Preparation method of lithium slag-based geopolymers with multi-dimensional fillers

Abstract

The present invention relates to a preparation method of a lithium slag-based geopolymers with multi-dimensional fillers, belonging to the technical field of building materials. In the present invention, lithium slag is uniformly mixed with NaOH, multi-dimensional fillers (zero-dimensional particles, one-dimensional fibers and two-dimensional film materials), modifiers, etc., and an appropriate amount of water and water glass are added for ball milling, and then poured, defoamed, and cured at room temperature in sequence to prepare a lithium slag-based geopolymers. The lithium slag-based geopolymers of the present invention is a dense and high-strength cementitious material with low production energy consumption, which can be applied to the large-scale production of building materials such as sidewalk bricks, curb stones and slope blocks, significantly improving the utilization rate of lithium slag and having significant economic and ecological benefits.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and particularly relates to a preparation method of a lithium slag geopolymer with multi-dimensional fillers. Background Art

[0002] Lithium has characteristics such as low density and active chemical properties, and is widely used in fields such as electronic devices and new energy vehicles. Lithium slag is the waste residue generated during the process of extracting lithium and its compounds from lithium-containing ores. Only in Yichun area of Jiangxi Province, the annual discharge of lithium slag reaches 2 million tons. The main chemical components of lithium slag are SiO2 and Al2O3, which is a kind of high-quality aluminosilicate mineral, but it contains a certain amount of sulfides and harmful elements, and simple stacking or landfill will cause harm to the surrounding soil and groundwater. The resource utilization of lithium slag mainly focuses on concrete (CN202010646107.9), cement mortar (CN202211670768.0), ceramics (CN202310470119.4), molecular sieves (CN 201911368434.6), etc., but the usage amount is very limited (<20%), which seriously restricts its large-scale utilization.

[0003] Geopolymer is a kind of aluminosilicate cementitious material, belonging to new type of green building materials, with characteristics such as corrosion resistance, high temperature resistance, and solidifying heavy metal ions, and is expected to partially replace cement products. The content of SiO2 and Al2O3 in lithium slag reaches 70%, meeting the raw material component requirements of geopolymer, but it contains more gypsum (CaSO4), resulting in low reaction activity and easy to form false setting, seriously affecting the performance of geopolymer. Therefore, lithium slag cannot be directly used to prepare geopolymer. At present, through calcination heat treatment (500 °C~700 °C), the content of glass phase in lithium slag is increased to obtain better reaction activity in alkaline solution, so as to be used to prepare geopolymer (Journal of Cleaner Production, 225 (2019) 1184-1193). Even so, it is still necessary to add active silica white, fly ash or steel slag externally to adjust the silicon-aluminum ratio and sodium-aluminum ratio in the raw material components (Construction and Building Materials, 342 (2022) 127952; Construction and Building Materials, 365 (2023) 130070).

[0004] The present invention uses multi-dimensional fillers and combines with ball milling process to prepare a lithium slag-based geopolymer. This new type of building material has excellent properties of strength and weather resistance, and is expected to be applied to sidewalk bricks, curb stones and slope blocks, providing technical support for the large-scale disposal and value-added utilization of lithium slag. Summary of the Invention

[0005] The object of the present invention is to provide a preparation method of a lithium slag-based geopolymers with multi-dimensional fillers. The synergistic effect of the multi-dimensional fillers lies in improving the density, compressive strength and reliability of the geopolymers, reducing the porosity and brittleness of the geopolymers, and improving the weather resistance, so that the lithium slag-based geopolymers can be used as a new type of green building material for engineering applications.

[0006] In order to achieve the above object of the invention, the present invention provides the following technical solutions:

[0007] A lithium slag-based geopolymers with multi-dimensional fillers and its preparation method, characterized by comprising the following steps:

[0008] Step S1: Mix lithium slag with NaOH, multi-dimensional fillers, modifiers, etc. evenly to obtain a mixed powder;

[0009] Step S2: Add an appropriate amount of water and water glass to the mixed powder in Step S1, and carry out ball milling to obtain a mixed slurry;

[0010] Step S3: Pour the mixed slurry in Step S2 into a mold, vibrate to remove bubbles, and cure at room temperature for 28 days to obtain a lithium slag-based geopolymers.

[0011] The dosage of NaOH in Step S1 is 4.5% of the mass of lithium slag.

[0012] The multi-dimensional fillers in Step S1 are composed of zero-dimensional particles, one-dimensional fibers and two-dimensional film materials. The zero-dimensional particles are one or more combinations of calcium carbonate, calcium hydroxide, and silica fume. The one-dimensional fiber is one of aluminum silicate, alumina, and mullite. The two-dimensional film material is graphene oxide. The addition amount of the multi-dimensional fillers is 2% - 5% of the mass of lithium slag.

