Method for preparing composite high-strength vitrified microsphere by using perlite tailings

Abstract

This invention belongs to the field of solid waste treatment technology, specifically disclosing a method for preparing composite high-strength vitrified microspheres using perlite tailings. First, the perlite tailings raw material is crushed and homogenized. Then, the homogenized perlite tailings raw material powder is mixed with perlite clinker, glass powder, a high-temperature composite foaming agent, and an adhesive in a specific ratio. Granulation is then performed in a granulator. Finally, expansion is carried out in a vortex expansion vitrification furnace to obtain composite high-strength vitrified microspheres, improving the utilization rate of perlite tailings. The composite high-strength closed-cell vitrified microspheres prepared by this invention using perlite tailings have advantages such as high strength, low water absorption, and low thermal conductivity. They can replace the most widely used lightweight materials, represented by expanded perlite, and are widely used in building energy-saving projects such as wall insulation, roof insulation, and composite insulation boards. The market demand is huge, and this method can effectively solve the environmental pollution problems caused by mineral tailings and waste residue.

Description

Technical Field

[0001] This invention belongs to the field of solid waste treatment technology, and specifically discloses a method for preparing composite high-strength vitrified microspheres using perlite tailings. Background Technology

[0002] Perlite tailings refer to solid waste with a particle size of less than 125μm generated after crushing and screening raw perlite ore; they are also known as perlite tailings sand or tailings. With the increasing demand for perlite and its products from various industries, the mining volume of raw perlite ore has been rising year by year. However, approximately 30-40% of the raw material is considered solid waste, resulting in extremely low utilization. This unutilized perlite tailings not only occupies a large amount of land resources, but also may contain harmful substances such as heavy metals and radioactive materials, which can pollute the surrounding environment and endanger human health. Comprehensive utilization of perlite tailings can not only reduce waste generation but also provide raw materials and energy for related industries, promoting economic development and improving the ecological environment. Therefore, it is urgent to explore and research comprehensive utilization pathways and methods for perlite tailings to achieve the dual goals of efficient resource utilization and environmental protection.

[0003] The doctoral dissertation, "Preparation of α-Cordierite Microcrystalline Glass from Perlite Tailings and Its Performance Study," proposes the use of perlite tailings to prepare cordierite microcrystalline glass applicable to low-temperature co-fired ceramic (LTCC) substrates, significantly reducing the production cost of microcrystalline glass. However, due to the complex and diverse composition of perlite tailings, the controllable preparation of cordierite microcrystalline glass from perlite tailings is currently not feasible. Chinese Patent (CN 112759364 A) discloses a foamed ceramic prepared using perlite tailings as a base material and its preparation method, which can greatly increase the added value of perlite tailings. However, this invention uses a large amount of environmentally unfriendly raw materials, such as alkylolamide foam stabilizers. Moreover, the preparation process of this invention (batching → wet grinding in a ball mill → granulation → secondary mixing → dry pressing → green body drying → green body stacking → firing → cold working) is relatively complex and difficult to automate. Chinese patent (CN107963904A) discloses a porous sound-absorbing ceramic and its preparation method made from perlite tailings powder and fly ash. The material has an apparent porosity of up to 30.8% and an average sound absorption coefficient of 0.43 at 200-1600 Hz, which greatly improves the added value of perlite tailings. However, although this invention patent has not been mass-produced since it was applied for in 2018, it indicates that the market demand for porous sound-absorbing ceramics is relatively small.

[0004] Vitrified microspheres are a lightweight filler and thermal insulation material with stable physical and chemical properties, strong anti-aging and weather resistance, as well as excellent thermal insulation, fire resistance and sound absorption properties. They are widely used in many fields such as industry, agriculture, building materials, chemical industry, metallurgy and light industry, and the market demand is huge. By using perlite tailings to prepare composite high-strength closed-cell vitrified microspheres, the added value of perlite tailings can be greatly improved and the effective utilization rate of perlite mineral resources can be increased. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention discloses a method for preparing composite high-strength vitrified microspheres using perlite tailings. The method involves crushing raw perlite tailings and homogenizing it, then mixing it with perlite clinker, glass powder, a high-temperature composite foaming agent, and an adhesive in a specific ratio. The mixture is then granulated in a granulator, and finally expanded in a vortex expansion vitrification furnace to obtain composite high-strength vitrified microspheres, thereby improving the utilization rate of perlite tailings.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing composite high-strength vitrified microspheres using perlite tailings involves first crushing the raw perlite tailings to obtain perlite tailings powder with a particle size of less than 80 μm. The perlite tailings powder is then placed in a homogenization chamber for homogenization. The homogenized perlite tailings powder, perlite clinker, glass powder, high-temperature composite foaming agent, and binder are weighed according to the raw material ratio and mixed evenly. The resulting powder mixture is then granulated using a granulation process to obtain microsphere blanks. Finally, the microsphere blanks are dried and then expanded in a vortex expansion vitrification furnace. During the vortex expansion vitrification furnace process, the glass powder first melts to block the pores of the vitrified microspheres and promotes the melting of the perlite tailings and perlite clinker. As the temperature further increases, the gas generated by the composite foaming agent causes the vitrified microspheres to expand, ultimately forming composite high-strength closed-cell vitrified microspheres with a porous internal structure and a dense and hard glaze layer on the surface.

