Non-stick aluminum unburned ceramsite and its preparation method and application

Abstract

The present application relates to the technical field of new materials, and particularly discloses a non-stick aluminum unfired haydite, which is prepared from the following raw materials in parts by weight: steel slag powder 65-75 parts, high-alumina cement 3-8 parts, glass powder 20-30 parts, anti-stick aluminum agent 1.5-3 parts, and water 15-25 parts. The preparation method comprises the following steps: (1) uniformly mixing the steel slag, high-alumina cement, glass powder, anti-stick aluminum agent and water, and then granulating to obtain granular material; and (2) sequentially performing pre-curing and carbon mineralization curing on the granular material prepared in step (1) to obtain the non-stick aluminum unfired haydite. The carbon mineralization curing is performed by curing the pre-cured granular material in a gaseous atmosphere with a CO2 volume concentration of no less than 30%. The non-stick aluminum unfired haydite prepared by the present application has the advantages of light weight, high strength and low water absorption, and can be used as a substitute aggregate for refractory castable.

Description

Technical Field

[0001] This invention relates to the field of new materials technology, specifically to a non-stick aluminum non-fired ceramic aggregate, its preparation method, and its application. Background Technology

[0002] my country is a major producer of aluminum alloys. With the development of industries such as large aircraft, high-speed rail, and aerospace, the demand for high-end aluminum alloys is increasing year by year. In the production process of aluminum alloys, melting and casting is the first step in aluminum material production. This involves melting aluminum ingots at high temperatures in a smelting furnace and then directly casting them into aluminum rods. Moreover, during the melting and casting process, the molten aluminum alloy needs to be transported and distributed through troughs, distribution plates, etc. Smelting furnaces, troughs, and distribution plates are mainly made of refractory castables. These castables are mainly developed based on related products used in steel smelting and have the disadvantages of high bulk density, high thermal conductivity, and insufficient resistance to aluminum adhesion.

[0003] Energy conservation, environmental protection, high efficiency, green practices, and reduced production costs are trends in the development of smelting and casting technology. Rapid economic development is a double-edged sword. While the efficiency of economic development has greatly improved with the rapid growth of my country's aluminum industry, it has also placed pressure on environmental protection, safety, and energy conservation. With the continuous development of the green economy, the government has put forward higher requirements for environmental protection, energy conservation, and green practices. The smelting and casting workshop is the most prominent part of aluminum processing. The refractory castables used in the smelting furnace should improve insulation performance, increase thermal efficiency, fully utilize waste heat, reduce overall energy consumption, and lower production costs.

[0004] In fact, refractory castables used for aluminum casting do not need to possess very high temperature resistance. The temperature of molten aluminum alloys generally does not exceed 700℃. Therefore, substances such as calcite, whose decomposition temperature is greater than 800℃, are sufficient to withstand the high temperatures of molten aluminum alloys. Furthermore, the density of aluminum alloys is much lower than that of steel; therefore, castables used for aluminum alloy casting do not need to have very high strength, and lightweight, heat-insulating raw materials can be used. Therefore, there is an urgent need to research a lightweight, heat-insulating, and non-stick aluminum material suitable for use in the aluminum casting process. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a non-stick aluminum non-fired ceramic aggregate, its preparation method, and its application.

[0006] To achieve the objectives of this invention, the technical solution adopted is as follows:

[0007] The first aspect of the present invention provides a non-stick aluminum-free ceramsite, which is prepared from the following raw materials in parts by weight: 65-75 parts steel slag powder, 3-8 parts high-alumina cement, 20-30 parts glass powder, 1.5-3 parts anti-alumina-sticking agent, and 15-25 parts water.

[0008] According to the above-mentioned non-stick aluminum non-fired ceramic granules, preferably, the anti-sticking aluminum agent is composed of magnesium fluoride, calcium fluoride, barium carbonate and barium sulfate.

[0009] According to the above-mentioned non-stick aluminum non-fired ceramsite, preferably, the mass ratio of magnesium fluoride, calcium fluoride, barium carbonate and barium sulfate in the anti-sticking aluminum agent is (5-10):(5-10):(3-6):(2-4); more preferably, the mass ratio of magnesium fluoride, calcium fluoride, barium carbonate and barium sulfate is 6:6:5:3.

[0010] According to the above-mentioned non-stick aluminum-free ceramsite, preferably, the glass powder is sodium-calcium silicate glass powder, and the CaO content in the steel slag powder is ≥40%.

[0011] According to the above-mentioned non-stick aluminum non-fired ceramsite, preferably, the particle size of the glass powder is ≤150μm, the particle size of the steel slag powder is ≤75μm, the particle size of the anti-sticking aluminum agent is ≤75μm; and the particle size of the non-stick aluminum non-fired ceramsite is 1~10mm.

