Silicone residue and magnesium residue composite reinforced recycled aggregate and preparation method thereof

Abstract

The application belongs to the field of comprehensive recycling of solid waste, and particularly relates to a kind of organic silicon slag and magnesium slag composite reinforced recycled aggregate and a preparation method thereof.The preparation method comprises the following steps: S1: organic silicon slag, water and alcohol amine grinding aid are mixed and wet ground to obtain organic silicon slag slurry; S2: magnesium slag and alcohol amine grinding aid are mixed and dry ground to obtain magnesium slag powder; S3: the magnesium slag powder, organic silicon slag slurry and water are uniformly mixed to obtain a suspension; S4: the recycled aggregate is soaked in water, ultrasonic cleaning is performed to remove surface impurities, then the recycled aggregate is taken out and soaked in the suspension obtained in step S3, stirring is performed at 100-300 r / h for 24-48 h, and after soaking is completed, natural drying is performed, thereby obtaining a kind of organic silicon slag and magnesium slag composite reinforced recycled aggregate.The application realizes comprehensive application of three kinds of solid waste, reduces environmental pollution caused by solid waste to land, air and the like, provides a technical path for enhancing recycled aggregate, and has good economic and social benefits.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of comprehensive recycling of solid waste, and particularly relates to a kind of organic silicon slag and magnesium slag composite reinforced recycled aggregate and a preparation method thereof. BACKGROUND

[0002] Organochlorosilane monomer and its derivative products such as organosilicon materials are more and more applied in various production links in modern industry due to their excellent insulation, waterproof, high temperature resistance and other properties. The global organosilicon production is rising, and China, as a large producer of organosilicon, accounts for about 67% of the global production capacity. According to statistics, the annual output of organosilicon in China is about 5 million tons, and about 50,000 tons of waste slurry is also generated annually. After hydrolysis and other treatment processes, the organosilicon and precious metals in the waste slurry are recovered, and the main component of the remaining organic silicon slag is silicon powder with large specific surface area and small average particle size, and the rest is a small amount of organosilicon and metal. On the other hand, China is also the largest producer of magnesium in the world, and the main smelting process is the Pidgeon process. Using this method to smelt magnesium will produce a large amount of magnesium slag. On average, 6 tons of magnesium slag will be discharged for every ton of crude magnesium produced. If it cannot be properly treated, it will not only pollute the environment, but also waste resources.

[0003] Construction waste solid waste is often used to produce recycled aggregate, but due to its main components such as concrete and sintered bricks, the surface of the recycled aggregate is rough, has many corners, and the microstructure is mostly loose and porous, which greatly limits its application range in recycled concrete. To solve this problem, researchers have developed various methods to enhance recycled aggregate, which can be roughly divided into physical enhancement, chemical modification, composite enhancement, etc., and have achieved many research results. However, there is no related report on the technical route of composite enhancement of recycled aggregate using the characteristics of organic silicon slag and magnesium slag. The present application provides a kind of organic silicon slag and magnesium slag composite reinforced recycled aggregate and a preparation method thereof, which has good ecological value and economic benefit. SUMMARY

[0004] In view of the problems and deficiencies of the prior art, the present application provides a kind of organic silicon slag and magnesium slag composite reinforced recycled aggregate and a preparation method thereof.

[0005] Based on the above purpose, the present application adopts the following technical scheme:

[0006] In the first aspect, the present application provides a preparation method of a kind of organic silicon slag and magnesium slag composite reinforced recycled aggregate, comprising the following steps:

[0007] S1: organic silicon slag, water and alcohol amine grinding aid are mixed and wet ground to obtain organic silicon slag slurry;

[0008] S2: Dry-grinding the magnesium slag and the alcoholamine grinding aid to obtain magnesium slag fine powder;

[0009] S3: Mixing magnesium slag powder, organosilicon slag slurry and water to obtain a suspension;

[0010] S4: soaking the recycled aggregate in water, ultrasonically cleaning to remove surface impurities, then taking it out and soaking it in the suspension obtained in step S3, stirring at 100-300 r / h for 24-48 hours, and drying it naturally after soaking to obtain a composite reinforced recycled aggregate of organic silicon slag and magnesium slag.

