Method for preparing sintered hollow batten from high-content graphite tailings

Abstract

The invention discloses a method for preparing a sintered hollow batten from high-doping-amount graphite tailings, pretreated graphite tailings are used as a main raw material, coal gangue and functional auxiliaries are matched, the use amount of the graphite tailings is 40%-65%, the use amount of the coal gangue is 30%-50%, and the functional auxiliaries comprise mullite powder, rice hull ash and a polycarboxylic acid drag reducer. The preparation method comprises the following steps: burdening raw materials, adding water, mixing, aging, carrying out vacuum extrusion molding to obtain a green body, and sintering by a segmented drying and programmed roasting process to obtain a finished product. By optimizing the raw material ratio and process parameters, the problems of poor plasticity and difficult forming of high-doping-amount graphite tailings are solved, the prepared sintered hollow batten has the advantages of light weight, high strength and low water absorption rate, the compressive strength exceeds 10 MPa, the dry density is lower than 800 kg / m < 3 >, all performance indexes meet the standard requirements of light partition battens for buildings, and the sintered hollow batten is suitable for large-scale popularization and application. And an effective technical approach is provided for large-scale high-value utilization of the graphite tailings.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wall material preparation, and particularly relates to a method for preparing sintered hollow strip boards by using high-content graphite tailings. BACKGROUND

[0002] With the continuous advancement of urbanization process and the rapid development of building industrialization in China, the requirements for wall materials are increasingly improved. As an important building wall material, sintered hollow strip boards have been widely used in the field of building partition walls due to their good fireproof performance, sound insulation effect, durability and thermal performance. However, the production of traditional sintered hollow strip boards mainly relies on high-quality clay or shale as the main raw material, which not only consumes a large amount of valuable land resources, causes damage to arable land and deterioration of the ecological environment, but also is increasingly restricted by national industrial policies and environmental protection regulations. According to incomplete statistics, about 10 cubic meters of land resources are consumed for producing 10,000 pieces of clay bricks, and this unsustainable production mode needs to be changed urgently.

[0003] Under such a background, it has become an inevitable choice for the sustainable development of the building material industry to find and large-scale use of clay substitute resources and develop new environmentally friendly wall materials. At the same time, a large amount of graphite tailings are produced in the graphite ore dressing industry in China every year, and these tailings are usually discharged to the tailings pond in the form of slurry. Data shows that about 10-15 tons of tailings are produced for every ton of graphite concentrate, and the amount of graphite tailings produced in China every year is huge. The storage of these tailings not only occupies a large amount of land resources, but also has the safety hazard of tailings dam collapse, and the fine particle tailings flying in the air continuously pollute the surrounding air, soil and water, and the ecological environmental pressure is increasingly prominent.

[0004] At present, some studies have attempted to use graphite tailings to prepare sintered building materials in order to realize the resource utilization of solid waste. However, these technologies face many technical problems in the process of actual popularization and application. First, graphite tailings are a kind of infertile material, and their particle morphology and physical properties are significantly different from clay, and their plasticity and binding property are poor. When the content exceeds 30%, the plasticity index of the mixture decreases significantly, which leads to problems such as insufficient green body strength, cracking, and difficulty in forming a complete pore structure during extrusion molding. Even if it is forced to form, the green body is also prone to bending, deformation or even breaking during subsequent drying and calcination due to uneven shrinkage, which seriously affects the dimensional regularity of the product and the qualified rate of the finished product.

[0005] Secondly, in terms of sintering process, the chemical composition of graphite tailings is mainly SiO2, which belongs to high-silicon raw materials, and the sintering temperature range is narrow, and the sintering activity is poor. In order to achieve good sintering densification, a higher calcination temperature is needed, which not only increases the energy consumption, but also easily leads to overfiring or underfiring of the product due to improper temperature control. Overfiring will cause the product to deform and vitrify excessively; underfiring will lead to insufficient strength and poor durability of the product. In addition, under the condition of high dosage, trace amounts of residual flotation reagents that may be contained in the tailings volatilize at high temperatures, easily forming too many pores or black cores in the body, affecting the appearance quality and internal structure uniformity of the product.

[0006] More importantly, the existing technology mostly stays at the level of simple replacement of clay, and lacks the support of systematic material science theory. Traditional formula design often ignores the matching of the physical and chemical changes of various raw materials during heat treatment, especially lacks in-depth research on key technical problems such as how to promote low-temperature liquid phase generation, optimize pore structure, and enhance the bending strength of the body by introducing specific functional additives. In addition, the existing process has not effectively solved the problem of the collaborative utilization of high-dosage graphite tailings and coal gangue and other solid wastes, resulting in the product performance being difficult to meet the specification requirements of the building lightweight partition strip board.

