Porcelain shell expanded perlite as well as preparation method and application thereof

Abstract

The invention provides expanded perlite with a porcelain shell and a preparation method and application thereof, and the preparation method comprises the following steps: pretreating perlite ore to obtain first perlite particles; proportioning the first perlite particles and a binder according to a mass ratio, and uniformly mixing the first perlite particles and the binder to obtain second perlite particles; sequentially adding vitreous cladding powder and porcelain cladding powder into the second perlite particles for granulation to sequentially obtain A-type third perlite particles and B-type third perlite particles; carrying out drying and preheating treatment on the B-type third perlite particles to obtain fourth perlite particles; and carrying out high-temperature expansion treatment on the fourth perlite particles to obtain the expanded perlite with the porcelain shell. The ceramic shell expanded perlite prepared by the invention has a shell / core composite structure, the shell is a ceramic layer formed by sintering a ceramic cladding component, the core is an expanded product of the first perlite particles, and the ceramic shell expanded perlite has the characteristics of high expansion time, small bulk density, high cylinder compressive strength, low heat conduction coefficient, small water absorption rate, acid and alkali corrosion resistance and the like.

Description

Technical Field

[0001] This invention relates to the field of mineral and rock material processing and new materials, specifically to a ceramic-shell expanded perlite, its preparation method, and its application. Background Technology

[0002] Perlite is a type of glassy rock formed from acidic lava that has cooled rapidly after a volcanic eruption, known for its unique scaling and expansion properties. Under high-temperature conditions (generally 1000–1300℃), perlite particles can rapidly expand several times their original size, forming lightweight, porous, and heat-insulating, sound-insulating, fire-resistant, and flame-retardant common expanded perlite, also known as open-cell expanded perlite. Expanded perlite has shown broad application potential in many fields, especially as a raw material for lightweight and insulating materials, playing a vital role in the construction and manufacturing industries.

[0003] However, while expanded perlite produced by traditional methods possesses characteristics such as low bulk density, porosity, and low thermal conductivity, it also suffers from drawbacks including open cavities left by gas escape during the expansion process, irregular shape, low strength, and hygroscopicity. These problems often lead to a decline in product performance during preparation and use. For example, open cavities can easily allow the inclusion of cementitious / bonding material slurry, reducing its lightweight and thermal insulation properties, thereby lowering its application performance. To overcome these defects, researchers have tried various improvement methods, including organic modification and surface coating techniques. However, these methods often introduce new problems, such as affecting bond strength.

[0004] In recent years, the industry has been exploring production methods for expanded perlite with sealed or closed pores on the surface. With technological advancements, it is now possible to further heat the expanded perlite in an electric expansion furnace to partially melt the surface layer, producing closed-pore expanded perlite. This method, through precise temperature control, melts the glassy surface of the expanded perlite particles, forming a sealed shell and improving the material's strength and water resistance. However, this method requires secondary processing, has a long process flow, and complex equipment. Controlling the furnace temperature to melt the surface of the expanded perlite while keeping the interior unmelted remains a challenging problem. Furthermore, the secondary melting process affects the final product's properties, such as bulk density and thermal conductivity.

[0005] Therefore, it is of great significance to explore new production methods for closed-cell expanded perlite and overcome the defects of traditional methods, such as the open pores on the surface of expanded perlite, which easily lead to a reduction in the lightweight and thermal insulation properties of expanded perlite after the injection of cementitious / bonding material slurry.

[0006] This invention utilizes a coating method to coat perlite particles with a layer of glassy heterostructure and then a layer of ceramic heterostructure. When the coated perlite particles undergo expansion processing, the glassy heterostructure on the outer surface melts first and traps the gas released during the expansion process, while the ceramic heterostructure on the outer surface is sintered and solidified to form a continuous glassy layer and a less continuous, thicker ceramic layer. This not only creates closed-cell expanded perlite but also further improves the expansion ratio, sphericity, and overall performance. Furthermore, the discontinuous ceramic shell bonds better with the cementing or gelling materials. This novel shell / core structure of expanded perlite material possesses excellent properties such as low bulk density, low thermal conductivity, high sphericity, and high strength. In particular, during the molding process of lightweight and thermal insulation materials, the closed-cell structure of expanded perlite prevents the cementitious / bonding material slurry from being injected. The high sphericity allows for a higher degree of compact packing, thereby reducing the amount of cementitious / bonding material used. As a result, the resulting ceramic-shell expanded perlite lightweight and thermal insulation material has superior performance. Summary of the Invention

[0007] The purpose of this invention is to address at least one of the aforementioned deficiencies in the prior art. For example, one objective of this invention is a method for preparing porcelain-shell expanded perlite; a second objective is a porcelain-shell expanded perlite; and a third objective is the application of porcelain-shell expanded perlite.

[0008] To achieve the above objectives, the present invention provides a method for preparing porcelain-shell expanded perlite, the method comprising: 1) pretreating perlite ore to obtain first perlite particles; 2) mixing the first perlite particles with a binder in a mass ratio and mixing them evenly to obtain second perlite particles; 3) sequentially adding glassy shell powder and porcelain shell powder to the second perlite particles for granulation to obtain type A third perlite particles and type B third perlite particles; 4) drying and preheating the type B third perlite particles to obtain preheated fourth perlite particles; 5) subjecting the preheated fourth perlite particles to high-temperature expansion treatment to obtain porcelain-shell expanded perlite.

[0009] Alternatively, the perlite ore may include one or more of four types of ore: perlite-type, obsidian-type, resinstone-type, and pumice-like perlite.

