Ultra-light foamed ceramic hollow sphere prepared from iron lepidolite tailings as well as preparation method and application of ultra-light foamed ceramic hollow sphere

Abstract

The invention relates to the technical field, in particular to an ultralight foamed ceramic hollow sphere prepared from iron lepidolite tailings and a preparation method and application of the ultralight foamed ceramic hollow sphere. The foamed ceramic hollow sphere is prepared from the following raw materials: iron lepidolite tailings, silicon carbide, bentonite, sodium carbonate and potassium carbonate; in percentage by mass, the content of the iron lepidolite tailings is 90 to 96.4 percent; the content of the silicon carbide is 0.1-1%; the iron lepidolite tailings are prepared from the following components in percentage by mass: 77 to 80 percent of SiO2, 10 to 13 percent of Al2O3, 1.3 to 1.6 percent of Fe2O3 and 0.1 to 0.17 percent of Li2O. The ultralight foamed ceramic hollow sphere is prepared by using the iron lepidolite tailings, the silicon carbide, the bentonite, the sodium carbonate and the potassium carbonate as raw materials, can meet various market requirements of heat preservation, heat insulation, sound insulation, noise reduction and the like, and brings remarkable economic benefits and social benefits.

Description

Technical Field

[0001] The present invention relates to the technical field, and in particular to an ultra-light foam ceramic hollow sphere prepared by utilizing lithophile mica tailings, and a preparation method and application thereof. Background Art

[0002] The mining and smelting processes of lithium ore inevitably generate large quantities of lithium tailings. These tailings are typically the solid waste remaining after the extraction of primary lithium-containing minerals such as spodumene and lepidolite. Their primary chemical composition typically includes significant amounts of silicon dioxide (SiO2) and aluminum oxide (Al2O3), along with varying amounts of feldspar, quartz, and mica. They may also contain small amounts of oxides of elements such as iron, calcium, magnesium, sodium, and potassium, and sometimes trace amounts of unextracted lithium. Statistics show that for every ton of lithium carbonate or lithium hydroxide produced, several or even tens of tons of tailings are generated. Their storage not only consumes significant land resources but can also cause a range of environmental problems, including dust pollution, soil erosion, and the leaching of heavy metals and hazardous elements (such as fluorine) into surrounding soil and water.

[0003] Using industrial solid waste as raw materials is an effective way to reduce costs. The utilization of lithium tailings solid waste has been a research hotspot in recent years, but it still faces many defects and challenges: (1) Lithium tailings produced by different deposit types (such as pegmatite-type and salt lake-type associated solid waste) and different mineral processing processes have huge differences in chemical composition, mineral composition, particle size distribution, and harmful impurity content. This makes it difficult for one utilization technology to be universally applicable to all types of lithium tailings, and it is necessary to "adapt to the mine conditions", which increases the complexity of research and development and application. (2) High value-added utilization technology is not yet mature and the degree of industrialization is low. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the present invention provides an ultra-light foam ceramic hollow sphere prepared by utilizing lithophile mica tailings, and a preparation method and application thereof.

[0005] In a first aspect, the present invention provides a foam ceramic hollow sphere, wherein the raw materials of the foam ceramic hollow sphere include: iron lithium mica tailings, silicon carbide, bentonite, sodium carbonate and potassium carbonate; In percentage by mass, the content of the iron lithium mica tailings is 90 to 96.4%; the content of silicon carbide is 0.1 to 1%; In terms of mass percentage, the SiO2 in the iron lithium mica tailings is 77-80%, Al2O3 is 10-13%, Fe2O3 is 1.3-1.6%, and Li2O is 0.1-0.17%.