[0007] Therefore, in view of the problems of large raw material consumption, low tailings utilization rate, difficulty in forming, narrow sintering temperature window, and unstable product performance in the existing technology, it is urgent to develop a new process method. The present application proposes a method for preparing sintered hollow strip board from high-dosage graphite tailings by systematically studying the internal relationship between raw material ratio, functional additives, forming process and sintering system. This method not only realizes the bulk and high-value utilization of graphite tailings, but also effectively solves many problems in the existing technology, and provides strong technical support for promoting the green and sustainable development of the building materials industry. SUMMARY

[0008] The purpose of the present application is to provide a method for preparing sintered hollow strip board from high-dosage graphite tailings, to solve the problems of poor plasticity of the mixture, difficulty in extrusion forming, and easy cracking and deformation of the body caused by high-dosage (40%-65%) graphite tailings as a barren material; to optimize the sintering process, broaden the sintering temperature window, and avoid high-temperature overfiring or low-temperature underfiring caused by the high-silicon characteristics of graphite tailings, to ensure the strength and stability of the product; to realize the efficient collaborative utilization of graphite tailings and coal gangue and other solid wastes, to produce lightweight, high-strength sintered hollow strip board with performance meeting the building standard requirements, and to realize the bulk and high-value utilization of solid wastes.

[0009] The purpose of the present application is achieved by the following technical solutions: A method for preparing sintered hollow strip board from high-dosage graphite tailings, comprising the following steps: (1) Raw material ratio: Prepare the following parts by weight of raw materials: Graphite tailings: 40-65 parts, which are pre-dried and crushed to a particle size ≤0.1mm; Coal gangue: 30-50 parts, which is subjected to two-stage crushing by jaw crusher and hammer crusher; Functional additives: 4.5~10 parts; the functional additives are composed of the following components: 3~5 parts of mullite powder with a particle size range of 0.02~0.05mm and the proportion of this particle size ≥30%, 1~3 parts of rice husk ash, and 0.5~2 parts of polycarboxylate drag reducer; (2) Mixing and aging: The above raw materials are mixed in a mixing device, water is added until the moisture content of the mixture is 17%~20%, and after being stirred evenly, it is aged at room temperature for 48~72 hours to obtain a plastic mixture; (3) Vacuum extrusion molding: The aged plastic mixture is fed into a two-stage vacuum extruder and extruded under the conditions of controlling the vacuum degree to be -0.02~-0.06MPa and the extrusion pressure to be 2.5~2.7MPa. The green body is obtained by online cutting. (4) Segmented drying: The green billet is first placed in a windless environment at room temperature for 10 to 12 hours for pre-drying; then it is transferred to a forced-air drying oven and dried at 105°C to constant weight to obtain the dry billet; (5) Programmatic calcination: The dry blank is placed in a programmable temperature controlled muffle furnace for calcination, and the following heating regime is followed: the temperature is increased from room temperature to 300℃ at a rate of 3~5℃ / min and held for 0.5~1h; then the temperature is increased to 800℃ at a rate of 2~4℃ / min and held for 1~2h; finally the temperature is increased to 950~1050℃ at a rate of 1~2℃ / min and held for 4~6h; after calcination, the blank is cooled with the furnace to obtain the sintered hollow strip plate.

[0010] Preferably, in step (1), the drying temperature of the graphite tailings is 180~200℃. This temperature can effectively remove moisture without damaging the tailings structure.

[0011] Preferably, in step (2), the mixing equipment used is either a twin-shaft vacuum mixer or a vacuum plywood machine. Using a twin-shaft vacuum mixer or a vacuum plywood machine ensures uniform mixing and initially removes some air.

[0012] Preferably, in step (3), a die core frame for forming internal holes in the strip is provided at the extruder nozzle, and the die core frame is chrome-plated to improve wear resistance and ensure the quality of hole forming and die life.

[0013] Preferably, in step (5), during the 300℃ heat preservation stage, a stepped heating method is adopted, specifically: first, the temperature is raised to 150℃ and kept for 20-30 minutes, and then the temperature is raised to 300℃ for heat preservation. This method is conducive to the gradual discharge of residual moisture and organic matter, and reduces internal defects of the green body.

