CN112830698B

CN112830698B - Method for preparing baking-free geopolymer material by utilizing spodumene flotation tailings acid-thermal excitation

Info

Publication number: CN112830698B
Application number: CN202110342583.6A
Authority: CN
Inventors: 徐龙华; 杨洁; 巫侯琴; 卢忠远
Original assignee: Southwest University of Science and Technology
Current assignee: Southwest University of Science and Technology
Priority date: 2021-03-30
Filing date: 2021-03-30
Publication date: 2022-04-26
Anticipated expiration: 2041-03-30
Also published as: CN112830698A

Abstract

The invention provides a method for preparing a high-strength baking-free geopolymer material by utilizing acid-thermal excitation of spodumene flotation tailings, which comprises the following steps of: (1) weighing 65-85% of spodumene flotation tailings and 15-35% of metakaolin according to weight percentage; (2) adding a phosphoric acid solution with the concentration of 30-60%, and stirring to be in a slurry shape, wherein the adding amount of the phosphoric acid solution is 15-55% of the total weight of the solid; (3) performing normal pressure injection molding on the product obtained in the step (2); (4) and (4) coating the film on the substance obtained in the step (3), putting the coated film into a heating device for heating and excitation, taking out the coated film after reaction, sealing the coated film by using a preservative film again, and curing the coated film in a curing box to obtain the sintering-free geopolymer material of the spodumene flotation tailings. The method not only fully utilizes the characteristics of the tailings, greatly improves the mechanical property of the traditional single metakaolin excited material, but also can reduce the cracking phenomenon in the excitation process, and has important significance in the aspects of environmental protection and economic development.

Description

Method for preparing baking-free geopolymer material by utilizing spodumene flotation tailings acid-thermal excitation

Technical Field

The invention belongs to the technical field of preparing non-fired materials by using industrial solid waste resources, and particularly relates to a method for preparing a non-fired geopolymer material by utilizing acid-heat excitation of spodumene flotation tailings.

Background

With the development of industrial society, environmental problems brought by the development of a large number of resources are increasingly prominent, how to properly treat solid wastes becomes a hot problem in the current society, flotation tailings are used as special solid wastes in the solid wastes due to the characteristics of the flotation tailings, and the problems of huge yield, complex pollution problem and low utilization rate exist. How to recycle the flotation tailings and improve the comprehensive utilization rate of the flotation tailings becomes a problem to be solved urgently. The preparation of related materials by utilizing industrial solid waste tailings is an important way for treating industrial solid waste. The research is more in the preparation of ceramic materials with high added values, microcrystalline glass or other structural ceramic materials through high-temperature sintering, but the problems of high energy consumption, low demand and the like exist. Therefore, the material is prepared in a baking-free mode, and the method has important significance for improving the utilization rate of tailings as much as possible.

In the field of geopolymers, the preparation of geopolymers by alkali excitation is more studied and the related reports of acid excitation are less. How to prepare geopolymer materials by acid thermal excitation becomes a technical problem to be solved urgently.

Disclosure of Invention

The invention aims to solve the technical problems and provides a method for preparing a baking-free geopolymer material by utilizing acid-heat excitation of spodumene flotation tailings. The invention not only makes full use of the characteristics of the tailings, greatly improves the mechanical property of the traditional single metakaolin excited material, but also can reduce the cracking phenomenon in the excitation process. The preparation condition and the maintenance condition of the geopolymer are researched and optimized through a large number of experiments, and the method has important significance in the aspects of environmental protection and economic development.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows: a method for preparing a baking-free geopolymer material by utilizing acid-thermal excitation of spodumene flotation tailings comprises the following steps:

(1) respectively weighing 65-85% of spodumene flotation tailings and 15-35% of metakaolin as raw materials according to weight percentage;

(2) adding a phosphoric acid solution with the concentration of 30-60% into the product obtained in the step (1), and stirring the mixture to be in a sludge state;

(3) performing normal pressure injection molding on the product obtained in the step (2), and then sealing by winding a preservative film;

(4) and (4) putting the product obtained in the step (3) into a heating device, and heating and exciting for 1-2 days at the heating temperature of 40-80 ℃.

(5) And (4) demolding the polymer after the excitation in the step (4) is finished, sealing the polymer by using a preservative film again, and then placing the polymer in a cement curing box for standard curing, wherein the curing temperature is 20 ℃, and the humidity is 95%, so that the baking-free geopolymer material is obtained.

