Lithium slag-based unfired light ceramsite and its preparation method and application

Abstract

The present invention specifically relates to lithium slag-based unfired light ceramsite, its preparation method, and application, belonging to the field of building materials technology. The raw materials for the lithium slag-based unfired light ceramsite, measured by weight, include: 60-80 parts lithium slag, 10-20 parts cement, 8-15 parts quicklime, 3-8 parts alkali activator, 1-6 parts foaming agent, and 12-20 parts water. The unfired light ceramsite prepared by the present invention has high cylinder compressive strength, low bulk density, and low water absorption, and can be used in ceramsite insulation materials.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and particularly relates to a lithium slag-based unfired light ceramsite and a preparation method and application thereof. Background Art

[0002] With the continuous development of new energy vehicles, energy storage, and other fields, the market demand for new energy batteries continues to increase. Major companies are increasing investment and expanding lithium production to meet market demand. As demand for lithium products increases rapidly, the storage of lithium slag, a byproduct of the process, has caused serious ecological and environmental problems.

[0003] Currently, the lithium residue from spodumene is mainly used in the cement, concrete and other building materials industries. Patent CN103601230A discloses a method for the comprehensive utilization of lithium slag to produce chemical raw materials. The method obtains calcium chloride, ammonium fluoride, white carbon black, aluminum salt and ammonium sulfate through the steps of reacting lithium slag with hydrochloric acid and filtering. The patent has high requirements for equipment during the operation process. At the same time, the steps are complicated and the operation is difficult. Its industrial application needs to be studied. Patent CN 111302708A discloses a large-scale lithium slag waste comprehensive utilization technology and its implementation method. The method uses lithium slag, admixtures, activators, water reducers and chelating agents to prepare lithium slag oligomers to replace ordinary cement-based cementitious materials. Although the patent solves the problem of lithium slag waste utilization rate, it requires the lithium slag to undergo pre-treatment processes such as drying and grinding, which has a high production cost. Patent CN 113511848A discloses a comprehensive utilization method for lithium slag, a byproduct of lithium ore. This patent uses lithium slag and alkali to produce water glass, which is then mixed with fly ash, red mud, cement, and sand and gravel to produce unfired bricks. This patent requires the use of large amounts of strong alkali and the drying of the lithium slag. Patent CN 108273826A discloses a method for the full-phase, high-value recycling of lithium slag. This patent uses slurry mixing, carbonate reaction, and magnetic separation to produce pyrophyllite raw material for glass fiber. This method requires crystallization to recover the sulfate product, which has disadvantages such as high costs and is difficult to achieve industrial application.

[0004] Ceramic aggregate is a new type of building material. It is made from clay, mudstone, industrial waste, and other raw materials, mixed with a small amount of binders and activators, and processed into granules to form a man-made lightweight aggregate. It has excellent properties such as low density, high cylinder compressive strength, high softening coefficient, and good frost resistance. Currently, ceramic aggregate is mainly divided into fired and unfired types. The production process of fired ceramic aggregate is complex and costly, requiring high-temperature kilns and other equipment, and consuming a lot of electricity. Unfired lightweight ceramic aggregate, on the other hand, has a simpler production process, lower costs, and has promising application prospects.

[0005] Ceramsite wall insulation materials offer advantages such as excellent thermal insulation, low price, and easy construction, making them a promising development for energy-saving building wall materials. However, if the ceramsite has a high water absorption rate, the water consumption during mixing will increase significantly, disrupting the mortar's setting cycle and significantly reducing the mortar's mechanical properties. This can easily lead to hollowing and cracking, seriously affecting the thermal performance and durability of the entire insulation system. Patent CN111205061A discloses a method for preparing unfired high-strength fly ash ceramsite. While the ceramsite produced has a relatively high cylinder compressive strength, its bulk density and water absorption are both relatively high, making it unsuitable for use in ceramsite insulation materials. Summary of the Invention

[0006] To address the problem that existing ceramsite cannot simultaneously achieve high cylinder compressive strength, low bulk density, and low water absorption, the present invention provides a lithium slag-based unfired light ceramsite, as well as its preparation method and application. This method uses the residue from acid-processed lithium extraction from spodumene concentrate as a gelling material, which is then blended with cement, quicklime, an alkaline activator, a foaming agent, and water. The resulting lithium slag-based unfired light ceramsite exhibits the excellent properties of high cylinder compressive strength, low bulk density, and low water absorption.

[0007] The invention provides lithium slag-based unfired light ceramsite. The raw materials of the ceramsite include, by weight, 60-80 parts of lithium slag, 10-20 parts of cement, 8-15 parts of quicklime, 3-8 parts of alkali activator, 1-6 parts of foaming agent and 12-20 parts of water.