[0011] Preferably, the alcoholamine grinding aid is at least one of triethanolamine, triisopropanolamine, and diethanol monoisopropanolamine.

[0012] Preferably, the water is deionized water.

[0013] Preferably, the weight ratio of water to organosilicon slag in step S1 is (0.45-0.60):1, and the amount of alcoholamine grinding aid used is 0.5%-1.0% of the mass of the organosilicon slag.

[0014] Preferably, the amount of the alcoholamine grinding aid in step S2 is 0.5% to 2% of the mass of the magnesium slag.

[0015] Preferably, the weight ratio of the magnesium slag powder, organosilicon slag slurry and water in step S3 is 1:(3-5):(60-80).

[0016] Preferably, the mass fraction of silicon dioxide in the organosilicon slag in step S1 is not less than 99%.

[0017] Preferably, the magnesium slag in step S2 is granular reducing slag produced by the Pidgeon process for magnesium smelting.

[0018] Preferably, the wet grinding time in step S1 is 1 to 2 hours, and the wet grinding is performed until the average particle size of the organosilicon slag is 50 to 100 nm. Furthermore, the wet grinding is performed using a wet ball mill.

[0019] Preferably, the dry grinding time in step S2 is 30 to 60 minutes, and the dry grinding is performed until the average particle size of the magnesium slag is 10 to 20 μm. Furthermore, the dry grinding is performed using a high-energy ball mill.

[0020] Preferably, the ultrasonic frequency in step S4 is 20 to 100 kHz, and the time is 10 to 20 minutes.

[0021] In a second aspect, the present invention provides a composite reinforced recycled aggregate of organic silicon slag and magnesium slag prepared by the preparation method described in the first aspect.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1.The organic impurities in the organic silicon slag used in the present application are generally organic silane monomers, etc., which have good compatibility with alcohol amine grinding aids, can play the effect of surface modifier, and play the role of grinding aid in the ball milling process, thereby improving the grinding efficiency. The main component of the organic silicon slag is silicon powder, i.e. silicon dioxide, which is ground to nanoscale under the action of the alcohol amine grinding aid. On the one hand, it can react with Ca(OH)2 generated by the hydrolysis of magnesium slag powder to generate CSH gel, so that it is precipitated to the surface of the recycled aggregate; on the other hand, the nanoscale silicon powder particles have high reactivity and can enter the microcracks of the recycled aggregate to react with the alkaline substances therein to produce silicate gel to fill the cracks. At the same time, the alkaline environment of the microcracks is continuously improved, which also promotes the depolymerization-polycondensation reaction of the nanoscale silicon powder, thereby further enhancing the recycled aggregate.

[0024] 2.The main mineral components of the magnesium slag powder used in the present application are: γ-C2S, β-C2S, MgO and f-CaO, which can easily react to generate CSH gel in a water environment, and Ca 2+ , Mg 2+ , Fe 3+ , OH-ions are precipitated, wherein Ca 2+ , OH - can react with nanoscale silicon dioxide to produce silicate minerals; Mg 2+ , Fe 3+ can react with OH- to generate Mg(OH)2 and Fe(OH)3 which are insoluble in water. The alcohol amine grinding aid and the organic silane impurities in the organic silicon slag can adsorb the insoluble CSH gel, Mg(OH)2, Fe(OH)3 and metal cations generated by the reaction of nanoscale silicon powder and magnesium slag powder in a water environment, and can be adsorbed in the microcracks of the recycled aggregate, thereby playing a "bridging" role between them.

[0025] 3.The present application makes full use of the organic silicon slag as a silicon source and the magnesium slag as a calcium source, respectively uses wet grinding and dry grinding processes to improve the reactivity, provides reaction raw materials for filling the microcracks of the recycled aggregate, fully utilizes the resource properties of the organic silicon slag and the magnesium slag, realizes the comprehensive application of the three solid wastes including construction waste solid waste, reduces the pollution of solid waste to land, air and other environments, provides a technical path for enhancing the recycled aggregate, and has good economic and social benefits. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the present application more clear and definite, the present application is further described in detail through the following examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application.

