Sodium silicate powder exciting agent produced by melting method

Abstract

The invention belongs to the technical field of building material exciting agents, and particularly relates to a sodium silicate powder exciting agent produced through a melting method. The sodium silicate powder exciting agent is prepared by taking waste incineration fly ash, glass powder and sodium hydroxide as reactants through heat treatment. The powdery exciting agent is prepared instead of a traditional solution form, the possibility of a single-component alkali activation binder system is achieved, the waste incineration fly ash is selected as one of the raw materials, the production cost of the exciting agent is greatly reduced, and therefore the cost of alkali activation concrete is reduced; according to the present invention, the utilization rate of the waste incineration fly ash in the building field can be improved, the cement consumption and the energy consumption are reduced, the problems of environmental pollution and land occupation caused by solid waste stockpiling are improved, the dual-carbon emission reduction is promoted, and the prepared alkali activation binder mortar has excellent compressive strength.

Description

Technical Field

[0001] The invention belongs to the technical field of building material activators, and more specifically relates to an activator for producing sodium silicate powder by a melting method. Background Art

[0002] With the popularity of waste incineration power generation in my country, the production of fly ash has also increased year by year. Waste incineration fly ash is rich in toxic and harmful substances such as heavy metals and dioxins, which will cause secondary pollution to the ecological environment. Traditional cement solidification disposal is currently the main way to dispose of fly ash in my country's industry, but it has the defects of high carbon emissions, poor universality and low fly ash content. At present, the preparation of geopolymers by alkali activation of slag has attracted widespread attention from researchers because of its low carbon, green environmental protection, excellent mechanical strength and other characteristics. However, the application cost of alkali activators for geopolymers is high. For this reason, finding an activator that can activate slag geopolymers and maintain their mechanical properties has also become a research focus.

[0003] Among the common activators (hydroxides, silicates, sulfates, carbonates, acidic solutions), alkali hydroxide (sodium or potassium) combined with alkali silicate (also sodium or potassium) is favored because it has been shown to have high compressive strength when used with fly ash and slag as precursors. However, the use of alkali hydroxide and silicate solutions also has disadvantages. On the one hand, they are difficult to handle on site because they are highly alkaline liquid solutions, which poses health and safety risks. On the other hand, the costs, energy implications and environmental impacts associated with the production of activators cannot be ignored, especially the production of sodium silicate, which is usually produced by melting sodium hydroxide and silicon dioxide at temperatures of 1200-1400°C. This industrial process emits a large amount of carbon dioxide. Powdered anhydrous sodium silicate is available on the market, but it requires a pressure reactor vessel to be properly dissolved. In principle, powdered sodium silicate can be dissolved under normal atmospheric pressure conditions, but the availability of free Si in the solid powder is lower than that of liquid silicate. Therefore, the development of powdered sodium silicate activators is an inevitable trend.

[0004] At present, low-cost, environmentally friendly silicate activators are generally prepared by hydrothermal method, which is to heat silicon-rich raw materials in alkaline solution, among which temperature, selection of silicon-rich raw materials, particle size, and alkaline cation type will affect the dissolution rate. To increase the dissolution of silicon-rich raw materials, the temperature can be raised to between 150 and 250 ° C, but this requires a pressure reactor vessel because its self-generated pressure is as high as 30atm. The reaction solution is corrosive and may damage the pressure reactor vessel. Although it can be prepared at a temperature below 100 ° C, the dissolution rate is low. Based on the above problems, when it is applied to slag activation, compared with commercial water glass solution, due to the lower molar concentration, the maximum potential strength of the mortar precursor cannot reach the ideal value.

[0005] Therefore, how to develop a new preparation method so that the strength of the activator prepared by it can reach or exceed the effect of the existing commercial water glass solution when used for slag activation has become a difficult problem that technicians in this field need to overcome. Summary of the invention

[0006] The purpose of the present invention is to provide a sodium silicate powder activator produced by a melting process to solve the problems existing in the above-mentioned prior art.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] One of the technical solutions of the present invention is to provide a method for producing sodium silicate powder activator by melting method, the steps comprising:

[0009] The waste incineration fly ash, glass powder and sodium hydroxide are uniformly mixed and then subjected to heat treatment to obtain the sodium silicate powder activator.