[0012] The non-stick aluminum-free ceramsite described above is preferably prepared from the following raw materials in parts by weight: 70 parts steel slag powder, 5 parts high-alumina cement, 25 parts glass powder, 2.5 parts anti-sticking aluminum agent, and 20 parts water.

[0013] A second aspect of the present invention provides a method for preparing the non-stick aluminum-free ceramsite described in the first aspect above, comprising the following steps:

[0014] (1) Steel slag, high-alumina cement, glass powder, anti-alumina adhesive and water are mixed evenly and then granulated to obtain granular material;

[0015] (2) The granules prepared in step (1) are subjected to pre-curing and carbon mineralization curing in sequence to obtain non-stick aluminum non-fired ceramic particles; the carbon mineralization curing operation is as follows: the pre-cured granules are cured in a gas atmosphere with CO2 volume concentration ≥30%.

[0016] According to the above preparation method, preferably, the temperature of carbon mineralization curing in step (2) is 10-40℃ and the time of carbon mineralization curing is 24-48h.

[0017] According to the above preparation method, preferably, the gas in step (2) is kiln exhaust gas.

[0018] According to the above preparation method, preferably, the pre-curing operation in step (2) is to place the granules in an environment with a temperature of 25-40°C and a relative humidity of 40%-60% for 12-48 hours.

[0019] The third aspect of the present invention provides the application of the non-stick aluminum-free ceramsite described in the first aspect in refractory castables.

[0020] According to the above application, preferably, the refractory castable is a refractory castable for aluminum melting and casting.

[0021] According to the above application, preferably, the non-stick aluminum non-fired ceramsite is used as an aggregate for refractory castables.

[0022] The fourth aspect of the present invention provides a non-stick aluminum refractory castable, wherein the non-stick aluminum refractory castable contains the non-stick aluminum non-fired ceramsite described in the first aspect above.

[0023] According to the above-mentioned non-stick aluminum refractory castable, preferably, the non-stick aluminum refractory castable is a refractory castable for aluminum melting and casting.

[0024] According to the above application, preferably, the non-stick aluminum non-fired ceramsite is used as aggregate for non-stick aluminum refractory castable.

[0025] Compared with the prior art, the positive and beneficial effects achieved by the present invention are as follows:

[0026] (1) This invention uses steel slag powder, high alumina cement, glass powder, anti-alumina sticking agent and water as raw materials to prepare non-stick aluminum non-fired ceramsite. Aluminate cement can provide basic strength for ceramsite blanks. During the carbon mineralization curing process, steel slag powder can undergo carbon mineralization reaction to generate calcium carbonate and amorphous silica gel, which further provides higher strength for ceramsite. When sodium calcium silicate glass powder is heated to above the glass transition temperature, viscous flow will begin and densification behavior will occur, which can enhance the ability of non-stick aluminum non-fired ceramsite to resist aluminum melt wetting. Moreover, sodium calcium silicate glass powder and anti-alumina sticking agent can play a synergistic role, further enhancing the anti-alumina sticking performance. The refractory castable for aluminum casting prepared with this ceramsite has strong resistance to aluminum melt wetting.

[0027] (2) In this invention, magnesium fluoride, calcium fluoride, barium carbonate and barium sulfate are compounded in a mass ratio of (5-10):(5-10):(3-6):(2-4) as an anti-aluminum-adhesion agent. The compounding of magnesium fluoride, calcium fluoride, barium carbonate and barium sulfate enables it to react with the molten aluminum that has penetrated into the pores of the refractory material preferentially over other components. Depending on the ratio, different forms of stable aluminum-fluorine compounds will be generated, forming a dense barrier layer, thereby effectively blocking further erosion by the molten aluminum and playing an anti-penetration role.

[0028] (3) In the preparation of non-stick aluminum non-fired ceramsite, the granulated material obtained by granulation is pre-cured in an environment with a temperature of 25-40℃ and a relative humidity of 40%-60%. Pre-curing can enable high-alumina cement to fully hydrate and generate hydration products, accelerate the hardening of cement, and provide the ceramsite with initial strength before carbon mineralization.

[0029] (4) This invention involves curing the pre-cured granules in kiln exhaust gas with a CO2 volume concentration ≥30%. This not only achieves effective utilization of the kiln exhaust gas, but also enables the ceramsite to harden rapidly and gain strength through carbon mineralization curing. Traditional sintering of ceramsite is a relatively complex process, requiring steps such as material selection, granulation, preheating, firing, and cooling. In contrast, carbon mineralization curing is simpler to operate and reduces energy consumption while achieving the same performance. Moreover, during the carbon mineralization curing process, the granules can absorb sulfur oxides, nitrogen oxides, and carbon dioxide gases from the exhaust gas, resulting in good low-carbon emission reduction benefits.