[0008] Furthermore, in the method for preparing composite high-strength vitrified microspheres using perlite tailings, the raw material proportions by weight are as follows: perlite tailings powder: 65-80 parts; perlite clinker: 5-25 parts; glass powder: 5-25 parts; high-temperature composite foaming agent: 0-8 parts; adhesive: 0-3 parts.

[0009] Furthermore, in the method for preparing composite high-strength vitrified microspheres using perlite tailings, the perlite tailings raw material refers to the waste residue generated after processing perlite ore sand, with an expansion ratio K0 of less than 10 and a silica content between 50 and 68 wt%.

[0010] Furthermore, in the method for preparing composite high-strength vitrified microspheres using perlite tailings, the perlite clinker refers to perlite powder that has undergone high-temperature treatment, and the perlite clinker has a particle size of less than 80 μm. The main purpose of the perlite clinker is to reduce the bulk density of the vitrified microsphere blank.

[0011] Furthermore, in the method for preparing composite high-strength vitrified microspheres using perlite tailings, the softening point temperature of the glass powder is 625–745°C, the content of amorphous silica in the glass powder is greater than 60%, and the particle size is <80 μm.

[0012] Furthermore, in the method for preparing composite high-strength vitrified microspheres using perlite tailings, the high-temperature composite foaming agent is a composite of silicon carbide, carbon, and iron oxide with a particle size <45μm. The mass ratio of carbon to iron oxide is 0.04. The foaming mechanism first promotes the expansion of the vitrified microspheres by reacting silicon carbide with oxygen to form carbon dioxide. In the absence of oxygen, the expansion is caused by the carbon dioxide generated by the reaction of carbon and iron oxide.

[0013] Furthermore, in the method for preparing composite high-strength vitrified microspheres using perlite tailings, the dispersant is sodium tripolyphosphate and / or sodium hexametaphosphate with a particle size of less than 80 μm.

[0014] Furthermore, in the method for preparing composite high-strength vitrified microspheres using perlite tailings, the adhesive is dextrin and / or carboxymethyl cellulose with a particle size of less than 80 μm. The main function of the adhesive is to firmly bond the materials together and give the vitrified microsphere blank strength. It will be completely burned off during the high-temperature treatment process.

[0015] Furthermore, in the method for preparing composite high-strength vitrified microspheres using perlite tailings, the particle size is controlled between 10 mesh and 20 mesh.

[0016] Furthermore, in the method for preparing composite high-strength vitrified microspheres using perlite tailings, the granulation process employs extrusion granulation, stirring granulation, or spray drying granulation.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] This invention discloses a method for preparing composite high-strength vitrified microspheres using perlite tailings. First, the perlite tailings raw material is crushed and homogenized. Then, the homogenized perlite tailings powder is mixed with perlite clinker, glass powder, a high-temperature composite foaming agent, and an adhesive in a specific ratio. The mixture is then granulated in a granulator. Finally, it undergoes expansion in a vortex expansion vitrification furnace to obtain composite high-strength vitrified microspheres, thus improving the utilization rate of perlite tailings. The composite high-strength closed-cell vitrified microspheres prepared by this invention using perlite tailings have advantages such as high strength, low water absorption, and low thermal conductivity. They can replace the most widely used lightweight materials, such as expanded perlite, and are widely used in building energy-saving projects, including wall insulation, roof insulation, and composite insulation boards. The market demand is huge, and this method can effectively solve the environmental pollution problems caused by mineral tailings and waste.

[0019] This invention discloses a method for preparing composite high-strength closed-cell vitrified microspheres using perlite tailings. The preparation process is simple, can be automated, and uses environmentally friendly inorganic non-metallic materials. The glass powder can be made from solid waste from daily household glass products, which has environmental protection characteristics, can be produced in a planned manner, and can meet market demand. Attached Figure Description

[0020] Figure 1a Images of composite high-strength closed-cell vitrified microspheres with a particle size of 50 mm prepared according to this invention;

[0021] Figure 1b This is an enlarged view of the structure of the composite high-strength closed-cell vitrified microspheres with a particle size of 2 mm prepared according to the present invention;

[0022] Figure 2 This is a schematic diagram of the strength test of a single vitrified microsphere in this invention. Detailed Implementation

[0023] To help those skilled in the art better understand the differences between the present invention and the prior art, the present invention will be further described below with reference to specific embodiments. The content described in the embodiments should not be construed as a limitation of the present invention.

