Sol combined refractory castable for rotary hearth furnace and preparation method of sol combined refractory castable

Abstract

The invention discloses a sol-bonded refractory castable for a rotary hearth furnace and a preparation method of the sol-bonded refractory castable, the sol-bonded refractory castable comprises refractory aggregate, micro powder, a binding agent, a surfactant and a plasticizer, and the refractory aggregate comprises the following components in percentage by weight: 40-50% of high-alumina bauxite, 25-35% of corundum and 5-15% of silicon carbide; based on the total weight of the refractory aggregate, the micro powder comprises the following components in percentage by weight: 5-10% of aluminum oxide micro powder and 5-10% of micro silicon powder; based on the total weight of all solid raw materials, the binding agent comprises the following components in percentage by weight: 3-8% of silica sol; based on the total weight of all the solid raw materials, the percentage ratio of the components of the surfactant is 0.1-0.5%; and the plasticizer accounts for 1-3% of the total weight of all the solid raw materials. The refractory castable has the beneficial effects that the refractory castable has the following advantages that the refractory castable is stable in fire resistance and excellent in high-temperature resistance, and can be used for a long time under the high-temperature condition; and the thermal shock resistance stability is good, and the thermal shock effect of the rotary hearth furnace under rapid temperature change can be resisted.

Description

Technical Field

[0001] The invention relates to the field of refractory castables, and in particular to a sol-bonded refractory castable for a rotary hearth furnace and a preparation method thereof. Background Art

[0002] The rotary hearth furnace is a common metallurgical equipment used for melting and smelting metals. In the high temperature environment of the rotary hearth furnace, the refractory material has to withstand multiple forces such as high temperature, thermal shock and chemical erosion, so it needs to have refractory properties, thermal shock stability and chemical erosion resistance.

[0003] However, the refractory castables for rotary hearth furnaces on the market currently usually have problems such as unstable refractory performance, poor thermal shock resistance, and limited resistance to chemical corrosion, resulting in the refractory materials' post-firing compressive strength, post-firing flexural strength, post-firing linear change rate, and thermal stability times being unable to meet design and use requirements. Summary of the invention

[0004] The object of the present invention is to provide a sol-bonded refractory castable for a rotary hearth furnace and a preparation method thereof in order to solve the above-mentioned problems, as described in detail below.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a sol-bonded refractory castable for a rotary hearth furnace, comprising refractory aggregate, micropowder, a binder, a surfactant and a plasticizer;

[0007] The weight percentage ratio of the components of the refractory aggregate is: 40-50% high-alumina bauxite, 25-35% corundum, and 5-15% silicon carbide;

[0008] The weight of the components of the micro powder is based on the total amount of refractory aggregate and the percentage ratio is: 5-10% of alumina micro powder and 5-10% of micro silica powder;

[0009] The weight of the components of the binder is based on the total amount of all solid raw materials and the percentage ratio is: silica sol 3-8%;

[0010] The component weight of the surfactant is based on the total amount of all solid raw materials and the percentage ratio is: 0.1-0.5%;

[0011] The weight of the plasticizer component is based on the total amount of all solid raw materials and the percentage ratio is: 1-3%.

[0012] Preferably, the Al in the high alumina is 2 O 3 The content is ≥50%, and the particle size range is 10-0.1 mm, so as to ensure that the high-alumina bauxite particles are evenly distributed.

[0013] Preferably, Al in the corundum 2 O 3 The content is ≥95%, and the particle size range is 5-0mm, so that the refractory aggregate has good fire resistance and wear resistance.

[0014] Preferably, the SiC content in the silicon carbide is ≥95%, and particles with a particle size range of <0.5 mm account for more than half of the total mass of the silicon carbide, so as to enhance the chemical corrosion resistance.

[0015] Preferably, the particles with a particle size range of less than 0.074 mm in the alumina micropowder and the microsilica powder account for 85-95% of their respective total mass, so as to improve the sintering strength and density.

[0016] Preferably, the solid content of the silica sol is in the range of 20%-40% and the viscosity is moderate, so as to improve the high temperature strength and thermal shock resistance stability of the silica sol when used as a binder.

[0017] Preferably, the surfactant is polyethylene glycol, sodium lignin sulfonate or a mixture of the two, which is used to reduce surface tension and improve fluidity and demoulding properties.

