CN112830698B - Method for preparing non-burning geopolymer material by acid thermal excitation of spodumene flotation tailings - Google Patents

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 non-burning geopolymer material by acid thermal excitation of spodumene flotation tailings

technical field

The invention belongs to the technical field of industrial solid waste recycling for preparing non-burning materials, and in particular relates to a method for preparing non-burning geopolymer materials by using spodumene flotation tailings acid thermal excitation.

Background technique

With the development of the industrial society, the environmental problems brought about by the development of a large number of resources have become increasingly prominent. How to properly handle solid waste has become a hot issue in today's society. Due to its own characteristics, flotation tailings are a special solid waste among solid wastes. , there are problems of huge output, complex pollution problems, and low utilization rate. How to recycle flotation tailings and improve their comprehensive utilization rate has become an urgent problem to be solved. Using industrial solid waste tailings to prepare related materials is an important way to deal with industrial solid waste. Among them, most of the research is to prepare high value-added ceramic materials, glass-ceramic or other structural ceramic materials by high temperature sintering, but there are problems such as high energy consumption and low demand. Therefore, it is of great significance to prepare materials in a way without burning and to improve the utilization rate of tailings as much as possible.

In the field of geopolymers, there are many studies on the preparation of geopolymers by alkali excitation, and there are few reports on acid excitation. How to use acid-thermal excitation to prepare geopolymer materials has become an urgent technical problem to be solved.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the above-mentioned technical problems, and provide a method for preparing a non-burning geopolymer material by using spodumene flotation tailings acid thermal excitation. The invention not only makes full use of the characteristics of tailings, greatly improves the mechanical properties of the traditional single metakaolin excitation material, but also reduces the cracking phenomenon in the excitation process. In the present invention, the preparation conditions and maintenance conditions of the geopolymer are researched and optimized through a large number of experiments, and have great significance in the aspects of environmental protection and economic development.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows: a method for preparing a non-burning geopolymer material by utilizing the acid thermal excitation of spodumene flotation tailings, comprising the following steps:

(1) respectively take by weight 65～85% spodumene flotation tailings and 15～35% metakaolin as raw materials;

(2) adding a phosphoric acid solution with a concentration of 30 to 60% to the resultant of step (1), and stirring to thin mud;

(3) sealing by wrapping the plastic wrap after carrying out the normal pressure injection molding of the result of the step (2);

(4) Put the product obtained in step (3) into a heating device for heating and excitation for 1-2 days, and the heating temperature range is 40-80°C.

(5) demoulding the polymer after the excitation in step (4), and sealing it again with plastic wrap, and then placing it in a cement curing box for standard curing. Geopolymer material.

The above method provided by the present invention realizes the successful preparation of a non-fired geopolymer material with excellent mechanical properties under the conditions of no firing and no pressure molding, which greatly saves the energy of high-temperature sintering for preparing the material, and overcomes the problem that the material is easy to deformation problem. In this method, metakaolin is selected as the excitation raw material, and tailings and fine-grained standard sand are selected to improve the flexural strength and compressive strength of the geopolymer. The process conditions and raw material dosage in each step are strictly controlled. The optimized process obtained after a lot of exploration can maximize the quality of the obtained non-burning geopolymer. The invention also saves the raw material ball milling process and the pressure forming process, saves energy, and the utilization rate of the spodumene flotation tailings is as high as 85%.

The present invention realizes the significant enhancement of the mechanical properties of the geopolymer by adding the mixture of tailings and fine-grained standard sand, and the utilization rate of tailings is high. This provides a new reference direction for tailings treatment, which is of great significance in the fields of environmental protection and building materials.

Further, the spodumene flotation tailings described in step (1) are tailings after lithium production enterprises extract lithium through a flotation process or tailings after a leaching process.

Further, the strip mold used in the injection molding in step (3) is a six-unit mold with a size of 10×10×60 mm, and the square shape used is a single cylindrical mold with a size of 40×40×40 mm.

Further, the heating device in step (4) is an electric heating blast drying oven.

Compared with the prior art, the beneficial effects of the present invention are as follows:

(1) Using spodumene flotation tailings as the main raw material to prepare non-burning geopolymer materials, which solves the problem of difficult disposal of spodumene flotation tailings, of which spodumene flotation tailings account for up to 65% of the total weight. ～85%, can realize large-scale resource utilization of industrial solid waste, with obvious social, environmental and economic benefits.

(2) The present invention breaks through the technical problem that the material prepared by using tailings must be press-molded and sintered at high temperature. In view of this difficulty, the present invention successfully prepares the ground with excellent mechanical properties under the condition of no burning by means of acid heat excitation. Polymer material, greatly reducing energy consumption.

(3) The present invention breaks through the technical problem of low mechanical properties of pure metakaolin polymer materials, and greatly improves its mechanical properties by adding a mixture of fine-grained quartz sand and flotation tailings.