[0014] Preferably, in step (1), 1 to 3 parts of sintering aid are added to the raw materials, wherein the sintering aid is at least one of waste glass powder or feldspar powder crushed to less than 0.1 mm.

[0015] Preferably, in step (1), the coal gangue is non-self-igniting gangue with a fixed carbon content controlled at 5% to 15%. It serves as both a plastic component and can provide some internal fuel during roasting, thus optimizing the thermal regime.

[0016] Preferably, in step (1), 1 to 3 parts of sintering aid may be added to the raw materials. The sintering aid is at least one of waste glass powder or feldspar powder crushed to less than 0.1 mm, so as to further promote low-temperature sintering and reduce energy consumption.

[0017] Preferably, the porosity of the sintered hollow strip is 30%~40%, and the dry density is ≤800kg / m³. 3 Lightweight class.

[0018] This application also claims protection for a sintered hollow bar plate prepared by the above-mentioned method for preparing sintered hollow bars plate with high graphite tailings content.

[0019] Preferably, its compressive strength is not less than 5 MPa and its flexural strength is not less than 2 MPa.

[0020] Due to the application of the above technical solution, the present invention has the following beneficial effects compared with the prior art: 1. This invention utilizes high-volume waste utilization, resulting in significant environmental benefits. For the first time, the content of graphite tailings is increased to a high level of 40%~65%, and coal gangue is used in conjunction, realizing the co-processing and high-value utilization of two major solid wastes, significantly reducing environmental burden and production costs. 2. The formulation of this invention is scientific and synergistic. It innovatively introduces a functional additive system composed of mullite powder, rice husk ash, and polycarboxylate drag reducer. Mullite powder effectively fills pores and acts as aggregate to enhance flexural strength. Rice husk ash is rich in amorphous SiO2, which can effectively promote the formation of low-temperature liquid phase, reduce sintering temperature, and reduce high-temperature shrinkage. The polycarboxylate drag reducer significantly improves the rheological properties of high-content tailings mixture, ensuring high efficiency in extrusion molding and uniformity of green body quality, thus solving the core pain point of difficult molding of lean materials. 3. The process of this invention is optimized, resulting in excellent product performance. Through the refined control of the entire process of "aging-vacuum extrusion-segmented drying-programmed calcination", aging stimulates ion exchange in the raw materials and enhances plasticity; vacuum extrusion ensures that the green body is dense and defect-free; segmented drying avoids cracking; and the programmed calcination process precisely controls key processes such as organic matter decomposition, carbonate decomposition, and quartz crystal transformation, ultimately obtaining sintered hollow strip products with uniform structure, regular pores, and high strength. 4. This invention is easy to promote and has broad application prospects: The raw materials of this invention are widely available and inexpensive, and the process route is clear. It is easy to modify and promote on existing sintering product production lines, providing a brand-new green product solution for the building materials industry, with broad market prospects. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, some of the drawings in the following description are some embodiments of the present invention. For those skilled in the art, other drawings can be made based on these drawings without creative effort.

[0022] Figure 1 This is a sample image of the sintered hollow strip plate prepared in Example 1 of the present invention. Detailed Implementation

[0023] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific implementation schemes are now described in detail.

[0024] The present invention will be further described below with reference to embodiments, but the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0025] Example 1 See appendix Figure 1 This embodiment provides a method for preparing sintered hollow strips from high-content graphite tailings, comprising the following steps: (1) Raw material ratio: Prepare the following raw materials in parts by weight: 60 parts graphite tailings, 34 parts coal gangue, 3 parts mullite powder, 2.5 parts rice husk ash, and 0.5 parts polycarboxylate drag reducer; wherein the graphite tailings are pre-dried at 190℃ and crushed to a particle size ≤0.1mm; the coal gangue is subjected to two-stage crushing by jaw crusher and hammer crusher, and the fixed carbon content is controlled at 8%; the particle size range of mullite powder is 0.02~0.05mm and the proportion of this particle size is ≥30%; (2) Mixing and aging: The above raw materials are mixed in a twin-shaft vacuum mixer, water is added until the moisture content of the mixture is 18%, and after being stirred evenly, it is aged at room temperature for 48 hours to obtain a plastic mixture; (3) Vacuum extrusion molding: The aged plastic mixture is put into a two-stage vacuum extruder and extruded under the conditions of controlling the vacuum degree to -0.05MPa and the extrusion pressure to 2.6MPa. The die core frame with chrome plating is provided at the extruder nozzle to form internal holes, and the green body with a size of 3000mm×600mm×100mm is obtained by online cutting. (4) Segmented drying: The green billet is first placed in a windless environment at room temperature for 12 hours for pre-drying; then it is transferred to a forced-air drying oven and dried at 105°C to constant weight to obtain the dry billet; (5) Programmatic calcination: The dry blank is placed in a programmable temperature controlled muffle furnace for calcination, and the following heating regime is followed: the temperature is increased from room temperature to 300℃ at a rate of 4℃ / min and held for 1h; then the temperature is increased to 800℃ at a rate of 3℃ / min and held for 1.5h; finally the temperature is increased to 1000℃ at a rate of 1.5℃ / min and held for 4h; after calcination, the blank is cooled with the furnace to obtain the sintered hollow strip plate.