[0030] (5) The bulk density of the non-stick aluminum-free ceramsite prepared by this invention is 750-900 kg / m³. 3 The apparent density is 1100–1400 kg / m³. 3 The compressive strength of the cylinder is 10-16 MPa, and the water absorption rate after 2 hours is 6-8%. This demonstrates that the non-stick aluminum-free ceramsite prepared by this invention has the advantages of being lightweight, high-strength, and having low water absorption, and can be used as a substitute aggregate for refractory castables.

[0031] (6) When using the non-stick aluminum-free ceramsite of the present invention as aggregate for refractory castables, the density of the castable can be effectively reduced, and the weight of the castable can be reduced by about 25%. At the same time, the production cost of the castable can also be effectively reduced (the raw material cost of the castable can be reduced by more than 10%). Moreover, it can also improve the heat insulation performance of refractory castables and enhance the resistance of the castables to aluminum melt wetting. The prepared castables have the advantages of being lightweight, having good heat insulation performance, good heat preservation effect, being non-stick aluminum, and having strong resistance to aluminum melt erosion. This solves the problems of existing refractory castables used for aluminum casting having high bulk density, high thermal conductivity, and poor resistance to aluminum melt erosion.

[0032] (7) The non-stick aluminum non-fired ceramic pellets of the present invention use waste steel slag as raw material, which reduces production costs, realizes the secondary utilization of solid waste, reduces environmental pollution, and is green and environmentally friendly. Detailed Implementation

[0033] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0034] The following detailed description is exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0035] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. When the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, components, and / or combinations thereof. Experimental methods in the following embodiments that do not specify specific conditions employ conventional techniques in this art or follow the conditions recommended by the manufacturer; reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0036] Example 1: Discussion on the Dosage of Steel Slag Powder

[0037] To investigate the effect of steel slag powder dosage on the performance of non-stick aluminum non-fired ceramsite, this invention conducted Examples 1-1 to 1-6.

[0038] The specific contents of Examples 1-1 to 1-6 are as follows.

[0039] Example 1-1:

[0040] A non-sticking aluminum-free ceramsite is prepared from the following raw materials in parts by weight: 60 parts steel slag powder, 5 parts high-alumina cement, 25 parts glass powder, 2.5 parts anti-alumina-adhesion agent, and 20 parts water. The anti-alumina-adhesion agent is composed of magnesium fluoride, calcium fluoride, barium carbonate, and barium sulfate mixed in a mass ratio of 6:6:5:3. The glass powder is sodium-calcium silicate glass powder, and the CaO content in the steel slag powder is 45%. The particle size of the glass powder is ≤150μm, the particle size of the steel slag powder is ≤75μm, and the particle size of the anti-alumina-adhesion agent is ≤75μm.

[0041] The preparation method of the above-mentioned non-stick aluminum-free ceramsite is as follows:

[0042] (1) Mix steel slag, high-alumina cement, glass powder and anti-alumina agent evenly to obtain dry mix; add water to dry mix by spraying and mix evenly to obtain wet mix;

[0043] (2) Add the wet mixture to a disc granulator for granulation to obtain granules with a particle size of 10 mm;

[0044] (3) The granules prepared in step (2) are placed in an environment with a temperature of 25°C and a relative humidity of 60% for 24 hours for pre-curing; then the pre-cured granules are placed in a curing tank, the curing tank is first evacuated to below 1000Pa, and then kiln tail gas is introduced, and carbon mineralization curing is carried out at 10°C for 48 hours to obtain non-stick aluminum non-fired ceramsite; wherein, the CO2 volume concentration in the kiln tail gas is 30%.

[0045] The contents of Examples 1-2 to 1-6 are basically the same as those of Example 1-1, except that the amount of steel slag powder used is different. The amounts of steel slag powder used in the non-stick aluminum non-fired ceramsite formulations of Examples 1-2 to 1-6 are 65 parts, 70 parts, 75 parts, 80 parts, and 0 parts, respectively.

[0046] The bulk density, apparent density, cylinder compressive strength, water absorption, and anti-aluminum adhesion properties of the non-sticking aluminum-free ceramsite prepared in Examples 1-1 to 1-6 were tested. The anti-aluminum adhesion property was tested using the modified droplet method described in Qian Jianxing's article "Design and Application Research of Wetting Angle Measurement Device," measuring the wetting angle between the molten aluminum and the substrate refractory castable. A larger wetting angle indicates stronger anti-aluminum adhesion properties in the refractory castable made from this ceramsite. The test results are shown in Table 1.

