CN118878232A - A modified lepidolite slag artificial lightweight aggregate and preparation method thereof - Google Patents

Abstract

The invention discloses a modified lithium mica slag artificial light aggregate and a preparation method thereof, belonging to the technical field of solid waste treatment and resource utilization, comprising the following raw materials in mass percentage, wherein the raw materials include 30-60% lithium slag, 15-20% ground lithium slag, 10-20% siliceous material, 8-10% binder, and also include an activator accounting for 0-0.2% of the total mass of the binder, and water accounting for 3-5% of the total mass of the raw materials and 5-10% of the modifier. The invention utilizes lithium slag produced by lithium mica beneficiation as the main raw material, optimizes the raw material particle grading, mixes the raw materials uniformly, and obtains artificial light aggregate with a bulk density of 900-1200kg/m ³ , a 1h water absorption rate of less than 10%, and a cylinder pressure strength of 4.0-13.0MPa through processes such as water sprinkling and stirring, compacting and granulating, demoulding and curing, and interface modification. The artificial lightweight aggregate prepared by this invention can be used for industrial products such as lightweight bricks, lightweight concrete, lightweight prefabricated components, etc., realizing the resource utilization of lithium mica slag.

Description

A modified lepidolite slag artificial lightweight aggregate and preparation method thereof

Technical Field

The invention belongs to the technical field of solid waste treatment and resource utilization, and specifically relates to a modified lepidolite slag artificial lightweight aggregate and a preparation method thereof.

Background Art

With the rapid development of the lithium battery industry, a large amount of lithium slag is produced during lithium mining and lithium battery production. These lithium slags contain rich elements such as silicon, aluminum, and calcium. Direct disposal not only causes a waste of resources, but also causes serious environmental pollution. Therefore, how to effectively utilize lithium slag and turn waste into treasure has important environmental and economic significance.

In addition to the advantages of ordinary concrete such as firmness, durability, and formability, lightweight aggregate concrete prepared from artificial lightweight aggregate also has the advantage of being lightweight (it can reduce its own weight by 20% to 30% compared to ordinary concrete), and can change its strength, thermal properties and other properties with changes in density. It can be used in building structures, enclosures, thermal insulation, lightweight filling, prefabricated components, floating buildings and other fields.

Summary of the invention

In order to solve the above problems, the present invention adopts the following technical solutions:

A modified lithium mica slag artificial lightweight aggregate comprises the following raw materials in percentage by mass: the raw materials comprise 30-60% lithium slag, 15-20% ground lithium slag, 10-20% siliceous material, and 8-10% binder.

The invention also comprises an activator accounting for 0 to 0.2% of the total mass of the binder, water accounting for 3 to 5% of the total mass of the raw materials, and a modifier accounting for 5 to 10% of the total mass of the raw materials.

Preferably, the particle size of the lithium slag is between 30 and 80 meshes, the water content is less than 15%, and the specific surface area of the ground lithium slag is 450 to 600 m ² /kg.

Preferably, the SiO ₂ content of the siliceous material is greater than 70%.

Preferably, the siliceous material is one or more high-silicon tailings such as copper tailings, tungsten tailings, molybdenum tailings and iron tailings.

Preferably, the binder is one or more of cement, fly ash, mineral powder, quicklime, gypsum and steel slag, and the activator is one or more of triethanolamine, triisopropanolamine, water glass and sodium sulfate.

Preferably, the modifier is one or more of sodium methyl silicate, polymethyltriethoxysilane, polyvinyl alcohol and alkyl phenyl sulfonate.

Preferably, the binder contains cement and/or quicklime, wherein the cement content is ≤40wt% and the quicklime content is ≤20wt%.

The present invention also discloses a method for preparing modified lepidolite slag artificial lightweight aggregate, comprising the following steps:

S1: mixing lithium slag and ground lithium slag evenly according to the proportion, adding a binder, mixing evenly, and finally adding an aqueous solution containing an activator and mixing until evenly mixed to obtain a mixed material;

S2: Weigh the mixed material and granulate it to obtain a ball with a smooth surface;

S3: Pre-curing the balls and then autoclaving them to obtain lightweight aggregates

S4: Atomize the modifier and spray it evenly on the surface of the rotating light aggregate. After standing for 1 to 2 hours, the modified lithium mica slag artificial light aggregate is obtained.

Preferably, in step S2,

The granulation is specifically as follows: the mixture material is placed in a double-roll granulator, the loading pressure is 1.0-3.0 kN, and the loading speed is 50-200 rpm to pass through a die with a particle size of 3-10 mm.