[0018] Preferably, the plasticizer is carboxymethyl cellulose, clay or a mixture of the two, so as to maintain plasticity during stirring and construction.

[0019] The method for preparing the above-mentioned sol-bonded refractory castable for a rotary hearth furnace comprises the following steps:

[0020] a. Add the refractory aggregate into a mixing device in a certain proportion and mix to ensure uniform particle distribution;

[0021] b. Adding an appropriate amount of the binder to the mixed refractory aggregate, and continuing to stir evenly with the aid of a stirring device to form a cohesive castable;

[0022] c. Add the plasticizer to the stirring device and continue stirring to make the casting material have a certain plasticity;

[0023] d. Add surfactant to the mixing equipment and stir evenly to make the castable have better fluidity;

[0024] e. Pour the stirred castable into the construction site and compact it with a vibrating rod;

[0025] f. After the construction is completed, the castable should be left to solidify and cured for an appropriate period of time.

[0026] Preferably, the stirring equipment is a planetary mixer or equivalent equipment, the mixing time ranges from 5 to 15 minutes; the vibration frequency range of the vibrating rod is 50 to 316.7 Hz; the static curing time ranges from 24 to 48 hours, the curing environment is a ventilated environment with a temperature range of 20 to 35°C, and the curing time is 1 to 7 days.

[0027] The beneficial effects are: the refractory castable of the present invention has the following advantages:

[0028] 1. Stable fire resistance, excellent high temperature resistance, and can be used for a long time under high temperature conditions;

[0029] 2. Good thermal shock resistance and stability, able to withstand the thermal shock of the rotary hearth furnace under rapid temperature changes;

[0030] 3. Excellent chemical corrosion resistance, the surface of refractory castables is not easily corroded by molten metal;

[0031] 4. The castable has good fluidity and cold demoulding properties, which is convenient for construction. DETAILED DESCRIPTION

[0032] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0033] The present invention provides a sol-bonded refractory castable for a rotary hearth furnace, comprising refractory aggregate, micropowder, binder, surfactant and plasticizer; wherein the weight percentage ratio of the components of the refractory aggregate is: 40-50% of high-alumina bauxite, 25-35% of corundum, and 5-15% of silicon carbide; the weight of the components of the micropowder is based on the total amount of the refractory aggregate and the percentage ratio is: 5-10% of alumina micropowder and 5-10% of microsilica powder; the weight of the components of the binder is based on the total amount of all solid raw materials and the percentage ratio is: 3-8% of silica sol; the weight of the components of the surfactant is based on the total amount of all solid raw materials and the percentage ratio is: 0.1-0.5%; the weight of the components of the plasticizer is based on the total amount of all solid raw materials and the percentage ratio is: 1-3%.

[0034] The above scheme is optimized as follows: 2 O 3 The content is ≥50%, and the particle size range is 10-0.1mm, which is used to ensure that the high-alumina bauxite particles are evenly distributed. 2 O 3The content is ≥95%, and the particle size range is 5-0mm, so that the refractory aggregate has good fire resistance and wear resistance. The SiC content in the silicon carbide is ≥95%, and the particles with a particle size range of <0.5mm account for more than half of the total mass of the silicon carbide, so as to enhance the resistance to chemical erosion. The particles with a particle size range of <0.074mm in the alumina micropowder and the microsilica powder account for 85-95% of their respective total mass, so as to improve the sintering strength and density. The solid content of the silica sol ranges from 20% to 40%, and the viscosity is moderate, so that the silica sol is used as a binder to improve the high temperature strength and thermal shock stability. The surfactant is polyethylene glycol, sodium lignin sulfonate or a mixture of the two, which is used to reduce surface tension and improve fluidity and demolding performance. The plasticizer is carboxymethyl cellulose, clay or a mixture of the two, which is used to maintain plasticity during mixing and construction.