[0047] The formula for the base refractory castable is as follows: 50 parts non-stick aluminum-free ceramsite, 13 parts tabular alumina (0.5-1mm particle size), 13 parts tabular alumina (0-0.5mm particle size), 9 parts tabular alumina (≤0.045mm particle size), 10 parts Al2O3 micro powder, 5 parts CAC cement, 1 part dispersant (added externally), and 4 parts water (added externally). The preparation method for the base refractory castable is as follows: Mix the non-stick aluminum-free ceramsite, tabular alumina, Al2O3 micro powder, CAC cement, and dispersant in a mixer until homogeneous (dry mixing for 1 minute) to obtain a dry powder. Slowly pour water into the homogeneous dry powder mixture within 1 minute, stirring until a uniform paste is formed. Quickly pour the prepared paste into a mold. During the pouring process, ensure uniform compaction and avoid air bubbles and voids. After pouring, cure for 24 hours before demolding.

[0048] Table 1. Effect of steel slag powder dosage on the properties of non-stick aluminum-free ceramsite

[0049]

[0050] As shown in Table 1, the compressive strength of the ceramsite gradually increases with the increase of steel slag powder content. When the steel slag powder content exceeds 70 parts, the change in compressive strength is not significant. Moreover, with the increase of steel slag powder content, the bulk density, apparent density, and anti-alumina adhesion of the ceramsite all show a trend of first decreasing and then increasing. However, excessively high bulk density and apparent density do not meet the purpose of lightweighting. Therefore, when the steel slag powder content is between 65 and 75 parts, ceramsite with better comprehensive performance can be obtained, and the preferred content is 70 parts.

[0051] Example 2: Discussion on the Dosage of High-Alumina Cement

[0052] To investigate the effect of high-alumina cement content on the performance of non-stick aluminum-bearing ceramsite, Examples 2-1 to 2-6 were conducted in this invention. The specific details of Examples 2-1 to 2-5 are as follows.

[0053] Example 2-1:

[0054] A non-sticking aluminum-free ceramsite is prepared from the following raw materials in parts by weight: 70 parts steel slag powder, 1 part high-alumina cement, 25 parts glass powder, 2.5 parts anti-alumina-adhesion agent, and 20 parts water. The anti-alumina-adhesion agent is composed of magnesium fluoride, calcium fluoride, barium carbonate, and barium sulfate mixed in a mass ratio of 6:6:5:3. The glass powder is sodium-calcium silicate glass powder, and the CaO content in the steel slag powder is 45%. The particle size of the glass powder is ≤150μm, the particle size of the steel slag powder is ≤75μm, and the particle size of the anti-alumina-adhesion agent is ≤75μm.

[0055] The preparation method of the above-mentioned non-stick aluminum-free ceramsite is as follows:

[0056] (1) Mix steel slag, high-alumina cement, glass powder and anti-alumina agent evenly to obtain dry mix; add water to dry mix by spraying and mix evenly to obtain wet mix;

[0057] (2) Add the wet mixture to a disc granulator for granulation to obtain granules with a particle size of 10 mm;

[0058] (3) The granules prepared in step (2) are placed in an environment with a temperature of 25°C and a relative humidity of 60% for 24 hours for pre-curing; then the pre-cured granules are placed in a curing tank, the curing tank is first evacuated to below 1000Pa, and then kiln tail gas is introduced, and carbon mineralization curing is carried out at 10°C for 48 hours to obtain non-stick aluminum non-fired ceramsite; wherein, the CO2 volume concentration in the kiln tail gas is 30%.

[0059] Examples 2-2 to 2-5 are basically the same as Example 2-1, except that the amount of high-alumina cement used is different. The amounts of high-alumina cement used in the non-stick aluminum-free ceramsite formulations of Examples 2-1 to 2-5 are 3 parts, 8 parts, 10 parts, and 0 parts, respectively.

[0060] The bulk density, apparent density, cylinder compressive strength, water absorption rate, and anti-aluminum adhesion properties of the non-stick aluminum-free ceramsite prepared in Examples 2-1 to 2-5 were tested, and the test results are shown in Table 2.

[0061] Table 2. Effect of high-alumina cement dosage on the properties of non-stick aluminum-coated ceramsite

[0062]

[0063] As shown in Table 2, when the amount of high-alumina cement is 3 to 8 parts, the prepared non-alumina-resistant non-fired ceramsite has moderate bulk density and apparent density, high compressive strength, low water absorption, and good resistance to aluminum adhesion. Therefore, the preferred amount of high-alumina cement is 3 to 8 parts, and more preferably 5 parts.

[0064] Example 3: Discussion on the Dosage of Glass Powder

[0065] In order to study the effect of glass powder dosage on the performance of non-stick aluminum non-fired ceramsite, this invention conducted Examples 3-1 to 3-5.

