All-solid waste building material and preparation method thereof

Abstract

The invention discloses a preparation method of an all-solid-waste building material, which comprises the following steps: S1, raw materials of the all-solid-waste building material comprise steel slag, lithium slag, carbide slag and water according to a mass ratio of (11-13): (4-6): 1: (2-4); s2, uniformly mixing and stirring the raw materials in the S1, casting and molding, curing for 2-3 days in an environment with the temperature of 15-25 DEG C and the humidity of 45-55%, and demolding; and S3, after demolding, carrying out carbonization maintenance in an environment with the temperature of 15-25 DEG C and the humidity of 45-55% to obtain the all-solid waste building material. According to the all-solid-waste building material and the preparation method thereof, the steel slag, the lithium slag and the carbide slag are adopted as raw materials, the building material with the strength reaching up to 30 Mpa is prepared, it is guaranteed that the compressive strength is not smaller than 24.3 Mpa, meanwhile, it is guaranteed that the drying shrinkage rate is smaller than 0.29%, the sulfate erosion resistance expansion rate is smaller than 0.07%, and the all-solid-waste building material can replace baking-free bricks to be used in buildings.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a solid waste building material and its preparation method. Background Technology

[0002] Concrete is one of the most important civil engineering materials in modern times. It is an artificial stone material made by mixing cementitious materials, granular aggregates (also known as aggregates), water, and, if necessary, admixtures and additives in a certain proportion, uniformly stirring, compacting, and curing. As of April 2023, the world produces more than 4 billion tons of concrete annually, so the demand and consumption of cement are also constantly increasing. In the cement production process, every ton of cement produced releases 0.68 to 1.12 tons of CO2, which has a significant impact on the environment.

[0003] Lithium slag is a byproduct of lithium salt production from spodumene processing. Spodumene (lepidolite) undergoes high-temperature transformation roasting at 1100–1200℃, followed by acidification roasting with concentrated sulfuric acid, neutralization leaching, and other steps to convert the lithium in the spodumene into a soluble lithium sulfate solution. The separated insoluble residue, after drying, becomes lithium slag. The SiO2 and Al2O3 in lithium slag are mostly in amorphous form, thus exhibiting high pozzolanic activity, making it an ideal building material raw material. Because lithium ore has a very low lithium content, processing it produces a large amount of lithium slag; for every ton of lithium salt produced, 8–10 tons of lithium slag are generated. Currently, lithium slag is mainly used in building materials and ceramic raw materials. Due to its pozzolanic activity, lithium slag can replace cement in concrete preparation, but it needs to be mixed with cement and other materials, resulting in low usage and low economic benefits. Large quantities of lithium slag are still simply stockpiled for disposal, polluting the environment.

[0004] Furthermore, the rapid development of the steel and chemical industries has led to a year-on-year increase in the discharge of steel slag and calcium carbide slag. However, due to the stability issues of steel slag and the impurities and high water content in calcium carbide slag, they have not been efficiently utilized. The accumulation of large amounts of steel slag and calcium carbide slag pollutes the environment and hinders the green development of the steel and chemical industries. While some use steel slag and calcium carbide slag as admixtures in concrete, currently, these industrial byproducts are merely used as mineral admixtures, working in conjunction with cement to minimize cement usage while ensuring concrete performance. This is because the absence of cement would result in insufficient flowability and / or compressive strength in the concrete. Therefore, industrial waste is currently used only as an admixture in concrete applications, rather than being fully utilized as a building material. Therefore, if a building material could be prepared using the aforementioned industrial solid waste, it would offer a green solution to the problems of high energy consumption in cement production and low utilization rates of industrial solid waste. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a solid waste building material and its preparation method, which yields a solid waste building material with a strength of up to 30MPa, realizing the resource utilization of lithium slag, steel slag and carbide slag.

[0006] The technical solution adopted by this invention to solve its technical problem is: a method for preparing all-solid-waste building materials, comprising the following steps:

[0007] S1. The raw materials of the all-solid waste building material include steel slag, lithium slag, carbide slag and water, and the mass ratio of steel slag, lithium slag, carbide slag and water is 11-13:4-6:1:2-4;

[0008] S2. Mix the raw materials from S1 evenly and then pour them into the mold. Cure them in an environment with a temperature of 15-25℃ and a humidity of 45-55% for 2-3 days before demolding.

