Method for producing lightweight porous material particles

Abstract

To provide a method for producing lightweight porous material particles with a silica-alumina material and a waste substance, the porous material particles having extensive particle size distribution.SOLUTION: A method for producing lightweight porous material particles includes the steps of: (1) preparing silica-alumina material particles; (2) preparing a slurry mixture containing silica-alumina material particles, a viscosity modifier, a reactive mineralizing agent and water; (3) drying the slurry mixture to form a mineral matrix; (4) crushing the mineral matrix and sieving it to form first particles, leaving particles having a particle size of 150 μm or more; and (5) mixing the first particles with an antitack agent, sintering the resultant mixture, and swelling to form second particles which are porous material particles.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a manufacturing method for producing lightweight porous material particles from silica-alumina raw materials or waste materials.

Background Art

[0002] Lightweight aggregates are mineral pellets having a porous structure, and generally refer to porous pellets having a particle density smaller than 1.8 g / cm 3 Lightweight aggregates are formed by sintering at a high temperature after granulation. They contain a closed pore structure inside, have fire resistance, and also have sound insulation, heat insulation, and lightweight effects in terms of structure. Lightweight porous material particles have properties such as heat insulation, sound insulation, and weight reduction, and are applicable to application fields such as functional construction materials, heat-insulating and sound-insulating paints, lightweight composite material fillers, flame retardant material fillers, insulating encapsulant additives with a low dielectric constant, and rust preventive coatings.

[0003] Artificial lightweight aggregates and expanded glass are usually formed by heating a base material to a high temperature in a high-temperature sintering process, partially melting the base material to form a glassy liquid phase having an appropriate viscosity, and utilizing the principle that gas generation sources inside the base material are released by heating. Since the molten base material has the characteristics of a highly viscous glassy liquid phase, the gas released from inside the base material is restrained by the viscous glassy liquid phase and is less likely to spout or escape. Furthermore, due to the increase in volume, the glassy liquid phase structure of the base material is expanded, a porous cell clutch structure is formed, and the effect of foaming expansion is achieved.

[0004] Common artificial lightweight aggregates in the prior art can be manufactured from natural materials such as clay, shale, slate, etc., and industrial waste and environmental waste such as incineration ash, blast furnace slag, sewage sludge, and silt can also be processed by heat treatment or cooling and solidification. However, since the manufacturing process is in a high-temperature environment, the base materials granulated by injection molding or spray drying will all have each particle in a glassy liquid phase form in the high-temperature environment. In this case, the base materials to be granulated will contact and stick to each other due to the melt viscosity of the materials, and single-particle artificial lightweight aggregates or expanded glass cannot be formed. Many artificial lightweight aggregates are composed of high-alumina components, and in the manufacturing process of expansion sintering, it is necessary to perform sintering treatment at a high temperature (1100 - 1200 °C), and the problems of high energy consumption and high manufacturing cost have existed for many years. Also, the performance of artificial lightweight aggregates may vary greatly depending on the production area, raw materials, manufacturing method, etc. The particle density after expansion and foaming is about 0.9 - 1.4 g / cm 3

[0005] ​As another type of artificial lightweight aggregate, there is expanded glass manufactured mainly from recycled glass. Expanded glass is produced by mixing crushed glass with an expanding agent, a thickening agent, and an aqueous solution, and then sintering at high temperature in a kiln. It has properties such as fire resistance, non-toxicity, insulation, heat insulation, sound insulation, and electromagnetic wave prevention, and can be widely applied in fields such as construction, chemical engineering, and military. However, in order to produce expanded glass from recycled glass, it is often necessary to first perform color separation treatment and classification treatment according to the silicon content. Also, expanded glass can only be produced from specific types of recycled glass, and there are many restrictions on the use of raw materials. In addition, expanded glass produced by mixing crushed glass, an expanding agent, a thickening agent, and water or an aqueous solution, and then by injection molding and sintering, has a large particle form and limited application fields due to its excessive volume, making it inconvenient to use. Furthermore, the spray drying method commonly used in the manufacturing process removes the moisture of the atomized glass slurry with hot air and then produces expanded glass particles. Although it can produce small particle expanded glass (0.1 - 2 mm), it cannot produce expanded glass with a wide size range in a single manufacturing process. Also, the spray drying method usually requires the use of hot air at a temperature higher than 200°C for moisture removal operations, which requires a relatively large amount of energy in terms of energy use and is not environmentally friendly.