The method provided by the invention realizes the successful preparation of the baking-free geopolymer material with excellent mechanical property under the conditions of baking-free and no need of compression molding, greatly saves the energy for preparing the material by high-temperature sintering, and overcomes the problem that the material is easy to deform. The method selects metakaolin as an excitation raw material, selects tailings and fine-grain standard sand for compounding so as to improve the flexural strength and compressive strength of the geopolymer, strictly controls the process conditions and the raw material dosage in each step, and can maximally ensure the quality of the obtained burning-free geopolymer through an optimized process obtained after a large amount of groping. The invention also saves the ball milling process and the pressure forming process of the raw materials, saves energy and has the utilization rate of spodumene flotation tailings as high as 85 percent.

The method of the invention realizes the obvious enhancement of the mechanical property of the geopolymer by adding the mixture of the tailings and the fine standard sand, and the utilization rate of the tailings is high. The method provides a new reference direction for tailing treatment and has important significance in the fields of environmental protection and building materials.

Further, the spodumene flotation tailings obtained in the step (1) are tailings obtained after lithium is extracted by a flotation process or tailings obtained after a leaching process in lithium production enterprises.

Further, the injection molding in the step (3) uses a six-part mold having a size of 10 × 10 × 60mm and a single cylindrical mold having a square pattern of 40 × 40 × 40 mm.

Further, the heating device in the step (4) is an electric heating air blowing drying box.

Compared with the prior art, the invention has the following beneficial effects:

(1) the non-fired geopolymer material is prepared by using tailings obtained after spodumene flotation as a main raw material, so that the problem of difficulty in treatment of the spodumene flotation tailings is solved, wherein the spodumene flotation tailings account for 65-85% of the total weight, the large-scale resource utilization of industrial solid wastes can be realized, and the method has obvious social benefits, environmental benefits and economic benefits.

(2) The invention breaks through the technical problem that the preparation of the material by utilizing the tailings must be pressed and molded and sintered at high temperature, and aiming at the difficulty, the invention successfully prepares the geopolymer material with excellent chemical properties under the condition of no firing by an acid-heat excitation mode, thereby greatly reducing the energy consumption.

(3) The invention breaks through the technical problem of lower mechanical property of pure metakaolin geopolymer material, and greatly improves the mechanical property by adding the mixture of fine quartz sand and flotation tailings.

(4) The spodumene flotation tailings have fine granularity, and a cheap mineral metakaolin with finer granularity is used as a binding material, so that the granularity characteristic of the spodumene flotation tailings is fully utilized; the invention replaces the traditional pressure molding by adopting the wet injection molding, has low energy consumption, greatly improves the mechanical property by adding the tailings or the fine quartz sand, and has very high economic, social and environmental benefits.

(5) The geopolymer product added with the tailings and the fine standard sand has excellent mechanical properties, effectively reduces the cracking phenomenon, can be applied to the fields of baking-free bricks, geopolymer, hazardous waste solidification, industrial solid waste treatment, building decoration materials and the like, and has high economic, social and environmental benefits.

Drawings

In FIG. 1, the left image is a diagram of a sample covered with a preservative film after injection molding, the sample is placed in an oven for heating and excitation, and the right image is a diagram of a sample after demolding, and the sample is placed in a curing box for curing after being wrapped and sealed by the preservative film again; the specification of the strip-shaped sample is 10 multiplied by 60mm and is used for testing the breaking strength of the sample, and the specification of the square-shaped sample is 40 multiplied by 60mm and is used for testing the compression strength of the sample.

FIG. 2 is a non-fired geopolymer material of spodumene flotation tailings prepared with the formulation number 123 in Table 2.

FIG. 3 is a sample diagram of Table 2 with number 6 at 80 ℃ drying temperature, which shows obvious cracking, and cracking can be effectively reduced by lowering the temperature and increasing the addition amount of tailings.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is described in detail below with reference to the following embodiments, and it should be noted that the following embodiments are only for explaining and illustrating the present invention and are not intended to limit the present invention. The invention is not limited to the embodiments described above, but rather, may be modified within the scope of the invention.