[0024] The composite high-strength closed-cell vitrified microspheres in the following examples are all based on a unified preparation method and performance index testing.

[0025] The preparation process of the composite high-strength closed-cell vitrified microspheres in this application is as follows:

[0026] S1. Crushed material: Perlite tailings raw material is crushed in a horizontal air jet mill to obtain powder with a particle size of less than 80μm. The powder is then placed in a homogenization silo for homogenization and storage.

[0027] S2. Ingredients: Weigh perlite tailings powder, perlite clinker, high-temperature composite foaming agent, glass powder, dispersant and binder raw materials according to the proportion of raw materials;

[0028] The chemical composition of the glass powder is as follows:

[0029] Chemical composition <![CDATA[SiO2]]> <![CDATA[Na2O]]> CaO <![CDATA[Al2O3]]> MgO <![CDATA[K2O]]> <![CDATA[SO2]]> mass wt% 70.55 10.97 7.72 4.63 3.94 0.54 0.44

[0030] The chemical composition of the high-temperature composite foaming agent is as follows:

[0031] Chemical composition SiC <![CDATA[Fe2O3]]> C Mass (wt%) 60 38.46 1.54

[0032] The adhesive is sodium carboxymethyl cellulose and / or dextrin with a particle size <45 μm.

[0033] The dispersant is sodium tripolyphosphate and / or sodium hexametaphosphate with a particle size <45μm.

[0034] S3. Mixing: Place the weighed raw materials into a mixer and mix for 45 minutes;

[0035] S4. Granulation: Place the uniformly mixed raw materials into a granulator for granulation. The particle size is controlled between 10 mesh and 20 mesh. The moisture content of the dried green body is less than 5.0 wt%.

[0036] S5. Expansion Treatment: The dried microsphere preform is placed in a vortex expansion vitrification furnace for expansion, ultimately obtaining composite high-strength closed-cell vitrified microspheres with a porous internal structure and a dense, hard glaze layer on the surface, such as... Figure 1a and Figure 1b As shown.

[0037] Performance testing: Test the bulk density, water absorption rate and single particle strength of the vitrified microspheres.

[0038] The bulk density test method for the vitrified microspheres is as follows:

[0039] Specific gravity is the ratio of the mass of vitrified microspheres that accumulate naturally in a fixed-volume cylinder to the volume of the cylinder. The formula is: ρ = M / V, where ρ is the specific gravity of the vitrified microspheres, in g / cm³. 3 M represents the mass of the vitrified microspheres, in grams; V represents the volume of the cylinder, in centimeters. 3 .

[0040] The single-particle strength of the vitrified microspheres was determined according to experimental methods proposed by foreign scholars, such as... Figure 2 As shown, the compressive strength of 10 vitrified microspheres was tested using a 500N press, and then the average value was calculated.

[0041] The strength of a single vitrified microsphere is calculated using the following formula.

[0042]

[0043] In the formula: S is the compressive strength of a single ceramic particle, in MPa; PC is the load at which the vitrified microspheres break, in N; X is the diameter of the vitrified microspheres, in mm.

[0044] The method for testing the water absorption rate of the vitrified microspheres is as follows:

[0045] First, weigh 20 vitrified microspheres (m0). Then, immerse the vitrified microsphere sample in water for 1 hour, and weigh it again, recording the weight as m1. The calculation formula is as follows:

[0046] Water absorption rate = (m1 - m0) / m0

[0047] In the formula: m1 is the wet weight of 20 vitrified microspheres, in g; m0 is the dry weight of 20 vitrified microspheres, in g.

[0048] The experimental process will not be described again in the examples.

[0049] Example 1

[0050] A method for preparing composite high-strength closed-cell vitrified microspheres using perlite tailings, with the following raw material proportions by weight: perlite tailings: 65 parts; perlite clinker: 10 parts; glass powder: 25 parts; high-temperature composite foaming agent: 1 part; sodium carboxymethyl cellulose: 3 parts.

[0051] Example 2

[0052] A method for preparing composite high-strength closed-cell vitrified microspheres using perlite tailings, with the following raw material proportions: perlite tailings: 65 parts; perlite clinker: 10 parts; glass powder: 25 parts; high-temperature composite foaming agent: 7 parts; sodium carboxymethyl cellulose: 1 part.