[0027] Example 1

[0028] A kind of organic silicon slag and magnesium slag composite reinforced recycled aggregate, its preparation method specific steps are as follows:

[0029] S1: the organic silicon slag (the mass fraction of silicon dioxide is not less than 99%), deionized water, triethanolamine grinding aid is added into wet ball mill, wherein, the weight ratio of deionized water and organic silicon slag is 0.55:1, the amount of triethanolamine grinding aid is 0.7% of the weight of organic silicon slag, wet grinding 1.5h to the average particle size of organic silicon slag is 50-100nm, and organic silicon slag slurry is obtained;

[0030] S2: magnesium slag, triethanolamine grinding aid is added into high-energy ball mill, wherein, the amount of triethanolamine grinding aid is 1.2% of the weight of magnesium slag, dry grinding 45min to the average particle size of magnesium slag is 10-20 μm, and magnesium slag powder is obtained;

[0031] S3: magnesium slag powder, organic silicon slag slurry and deionized water are mixed uniformly according to the weight ratio of 1:4:70, and a suspension is obtained;

[0032] S4: the recycled aggregate is soaked in water, 50kHz ultrasonic treatment is carried out for 15min, the surface loose particles, silt, organic compounds and other impurities are removed, then the suspension obtained in step S3 is taken out, 200r / h stirring is carried out for 36h, after soaking, natural drying is carried out, and a kind of organic silicon slag and magnesium slag composite reinforced recycled aggregate is obtained.

[0033] (I) explore the influence of grinding aid on recycled aggregate

[0034] 1. Sample preparation

[0035] Example 2

[0036] A kind of organic silicon slag and magnesium slag composite reinforced recycled aggregate, its components and preparation method are basically same with example 1, and the difference lies in that the alcohol amine grinding aid added in steps S1 and S2 is triisopropanolamine grinding aid.

[0037] Example 3

[0038] A kind of organic silicon slag and magnesium slag composite reinforced recycled aggregate, its components and preparation method are basically same with example 1, and the difference lies in that the alcohol amine grinding aid added in steps S1 and S2 is diethanol monoisopropanolamine grinding aid.

[0039] Comparative example 1

[0040] A kind of organic silicon slag and magnesium slag composite reinforced recycled aggregate, its components and preparation method are basically same with example 1, and the difference lies in that no grinding aid is added in steps S1 and S2.

[0041] 2. Performance test:

[0042] The samples obtained in Examples 1-3 and Comparative Example 1 were tested for water absorption and crushing index according to the method described in GB / T 14685-2022 "Construction Gravel and Crushed Stone".

[0043] The above samples were prepared into C30 concrete test pieces with a basic mix ratio of 285 kg of P.O42.5 cement, 704 kg of quartz sand with a fineness modulus of 2.2, 1200 kg of continuously graded aggregate, 111 kg of municipal water, and 1% of a polycarboxylate superplasticizer with a solid content of 30% based on the mass of cement per cubic meter of concrete. Then, the 28d compressive strength of the concrete test pieces was tested according to the method described in GB / T 50081-2019 "Standard for Testing Methods of Mechanical Properties of Ordinary Concrete".

[0044] The test results are shown in Table 1.

[0045] Table 1 Performance testing of Examples 1-3 and Comparative Example 1

[0046] Performance indicators Water absorption / % Crushing index / % Compressive strength / MPa Example 1 0.9 10 39.1 Example 2 1.1 10 38.7 Example 3 1 11 39 Comparative Example 1 4.5 13 34.6

[0047] As can be seen from Table 1, under the same addition amount, different grinding aids have little effect on the performance of the recycled aggregate. Among them, the recycled aggregate obtained in Example 1 using triethanolamine as a grinding aid has the smallest water absorption and crushing index, and the maximum compressive strength of the concrete.

[0048] In Comparative Example 1, without using a grinding aid, the water absorption and crushing index of the recycled aggregate increase, and the compressive strength decreases, i.e., the performance of the recycled aggregate decreases.

[0049] (II) Effect of organic silicon slag slurry ratio on recycled aggregate

[0050] 1. Sample preparation

[0051] Example 4

[0052] A kind of organic silicon slag and magnesium slag composite reinforced recycled aggregate, its components and preparation method are basically same with example 1, its difference lies in that the weight ratio of deionized water and organic silicon slag mud in step S1 is 0.45:1.