[0006] Therefore, in this industry, there is a great need for a manufacturing process and apparatus for lightweight aggregate particles that are simpler, more energy-saving, and can accommodate a wider size range and types of raw materials.

Summary of the Invention

[0007] In this industry, for example, there are many silica-alumina based wastes such as waste glass containers, waste solar power generation panels, waste automotive glass, waste glass fibers, and chemical mechanical polishing slurry sludge for semiconductors. Due to problems such as usually containing mixtures and impurities, these wastes cannot be effectively recovered and reused. Currently, they are either discarded, landfilled, or treated expensively by landfill or incineration, which not only causes environmental pollution but also shortens the service life of landfills and incinerators.

[0008] Waste glass containers, waste solar panel glass, waste glass for automobiles, waste glass fibers, silica-alumina-based waste such as chemical mechanical polishing slurry sludge for semiconductors contain a large amount of silica (SiO 2 ) components. By a special mineralization and modification technology, the waste can be converted into a foamable material capable of thermal expansion. Furthermore, if the granulation process can be carried out by a simple and high-speed mechanical crushing method and then heat-sintered and expanded into a new recycled material, not only will the sintering temperature decrease and the energy consumption be reduced, but it will also have high performance characteristics such as a lower density, lower water absorption, and higher heat insulation compared to conventional artificial lightweight aggregates, contributing to environmental protection and resource sustainability. Lightweight porous material particles with a wide range of sizes can more effectively improve the application fields of downstream material technologies and increase the functional value of products.

[0009] Therefore, an object of the present invention is to provide a manufacturing method for producing lightweight porous material particles using a silica-alumina-based raw material, preferably a recovered material or waste. Waste containing a silica-alumina component is used to produce a powder raw material through a pulverization or polishing process. An appropriate reactant and medium are added and reacted by stirring to form a plastic slurry. After drying at an appropriate temperature, it is formed into a bulk synthetic mineral base material capable of thermal expansion. Next, the bulk base material is mechanically crushed to a desired size, screened, and then an anti-sticking agent is added and mixed, and converted into lightweight porous material particles by sintering and expansion. The lightweight porous material particles have characteristics such as heat insulation, sound insulation, and weight reduction, and can be applied to application fields such as functional construction materials, heating and cooling paints, and lightweight fillers.

[0010] Therefore, the present invention Step (1) of preparing silica-alumina-based raw material particles; Step (2) of preparing a slurry mixture containing the silica-alumina-based raw material particles, a viscosity modifier, a reactive mineralizer, and water; Step (3) of drying the slurry mixture to form a mineral base material; Step (4) of crushing the mineral base material to form mineral base material particles, screening the mineral base material particles, leaving particles with a particle size of 150 μm or more, and obtaining first particles; A method for manufacturing lightweight porous material particles is provided, including step (5) of mixing the first particles with an anti-adhesive agent, sintering, and expanding to form second particles which are lightweight porous material particles.

Brief Description of the Drawings

[0011] [Figure 1] It is a flowchart of a specific embodiment of the method claimed by the present invention.

Modes for Carrying Out the Invention

[0012] Hereinafter, the embodiments and concepts of the present invention will be described in more detail.

[0013] (Silica-alumina raw material, silica-alumina raw material particles and their production) The silica-alumina raw material used in the present invention has SiO as the main component 2 and Al 2 O 3 included. The content of SiO 2 may be 48 wt% - 95 wt%, preferably 55 wt% - 80 wt%, more preferably 60 wt% - 70 wt%, or the content of SiO 2 may be a reasonable numerical range defined by the above endpoints. The content of Al 2 O 3 may be 1 wt% - 30 wt%, preferably 1.5 wt% - 15 wt%, more preferably 2 wt% - 5 wt%, or the content of Al 2 O 3The content is within a reasonable numerical range defined by the above endpoints. The water content of the raw material itself is not particularly limited, but usually, a drying operation may be performed before processing, and the drying operation is advantageous for subsequent manufacturing processes or control of material properties. The water content of the silica-alumina raw material after drying is usually lower than 1% by weight, and the impurities are lower than 10% by weight, preferably lower than 5% by weight, and more preferably lower than 3% by weight. The types of silica-alumina raw materials are extensive, and natural materials, industrial waste, etc. can all be used as raw materials for manufacturing lightweight porous materials. Examples of natural materials include, but are not limited to, clay, shale, slate, perlite, etc. Examples of recyclable materials or waste include, for example, silica-based industrial by-products such as sheet glass, waste glass containers, waste solar power generation panels, automotive waste glass, waste glass fibers, chemical mechanical polishing sludge for semiconductors, granulated slag, fly ash, polished quartz brick sludge, waste foundry sand, etc., but are not limited to these. The composition of the raw material can be restricted or adjusted according to the end use or demand. For example, it is possible to use some natural materials in combination with industrial recyclables or waste, or to use different types of industrial recyclables or waste in combination, etc.