[0010] Optionally, the pretreatment includes crushing, screening, and dust removal; the crushing is a crushing process with an inspection screening section, which further crushes the coarse perlite ore on the inspection screening screen to avoid over-crushing of perlite ore; the screening and dust removal include separating the crushed perlite ore into different particle sizes by screening, and collecting the micro powder with a particle size of less than 100 mesh from the perlite ore for use as raw material for preparing coating powder.

[0011] Optionally, the first perlite particles are perlite sand with a particle size range of +100 mesh to -10 mesh; the particle size specifications of the first perlite particles include multiple types from -10 mesh to +20 mesh, -20 mesh to +30 mesh, -30 mesh to +50 mesh, -50 mesh to +80 mesh, and -80 mesh to +100 mesh.

[0012] Alternatively, the mass ratio described in step 2) is 100:(4-9).

[0013] Alternatively, the uniform mixing includes: spraying the binder onto the first perlite particles being stirred using a spraying method, and uniformly coating the surface of the first perlite particles with the binder;

[0014] The second perlite particle is a perlite particle with a binder coated on its surface.

[0015] Alternatively, the adhesive may comprise one or more of inorganic and organic adhesives in an aqueous solution or hydrosol prepared with water;

[0016] The inorganic binder comprises one or more of water glass, sodium silicate, and potassium silicate with a modulus of 1.0 to 2.9, and is prepared as an aqueous solution with a density of 1.36 to 1.50 g / cm3 and a Baume degree of 38.4 to 48.3.

[0017] The organic binder includes one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, acrylic emulsion, vinyl acetate emulsion, polyvinyl alcohol acetal, emulsion glue, animal glue, and plant glue, and is formulated into a water-soluble adhesive with a solid content of 0.5% to 2.0% by mass.

[0018] Optionally, the granulation in step 3) involves first mixing the glassy coating component powder with the second perlite particles and bonding them with a surface binder of the perlite particles to form a glassy coating layer, then adding ceramic coating powder to continue granulation to form a ceramic coating layer. The granulation process includes:

[0019] Weigh the second perlite particles, glassy coating powder, and ceramic coating powder in a mass ratio of (76-84):(5-9):(11-15);

[0020] The weighed second perlite particles are placed in a granulator, and then the weighed glassy coating powder is evenly added to the running granulator so that the glassy coating powder is evenly coated on the second perlite particles; thus obtaining type A third perlite particles.

[0021] The weighed ceramic-coated powder is added to a granulator containing type A third perlite particles and is in operation, so that the ceramic-coated powder is uniformly coated on the type A third perlite particles; thus obtaining type B third perlite particles.

[0022] Alternatively, the term "completely uniformly coated" means that when the coating is completed, the coating powder does not exist independently, but is completely coated on the surface of the perlite particles, with a dense texture and a tendency to be spherical; wherein, when the coating component powder exists independently, water is sprayed onto the perlite particles using a sprayer until the coating component powder is completely coated on the perlite particles and no particles stick together.

[0023] Alternatively, the method for preparing the vitreous coated powder in step 3) includes:

[0024] Sodium / potassium feldspar, perlite-like ore powder smaller than 100 mesh produced in step 1), borax, and boric acid are mixed in a mass ratio of (25-40):(40-60):(5-10):(0-5), and obtained by selective crushing, mixing and grinding. The particle size of the glassy coated powder is -200 mesh to -600 mesh.

[0025] Alternatively, the method for preparing the porcelain-coated powder includes: mixing perlite-like mineral powder (smaller than 100 mesh), sodium / potassium feldspar, kaolin, and quartz sand produced in the pretreatment in step 1) in a mass ratio of (10-30):(20-40):(20-30):(10-20), and obtaining the powder after selective crushing, mixing, and grinding. The particle size of the porcelain-coated powder is -200 mesh to -600 mesh.

[0026] Alternatively, the drying described in step 4) is a drying process of type B third perlite particles in a drying-preheating device, where the temperature is increased from the ambient temperature section to a drying section of 200-300°C at a heating rate of 8°C to 20°C.

[0027] Alternatively, the preheating treatment is a process in which the third type of perlite particles are preheated in a drying-preheating device by heating the drying section to a heating section at a rate of 50°C to 80°C to 500°C to 850°C; the fourth type of perlite particles have a moisture content of 2 to 3%.

[0028] Optionally, the high-temperature expansion treatment in step 5) includes: uniformly sprinkling the fourth perlite particles while they are still hot onto a high-temperature flame in an expansion furnace where the temperature is maintained at 1100-1250°C, or uniformly spreading the fourth perlite particles and directly feeding them into a high-temperature section in an electrically heated expansion furnace where the temperature is maintained at 1100-1350°C, so that the fourth perlite particles are rapidly heated and expand quickly.

[0029] The fourth perlite particle's residence time in the high-temperature flame or the high-temperature section of the electric heating furnace, i.e., the rapid expansion time, is 2s to 80s, to obtain the porcelain-shell expanded perlite.

[0030] In another aspect, the present invention provides a ceramic-shell expanded perlite, which can be prepared by the above method.

[0031] Optionally, the expanded perlite with a ceramic outer shell has a shell / core composite structure, with an outer shell and an inner core; wherein, the inner layer of the shell is a molten glass layer of glassy shelling components with a thickness of 0.02-0.1 mm; the outer layer of the shell is a ceramic layer sintered from the ceramic shelling components with a thickness of 0.2 mm-0.5 mm; the core is the expanded product of the first perlite particles, and the diameter of the core is determined by the size and expansion ratio of the first perlite particles, ranging from 1.5 mm to 28 mm; the bonding between the inner layer of the shell, the core, and the outer layer of the shell is a gradient bonding relationship of mutual penetration of components during the sintering-melting-expansion process.

