Preparation method of superfine early-strength mineral admixture based on solid waste reutilization

Abstract

The invention relates to a preparation method of a superfine early-strength mineral admixture based on solid waste reutilization, and belongs to the technical field of solid waste reutilization. The admixture is prepared by the following steps: performing multi-stage ultrafine grinding on mineral slag, steel slag, raw fly ash and manganese slag to prepare solid waste powder, and adding composite excitants Na2SiO3, AlCl3. 6H2O, citric acid, CaCl2. 2H2O and a UEA expanding agent, and dispersing agents polycarboxylate superplasticizer and nano SiO2. The high-activity early strength, low-shrinkage crack resistance and high solid waste utilization rate of the admixture are realized through solid waste synergistic activation, multi-stage grinding particle composition optimization and excitation-dispersion synergistic effect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solid waste recycling, and relates to a preparation method of superfine early-strength mineral admixture based on solid waste recycling. BACKGROUND

[0002] With the acceleration of industrialization, the production of solid wastes such as slag, steel slag, fly ash and manganese slag continues to increase. These solid wastes not only occupy a large amount of land resources, but also pose a serious threat to the ecological environment. By means of technology, solid wastes can be converted into building materials, which not only reduces environmental pollution, but also reduces the cost of raw materials. In Guangxi, there are rich mineral resources and various solid wastes, which provide a good foundation for the comprehensive utilization of solid wastes. However, the current technology has many challenges in solid waste recycling, which restricts the further improvement of its application value.

[0003] The current technology mainly uses single solid waste (such as slag powder) to prepare admixture, which not only limits the optimization of admixture performance, but also leads to insufficient economic and environmental benefits. For example, although slag powder has certain activity, its early strength is low, while solid wastes such as steel slag, fly ash and manganese slag have their own characteristics, and reasonable proportioning can significantly improve the comprehensive performance of the admixture. In addition, the traditional ball milling process can easily lead to particle size distribution deterioration during the preparation process, resulting in too fine or too coarse particles, increased water demand, and the activity of the admixture cannot be fully utilized.

[0004] In addition, the existing technology also has deficiencies in activation efficiency and early strength improvement. Conventional activators (such as NaOH) have poor activation effect on aluminum silicate-containing solid wastes such as manganese slag, and have high water demand, which limits their wide application. Existing early strength components (such as gypsum) can improve early strength, but often cause hydration heat concentration, increasing the risk of concrete cracking. Therefore, developing high-efficiency composite activators to improve the activity of solid wastes and introducing appropriate anti-cracking components to realize the synergy of early strength and anti-cracking is the key direction of future technology development. SUMMARY

[0005] The purpose of the present application is to provide a preparation method of superfine early-strength mineral admixture based on solid waste recycling, which uses local solid wastes (slag, steel slag, fly ash and manganese slag) in Guangxi as raw materials and prepares early-strength mineral admixture through multi-stage superfine grinding and composite activation synergy technology.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] A preparation method of superfine early-strength mineral admixture based on solid waste recycling, comprising the following steps:

[0008] (1) The slag, steel slag, fly ash, and manganese slag are sequentially ball-milled for 1-2 hours, vertically milled for 0.5-1 hours, and air-jet milled for 0.5-1 hours to obtain solid waste powder;

[0009] (2) Add 4.5-15% composite activator and 0.6-2.5% dispersant to the solid waste powder and mix evenly;

[0010] (3) The mixed solid waste powder is aged at room temperature for 24-48 hours to obtain the final ultrafine early strength mineral admixture.

[0011] As a preferred technical solution of the present invention, the mass ratio of slag, steel slag, fly ash, and manganese slag in step (1) is 40-60:15-30:10-20:10-20.

[0012] As a preferred embodiment of the present invention, in step (1), the ball milling is performed until the particle size of the material is 20-45 μm; the vertical milling is performed until the specific surface area of ​​the material is 400-500 m². 2 / kg; the air jet mill is used to grind the material to a particle size of 15-30μm.

[0013] As a preferred embodiment of the present invention, the composite activator in step (2) contains Na2SiO3, AlCl3·6H2O, and citric acid in a mass ratio of 3-8:1-5:0.5-2; Na2SiO3 serves as an alkaline activator, providing Na + and [SiO4] 4- It disrupts the glassy structure of slag and promotes Ca2+ production. 2+ Dissolution forms CSH gel; AlCl3·6H2O acts as an acidic activator, Al 3+ It reacts with SiO2 in the slag to form aluminosilicates, while Cl... - Accelerates C2S hydration in steel slag; citric acid acts as a retarder by chelating Ca... 2+ Delaying early hydration heat release avoids microcracks caused by temperature stress.