[0053] Example 3

[0054] A method for preparing composite high-strength closed-cell vitrified microspheres using perlite tailings, with the following raw material proportions: perlite tailings: 65 parts; perlite clinker: 25 parts; glass powder: 10 parts; high-temperature composite foaming agent: 6 parts; dextrin: 1 part.

[0055] Example 4

[0056] A method for preparing composite high-strength closed-cell vitrified microspheres using perlite tailings, with the following raw material proportions: perlite tailings: 70 parts; perlite clinker: 10 parts; glass powder: 20 parts; high-temperature composite foaming agent: 7 parts; sodium carboxymethyl cellulose: 1 part.

[0057] Example 5

[0058] A method for preparing composite high-strength closed-cell vitrified microspheres using perlite tailings, with the following raw material proportions: perlite tailings: 75 parts; perlite clinker: 10 parts; glass powder: 15 parts; high-temperature composite foaming agent: 6 parts; sodium carboxymethyl cellulose: 1 part.

[0059] Example 6

[0060] A method for preparing composite high-strength closed-cell vitrified microspheres using perlite tailings, with the following raw material ratios: perlite tailings: 80 parts; perlite clinker: 5 parts; glass powder: 15 parts; high-temperature composite foaming agent: 5 parts; dextrin: 1 part.

[0061] The comparative sample was high-quality expanded perlite sold in the market.

[0062] The performance test results of the composite high-strength closed-cell vitrified microspheres prepared in Examples 1-6 and the comparative samples are shown in Table 1.

[0063] Table 1. Performance test results of vitrified microspheres prepared in the examples and comparative samples.

[0064] project <![CDATA[Unit weight (kg / m 3 )]]> Single particle compressive strength (MPa) Water absorption rate (%) Example 1 317 1.53 0.21 Example 2 295 1.47 0.26 Example 3 298 1.50 0.22 Example 4 261 0.98 0.39 Example 5 258 0.89 0.51 Example 6 289 1.34 0.31 Comparative sample 251 0.51 0.84

[0065] As shown in Table 1, the composite high-strength closed-cell vitrified microspheres prepared by this invention have a single particle compressive strength superior to that of commercially available high-quality expanded perlite, lower water absorption, and a density close to that of commercially available high-quality expanded perlite. The composite high-strength closed-cell vitrified microspheres prepared by this invention can replace expanded perlite and are widely used in building energy-saving projects such as wall insulation, roof insulation, and composite insulation boards. The market demand is huge, and it can effectively solve the environmental pollution problems caused by mineral tailings and waste residue.

[0066] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the details described herein.

Claims

1. A method for preparing composite high-strength vitrified microballoons by using perlite tailings, characterized by: First, the perlite tailings raw material is crushed to obtain perlite tailings powder with a particle size of less than 80μm. The perlite tailings powder is placed in a homogenization silo for homogenization treatment. The homogenized perlite tailings powder, perlite clinker, glass powder, high-temperature composite foaming agent and binder are weighed according to the raw material ratio and mixed evenly. The resulting powder mixture is granulated by a granulation process to obtain microsphere preforms. Finally, the microsphere preforms are dried and expanded in a vortex expansion vitrification furnace to obtain high-strength composite vitrified microspheres. The raw material proportions, by weight, are as follows: perlite tailings powder: 65-80 parts; perlite clinker: 5-25 parts; glass powder: 10-25 parts; high-temperature composite foaming agent: 1-7 parts; binder: 1-3 parts. The perlite tailings raw material refers to the waste residue generated after processing perlite ore sand, with an expansion ratio K0 of less than 10 and a silica content between 50 and 68 wt%. The perlite clinker refers to perlite powder that has undergone high-temperature treatment, and the perlite clinker has a particle size of less than 80μm. The softening point temperature of the glass powder is 625-745℃, the content of amorphous silica in the glass powder is greater than 60%, and the particle size is <80μm. The chemical composition of the glass powder is as follows (by mass percentage): SiO2 70.55%, Na2O 10.97%, CaO 7.72%, Al2O3 4.63%, MgO 3.94%, K2O 0.54%, SO2 0.44%; The high-temperature composite foaming agent refers to a composite material with a mass percentage of 60% silicon carbide, 1.54% carbon, and 38.46% iron oxide.

2. The method for preparing composite high-strength vitrified microballoons by using perlite tailings according to claim 1, characterized in that: The adhesive is dextrin and / or carboxymethyl cellulose with a particle size of less than 80 μm.

3. The method for preparing composite high-strength vitrified microspheres using perlite tailings according to claim 1, characterized in that: The granulation particle size is controlled between 10 mesh and 20 mesh.

4. The method for preparing composite high-strength vitrified microspheres using perlite tailings according to claim 1, characterized in that: The granulation process employs extrusion granulation, stirring granulation, or spray drying granulation.

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