[0053] Example 5

[0054] A kind of organic silicon slag and magnesium slag composite reinforced recycled aggregate, its components and preparation method are basically same with example 1, its difference lies in that the weight ratio of deionized water and organic silicon slag mud in step S1 is 0.60:1.

[0055] Comparative Example 2

[0056] A silicone slag and magnesium slag composite reinforced recycled aggregate, the components and preparation method thereof are basically the same as those of embodiment 1, and the difference lies in that the weight ratio of deionized water to silicone slag mud in step S1 is 0.40:1.

[0057] 2. Performance test:

[0058] The samples obtained from examples 4-5 and comparative example 2 were tested for water absorption and crushing index according to the method described in GB / T 14685-2022 "Construction Pebbles and Crushed Stones".

[0059] The above samples were prepared into C30 concrete test pieces, and the basic mix proportion of the C30 concrete test pieces was the same as above. Then, the 28d compressive strength of the concrete test pieces was tested according to the method described in GB / T 50081-2019 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete".

[0060] The test results are shown in Table 2.

[0061] Table 2 Performance test of examples 1, 4-5 and comparative example 2

[0062] Performance indicators Water absorption / % Crushing index / % Compressive strength / MPa Example 1 0.9 10 39.1 Example 4 1 11 39.2 Example 5 1.1 12 38.3 Comparative Example 2 1.1 11 39.0

[0063] As can be seen from Table 2, the various indexes in examples 1, 4-5 are relatively close, among which the compressive strength in example 4 is as high as 39.2 MPa. The compressive strength in example 5 is the smallest, which is 38.3 MPa. This is because different concentrations of silicone slag mud slurry have different reinforcing effects on recycled aggregate.

[0064] The water absorption of the recycled aggregate in comparative example 2 is 1.1%, the crushing index is 11, and the compressive strength is 39.0. It is relatively close to each example. This shows that increasing the concentration of silicone slag mud slurry does not significantly enhance the effect of recycled aggregate, but it is easy to cause resource waste.

[0065] (Three) Explore the effect of magnesium slag powder, silicone slag mud slurry and deionized water ratio on recycled aggregate

[0066] 1. Sample preparation

[0067] Example 6

[0068] A silicone slag and magnesium slag composite reinforced recycled aggregate, the components and preparation method thereof are basically the same as those of embodiment 1, and the difference lies in that the magnesium slag powder, silicone slag mud and deionized water are mixed in a weight ratio of 1:3:60 in step S3.

[0069] Example 7

[0070] A silicone slag and magnesium slag composite reinforced recycled aggregate, the components and preparation method are basically the same as those of example 1, the difference is that in step S3, the magnesium slag powder, the silicone slag mud slurry and the deionized water are mixed in a weight ratio of 1:3:80.

[0071] Comparative example 3

[0072] A silicone slag and magnesium slag composite reinforced recycled aggregate, the components and preparation method are basically the same as those of example 1, the difference is that in step S3, the magnesium slag powder, the silicone slag mud slurry and the deionized water are mixed in a weight ratio of 1:6:50.

[0073] 2. Performance test:

[0074] The samples obtained in examples 6-7 and comparative example 3 are tested for water absorption and crushing index according to the method described in GB / T 14685-2022 "Construction Pebbles and Crushed Stones".

[0075] The above samples are prepared into C30 concrete test pieces, and the basic mix proportion of the C30 concrete test pieces is the same as above. Then, the 28d compressive strength of the concrete test pieces is tested according to the method described in GB / T 50081-2019 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete".

[0076] The test results are shown in Table 3.

[0077] Table 3 Performance test of examples 1, 6-7 and comparative example 3

[0078] Performance indicators Water absorption / % Crushing index / % Compressive strength / MPa Example 1 0.9 10 39.1 Example 4 0.9 11 38.6 Example 5 1 10 38.8 Comparative Example 2 1.2 13 35.4

[0079] As can be seen from Table 3, the ratio of magnesium slag powder, silicone slag mud slurry and deionized water has a significant effect on the reinforcement effect of recycled aggregate. Among them, the performance of example 1 is better, the crushing index of example 6 is larger, and the compressive strength is smaller; the water absorption of example 7 is larger, and the compressive strength is smaller. But the data deviation of the three is not large.