[0066] The specific contents of Examples 3-2 to 3-5 are as follows.

[0067] Example 3-1:

[0068] A non-sticking aluminum-free ceramsite is prepared from the following raw materials in parts by weight: 70 parts steel slag powder, 5 parts high-alumina cement, 15 parts glass powder, 2.5 parts anti-alumina-adhesion agent, and 20 parts water. The anti-alumina-adhesion agent is composed of magnesium fluoride, calcium fluoride, barium carbonate, and barium sulfate mixed in a mass ratio of 6:6:5:3. The glass powder is sodium-calcium silicate glass powder, and the CaO content in the steel slag powder is 45%. The particle size of the glass powder is ≤150μm, the particle size of the steel slag powder is ≤75μm, and the particle size of the anti-alumina-adhesion agent is ≤75μm.

[0069] The preparation method of the above-mentioned non-stick aluminum-free ceramsite is as follows:

[0070] (1) Mix steel slag, high-alumina cement, glass powder and anti-alumina agent evenly to obtain dry mix; add water to dry mix by spraying and mix evenly to obtain wet mix;

[0071] (2) Add the wet mixture to a disc granulator for granulation to obtain granules with a particle size of 10 mm;

[0072] (3) The granules prepared in step (2) are placed in an environment with a temperature of 25°C and a relative humidity of 60% for 24 hours for pre-curing; then the pre-cured granules are placed in a curing tank, the curing tank is first evacuated to below 1000Pa, and then kiln tail gas is introduced, and carbon mineralization curing is carried out at 10°C for 48 hours to obtain non-stick aluminum non-fired ceramsite; wherein, the CO2 volume concentration in the kiln tail gas is 30%.

[0073] Examples 3-2 to 3-5 are basically the same as Example 3-1, except that the amount of glass powder used is different. The amounts of glass powder used in the non-stick aluminum non-fired ceramsite formulations of Examples 3-2 to 3-5 are 20 parts, 30 parts, 35 parts, and 0 parts, respectively.

[0074] The bulk density, apparent density, cylinder compressive strength, water absorption rate, and anti-aluminum adhesion properties of the non-stick aluminum-free ceramsite prepared in Examples 3-1 to 3-5 were tested, and the test results are shown in Table 3.

[0075] Table 3. Effect of glass powder dosage on the properties of non-stick aluminum-free ceramsite

[0076]

[0077] As shown in Table 3, the ceramsite prepared without glass powder has poor resistance to aluminum adhesion. As the amount of glass powder increases, the resistance to aluminum adhesion of the ceramsite gradually improves. When the amount of glass powder is 20 to 30 parts, the ceramsite has good resistance to aluminum adhesion and high compressive strength. Therefore, the preferred amount of glass powder is 20 to 30 parts, and more preferably 25 parts.

[0078] Example 4: Discussion on the dosage of anti-adhesion aluminum agent

[0079] To investigate the effect of the amount of anti-adhesion aluminum agent on the performance of non-adhesive aluminum-free ceramsite, Examples 4-1 to 4-6 of this invention were conducted. The specific contents of Examples 4-2 to 4-7 are as follows.

[0080] Example 4-1:

[0081] A non-sticking aluminum-free ceramsite is prepared from the following raw materials in parts by weight: 70 parts steel slag powder, 5 parts high-alumina cement, 25 parts glass powder, 1 part anti-alumina-adhesion agent, and 20 parts water. The anti-alumina-adhesion agent is composed of magnesium fluoride, calcium fluoride, barium carbonate, and barium sulfate mixed in a mass ratio of 6:6:5:3. The glass powder is sodium-calcium silicate glass powder, and the CaO content in the steel slag powder is 45%. The particle size of the glass powder is ≤150μm, the particle size of the steel slag powder is ≤75μm, and the particle size of the anti-alumina-adhesion agent is ≤75μm.

[0082] The preparation method of the above-mentioned non-stick aluminum-free ceramsite is as follows:

[0083] (1) Mix steel slag, high-alumina cement, glass powder and anti-alumina agent evenly to obtain dry mix; add water to dry mix by spraying and mix evenly to obtain wet mix;

[0084] (2) Add the wet mixture to a disc granulator for granulation to obtain granules with a particle size of 10 mm;

[0085] (3) The granules prepared in step (2) are placed in an environment with a temperature of 25°C and a relative humidity of 60% for 24 hours for pre-curing; then the pre-cured granules are placed in a curing tank, the curing tank is first evacuated to below 1000Pa, and then kiln tail gas is introduced, and carbon mineralization curing is carried out at 10°C for 48 hours to obtain non-stick aluminum non-fired ceramsite; wherein, the CO2 volume concentration in the kiln tail gas is 30%.