[0026] Example 2 This embodiment provides a method for preparing sintered hollow strips from high-content graphite tailings, including the following steps: (1) Raw material ratio: Prepare the following raw materials in parts by weight: 65 parts graphite tailings, 30 parts coal gangue, 3 parts mullite powder, 1.5 parts rice husk ash, and 0.5 parts polycarboxylate drag reducer; wherein the graphite tailings are pre-dried at 180℃ and crushed to a particle size ≤0.1mm; the coal gangue is subjected to two-stage crushing by jaw crusher and hammer crusher, and the fixed carbon content is controlled at 6%; the particle size range of mullite powder is 0.02~0.05mm and the proportion of this particle size is ≥30%; (2) Mixing and aging: The above raw materials are mixed in a vacuum ply mill, water is added until the moisture content of the mixture is 18%, and after stirring evenly, it is aged at room temperature for 60 hours to obtain a plastic mixture; (3) Vacuum extrusion molding: The aged plastic mixture is put into a two-stage vacuum extruder and extruded under the conditions of controlling the vacuum degree to -0.04MPa and the extrusion pressure to 2.5MPa. The die core frame with chrome plating is provided at the extruder nozzle to form internal holes, and the green body with a size of 3000mm×600mm×100mm is obtained by online cutting. (4) Segmented drying: The green billet is first placed in a windless environment at room temperature for 10 hours for pre-drying; then it is transferred to a forced-air drying oven and dried at 105°C to constant weight to obtain the dry billet; (5) Programmatic calcination: The dry blank is placed in a programmable temperature controlled muffle furnace for calcination, and the following heating regime is followed: the temperature is increased from room temperature to 300℃ at a rate of 3℃ / min and held for 0.5h; then the temperature is increased to 800℃ at a rate of 2℃ / min and held for 2h; finally the temperature is increased to 1000℃ at a rate of 1℃ / min and held for 4h; after calcination, the blank is cooled with the furnace to obtain the sintered hollow strip plate.

[0027] Example 3 This embodiment provides a method for preparing sintered hollow strips from high-content graphite tailings, including the following steps: (1) Raw material ratio: Prepare the following raw materials in parts by weight: 50 parts graphite tailings, 45 parts coal gangue, 3 parts mullite powder, 1.5 parts rice husk ash, and 0.5 parts polycarboxylate drag reducer; wherein the graphite tailings are pre-dried at 200℃ and crushed to a particle size ≤0.1mm; the coal gangue is subjected to two-stage crushing by jaw crusher and hammer crusher, and the fixed carbon content is controlled at 10%; the particle size range of mullite powder is 0.02~0.05mm and the proportion of this particle size is ≥30%; (2) Mixing and aging: The above raw materials are mixed in a twin-shaft vacuum mixer, water is added until the moisture content of the mixture is 17%, and after stirring evenly, it is aged at room temperature for 48 hours to obtain a plastic mixture; (3) Vacuum extrusion molding: The aged plastic mixture is put into a two-stage vacuum extruder and extruded under the conditions of controlling the vacuum degree to -0.06MPa and the extrusion pressure to 2.7MPa. The die core frame with chrome plating is provided at the extruder nozzle to form internal holes, and the green body with a size of 3000mm×600mm×100mm is obtained by online cutting. (4) Segmented drying: The green billet is first placed in a windless environment at room temperature for 11 hours for pre-drying; then it is transferred to a forced-air drying oven and dried at 105°C to constant weight to obtain the dry billet; (5) Programmatic calcination: The dry blank is placed in a programmable temperature controlled muffle furnace for calcination, and the following heating regime is followed: the temperature is increased from room temperature to 300°C at a rate of 5°C / min and held for 0.5h; then the temperature is increased to 800°C at a rate of 4°C / min and held for 1h; finally the temperature is increased to 950°C at a rate of 2°C / min and held for 4h; after calcination, the blank is cooled with the furnace to obtain the sintered hollow strip plate.