[0014] As a preferred embodiment of the present invention, the composite activator further comprises 0.5-3% CaCl2·2H2O and 0.5-3% UEA expanding agent; CaCl2·2H2O provides free Ca 2+ It promotes the rapid nucleation of AFt (ettringite) and enhances early strength; UEA expander contains calcium sulfoaluminate, which hydrates to form expandable ettringite, compensating for the drying shrinkage of ultrafine powder.

[0015] As a preferred technical solution of the present invention, the dispersant in step (2) contains polycarboxylate superplasticizer and nano-SiO2 in a mass ratio of 0.5-2:0.1-0.5.

[0016] The beneficial effects of the present application are as follows:

[0017] (1) The present application solves the problems of single type of traditional admixture solid waste and low utilization rate by synergistic compounding of four types of solid waste, i.e., slag, steel slag, fly ash and manganese slag, especially the activated utilization of manganese slag, thereby reducing the accumulation of industrial solid waste and environmental pollution.

[0018] (2) The present application uses three-stage grinding process of ball milling, vertical milling and jet milling to make the final particle size of the material reach 15-30 μm, the specific surface area ≥ 400 m 2 / kg, the particle surface defects increase, and the hydration activity is improved.

[0019] (3) The synergistic effect of alkaline (Na2SiO3) and acidic (AlCl3·6H2O) activators in the composite activator accelerates early hydration; citric acid delays the setting time to avoid rapid setting; CaCl2·2H2O and UEA expansion agent are used to achieve early strength and crack resistance. Polycarboxylic acid water reducer and nano-SiO2 dispersant effectively inhibit the agglomeration of ultra-fine powder. DETAILED DESCRIPTION

[0020] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined purpose, the specific embodiments, structures, features and effects according to the present application are described in detail as follows in combination with examples.

[0021] Example 1

[0022] A preparation method of ultra-fine early strength mineral admixture based on solid waste recycling, comprising the following steps:

[0023] (1) Ball milling slag, steel slag, fly ash and manganese slag for 1.5 h, vertical milling for 0.8 h and jet milling for 0.8 h to obtain solid waste powder;

[0024] (2) Adding 10% composite activator and 1.4% dispersant to the solid waste powder and uniformly mixing;

[0025] (3) Aging the mixed solid waste powder at room temperature for 36 hours to obtain the final ultra-fine early strength mineral admixture.

[0026] The mass ratio of slag, steel slag, fly ash and manganese slag in step (1) is 50:20:15:15.

[0027] The particle size of the material after ball milling is 35 μm; the specific surface area of the material after vertical milling is 450 m 2 / kg; and the particle size of the material after jet milling is 20 μm.

[0028] The composite activator in step (2) contains Na2SiO3, AlCl3·6H2O and citric acid in a mass ratio of 6:3:1.

[0029] The composite activator also contains 2% CaCl2·2H2O and 2% UEA expanding agent to achieve early strength and crack resistance synergy.

[0030] The dispersant in step (2) contains polycarboxylic acid water reducer and nano-SiO2 in a mass ratio of 1.5:0.3.

[0031] Example 2

[0032] A preparation method of superfine early strength mineral admixture based on solid waste recycling, comprising the following steps:

[0033] (1) Ball milling slag, steel slag, fly ash raw ash and manganese slag for 1h, vertical grinding for 0.5h and jet milling for 0.5h to obtain solid waste powder;

[0034] (2) Adding 15% composite activator and 2.5% dispersant to the solid waste powder and uniformly mixing;

[0035] (3) Aging the mixed solid waste powder at room temperature for 48 hours to obtain the final superfine early strength mineral admixture.

[0036] The mass ratio of slag, steel slag, fly ash raw ash and manganese slag in step (1) is 60:15:10:15.

[0037] The ball milling in step (1) is to a material particle size of 45μm; the vertical grinding is to a specific surface area of the material of 500m 2 / kg; and the jet milling is to a material particle size of 30μm.

[0038] The composite activator in step (2) contains Na2SiO3, AlCl3·6H2O and citric acid in a mass ratio of 8:5:2.

[0039] The composite activator also contains 3% CaCl2·2H2O and 3% UEA expanding agent to achieve early strength and crack resistance synergy.

[0040] The dispersant in step (2) contains polycarboxylic acid water reducer and nano-SiO2 in a mass ratio of 2:0.5.