Preferably, in step S3,

Pre-curing is as follows: placing the pellets in a sealed state at 25-30°C for 8-12 hours;

The autoclave curing is specifically as follows: the pre-cured pellets are placed in an autoclave and cured for 12 to 24 hours under curing conditions with a carbon dioxide concentration of 80 to 90%, a pressure of 0.8 to 1.2 MPa, a temperature of 80 to 100° C., and a humidity of 65 to 80%.

Beneficial effects of the present invention:

(1) The present invention effectively utilizes lithium mica slag resources, reduces waste discharge and storage problems, reduces production costs, and complies with the concept of resource recycling.

(2) The modified lepidolite slag artificial lightweight aggregate provided by the present invention has a bulk density of less than 1200 kg/m ³ , a 1h water absorption rate of less than 10%, and a cylinder pressure strength of up to 13.0 MPa.

(3) The surface of the modified lithium mica slag artificial lightweight aggregate of the present invention is specially treated to form a hydrophobic film on the surface thereof, which has a low water absorption rate and can effectively prevent water intrusion and improve durability.

(4) The modified lithium mica slag artificial lightweight aggregate of the present invention is granulated by extrusion, which requires less binder, is easy to adjust parameters, has high production efficiency, and saves energy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a flow chart of the preparation of the modified lepidolite artificial lightweight aggregate according to the present invention.

FIG. 2 is a physical picture of the modified lepidolite artificial lightweight aggregate prepared in Example 1 of the present invention.

FIG3 is a SEM image of the modified lepidolite artificial lightweight aggregate prepared in Example 1 of the present invention.

FIG. 4 is a SEM image of the modified lepidolite artificial lightweight aggregate prepared in Comparative Example 1 of the present invention.

DETAILED DESCRIPTION

The lithium slag used in the embodiment of the present invention is taken from Fengxin County, Jiangxi Province. The chemical composition of the lithium slag and the main raw materials is shown in Table 1. The lithium slag is mainly composed of calcium feldspar, gypsum and quartz, which can be used as a calcium raw material, and the tungsten tailings are mainly composed of quartz, which can be used as a silicon raw material.

Table 1 Chemical composition of raw materials

The lithium slag used in the present invention is directly taken from the manufacturer. Since the lithium slag has the characteristics of coarse particle size and high water content, it is not conducive to sufficient stirring. By utilizing its good grindability, part of the lithium slag can be dried, ground and mixed into the lithium slag to adjust the gradation and facilitate stirring. At the same time, the double-roll extrusion method can make the lithium slag fully contact with other raw materials to produce hydration reaction, further make the aggregate dense and improve the cylinder pressure strength, and reduce the production cost.

Please refer to Figure 1 for the preparation process and Figure 2 for the actual picture of the product.

Embodiment 1:

(1) Weighing raw materials of lithium slag, ground lithium slag, siliceous material and binder in a mass ratio of 50:20:10:20; wherein the siliceous material is tungsten tailings, and the mass ratios of cement, fly ash, mineral powder and quicklime in the binder are 10:3:2:5 respectively; the activator is triethanolamine, and the modifier is sodium methyl silicate;

(2) lithium slag and ground lithium slag are placed in a mixer according to the proportion and stirred for 6 minutes until they are uniformly mixed, fly ash, mineral powder, cement, and quicklime are added in sequence and stirred for 3 minutes until they are uniformly mixed, and finally an aqueous solution containing an activator is added and stirred for 3 minutes until they are uniformly mixed;

(3) Weigh an appropriate amount of the prepared mixed material and add it to a roller granulator, adjust the loading pressure to 3.0 kN, and pass it through a die with a particle size of 5 mm at a loading speed of 100 rpm to obtain a ball with a smooth surface;

(4) The prepared pellets are sealed and pre-cured at 25° C. for 12 h, and then the pre-cured pellets are placed in an autoclave and cured for 24 h under curing conditions of 90 vt% carbon dioxide concentration, 1.0 MPa pressure, 80° C. temperature, and 80% humidity to obtain lightweight aggregate;

(5) The light aggregate is taken out and placed on a turntable, and a 20 wt% sodium methyl silicate solution is atomized and evenly sprayed on the surface of the rotating material ball. After standing for 1 hour, the modified lithium mica slag artificial light aggregate is obtained.

According to tests, the modified lepidolite slag artificial lightweight aggregate prepared in this example has a bulk density of 1180 kg/m ³ , a 1h water absorption rate of 4.6%, and a cylinder pressure strength of 12.8 MPa.