[0028] Example 4 This embodiment provides a method for preparing sintered hollow strips from high-content graphite tailings, including the following steps: (1) Raw material ratio: Prepare the following raw materials in parts by weight: 40 parts graphite tailings, 50 parts coal gangue, 5 parts mullite powder, 3 parts rice husk ash, and 2 parts polycarboxylate drag reducer; wherein the graphite tailings are pre-dried at 190℃ and crushed to a particle size ≤0.1mm; the coal gangue is subjected to two-stage crushing by jaw crusher and hammer crusher, and the fixed carbon content is controlled at 12%; the particle size range of mullite powder is 0.02~0.05mm and the proportion of this particle size is ≥30%; (2) Mixing and aging: The above raw materials are mixed in a twin-shaft vacuum mixer, water is added until the moisture content of the mixture is 17%, and after being stirred evenly, it is aged at room temperature for 72 hours to obtain a plastic mixture; (3) Vacuum extrusion molding: The aged plastic mixture is put into a two-stage vacuum extruder and extruded under the conditions of controlling the vacuum degree to -0.05MPa and the extrusion pressure to 2.6MPa. The die core frame with chrome plating is provided at the extruder nozzle to form internal holes, and the green body with a size of 3000mm×600mm×100mm is obtained by online cutting. (4) Segmented drying: The green billet is first placed in a windless environment at room temperature for 12 hours for pre-drying; then it is transferred to a forced-air drying oven and dried at 105°C to constant weight to obtain the dry billet; (5) Programmatic calcination: The dry blank is placed in a programmable temperature controlled muffle furnace for calcination according to the following heating regime: the temperature is increased from room temperature to 300℃ at a rate of 3℃ / min and held for 1h; then the temperature is increased to 800℃ at a rate of 2℃ / min and held for 2h; finally the temperature is increased to 950℃ at a rate of 1℃ / min and held for 6h; after calcination, the blank is cooled with the furnace to obtain the sintered hollow strip plate.

[0029] Example 5 This embodiment provides a method for preparing sintered hollow strips from high-content graphite tailings, including the following steps: (1) Raw material ratio: Prepare the following raw materials in parts by weight: 45 parts graphite tailings, 50 parts coal gangue, 3 parts mullite powder, 1.5 parts rice husk ash, 0.5 parts polycarboxylate drag reducer, and 2 parts waste glass powder; wherein the graphite tailings are pre-dried at 190℃ and crushed to a particle size ≤0.1mm; the coal gangue is crushed in two stages by jaw crusher and hammer crusher, and the fixed carbon content is controlled at 9%; the particle size range of mullite powder is 0.02~0.05mm and the proportion of this particle size is ≥30%; the waste glass powder is crushed to below 0.1mm; (2) Mixing and aging: The above raw materials are mixed in a twin-shaft vacuum mixer, water is added until the moisture content of the mixture is 18%, and after being stirred evenly, it is aged at room temperature for 48 hours to obtain a plastic mixture; (3) Vacuum extrusion molding: The aged plastic mixture is put into a two-stage vacuum extruder and extruded under the conditions of controlling the vacuum degree to -0.05MPa and the extrusion pressure to 2.6MPa. The die core frame with chrome plating is provided at the extruder nozzle to form internal holes, and the green body with a size of 3000mm×600mm×100mm is obtained by online cutting. (4) Segmented drying: The green billet is first placed in a windless environment at room temperature for 12 hours for pre-drying; then it is transferred to a forced-air drying oven and dried at 105°C to constant weight to obtain the dry billet; (5) Programmatic calcination: The dry blank is placed in a programmable temperature controlled muffle furnace for calcination, and the following heating regime is followed: the temperature is increased from room temperature to 300℃ at a rate of 4℃ / min and held for 1h; then the temperature is increased to 800℃ at a rate of 3℃ / min and held for 1.5h; finally the temperature is increased to 1000℃ at a rate of 1.5℃ / min and held for 4h; after calcination, the blank is cooled with the furnace to obtain the sintered hollow strip plate.