[0014] After preparing the silica-alumina raw material, first, the silica-alumina raw material is manufactured as particles with a particle size smaller than 150 μm and an unrestricted shape. Here, as the method for manufacturing the particles, conventional granulation, polishing, or mechanical means can be used.

[0015] In a specific example, the silica-alumina raw material particles contain two or more raw materials and are formed by polishing the raw materials together or separately.

[0016] (Slurry mixture and its production) Next, the silica-alumina raw material particles are mixed with a viscosity modifier, a reactive mineralizer, and water, and after stirring, they are reacted to form a plastic slurry mixture.

[0017] The viscosity modifier is a reagent that adjusts the rheological properties of the plastic slurry by adjusting the viscosity. It is used to change the flow and deformation ability of the fluid. For example, after adding the viscosity modifier, the slurry changes from a freely flowing fluid to a viscous liquid or solid that flows slowly. One purpose of viscosity adjustment is to make the viscosity of the slurry mixture exhibit fluidity suitable for stirring or transportation so that the subsequent manufacturing process can be easily transported. Examples of viscosity modifiers include, but are not limited to, other silicates (such as fine powders) that do not affect the components or properties after the slurry dries. Or, the powder material or the particles themselves after drying the slurry (regardless of whether other viscosity modifiers are added before drying) may also be used as viscosity modifiers. Water may be added alone, or added to the reaction of the siliceous raw material particles as an aqueous solution to facilitate uniform stirring of the mixture.

[0018] The aqueous solution may contain a mineralizer such as an alkali metal hydroxide or an alkali metal silicate. Without being bound by theory, the role of the mineralizer is to recombine the broken bonds with the silica-alumina raw material and form a gas generation source necessary for expansion.

[0019] Specifically, the role of the (reactive) mineralizer is to enable the silica-alumina raw material particles to perform the mineralization action. The hard structure of the siliceous raw material softens by the action of the (alkaline) mineralizer and becomes a glass phase that can be molded and expanded when heated, generating a thermally expandable glass phase. Due to the gas generation source and the glass phase formed by the recombination of the broken bonds of the raw material, in the process of heat sintering, a plastic molten glass phase with high viscosity is formed on the surface, and the internal gas generation source vaporizes due to the temperature rise and the volume expands. When the internal gas releases pressure to the outside, it cannot pass through due to the presence of the high-viscosity molten glass phase. As a result, the gas is encapsulated inside the glass phase, the volume of the plastic molten glass phase expands, and the properties of the porous material are formed. As an example of an operation, in the process of glass manufacturing, it includes putting hard silica sand into soda, for example, to manufacture glass.

[0020] In a specific example, the slurry mixture includes 65 wt% to 85 wt%, or 65 wt% to 75 wt%, preferably 65 wt% to 70 wt% of silica-alumina raw material particles, 0.5 wt% to 10 wt%, or 0.5 wt% to 6 wt%, preferably 1 wt% to 3 wt% of a viscosity modifier, and 3 wt% to 33 wt%, or 15 wt% to 35 wt%, preferably 5 wt% to 10 wt% of a reactive mineralizer, and the balance may be water added as required to make up 100 wt%.

[0021] In a specific example, there is no need to further polish the slurry mixture. After adjusting and controlling the size of raw material particles such as silica-alumina raw materials, a mineralization reaction is directly carried out to form a glass phase capable of forming and expanding.

[0022] (Mineral matrix, mineral matrix particles and their production) After performing the steps of drying and hardening and solidifying the slurry mixture, a bulk mineral matrix capable of thermal expansion is formed. The application temperature during the drying and hardening and solidifying steps may be 60°C to 600°C, and its main purpose is to vaporize and remove the moisture in the solid material. As the operation method, methods such as natural drying, hot air drying, and vacuum drying can be used. In a specific example, the steps of drying and hardening and solidifying remove the moisture of the slurry mixture with hot air below 600°C and perform a drying and solidifying (drying and hardening and solidifying) operation to obtain a bulk synthetic mineral matrix capable of thermal expansion. In another specific example, good production efficiency and effects can be obtained by performing a drying and solidifying operation with hot air at 80°C to 150°C.