[0032] The outer shell of the expanded perlite with a ceramic outer shell is mainly composed of a ceramic outer shell formed by sintering the coating ceramic shell components.

[0033] Alternatively, the expanded perlite with the porcelain-like outer shell may have the following properties: an expansion ratio of 4.2 to 7.5; and a bulk density of 220 to 320 kg / m³. 3 The compressive strength of the cylinder is 0.9–2.3 MPa; the thermal conductivity is 0.045–0.065 W / (m·K); the water absorption rate is less than 1.3%; the acid corrosion rate is less than 5%; and the alkali corrosion rate is less than 1%.

[0034] In another aspect, the present invention provides an application of expanded perlite with a porcelain shell, wherein the expanded perlite with a porcelain shell is the expanded perlite mentioned above.

[0035] Alternatively, the ceramic-shell expanded perlite mentioned above; the applications include the production of lightweight materials, thermal insulation materials, sound-absorbing and sound-insulating materials, decorative materials and fire-retardant materials, as well as its use as a substitute for cenospheres, lightweight and expanded ceramsite.

[0036] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0037] (1) The ceramic shell expanded perlite prepared by the present invention has a shell / core composite structure and has excellent properties such as high expansion ratio and mechanical strength, low bulk density and thermal conductivity, low water absorption and acid and alkali resistance. In addition, it has better lightweight, heat insulation, sound insulation and sound absorption process properties.

[0038] (2) The shell / core structure expanded perlite prepared by the present invention has a high degree of sphericity after coating and granulation treatment, and the outer shell is a ceramic material with higher strength. It can replace ceramsite, cenospheres, glass microspheres, etc.

[0039] (3) The glassy coating powder of the inner shell of the expanded perlite prepared by the present invention has a lower melting temperature than the expansion temperature of the perlite ore particles. That is, the glassy coating powder is melted before the perlite ore particles expand during the calcination process, which can effectively trap the gas generated when the perlite ore particles expand and increase the expansion ratio of the expanded perlite. After cooling, it forms closed-cell expanded perlite.

[0040] (4) The ceramic coating powder of the shell / core structure expanded perlite shell prepared in this invention is sintered into a ceramic body during the expansion process of the calcined perlite ore particles, forming a ceramic material coating layer on the outer surface of the expanded perlite. This ceramic outer shell coating layer has a higher bonding strength with organic binders and inorganic cementitious materials than the glassy outer shell coating layer in the process of preparing expanded perlite composite materials, which is of great significance for the preparation of high-strength expanded perlite composite materials.

[0041] (5) The shell / core structure expanded perlite prepared by this invention not only has closed-cell expanded perlite with sealed surface pores compared to ordinary expanded perlite, but also has higher sphericity and is easier to form a denser aggregate. These characteristics allow for a significant reduction in the amount of organic binders or inorganic cementitious materials required in the preparation of expanded perlite composite materials. This not only reduces production costs but also significantly improves the thermal insulation, sound insulation, and sound absorption properties of expanded perlite composite materials by reducing the amount of organic binders or inorganic cementitious materials (such as cement).

[0042] (6) The unique design of the ceramic-shell expanded perlite prepared in this invention effectively seals the internal pores, thereby reducing the adsorption of moisture and humidity by the expanded perlite material, thus ensuring the material's lightweight properties and excellent thermal insulation and sound absorption performance. Therefore, composite materials or products prepared using ceramic-shell expanded perlite with a shell / core structure have superior technological performance, and their application prospects are particularly broad in contemporary society that pursues high efficiency, energy saving, and environmental protection.

[0043] (7) The expanded perlite with a ceramic shell / core composite structure prepared by the present invention also has particularly excellent mechanical strength, high surface hardness and good bonding with organic binders or inorganic cementitious material matrices; in the production, transportation, composite material and product preparation and use process, compared with ordinary expanded perlite, almost no dust is generated, and the production, transportation and storage environment is pollution-free. Attached Figure Description

[0044] The above and other objects and / or features of the present invention will become clearer from the following description taken in conjunction with the accompanying drawings, in which:

[0045] Figure 1 A flowchart illustrating the preparation process of the expanded perlite with a ceramic outer shell as described in this invention is shown.

[0046] Figure 2 A photograph of traditional expanded perlite is shown.

[0047] Figure 3 A photograph of the expanded perlite with a ceramic shell as described in this invention is shown.

[0048] Figure 4 An optical microscope image of conventional expanded perlite is shown.

[0049] Figure 5 An electron microscope image of conventional expanded perlite is shown.

[0050] Figure 6 An optical microscope image of the expanded perlite with a ceramic shell as described in this invention is shown.

[0051] Figure 7 An electron microscope image of the expanded perlite with a ceramic shell as described in this invention is shown. Detailed Implementation

[0052] In the following description, an expanded perlite with a ceramic shell, its preparation method, and its application will be explained in detail with reference to exemplary embodiments.

[0053] It should be noted that terms such as "first," "second," "third," and "fourth" are merely for ease of description and distinction, and should not be interpreted as indicating or implying relative importance. Terms such as "up," "down," "front," "back," "left," "right," "inner," and "outer" are merely for ease of description and to establish relative orientations or positional relationships, and do not indicate or imply that the component referred to must have that specific orientation or position.

[0054] Exemplary Example 1

[0055] This exemplary embodiment provides a method for preparing expanded perlite with a porcelain outer shell, the method comprising:

[0056] S1. Pre-treat perlite ore to obtain the first perlite particles.