[0030] Example 6 This embodiment provides a method for preparing sintered hollow strips from high-content graphite tailings, including the following steps: (1) Raw material ratio: Prepare the following raw materials in parts by weight: 50 parts graphite tailings, 40 parts coal gangue, 5 parts mullite powder, 3 parts rice husk ash, and 2 parts polycarboxylate drag reducer; wherein the graphite tailings are pre-dried at 190℃ and crushed to a particle size ≤0.1mm; the coal gangue is subjected to two-stage crushing by jaw crusher and hammer crusher, and the fixed carbon content is controlled at 11%; the particle size range of mullite powder is 0.02~0.05mm and the proportion of this particle size is ≥30%; (2) Mixing and aging: The above raw materials are mixed in a twin-shaft vacuum mixer, water is added until the moisture content of the mixture is 17%, and after stirring evenly, it is aged at room temperature for 48 hours to obtain a plastic mixture; (3) Vacuum extrusion molding: The aged plastic mixture is put into a two-stage vacuum extruder and extruded under the conditions of controlling the vacuum degree to -0.05MPa and the extrusion pressure to 2.6MPa. The die core frame with chrome plating is provided at the extruder nozzle to form internal holes, and the green body with a size of 3000mm×600mm×100mm is obtained by online cutting. (4) Segmented drying: The green billet is first placed in a windless environment at room temperature for 12 hours for pre-drying; then it is transferred to a forced-air drying oven and dried at 105°C to constant weight to obtain the dry billet; (5) Programmatic calcination: The dry blank is placed in a programmable temperature controlled muffle furnace for calcination, and the following heating regime is followed: the temperature is increased from room temperature to 150°C at a rate of 4°C / min and held for 25 minutes; then the temperature is increased to 300°C and held for 1 hour; then the temperature is increased to 800°C at a rate of 3°C / min and held for 1.5 hours; finally the temperature is increased to 1050°C at a rate of 1.5°C / min and held for 4 hours; after calcination, the blank is cooled with the furnace to obtain the sintered hollow strip plate.

[0031] Comparative Example 1 This comparative example provides a method for sintering hollow strips, including the following steps: (1) Raw material ratio: Prepare the following raw materials by weight: 94 parts coal gangue, 3 parts mullite powder, 2.5 parts rice husk ash, and 0.5 parts polycarboxylate drag reducer; the coal gangue is subjected to two-stage crushing by jaw crusher and hammer crusher, and the fixed carbon content is controlled at 8%; (2) Mixing and aging: The above raw materials are mixed in a twin-shaft vacuum mixer, water is added until the moisture content of the mixture is 18%, and after being stirred evenly, it is aged at room temperature for 48 hours to obtain a plastic mixture; (3) Vacuum extrusion molding: The aged plastic mixture is put into a two-stage vacuum extruder and extruded under the conditions of controlling the vacuum degree to -0.05MPa and the extrusion pressure to 2.6MPa. The die core frame with chrome plating is provided at the extruder nozzle to form internal holes, and the green body with a size of 3000mm×600mm×100mm is obtained by online cutting. (4) Segmented drying: The green billet is first placed in a windless environment at room temperature for 12 hours for pre-drying; then it is transferred to a forced-air drying oven and dried at 105°C to constant weight to obtain the dry billet; (5) Programmatic calcination: The dry blanks were placed in a programmable temperature controlled muffle furnace for calcination, and the following heating regime was followed: the temperature was increased from room temperature to 300℃ at a rate of 4℃ / min and held for 1h; then the temperature was increased to 800℃ at a rate of 3℃ / min and held for 1.5h; finally the temperature was increased to 1000℃ at a rate of 1.5℃ / min and held for 4h; after calcination, the blanks were cooled with the furnace to obtain the comparison strips.