[0080] In comparative example 3, the magnesium slag powder, the silicone slag mud slurry and the deionized water are mixed in a weight ratio of 1:6:50, and then the recycled aggregate is treated, and the water absorption and crushing index are larger, and the compressive strength is smaller. This shows that high concentration of magnesium slag powder and silicone slag mixed mud slurry will have a negative effect on the reinforcement effect of recycled aggregate.

[0081] (Four) Explore the effect of silicone slag treatment process on recycled aggregate

[0082] 1. Sample preparation

[0083] Comparative example 4

[0084] A composite reinforced recycled aggregate of organosilicon slag and magnesium slag, whose components and preparation method are basically the same as those in Example 1, except that the organosilicon slag in step S1 is replaced with pretreated organosilicon slag. The pretreatment method comprises: adding the organosilicon slag to a 75% ethanol solution, dissolving, centrifuging, washing with water, and re-centrifuging until the mass fraction of organosilane impurities in the organosilicon slag is less than 0.1%.

[0085] Comparative Example 5

[0086] A quartz sand and magnesium slag composite reinforced recycled aggregate, whose components and preparation method are basically the same as those in Example 1, except that the organosilicon slag in step S1 is replaced by a mixture of quartz sand and methyl silicone oil, wherein the mass fraction of silicon dioxide in the quartz sand is not less than 99%, and the amount of methyl silicone oil used is 1% of the weight of the quartz sand.

[0087] Comparative Example 6

[0088] A quartz sand and magnesium slag composite reinforced recycled aggregate, whose components and preparation method are basically the same as those in Example 1, except that the organosilicon slag in step S1 is replaced by quartz sand, and the mass fraction of silicon dioxide in the quartz sand is not less than 99%.

[0089] 2. Performance testing:

[0090] The samples obtained in Comparative Examples 4 to 6 were tested for their water absorption and crushing index according to the method described in GB / T 14685-2022 "Pebbles and crushed stones for construction".

[0091] The above samples were prepared into C30 concrete specimens with the same basic mix ratio as above. The 28-day compressive strength of the concrete specimens was then tested according to the method described in GB / T 50081-2019, "Standard for Test Methods of Mechanical Properties of Ordinary Concrete."

[0092] The test results are shown in Table 4.

[0093] Table 4 Performance test of Example 1 and Comparative Examples 4 to 6

[0094] Performance indicators Water absorption / % Crushing index / % Compressive strength / MPa Example 1 0.9 10 39.1 Comparative Example 4 1.3 12 34.3 Comparative Example 5 0.8 7 40.4 Comparative Example 6 1.2 13 35.6

[0095] From Table 4, the performance indicators of Example 1 and Comparative Example 5 are close, the water absorption rates are 0.9% and 0.8% respectively, the crushing indexes are 10 and 7 respectively, and both can reach the I-class standard in GB / T 14685-2022 "Construction with pebble, gravel". When used in C30 concrete, the 28d compressive strength is 39.1MPa and 40.4MPa respectively. The indicators in Example 1 are slightly smaller than those in Comparative Example 5, which is due to the fact that on the one hand, the purity of silicon dioxide in quartz sand is higher, and on the other hand, the interfacial wettability of methyl silicone oil with recycled aggregate is better than that of organosilane impurities in organosilicon slag, which can better play the bridging role of surfactants. However, it is worth noting that the high-purity quartz sand and methyl silicone oil used in Comparative Example 5 have high cost, and the feasibility of applying them to the strengthening of recycled aggregate is insufficient.

[0096] Comparative Example 4 and Comparative Example 6 are respectively treated with treated organosilicon slag and quartz sand to enhance the recycled aggregate, and the influence of organosilane impurities is minimized. The performance indicators of the two are relatively close, but both are smaller than Example 1 containing organosilane impurities and Comparative Example 5 containing methyl silicone oil, indicating that a small amount of organosilane impurities in organosilicon slag plays a bridging role, which also has a positive significance for the enhancement of recycled aggregate.

[0097] (Five) Explore the performance comparison of recycled aggregate and natural limestone treated by different processes

[0098] 1. Sample preparation

[0099] Comparative Example 7

[0100] A kind of construction waste recycled aggregate, namely the recycled aggregate treated by ultrasonic cleaning to remove surface impurities in step S4 of Example 1.