(4) The particle size of the spodumene flotation tailings used is relatively fine, supplemented by a cheap mineral metakaolin with a finer particle size as the binding material, and the particle size characteristics of the spodumene flotation tailings are fully utilized; the present invention By using wet injection molding instead of traditional pressure molding, the energy consumption is low, and its mechanical properties are greatly improved by adding tailings or fine-grained quartz sand, which has high economic, social and environmental benefits.

(5) After adding tailings and fine-grained standard sand, the geopolymer product not only has excellent mechanical properties, but also effectively reduces its cracking phenomenon. It has high economic, social and environmental benefits in the field of solid waste treatment and building decoration materials.

Description of drawings

The left picture in Figure 1 is the picture of the sample covered with plastic wrap after injection molding, which is heated and excited in an oven, and the right picture is the sample after demoulding, which is wrapped and sealed with plastic wrap again and then placed in a curing box for curing; The size of the strip sample is 10×10×60mm, which is used to test the flexural strength of the sample, and the size of the square sample is 40×40×60mm, which is used to test the compressive strength of the sample.

Figure 2 shows the spodumene flotation tailings non-burning geopolymer material prepared with the formula of No. 123 in Table 2.

Fig. 3 is a picture of the sample when the drying temperature of No. 6 in Table 2 is 80 °C, which has obvious cracking, and reducing the temperature and increasing the amount of tailings added can effectively reduce the cracking.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be described in detail below with reference to the examples. It is necessary to point out that the following examples are only used to explain and illustrate the present invention, and are not intended to limit the present invention. . Some non-essential improvements and adjustments made by those skilled in the art based on the above-mentioned contents of the invention still belong to the protection scope of the present invention.

Example 1

According to each raw material formula in the following table 1, the raw materials are weighed to prepare the non-burning geopolymer material. Molded by atmospheric pressure injection and sealed with plastic wrap. It was put into a heating device and heated for 1 to 2 days, and the heating temperature ranged from 40 to 80°C. After the excitation is completed, the polymer is demolded, sealed with plastic wrap again, and then placed in a cement curing box for standard curing at a curing temperature of 20° C. and a humidity of 95%.

The flexural strength and compressive strength of the above-mentioned non-fired products are tested. For the specific test method, refer to GB/T4741-1999 Test Method for Flexural Strength of Ceramic Materials and GB/T4740-1999 Test Method for Compressive Strength of Ceramic Materials. Test results As shown in Table 1.

Table 1

Comparative Example 1

According to the preparation method of Example 1, standard sands with different particle sizes were sorted by sieving (20 mesh and 32 mesh sieves), and divided into coarse particle size (>0.85mm), medium particle size (0.5-0.85mm) and fine particle size (< 0.5mm). Its mass ratio to metakaolin is 3:1, that is, 300g of standard sand and 100g of metakaolin. The specific flexural strength and compressive strength test results are shown in Table 2.

Table 2

Comparative Example 2

According to the method of Example 1, only using metakaolin as raw material, the strength of the sample is significantly lower than that of the sample after adding tailings and standard sand, while the strength of the sample after only adding spodumene flotation tailings is significantly improved, but still lower than The mixed samples of tailings and standard sand under the same conditions, the specific results are shown in Table 2.

Comparative Example 3

According to the method of Example 1, when the heating and excitation temperature is low (<30°C), the strength of the sample is very low, and the excitation cannot be completed. When the heating temperature is high (>70°C), the sample reacts violently and cracks seriously. It is not conducive to the application of this process.

Comparative Example 4

According to the method of Example 1, when the phosphoric acid concentration is low (<20%), the sample strength is low (compressive strength <20MPa), and when the phosphoric acid concentration is high (>70%), the sample has excellent mechanical properties , but the surface softened obviously after many days, which is not conducive to the application of this process. The specific formulas are shown in Nos. 8 and 9 in Table 2.

Comparative Example 5

According to the method of Example 1, the formula of the sample No. 3 in Table 1 is used, except that the film is not covered during the heating and excitation process, and the intensity is very low when directly heated and excited. The mechanical properties of the samples prepared with the same formula and different curing conditions during the curing process are all lower than those in the curing box covered with film and sealed, and this curing method has a positive effect on the later mechanical properties enhancement. The specific test results are shown in Table 3.

table 3

Comparative Example 6

According to the method of Example 1, after replacing metakaolin with kaolin or fly ash, the sample could not be successfully excited and had almost no mechanical properties.

Comparative Example 7

According to the method of Example 1, the formula No. 3 in Table 1 is used, except that phosphoric acid is replaced with water glass solutions of different modulus, and the geopolymer is prepared by means of alkali excitation, and the test results of its mechanical properties are all lower than the same conditions. Butyric acid excites the prepared geopolymer.

Claims (4)

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;

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

(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.

Images