A method for preparing lithium slag geopolymer mixed with shell powder

Abstract

The present invention provides a method for preparing a lithium slag geopolymer incorporating shell powder, belonging to the field of comprehensive resource utilization technology. The method first involves thoroughly mixing a sodium silicate solution and solid sodium hydroxide to prepare an alkaline catalyst. Shell powder and other industrial waste are then mixed evenly, and the alkaline catalyst is added. Stirring is continued to allow for a thorough reaction to produce a first mixture. Water is then added to the first mixture and stirred again to produce a final slurry. Finally, the slurry is poured into a mold and cured to produce a shell powder-based geopolymer. This method significantly improves the compressive strength of the geopolymer.

Description

Technical Field

[0001] The invention relates to the technical field of comprehensive resource utilization, and in particular to a method for preparing a lithium slag geopolymer mixed with shell powder. Background Art

[0002] Traditional cement-based materials are the most widely used building materials in the world. The demand for cement-based materials is increasing rapidly due to infrastructure development and global population growth. Studies have found that the production of 1 ton of cement-based materials emits 0.85-1 ton of carbon dioxide (CO2). More importantly, CO2 emitted from the production of cement-based materials is a major cause of global warming, accounting for about 7% of total emissions. In addition, during the cement production process, a large amount of atmospheric pollutants are emitted (i.e., sulfur dioxide (SO2), nitrogen oxides (NO X ) and fine particulate matter (PM) are emitted into the atmosphere, causing environmental pollution and impacting human health. The building materials industry is one of China's largest industrial sectors in terms of energy consumption and carbon emissions, and is the largest source of CO2 emissions during industrial production. Therefore, cement must be (partially or completely) replaced by other low-carbon and environmentally friendly materials to maintain sustainability. Compared to conventional concrete, geopolymer concrete production reduces CO2 emissions by 50%-80% and requires approximately 60% less energy. Due to its lower carbon footprint and energy consumption, geopolymer production is considered the third generation of concrete binders for sustainable green building materials, following lime and cement.

[0003] Lithium is an important yet scarce energy material, crucial for the national economy and defense industry. However, the rapid growth in lithium product consumption has led to the emission of large amounts of lithium slag (LS) during production, creating serious environmental problems. Researchers have experimentally investigated the mechanical properties and partial durability of concrete containing varying amounts of LS (less than 30%), demonstrating that the addition of appropriate amounts of LS can improve the material's elastic modulus and subsequent compressive strength.

[0004] Oysters and scallops are the most farmed shellfish worldwide, generating millions of tons of shell waste annually. Inappropriate disposal methods contribute significantly to the pollution of farmland, water, and air. Shells, composed primarily of calcium carbonate (>90%) and a small amount of pyroclastic material, are a high-quality, renewable, natural biomineralized material. The mineral composition of shell flour is very similar to that of limestone flour used in the production of Portland lime cement; therefore, it has the potential to be a substitute for cement in the cement industry.

[0005] However, the study found that all mortars containing shell powder had sufficient strength and reduced drying shrinkage compared to traditional cement. There is currently little research on the incorporation of shell powder into lithium slag geopolymers, which not only has comparable performance to cement but also reduces cement usage.

[0006] Therefore, the use of shell powder as an aluminosilicate precursor in alkali-activated materials to address the problem of waste shell disposal was proposed. Research has found that compared with conventional cement, waste shell powder has comparable compressive strength, longer setting time, and lower density. This method maintains performance, reduces production costs, and promotes sustainable development. Summary of the Invention

[0007] The present invention provides a method for preparing a lithium slag geopolymer doped with shell powder. A high-strength lithium slag geopolymer adhesive material is produced from materials such as industrial waste and coastal garbage. The lithium slag geopolymer is prepared by adding shell powder as a gelling material. A uniaxial compression test is performed on the lithium slag geopolymer to obtain a compressive strength value of the lithium slag geopolymer adhesive material doped with shell powder. The compressive strengths are compared to obtain an optimal ratio of shell powder content to lithium slag content, thereby obtaining a better effect of improving the compressive strength of the lithium slag geopolymer.