Comparative Example 1:

(1) Weighing raw materials of lithium slag, ground lithium slag, siliceous material and binder in a mass ratio of 45:15:10:30; wherein the siliceous material is tungsten tailings, and the mass ratios of cement, fly ash, mineral powder and quicklime in the binder are 10:3:2:5 respectively; the activator is triethanolamine, and the modifier is sodium methyl silicate;

(2) lithium slag and ground lithium slag are placed in a mixer according to the proportion and stirred for 6 minutes until they are uniformly mixed, fly ash, mineral powder, cement, and quicklime are added in sequence and stirred for 3 minutes until they are uniformly mixed, and finally an aqueous solution containing an activator is added and stirred for 3 minutes until they are uniformly mixed;

(3) Weigh an appropriate amount of the prepared mixed material and add it to a granulating disc machine and rotate it at 60 rpm until a smooth ball with a particle size of about 5 mm is formed;

(4) The prepared pellets are sealed and pre-cured at 25° C. for 12 h, and then the pre-cured pellets are placed in an autoclave and cured for 24 h under curing conditions of 90 vt% carbon dioxide concentration, 1.0 MPa pressure, 80° C. temperature, and 80% humidity to obtain lightweight aggregate;

(5) The light aggregate is taken out and placed on a turntable, and a 20 wt% sodium methyl silicate solution is atomized and evenly sprayed on the surface of the rotating material ball. After standing for 1 hour, the modified lithium mica slag artificial light aggregate is obtained.

According to tests, the modified lepidolite slag artificial lightweight aggregate prepared in this example has a bulk density of 920 kg/m ³ , a 1h water absorption rate of 8.1%, and a cylinder pressure strength of 6.2 MPa.

Comparative Example 2:

(1) Weighing raw materials with a mass ratio of lithium slag, siliceous material and binder of 70:10:20; wherein the siliceous material is tungsten tailings, and the mass ratios of cement, fly ash, mineral powder and quicklime in the binder are 10:3:2:5 respectively; the activator is triethanolamine, and the modifier is sodium methyl silicate;

(2) according to the proportion, the lithium slag is placed in a mixer and stirred for 6 minutes, fly ash, mineral powder, cement, and quicklime are added in sequence and mixed and stirred for 3 minutes until uniform, and finally, an aqueous solution containing an activator is added and stirred for 3 minutes until uniform;

(3) Weigh an appropriate amount of the prepared mixed material and add it to a roller granulator, adjust the loading pressure to 3.0 kN, and pass it through a die with a particle size of 5 mm at a loading speed of 100 rpm to obtain a ball with a smooth surface;

(4) The prepared pellets are sealed and pre-cured at 25° C. for 12 h, and then the pre-cured pellets are placed in an autoclave and cured for 24 h under curing conditions of 90 vt% carbon dioxide concentration, 1.0 MPa pressure, 80° C. temperature, and 80% humidity to obtain lightweight aggregate;

(5) The light aggregate is taken out and placed on a turntable, and a 20 wt% sodium methyl silicate solution is atomized and evenly sprayed on the surface of the rotating material ball. After standing for 1 hour, the modified lithium mica slag artificial light aggregate is obtained.

According to tests, the modified lepidolite slag artificial lightweight aggregate prepared in this example has a bulk density of 1020 kg/m ³ , a 1h water absorption rate of 6.3%, and a cylinder pressure strength of 8.8 MPa.

Comparative Example 3:

(1) Weighing raw materials of lithium slag, ground lithium slag, siliceous material and binder in a mass ratio of 50:20:10:20; wherein the siliceous material is tungsten tailings, and the mass ratios of cement, fly ash, mineral powder and quicklime in the binder are 10:3:2:5 respectively; the activator is triethanolamine, and the modifier is sodium methyl silicate;

(2) lithium slag and ground lithium slag are placed in a mixer according to the proportion and stirred for 6 minutes until they are uniformly mixed, fly ash, mineral powder, cement, and quicklime are added in sequence and stirred for 3 minutes until they are uniformly mixed, and finally an aqueous solution containing an activator is added and stirred for 3 minutes until they are uniformly mixed;

(3) Weigh an appropriate amount of the prepared mixed material and add it to a roller granulator, adjust the loading pressure to 3.0 kN, and pass it through a die with a particle size of 5 mm at a loading speed of 100 rpm to obtain a ball with a smooth surface;

(4) The prepared pellets are sealed and pre-cured at 25°C for 12 hours, and then the pre-cured pellets are placed in an autoclave and cured for 24 hours at a carbon dioxide concentration of 90vt%, a pressure of 1.0MPa, a temperature of 80°C, and a humidity of 80% to obtain artificial lightweight aggregate.