[0010] Furthermore, the mass ratio of the waste incineration fly ash, glass powder and sodium hydroxide is 1:3:2.

[0011] Furthermore, the main component of the waste incineration fly ash is silicon dioxide, with a content of 16.13wt%.

[0012] Furthermore, the glass powder contains 57.82 wt % of amorphous silicon dioxide.

[0013] Furthermore, the method also includes a step of washing the waste incineration fly ash with water.

[0014] Preferably, the step of washing the waste incineration fly ash comprises:

[0015] The waste incineration fly ash is mixed with water, shaken in a water bath, and separated by vacuum filtration to obtain a solid product;

[0016] The solid product is dried to complete the water washing of the waste incineration fly ash.

[0017] More preferably, the mixing mass ratio of the waste incineration fly ash and water is 1:6.

[0018] More preferably, the water bath oscillation time is 10 min, the temperature is 25° C., and the oscillation frequency is 200 rpm.

[0019] More preferably, the drying temperature is 105° C. and the drying time is 24 hours.

[0020] Furthermore, the heat treatment temperature is 150° C. and the time is 1 hour.

[0021] The present invention pre-treats waste incineration fly ash by water washing, which can effectively remove water-soluble substances in the fly ash and relatively increase the proportion of silicon dioxide in the fly ash.

[0022] The second technical solution of the present invention is to provide a sodium silicate powder activator prepared by the above method.

[0023] The third technical solution of the present invention is to provide an application of the above-mentioned sodium silicate powder activator in the preparation of an alkali-activated adhesive.

[0024] The present invention discloses the following technical effects:

[0025] The activator prepared by the method of the present invention is a powder rather than a solution, making a single-component alkali-activated binder system possible. At the same time, glass powder is a silicon-rich material, and fly ash also contains a small amount of silicon. After the two are added, they react synergistically with each other and react with sodium hydroxide to produce more sodium silicate.

[0026] The activator prepared by the present invention is in powder form, rather than in the traditional solution form. The powder activator can be used to prepare a single-component alkali activating material, which is safer than a commercial strong alkaline liquid activator. At the same time, the packaging and use of the bonding material prepared by the powder activator are more similar to cement, and the use is more convenient and quick.

[0027] The present invention selects waste incineration fly ash as one of the raw materials, which greatly reduces the production cost of the activator, thereby reducing the cost of alkali-activated concrete, and can improve the utilization rate of waste incineration fly ash in the construction field. While reducing cement usage and energy consumption, it improves environmental pollution and land occupation problems caused by solid waste storage, and promotes dual carbon emission reduction.

[0028] The preparation method of the present invention adopts a low-temperature process and has a lower carbon footprint.

[0029] The alkali-activated binder mortar prepared by using the sodium silicate powder activator prepared by the invention has excellent compressive strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0031] Figure 1 This is a photo of the washed fly ash, glass powder and sodium hydroxide particles in Example 1 after being uniformly mixed in a square crucible;

[0032] Figure 2 This is the XRD diagram of the sodium silicate powder activator prepared using unwashed waste incineration fly ash in Example 2. DETAILED DESCRIPTION

[0033] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0034] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0035] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0036] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0037] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0038] Example 1

[0039] The preparation steps of sodium silicate powder activator are:

[0040] S1. Dry the waste incineration fly ash (silicon dioxide content of 16.13wt%) in an oven at 105°C for 24h, then mix it with water in a mass ratio of 1:6, and then put it into a constant temperature water bath horizontal oscillator for oscillation. The oscillation time is 10min, the temperature is 25°C, and the oscillation frequency is 200rpm. After the oscillation is completed, vacuum filtration is performed to obtain a solid product, and the solid product is dried in an oven at 105°C for 24h to obtain washed fly ash;

[0041] S2. Take 50 g of the washed fly ash in step S1, 150 g of glass powder (amorphous silicon dioxide content is 57.82 wt%), and 100 g of sodium hydroxide particles, mix them evenly in a square crucible, put them in a muffle furnace and heat them at 150° C. for 1 h to obtain a sodium silicate powder activator.