[0008] In order to solve the above-mentioned purpose of the invention, the technical solution provided by the present invention is as follows:

[0009] A method for preparing lithium slag geopolymer doped with shell powder comprises the following steps:

[0010] S1. Fully blending the sodium silicate solution and the sodium hydroxide solid to prepare an alkaline catalyst;

[0011] S2, after uniformly stirring the shell powder, lithium slag and industrial waste for the first time, adding the alkaline catalyst, stirring for a second time to fully react, to obtain a first mixture;

[0012] S3, adding water to the first mixture and stirring for a third time to obtain a final slurry;

[0013] S4. Pour the slurry prepared in step S3 into a mold and perform curing to obtain a lithium slag geopolymer based on shell powder.

[0014] In step S1, the modulus of the sodium silicate solution is 3.24 (8.98% Na2O, 27.2% SiO2, 63.83% H2O), the purity of the sodium hydroxide spherical solid is 99%, and the sodium silicate solution and the sodium hydroxide solid are mixed in a mass ratio of 4:1 to obtain an alkaline catalyst. The alkaline catalyst is sealed and allowed to stand for 24 hours before use.

[0015] In step S2, the Ca content in the shell powder is not less than 95%, and the particle size of the shell powder does not exceed 100 mesh; the industrial waste includes fly ash, silica ash, and kaolin (generally, the fly ash particle size is 200-400 mesh, the silica ash particle size is 100-300 mesh, and the kaolin particle size is 325-4000 mesh). The chemical composition content in the industrial waste is as shown in Table 1.

[0016] Table 1 Chemical composition content in industrial waste

[0017]

[0018] In step S2, the mass ratio of shell powder: lithium slag: industrial waste: alkaline catalyst is 0.25-0.75: 0.25-0.75: 2.5: 1.

[0019] In step S2, the first stirring time is 3 minutes, and the second stirring time is not less than 6 minutes.

[0020] In step S3, the amount of water used is half the mass of the amount of the alkaline catalyst used, and the solid content of the obtained slurry is 72-80%.

[0021] In step S3, the third stirring time is 3 minutes.

[0022] In the step S4, the mixture is poured into the mold and then demoulded for 24 hours and placed in a curing box at 20±5° C. and a relative humidity of 95±5% for curing for 28 days.

[0023] The compressive strength of the lithium slag geopolymer obtained in step S4 is 38.54-40.01 MPa.

[0024] Lithium slag geopolymer mixed with shell powder is used in concrete binding materials.

[0025] Compared with the prior art, the above technical solution has at least the following beneficial effects:

[0026] The above scheme can utilize shell powder in combination with lithium to significantly improve the compressive strength of geopolymers; it can make full use of industrial waste and coastal garbage to reduce dependence on traditional energy, reduce energy consumption, thereby reducing pollution and damage to the environment and protecting the ecological environment; it can reduce the use of cement and reduce carbon dioxide gas emissions; the process flow of the present invention is relatively simple and more suitable for on-site application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 This is a process flow chart of a method for preparing lithium slag geopolymer mixed with shell powder according to the present invention;

[0029] Figure 2This is a bar graph of the compressive strength of lithium slag geopolymer mixed with shell powder in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0032] The present invention provides a method for preparing lithium slag geopolymer mixed with shell powder, such as Figure 1 As shown, the method includes the following steps:

[0033] S1. Fully blending the sodium silicate solution and the sodium hydroxide solid to prepare an alkaline catalyst;

[0034] S2, after uniformly stirring the shell powder, lithium slag, and industrial waste for the first time, adding the alkaline catalyst, stirring for a second time to fully react, to obtain a first mixture;

[0035] S3, adding water to the first mixture and stirring for a third time to obtain a final slurry;

[0036] S4. Pour the slurry prepared in step S3 into a mold and perform curing to obtain a lithium slag geopolymer based on shell powder.

