium silicate gel (C-S-H) system to form a more compact multi-dimensional structure, further improving the strength of the calcium-silicon-aluminum system cementing material and preventing cracking. The preparation method uses a variety of solid wastes and industrial by-products, and the raw materials are easy to obtain and the method is simple. The prepared material has excellent performance after curing and has a wide application prospect. DETAILED DESCRIPTION

[0025] The following examples are used to illustrate the present application, but do not limit the scope of the present application. Modifications or replacements of the methods, steps or conditions of the present application without departing from the spirit and essence of the present application all belong to the scope of the present application.

[0026] The reagents used in the following examples are common reagents in the art, and are commercially available standard products if not otherwise specified. If not otherwise specified, the experimental methods used are known methods in the art.

[0027] The steel slag used in the examples is purchased from Henan Zhengzhou Gongyi Longze Water Purification Material Co., Ltd., the fly ash is from Henan Zhengzhou Gongyi Longze Water Purification Material Co., Ltd., which is a first-class fly ash, and the red mud is purchased from Shandong Yizhuo Material Co., Ltd. The water content of the carbide slag slurry is 40-60wt%, and the calcium hydroxide content in the carbide slag slurry is 20-35wt%. Trimethylchlorosilane is a common by-product formed during the industrial preparation of silane. The waste glass fiber is a chopped glass fiber with a length of 0.5-2mm.

[0028] Example 1

[0029] The preparation method of the solid waste-based calcium-silicon-aluminum system cementing material has the following steps:

[0030] 1. The red mud is sintered at a temperature of 700℃, and then crushed to obtain a red mud with volcanic ash activity;

[0031] 2. Take the mixture of fly ash, steel slag and step 1 sintered and crushed red mud, add desulfurization gypsum and ordinary Portland cement PO•42.5 for mixing and stirring, the mass percentage of fly ash, steel slag and red mud in the mixture is 60%, 20% and 20% respectively; the addition amount of desulfurization gypsum and Portland cement PO•42.5 is 1wt% and 5wt% of the mixture respectively; then add carbide slag slurry, the addition amount is 60wt% of the mixture, mix and high-speed stir to make slurry;

[0032] 3. Take the slurry after mixing and stirring in step 2, add 0.05% of waste glass fiber and 0.05% of trimethylchlorosilane, seal and stir for 3h to obtain solid waste-based calcium-silicon-aluminum system cementing material;

[0033] 4. Take the appropriate amount of material obtained in step 3, pour it into a 40mm×40mm×160mm triple mold, shake it evenly, attach a plastic wrap and let it stand, demold after 1d, then put the sample into a standard curing box with temperature of (20±1)℃ and humidity ≥95% for curing until the specified age for sampling and analysis.

[0034] Example 2

[0035] The preparation method of the solid waste-based calcium-silicon-aluminum system cementing material comprises the following steps:

[0036] 1. Sinter the red mud at a temperature of 750℃, and then crush it to obtain red mud with pozzolanic activity;

[0037] 2. Take the mixture of fly ash, steel slag and step 1 sintered and crushed red mud, add desulfurization gypsum and ordinary Portland cement PO•42.5 for mixing and stirring, the mass percentage of fly ash, steel slag and red mud in the mixture is 70%, 15% and 15% respectively; the addition amount of desulfurization gypsum and Portland cement PO•42.5 is 1wt% and 5wt% of the mixture respectively; then add carbide slag slurry, the addition amount is 70wt% of the mixture, mix and high-speed stir to make slurry;

[0038] 3. Take the slurry after mixing and stirring in step 2, add 0.08% of waste glass fiber and 0.03% of trimethylchlorosilane, seal and stir for 2h to obtain solid waste-based calcium-silicon-aluminum system cementing material;

[0039] 4. Take the appropriate amount of material obtained in step 3, pour it into a 40mm×40mm×160mm triple mold, shake it evenly, attach a plastic wrap and let it stand, demold after 1d, then put the sample into a standard curing box with temperature of (20±1)℃ and humidity ≥95% for curing until the specified age for sampling and analysis.