[0009] S3. After demolding, carbonize and cure in an environment with a temperature of 15-25℃ and a humidity of 45-55% to obtain all-solid waste building materials.

[0010] Furthermore, step S3 involves carbonizing and curing until complete carbonization.

[0011] Furthermore, step S3 involves carbonization curing for 4–8 days.

[0012] Furthermore, the CO2 concentration in step S3, carbonization curing, is 19-21%.

[0013] Furthermore, the carbon dioxide source for the carbonization curing in step S3 is industrial exhaust gas.

[0014] Furthermore, the steel slag is a by-product of the iron and steel industry, with a fineness modulus of 2.8 to 3.0.

[0015] Furthermore, the lithium slag is a byproduct generated during the production of lithium sulfate using the sulfuric acid process after calcination of spodumene, wherein the lithium content is ≥0.2%, SO3 ≤10%, and the specific surface area is 350–400 m². 2 / kg.

[0016] Furthermore, the calcium carbide slag is a fine powder obtained by grinding the waste residue after obtaining acetylene gas from calcium carbide hydrolysis. Its main component is calcium hydroxide (Ca(OH)2), and its specific surface area is 500-600 m². 2 / kg.

[0017] A building material made entirely of solid waste, wherein the building material is prepared by any of the above-described methods for preparing a building material made entirely of solid waste.

[0018] Furthermore, the all-solid-waste building material can replace non-fired bricks in construction.

[0019] The beneficial effects of this invention are: This invention provides a solid waste building material and its preparation method, which uses steel slag, lithium slag and carbide slag as raw materials to prepare a building material with a strength of up to 30 MPa. While ensuring a compressive strength of not less than 24.3 MPa, it also ensures a drying shrinkage rate of less than 0.29% and a sulfate erosion expansion rate of less than 0.07%, and can replace non-fired bricks in construction.

[0020] High-value utilization of CO2, lithium slag, and steel slag in industrial waste gas reduces the consumption of natural resources in the production of ordinary building materials; each ton of waste carbon-fixing building material can fix at least 180 kg of CO2, and each ton of waste carbon-fixing building material can utilize at least 571 kg of steel slag, 238 kg of lithium slag, and 45 kg of calcium carbide slag. Detailed Implementation

[0021] The present invention will be further described below with reference to embodiments.

[0022] Example 1:

[0023] S1. Prepare the raw materials for the all-solid-waste building materials: 1200g steel slag, 500g lithium slag, 100g calcium carbide slag, and 300g water. The steel slag is a byproduct of the iron and steel industry, with a fineness modulus of 3.0. The lithium slag is a byproduct generated during the production of lithium sulfate using the sulfuric acid process after calcining spodumene. The calcium carbide slag is a fine powder obtained by grinding the waste residue from the hydrolysis of calcium carbide to obtain acetylene gas; its main component is calcium hydroxide (Ca(OH)2), with a specific surface area of ​​500–600 m² / g. 2 / kg;

[0024] S2. After mixing the above raw materials evenly, pour them into a test block of 40mm×40mm×160mm and cure for 3 days in an environment with a temperature of 20±5℃ and a humidity of 50±5% before demolding.

[0025] S3. After demolding, industrial exhaust gas with a carbon dioxide concentration of 20±1% is introduced, that is, carbonization and curing for 6 days in an environment with a temperature of 20±5℃, humidity of 50±5%, and CO2 volume fraction of 20±1% to achieve complete carbonization, thus obtaining all-solid waste building materials.

[0026] Example 2:

[0027] S1. Prepare the raw materials for the all-solid-waste building materials: 1100g steel slag, 600g lithium slag, 100g calcium carbide slag, and 250g water. The steel slag is a byproduct of the iron and steel industry, with a fineness modulus of 3.0. The lithium slag is a byproduct generated during the production of lithium sulfate using the sulfuric acid process after calcining spodumene. The calcium carbide slag is a fine powder obtained by grinding the waste residue from the hydrolysis of calcium carbide to obtain acetylene gas; its main component is calcium hydroxide (Ca(OH)2), with a specific surface area of ​​500-600 m² / g. 2 / kg;

[0028] S2. After mixing the above raw materials evenly, pour them into a test block of 40mm×40mm×160mm and cure for 3 days in an environment with a temperature of 20±5℃ and a humidity of 50±5% before demolding.

