Lithium slag concrete and a method for preparing the same

Abstract

The application discloses a lithium residue concrete, which comprises cementitious material, sand, gravel and water, wherein the cementitious material is cement, fly ash and lithium residue, the mass ratio of the cement, fly ash and lithium residue is 4-6:1:1-2, and the lithium residue concrete further comprises water reducing agent and anti-adsorption agent, the content of the water reducing agent is 2.1%-3.0% of the mass of the cementitious material, the anti-adsorption agent is composed of sodium tripolyphosphate, methyl hexamethonium chloride dihydrate and choline chloride with a mass ratio of 8-11:1-3:4-6, and the content of the anti-adsorption agent is 0.1%-0.25% of the mass of the cementitious material. By adding the anti-adsorption agent composed of sodium tripolyphosphate, methyl hexamethonium chloride dihydrate and choline chloride with a reasonable ratio in the lithium residue concrete, the application reduces the dosage of the water reducing agent, improves the spread of the concrete, and makes the 28d strength greater than 48.2MPa, thereby providing a theoretical basis for large-scale resource utilization of the lithium residue, and having important significance for the development of the concrete industry.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, and in particular to a lithium slag concrete and its preparation method. Background Technology

[0002] Concrete refers to cementitious materials made by mixing cement as a binder, sand and gravel as aggregates, and water, admixtures, and additives in a certain proportion. It is widely used in civil engineering. Mineral admixtures such as fly ash, mineral powder, lithium slag, and carbide slag, as byproducts of other industries, are added to concrete as binders. This not only reduces cement usage but also mitigates the pollution caused by industrial waste. The active SiO2 contained in fly ash, mineral powder, and lithium slag undergoes a secondary reaction with hydration products such as CSH and CH produced during cement hydration—the so-called pozzolanic effect. This reaction strengthens the concrete, blocks capillary action, and improves its corrosion resistance.

[0003] Lithium slag is a waste product generated during the sulfuric acid process for producing lithium carbonate after calcining spodumene at 1200℃. Due to its high SiO2 and Al2O3 content, lithium slag can be used as a mineral admixture in concrete. Adding lithium slag to concrete can improve its pore structure, reduce shrinkage and permeability, and increase its elastic modulus. However, lithium slag has a large internal surface area and a porous structure, making it prone to adsorbing water-reducing agents and free water. This leads to significant slump loss and poor fluidity in the concrete. Therefore, increasing the amount of water-reducing agent in the preparation of lithium slag concrete is necessary to ensure slump and fluidity. However, increasing the amount of water-reducing agent can easily cause bleeding and caking, negatively impacting the widespread application of lithium slag concrete. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a lithium slag concrete that solves the problem of large water-reducing agent dosage in the existing technology when lithium slag is mixed into concrete.

[0005] The technical solution adopted by this invention to solve its technical problem is: a lithium slag concrete, comprising the following components in parts by weight: 300-350 parts of cementitious material, 800-1000 parts of sand, 1000-1100 parts of crushed stone, and 150-180 parts of water. The cementitious material is cement, fly ash, and lithium slag, and the mass ratio of cement, fly ash, and lithium slag is 4-6:1:1-2. It also includes a water-reducing agent and an anti-adsorption agent. The water-reducing agent content is 2.1%-3.0% of the cementitious material mass. The anti-adsorption agent is composed of sodium tripolyphosphate, methylhexammonium chloride dihydrate, and choline chloride in a mass ratio of 8-11:1-3:4-6, and the anti-adsorption agent content is 0.1%-0.25% of the cementitious material mass.

[0006] Furthermore, the cementitious material comprises the following components in parts by weight: 200-240 parts cement, 40-50 parts fly ash, and 50-70 parts lithium slag.

[0007] Furthermore, the water-reducing agent is a polycarboxylate water-reducing agent.

[0008] Furthermore, the lithium slag is a solid waste generated from spodumene through a sulfuric acid lithium extraction process, wherein the lithium content is ≥0.2%, SO3 ≤10%, and the specific surface area is 350–400 m². 2 / kg.

[0009] Furthermore, the sand is medium sand with a fineness modulus of 2.6 to 2.8.

[0010] Furthermore, the crushed stone is granite crushed stone, limestone or basalt crushed stone with a particle size range of 5 to 25 mm.

[0011] A method for preparing lithium slag concrete according to any one of the above-mentioned methods includes the following steps:

[0012] (1) Weigh out cement, fly ash, lithium slag, water-reducing agent, sand, crushed stone, anti-adsorption agent and water according to the mass fraction of each component above, and set aside.

[0013] (2) Mix cement, fly ash, lithium slag, sand and crushed stone evenly to obtain dry mix; add water-reducing agent and anti-adsorption agent to water to dissolve for 1-2 minutes, then add dry mix and stir for 3-5 minutes to obtain lithium slag concrete.

[0014] The beneficial effects of this invention are as follows: By adding an anti-adsorbent composed of sodium tripolyphosphate, methyl hexamethyl diammonium chloride dihydrate, and choline chloride in a reasonable ratio to lithium slag concrete, the amount of water-reducing agent used is reduced. While improving the scalability of the concrete, the 28-day strength is greater than 48.2 MPa. This invention will provide a theoretical basis for the large-scale resource utilization of lithium slag and is of great significance to the development of the concrete industry. Detailed Implementation

[0015] The present invention will be further described below with reference to embodiments.