[0032] Comparative Example 2 This comparative example provides a method for sintering hollow strips, including the following steps: (1) Raw material ratio: Prepare the following raw materials by weight: 94 parts graphite tailings, 3 parts mullite powder, 2.5 parts rice husk ash, 0.5 parts polycarboxylate drag reducer; the graphite tailings are dried at 190℃ and crushed to a particle size ≤0.1mm. (2) Mixing and aging: The above raw materials are mixed in a twin-shaft vacuum mixer, water is added until the moisture content of the mixture is 18%, and after being stirred evenly, it is aged at room temperature for 48 hours to obtain the mixture; (3) Vacuum extrusion molding: The aged mixture is put into a two-stage vacuum extruder and extruded under the conditions of controlling the vacuum degree to -0.05MPa and the extrusion pressure to 2.6MPa. The die core frame with chrome plating is provided at the extruder nozzle to form internal holes, and the green body is obtained by online cutting. (4) Segmented drying: The green billet is first placed in a windless environment at room temperature for 12 hours for pre-drying; then it is transferred to a forced-air drying oven and dried at 105°C to constant weight to obtain the dry billet; (5) Programmatic calcination: The dry blanks were placed in a programmable temperature controlled muffle furnace for calcination, and the following heating regime was followed: the temperature was increased from room temperature to 300℃ at a rate of 4℃ / min and held for 1h; then the temperature was increased to 800℃ at a rate of 3℃ / min and held for 1.5h; finally the temperature was increased to 1000℃ at a rate of 1.5℃ / min and held for 4h; after calcination, the blanks were cooled with the furnace to obtain the comparison strips.

[0033] The strips prepared in the above embodiments and comparative examples were tested, and the test results are shown in Table 1.

[0034] Table 1

[0035] As shown in Table 1, the formulation exhibits a significant synergistic effect. Examples 1 to 6, through the rational proportioning of graphite tailings (40-65 parts) and coal gangue (30-50 parts), formed a good synergistic system for plastic molding and high-temperature sintering. The compressive strength (10.95-14.59 MPa) of all examples far exceeds the standard requirement (≥5.0 MPa), and the flexural strength (3.2-4.5 MPa) is also significantly higher than the standard (≥2.0 MPa), proving that this formulation system can effectively guarantee the mechanical properties of the material.

[0036] In Examples 4-6, the synergistic effect of mullite powder (3-5 parts) and rice husk ash (1.5-3 parts) achieved low-temperature sintering while ensuring material strength. Example 5, by adding 2 parts of waste glass powder as a sintering aid, obtained the highest compressive strength (14.59 MPa) and excellent flexural strength (4.5 MPa), demonstrating that functional additives have a significant effect on improving material properties.

[0037] Example 6 employs a stepped heating process, adding a 150℃ holding stage before reaching 300℃. Although the compressive strength (12.67MPa) is slightly lower than other examples, it is still far above the standard requirements, and the product exhibits better structural stability. The dry density of all examples is (745~785kg / m³).3 All meet the lightweight grade requirements (≤800kg / m³). 3 The porosity remains stable within the ideal range of 35-38%.

[0038] Comparative Example 1 (without graphite tailings) could be formed, but its dry density exceeded the standard (810 kg / m³). 3 The high water absorption rate (22.32%) and defective impact resistance of the sample demonstrate that using only coal gangue cannot achieve the lightweight and high-strength effect of this invention. Comparative Example 2 (without coal gangue) suffers from a lack of plastic components, making extrusion molding difficult and resulting in extremely low product strength (compressive strength 4.29 MPa), fully demonstrating the indispensability of the synergistic ratio of graphite tailings and coal gangue in this invention.

[0039] All performance tests conducted on the panels prepared in the above embodiments and comparative examples were performed in accordance with GB / T23451-2023 "Lightweight Partition Panels for Buildings", and the specific methods are as follows: (I) Compressive strength test: Equipment: Compression testing machine; Method: A 100mm×100mm×100mm cubic specimen was used and loaded at a rate of (1.0±0.1)kN / s until the specimen failed; Calculation: R = P / A, take the average value of 5 specimens.

[0040] (II) Flexural strength test: Equipment: Universal testing machine; Method: A 400mm×300mm×plate thickness specimen was used, and the three-point bending method was applied with a support point spacing of 300mm. Calculate: R = 3PL / 2bh 2 Take the average value of 3 specimens.

[0041] (III) Dry density test: Equipment: electronic balance, forced-air drying oven; Method: After the specimens were dried to constant weight, their mass and volume were measured. Calculation: ρ = m / V, take the average value of 3 specimens.

[0042] (IV) Porosity test: Equipment: electronic balance, water tank; Method: The saturated surface-dry mass and volume of the specimens were measured by immersion method; Calculation: P=[(m2-m1) / ρwaterV]×100%, take the average value of 3 specimens.

[0043] (V) 5-hour boiling water absorption rate test: Equipment: electric hot water bath, electronic balance; Method: The mass change of the specimen was measured after boiling for 5 hours; Calculation: W=[(m1-m0) / m0]×100%, take the average value of 3 specimens.