[0041] Example 3

[0042] A preparation method of superfine early strength mineral admixture based on solid waste recycling, comprising the following steps:

[0043] (1) Ball milling slag, steel slag, fly ash raw ash and manganese slag for 2h, vertical grinding for 1h and jet milling for 1h to obtain solid waste powder;

[0044] (2) In the solid waste powder, 4.5% of the composite activator and 0.6% of the dispersant are added and uniformly mixed;

[0045] (3) The mixed solid waste powder is aged for 24 hours at room temperature to obtain the final superfine early strength mineral admixture.

[0046] The mass ratio of the slag, the steel slag, the fly ash raw ash and the manganese slag in step (1) is 40:30:20:10.

[0047] The ball milling in step (1) is to a material particle size of 20μm; the vertical milling is to a specific surface area of the material of 500m 2 / kg; and the jet milling is to a material particle size of 15μm.

[0048] The composite activator in step (2) contains Na2SiO3, AlCl3·6H2O and citric acid with a mass ratio of 3:1:0.5.

[0049] The composite activator further contains 0.5% of CaCl … ·2H2O and 0.5% of UEA expanding agent to realize the synergy of early strength and crack resistance.

[0050] The dispersant in step (2) contains polycarboxylate superplasticizer and nano-SiO2 with a mass ratio of 0.5:0.1.

[0051] Example 4

[0052] A superfine early strength mineral admixture preparation method based on solid waste recycling, comprising the following steps:

[0053] (1) The slag, the steel slag, the fly ash raw ash and the manganese slag are sequentially subjected to ball milling for 1.5h, vertical milling for 0.8h and jet milling for 0.8h to obtain a solid waste powder;

[0054] (2) In the solid waste powder, 10% of the composite activator and 1.4% of the dispersant are added and uniformly mixed;

[0055] (3) The mixed solid waste powder is aged for 36 hours at room temperature to obtain the final superfine early strength mineral admixture.

[0056] The mass ratio of the slag, the steel slag, the fly ash raw ash and the manganese slag in step (1) is 50:20:15:15.

[0057] The ball milling in step (1) is to a material particle size of 35μm; the vertical milling is to a specific surface area of the material of 450m 2 / kg; and the jet milling is to a material particle size of 20μm.

[0058] The composite activator in step (2) contains Na2SiO3, AlCl3·6H2O and citric acid in a mass ratio of 6:3:1.

[0059] The dispersant in step (2) contains polycarboxylate superplasticizer and nano-SiO2 in a mass ratio of 1.5:0.3.

[0060] Comparative Example 1

[0061] On the basis of Example 1, no slag is added to the solid waste, and the mass ratio of steel slag, fly ash raw ash and manganese slag is changed to 70:15:15, and the rest is consistent with Example 1.

[0062] Comparative Example 2

[0063] On the basis of Example 1, no steel slag is added to the solid waste, and the mass ratio of slag, fly ash raw ash and manganese slag is changed to 50:35:15, and the rest is consistent with Example 1.

[0064] Comparative Example 3

[0065] On the basis of Example 1, no fly ash raw ash is added to the solid waste, and the mass ratio of slag, steel slag and manganese slag is 50:20:30, and the rest is consistent with Example 1.

[0066] Comparative Example 4

[0067] On the basis of Example 1, no manganese slag is added to the solid waste, and the mass ratio of slag, steel slag, fly ash raw ash and manganese slag is changed to 65:20:15, and the rest is consistent with Example 1.

[0068] Comparative Example 5

[0069] On the basis of Example 1, no multi-stage grinding is performed, and only ball milling is performed to a material particle size of 20 μm, and the rest is consistent with Example 1.

[0070] Comparative Example 6

[0071] On the basis of Example 1, no multi-stage grinding is performed, and only vertical grinding is performed to a material particle size of 20 μm, and the rest is consistent with Example 1.

[0072] Comparative Example 7

[0073] On the basis of Example 1, no Na2SiO3 is added to the composite activator, and the mass ratio of AlCl3·6H2O and citric acid is 3:1, and the rest is consistent with Example 1.

[0074] Comparative Example 8

[0075] On the basis of Example 1, no AlCl3·6H2O is added to the composite activator, and the mass ratio of Na2SiO3 and citric acid is 6:1, and the rest is consistent with Example 1.

[0076] Comparative Example 9

[0077] On the basis of Example 1, only polycarboxylic water reducing agent was added as dispersant, and the rest was consistent with Example 1.

[0078] Comparative Example 10

[0079] On the basis of Example 1, only nano-SiO 2， and the rest was consistent with Example 1.