[0006] Ceramic hollow spheres are spherical hollow materials characterized by low density, low thermal conductivity, and high specific surface area. They are widely used in thermal insulation, sound absorption, catalyst support, adsorption, and other fields, and have broad market prospects. Currently, the main methods for producing ceramic hollow spheres include high-temperature melt foaming, spray drying, and template methods. High-temperature melt foaming consumes a lot of energy; spray drying results in difficult-to-control sphere cavity morphology; and template methods are complex, costly, and difficult to mass-produce.

[0007] The present invention uses iron lithium mica tailings as the main raw material, and is matched with silicon carbide, bentonite, sodium carbonate and potassium carbonate, and obtains a foam ceramic hollow ball with low density and high strength through molding and roasting process, wherein the iron lithium mica tailings have poor moldability and are difficult to form high-strength green balls alone. The use of bentonite as a binder can effectively improve the moldability and appropriately increase the strength of the green balls, making the green ball skeleton structure more stable and dense, providing a favorable environment for high-temperature foaming cavitation. The use of sodium carbonate and potassium carbonate composite additives not only effectively controls the amount of high-temperature liquid phase and its liquid phase viscosity, but also effectively regulates the high-temperature oxidation rate of silicon carbide, thereby controlling its foaming speed and foam stability in the aforementioned skeleton structure. The present invention is coordinated by formula design, molding pressure control and roasting temperature control, so that when the blank expands to the extreme, the barriers between the pores inside the ball disappear, forming an internal hollow structure, and finally obtaining low-density foam ceramic hollow balls.

[0008] Furthermore, in terms of mass percentage, the SiO2 in the iron lithium mica tailings is 77~80%, Al2O3 is 10~13%, K2O is 3.2~3.6%, Fe2O3 is 1.3~1.6%, MgO is 0.1~0.2%, Na2O is 0.5~0.7%, Li2O is 0.1~0.17%, and the loss on ignition is 1.9~2.2%.

[0009] Furthermore, the silicon carbide has a particle size of less than 20 μm and a purity greater than 85%; preferably, the silicon carbide is black silicon carbide powder and / or green silicon carbide powder.

[0010] Furthermore, in terms of mass percentage, the bentonite is 0.5-1%, and the total of the sodium carbonate and potassium carbonate is 3-8%.

[0011] Furthermore, the montmorillonite content in the bentonite is 55-80%, and the particle size is less than 45 μm; preferably, the bentonite is sodium-based bentonite and / or calcium-based bentonite.

[0012] Furthermore, in terms of molar ratio, the ratio of sodium carbonate to potassium carbonate is (1-3): (1-3).

[0013] Furthermore, the outer diameter of the hollow ceramic foam ball is 8-15 mm, the cavity diameter is 2-9 mm, and the bulk density is 240-400 kg / m 3 The cylinder pressure strength is 0.37~2.3MPa, the mass water absorption rate is 1.27%~5.6%, and the thermal conductivity coefficient is 0.079~0.11W / (m·K).

[0014] In a second aspect, the present invention provides a method for preparing the aforementioned hollow foam ceramic spheres, comprising: The iron lithium mica tailings, silicon carbide, bentonite, sodium carbonate and potassium carbonate are mixed and finely ground to obtain a mixture; Pressing the mixture into shapes to obtain green balls; The green balls are sequentially dried, preheated, calcined and cooled to obtain foamed ceramic hollow balls.

[0015] Furthermore, the pressing pressure is 5-20 MPa.

[0016] In the preparation of the aforementioned hollow ceramic foam spheres, molding pressure is one of the most critical processes. A specific pressure window promotes the formation of an optimal skeleton structure between the tailings matrix and the bentonite, while ensuring that other components such as silicon carbide, sodium carbonate, and potassium carbonate are evenly dispersed, rather than over-compacted or aggregated. This allows for more uniform cell nucleation and more controlled cell growth during subsequent heating, ultimately resulting in hollow ceramic foam spheres with a narrower pore size distribution, more complete pore walls, and a more ideal open / closed cell ratio.