[0044] (VI) Impact resistance test: Equipment: 10kg sandbags, impact test frame; Method: Drop sandbags freely from a height of 1.5m to impact the board surface 5 times; Assessment: Observe whether cracks appear on the board surface.

[0045] All tests were conducted at a temperature of (23±2)℃ and a relative humidity of (50±5)%, with the specimens conditioned for 24 hours before testing.

[0046] In summary, this invention has successfully achieved the high-value utilization of high-content graphite tailings through optimized raw material ratios and process parameters. The sintered hollow strips prepared are lightweight, high-strength, and durable, and have significant industrial application value.

[0047] The embodiments described above merely illustrate more specific and detailed implementations of the present invention, and should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method of producing sintered hollow slabs from high volume graphite tailings, characterized by, The method comprises the following steps: (1) Raw material proportioning: the following raw materials are prepared: Graphite tailings: 40-65 parts, which are dried and crushed to a particle size of ≤0.1 mm in advance; Coal gangue: 30-50 parts, which is crushed by a jaw crusher and a hammer crusher for secondary crushing; Functional additives: 4.5-10 parts; the functional additives are composed of the following components: 3-5 parts of mullite powder with a particle size range of 0.02-0.05 mm and a particle size proportion of ≥30%, 1-3 parts of rice husk ash, and 0.5-2 parts of polycarboxylic acid drag reduction agent; (2) Mixing and aging: the above raw materials are mixed in a stirring device, water is added to the mixed material at a water content of 17%-20%, and after uniform stirring, the mixed material is aged at room temperature for 48-72 hours to obtain a plastic mixture; (3) Vacuum extrusion molding: the aged plastic mixture is put into a double-stage vacuum extruder, and is extruded and molded under the conditions of a controlled vacuum degree of -0.02 to -0.06 MPa and an extrusion pressure of 2.5-2.7 MPa, and is cut online to obtain a green body; (4) Sectional drying: the green body is first placed in a room-temperature windless environment for 10-12 hours for pre-drying, and then is transferred to a forced air drying oven for drying at 105°C until a constant weight is obtained to obtain a dry body; (5) Programmed sintering: the dry body is placed in a program-controlled muffle furnace for sintering, and is heated according to the following temperature rising schedule: from room temperature to 300°C at a rate of 3-5°C / min, holding for 0.5-1 h; then heated to 800°C at a rate of 2-4°C / min, holding for 1-2 h; finally heated to 950-1050°C at a rate of 1-2°C / min, holding for 4-6 h; after sintering, the furnace is cooled to obtain the sintered hollow strip plate.

2. A process for the preparation of sintered hollow slates from high volume graphite tailings according to claim 1, characterized in that, In step (1), the drying temperature of the graphite tailings is 180-200°C.

3. A method of producing sintered hollow slabs from high volume graphite tailings according to claim 1, characterized in that, In step (2), the stirring device used is one of a double-shaft vacuum stirrer and a vacuum pug mill.

4. The method of producing sintered hollow slabs from high volume graphite tailings according to claim 1, characterized in that, In step (3), a mold core rack forming the internal holes of the strip plate is arranged at the outlet of the extruder, and the mold core rack is subjected to surface chrome plating treatment.

5. The method of producing sintered hollow slabs from high volume graphite tailings according to claim 1, characterized in that, In step (5), during the holding at 300°C, the temperature is raised in steps, specifically: first raised to 150°C and held for 20-30 minutes, and then raised to 300°C for holding.

6. The method of producing sintered hollow slabs from high volume graphite tailings according to claim 1, characterized in that, In step (1), 1-3 parts of a sintering aid is further added to the raw materials, and the sintering aid is at least one of waste glass powder or feldspar powder crushed to below 0.1 mm.

7. A process for the preparation of sintered hollow slabs from high volume graphite tailings according to claim 1, characterized in that, In step (1), the coal gangue is gangue that has not been self-combusted, and the fixed carbon content is controlled to be 5%-15%.

8. A process for the preparation of sintered hollow slabs from high volume graphite tailings according to claim 1, characterized in that, The sintered hollow strip plate prepared has a porosity of 30% to 40% and a dry density grade of ≤800 kg / m 3 of a light weight level.

9. A sintered hollow strip, characterized in that The sintered hollow strip plate is prepared by the method of any one of claims 1-8.

10. The sintered hollow strip of claim 9, wherein The compressive strength is not less than 5 MPa, and the flexural strength is not less than 2 MPa.

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