[0080] Comparative Example 11

[0081] On the basis of Example 1, no aging treatment was performed, and the rest was consistent with Example 1. Performance test:

[0082] The blended materials prepared in the examples and comparative examples were subjected to relevant performance tests, and the test results are shown in the table. Activity index: JG / T 486-2015; compressive strength: GB / T 7897-2008; dry shrinkage: GB / T 50082-2009.

[0083]

[0084]

[0085] From the above test results, it can be seen from Comparative Example 1 that slag is the core source of cementitious activity (containing CaO and SiO2), and after the absence, the 1d strength decreases to 8.2 MPa, and the activity index is only 65%, indicating that slag is crucial for early hydration.

[0086] From Comparative Example 4 (without manganese slag), it can be seen that the absence of manganese slag leads to a significant increase in dry shrinkage, and the absence of Mn 3+ catalyzes the densification of the cementitious network and the compensating effect of the UEA expansion agent.

[0087] From Comparative Examples 5-6, it can be seen that the multi-stage grinding process can improve the 28d strength.

[0088] From Comparative Example 7, it can be seen that the absence of alkaline activation leads to a decrease in pH, and the slag glass body is blocked, resulting in a significant decrease in 1d strength; by comparing Example and Comparative Example 8, it can be seen that the absence of acidic activator leads to insufficient generation of alumosilicate network, resulting in a decrease in 28d strength.

[0089] From Comparative Examples 9-10, it can be seen that without the dispersing effect of water reducing agent, it may lead to serious particle agglomeration, and the 1d strength decreases significantly.

[0090] From Comparative Example 11, it can be seen that without aging, the activator does not fully penetrate into the particle interior, resulting in a decrease in 1d strength due to insufficient pre-hydration reaction.

[0091] The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed with the preferred embodiments as above, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, as long as the changes or modifications do not deviate from the technical solution of the present application. Any indirect modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present application still belong to the scope of the technical solution of the present application.

Claims

1. A super-fine early-strength mineral admixture based on solid waste recycling, characterized in that: The solid waste powder is obtained by mixing slag, steel slag, fly ash raw ash and manganese slag in a mass ratio of 40-60:15-30:10-20:10-20, and then performing multi-stage superfine grinding.

2. The ultra-fine early-strength mineral admixture based on solid waste recycling according to claim 1, characterized in that: The multi-stage superfine grinding adopts ball milling, vertical milling and jet milling in sequence.

3. The ultra-fine early-strength mineral admixture based on solid waste recycling according to claim 2, characterized in that: The ball milling is performed to a material particle size of 20-45 mu m; the vertical milling is performed to a material specific surface area of 400-500 m2 / kg; and the jet milling is performed to a material particle size of 15-30 mu m.

4. The ultra-fine early-strength mineral admixture based on solid waste recycling according to claim 1, characterized in that: The composite activator contains Na2SiO3, AlCl3·6H2O and citric acid, and the mass ratio of Na2SiO3, AlCl3·6H2O and citric acid is 3-8:1-5:0.5-2.

5. The ultra-fine early-strength mineral admixture based on solid waste recycling according to claim 1, characterized in that: The dispersant contains polycarboxylic acid water reducer and nano-SiO2, and the mass ratio of polycarboxylic acid water reducer and nano-SiO2 is 0.5-2:0.1-0.

5. 6.The solid waste recycling based ultrafine early-strength mineral admixture according to claim 1 or 4, characterized in that: The composite activator further contains 0.5-3% CaCl2·2H2O and 0.5-3% UEA expanding agent, so as to realize the synergy of early strength and crack resistance.

7. The method for preparing the super-fine early-strength mineral admixture based on solid waste recycling according to any one of claims 1-6, characterized in that: The method comprises the following steps: (1) sequentially performing ball milling, vertical milling and jet milling on slag, steel slag, fly ash raw ash and manganese slag to obtain a solid waste powder; (2) adding a composite activator and a dispersant to the solid waste powder and uniformly mixing; (3) performing aging treatment on the mixed solid waste powder to obtain a final superfine early-strength mineral admixture.

8. The method for preparing a super-fine early-strength mineral admixture based on solid waste recycling according to claim 7, characterized in that: The ball milling time is 1-2 h, the vertical milling time is 0.5-1 h, and the jet milling time is 0.5-1 h.

9. The method for preparing a super-fine early-strength mineral admixture based on solid waste recycling according to claim 7, characterized in that: The aging treatment is performed at room temperature and lasts for 24-48 hours.

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