Preparation method of red mud-based bagasse fiber reinforced composite gel material

Abstract

The invention relates to a preparation method of a red mud-based bagasse fiber reinforced composite gel material, which comprises the following steps: (1) drying red mud at 100 DEG C for 24 hours, grinding in a ball mill for 3 hours, and screening out powder with the particle size of 70-120 meshes for later use; (2) washing bagasse with water to remove impurities, drying the bagasse in a drying box at 50 DEG C for 24 hours, crushing the bagasse with a ball mill, sieving the crushed bagasse with a 100-mesh sieve, collecting lower-layer powder, and performing pretreatment on the bagasse powder and a dimethyl sulfoxide (DMSO) / LiCl solution; and (3) mixing the prepared bagasse with quantitative red mud and sodium silicate, adding the mixed solution into a reaction kettle, and reacting for 120 minutes under the conditions of 220 DEG C and 300 r / min. After the reaction is completed, carrying out solid-liquid separation, retaining supernate by using a sample tube, and briquetting filter residues; and (4) performing moisture detection, compressive strength detection, pore detection and 7-day maintenance detection on the pressed raw blocks. The utilization rate of the red mud is 100%, the utilization rate of the bagasse is 100%, the total porosity is about 20%, the proportion of macropores is 1%-5%, the proportion of micropores is 90% or above, and the compressive strength reaches 5 MPa or above within 7 days.

Description

Technical Field

[0001] The invention relates to the field of environmental protection, and in particular to a method for comprehensive utilization of red mud and bagasse. Background Art

[0002] Red mud is one of the largest solid wastes discharged during the metal smelting process in my country. According to statistics, the average annual discharge of red mud in my country is 20 million tons to 30 million tons. According to different production methods of alumina, red mud can generally be divided into Bayer red mud, sintering red mud and combined red mud. The alkali content of various types of red mud is 5% to 10%, and the pH after discharge into the water can reach 12 to 13. This type of strong alkaline waste, whether discharged into rivers and seas or infiltrated into the surface and underground, will cause serious pollution of water and soil resources, and occupy a large amount of land resources.

[0003] In order to achieve efficient utilization of red mud and extraction of valuable elements, my country's aluminum industry has carried out a lot of research and development work. For example, Ji Hongbo et al. invented "A low-carbon, low-temperature permeable concrete and its preparation method, application number: CN202410431468.X", which contains 100 parts of concrete material particles, 800-900 parts of soil, 40-60 parts of water, 5-10 parts of low-carbon cementitious materials, and concrete particles including: 55%-70% coal gangue, 5%-10% slag, 10%-25% red mud, and 5%-15% alkali activator. Compared with traditional concrete, it has good water permeability, allows rainwater to quickly penetrate into the ground, reduces surface water accumulation and pressure on drainage systems, helps prevent floods and has better durability; Zhang Wenjie et al. The invention of "A method for resource utilization of laterite nickel ore iron-aluminum slag, application number: CN202410429708.2" involves acid leaching red mud to dissolve at least part of the metal oxides in the red mud, and obtaining leaching slag and a first leaching solution after solid-liquid separation; at least part of the metal oxides include iron oxides, aluminum oxides and scandium oxides; the first leaching solution is mixed with phosphate, and iron phosphate and a second leaching solution are obtained after solid-liquid separation; the mixture of laterite nickel ore iron-aluminum slag and a reducing agent is subjected to reduction roasting to obtain a roasting product; the iron in the roasting product is separated to obtain iron concentrate and aluminum slag containing scandium; the aluminum slag containing scandium is subjected to high-temperature and high-pressure acid leaching reaction with the second leaching solution to obtain alumina and a third leaching solution containing scandium; and the third leaching solution is selectively precipitated with scandium. The method is simple to operate, low in cost, and can efficiently and selectively recover valuable metals iron, aluminum and scandium in laterite nickel ore and red mud, with high economic benefits.

[0004] Similarly, lignocellulose is the most abundant renewable resource on land, mainly composed of cellulose, hemicellulose and lignin. As the main component of lignocellulose, cellulose is a linear polymer composed of repeated glucose units connected by B-1, 4-glycosidic bonds. It acts as the main skeleton in lignocellulose gel and provides mechanical strength and stability for the gel. Hemicellulose is a polymer composed of multiple monosaccharides. Due to the presence of side chains, it is filled in the three-dimensional network of cellulose, which can not only maintain the mechanical strength of the gel, but also provide additional flexibility to the gel, thereby improving the overall bending performance and stretching of the material. Sugarcane is a major agricultural crop produced in tropical and subtropical regions. 80% of the sugar in the global market comes from sugarcane. For every 1,000 tons of sugarcane processed, 270 tons of bagasse will be produced. The cellulose content in bagasse is 32%~45%. In addition, lignin has the characteristics of conjugated structure, aromatic properties and functional groups such as phenolic hydroxyl groups, which makes lignin-containing gels applicable to UV blocking, antibacterial and reduction. It can be seen that the research and development of the utilization of all components of lignocellulose is of great significance to achieving the goal of "same source and same flow, making the best use of resources".