[0017] Furthermore, the drying conditions include: drying temperature of 100-200° C., drying time of 5-10 minutes; and / or, The preheating conditions include: preheating temperature of 400-700°C, preheating time of 10-30 minutes; and / or, The calcination conditions include: a calcination temperature of 1100-1200° C. and a calcination time of 10-60 minutes.

[0018] 10. Use of the hollow ceramic foam sphere according to any one of claims 1 to 6 in any of the following applications: (1) Preparation of ultra-light aggregate; (2) Preparation of refractory materials; (3) Preparation of noise reduction materials; (4) Preparation of filtering or separation materials; (5) Preparation of catalyst supports or reactor materials; (6) Preparation of environmental remediation materials; (7) Preparation of electromagnetic functional materials.

[0019] The present invention has the following beneficial effects: The present invention proposes a new method for preparing foam ceramic hollow spheres at low cost. The method uses iron lithium mica tailings as the main raw material, and obtains new ultra-light foam ceramic hollow spheres through the coordinated control of raw material formula design, pressing molding pressure regulation and roasting system.

[0020] The novel ultra-light foam ceramic hollow spheres provided by the present invention can effectively increase the disposal capacity of lithophile mica tailings (by more than 90%), while also solving environmental problems and safety hazards such as the occupation of land resources by the storage of lithophile mica tailings, and reducing the production cost of the foam ceramic hollow spheres, thus bringing significant economic and social benefits.

[0021] The novel ultralight foam ceramic hollow spheres provided by the present invention not only meet the requirements of GBT17431.1-2010 standard for ultralight coarse aggregates for thermal insulation or structural thermal insulation, filling the gap in the high-strength ultralight coarse aggregate market, but can also be used in fields such as sound absorption and noise reduction, catalysis, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 This is a cross-sectional photograph of the ultralight hollow foam ceramic sphere provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0025] Unless otherwise specified, the experimental methods involved in the following examples are all conventional methods in the art. For example, reference can be made to experimental manuals in the art, or the conditions recommended by the manufacturer's instructions.

[0026] Unless otherwise specified, the experimental materials and reagents involved in the following examples can be obtained from commercial sources.

[0027] Example 1 This embodiment provides a method for producing ultralight hollow foam ceramic balls, and the specific steps are as follows: After drying the iron lithium mica tailings, the content of the iron lithium mica tailings is calculated as 92.5%, the content of silicon carbide is 0.5%, the content of bentonite is 1%, and the content of the sodium carbonate and potassium carbonate composite additive is 6% (the molar ratio of sodium carbonate and potassium carbonate is 3:1) according to the dry weight percentage of the mixture, and dry ball milling is performed to obtain a mixture. The mixture is dry pressed and formed, and the molding pressure is controlled to 10MPa to obtain green balls. The green balls are dried at 120℃ for 10 minutes; then preheated at 700℃ for 10 minutes; and then calcined at a calcination temperature of 1140℃ and a calcination time of 30 minutes. After the calcination is completed, it is naturally cooled to obtain ultra-light foam ceramic hollow balls (the cross-sectional photo of which is shown in the figure). Figure 1 shown).

[0028] After testing, the outer diameter of the ultra-light foam ceramic hollow ball is 15mm, the cavity diameter is 9mm, and the bulk density is 240kg / m 3 The 1h mass water absorption rate is 3.2%, the cylinder compressive strength is 0.89MPa, and the thermal conductivity is 0.079W / (m·K). According to the GBT17431-2010 standard, the cylinder compressive strength of ultra-light coarse aggregate with a density grade of 300 must be greater than 0.5MPa, so it meets the standard.