[0035] Specifically speaking of the preparation method, a preparation method of a sol-bonded refractory castable for a rotary hearth furnace comprises the following steps:

[0036] a. Add the refractory aggregate into a mixing device in a certain proportion and mix to ensure uniform particle distribution;

[0037] b. Adding an appropriate amount of the binder to the mixed refractory aggregate, and continuing to stir evenly with the aid of a stirring device to form a cohesive castable;

[0038] c. Add the plasticizer to the stirring device and continue stirring to make the casting material have a certain plasticity;

[0039] d. Add surfactant to the mixing equipment and stir evenly to make the castable have better fluidity;

[0040] e. Pour the stirred castable into the construction site and compact it with a vibrating rod;

[0041] f. After the construction is completed, the castable should be left to solidify and cured for an appropriate period of time.

[0042] The following more specific optimizations are made for the above preparation method. Specifically, during the preparation process of the castable, each component needs to be gradually added to the mixing equipment in order and fully mixed to ensure good bonding between the components and the overall performance of the castable. The mixing equipment uses a planetary mixer or equivalent equipment. The mixing power of the mixing equipment is determined according to the model and capacity of the mixer, usually between several kilowatts and tens of kilowatts, such as 75kW. At the same time, the mixing speed of the mixing equipment should be adjustable. The recommended revolution speed range is 50-150 rpm, and the rotation speed is higher than this value. It is adjusted according to the material characteristics. The mixing time is controlled at 5-15 minutes until the mixing is uniform.

[0043] When the castable material is constructed after mixing, pour the mixed castable material into the construction site and use a vibrating rod to compact it. The vibration frequency of the vibrating rod should be selected between 50-316.7Hz, which is determined according to the aggregate particle size and performance requirements of the castable. The amplitude should be controlled between a few millimeters and more than ten millimeters, coordinated with the vibration frequency to achieve the best compaction effect.

[0044] After the castable is prepared, it needs to be properly cured and maintained to ensure that it reaches the best performance before construction. Specifically, the curing time of the castable is about 24-48 hours, which is adjusted according to the ambient temperature and castable formula. After curing, the castable is moved to a well-ventilated, stable temperature (recommended 20-35℃), vibration-free environment for curing, which usually lasts 1-7 days.

[0045] Embodiment 1:

[0046] A sol-bonded refractory castable for a rotary hearth furnace comprises a refractory aggregate, a micropowder, a binder, a surfactant and a plasticizer; wherein the weight percentage ratio of the components of the refractory aggregate is: 40% high-alumina bauxite, 35% corundum, and 5% silicon carbide; the weight of the components of the micropowder is based on the total amount of the refractory aggregate and the percentage ratio is: 5% alumina micropowder and 5% microsilica powder; the weight of the components of the binder is based on the total amount of all solid raw materials and the percentage ratio is: 8% silica sol; the weight of the components of the surfactant is based on the total amount of all solid raw materials and the percentage ratio is: 0.5%; the weight of the components of the plasticizer is based on the total amount of all solid raw materials and the percentage ratio is: 1.5%.

[0047] Embodiment 2:

[0048] A sol-bonded refractory castable for a rotary hearth furnace comprises a refractory aggregate, a micropowder, a binder, a surfactant and a plasticizer; wherein the weight percentage ratio of the components of the refractory aggregate is: 50% high-alumina bauxite, 25% corundum, and 10% silicon carbide; the weight of the components of the micropowder is based on the total amount of the refractory aggregate and the percentage ratio is: 5% alumina micropowder and 5% microsilica powder; the weight of the components of the binder is based on the total amount of all solid raw materials and the percentage ratio is: 3% silica sol; the weight of the components of the surfactant is based on the total amount of all solid raw materials and the percentage ratio is: 0.3%; the weight of the components of the plasticizer is based on the total amount of all solid raw materials and the percentage ratio is: 1.7%.

[0049] Embodiment three:

[0050] A sol-bonded refractory castable for a rotary hearth furnace comprises a refractory aggregate, a micropowder, a binder, a surfactant and a plasticizer; wherein the weight percentage ratio of the components of the refractory aggregate is: 45% of high-alumina bauxite, 30% of corundum and 5% of silicon carbide; the weight of the components of the micropowder is based on the total amount of the refractory aggregate and the percentage ratio is: 7.5% of alumina micropowder and 7.5% of microsilica powder; the weight of the components of the binder is based on the total amount of all solid raw materials and the percentage ratio is: 3% of silica sol; the weight of the components of the surfactant is based on the total amount of all solid raw materials and the percentage ratio is: 0.25%; the weight of the components of the plasticizer is based on the total amount of all solid raw materials and the percentage ratio is: 1.75%.