[0029] S3. After demolding, industrial exhaust gas with a carbon dioxide concentration of 20±1% is introduced, that is, carbonization and curing for 6 days in an environment with a temperature of 20±5℃, humidity of 50±5%, and CO2 volume fraction of 20±1% to achieve complete carbonization, thus obtaining all-solid waste building materials.

[0030] Example 3:

[0031] S1. Prepare the raw materials for the all-solid-waste building materials: 1300g steel slag, 400g lithium slag, 100g calcium carbide slag, and 350g water. The steel slag is a byproduct of the iron and steel industry, with a fineness modulus of 3.0. The lithium slag is a byproduct generated during the production of lithium sulfate using the sulfuric acid process after calcining spodumene. The calcium carbide slag is a fine powder obtained by grinding the waste residue from the hydrolysis of calcium carbide to obtain acetylene gas; its main component is calcium hydroxide (Ca(OH)2), with a specific surface area of ​​500–600 m² / g. 2 / kg;

[0032] S2. After mixing the above raw materials evenly, pour them into a test block of 40mm×40mm×160mm and cure for 3 days in an environment with a temperature of 20±5℃ and a humidity of 50±5% before demolding.

[0033] S3. After demolding, industrial exhaust gas with a carbon dioxide concentration of 20±1% is introduced, that is, carbonization and curing for 6 days in an environment with a temperature of 20±5℃, humidity of 50±5%, and CO2 volume fraction of 20±1% to achieve complete carbonization, thus obtaining all-solid waste building materials.

[0034] Comparative Example 1: (No carbonization, otherwise the same as Example 1)

[0035] S1. Prepare the raw materials for the all-solid-waste building materials: 1200g steel slag, 500g lithium slag, 100g calcium carbide slag, and 300g water. The steel slag is a byproduct of the iron and steel industry, with a fineness modulus of 3.0. The lithium slag is a byproduct generated during the production of lithium sulfate using the sulfuric acid process after calcining spodumene. The calcium carbide slag is a fine powder obtained by grinding the waste residue from the hydrolysis of calcium carbide to obtain acetylene gas; its main component is calcium hydroxide (Ca(OH)2), with a specific surface area of ​​500–600 m² / g. 2 / kg;

[0036] S2. After mixing the above raw materials evenly, pour them into a test block of 40mm×40mm×160mm and cure for 3 days in an environment with a temperature of 20±5℃ and a humidity of 50±5% before demolding.

[0037] S3. After demolding, continue carbonization and curing in an environment with a temperature of 20±5℃ and a humidity of 50±5% for 6 days to obtain the all-solid waste building material.

[0038] Comparative Example 2: (Lithium slag: Calcium carbide slag = 1:1, other details are the same as in Example 1)

[0039] S1. Prepare 1200g of steel slag, 300g of lithium slag, 300g of calcium carbide slag, and 300g of water as raw materials for all-solid-waste building materials. The steel slag is a byproduct of the iron and steel industry, with a fineness modulus of 3.0. The lithium slag is a byproduct generated during the production of lithium sulfate using the sulfuric acid process after calcining spodumene. The calcium carbide slag is a fine powder obtained by grinding the waste residue from the hydrolysis of calcium carbide to obtain acetylene gas; its main component is calcium hydroxide (Ca(OH)2), with a specific surface area of ​​500-600 m² / g. 2 / kg;

[0040] S2. After mixing the above raw materials evenly, pour them into a test block of 40mm×40mm×160mm and cure for 3 days in an environment with a temperature of 20±5℃ and a humidity of 50±5% before demolding.

[0041] S3. After demolding, industrial exhaust gas with a carbon dioxide concentration of 20±1% is introduced, that is, carbonization and curing for 7 days in an environment with a temperature of 20±5℃, humidity of 50±5%, and CO2 volume fraction of 20±1% to achieve complete carbonization, thus obtaining all-solid waste building materials.

[0042] Comparative Example 3: (Lithium slag: Calcium carbide slag = 9:1, other details are the same as in Example 1)

[0043] S1. Prepare the raw materials for the all-solid-waste building materials: 1200g steel slag, 450g lithium slag, 50g calcium carbide slag, and 300g water. The steel slag is a byproduct of the iron and steel industry, with a fineness modulus of 3.0. The lithium slag is a byproduct generated during the production of lithium sulfate using the sulfuric acid process after calcining spodumene. The calcium carbide slag is a fine powder obtained by grinding the waste residue from the hydrolysis of calcium carbide to obtain acetylene gas; its main component is calcium hydroxide (Ca(OH)2), with a specific surface area of ​​500-600 m² / g. 2 / kg;

[0044] S2. After mixing the above raw materials evenly, pour them into a test block of 40mm×40mm×160mm and cure for 3 days in an environment with a temperature of 20±5℃ and a humidity of 50±5% before demolding.