[0008] In a specific embodiment of the present invention, the lithium slag is the residue after lithium extraction from spodumene concentrate by acid method, and its composition is as follows, in weight percentage: SiO2 53-59%, Al2O3 21-24%, SO3 5-9%, CaO 3-6%, Na2O 0.3-1.0%, K2O 0.2-0.5%, Fe2O3 0.8-1.5%; the moisture content of the lithium slag is 10%-25%; the fineness of the lithium slag satisfies 95% passing through a 0.3 mm sieve hole and 70% passing through a 0.075 mm sieve hole.

[0009] In the present invention, the chemical composition of the lithium slag is approximately HAlSi2O6, which has a porous structure and a large internal surface area. Silicon and aluminum mainly exist in the form of amorphous SiO2 and Al2O3. Therefore, it has high pozzolanic activity and can undergo secondary hydration reaction with cement to form hydrated calcium silicate gel. While ensuring the cylinder pressure strength, it can also reduce the bulk density of the unfired light ceramsite.

[0010] In a specific embodiment of the present invention, the cement is 425 ordinary Portland cement; the effective calcium oxide content of the quicklime is above 90%.

[0011] In the present invention, the cement is 425 ordinary Portland cement, which has good plasticity and adhesion and is a highly alkaline material. Cement hydration precipitates a large amount of Ca(OH)2, which uses its alkalinity to corrode lithium slag, releasing more SiO2 and Al2O3 and reacting with them, thereby increasing the activity of the lithium slag. At the same time, the cement helps the material to form balls and improves the mechanical properties of ceramsite. The quicklime is a white powder with an effective calcium oxide content of more than 90%. It is both an active stimulant and a major component of the cementitious material. It reacts with water to produce Ca(OH)2, and the generated Ca(OH)2 can undergo a polymerization reaction with SiO2 and Al2O3 in the lithium slag. The quicklime's stimulation of the lithium slag ultimately produces Ca(OH)2, which not only provides a cracking effect on the lithium slag but also provides the calcium source required for the lithium slag to be hydrated to form the cementitious material.

[0012] In a specific embodiment of the present invention, the alkaline activator is one or more of water glass or sodium hydroxide; preferably, the alkaline activator is water glass, the water glass modulus is 1.5 to 3, and the concentration is 3 to 5%.

[0013] In a specific embodiment of the present invention, the foaming agent is one or more of sodium bicarbonate and ammonium bicarbonate.

[0014] The present invention also provides a method for preparing lithium slag-based unfired light ceramsite, comprising the following steps:

[0015] S1: Weigh 60-80 parts of lithium slag, 10-20 parts of cement, 8-15 parts of quicklime, 3-8 parts of alkali activator, 1-6 parts of foaming agent and 12-20 parts of water according to the weight ratio and set aside;

[0016] S2: The cement, quicklime, and foaming agent weighed in step S1 are mixed in a mixer and stirred for 10 to 30 minutes. After the stirring is completed, lithium slag is added and stirred again for 10 to 20 minutes. During the stirring process, water is added to obtain a mixed material;

[0017] S3: The mixed material is fed into a press and a disc granulator via a conveyor belt to start granulation, and an alkali activator is sprayed at the same time to obtain a ceramsite green body;

[0018] S4: The ceramsite green body granulated in step S3 is placed in a curing box for curing or natural curing to obtain unfired light ceramsite.

[0019] In a specific embodiment of the present invention, in step S3, the rotation speed of the disc granulator is 30-35 rpm, the inclination angle is 50°-60°, and the temperature is 20-40°C; and the particle size of the ceramsite embryo is 5-20 mm.

[0020] In a specific embodiment of the present invention, in step S4, the curing temperature of the curing box is 80-100°C, the humidity is 85-95%, and the curing time is 20-24 hours; the natural curing is curing under natural conditions for 27 days.

[0021] In a specific embodiment of the present invention, the cylinder compressive strength of the unburned light ceramsite is 6.37-9.41 MPa, and the bulk density is 614.6-867.3 kg / m 3 The 24h mass water absorption rate is 8.7~11.4%.

[0022] The present invention also provides the use of the lithium slag-based unfired light ceramsite in ceramsite wall insulation materials.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The raw materials used in the lithium slag-based unfired light ceramsite and its preparation method provided by the present invention are mainly lithium slag, which can effectively reuse resources, reduce pollution and protect the ecological environment.

[0025] 2. The lithium slag used in the present invention is the residue from lithium extraction from spodumene, which has a high moisture content and does not require drying equipment for preparing ceramsite.