Example 1

The raw materials are weighed according to the raw material formula in the following table 1 to prepare the baking-free geopolymer material, and the preparation method comprises the following steps: mixing the raw materials according to the formula, adding a phosphoric acid solution with the concentration of 40-60%, stirring the mixture to be in a slurry shape, then molding the mixture by normal pressure injection molding, and sealing the molded mixture by a preservative film. Putting the mixture into a heating device for heating and excitation for 1-2 days, wherein the heating temperature range is 40-80 ℃. And (3) demolding the polymer after excitation is finished, sealing the polymer by using a preservative film again, and then placing the polymer in a cement curing box for standard curing, wherein the curing temperature is 20 ℃ and the humidity is 95%.

The flexural strength and the compressive strength of the obtained non-fired product are tested, the specific test method refers to the flexural strength test method of the ceramic material GB/T4741-1999 and the compressive strength test method of the ceramic material GB/T4740-1999, and the test results are shown in Table 1.

TABLE 1

Comparative example 1

According to the preparation method of the example 1, standard sands with different particle sizes are sorted by sieving (20 meshes and 32 meshes), and are divided into coarse particle sizes (>0.85mm), medium particle sizes (0.5-0.85 mm) and fine particle sizes (<0.5 mm). The mass ratio of the metakaolin to the metakaolin is 3: the results of the specific flexural and compressive strength tests are shown in Table 2 for 1, i.e., 300g of standard sand, 100g of metakaolin.

TABLE 2

Comparative example 2

According to the method of example 1, only metakaolin is used as a raw material, the strength of the sample is obviously lower than that of the sample after tailings and standard sand are added, the strength of the sample after only spodumene flotation tailings is obviously improved, but still lower than that of the mixed sample of the tailings and the standard sand under the same conditions, and the specific results are shown in table 2.

Comparative example 3

According to the method of example 1, when the heating excitation temperature is low (<30 ℃), the strength of the sample is very low, the excitation cannot be completed, and when the heating temperature is high (>70 ℃), the reaction of the sample is severe, the cracking is serious, and the application of the process is not facilitated.

Comparative example 4

According to the method of example 1, when the concentration of phosphoric acid is low (< 20%), the strength of the sample is low (<20 MPa), and when the concentration of phosphoric acid is high (> 70%), the mechanical properties of the sample are excellent, but the surface of the sample is obviously softened after a plurality of days, which is not favorable for the application of the process. The specific formulations are shown in

numbers

8 and 9 in table 2.

Comparative example 5

The method of example 1 was followed using the formulation of sample No. 3 in table 1, except that the intensity was very low when the film was directly heated without being coated during the heating excitation. The sample prepared by adopting the same formula and different curing conditions in the curing process has mechanical properties lower than that of a coated film sealed curing in a curing box, and the curing mode has a positive effect on the later-stage mechanical property enhancement. Specific test results are shown in table 3.

TABLE 3

Comparative example 6

Following the procedure of example 1, the sample failed to successfully excite and had almost no mechanical properties after replacing metakaolin with kaolin or fly ash.

Comparative example 7

The method of example 1 was followed using the formulation numbered 3 in Table 1, except that the base-activated geopolymer was prepared by replacing phosphoric acid with water glass solutions of different moduli, and the mechanical properties of the geopolymer were all lower than those of the acid-activated geopolymer prepared under the same conditions.

Claims

1. A method for preparing a baking-free geopolymer material by utilizing acid-thermal excitation of spodumene flotation tailings is characterized by comprising the following steps:

(1) respectively weighing 52.5-67.5% of spodumene flotation tailings, 7.5-22.5% of fine standard sand and 25% of metakaolin as raw materials in percentage by weight;

(2) adding a phosphoric acid solution with the mass concentration of 51-60% into the raw materials in the step (1), and stirring to be in a sludge state;

(4) putting the product obtained in the step (3) into a heating device, and heating and exciting for 1-2 days at 50-60 ℃;

(5) and (4) demolding the polymer excited in the step (4), sealing the polymer by using a preservative film again, and then placing the polymer in a cement curing box for standard curing, wherein the curing temperature is maintained at 20 ℃, and the humidity is 95%, so that the baking-free geopolymer material is obtained.

2. The method according to claim 1, wherein the spodumene flotation tailings obtained in the step (1) are tailings obtained after lithium production enterprises extract lithium through a flotation process.

3. The method as claimed in claim 1, wherein the injection molding in the step (3) uses a six-up mold having a size of 10 x 60mm as a bar-shaped mold, and a single cylindrical mold having a square pattern of 40 x 40mm as a square pattern.

4. The method of claim 1, wherein the heating device in step (4) is an electrically heated forced air drying oven.