[0057] In this embodiment, the perlite ore includes one or more of four types of ore: perlite type, obsidian type, resinstone type, and pumice perlite.

[0058] In this embodiment, the pretreatment includes crushing, screening, and dust removal; the crushing is a crushing process with an inspection screening section, which further crushes the coarse perlite ore on the inspection screening screen to avoid over-crushing of perlite ore; the screening and dust removal include separating the crushed perlite ore into different particle sizes using a screening method, and collecting the micro powder with a particle size of less than 100 mesh from the perlite ore for use as raw material for preparing coating powder.

[0059] In this embodiment, the first perlite particles are perlite ore sand with a particle size range of +100 mesh to -10 mesh; the particle size specifications of the first perlite particles include multiple types from -10 mesh to +20 mesh, -20 mesh to +30 mesh, -30 mesh to +50 mesh, -50 mesh to +80 mesh, and -80 mesh to +100 mesh.

[0060] S2. Mix the first perlite particles and the binder according to the mass ratio and mix them evenly to obtain the second perlite particles.

[0061] In this embodiment, the mass ratio is 100:(4-9), such as 100:4, 100:4.5, 100:5, 100:6.8, 100:8.2 and 100:8.9.

[0062] In this embodiment, the uniform mixing includes: spraying the binder onto the first perlite particles being stirred using a spraying method, and uniformly coating the surface of the first perlite particles with the binder;

[0063] The second perlite particle is a perlite particle with a binder coated on its surface.

[0064] In this embodiment, the adhesive includes one or more of inorganic and organic adhesives in an aqueous solution or hydrosol prepared with water;

[0065] The inorganic binder comprises one or more of water glass, sodium silicate, and potassium silicate with a modulus of 1.0 to 2.9, and is prepared as an aqueous solution with a density of 1.36 to 1.50 g / cm3 and a Baume degree of 38.4 to 48.3.

[0066] The organic binder includes one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, acrylic emulsion, vinyl acetate emulsion, polyvinyl alcohol acetal, emulsion glue, animal glue, and plant glue, and is formulated into a water-soluble adhesive with a solid content of 0.5% to 2.0% by mass.

[0067] S3. Glassy coating powder and ceramic coating powder are added to the second perlite particles in sequence for granulation to obtain type A third perlite particles and type B third perlite particles in sequence.

[0068] In this embodiment, the granulation process involves first mixing the glassy coating component powder with second perlite particles and bonding them with a surface binder of the perlite particles to form a glassy coating layer, then adding ceramic coating powder to continue granulation and form a ceramic coating layer. The granulation process includes:

[0069] Weigh the second perlite particles, glassy coating powder and ceramic coating powder in a mass ratio of (76-84):(5-9):(11-15), such as 76:5:11, 80:5.5:12, 81.5:7:12.5 and 83.5:8.2:14.5, etc.

[0070] The weighed second perlite particles are placed in a granulator, and then the weighed glassy coating powder is evenly added to the running granulator so that the glassy coating powder is evenly coated on the second perlite particles; thus obtaining composite particles of glassy coating component / second perlite particles, namely type A third perlite particles.

[0071] The weighed ceramic-coated powder is added to a granulator containing type A third perlite particles and is in operation, so that the ceramic-coated powder is uniformly coated on the type A third perlite particles; thus, composite particles of ceramic-coated component / glassy-coated component / second perlite particles with a smooth surface are obtained, namely type B third perlite particles.

[0072] In this embodiment, "complete and uniform coating" means that when the coating is completed, the coating powder does not exist independently, but is completely coated on the surface of the perlite particles, with a dense texture and a tendency to be spherical. When the coating component powder exists independently, water is sprayed onto the perlite particles using a sprayer until the coating component powder is completely coated on the perlite particles and no particles stick together.

[0073] In this embodiment, the method for preparing the vitreous coating powder in step 3) includes:

[0074] Sodium / potassium feldspar, perlite-like ore powder smaller than 100 mesh produced in step 1), borax, and boric acid are mixed in a mass ratio of (25-40):(40-60):(5-10):(0-5), such as 25:40:5:0.5, 30:42:6.5:1.2, 36:45:8:2.5, and 39.5:59:9.5:4.8, etc.; and obtained by selective crushing, mixing and grinding. The particle size of the glassy coated powder is -200 mesh to -600 mesh.

[0075] In this embodiment, the method for preparing the porcelain-coated powder includes: mixing perlite-like ore powder (smaller than 100 mesh), sodium / potassium feldspar, kaolin, and quartz sand produced in the pretreatment in step 1) in a mass ratio of (10-30):(20-40):(20-30):(10-20), such as 10:20:20:10, 16:25:24.5:14, 21:28:26:15.5, and 29:38.5:29:18; and obtaining the porcelain-coated powder after selective crushing, mixing, and grinding. The particle size of the porcelain-coated powder is -200 mesh to -600 mesh.

[0076] S4. Dry and preheat the type B third perlite particles to obtain preheated fourth perlite particles.

[0077] In this embodiment, the drying process described herein is the drying process of type B third perlite particles in a drying-preheating device, where the temperature is increased from the ambient temperature section to a drying section of 200-300°C at a heating rate of 8°C to 20°C.

[0078] In this embodiment, the preheating treatment is a process in which the B-type third perlite particles are preheated in the drying-preheating device by heating the drying section to a heating section of 500-850°C at a heating rate of 50°C-80°C; during the drying-preheating process, the airflow in the drying-preheating device automatically flows from the heating section to the room temperature section; the moisture content of the fourth perlite particles is 2-3%.