[0029] Example 2 This embodiment provides a method for producing ultralight hollow foam ceramic balls, and the specific steps are as follows: After drying the lithobite tailings, the mixture was weighed to have a dry weight percentage of 92.5% lithobite tailings, 0.5% silicon carbide, 1% bentonite, and 6% sodium carbonate and potassium carbonate (sodium carbonate:potassium carbonate molar ratio of 3:1). The mixture was dry-milled to obtain a mixture. The mixture was then dry-pressed at a pressure of 6 MPa to produce green balls. The green balls were dried at 120°C for 10 minutes, preheated at 700°C for 10 minutes, and then calcined at 1140°C for 30 minutes. After calcination, the mixture was allowed to cool naturally to obtain ultra-lightweight hollow foam ceramic balls.

[0030] After testing, the outer diameter of the ultra-light foam ceramic hollow ball is 15mm, the cavity diameter is 7.5mm, and the bulk density is 258kg / m 3 The 1h mass water absorption rate is 9.8%, the cylinder compressive strength is 1.1MPa, and the thermal conductivity is 0.085W / (m·K). According to the GBT17431-2010 standard, the cylinder compressive strength of ultra-light coarse aggregate with a density grade of 300 must be greater than 0.5MPa, so it meets the standard.

[0031] Example 3 This embodiment provides a method for producing ultralight hollow foam ceramic balls, and the specific steps are as follows: After drying the lithobite tailings, the mixture was weighed to have a dry weight percentage of 92.5% lithobite tailings, 0.5% silicon carbide, 1% bentonite, and 6% sodium carbonate and potassium carbonate (sodium carbonate:potassium carbonate molar ratio of 1:1). The mixture was dry-milled to obtain a mixture. The mixture was then dry-pressed at a pressure of 20 MPa to produce green balls. The green balls were dried at 120°C for 10 minutes, preheated at 700°C for 10 minutes, and then calcined at 1140°C for 30 minutes. After calcination, the mixture was allowed to cool naturally to obtain ultra-lightweight hollow foam ceramic balls.

[0032] After testing, the outer diameter of the ultra-light foam ceramic hollow ball is 15mm, the cavity diameter is 6.5mm, and the bulk density is 360kg / m 3 The 1h mass water absorption rate is 7.8%, the cylinder compressive strength is 1.2MPa, and the thermal conductivity is 0.091W / (m·K). According to the GBT17431-2010 standard, the cylinder compressive strength of ultra-light coarse aggregate with a density grade of 400 must be greater than 1.0MPa, so it meets the standard.

[0033] Example 4 This embodiment provides a method for producing ultralight hollow foam ceramic balls, and the specific steps are as follows: After drying the lithobite tailings, the mixture was weighed to have a dry weight percentage of 92.5% lithobite tailings, 0.5% silicon carbide, 1% bentonite, and 6% sodium carbonate and potassium carbonate (sodium carbonate:potassium carbonate molar ratio of 1:1). The mixture was dry-milled to obtain a mixture. The mixture was then dry-pressed at a pressure of 10 MPa to produce green balls. The green balls were dried at 120°C for 10 minutes, preheated at 700°C for 10 minutes, and then calcined at 1120°C for 30 minutes. After calcination, the mixture was allowed to cool naturally to obtain ultra-lightweight hollow foam ceramic balls.

[0034] After testing, the outer diameter of the ultra-light foam ceramic hollow ball is 15mm, the cavity diameter is 7.8mm, and the bulk density is 260kg / m 3 The 1h mass water absorption rate is 2.3%, the cylinder compressive strength is 1.36MPa, and the thermal conductivity is 0.086W / (m·K). According to the GBT17431-2010 standard, the cylinder compressive strength of ultra-light coarse aggregate with a density grade of 300 must be greater than 0.5MPa, so it meets the standard.

[0035] Comparative Example 1 After drying the lithobite tailings, the mixture was weighed to have a dry weight percentage of 92.5% lithobite tailings, 0.5% silicon carbide, 1% bentonite, and 6% sodium carbonate and potassium carbonate (sodium carbonate:potassium carbonate molar ratio of 1:1). The mixture was dry-milled to obtain a green ball. The green ball was then dry-pressed at a pressure of 1 MPa to produce green balls. The green balls were dried at 120°C for 10 minutes, preheated at 700°C for 10 minutes, and then calcined at 1140°C for 30 minutes. After calcination, the mixture was allowed to cool naturally to obtain foam ceramic solid balls.