[0026] 3. The preparation method of the lithium slag-based unfired light ceramsite provided by the present invention does not require sintering, has a simple and controllable process flow, low raw material prices, and low energy consumption; it is green and environmentally friendly, has a low apparent density, high cylinder pressure strength, and excellent comprehensive performance. It can be widely used in the fields of building materials and thermal insulation materials, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a process flow chart for preparing lithium slag-based unfired light ceramsite. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0029] Example 1

[0030] A lithium slag-based unfired light ceramsite is composed of the following components in parts by weight: 70 parts of lithium slag, 15 parts of 425 ordinary Portland cement, 12 parts of quicklime, 6 parts of water glass, 3 parts of sodium bicarbonate and 16 parts of water.

[0031] The method for preparing the lithium slag-based unfired light ceramsite specifically comprises the following steps:

[0032] S1. Weigh each component according to the above parts by weight and set aside.

[0033] S2. 425 ordinary Portland cement, quicklime and sodium bicarbonate were mixed in a mixer and stirred for 20 min to obtain a premix, and then lithium slag was added and stirred for 10 min. During the stirring process, 16 parts of water were added in equal parts by weight to obtain a mixture.

[0034] S3, the mixture is input into a press and a disc granulator through a conveyor belt to start granulation, and 6 parts of water glass are sprayed at the same weight parts. By controlling the disc granulator speed at 33 rev / min, the inclination angle at 55°, and the temperature at 30°C, a ceramsite green body with a diameter of 5-20 mm is prepared.

[0035] S4. Place the ceramic green body formed into balls in step S3 into a steam curing box for curing for 24 hours, then take it out and cure it under natural conditions for 27 days to obtain the lithium slag-based unfired light ceramsite; wherein the curing box is maintained at a temperature of 90° C. and a humidity of 90%.

[0036] Example 2

[0037] A lithium slag-based unfired light ceramsite is composed of the following components in parts by weight: 60 parts of lithium slag, 10 parts of 425 ordinary Portland cement, 8 parts of quicklime, 3 parts of sodium hydroxide, 1 part of ammonium bicarbonate and 12 parts of water.

[0038] The method for preparing the lithium slag-based unfired light ceramsite specifically comprises the following steps.

[0039] S1. Weigh each component according to the corresponding parts by weight and set aside.

[0040] S2. 425 ordinary Portland cement, quicklime and ammonium bicarbonate were mixed in a mixer and stirred for 20 min to obtain a premix, and then lithium slag was added and stirred for 10 min. During the stirring process, 12 parts of water were added in equal parts by weight to obtain a mixture.

[0041] S3, the mixture is input into a press and a disc granulator through a conveyor belt to start granulation, and 3 parts of sodium hydroxide are sprayed at the same weight parts. By controlling the disc granulator speed at 33 rev / min, the inclination angle at 55°, and the temperature at 30°C, a ceramsite green embryo with a diameter of 5-20 mm is prepared.

[0042] S4. Place the ceramic green body formed into balls in step S3 into a steam curing box for curing for 24 hours, then take it out and cure it under natural conditions for 27 days to obtain the lithium slag-based unfired light ceramsite; wherein the curing box is maintained at a temperature of 90° C. and a humidity of 90%.

[0043] Example 3

[0044] A lithium slag-based unfired light ceramsite is composed of the following components in parts by weight: 80 parts of lithium slag, 20 parts of 425 ordinary Portland cement, 15 parts of quicklime, 8 parts of an alkali activator (6 parts of water glass and 2 parts of sodium hydroxide), 6 parts of sodium bicarbonate and 20 parts of water.

[0045] The method for preparing the lithium slag-based unfired light ceramsite specifically comprises the following steps.

[0046] S1. Weigh each component according to the corresponding parts by weight and set aside.

[0047] S2. 425 ordinary Portland cement, quicklime and sodium bicarbonate were mixed in a mixer and stirred for 20 min to obtain a premix, and then lithium slag was added and stirred for 10 min. During the stirring process, 20 parts by weight of water were added to obtain a mixture.

[0048] S3, the mixture is input into a press and a disc granulator by a conveyor belt to start granulation, and 8 parts of alkali activators (6 parts of water glasses and 2 parts of sodium hydroxide) are sprayed at the same weight parts. By controlling the disc granulator speed at 33 revs / min, the inclination angle at 55° and the temperature at 30°C, a ceramsite green embryo with a diameter of 5-20mm is prepared.