[0079] Drying and preheating are essential steps in the process. Drying reduces the surface moisture of the perlite particles, while preheating reduces the internal moisture. Without these processes, excessive moisture on the surface and inside the perlite particles will cause them to absorb a large amount of heat during expansion due to excessive evaporation. This reduces the temperature difference required for rapid heating and prolongs the expansion time, preventing the perlite from expanding instantly and affecting its expansion ratio. Conversely, preheating increases the temperature of the material before the perlite particles enter the expansion furnace, allowing them to quickly reach their expansion temperature and expand instantly, thus increasing the expansion ratio.

[0080] S5. The preheated fourth perlite particles are subjected to high-temperature expansion treatment to obtain expanded perlite with a porcelain shell.

[0081] In this embodiment, the high-temperature expansion treatment includes: uniformly sprinkling the fourth perlite particles while they are still hot onto a high-temperature flame in an expansion furnace where the temperature is maintained at 1100-1250°C, or uniformly spreading the fourth perlite particles and directly feeding them into a high-temperature section in an electrically heated expansion furnace where the temperature is maintained at 1100-1350°C, so that the fourth perlite particles are rapidly heated and expand quickly.

[0082] The fourth perlite particle's residence time in the high-temperature flame or the high-temperature section of the electric heating furnace, i.e., the rapid expansion time, is 2s to 80s, to obtain the porcelain-shell expanded perlite.

[0083] In this embodiment, during the high-temperature expansion process, the glassy coating powder material covering the outer surface of the first perlite ore particles melts first, forming a viscous glassy melt that coats the perlite particles. This viscous glassy melt coating layer thins into a continuous coating layer as the first perlite particles rapidly expand, simultaneously trapping the gas released during the expansion of the first perlite particles and significantly increasing the expansion ratio of the expanded perlite. Meanwhile, the ceramic coating component covering the surface of the glassy coating powder material is sintered into a ceramic shell under high-temperature conditions without melting. This non-melting sintered layer better prevents the adhesion between the expanded perlite particles. The result is not only expanded perlite with a ceramic shell, but also expanded perlite with a closed-cell ceramic shell.

[0084] Exemplary Example 2

[0085] This exemplary embodiment provides a ceramic-shell expanded perlite, which can be prepared by the method described in Exemplary Embodiment 1.

[0086] The expanded perlite with a porcelain shell has a shell / core composite structure, with an outer shell and an inner core. The inner layer of the shell is a molten glass layer of glassy coating components, with a thickness of 0.02–0.1 mm. The outer layer of the shell is a porcelain layer sintered from the porcelain coating components, with a thickness of 0.2 mm–0.5 mm. The core is the expanded product of the first perlite particles, and the diameter of the core is determined by the size of the first perlite particles and the expansion ratio, ranging from 1.5 mm to 28 mm. The bonding between the inner layer of the shell, the core, and the outer layer of the shell is a gradient bonding relationship of mutual penetration of components during the sintering-melting-expansion process.

[0087] The outer shell of the expanded perlite with a ceramic outer shell is mainly composed of a ceramic outer shell formed by sintering the coating ceramic shell components.

[0088] In this embodiment, the expanded perlite with a porcelain outer shell has the following properties: an expansion ratio of 4.2 to 7.5; a bulk density of 220 to 320 kg / m³; a cylinder compressive strength of 0.9 to 2.3 MPa; a thermal conductivity of 0.045 to 0.065 W / (m·K); a water absorption rate of less than 1.3%; an acid etching rate of less than 5%; and an alkali etching rate of less than 1%.

[0089] To better demonstrate the characteristics of the product of this invention, the applicant has provided, as follows: Figure 2 , Figure 4 , Figure 5 The images shown are photographs of ordinary expanded perlite, optical microscope images, and electron microscope images, and also include images of... Figure 3 , Figure 6 , Figure 7 The photographs shown are optical microscope images and electron microscope images of the expanded perlite with a ceramic shell according to the present invention. Figure 2 Ordinary expanded perlite is uncoated expanded perlite.

[0090] from Figure 2 and Figure 3 It can be observed that traditional expanded perlite particles obtained by conventional methods have low sphericity, while the expanded perlite with a porcelain-like outer shell prepared by this invention has high sphericity; from Figure 4 and Figure 5 It can be observed that the surface of traditional expanded perlite contains pores and voids formed by the escape of gas during the expansion process, resulting in an uneven surface with sharp edges. Therefore, these pores easily absorb binders (such as cement paste, water glass, etc.).

[0091] from Figure 6 and Figure 7 It can be observed that the vitreous inner layer and porcelain outer layer of the ceramic expanded perlite shell prepared by this invention encapsulate the surface of the expanded perlite, sealing its pores. Therefore, it possesses excellent moisture-proof, waterproof, thermal insulation, and sound-absorbing properties. The porcelain outer layer, because it did not melt during the high-temperature expansion process to form a cracked sintered layer, facilitates a strong bond with the adhesive.

[0092] Exemplary Example 3

[0093] This exemplary embodiment provides an application of expanded perlite with a porcelain shell, wherein the expanded perlite with a porcelain shell is the expanded perlite described in Exemplary Embodiment 2.

[0094] In this embodiment, the applications include the production of lightweight materials, thermal insulation materials, sound-absorbing and sound-insulating materials, decorative materials, and fire-retardant materials, as well as their use as a substitute for cenospheres, lightweight materials, and expanded ceramsite.

[0095] To better understand the exemplary embodiments of the present invention described above, further explanation is provided below with reference to specific examples.