[0005] Therefore, despite the numerous studies on the utilization of red mud in the alumina industry, the stockpiling problem of red mud has not yet been properly solved. When red mud is used as a general industrial raw material, there are problems such as red mud alkalinity, low product prices, and poor returns; the methods of extracting valuable elements separately mostly have problems such as long processing processes, large amounts of wastewater, and tailings that cannot be utilized. The mixed reaction of bagasse and red mud to generate gel materials for use as filling materials will provide the possibility of leaping from the laboratory to the industrial level. Summary of the invention

[0006] In order to better realize the comprehensive utilization of red mud and bagasse, the present invention provides a method for preparing a red mud-based bagasse fiber-reinforced composite gel material, that is, using red mud and bagasse as raw materials, a gel material is generated by high-temperature activation. The technical solution of the present invention is implemented according to the following steps:

[0007] (1) The red mud was dried in a drying oven at 100°C for 24 h, then ground in a ball mill for 3 h, and the powder with a particle size of 70-120 mesh was sieved out for later use;

[0008] (2) After washing to remove impurities such as sand, the bagasse was placed in a 50°C drying oven for 24 h. It was crushed using a ball mill and passed through a 100-mesh sieve. The lower layer of powder was collected. The ball-milled bagasse was pretreated with a dimethyl sulfoxide (DMSO) / Li Cl solution.

[0009] (3) Red mud, water glass and prepared bagasse are mixed to form a mixed solution, which is added into a high-pressure reactor and reacted for 120 min at 220°C and 300 r / min. After the reaction is completed, the obtained product is filtered to separate the solid and liquid. After centrifugation, the supernatant filtrate is retained in a sample tube, and the filter residue is pressed into blocks;

[0010] (4) Take samples of the pressed raw materials and conduct moisture test, compressive strength test, porosity test and 7-day curing test.

[0011] Compared with the prior art, the characteristics and beneficial effects of the present invention are:

[0012] (1) Using bagasse as a material to activate red mud, bagasse itself is also a green resource with excellent properties such as renewable, biodegradable and thermally stable. Pretreated bagasse can provide better performance;

[0013] (2) When red mud and bagasse react in a high-temperature reactor, a small amount of sucrose is attached to the bagasse, which will provide reducing substances under pyrolysis to reduce other metal elements and enrich them in the solution. The mechanical strength and elasticity of the red mud after the reaction are higher. The higher cellulose and slightly higher lignin content in the bagasse can enhance the structure of the red mud. The glass modulus can improve the strength of alkali-activated red mud cementitious materials, mainly because the active SiO2 present in the red mud will enhance the stability of other amorphous phase substances;

[0014] (3) The utilization rate of red mud in the present invention is 100%, and the utilization rate of bagasse is 100%. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the process flow of the present invention DETAILED DESCRIPTION

[0016] The present invention is further described in detail below in conjunction with the embodiments.

[0017] Example 1

[0018] The raw material red mud content is 60%, bagasse content is 40%, and the water glass modulus is 1.25.

[0019] (1) Weigh 300g of red mud and dry it in a drying oven at 100℃ for 24h. After drying, grind it in a ball mill for 3h and sieve out powder with a particle size of 70-120 mesh for later use;

[0020] (2) 200 g of sugarcane bagasse was washed with water to remove impurities such as sand and then dried in a 50°C drying oven for 24 h. It was crushed using a ball mill and passed through a 100-mesh sieve. The lower layer of powder was collected. The ball-milled bagasse was pretreated with a dimethyl sulfoxide (DMSO) / Li Cl solution.

[0021] (3) Mix 300g of red mud, 20% parametric water glass and 200g of the prepared sucrose residue solution to form a mixed solution, add them together into a high-pressure reactor, and react for 120 min at 220°C and 300 r / min. After the reaction is completed, the obtained product is filtered to separate the solid and liquid. After centrifugation, the supernatant filtrate sample tube is retained, and the filter residue is pressed into blocks;

[0022] (4) Samples were taken from the pressed raw materials for moisture testing, compressive strength testing, porosity testing, and 7-day curing testing. After 7 days, the moisture content was 5%, the total porosity was 23.5%, the proportion of macropores was 5.9%, the proportion of small pores was 94.1%, and the compressive strength reached 5.23 MPa.

[0023] Example 2

[0024] The raw material red mud content is 50%, bagasse content is 50%, and the water glass modulus is 1.25.

[0025] (3) Weigh 150 g of red mud and dry it in a drying oven at 100°C for 24 h. After drying, grind it in a ball mill for 3 h, and sieve out a powder with a particle size of 70-120 mesh for later use;

[0026] (4) 150 g of sugarcane bagasse was washed with water to remove impurities such as sand and then dried in a 50°C drying oven for 24 h. It was crushed using a ball mill and passed through a 100-mesh sieve. The powder at the bottom layer was collected. The ball-milled bagasse was pretreated with a dimethyl sulfoxide (DMSO) / Li Cl solution.