[0036] After testing, the bulk density of foam ceramic solid balls is 520kg / m 3 The 1-hour mass water absorption rate is 1.9%, the cylinder compressive strength is 1.8 MPa, and the thermal conductivity is 0.18 W / (m·K). According to the GBT17431-2010 standard, the cylinder compressive strength of ultra-light coarse aggregate with a density grade of 600 must be greater than 2.0 MPa, so it does not meet the standard.

[0037] From the results of Comparative Example 1, it can be seen that when the molding pressure is relatively low, the density of the green ball body is too low, which does not match the high-temperature foaming environment, resulting in the acquisition of foamed ceramic solid balls.

[0038] Comparative Example 2 After drying the lithobite tailings, the mixture was weighed to have a dry weight percentage of 92.5% lithobite tailings, 0.5% silicon carbide, 1% bentonite, and 6% sodium carbonate and potassium carbonate (sodium carbonate:potassium carbonate molar ratio of 1:1). The mixture was dry-milled to obtain a green ball. The green ball was then dry-pressed at a pressure of 30 MPa to obtain green balls. The green balls were dried at 120°C for 10 minutes, preheated at 700°C for 10 minutes, and then calcined at 1140°C for 30 minutes. After calcination, the mixture was allowed to cool naturally to obtain foam ceramic solid balls.

[0039] After testing, the bulk density of foam ceramic solid balls is 410kg / m 3 The 1-hour mass water absorption rate is 11.9%, the cylinder compressive strength is 1.25 MPa, and the thermal conductivity is 0.12 W / (m·K). According to the GBT17431-2010 standard, the cylinder compressive strength of ultra-light coarse aggregate with a density grade of 500 must be greater than 1.5 MPa, so it does not meet the standard.

[0040] From the results of Comparative Example 2, it can be seen that when the molding pressure is too high, the density of the green balls is too high, which is not conducive to high-temperature foaming and expansion, thereby forming foam ceramic solid balls.

[0041] Comparative Example 3 This comparative example is the same as the technical solution provided in Example 1, with the only difference being that: The silicon carbide in the raw material components was replaced with an equal mass of silicon nitride. The other steps and parameters were the same as in Example 1. The finished product obtained in this case was a foam ceramic solid ball. The bulk density of the foam ceramic solid ball was 820 kg / m 3 , 1h mass water absorption rate is 3%, cylinder pressure strength is 3.25MPa. According to GBT17431-2010 standard, the bulk density of ultra-light coarse aggregate with density grade 500 is not more than 500kg / m 3 , so it does not meet the standards.

[0042] The results in Comparative Example 3 show that solid foam ceramic spheres formed when silicon nitride was used as the foaming agent. This is because the oxidation rate and foaming temperature of silicon nitride are not compatible with the skeleton structure of the ferroleum mica tailings and bentonite, resulting in hollow foam ceramic spheres after the same treatment. The present inventors also attempted to explore suitable processing conditions for silicon nitride, such as molding pressure and calcination temperature, through experimental optimization, but were unable to obtain suitable ultralight hollow foam ceramic spheres.

[0043] Comparative Example 4 This comparative example is the same as the technical solution provided in Example 1, with the only difference being that: The bentonite in the raw material components was replaced with kaolin of equal mass. The other steps and parameters were the same as those in Example 1. The finished product obtained in this case was a foam ceramic solid ball. The bulk density of the foam ceramic solid ball was 560 kg / m 3 , 1h mass water absorption rate is 2.5%, cylinder pressure strength is 1.25MPa. According to GBT17431-2010 standard, the bulk density of ultra-light coarse aggregate with density grade 500 is not more than 500kg / m 3 , so it does not meet the standards.