[0096] Example 1

[0097] A ceramic-shell expanded perlite and its preparation and application methods, such as Figure 1 As shown, the preparation method includes the following steps:

[0098] (1) Pre-treat the perlite ore, i.e. crush, screen and remove dust to obtain the first perlite particles.

[0099] (2) Select first-grade perlite particles with a mesh size of -10 to +20, and choose a binder with a modulus of 1.0 and a density of 1.36 g / cm³. 3 A potassium silicate adhesive aqueous solution with a Baume degree of 38.4 was prepared. The first perlite particles and the binder were mixed at a mass ratio of 100:6. The binder was sprayed onto the surface of the first perlite particles using a spray gun and mixed evenly to obtain the second perlite particles.

[0100] (3) The pre-treated micro powder (smaller than 100 mesh), ordinary silicate waste glass, borax, and boric acid are mixed in a mass percentage ratio of 30:55:10:5, and then subjected to selective crushing and mixed grinding to obtain glassy coated powder. The particle size of the glassy coated powder is -500 mesh to +600 mesh. The pre-treated micro powder (smaller than 100 mesh), feldspar, kaolin, and quartz sand are mixed in a mass percentage ratio of 20:40:30:10, and then subjected to selective crushing and mixed grinding to obtain porcelain coated powder. The particle size of the porcelain coated powder is -400 mesh to +500 mesh. Then, according to the mass ratio of the second perlite particles, glassy coated powder, and porcelain coated powder, the second perlite and glassy coated powder are added to the granulator and then granulated to obtain type A third perlite particles. During the granulation process of type A perlite particles, ceramic-coated powder is added simultaneously to ultimately obtain type B third perlite particles.

[0101] (4) The third type of perlite particles of type B were placed in a drying device and heated to 220°C at a heating rate of 12°C / min for drying. Then they were placed in a preheating device and heated to 750°C at a heating rate of 65°C. They were then preheated at this temperature for 8 minutes to obtain the fourth type of perlite particles with a water content of 2.4%.

[0102] (5) The preheated fourth perlite particles are evenly spread out and directly fed into a flame expansion furnace maintained at 1200℃ for high-temperature expansion treatment. The expansion time is 15s, which causes the fourth perlite particles to be rapidly heated and expanded, thus obtaining the porcelain-shell expanded perlite. The obtained porcelain-shell expanded perlite has excellent moisture-proof, waterproof, thermal insulation, and sound absorption properties, with a bulk density of 220kg / m³. 3 The compressive strength of the cylinder is 1.0 MPa; the thermal conductivity is 0.063 W / (m·K); the water absorption rate is 1.21%; the acid etching rate is 4.23%; and the alkaline etching rate is 0.66%.

[0103] Example 2

[0104] A ceramic-shell expanded perlite and its preparation and application methods include the following steps:

[0105] (1) Pre-process the obsidian-type ore, namely crushing, screening and dust removal, to obtain the first perlite particles.

[0106] (2) Select first-grade perlite particles of -30 mesh to +50 mesh, and choose a binder with a modulus of 2.0 and a density of 1.50 g / cm³. 3 A potassium silicate adhesive aqueous solution with a Baume degree of 48.3 was prepared. The first perlite particles and the binder were mixed at a mass ratio of 100:9. The binder was sprayed onto the surface of the first perlite particles using a spray gun and mixed evenly to obtain the second perlite particles.

[0107] (3) The pre-treated micro powder (smaller than 100 mesh), ordinary silicate waste glass, borax, and boric acid are mixed in a mass percentage ratio of 40:55:0:5, and then selectively crushed and mixed-grinded to obtain a glassy coating powder with a particle size of -325 mesh to +400 mesh. The pre-treated micro powder (smaller than 100 mesh), feldspar, kaolin, and quartz sand are mixed in a mass percentage ratio of 10:40:30:20, and then selectively crushed and mixed-grinded to obtain a ceramic coating powder with a particle size of -325 mesh to +400 mesh. Then, according to the mass ratio of the second perlite particles, glassy coating powder, and ceramic coating powder, the second perlite and glassy coating powder are added to a granulator and then granulated to obtain type A third perlite particles. During the granulation process of type A perlite particles, ceramic-coated powder is added simultaneously to ultimately obtain type B third perlite particles.

[0108] (4) Place the third type of perlite particles in a drying device and heat them to 200°C at a heating rate of 8°C / min. Then place them in a preheating device and heat them to 850°C at a heating rate of 70°C. Preheat them at this temperature for 14 minutes to obtain the fourth type of perlite particles with a water content of 2.0%.

[0109] (5) The preheated fourth perlite particles are evenly spread out and directly fed into an electrically heated expansion furnace maintained at 1100℃ for high-temperature expansion treatment. The expansion time is 40s, which causes the fourth perlite particles to be rapidly heated and expanded to obtain the porcelain-shell expanded perlite. The obtained porcelain-shell expanded perlite has excellent moisture-proof, waterproof, thermal insulation, and sound absorption properties, with a bulk density of 320kg / m³. 3 The compressive strength of the cylinder is 1.8 MPa; the thermal conductivity is 0.046 W / (m·K); the water absorption rate is 0.87%; the acid etching rate is 2.79%; and the alkali etching rate is 0.41%.

[0110] Example 3

[0111] (1) Pre-treat the pumice-shaped ore, i.e. crush, screen and remove dust to obtain the first perlite particles.