[0086] Examples 4-2 to 4-6 are basically the same as Example 4-1, except that the amount of anti-aluminum sticking agent used is different. The amounts of anti-aluminum sticking agent used in the non-aluminum-sticking non-fired ceramsite formulations of Examples 4-2 to 4-6 are 1.5 parts, 2.0 parts, 3.0 parts, 3.5 parts, and 0 parts, respectively.

[0087] The contents of Examples 4-7 are basically the same as those of Example 4-1, except that the amount of glass powder is 0 parts and the amount of anti-adhesion aluminum agent is 0 parts (that is, the non-adhesion aluminum-free ceramsite formula does not contain glass powder and anti-adhesion aluminum agent).

[0088] The bulk density, apparent density, cylinder compressive strength, water absorption rate, and anti-aluminum adhesion properties of the non-stick aluminum-free ceramsite prepared in Examples 4-1 to 4-7 were tested, and the test results are shown in Table 4.

[0089] Table 4. Effect of anti-adhesion aluminum agent dosage on the properties of non-adhesive aluminum-free ceramsite

[0090]

[0091] Table 4 shows that without the addition of glass powder and anti-aluminum adhesion agent, the ceramsite exhibits poor anti-aluminum adhesion properties, with a wetting angle of only 86° between the molten aluminum and the base refractory castable. However, with the addition of both glass powder and anti-aluminum adhesion agent, the ceramsite demonstrates significantly better anti-aluminum adhesion properties compared to adding either glass powder or the anti-aluminum adhesion agent alone. This indicates that glass powder and anti-aluminum adhesion agent have a synergistic effect, jointly enhancing the anti-aluminum adhesion performance of the non-aluminum-adhesive, non-fired ceramsite. Furthermore, when the amount of anti-aluminum adhesion agent is between 1.5 and 3 parts, the prepared ceramsite exhibits good anti-aluminum adhesion properties, high compressive strength, and low water absorption. Therefore, the preferred amount of anti-aluminum adhesion agent is 1.5 to 3 parts, and more preferably 2.5 parts.

[0092] Example 5: Investigation of CO2 volume concentration in exhaust gas during carbon mineralization curing process

[0093] To investigate the effect of CO2 volume concentration in the tail gas during the carbonization curing process on the performance of non-stick aluminum-free ceramsite, Examples 5-1 to 5-5 were conducted in this invention. The specific contents of Examples 5-2 to 5-5 are as follows.

[0094] Example 5-1:

[0095] A non-sticking aluminum-free ceramsite is prepared from the following raw materials in parts by weight: 70 parts steel slag powder, 5 parts high-alumina cement, 25 parts glass powder, 2.5 parts anti-alumina-adhesion agent, and 20 parts water. The anti-alumina-adhesion agent is composed of magnesium fluoride, calcium fluoride, barium carbonate, and barium sulfate mixed in a mass ratio of 6:6:5:3. The glass powder is sodium-calcium silicate glass powder, and the CaO content in the steel slag powder is 45%. The particle size of the glass powder is ≤150μm, the particle size of the steel slag powder is ≤75μm, and the particle size of the anti-alumina-adhesion agent is ≤75μm.

[0096] The preparation method of the above-mentioned non-stick aluminum-free ceramsite is as follows:

[0097] (1) Mix steel slag, high-alumina cement, glass powder and anti-alumina agent evenly to obtain dry mix; add water to dry mix by spraying and mix evenly to obtain wet mix;

[0098] (2) Add the wet mixture to a disc granulator for granulation to obtain granules with a particle size of 10 mm;

[0099] (3) The granules prepared in step (2) are placed in an environment with a temperature of 25℃ and a relative humidity of 60% for 24 hours for pre-curing; then the pre-cured granules are placed in a curing tank, the curing tank is first evacuated to below 1000Pa, and then kiln tail gas is introduced, and carbon mineralization curing is carried out at 10℃ for 48 hours to obtain non-stick aluminum non-fired ceramsite; wherein, the CO2 volume concentration in the kiln tail gas is 25%.

[0100] Examples 5-2 to 5-5 are basically the same as Example 5-1, except that the CO2 volume concentration in the kiln exhaust gas is different during the carbonization curing of non-stick aluminum-free ceramsite. In Examples 5-2 to 5-5, the CO2 volume concentrations in the kiln exhaust gas during the carbonization curing of non-stick aluminum-free ceramsite are 35%, 40%, 45%, and 0%, respectively.

[0101] The bulk density, apparent density, cylinder compressive strength, water absorption rate, and anti-aluminum adhesion properties of the non-stick aluminum-free ceramsite prepared in Examples 5-1 to 5-5 were tested, and the test results are shown in Table 5.