[0037] In specific applications, the shell powder used is taken from the off-white shell powder of the Guangzhou Shell Processing Plant, which is off-white and powdery; the lithium slag is taken from the lithium slag obtained after lithium is extracted from lithium mica in a mine in Yichun, which is yellowish-brown and has fine particles; industrial waste: fly ash, silica ash, and high-quality territorial materials are all from a casting material company, all in powdery form; alkaline catalyst: sodium silicate solution has a modulus of 3.24 (8.98% Na2O, 27.2% SiO2, 63.83% H2O), and a purity of 99% sodium hydroxide spherical solid. The sodium silicate solution and sodium hydroxide solid are mixed in a mass ratio of 4:1 to obtain an alkaline catalyst.

[0038] Optimization of geopolymer sample preparation conditions: Based on a controlled variable design, shell powder was divided into three different concentrations: 5%, 10%, and 15%; the corresponding lithium slag was divided into three different concentrations: 15%, 10%, and 5%. The concentrations of other industrial waste materials, sodium silicate solution, and water were maintained at 55%, 20%, and 10%, respectively. This experiment was divided into three groups. Shell powder, lithium slag, and industrial waste materials (such as fly ash, silica fume, and high-altitude land) were weighed and placed in a blender and mixed evenly for 3 minutes. After stirring evenly, an alkaline catalyst was added and stirred until fully reacted. After adding an appropriate amount of water in proportion, stirring was continued for 6 minutes until the solution and the cementitious material were thoroughly mixed. The prepared slurry was then poured into a standard compression mold (40mm×40mm×160mm), with three parallel groups prepared for each group.

[0039] Curing of geopolymer samples: Place the prepared samples in a curing box with a temperature of (20±5)°C and a relative humidity of (95±5%) for a curing period of 28 days.

[0040] Compressive strength testing of geopolymer specimens: After 28 days of curing, the specimens were removed and polished flat on both the top and bottom surfaces to meet the flatness requirements for uniaxial compression testing. The uniaxial compression test was conducted using an electronic universal testing machine with a 40mm x 40mm fixture and a loading rate of 0.5mm / min. A computer recorded the entire test process, ultimately providing the specimen's stress-strain curve and maximum compressive strength. Three specimens were tested for each group, and the average value was taken as the final compressive strength value. The strength values ​​for the same group of specimens remained within ±15%. The maximum load of the universal electronic press was 100,000N, and the pressure sensor had an accuracy of 0.01N.

[0041] The following describes this with reference to specific embodiments.

[0042] Example 1

[0043] (1) Sodium silicate solution with a modulus of 3.24 and a purity of 99% sodium hydroxide spherical solid is used. Sodium silicate solution and sodium hydroxide are mixed to obtain an alkaline catalyst, which is then sealed and allowed to stand for 24 hours.

[0044] (2) adding 15% lithium slag, 5% shell powder, 44% fly ash, 3% silica fume, and 3% high-alkaline territories, adding them into a blender and mixing them evenly to obtain a first mixture, stirring them for more than 3 minutes for the first time, adding 20% ​​alkaline catalyst after the first stirring, stirring them for no less than 6 minutes for the second time, until the reaction is fully completed, thereby obtaining a first mixture;

[0045] (3) 10% water was added to the first mixture and stirred for a third time for 4 min to obtain the final slurry;

[0046] (4) The slurry obtained in step (3) is poured into a mold, demolded after 24 hours, and placed in a curing box at 20±5°C and a relative humidity of 95±5% for curing for 28 days to prepare a lithium slag geopolymer doped with shell powder.

[0047] Example 2

[0048] The specific method and steps are the same as those in Example 1, except that the lithium slag content and the shell powder content are changed to 10%, and a lithium slag geopolymer mixed with shell powder is prepared.

[0049] Example 3

[0050] The specific method and steps are the same as those in Example 1, except that the lithium slag content is changed to 5% and the shell powder content is changed to 15%, to prepare a lithium slag geopolymer mixed with shell powder.