[0101] Comparative Example 8

[0102] A kind of natural limestone gravel for construction I.

[0103] 2. Performance test:

[0104] The samples obtained from Comparative Examples 7-8 were tested for water absorption and crushing index according to the method described in GB / T 14685-2022 "Construction with pebble, gravel".

[0105] The above samples were respectively prepared into C30 concrete test pieces, and the basic mix proportion of the C30 concrete test pieces was the same as above. Then, the 28d compressive strength of the concrete test pieces was tested according to the method described in GB / T 50081-2019 "Standard for testing methods of mechanical properties of ordinary concrete".

[0106] The test results are shown in Table 5.

[0107] Table 5 Performance test of Example 1 and Comparative Examples 6-7

[0108] Performance indicators Water absorption / % Crushing index / % Compressive strength / MPa Example 1 0.9 10 39.1 Comparative Example 7 8.3 17 24.5 Comparative Example 8 0.7 6 43.5

[0109] From table 5, it can be seen that the natural limestone for building I of the comparative example 8 has the best indicators, and the compressive strength can reach 43.5 MPa. The recycled aggregate treated by ultrasonic washing only in the comparative example 7 has poor performance, the water absorption rate is 8.3%, the crushing index is 17, and the compressive strength is only 24.5 MPa. The performance of the recycled aggregate in the example 1 reinforced by the composite of the organic silicon slag and the magnesium slag is obviously improved, and is close to the indicators of the natural limestone.

[0110] In conclusion, the recycled aggregate reinforced by the composite of the organic silicon slag and the magnesium slag provided by the application greatly improves the performance indicators of the construction waste recycled aggregate, makes it close to the natural limestone aggregate indicators, greatly improves the application range of the recycled aggregate, and has good social environmental benefits.

[0111] The above describes the preferred embodiments of the application, but it should be understood that the application is not limited to the limitations disclosed herein, and as long as the method concept and technical scheme of the application are adopted for non-essential improvements or applied to other occasions, they are within the protection scope of the application.

Claims

1. A method for preparing a composite of silicone slag and magnesium slag reinforced recycled aggregate, characterized in that, The method comprises the following steps: S1: mixing the organic silicon residue, water and alcohol amine grinding aid to wet grind for 1-2 hours to obtain an organic silicon residue slurry with an average particle size of 50-100 nm; S2: mixing the magnesium residue and alcohol amine grinding aid to dry grind for 30-60 minutes to obtain magnesium residue powder with an average particle size of 10-20 microns; S3: uniformly mixing the magnesium residue powder, the organic silicon residue slurry and water to obtain a suspension; the weight ratio of the magnesium residue powder, the organic silicon residue slurry and water is 1:(3-5):(60-80); S4: soaking the recycled aggregate in water, removing surface impurities through ultrasonic cleaning, then taking out and soaking in the suspension obtained in step S3, stirring at 100-300 r / h for 24-48 hours, and naturally drying after the soaking is completed to obtain the organic silicon residue and magnesium residue composite reinforced recycled aggregate.

2. The method of claim 1, wherein the method is characterized by, The alcohol amine grinding aid is at least one of triethanolamine, triisopropanolamine and diethanol monoisopropanolamine.

3. The method for preparing the composite reinforced recycled aggregate of organosilicon slag and magnesium slag according to claim 2, characterized in that: The weight ratio of the water to the organic silicon residue in step S1 is (0.45-0.60):1, and the alcohol amine grinding aid is used in an amount of 0.5%-1.0% of the mass of the organic silicon residue.

4. The method of claim 1, wherein the method is characterized by, The alcohol amine grinding aid is used in an amount of 0.5%-2% of the mass of the magnesium residue in step S2.

5. The method of claim 3, wherein the method is characterized by, The mass fraction of silicon dioxide in the organic silicon residue in step S1 is not less than 99%.

6. The method of claim 1, wherein the method is characterized by: The ultrasonic frequency in step S4 is 20-100 kHz, and the time is 10-20 minutes.

7. The organic silicon residue and magnesium residue composite reinforced recycled aggregate prepared by the preparation method in any one of claims 1-6.