[0013] The modifier in Step S1 is composed of fly ash / steel slag and borax. The dosage of fly ash / steel slag is 10% - 30% of the mass of lithium slag, and the dosage of borax is 3% of the mass of lithium slag;

[0014] The dosage of water in Step S2 is 10% of the mass of lithium slag; the modulus of water glass is 3.3, and its dosage is 40% of the mass of lithium slag; the ball milling time is 1 h - 4 h.

[0015] The lithium slag-based geopolymers with multi-dimensional fillers has an apparent density of 2.0 - 2.6 g / cm 3 , and a compressive strength of 30 - 60 MPa.

[0016] Compared with the prior art, the beneficial effects provided by the present invention are as follows:

[0017] (1) The multi-dimensional filler forms a three-dimensional network structure by filling the pores, strengthening the gel, significantly reducing the porosity of the geopolymer, and thus significantly increasing the apparent density and compressive strength of the geopolymer by more than 40% and 180% respectively.

[0018] (2) The multi-dimensional filler makes the distribution of raw material components more uniform. Combined with ball milling activation, it significantly improves the reaction activity of lithium slag, inhibits the negative impact of sulfate ions (false curing), generates more C-A-S-H gels, promotes the slow curing of the gel, and prevents crack formation, thereby preparing a high-strength and weather-resistant lithium slag-based geopolymer. Description of the Drawings

[0019] Figure 1 is a process flow chart for preparing a lithium slag-based geopolymer with a multi-dimensional filler.

[0020] Figure 2 is a physical photo of the lithium slag-based geopolymer in Example 1.

[0021] Figure 3 is a SEM photo of the lithium slag-based geopolymer in Example 1.

[0022] Figure 4 is a SEM photo of the lithium slag-based geopolymer in Example 2. Detailed Embodiments

[0023] The present invention is further illustrated by the following examples, but the content of the present invention is not limited to the content involved in the examples.

[0024] The preparation process flow of the present invention is as Figure 1 shown. Lithium slag is mixed evenly with NaOH, multi-dimensional filler, modifier, etc. An appropriate amount of water and water glass are added to the mixed powder, and ball milling is carried out to obtain a mixed slurry. The mixed slurry is poured into a mold, and after vibration and defoaming, it is cured at room temperature for 28 days to prepare a lithium slag-based geopolymer.

[0025] Comparative Example 1

[0026] Take 60 g of lithium slag, add 2.7 g of sodium hydroxide, 6 g of fly ash and 1.8 g of borax successively. After mixing evenly, add 6 g of water and 24 g of water glass and ball mill for 1 h. The ball-milled slurry is poured into a mold, vibrated and defoamed for 5 min, and cured at room temperature for 28 d to prepare a lithium slag-based geopolymer without filler. The apparent density of the sample is 1.83 g / cm 3 , and its compressive strength measured by a ceramic bending test machine is 20.6 MPa. Example 1

[0027] Take 60 g of lithium slag, and successively add 2.7 g of sodium hydroxide, 1.2 g of calcium carbonate powder, 6 g of fly ash, and 1.8 g of borax. After mixing evenly, add 6 g of water and 24 g of water glass and ball-mill for 1 h. The ball-milled slurry is poured into a mold, vibrated to remove bubbles for 5 min, and cured at room temperature for 28 d to prepare a lithium slag-based geopolymer with zero-dimensional (calcium carbonate) fillers. Figure 2 shows a physical photograph of the geopolymer. The micro-morphology was observed by SEM ( Figure 3 ), the surface of the sample is smooth and flat, with a small amount of pores and cracks. The apparent density of the sample is 2.04 g / cm 3 , and its compressive strength measured by a ceramic bending testing machine is 22.1 MPa. Compared with Comparative Example 1, after adding zero-dimensional calcium carbonate fillers, the apparent density and flexural strength of the geopolymer increased by 11.5% and 7.3% respectively. Example 2

[0028] Take 60 g of lithium slag, and successively add 2.7 g of sodium hydroxide, 1.2 g of calcium carbonate powder, 1.2 g of aluminum silicate fiber, 6 g of fly ash, and 1.8 g of borax. After mixing evenly, add 6 g of water and 24 g of water glass and ball-mill for 1 h. The ball-milled slurry is poured into a mold, vibrated to remove bubbles for 5 min, and cured at room temperature for 28 d to prepare a lithium slag-based geopolymer with zero-dimensional (calcium carbonate) and one-dimensional (aluminum silicate fiber) fillers. The micro-morphology was observed by SEM ( Figure 4 ), and the agglomeration of aluminum silicate fibers can be seen in the local area of the inner surface of the pores. The apparent density of the sample is 2.16 g / cm 3 , and its compressive strength measured by a ceramic bending testing machine is 30.5 MPa. Compared with Example 1, after adding one-dimensional aluminum silicate fiber fillers, the apparent density and compressive strength of the geopolymer increased by 5.9% and 38% respectively. Example 3