[0112] (2) Select first-grade perlite particles of -20 mesh to +30 mesh, and choose a binder with a modulus of 2.9 and a density of 1.42 g / cm³. 3 A potassium silicate adhesive aqueous solution with a Baume degree of 42.3 was prepared. The first perlite particles and the binder were mixed at a mass ratio of 100:4. The binder was sprayed onto the surface of the first perlite particles using a spray gun and mixed evenly to obtain the second perlite particles.

[0113] (3) The pre-treated micro powder (smaller than 100 mesh), ordinary silicate waste glass, borax, and boric acid are mixed in a mass percentage ratio of 25:60:10:5, and then subjected to selective crushing and mixed grinding to obtain glassy coated powder. The particle size of the glassy coated powder is -400 mesh to +500 mesh. The pre-treated micro powder (smaller than 100 mesh), feldspar, kaolin, and quartz sand are mixed in a mass percentage ratio of 30:30:25:15, and then subjected to selective crushing and mixed grinding to obtain porcelain coated powder. The particle size of the porcelain coated powder is -500 mesh to +600 mesh. Then, according to the mass ratio of the second perlite particles, glassy coated powder, and porcelain coated powder, the second perlite and glassy coated powder are added to the granulator and then granulated to obtain type A third perlite particles. During the granulation process of type A perlite particles, ceramic-coated powder is added simultaneously to ultimately obtain type B third perlite particles.

[0114] (4) Place the third type of perlite particles in a drying device and heat them to 250°C at a heating rate of 15°C / min for drying. Then place them in a preheating device and heat them to 680°C at a heating rate of 50°C. Preheat them at this temperature for 10 minutes to obtain the fourth type of perlite particles with a water content of 2.8%.

[0115] (5) The preheated fourth perlite particles are evenly spread out and directly fed into an electrically heated expansion furnace maintained at 1250℃ for high-temperature expansion treatment. The expansion time is 20s, which causes the fourth perlite particles to be rapidly heated and expanded, thus obtaining the porcelain-shell expanded perlite. The obtained porcelain-shell expanded perlite has excellent moisture-proof, waterproof, thermal insulation, and sound absorption properties, with a bulk density of 280kg / m³. 3 The compressive strength of the cylinder is 2.2 MPa; the thermal conductivity is 0.053 W / (m·K); the water absorption rate is 1.01%; the acid etching rate is 3.97%; and the alkali etching rate is 0.59%.

[0116] Table 1 shows the preparation parameters for the porcelain-shell expanded perlite prepared in Example 4-7; Table 2 shows the parameters for the drying, preheating, and thermal expansion processes in Example 4-7; and Table 3 shows the characteristics of the porcelain-shell expanded perlite prepared in Example 4-7. From the parameters in Tables 1-3, it can be seen that the porcelain-shell expanded perlite prepared in Example 4-7 expands by 4.35 to 6.8 times, with a bulk density of 237 to 311 kg / m³. 3 The cylinder compressive strength is 1.8–2.3 MPa, the thermal conductivity is 0.045–0.051 W / (m·K), the water absorption rate is 0.82%–1.11%, the acid corrosion rate is 2.6%–4.15%, and the alkali corrosion rate is 0.23%–0.67%.

[0117] Example 4

[0118] The overall process flow and raw material selection in this example are the same as in Example 1. The process parameters involved are shown in Tables 1 and 2, and the performance parameters of the resulting product are shown in Table 3.

[0119] Example 5

[0120] The overall process flow and raw material selection in this example are the same as in Example 1. The process parameters involved are shown in Tables 1 and 2, and the performance parameters of the resulting product are shown in Table 3.

[0121] Example 6

[0122] The overall process flow and raw material selection in this example are the same as in Example 1. The process parameters involved are shown in Tables 1 and 2, and the performance parameters of the resulting product are shown in Table 3.

[0123] Example 7

[0124] The overall process flow and raw material selection in this example are the same as in Example 1. The process parameters involved are shown in Tables 1 and 2, and the performance parameters of the resulting product are shown in Table 3.

[0125] Table 1. Process parameters involved in the preparation of Example 4-7

[0126]

[0127] Table 2 Parameters of the drying, preheating and thermal expansion processes in Example 4-7 of the preparation

[0128]

[0129] Table 3 Properties of expanded perlite with porcelain shell prepared in Example 4-7

[0130]

[0131] Although the present invention has been described above in conjunction with exemplary embodiments and accompanying drawings, those skilled in the art should understand that various modifications can be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. A method for preparing expanded perlite with a porcelain-like outer shell, characterized in that, The preparation method includes: 1) Pre-treat perlite ore to obtain the first perlite particles; 2) Mix the first perlite particles and the binder according to the mass ratio and mix them evenly to obtain the second perlite particles; 3) Glassy coating powder and ceramic coating powder are added to the second perlite particles in sequence for granulation to obtain type A third perlite particles and type B third perlite particles in sequence. 4) The type B third perlite particles are dried and preheated to obtain preheated fourth perlite particles; 5) The preheated fourth perlite particles are subjected to high-temperature expansion treatment to obtain expanded perlite with a porcelain shell.

2. The method for preparing expanded perlite with a porcelain outer shell according to claim 1, characterized in that, The perlite ore includes one or more of four types of ore: perlite type, obsidian type, pitchstone type, and pumice perlite. The pretreatment includes crushing, screening, and dust removal; the crushing is crushing with a screening section for inspection; the screening and dust removal include separating the crushed perlite sand into different particle sizes by screening, and collecting the micro powder with a particle size of less than 100 mesh from the perlite sand for use as raw material for preparing coating powder.