[0023] After obtaining the mineral base material, the mineral base material is mechanically crushed to form particles, and the particle size is 1 μm to 10 mm, for example, about 1 μm, about 5 μm, about 10 μm, about 20 μm, about 50 μm, about 100 μm, about 150 μm, about 200 μm, about 300 μm, about 400 μm, about 500 μm, about 600 μm, about 700 μm, about 800 μm, about 900 μm, about 1 mm, about 2 mm, about 3 mm, about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 10 mm, preferably, for example, 150 μm to 5 mm, or the particle size is a reasonable numerical range defined by any of the above endpoints. Examples of mechanical crushing include, but are not limited to, crushing of lumps by mechanical impact, pressing, high-speed impact of air flow, or combinations thereof, thereby forming particles of a plurality of mineral base materials.

[0024] To facilitate the subsequent sintering process, the mineral base material particles are sieved by size to obtain particles with a particle size of 200 μm or more, or 150 μm or more.

[0025] (Sintering) An anti-sticking agent is added to the sieved mineral base material particles, uniformly mixed, and then sintered to produce lightweight porous material particles.

[0026] The composition of the anti-sticking agent and the mineral base material is very different, especially in the composition of SiO 2 / Al 2 O 3 There is a significant difference, and the purpose is to prevent the problem of particles sticking to each other during the high-temperature sintering process. In a specific example, the particle size of the anti-sticking agent is 150 μm or less, for example, 100 μm or less, 50 μm or less, preferably 30 μm or less. The particle size of the anti-sticking agent may ultimately be determined according to the particle size of the desired lightweight porous material particles, as long as the particle size of the anti-sticking agent is less than or equal to the particle size of the mineral base material particles and the anti-sticking agent itself does not agglomerate at the sintering temperature. For example, heat-resistant ceramic powders, etc. have such characteristics.

[0027] The uniformly mixed anti-sticking agent and the sieved mineral base material particles may be put into a dynamic rotary kiln or a static tunnel kiln for sintering and expansion. The sintering temperature may be an environmental temperature of 600°C to 900°C, thereby forming a lightweight porous particle material having a plurality of pores inside.

[0028] After the sintering is completed, the anti-sticking agent is removed to obtain a lightweight porous particle material. For example, the sintered product may be further sieved.

[0029] (Finished lightweight porous particles) The size of the lightweight porous particles produced by the method of the present invention is 150 μm to 20 mm, preferably 150 μm to 8 mm. For example, it can have any size with endpoints such as 150 μm, 200 μm, 300 μm, 4000 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, or a size within a reasonable numerical range defined by these endpoints. The bulk density (bulk unit weight) of the material is in the range of 120 to 350 Kg / m 3 within the range, for example, within the range of 150 to 300 Kg / m 3 within the range. The cylindrical compressive strength is 1.5 to 10.0 Mpa, for example, 2 to 5.0 Mpa.

Example

[0030] The properties of commercially available lightweight aggregates and exemplary lightweight porous material particles produced by the method of the present invention are shown in the following table.

Table 1

[0031] From the above characteristics, it can be seen that the lightweight porous material (particles) of the present invention has the following excellent characteristics. It has a wide particle size distribution and can be widely applied in various technical fields. Its bulk unit weight is very low, which improves the usability and makes the advantages of its application in weight reduction more obvious. Its water absorption rate is even lower. In the application of aqueous solution-related products, the characteristics of the material are less likely to change due to the addition of the lightweight porous material, and there is no need to change the amount of added water when it is used on the application side. Its cylindrical compression strength is equivalent to or higher than that of commercially available materials. It has been shown that the material can obtain more favorable effects without sacrificing durability while having a very low bulk unit weight, so that on the application side, it can reach higher-strength materials and is not restricted by the negative effect that the strength of the material after addition decreases due to the low strength of the lightweight aggregate itself. Its thermal conductivity is much lower than that of commercially available products, which is more advantageous for heat insulation-related applications. In addition, the manufacturing method applied to the developed lightweight aggregate can produce lightweight porous particle materials with clear individual particles without adhesion and aggregation due to the melting characteristics of the base material during the sintering process, and the production efficiency is higher.