[0016] Example 1:

[0017] (1) Weigh out the mass fractions of each component in Table 1: cement, fly ash, lithium slag, polycarboxylate superplasticizer, sand, crushed stone, sodium tripolyphosphate (STPP), methyl hexamethyl diammonium chloride dihydrate (HMTCI), choline chloride (CHC), and water for later use; among which, cement is P·O 42.5R, fly ash is F-II fly ash, and lithium slag is solid waste generated after lithium extraction from spodumene using sulfuric acid, with an SO3 content of 1% and a specific surface area of ​​370 m². 2 / kg, sand refers to medium sand with a fineness modulus of 2.6 to 2.8 and crushed stone refers to granite crushed stone with a particle size range of 5 to 25 mm, and the water reduction rate of polycarboxylate superplasticizer is 35%; in the table, the units of sodium tripolyphosphate (STPP), methyl hexamethyl diammonium chloride dihydrate (HMTCI), choline chloride (CHC), and water-reducing agent are the mass percentage of the total mass of cement, fly ash, and lithium slag, and the units of the other components are kg;

[0018] (2) Cement, fly ash, lithium slag, sand, and crushed stone were mixed evenly to obtain a dry mix. Water-reducing agent, sodium tripolyphosphate, methylhexammonium chloride dihydrate, and choline chloride were dissolved in water for 2 minutes, and then added to the dry mix and stirred for 5 minutes to obtain lithium slag concrete. The performance of the obtained lithium slag concrete was tested, and the results are shown in Table 2.

[0019] Table 1

[0020]

[0021]

[0022] The preparation methods for Examples 2 and 3 are the same as those for Example 1, and their proportions are shown in Table 1.

[0023] No anti-adsorbent was added in Comparative Example 1, only sodium tripolyphosphate (STPP) was added in Comparative Example 2, only methyl hexamethyl diammonium chloride dihydrate (HMTCI) was added in Comparative Example 3, and only choline chloride (CHC) was added as an anti-adsorbent in Comparative Example 4. The proportions of sodium tripolyphosphate, methyl hexamethyl diammonium chloride dihydrate, and choline chloride were different in Comparative Examples 5 and 6, but the other proportions were the same as in Example 1. The specific proportions are shown in Table 1.

[0024] Table 2

[0025] Expansion / mm Expansion after 2 hours / mm 28-day compressive strength / MPa Example 1 585 560 51 Example 2 580 550 49.3 Example 3 595 580 48.2 Comparative Example 1 420 300 50.7 Comparative Example 2 505 430 49.7 Comparative Example 3 510 450 50.3 Comparative Example 4 480 410 49.2 Comparative Example 5 450 320 51.8 Comparative Example 6 560 600 42.1

[0026] Compared to Comparative Example 1, Examples 1-3 showed a significant improvement in initial expansion, and the expansion loss after 2 hours also decreased significantly, indicating that the incorporation of sodium tripolyphosphate, methylhexamethyldiammonium chloride dihydrate, and choline chloride is beneficial to improving the adsorption of lithium slag. Comparative Examples 2-5 showed some improvement in initial expansion, but not significantly, and a large expansion loss after 2 hours. Comparative Example 6 had higher dosages of sodium tripolyphosphate, methylhexamethyldiammonium chloride dihydrate, and choline chloride, resulting in poor workability of the concrete mixture, bleeding and slurry formation, and poor stockpiling. After 2 hours, the expansion showed a reverse increase, the concrete segregated, and the 28-day compressive strength decreased significantly.

Claims

1. A lithium slag concrete, comprising the following components in parts by weight: 300-350 parts of cementitious material, 800-1000 parts of sand, 1000-1100 parts of crushed stone, and 150-180 parts of water, wherein the cementitious material is cement, fly ash, and lithium slag, and the mass ratio of cement, fly ash, and lithium slag is 4-6:1:1-2, characterized in that: It also includes a water-reducing agent and an anti-adsorption agent. The water-reducing agent is present at a content of 2.1% to 3.0% of the mass of the cementitious material. The anti-adsorption agent is composed of sodium tripolyphosphate, methyl hexamethyl diammonium chloride dihydrate and choline chloride in a mass ratio of 8 to 11:1 to 3:4 to 6. The anti-adsorption agent is present at a content of 0.1% to 0.25% of the mass of the cementitious material.

2. The lithium slag concrete according to claim 1, characterized in that: The cementitious material comprises the following components in parts by weight: 200-240 parts cement, 40-50 parts fly ash, and 50-70 parts lithium slag.

3. The lithium slag concrete according to claim 1, characterized in that: The water-reducing agent is a polycarboxylate water-reducing agent.

4. The lithium slag concrete according to claim 1, characterized in that: The lithium slag is a solid waste produced after lithium extraction from spodumene using a sulfuric acid process, containing a lithium content ≥0.2%, SO3 ≤10%, and a specific surface area of ​​350–400 m². 2 / kg.

5. The lithium slag concrete according to claim 1, characterized in that: The sand is medium sand with a fineness modulus of 2.6 to 2.

8.

6. The lithium slag concrete according to claim 1, characterized in that: The crushed stone is granite, limestone, or basalt crushed stone with a particle size range of 5–25 mm.

7. A method for preparing lithium slag concrete according to any one of claims 1 to 6, characterized in that, Includes the following steps: (1) Weigh out cement, fly ash, lithium slag, water-reducing agent, sand, crushed stone, anti-adsorption agent and water according to the mass fraction of each component above, and set aside. (2) Mix cement, fly ash, lithium slag, sand and crushed stone evenly to obtain dry mix; add water-reducing agent and anti-adsorption agent to water to dissolve for 1-2 minutes, then add dry mix and stir for 3-5 minutes to obtain lithium slag concrete.

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