[0045] S3. After demolding, industrial exhaust gas with a carbon dioxide concentration of 20±1% is introduced, that is, carbonization and curing in an environment with a temperature of 20±5℃, humidity of 50±5%, and CO2 volume fraction of 20±1% for 4 days to achieve complete carbonization, thus obtaining all-solid waste building materials.

[0046] The performance of the all-solid-waste building materials prepared in the examples and comparative examples was tested according to GB / T750-1992, and the results are shown in Table 1.

[0047] Table 1

[0048]

[0049] As shown in Table 1, the carbonization process significantly improves the strength, volume stability, sulfate resistance, and stability of the waste residue carbonization material. This is because, after carbonization, CSH, which causes volume changes, f-CaO, which causes stability issues, and Ca(OH)2, which is susceptible to sulfate attack, are all converted into CaCO3, which has better volume and chemical stability. Furthermore, due to its larger molar volume, CaCO3 can better compact the waste residue carbonization material, improving its strength and further enhancing its durability.

[0050] Comparative Examples 2 and 3 show that both excessively high and low ratios of lithium slag to carbide slag (alkaline activator) are detrimental to the strength development of waste slag carbonization materials. This is because a high ratio of lithium slag to carbide slag prevents proper activation of the lithium slag, resulting in fewer hydration products and a weaker structure in the waste slag carbonization material. Furthermore, the limited amount of carbide slag (Ca(OH)2) forming CaCO3 after carbonization makes it difficult to create a dense structure, thus leading to lower strength in the waste slag carbonization material. Conversely, a low ratio of lithium slag to carbide slag results in insufficient hydration products after activation to form a strong structure, while the abundant Ca(OH)2 forming CaCO3 after carbonization tends to clump together rather than create a dense structure, resulting in a still low strength in the prepared waste slag carbonization material.

Claims

1. A method for preparing an all-solid-waste building material, characterized in that, Includes the following steps: S1. The raw materials of the all-solid waste building material include steel slag, lithium slag, carbide slag and water, and the mass ratio of steel slag, lithium slag, carbide slag and water is 11-13:4-6:1:2-4; S2. Mix the raw materials from S1 evenly and then pour them into the mold. Cure them in an environment with a temperature of 15-25℃ and a humidity of 45-55% for 2-3 days before demolding. S3. After demolding, carbonize and cure in an environment with a temperature of 15-25℃ and a humidity of 45-55% to obtain all-solid waste building materials.

2. The method for preparing a solid waste building material according to claim 1, characterized in that: Step S3 involves carbonization and curing until complete carbonization.

3. The method for preparing a solid waste building material according to claim 1, characterized in that: The carbonization curing process in step S3 lasts for 4–8 days.

4. The method for preparing a solid waste building material according to claim 1, characterized in that: In step S3, the CO2 concentration for carbonization curing is 19-21%.

5. The method for preparing a solid waste building material according to claim 4, characterized in that: The carbon dioxide source for the carbonization curing in step S3 is industrial exhaust gas.

6. The method for preparing a solid waste building material according to claim 1, characterized in that: The steel slag is a by-product of the iron and steel industry, with a fineness modulus of 2.8 to 3.

0.

7. The method for preparing a solid waste building material according to claim 1, characterized in that: The lithium slag is a byproduct generated during the production of lithium sulfate using the sulfuric acid process after calcination of spodumene. It contains ≥0.2% lithium, ≤10% SO3, and has a specific surface area of ​​350–400 m². 2 / kg.

8. The method for preparing a solid waste building material according to claim 1, characterized in that: The calcium carbide slag is a fine powder produced by grinding the waste residue from the hydrolysis of calcium carbide to obtain acetylene gas. Its main component is calcium hydroxide (Ca(OH)2), and its specific surface area is 500-600 m². 2 / kg.

9. A building material made entirely from solid waste, characterized in that: The all-solid-waste building material is prepared by any one of the preparation methods of all-solid-waste building materials described in any one of 1 to 8.

10. A solid waste building material according to claim 9, characterized in that: The aforementioned solid waste building materials can replace non-fired bricks in construction.

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