[0032] Therefore, the present invention brings environmental protection effects such as the reduction of industrial by-products or waste and resource recycling, and fully practices a practical method of circular economy through the sustainable high-value application of resources.

[0033] It is obvious to those skilled in the art that various modifications and changes can be made to the content of the present invention without departing from the scope or spirit of the present invention. In view of the above, the present invention is intended to include all such modifications and changes as long as they are included within the scope of the following claims and their equivalents. The present invention includes, for example, the following embodiments. [Item 1] Step (1) of preparing silica-alumina raw material particles, Step (2) of preparing a slurry mixture containing the silica-alumina raw material particles, a viscosity modifier, a reactive mineralizer, and water, Step (3) of drying the slurry mixture to form a mineral matrix, Step (4) of crushing the mineral matrix to form mineral matrix particles, sieving the mineral matrix particles, leaving particles with a particle size of 150 μm or more, and obtaining first particles, A method for producing lightweight porous material particles, comprising: Step (5) of mixing the first particles with an anti-sticking agent, sintering, and expanding to form second particles which are lightweight porous material particles. [Item 2] The method according to Item 1, wherein the crushing in Step (4) is performed by mechanical impact, pressing, high-speed impact of air flow, or a combination thereof. [Item 3] The method according to Item 1, wherein the slurry mixture in Step (2) contains 65 wt% to 85 wt% of the silica-alumina raw material particles, 0.5 wt% to 10 wt% of the viscosity modifier, and 3 wt% to 35 wt% of the reactive mineralizer. [Item 4] The method according to Item 1, wherein the particle size of the mineral matrix particles in Step (4) is 1 μm to 10 mm. [Item 5] The method according to Item 1, wherein the second particles in Step (5) are 150 μm to 20 mm. [Item 6] The method according to Item 1, wherein the particle size of the anti-sticking agent in Step (5) is less than or equal to the particle size of the first particles. [Item 7] The method according to Item 1, further comprising Step (6) of further sieving the sintered product to remove the anti-sticking agent. [Item 8] The method according to Item 1, wherein the silica-alumina raw material particles in Step (1) contain two or more raw materials, and the raw materials are polished together or separately. [Item 9] The method according to Item 1, wherein the sintering in Step (5) is performed in a rotary kiln or a tunnel kiln.

Claims

1. Step (1) of preparing silica-alumina raw material particles; Step (2) of preparing a slurry mixture containing the silica-alumina raw material particles, the viscosity modifier, the mineralizer, and water, where the silica-alumina raw material contains 48% to 70% by weight of SiO ２ and 1% to 30% by weight of Al ２ O ３ and without further polishing the slurry mixture Step (3) of drying the slurry mixture to form a massive mineral base material; Step (4) of crushing the massive mineral base material to form mineral base material particles, sieving the mineral base material particles, leaving particles with a particle size of 150 μm or more, and obtaining first particles; Step (5) of mixing the first particles with an anti-sticking agent, sintering, and expanding to form second particles which are lightweight porous material particles. Here, the particle size of the anti-sticking agent is equal to or less than the particle size of the first particles, and the sintering temperature is 600°C to 900°C; A method for manufacturing lightweight porous material particles, comprising the above steps.

2. The method according to Claim 1, wherein the crushing in Step (4) is performed by mechanical impact, pressing, high-speed impact of air flow, or a combination thereof.

3. The method according to Claim 1, wherein the slurry mixture in Step (2) contains 65 wt% to 85 wt% of the silica-alumina raw material particles, 0.5 wt% to 10 wt% of the viscosity modifier, and 5 wt% to 33 wt% of the mineralizer.

4. The method according to Claim 1, wherein the particle size of the mineral base material particles in Step (4) is 1 μm to 10 mm.

5. The method according to Claim 1, wherein the second particles in Step (5) are 150 μm to 20 mm.

6. The method according to Claim 1, wherein the particle size of the anti-sticking agent in Step (5) is 150 μm or less.

7. The method according to Claim 1, further comprising Step (6) of further sieving the sintered product to remove the anti-sticking agent.

8. The method according to Claim 1, wherein the silica-alumina raw material particles in Step (1) contain two or more raw materials, and the raw materials are polished together or separately.

9. The method according to Claim 1, wherein the sintering in Step (5) is performed in a rotary kiln or a tunnel kiln.

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