[0040] Example 3

[0041] The preparation method of the solid waste-based calcium-silicon-aluminum system cementing material comprises the following steps:

[0042] 1. After sintering at a temperature of 700 DEG C, the red mud is crushed to obtain red mud with volcanic ash activity;

[0043] 2. The mixture of fly ash, steel slag and the sintered and crushed red mud in step 1 is mixed and stirred by adding desulfurization gypsum and ordinary Portland cement PO•42.5, wherein the mass percentage of fly ash, steel slag and red mud in the mixture is 70%, 10% and 20% respectively, the addition amount of desulfurization gypsum and Portland cement PO•42.5 is 1 wt% and 5 wt% of the mixture respectively, and then the addition amount of carbide slag slurry is 80 wt% of the mixture, and the mixture is stirred at high speed after mixing;

[0044] 3. The mixture obtained in step 2 is mixed and stirred by adding 0.03% of waste glass fiber and 0.08% of trimethylchlorosilane, and the mixture is stirred for 2 hours under sealed condition to obtain the solid waste-based calcium-silicon-aluminum system cementing material;

[0045] 4. The mixture obtained in step 3 is poured into a triple mold with a size of 40mm*40mm*160mm, and the mixture is evenly vibrated and placed under a plastic wrap, and then the mixture is demolded after 1 day, and then the sample is placed in a standard curing box with a temperature of (20±1) DEG C and a humidity of ≥95% for curing until the sample is taken out for analysis at a specified age.

[0046] Comparative example 1

[0047] The preparation method of the solid waste-based calcium-silicon-aluminum system cementing material is the same as that in example 1, except that the red mud is not sintered.

[0048] Comparative example 2

[0049] The preparation method of the solid waste-based calcium-silicon-aluminum system cementing material is the same as that in example 1, except that the sintering temperature of the red mud in step 1 is 800 DEG C.

[0050] Comparative example 3

[0051] The preparation method of the solid waste-based calcium-silicon-aluminum system cementing material is the same as that in example 1, except that the carbide slag slurry in step 2 is replaced by sodium hydroxide solution with the same concentration.

[0052] Comparative example 4

[0053] The preparation method of the solid waste-based calcium-silicon-aluminum system cementing material is the same as that in example 1, except that the addition amount of desulfurization gypsum and Portland cement PO•42.5 in step 2 is 3 wt% and 3 wt% respectively.

[0054] Comparative example 5

[0055] The preparation method of the solid waste-based calcium-silicon-aluminum system cementitious material is the same as that of Example 1, except that no waste glass fiber is added in step 3.

[0056] Comparative Example 6

[0057] The preparation method of the solid waste-based calcium-silicon-aluminum system cementitious material is the same as that of Example 1, except that no industrial by-product trimethylchlorosilane is added in step 3.

[0058] Test Example

[0059] The compressive strength of the cementitious material is characterized by the compressive strength of the test block. When the test block is cured to the age, the test block is taken out of the curing box, and the compressive strength of the test block is tested. The compressive strength calculation formula is as follows:

[0060]

[0061] R S The compressive strength of the test block is MPa, F S The maximum load of the test block is kN, A S The force area of the test block is m 2 .

[0062] Test steps: place the standard cured test block (40 mm x 40 mm x 160 mm) in the compression and bending integrated machine at a loading speed of 2.4 kN / s to pressurize until the test block is damaged, and record the maximum loading pressure. The compressive strength of the sample is calculated using the formula.

[0063] Table 1:

[0064]

[0065] The initial setting and final setting time is determined according to GB / T 1346-2001 “Cement Standard Consistency Water Content, Setting Time, and Stability Test Method”. The results are shown in Table 2.

[0066] Table 2: Comparison of initial setting and final setting time

[0067]

[0068] From Table 1, it is not difficult to see that the strength of the gel material after hydration of Examples 1-3 can reach 25 MPa at 28 days, while the use of unsintered red mud in Comparative Example 1 leads to a significant decrease in compressive strength, and in Comparative Example 2, the sintering temperature reaches 800°C, and the strength decreases slightly; in Comparative Example 3, the use of ordinary lye for excitation also affects the compressive strength, and the decrease in compressive strength in Comparative Example 4 indicates that the addition ratio of desulfurization gypsum and Portland cement PO•42.5 also affects the compressive strength. The use of no waste glass fiber in Comparative Example 5 and no trimethylchlorosilane in Comparative Example 6 will cause a significant decrease in compressive strength, indicating that glass fiber and trimethylchlorosilane play an important role in improving compressive strength.