[0044] From the results in Comparative Example 4, it can be seen that when kaolin is used as a binder, foam ceramic solid balls are formed. The reason is that: the viscosity of kaolin is weaker than that of bentonite, resulting in a lower strength of the raw ball skeleton structure, which leads to a mismatch between the raw ball density and the high-temperature foaming of the foaming agent, resulting in the formation of foam ceramic solid balls when kaolin is used as a binder. Therefore, bentonite is more suitable for forming foam ceramic hollow balls as a binder. The present invention also attempts to explore processing conditions such as molding pressure and roasting temperature suitable for silicon nitride through experimental optimization, but the result is also unable to obtain suitable ultra-light foam ceramic hollow balls.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A hollow foam ceramic ball, characterized in that: The raw materials of the hollow foam ceramic spheres include: iron lithium mica tailings, silicon carbide, bentonite, sodium carbonate and potassium carbonate; In percentage by mass, the content of the iron lithium mica tailings is 90 to 96.4%; the content of silicon carbide is 0.1 to 1%; In terms of mass percentage, the SiO2 in the iron lithium mica tailings is 77-80%, Al2O3 is 10-13%, Fe2O3 is 1.3-1.6%, and Li2O is 0.1-0.17%.

2. The hollow ceramic foam ball according to claim 1, characterized in that: In terms of mass percentage, the iron lithium mica tailings contain 77-80% SiO2, 10-13% Al2O3, 3.2-3.6% K2O, 1.3-1.6% Fe2O3, 0.1-0.2% MgO, 0.5-0.7% Na2O, 0.1-0.17% Li2O, and a loss on ignition of 1.9-2.2%.

3. The hollow ceramic foam ball according to claim 1 or 2, characterized in that: The silicon carbide has a particle size of less than 20 μm and a purity of greater than 85%; preferably, the silicon carbide is black silicon carbide micropowder and / or green silicon carbide micropowder.

4. The hollow ceramic foam sphere according to any one of claims 1 to 3, characterized in that: In terms of mass percentage, the bentonite is 0.5-1%, and the total of the sodium carbonate and potassium carbonate is 3-8%.

5. The hollow ceramic foam ball according to claim 4, characterized in that: The montmorillonite content in the bentonite is 55-80%, and the particle size is less than 45 μm; preferably, the bentonite is sodium-based bentonite and / or calcium-based bentonite.

6. The hollow ceramic foam sphere according to claim 4 or 5, characterized in that: In terms of molar ratio, the ratio of sodium carbonate to potassium carbonate is (1-3): (1-3).

7. The method for preparing the hollow foam ceramic spheres according to any one of claims 1 to 6, characterized in that: include: The iron lithium mica tailings, silicon carbide, bentonite, sodium carbonate and potassium carbonate are mixed and finely ground to obtain a mixture; Pressing the mixture into shapes to obtain green balls; The green balls are sequentially dried, preheated, calcined and cooled to obtain foamed ceramic hollow balls.

8. The preparation method according to claim 7, characterized in that The pressure of the compression molding is 5~20MPa.

9. The preparation method according to claim 7 or 8, characterized in that The drying conditions include: drying temperature of 100-200° C., drying time of 5-10 minutes; and / or, The preheating conditions include: preheating temperature of 400-700°C, preheating time of 10-30 minutes; and / or, The calcination conditions include: a calcination temperature of 1100-1200° C. and a calcination time of 10-60 minutes.

10. Use of the hollow ceramic foam sphere according to any one of claims 1 to 6 in any of the following applications: (1) Preparation of ultra-light aggregate; (2) Preparation of refractory materials; (3) Preparation of noise reduction materials; (4) Preparation of filtering or separation materials; (5) Preparation of catalyst supports or reactor materials; (6) Preparation of environmental remediation materials; (7) Preparation of electromagnetic functional materials.

Images