[0029] Take 60 g of lithium slag, and successively add 2.7 g of sodium hydroxide, 1.2 g of calcium carbonate, 1.2 g of aluminum silicate fiber, 0.06 g of graphene oxide, 6 g of fly ash, and 1.8 g of borax. After mixing evenly, add 6 g of water and 24 g of water glass and ball-mill for 1 h. The ball-milled slurry is poured into a mold, vibrated to remove bubbles for 5 min, and cured at room temperature for 28 d to prepare a lithium slag-based geopolymer with zero-dimensional (calcium carbonate), one-dimensional (aluminum silicate fiber) and two-dimensional (graphene oxide) fillers. The apparent density of the sample is 2.32 g / cm 3 , and its compressive strength measured by a ceramic bending testing machine is 42.8 MPa. Compared with Example 1, after adding one-dimensional aluminum silicate fiber and two-dimensional graphene oxide fillers, the apparent density and compressive strength of the geopolymer increased by 13.7% and 93.7% respectively Example 4

[0030] Take 60 g of lithium slag, and successively add 2.7 g of sodium hydroxide, 1.2 g of calcium carbonate, 1.2 g of alumina fiber, 0.1 g of graphene oxide, 12 g of fly ash, and 1.8 g of borax. After mixing evenly, add 6 g of water and 24 g of water glass, and ball mill for 4 h. The ball-milled slurry is poured into a mold, vibrated to remove bubbles for 5 min, and cured at room temperature for 28 d to prepare a lithium slag-based geopolymer added with zero-dimensional (calcium carbonate), one-dimensional (alumina fiber), and two-dimensional (graphene oxide) fillers. The apparent density of the sample is 2.45 g / cm 3 , and its compressive strength measured by a ceramic bending testing machine is 51.4 MPa. Compared with Example 3, by increasing the usage amounts of two-dimensional graphene filler and fly ash and prolonging the ball milling time of the slurry, the apparent density and compressive strength of the geopolymer are increased by 5.6% and 20% respectively. Compared with Comparative Example 1, the apparent density and compressive strength are increased by 33.9% and 149.5% respectively. Example 5

[0031] Take 60 g of lithium slag, and successively add 2.7 g of sodium hydroxide, 0.6 g of calcium carbonate, 0.6 g of calcium hydroxide, 0.6 g of silica fume, 1.1 g of mullite fiber, 0.1 g of graphene oxide, 18 g of steel slag, and 1.8 g of borax. After mixing evenly, add 6 g of water and 24 g of water glass, and ball mill for 4 h. The ball-milled slurry is poured into a mold, vibrated to remove bubbles for 5 min, and cured at room temperature for 28 d to prepare a lithium slag-based geopolymer added with zero-dimensional (calcium carbonate and silica fume), one-dimensional (alumina fiber), and two-dimensional (graphene oxide) fillers. The apparent density of the sample is 2.59 g / cm 3 , and its compressive strength measured by a ceramic bending testing machine is 59.6 MPa. Compared with Example 4, by using zero-dimensional fillers in combination with a steel slag modifier, the apparent density and compressive strength of the geopolymer are increased by 5.7% and 16% respectively. Compared with Comparative Example 1, the apparent density and compressive strength are increased by 41.5% and 189.3% respectively.

Claims

1. A preparation method of a lithium slag-based geopolymers with multi-dimensional fillers, characterized in that, It includes the following steps: Step S1: Mix lithium slag, NaOH, multi-dimensional filler, and modifier evenly to obtain a mixed powder; The multi-dimensional filler is composed of zero-dimensional particles as the basis, adding one-dimensional fibers and / or two-dimensional membrane materials. The zero-dimensional particles are one or more combinations of calcium carbonate, calcium hydroxide, and silica fume. The one-dimensional fiber is one of aluminum silicate, alumina, and mullite. The two-dimensional membrane material is graphene oxide. The addition amount of the multi-dimensional filler is 2% - 5% of the mass of lithium slag; The modifier is composed of fly ash / steel slag and borax; Step S2: Add an appropriate amount of water and sodium silicate to the mixed powder in Step S1, and carry out ball milling to obtain a mixed slurry; Step S3: Pour the mixed slurry in Step S2 into a mold, vibrate and defoam, and then cure at room temperature for 28 days to obtain a lithium slag-based geopolymer.

2. The preparation method according to claim 1, characterized in that: In Step S1, the usage amount of NaOH is 4.5% of the mass of lithium slag.

3. The preparation method according to claim 1, wherein: The usage amount of fly ash / steel slag is 10% - 30% of the mass of lithium slag, and the usage amount of borax is 3% of the mass of lithium slag.

4. The preparation method according to claim 1, characterized in that: In Step S2, the usage amount of water is 10% of the mass of lithium slag; the modulus of sodium silicate is 3.3, and its usage amount is 40% of the mass of lithium slag; the ball milling time is 1h - 4h.

5. The preparation method according to claim 1, characterized in that: The lithium slag-based geopolymers with the multi-dimensional fillers have an apparent density of 2.0~2.6 g / cm 3 , and a compressive strength of 30~60 MPa.

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