3. The method for preparing expanded perlite with a porcelain outer shell according to claim 1, characterized in that, The mass ratio mentioned in step 2) is 100:(4-9); The uniform mixing includes: spraying the binder onto the first perlite particles being stirred using a spraying method, and uniformly coating the surface of the first perlite particles with the binder to obtain the second perlite particles.

4. The method for preparing expanded perlite with a porcelain outer shell according to claim 1, characterized in that, The adhesive includes one or more of inorganic and organic adhesives in aqueous solutions or hydrosols prepared with water; The inorganic binder comprises one or more of water glass, sodium silicate, and potassium silicate with a modulus of 1.0 to 2.9, and is configured to have a density of 1.36 to 1.50 g / cm³. 3 The aqueous solution has a Baumé degree of 38.4–48.3; The organic binder includes one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, acrylic emulsion, vinyl acetate emulsion, polyvinyl alcohol acetal, emulsion glue, animal glue, and plant glue, and is formulated into a water-soluble adhesive with a solid content of 0.5% to 2.0% by mass.

5. The method for preparing expanded perlite with a porcelain outer shell according to claim 1, characterized in that, The granulation process described in step 3) involves first mixing the glassy coating component powder with the second perlite particles and then bonding them with a surface binder of the perlite particles to form a glassy coating layer. Then, ceramic coating powder is added to continue granulation and form a ceramic coating layer. The granulation process includes: Weigh the second perlite particles, glassy coating powder, and ceramic coating powder in a mass ratio of (76-84):(5-9):(11-15); The weighed second perlite particles are placed in a granulator, and then the weighed glassy coating powder is evenly added to the running granulator so that the glassy coating powder is evenly coated on the second perlite particles; thus obtaining type A third perlite particles. The weighed ceramic-coated powder is added to a granulator containing type A third perlite particles and is in operation, so that the ceramic-coated powder is uniformly coated on the type A third perlite particles; thus obtaining type B third perlite particles.

6. The method for preparing expanded perlite with a porcelain outer shell according to claim 1, characterized in that, The preparation method of the vitreous coated powder in step 3) includes: Sodium / potassium feldspar, perlite-like ore powder smaller than 100 mesh produced in step 1), borax, and boric acid are mixed in a mass ratio of (25-40):(40-60):(5-10):(0-5), and obtained by selective crushing, mixing and grinding. The particle size of the glassy coated powder is -200 mesh to -600 mesh. The method for preparing the porcelain-coated powder includes: mixing perlite-like mineral powder (smaller than 100 mesh), sodium / potassium feldspar, kaolin, and quartz sand produced in the pretreatment in step 1) in a mass ratio of (10-30):(20-40):(20-30):(10-20), and then selectively crushing, mixing, and grinding the powder to obtain the porcelain-coated powder with a particle size of -200 mesh to -600 mesh.

7. The method for preparing expanded perlite with a porcelain outer shell according to claim 1, characterized in that, The drying process described in step 4) is the drying process of type B third perlite particles in a drying-preheating device, where the temperature is increased from the ambient temperature section to the drying section at a rate of 8℃~20℃ to 200~300℃. The preheating treatment is a process in which the third type of perlite particles are preheated in a drying-preheating device by heating the drying section to a heating section at a rate of 50°C to 80°C to 500°C to 850°C; the fourth type of perlite particles have a moisture content of 2 to 3%.

8. The method for preparing expanded perlite with a porcelain outer shell according to claim 1, characterized in that, The high-temperature expansion treatment in step 5) includes: while the fourth perlite particles are still hot, they are evenly sprinkled onto a high-temperature flame in an expansion furnace where the temperature is maintained at 1100-1250°C; or, the fourth perlite particles are evenly spread out and directly fed into a high-temperature section in an electrically heated expansion furnace where the temperature is maintained at 1100-1350°C, so that the fourth perlite particles are rapidly heated and expand quickly. The fourth perlite particle's residence time in the high-temperature flame or the high-temperature section of the electric heating furnace, i.e., the rapid expansion time, is 2s to 80s, to obtain the porcelain-shell expanded perlite.

9. A type of expanded perlite with a porcelain-like outer shell, characterized in that, The porcelain-shell expanded perlite is obtained by the method described in any one of claims 1-8; the porcelain-shell expanded perlite has a shell / core composite structure, with an outer shell and an inner core, wherein... The inner layer of the shell is a molten glass layer of glassy cladding components with a thickness of 0.02 to 0.1 mm; the outer layer of the shell is a ceramic layer sintered from ceramic cladding components with a thickness of 0.2 mm to 0.5 mm. The core is the expansion product of the first perlite particle, and the diameter of the core is determined by the size of the first perlite particle and the expansion ratio, with a diameter range of 1.5 mm to 28 mm. The combination of the shell and the core is a gradient bonding relationship of mutual penetration of components during the sintering-melting-expansion process.

10. The expanded perlite with a porcelain outer shell according to claim 9, characterized in that, The properties of the expanded perlite with a porcelain outer shell include: The expansion ratio is 4.2 to 7.5; Bulk density is 220–320 kg / m³ 3 ; The compressive strength of the cylinder is 0.9–2.3 MPa; The thermal conductivity is 0.045–0.065 W / (m·K); Water absorption rate is less than 1.3%; The acid etching amount is less than 5%; The alkaline corrosion rate is less than 1%.

11. An application of expanded perlite with a porcelain-like outer shell, characterized in that, The expanded perlite with a ceramic shell is the expanded perlite with a ceramic shell as described in claim 9; the applications include the production of lightweight materials, thermal insulation materials, sound-absorbing and sound-insulating materials, decorative materials and fire-retardant materials, as well as its use as a substitute for cenospheres, lightweight materials and expanded ceramsite.

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