[0102] Table 5. Effect of CO2 volume concentration in carbon mineralization curing exhaust gas on the performance of non-stick aluminum-free ceramsite.

[0103]

[0104] As shown in Table 5, the compressive strength of the ceramsite gradually increases with the increase of CO2 volume concentration. However, when the CO2 volume concentration is 30%, the change in compressive strength is not significant. Therefore, in order to save energy and reduce costs, the CO2 volume concentration is preferably 30%.

[0105] Example 6: Discussion on carbon mineralization curing temperature

[0106] To investigate the effect of carbonization curing temperature on the properties of non-stick aluminum-free ceramsite, Examples 6-1 to 6-6 were conducted in this invention. The specific details of Examples 6-2 to 6-6 are as follows.

[0107] Example 6-1:

[0108] A non-sticking aluminum-free ceramsite is prepared from the following raw materials in parts by weight: 70 parts steel slag powder, 5 parts high-alumina cement, 25 parts glass powder, 2.5 parts anti-alumina-adhesion agent, and 20 parts water. The anti-alumina-adhesion agent is composed of magnesium fluoride, calcium fluoride, barium carbonate, and barium sulfate mixed in a mass ratio of 6:6:5:3. The glass powder is sodium-calcium silicate glass powder, and the CaO content in the steel slag powder is 45%. The particle size of the glass powder is ≤150μm, the particle size of the steel slag powder is ≤75μm, and the particle size of the anti-alumina-adhesion agent is ≤75μm.

[0109] The preparation method of the above-mentioned non-stick aluminum-free ceramsite is as follows:

[0110] (1) Mix steel slag, high-alumina cement, glass powder and anti-alumina agent evenly to obtain dry mix; add water to dry mix by spraying and mix evenly to obtain wet mix;

[0111] (2) Add the wet mixture to a disc granulator for granulation to obtain granules with a particle size of 10 mm;

[0112] (3) The granules prepared in step (2) are placed in an environment with a temperature of 25°C and a relative humidity of 60% for 24 hours for pre-curing; then the pre-cured granules are placed in a curing tank, the curing tank is first evacuated to below 1000Pa, and then kiln tail gas is introduced, and carbon mineralization curing is carried out at 5°C for 48 hours to obtain non-stick aluminum non-fired ceramsite; wherein, the CO2 volume concentration in the kiln tail gas is 30%.

[0113] Examples 6-2 to 6-6 are basically the same as Example 6-1, except that the carbon mineralization curing temperature of the non-stick aluminum-free ceramsite is different. The carbon mineralization curing temperatures of the non-stick aluminum-free ceramsite in Examples 6-2 to 6-6 are 10℃, 20℃, 30℃, 40℃, and 50℃, respectively.

[0114] The bulk density, apparent density, cylinder compressive strength, water absorption rate, and anti-aluminum adhesion properties of the non-stick aluminum-free ceramsite prepared in Examples 6-1 to 6-6 were tested, and the test results are shown in Table 6.

[0115] Table 6. Effect of carbonization curing temperature on the properties of non-stick aluminum-free ceramsite

[0116]

[0117] As shown in Table 6, the compressive strength of the ceramsite first increases and then decreases with increasing carbonization temperature. This is because a large amount of heat is released during the carbonation reaction, and high temperatures are not conducive to the development of the ceramsite's strength. Therefore, the preferred carbonization curing temperature is 10–40℃, and more preferably 10℃.

[0118] Example 7: Discussion on Pre-curing Humidity

[0119] In order to study the effect of pre-curing humidity on the performance of non-stick aluminum non-fired ceramsite, this invention conducted Examples 7-1 to 7-5.

[0120] The specific contents of Examples 7-2 to 7-5 are as follows.

[0121] Example 7-1:

[0122] A non-sticking aluminum-free ceramsite is prepared from the following raw materials in parts by weight: 70 parts steel slag powder, 5 parts high-alumina cement, 25 parts glass powder, 2.5 parts anti-alumina-adhesion agent, and 20 parts water. The anti-alumina-adhesion agent is composed of magnesium fluoride, calcium fluoride, barium carbonate, and barium sulfate mixed in a mass ratio of 6:6:5:3. The glass powder is sodium-calcium silicate glass powder, and the CaO content in the steel slag powder is 45%. The particle size of the glass powder is ≤150μm, the particle size of the steel slag powder is ≤75μm, and the particle size of the anti-alumina-adhesion agent is ≤75μm.