[0049] S4. Place the ceramic green body formed into balls in step S3 into a steam curing box for curing for 24 hours, then take it out and cure it under natural conditions for 27 days to obtain the lithium slag-based unfired light ceramsite; wherein the curing box is maintained at a temperature of 90° C. and a humidity of 90%.

[0050] Example 4

[0051] A lithium slag-based unfired light ceramsite is composed of the following components in parts by weight: 70 parts of lithium slag, 15 parts of 425 ordinary Portland cement, 12 parts of quicklime, 6 parts of water glass, 3 parts of sodium bicarbonate and 16 parts of water.

[0052] The method for preparing the lithium slag-based unfired light ceramsite specifically comprises the following steps.

[0053] S1. Weigh each component according to the corresponding parts by weight and set aside.

[0054] S2. Cement, quicklime and sodium bicarbonate were mixed in a mixer and stirred for 10 min to obtain a premix, and then lithium slag was added and stirred for 10 min. During the stirring process, 16 parts of water were added in equal parts by weight to obtain a mixture.

[0055] S3, the mixture is input into a press and a disc granulator through a conveyor belt to start granulation, and 6 parts of water glass are sprayed at the same weight parts. By controlling the disc granulator speed at 30 rev / min, the inclination angle at 50°, and the temperature at 20°C, a ceramsite green body with a diameter of 5-20 mm is prepared.

[0056] S4. Place the ceramic green body formed into balls in step S3 into a steam curing box for curing for 20 hours, then take it out and cure it under natural conditions for 27 days to obtain the lithium slag-based unfired light ceramsite; wherein the curing temperature in the curing box is 80° C. and the humidity is 85%.

[0057] Example 5

[0058] A lithium slag-based unfired light ceramsite is composed of the following components in parts by weight: 70 parts of lithium slag, 15 parts of 425 ordinary Portland cement, 12 parts of quicklime, 6 parts of an alkali activator (5 parts of water glass and 1 part of sodium hydroxide), 3 parts of sodium bicarbonate and 16 parts of water.

[0059] The method for preparing the lithium slag-based unfired light ceramsite specifically comprises the following steps.

[0060] S1. Weigh each component according to the corresponding parts by weight and set aside.

[0061] S2. 425 ordinary Portland cement, quicklime and sodium bicarbonate were mixed in a mixer and stirred for 30 min to obtain a premix, and then lithium slag was added and stirred for 20 min. During the stirring process, 16 parts of water were added in equal parts by weight to obtain a mixture.

[0062] S3, the mixture is input into a press and a disc granulator by a conveyor belt to start granulation, and 6 parts of alkali activators (5 parts of water glasses and 1 part of sodium hydroxide) are sprayed at the same weight parts. By controlling the disc granulator speed at 35 rev / min, the inclination angle at 60° and the temperature at 40°C, a ceramsite green embryo with a diameter of 5-20mm is prepared.

[0063] S4, placing the ceramic green body after being balled in step S3 into a steam curing box for curing for 24 hours, then taking it out and curing it under natural conditions for 27 days to obtain the lithium slag-based unfired light ceramsite; wherein the curing temperature of the curing box is 100° C. and the humidity is 95%.

[0064] Comparative Example 1

[0065] Disclosed is unburned light ceramsite, which is composed of the following components in parts by weight: 70 parts of fly ash, 15 parts of 425 ordinary Portland cement, 12 parts of quicklime, 6 parts of water glass, 3 parts of sodium bicarbonate and 16 parts of water.

[0066] The method for preparing the unfired light ceramsite specifically comprises the following steps.

[0067] S1. Weigh each component according to the corresponding parts by weight and set aside.

[0068] S2. 425 ordinary Portland cement, quicklime and sodium bicarbonate were mixed in a mixer and stirred for 20 minutes to obtain a premix, and then fly ash was added and stirred for 10 minutes. At the same time, 16 parts of water were added in equal parts by weight during the stirring process to obtain a mixture.

[0069] S3, the mixture is input into a press and a disc granulator through a conveyor belt to start granulation, and 6 parts of water glass are sprayed at the same weight parts. By controlling the disc granulator speed at 33 rev / min, the inclination angle at 55°, and the temperature at 30°C, a ceramsite green body with a diameter of 5-20 mm is prepared.

[0070] S4. Place the ceramic green body formed into balls in step S3 into a steam curing box for curing for 24 hours, then take it out and cure it under natural conditions for 27 days to obtain the unfired light ceramsite; wherein the curing temperature in the curing box is 90° C. and the humidity is 90%.

[0071] The properties of the unburned light ceramsite prepared in Examples 1-5 and Comparative Example 1 were measured in accordance with the light aggregate test method in Part 2 of GB / T17431 "Light Aggregates and Their Test Methods". The results are shown in the following table.