According to tests, the modified lepidolite slag artificial lightweight aggregate prepared in this example has a bulk density of 1130 kg/m ³ , a 1h water absorption rate of 9.3%, and a cylinder pressure strength of 12.2 MPa.

Embodiment 2:

(1) Weighing raw materials of lithium slag, ground lithium slag, siliceous material and binder in a mass ratio of 50:20:10:20; wherein the siliceous material is tungsten tailings, and the mass ratios of cement, fly ash, mineral powder and quicklime in the binder are 10:3:2:5 respectively; the activator is triethanolamine, and the modifier is sodium methyl silicate;

(2) lithium slag and ground lithium slag are placed in a mixer according to the proportion and stirred for 6 minutes until they are uniformly mixed, fly ash, mineral powder, cement, and quicklime are added in sequence and stirred for 3 minutes until they are uniformly mixed, and finally an aqueous solution containing an activator is added and stirred for 3 minutes until they are uniformly mixed;

(3) Weigh an appropriate amount of the prepared mixed material and add it to a roller granulator, adjust the loading pressure to 1.0 kN, and pass it through a die with a particle size of 5 mm at a loading speed of 50 rpm to obtain a ball with a smooth surface;

(4) The prepared pellets are sealed and pre-cured at 25° C. for 12 h, and then the pre-cured pellets are placed in an autoclave and cured for 24 h under curing conditions of 90 vt% carbon dioxide concentration, 1.0 MPa pressure, 80° C. temperature, and 80% humidity to obtain lightweight aggregate;

(5) The light aggregate is taken out and placed on a turntable, and a 20 wt% sodium methyl silicate solution is atomized and evenly sprayed on the surface of the rotating material ball. After standing for 1 hour, the modified lithium mica slag artificial light aggregate is obtained.

According to tests, the modified lepidolite slag artificial lightweight aggregate prepared in this example has a bulk density of 910 kg/m ³ , a 1h water absorption rate of 5.3%, and a cylinder pressure strength of 7.7 MPa.

Embodiment 3:

(1) Weighing raw materials with a mass ratio of 60:20:10:10 among lithium slag, ground lithium slag, siliceous material and binder; wherein the siliceous material is tungsten tailings, and the mass ratios of cement, fly ash, mineral powder and quicklime in the binder are 8:5:3:4 respectively; the activator is triethanolamine, and the modifier is sodium methyl silicate;

(2) lithium slag and ground lithium slag are placed in a mixer according to the proportion and stirred for 6 minutes until they are uniformly mixed, fly ash, mineral powder, cement, and quicklime are added in sequence and stirred for 3 minutes until they are uniformly mixed, and finally an aqueous solution containing an activator is added and stirred for 3 minutes until they are uniformly mixed;

(3) Weigh an appropriate amount of the prepared mixed material and add it to a roller granulator, adjust the loading pressure to 3.0 kN, and pass it through a die with a particle size of 5 mm at a loading speed of 100 rpm to obtain a ball with a smooth surface;

(4) The prepared pellets are sealed and pre-cured at 25° C. for 12 h, and then the pre-cured pellets are placed in an autoclave and cured for 24 h under curing conditions of 90 vt% carbon dioxide concentration, 1.0 MPa pressure, 80° C. temperature, and 80% humidity to obtain lightweight aggregate;

(5) The light aggregate is taken out and placed on a turntable, and a 20 wt% sodium methyl silicate solution is atomized and evenly sprayed on the surface of the rotating material ball. After standing for 1 hour, the modified lithium mica slag artificial light aggregate is obtained.

According to tests, the modified lepidolite slag artificial lightweight aggregate prepared in this example has a bulk density of 1160 kg/m ³ , a 1h water absorption rate of 4.9%, and a cylinder pressure strength of 10.2 MPa.

By comparing the above Example 1 and Comparative Example 1, it can be seen that the present invention improves the granulation method to extrusion granulation, so that the lithium slag can fully contact with other raw materials for hydration reaction, thereby significantly improving the performance of the lightweight aggregate with less binder dosage.

At the same time, the modified lithium mica artificial light aggregate prepared in Example 1 and Comparative Example 1 was scanned by electron microscope, and the results are shown in Figures 3 and 4. As can be seen from Figure 3, the interior of the light aggregate prepared in Example 1 is a relatively dense whole with fewer pores and abundant hydration products; the light aggregate prepared in Comparative Example 1 has more pores inside and of different sizes, and some fly ash particles do not participate in hydration; it also further illustrates that the present invention improves the granulation method into extrusion granulation, so that the lithium slag can fully contact with other raw materials for hydration reaction, thereby significantly improving the performance of the light aggregate with less binder dosage.