[0123] The preparation method of the above-mentioned non-stick aluminum-free ceramsite is as follows:

[0124] (1) Mix steel slag, high-alumina cement, glass powder and anti-alumina agent evenly to obtain dry mix; add water to dry mix by spraying and mix evenly to obtain wet mix;

[0125] (2) Add the wet mixture to a disc granulator for granulation to obtain granules with a particle size of 10 mm;

[0126] (3) The granules prepared in step (2) are placed in an environment with a temperature of 25℃ and a relative humidity of 30% for 24 hours for pre-curing; then the pre-cured granules are placed in a curing tank, the curing tank is first evacuated to below 1000Pa, and then kiln tail gas is introduced, and carbon mineralization curing is carried out at 10℃ for 48 hours to obtain non-stick aluminum non-fired ceramsite; wherein, the CO2 volume concentration in the kiln tail gas is 30%.

[0127] Examples 7-2 to 7-5 are basically the same as Example 7-1, except that the humidity during pre-curing of the non-stick aluminum-free ceramsite is different. The humidity during carbon mineralization curing of the non-stick aluminum-free ceramsite in Examples 7-2 to 7-5 are 40%, 50%, and 70%, respectively.

[0128] The bulk density, apparent density, cylinder compressive strength, water absorption rate, and anti-aluminum adhesion properties of the non-stick aluminum-free ceramsite prepared in Examples 7-1 to 7-5 were tested, and the test results are shown in Table 7.

[0129] Table 7. Effect of Pre-curing Humidity on the Properties of Non-stick Aluminum-free Ceramsite

[0130]

[0131] As shown in Table 7, with the increase of pre-curing humidity, the density, compressive strength, and water absorption rate of the ceramsite first increase and then decrease. When the pre-curing humidity is 40% to 60%, the resulting non-stick aluminum-free ceramsite has high compressive strength, low water absorption, and moderate density. Therefore, the preferred pre-curing humidity is 40% to 60%, and more preferably 60%. This is because low humidity leads to faster water evaporation, which is not conducive to subsequent carbon mineralization curing; high humidity slows down the hardening of high-alumina cement.

[0132] In summary, the above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may use the above technical content as inspiration to make changes or modifications. These are equivalent embodiments with variations. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the inventive concept are still within the protection scope of the claims of the present invention.

Claims

1. A non-stick aluminum-free ceramsite, characterized in that, It is prepared from the following raw materials in parts by weight: 65-75 parts steel slag powder, 3-8 parts high-alumina cement, 20-30 parts glass powder, 1.5-3 parts anti-aluminum-adhesion agent, and 15-25 parts water; the glass powder is sodium-calcium silicate glass powder; the anti-aluminum-adhesion agent is composed of magnesium fluoride, calcium fluoride, barium carbonate, and barium sulfate.

2. The non-stick aluminum-free ceramsite according to claim 1, characterized in that, The mass ratio of magnesium fluoride, calcium fluoride, barium carbonate and barium sulfate in the anti-adhesion aluminum agent is (5-10): (5-10): (3-6): (2-4).

3. The non-stick aluminum-free ceramsite according to claim 1 or 2, characterized in that, The CaO content in the steel slag powder is ≥40%; the particle size of the glass powder is ≤150μm; the particle size of the steel slag powder is ≤75μm; and the particle size of the anti-adhesion aluminum agent is ≤75μm.

4. A method for preparing non-stick aluminum-free ceramsite according to any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Steel slag powder, high alumina cement, glass powder, anti-alumina agent and water are mixed evenly and then granulated to obtain granular material; (2) The granules prepared in step (1) are subjected to pre-curing and carbon mineralization curing in sequence to obtain non-stick aluminum non-fired ceramic particles; the carbon mineralization curing operation is as follows: the pre-cured granules are cured in a gas atmosphere with CO2 volume concentration ≥30%.

5. The preparation method according to claim 4, characterized in that, The carbon mineralization curing temperature is 10–40°C, and the carbon mineralization curing time is 24–48 hours; the gas is kiln exhaust gas.

6. The preparation method according to claim 5, characterized in that, The pre-curing operation is as follows: place the granules in an environment with a temperature of 25-40℃ and a relative humidity of 40%-60% for 12-48 hours.

7. The application of the non-stick aluminum-free ceramsite as described in any one of claims 1 to 3 in refractory castables.

8. A non-stick aluminum refractory castable, characterized in that, It contains the non-stick aluminum non-fired ceramic pellets as described in any one of claims 1 to 3.

9. The non-stick aluminum refractory castable according to claim 8, characterized in that, It is composed of the following raw materials in parts by weight: 45-55 parts of non-stick aluminum non-fired ceramsite, 10-15 parts of tabular corundum with a particle size of 0.5-1mm, 10-15 parts of tabular corundum with a particle size of 0-0.5mm, 6-12 parts of tabular corundum with a particle size ≤0.045mm, 7-15 parts of Al2O3 micro powder, 3-7 parts of CAC cement, 0.5-3 parts of dispersant, and 3-8 parts of water.

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