[0042] Example 2

[0043] The preparation steps of sodium silicate powder activator are:

[0044] 50 g of waste incineration fly ash (silicon dioxide content is 16.13 wt%), 150 g of glass powder (amorphous silicon dioxide content is 57.82 wt%), and 100 g of sodium hydroxide particles are mixed evenly in a square crucible, and then placed in a muffle furnace and heated at 150° C. for 1 h to obtain a sodium silicate powder activator.

[0045] Figure 1 This is a photo of the washed fly ash, glass powder and sodium hydroxide particles after being evenly mixed in a square crucible in Example 1.

[0046] Figure 2 The XRD pattern of the sodium silicate powder activator prepared from the unwashed waste incineration fly ash in Example 2 is shown in FIG. Figure 2 It can be seen that even if unwashed waste incineration fly ash is used, the main mineral of the product prepared is still sodium silicate, which shows that the sodium silicate powder activator prepared by the melting method adopted in the present invention is effective.

[0047] Test example

[0048] The sodium silicate powder activator prepared in Example 1 and Example 2, as well as the commercially available conventional activator sodium metasilicate (provided by Tianmao Baoding Biotechnology Co., Ltd., with the brand name Tianjin Damao) and sodium silicate (provided by Kainuo Trading Co., Ltd., with the brand name Tianjin Zhiyuan) were used to prepare five groups of mortars, with the proportions being: 360g slag, 90g activator, 1350g standard sand, and 225g water. The effect of the sodium silicate powder activator produced by the present invention on the mechanical properties of slag-based cementitious materials was explored, and the results are shown in Table 1.

[0049] Table 1

[0050] sample 3-day flexural strength / MPa 3-day compressive strength / MPa 7-day flexural strength / MPa 7-day compressive strength / MPa Example 1 1.4 20.13 1.6 34.97 Example 2 1.3 21.44 2.1 32.47 Sodium Metasilicate 1.6 31.94 2.3 33.20 Sodium silicate 1.4 34.31 2.0 35.19

[0051] It can be seen from the strength data in Table 1 that the mechanical properties of the sodium silicate powder activated slag-based cementitious material prepared from washed pretreated fly ash are improved within a certain range compared with the sodium silicate powder activated slag-based cementitious material prepared from unwashed fly ash.

[0052] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0053] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for producing sodium silicate powder activator by melting method, characterized in that the steps include: The waste incineration fly ash, glass powder and sodium hydroxide are uniformly mixed and then subjected to heat treatment to obtain the sodium silicate powder activator.

2. The method according to claim 1, characterized in that The mass ratio of the waste incineration fly ash, glass powder and sodium hydroxide is 1:3:

2.

3. The method according to claim 1, characterized in that The main component of the waste incineration fly ash is silicon dioxide, with a content of 16.13wt%.

4. The method according to claim 1, characterized in that: The glass powder contained 57.82 wt % of amorphous silicon dioxide.

5. The method according to claim 1, characterized in that The method also includes a step of washing the waste incineration fly ash with water.

6. The method according to claim 5, characterized in that The washing step of the waste incineration fly ash comprises: The waste incineration fly ash is mixed with water, shaken in a water bath, and separated by vacuum filtration to obtain a solid product; The solid product is dried to complete the water washing of the waste incineration fly ash.

7. The method according to claim 6, characterized in that The mixing mass ratio of the waste incineration fly ash and water is 1:6; the water bath oscillation time is 10 minutes, the temperature is 25° C., and the oscillation frequency is 200 rpm; the drying temperature is 105° C., and the drying time is 24 hours.

8. The method according to claim 1, characterized in that The heat treatment temperature is 150° C. and the time is 1 hour.

9. A sodium silicate powder activator obtained by the method according to any one of claims 1 to 8.

10. Use of the sodium silicate powder activator according to claim 9 in the preparation of an alkali-activated adhesive.

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