By comparing Example 1 and Comparative Example 2, it can be seen that since lithium slag has the characteristics of coarse particle size and high water content, it is not conducive to sufficient stirring. By utilizing its good grindability, part of the lithium slag can be dried and ground and mixed into the lithium slag to adjust the grading and facilitate stirring, thereby improving the performance of the lightweight aggregate.

By comparing Example 1 and Comparative Example 3, it can be seen that the present invention sprays a modifier on the surface of the light aggregate after curing to form a hydrophobic film on the surface to prevent water intrusion and greatly reduce the water absorption rate.

By comparing Examples 1-3, it can be seen that the present invention adopts appropriate loading pressure to ensure the performance of the lightweight aggregate, while the pressure adopted in Comparative Example 4 is too small, resulting in insufficient contact, which affects the hydration reaction of the lightweight aggregate and causes poor performance.

The above is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. It is not necessary and impossible to list all implementation methods here, so any slight modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention still belongs to the scope of the technical solution of the present invention.

Claims (10)

1. A modified lithium mica slag artificial lightweight aggregate, characterized in that it comprises the following raw materials in percentage by mass, wherein the raw materials comprise 30-60% lithium slag, 15-20% ground lithium slag, 10-20% siliceous material, and 8-10% binder, The invention also comprises an activator accounting for 0 to 0.2% of the total mass of the binder, water accounting for 3 to 5% of the total mass of the raw materials, and a modifier accounting for 5 to 10% of the total mass of the raw materials. 2. The modified lithium mica slag artificial lightweight aggregate according to claim 1, characterized in that the particle size of the lithium slag is between 30 and 80 meshes, the moisture content is less than 15%, and the specific surface area of the ground lithium slag is 450 to 600 ^m2 /kg. 3. The modified lepidolite slag artificial lightweight aggregate according to claim 1, characterized in that the _SiO2 content of the siliceous material is greater than 70%. 4. The modified lepidolite slag artificial lightweight aggregate according to claim 1, characterized in that the siliceous material is one or more of high-silicon tailings such as copper tailings, tungsten tailings, molybdenum tailings and iron tailings. 5. The modified lepidolite slag artificial lightweight aggregate according to claim 1, characterized in that the binding agent is one or more of cement, fly ash, mineral powder, quicklime, gypsum and steel slag, and the activator is one or more of triethanolamine, triisopropanolamine, water glass and sodium sulfate. 6. The modified lepidolite slag artificial lightweight aggregate according to claim 1, characterized in that the modifier is one or more of sodium methyl silicate, polymethyltriethoxysilane, polyvinyl alcohol and alkyl phenyl sulfonate. 7. modified lepidolite slag artificial lightweight aggregate according to claim 4 is characterized in that, contains cement and/or quicklime in the described binding agent, wherein cement content≤40wt%, quicklime content≤20wt%. 8. The method for preparing the modified lepidolite slag artificial lightweight aggregate according to any one of claims 1 to 7, characterized in that it comprises the following steps: S1: mixing lithium slag and ground lithium slag evenly according to the proportion, adding a binder, mixing evenly, and finally adding an aqueous solution containing an activator and mixing until evenly mixed to obtain a mixed material; S2: Weigh the mixed material and granulate it to obtain a ball with a smooth surface; S3: pre-curing the material balls and then autoclaving them to obtain lightweight aggregates; S4: Atomize the modifier and spray it evenly on the surface of the rotating light aggregate. After standing for 1 to 2 hours, the modified lithium mica slag artificial light aggregate is obtained. 9. The preparation method according to claim 8, characterized in that in step S2, The granulation is specifically as follows: the mixture material is placed in a double-roll granulator, the loading pressure is 1.0-3.0 kN, and the loading speed is 50-200 rpm to pass through a die with a particle size of 3-10 mm. 10. The preparation method according to claim 8, characterized in that in step S3, Pre-curing is as follows: placing the pellets in a sealed state at 25-30°C for 8-12 hours; The autoclave curing is specifically as follows: the pre-cured pellets are placed in an autoclave and cured for 12 to 24 hours under curing conditions with a carbon dioxide concentration of 80 to 90%, a pressure of 0.8 to 1.2 MPa, a temperature of 80 to 100° C., and a humidity of 65 to 80%.