[0069] In Table 2, the initial setting time of Examples 1-3 is maintained at about 50 min, and the final setting time is slightly greater than 100 min, which is significantly shorter than that of PO•42.5 cement, and has a significant advantage; at the same time, the setting time of Comparative Examples 1-4 is prolonged. The possible reason is that in Comparative Example 1, Al2O3 exists in crystalline state in red mud, and the unsintering leads to poor hydration reaction activity, while in Comparative Example 2, the sintering temperature is too high, which leads to the generation of Ca2Al2SiO7, NaAlSiO4 and other crystalline phase materials, resulting in a hydration reaction rate lower than that of the previous (non-crystalline phase) Al2O3, thereby showing a decrease in strength, and the crystalline state is more difficult to hydrate. When sodium hydroxide is used as a hydration activator in Comparative Example 3, the hydration activity is relatively low due to the lack of supplemental calcium, and the compressive strength is affected. The increase in the ratio of desulfurization gypsum and cement leads to an excess of desulfurization gypsum content, and other raw materials do not have the activity of cement, so the hydration reaction will be slow. The use of no waste glass fiber in Comparative Example 5 has little effect on the setting time, but the use of no trimethylchlorosilane in Comparative Example 6 leads to a significant increase in the setting time. The possible reason is that the addition of trimethylchlorosilane produces hydrolysis and polycondensation under alkaline conditions, thereby rapidly increasing the viscosity of the system, and forming a more compact multi-dimensional structure by combining the calcium silicate gel (C-S-H) system and glass fiber.

[0070] The above examples show that the content of calcium-silicon-aluminum oxides in sintered red mud increases, and the hydration activity is enhanced. Calcium hydroxide exists in large amounts in the calcium carbide slag slurry, which provides an alkaline environment and supplements calcium, further promotes the generation of gel products with silicon-aluminum active materials, most of which are C-S-H, C-A-S-H and tobermorite and other hydration products. Compared with steel slag, cement as an auxiliary additive improves the early strength and provides more C2S and C3S to participate in the hydration reaction, and desulfurization gypsum mainly has a synergistic effect with cement to provide tobermorite as a gel product for early hydration reaction. The preparation method provided by the present application uses a variety of solid wastes, and the method is simple, the setting time of the prepared material is excellent, and the performance after curing is excellent, and has a wide application prospect.

[0071] The application is not limited only to the described in the specification and embodiments, and therefore for those skilled in the art can easily realize additional advantages and improvements, and therefore the application is not limited to specific details, representative solutions and described embodiments without departing from the spirit and scope of the general concept defined by the claims and their equivalents.

Claims

1. A method for preparing a solid waste-based calcium-silico-aluminate system cementitious material, characterized in that, The steps comprise: S1. Adding a modifier, carbide slag slurry to the mixture of fly ash, steel slag and red mud, mixing and beating; S2. Adding waste glass fiber and industrial by-product trimethylchlorosilane to the beaten material, stirring under sealed condition for 1-3h to obtain solid waste-based calcium-silicon-aluminum system cementing material; The mass percentage of fly ash, steel slag and red mud in the mixture is 60-80%, 5-20% and 10-30% respectively; The modifier is desulfurization gypsum and Portland cement, and the total addition amount is 3-8wt%; The addition amount of carbide slag slurry is 50-80wt% of the mixture; The addition amount of waste glass fiber and trimethylchlorosilane is 0.01-0.2% and 0.005-0.1% of the mass of the beaten material respectively.

2. The production method according to claim 1, characterized by, In step S1, the mass ratio of Portland cement to desulfurization gypsum in the modifier is (1.5-5):

1.

3. The preparation method according to claim 1, characterized in that, In step S1, the ratio of the sum of the mass fraction of steel slag and fly ash to the sum of the mass fraction of red mud and fly ash in the mixture is (0.8-1):

1.

4. The production method according to claim 1, characterized by, In step S1, the water content of the carbide slag slurry is 40-60wt%.

5. The preparation method according to claim 1, characterized in that, In step S1, the red mud is sintered at 650-750℃.

6. The production method according to claim 5, wherein The sintering temperature is 700℃.

7. The preparation method according to claim 1, characterized in that, In step S2, the length of the waste glass fiber is 0.5-2mm, and it is cleaned before use.

8. A solid waste-based calcium-silico-aluminate system cementitious material characterized in that, Obtained by the preparation method of any one of claims 1-7.

9. The solid waste-based calcium-silico-aluminum system cementitious material of claim 8, wherein, The curing time is more than 28 days.

10. The solid waste-based calcium-silicon-aluminum system cementing material of claim 8 or 9 for use in building materials.

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