[0051] In actual preparation, the castable prepared according to the above embodiment was tested and verified for the following test indicators, and the specific data are as follows:

[0052]

[0053] From the above data, it can be seen that the castable prepared in accordance with the present application has its post-firing compressive strength, post-firing flexural strength, post-firing linear change rate and thermal stability times all effectively and reliably guaranteed, and can better meet the refractory requirements of the rotary hearth furnace for the castable.

[0054] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A sol-bonded refractory castable for a rotary hearth furnace, characterized in that: It includes refractory aggregate, micro powder, binder, surfactant and plasticizer; The weight percentage ratio of the components of the refractory aggregate is: 40-50% high-alumina bauxite, 25-35% corundum, and 5-15% silicon carbide; The weight of the components of the micro powder is based on the total amount of refractory aggregate and the percentage ratio is: 5-10% of alumina micro powder and 5-10% of micro silica powder; The weight of the components of the binder is based on the total amount of all solid raw materials and the percentage ratio is: silica sol 3-8%; The component weight of the surfactant is based on the total amount of all solid raw materials and the percentage ratio is: 0.1-0.5%; The weight of the plasticizer component is based on the total amount of all solid raw materials and the percentage ratio is: 1-3%.

2. The sol-bonded refractory castable for a rotary hearth furnace according to claim 1, characterized in that: The Al2O3 content in the high-alumina bauxite is ≥50%, and the particle size range is 10-0.1 mm, so as to ensure that the high-alumina bauxite particles are evenly distributed.

3. The sol-bonded refractory castable for a rotary hearth furnace according to claim 2, characterized in that: The Al2O3 content in the corundum is ≥95%, and the particle size range is 5-0 mm, so that the refractory aggregate has good fire resistance and wear resistance.

4. The sol-bonded refractory castable for a rotary hearth furnace according to claim 3, characterized in that: The SiC content in the silicon carbide is ≥95%, and particles with a particle size range of <0.5 mm account for more than half of the total mass of the silicon carbide, so as to enhance the chemical corrosion resistance.

5. The sol-bonded refractory castable for a rotary hearth furnace according to claim 1, characterized in that: The particles with a particle size range of less than 0.074 mm in the alumina micropowder and the microsilica powder account for 85-95% of their respective total masses, so as to improve the sintering strength and density.

6. The sol-bonded refractory castable for a rotary hearth furnace according to claim 1, characterized in that: The solid content of the silica sol is in the range of 20%-40% and the viscosity is moderate, so that the silica sol can be used as a binder to improve the high temperature strength and thermal shock resistance stability.

7. The sol-bonded refractory castable for a rotary hearth furnace according to claim 1, characterized in that: The surfactant is polyethylene glycol, sodium lignin sulfonate or a mixture of the two, which is used to reduce surface tension and improve fluidity and demoulding performance.

8. The sol-bonded refractory castable for a rotary hearth furnace according to claim 1, characterized in that: The plasticizer is carboxymethyl cellulose, clay or a mixture of the two, and is used to maintain plasticity during the mixing and construction process.

9. The method for preparing a sol-bonded refractory castable for a rotary hearth furnace according to any one of claims 1 to 8, characterized in that: The steps include: a. Add the refractory aggregate into a mixing device in a certain proportion and mix to ensure uniform particle distribution; b. Adding an appropriate amount of the binder to the mixed refractory aggregate, and continuing to stir evenly with the aid of a stirring device to form a cohesive castable; c. Add the plasticizer to the stirring device and continue stirring to make the casting material have a certain plasticity; d. Add surfactant to the mixing equipment and stir evenly to make the castable have better fluidity; e. Pour the stirred castable into the construction site and compact it with a vibrating rod; f. After the construction is completed, the castable should be left to solidify and cured for an appropriate period of time.

10. The sol-bonded refractory castable for a rotary hearth furnace according to claim 9, characterized in that: The mixing equipment is a planetary mixer or equivalent equipment, and the mixing time ranges from 5 to 15 minutes; the vibration frequency range of the vibrating rod is 50 to 316.7 Hz; the static curing time ranges from 24 to 48 hours, the curing environment is a ventilated environment with a temperature range of 20 to 35°C, and the curing time is 1 to 7 days.

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