[0072] Table 1. Test results of properties of unburned light ceramsite prepared in Examples 1-5 and Comparative Example 1

[0073] project <![CDATA[Bulk density (kg / m 3 )]]> Cylinder pressure strength (MPa) 24h water absorption (%) Example 1 679.4 8.35 10.5 Example 2 867.3 9.41 8.7 Example 3 614.6 6.37 11.4 Example 4 705.5 8.66 9.2 Example 5 661.7 8.02 9.8 Comparative Example 1 953.2 9.88 17.6

[0074] Note: 24h water absorption refers to the 24h mass water absorption.

[0075] The data in the table show that the bulk density of the ceramsite obtained in Examples 1 to 5 is 610 to 870 kg / m 3 , cylinder compressive strength is 6.3-9.5 MPa, and 24-hour mass water absorption is 8.7-11.4%. Compared with the comparative example, the 24-hour water absorption rate of the unburned light ceramsite prepared by the present invention is much lower than that of the unburned light ceramsite prepared using fly ash, and the bulk density is also reduced. The cylinder compressive strength does not change much, indicating that the present invention has high application value.

[0076] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Lithium slag-based unfired light ceramsite, characterized in that: The raw materials of the ceramsite include, by weight, 60-80 parts of lithium slag, 10-20 parts of cement, 8-15 parts of quicklime, 3-8 parts of alkali activator, 1-6 parts of foaming agent and 12-20 parts of water; The lithium slag is the residue after lithium is extracted from spodumene concentrate by sulfuric acid roasting method, and its composition is as follows in weight percentage: SiO2 53-59%, Al2O3 21-24%, SO3 5-9%, CaO 3-6%, Na2O 0.3-1.0%, K2O 0.2-0.5%, Fe2O3 0.8-1.5%; the moisture content of the lithium slag is 10%-25%.

2. The lithium slag-based unfired light ceramsite according to claim 1, characterized in that The fineness of the lithium slag is such that 95% of the slag passes through a 0.3 mm sieve hole and 70% of the slag passes through a 0.075 mm sieve hole.

3. The lithium slag-based unfired light ceramsite according to claim 1, characterized in that The cement is 425 ordinary Portland cement; the effective calcium oxide content of the quicklime is above 90%.

4. The lithium slag-based unfired light ceramsite according to claim 1, characterized in that The alkaline activator is one or more of water glass and sodium hydroxide.

5. The lithium slag-based unfired light ceramsite according to claim 4, characterized in that The water glass modulus is 1.5-3, and the concentration is 3-5%.

6. The lithium slag-based unfired light ceramsite according to claim 1, characterized in that The foaming agent is one or more of sodium bicarbonate and ammonium bicarbonate.

7. The method for preparing the lithium slag-based unfired light ceramsite according to any one of claims 1 to 6, characterized in that: The steps include: S1: Weigh 60-80 parts of lithium slag, 10-20 parts of cement, 8-15 parts of quicklime, 3-8 parts of alkali activator, 1-6 parts of foaming agent and 12-20 parts of water according to the weight ratio and set aside; S2: The cement, quicklime, and foaming agent weighed in step S1 are mixed in a mixer and stirred for 10 to 30 minutes. After the stirring is completed, lithium slag is added and stirred again for 10 to 20 minutes. During the stirring process, water is added to obtain a mixed material; S3: The mixed material is fed into a press and a disc granulator via a conveyor belt to start granulation, and an alkali activator is sprayed at the same time to obtain a ceramsite green body; S4: The ceramsite green body granulated in step S3 is placed in a curing box for curing or natural curing to obtain unfired light ceramsite.

8. The method for preparing lithium slag-based unfired light ceramsite according to claim 7, wherein: In step S3, the rotation speed of the disc granulator is 30-35 rpm, the inclination angle is 50°-60°, and the temperature is 20-40°C; and the particle size of the ceramsite embryo is 5-20 mm.

9. The method for preparing lithium slag-based unfired light ceramsite according to claim 7, wherein: In step S4, the temperature of the curing box is 80-100°C, the humidity is 85-95%, and the curing time is 20-24 hours; the natural curing is curing under natural conditions for 27 days.

10. The method for preparing lithium slag-based unfired light ceramsite according to claim 7, characterized in that: The unfired light ceramsite has a cylinder compressive strength of 6.37-9.41 MPa, a bulk density of 614.6-867.3 kg / m3, and a 24-hour mass water absorption rate of 8.7-11.4%.

11. Use of the lithium slag-based unfired light ceramsite according to any one of claims 1 to 6 in ceramsite wall insulation materials.

Images