[0051] Result detection

[0052] The lithium slag geopolymer prepared in the above example and mixed with shell powder was subjected to a uniaxial compression test in a 100KN electronic universal testing machine at a loading rate of 0.5mm / min. The results are shown in Table 1:

[0053] Table 1 The amount of raw materials added to lithium slag geopolymer mixed with shell powder

[0054]

[0055] Figure 2 The compressive strength values ​​of lithium slag geopolymers containing different shell powder contents are shown in Figure 1: Sample 1: lithium slag content of 15% and shell powder content of 5%, the compressive strength of the geopolymer is 38.54Mpa; Sample 2: lithium slag content of 10% and shell powder content of 10%, the compressive strength of the geopolymer is 41.12Mpa; Sample 3: lithium slag content of 5% and shell powder content of 15%, the compressive strength of the geopolymer is 40.01Mpa. As the shell powder content increases, the compressive strength of the geopolymer increases until it reaches a maximum value of 41.12Mpa when the lithium slag content is 10% and the shell powder content is 10%. When the shell powder content reaches 15%, the compressive strength decreases.

[0056] Lithium slag geopolymers prepared with varying amounts of shell powder according to this ratio exhibit superior compressive strength compared to those without shell powder. Using lithium slag geopolymers containing shell powder can address issues such as fully utilizing industrial waste and coastal garbage, reducing global cement consumption, and achieving the synergistic goals of green materials and environmental governance.

[0057] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for preparing lithium slag geopolymer mixed with shell powder, characterized in that: The steps are as follows: S1. Fully blending the sodium silicate solution and the sodium hydroxide solid to prepare an alkaline catalyst; S2, after uniformly stirring the shell powder, lithium slag and industrial waste for the first time, adding the alkaline catalyst, stirring for a second time to fully react, to obtain a first mixture; S3, adding water to the first mixture and stirring for a third time to obtain a final slurry; S4, pouring the slurry prepared in step S3 into a mold and curing it to obtain a lithium slag geopolymer based on shell powder; The industrial waste materials include fly ash, silica fume, and metakaolin; In step S2, the mass ratio of shell powder: lithium slag: industrial waste: alkaline catalyst is 0.25-0.75:0.25-0.75:2.5:

1.

2. The method for preparing lithium slag geopolymer mixed with shell powder according to claim 1, wherein In step S1, the modulus of the sodium silicate solution is 3.24, the purity of the sodium hydroxide spherical solid is 99%, the sodium silicate solution and the sodium hydroxide solid are mixed in a mass ratio of 4:1 to obtain an alkaline catalyst, and the alkaline catalyst is sealed and allowed to stand for 24 hours before use.

3. The method for preparing lithium slag geopolymer mixed with shell powder according to claim 1, wherein In step S2, the Ca content in the shell powder is not less than 95%, and the particle size of the shell powder does not exceed 100 mesh.

4. The method for preparing lithium slag geopolymer mixed with shell powder according to claim 1, wherein In step S2, the first stirring time is 3 minutes, and the second stirring time is not less than 6 minutes.

5. The method for preparing lithium slag geopolymer mixed with shell powder according to claim 1, wherein The amount of water used in step S3 is half the mass of the amount of the alkaline catalyst used, and the solid content of the obtained slurry is 72-80%.

6. The method for preparing lithium slag geopolymer mixed with shell powder according to claim 1, characterized in that: In step S3, the third stirring time is 3 minutes.

7. The method for preparing lithium slag geopolymer mixed with shell powder according to claim 1, characterized in that: In the step S4, the mixture is poured into the mold and then demoulded for 24 hours and placed in a curing box at 20±5° C. and a relative humidity of 95±5% for curing for 28 days.

8. The method for preparing lithium slag geopolymer mixed with shell powder according to claim 1, characterized in that: The compressive strength of the lithium slag geopolymer obtained in step S4 ranges from 38.54 to 40.01 MPa.

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