[0027] (3) 150g of red mud, 20% parametric water glass and 150g of prepared sucrose residue solution were mixed to form a mixed solution, which was added to a high-pressure reactor and reacted for 120 min at 220°C and 300 r / min. After the reaction was completed, the obtained product was filtered to separate the solid and liquid. After centrifugation, the supernatant filtrate was retained in a sample tube, and the residue was pressed into blocks;

[0028] (4) Samples were taken from the pressed raw materials for moisture testing, compressive strength testing, porosity testing, and 7-day curing testing. After 7 days, the moisture content was 7.2%, the total porosity was 25.9%, the proportion of macropores was 6.5%, the proportion of small pores was 93.5%, and the compressive strength reached 9.87 MPa.

[0029] Example 3

[0030] The raw material red mud content is 40%, bagasse content is 60%, and the water glass modulus is 1.25.

[0031] (5) Weigh 120 g of red mud and dry it in a drying oven at 100°C for 24 h. After drying, grind it in a ball mill for 3 h, and sieve out a powder with a particle size of 70-120 mesh for later use;

[0032] (6) 180 g of sugarcane bagasse was washed with water to remove impurities such as sand and then dried in a 50°C drying oven for 24 h. It was crushed using a ball mill and passed through a 100-mesh sieve. The lower layer of powder was collected. The ball-milled bagasse was pretreated with a dimethyl sulfoxide (DMSO) / Li Cl solution.

[0033] (3) 120g of red mud, 20% water glass and 180g of the prepared sucrose residue solution were mixed to form a mixed solution, which was added to a high-pressure reactor and reacted for 120 min at 220°C and 300 r / min. After the reaction was completed, the obtained product was filtered to separate the solid and liquid. After centrifugation, the supernatant filtrate was retained in a sample tube, and the residue was pressed into blocks;

[0034] (4) Samples of the pressed raw materials were taken for moisture testing, compressive strength testing, porosity testing, and 7-day curing testing. After 7 days, the moisture content was 8.3%, the total porosity was 25.7%, the macropores accounted for 6.8%, the small pores accounted for more than 93.2%, and the compressive strength reached 10.11 MPa.

Claims

1. A method for preparing a red mud-based bagasse fiber-reinforced composite gel material, involving red mud utilization, comprising the following steps: (1) The red mud is dried in a drying oven at 100°C for 24 hours, ground in a ball mill for 3 hours, and the powder with a particle size of 70-120 mesh is sieved out for later use; (2) The bagasse was washed with water to remove impurities such as sand and placed in a drying oven at 50°C for 24 h. It was crushed using a ball mill and passed through a 100-mesh sieve. The powder at the bottom layer was collected. The ball-milled bagasse was pretreated with a dimethyl sulfoxide (DMSO) / LiCl solution. (3) Red mud, water glass and the prepared sugarcane residue are mixed to form a mixed solution, which is added into a high-pressure reactor and reacted at 220°C and 300 r / min for 120 min. After the reaction is completed, the obtained product is filtered to separate the solid and liquid. After centrifugation, the supernatant filtrate is retained in a sample tube, and the filter residue is pressed into a block; (4) The compressed raw material is sampled for moisture testing, compressive strength testing, porosity testing, and 7-day curing testing. The red mud utilization rate of this method is 100%, the bagasse utilization rate is 100%, the total porosity is about 20%, the macropores account for 1%-5%, and the small pores account for more than 90%, respectively. The compressive strength reaches more than 5 MPa after 7 days.

2. The method for preparing a red mud-based bagasse fiber-reinforced composite gel material according to claim 1, characterized in that The particle size of the red mud treated by ball milling is 70-120 mesh.

3. The method for preparing a red mud-based bagasse fiber-reinforced composite gel material according to claim 1, characterized in that The bagasse was washed with water to remove impurities such as mud and sand, and then dried in a drying oven at 50°C for 24 h; it was crushed using a ball mill, passed through a 100-mesh sieve, and the lower layer of powder was collected. The ball-milled bagasse was pretreated with dimethyl sulfoxide (DMSO) / Li Cl solution; the characteristic of the process is that the bagasse is ball-milled to destroy the crystalline region of cellulose and loosen the structure of the wood cellulose, thereby facilitating the diffusion of the organic solvent into the interior of the wood cellulose molecules.

4. The method for preparing a red mud-based bagasse fiber-reinforced composite gel material according to claim 1, characterized in that Red mud, water glass and prepared bagasse were mixed to form a mixed solution, which was added to a high-pressure reactor and reacted for 120 min at 220°C and 300 r / min. After the reaction was completed, the obtained product was filtered to separate the solid and liquid. After centrifugation, the supernatant filtrate was retained in a sample tube, and the filter residue was briquette.

5. The method for preparing a red mud-based bagasse fiber-reinforced composite gel material according to claim 1, characterized in that The pressed raw materials are sampled for moisture testing, compressive strength testing, porosity testing, and 7-day curing testing. The characteristics are that the utilization rate of red mud is 100%, the utilization rate of bagasse is 100%, the total porosity is about 20%, the large pores account for 1%-5%, the small pores account for more than 90%, and the compressive strength reaches 5.23MPa after 7d.

Images