Modified corundum brick for key part of incineration system of hazardous waste furnace and preparation method of modified corundum brick

Abstract

The invention relates to a modified corundum brick for a key part of a hazardous waste furnace incineration system, which comprises the following components in percentage by mass: 6-9% of ZrO and 90-95% of fused corundum, wherein the fused alumina comprises the following components in percentage by weight: 93%-94% of Al2O3, 0.1%-0.2% of SiO2 and 5%-6.5% of Na2O, and the Al2O3 comprises more than 99% of beta-Al2O3. The modified corundum brick has the beneficial effects that the beta-Al2O3 is firstly used as a main material to prepare the fused corundum, then the zirconium oxide is added into the fused corundum to serve as an auxiliary agent, and a mixture of the fused corundum and the zirconium oxide is sintered, so that the obtained modified corundum brick has excellent heat preservation and heat insulation performance, excellent wear resistance, high-temperature stability and thermal shock resistance and relatively high mechanical strength; and thermal shock resistance: due to the phase change toughening effect of zirconium oxide, the modified fused corundum shows better crack propagation resistance during rapid heating and cooling. And mechanical strength: after the zirconium oxide is added, the overall mechanical strength of the material is improved, and particularly the fracture toughness is remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of hazardous waste furnace incineration systems, and in particular relates to a modified corundum brick used for key parts of a hazardous waste furnace incineration system and a preparation method thereof. Background Art

[0002] The incinerator area is divided into the feeding area, drying area, combustion area and burnout area. Each area varies according to the aspect ratio or size of the rotary kiln, material characteristics and operating process. There is material explosion in the feeding area, the flue gas temperature is high, the solid waste temperature is lower than 700℃, the refractory lining material is mainly corroded by acid and alkali liquid and mechanical wear, and the material resistance to thermal shock performance is required to be high; the temperature of the drying area is 700-1000℃, the water vapor erosion in this area is serious, and the mechanical wear of the material is relatively not serious; the temperature of the combustion area can reach 1000-1400℃, some materials melt at high temperature, the wear resistance of the refractory material decreases at high temperature, and it is seriously corroded by high temperature slag; the burnout area is close to the discharge port, the temperature is lowered, and the wear and erosion of the material are reduced. Some rotary kilns with a small aspect ratio have almost no burnout section during the incineration process, and the high-temperature ash or slag directly enters the quenching system through the kiln mouth.

[0003] The three commonly used refractory materials in the combustion zone are chrome-zirconium-corundum, corundum-mullite and high-aluminum. Among them, chrome-zirconium-corundum has the best corrosion resistance, followed by corundum-mullite, and high-aluminum is the worst. Studies have shown that the good corrosion resistance of chrome-zirconium-corundum materials is mainly due to the formation of solid solutions or eutectics between chromium oxide and oxides, which improves the material's resistance to slag corrosion and increases the slag viscosity (8-10). Corundum-mullite and high-aluminum refractory materials can be used in ash-slag rotary kiln incinerators, but chrome-zirconium-corundum materials or modified corundum materials are recommended for the high-temperature combustion zone of slag-type rotary kiln incinerators for better results.

[0004] A large amount of nepheline minerals are produced in the residual bricks after the use of chrome-zirconium corundum bricks in the combustion area of ​​the incinerator, and hexavalent chromium is detected. In addition, the microstructural analysis of the residual bricks shows that there are more glass phases inside the dense refractory bricks, and the sodium salts in the materials react with the refractory materials, corroding and causing damage to the refractory materials. The nepheline minerals in refractory bricks are low-melting-point phases, which are mainly formed by the sodium salts in the materials penetrating into the refractory bricks and reacting with Al2O3 and SiO2 in the refractory bricks. The reaction also produces destructive volume expansion. The melting point of nepheline is only 1050°C. Under the working conditions of the incinerator, the temperature changes repeatedly, and the low-melting-point minerals melt and crystallize repeatedly, destroying the structure of the refractory materials.

[0005] In summary, the problem of hexavalent chromium formation in the residual bricks after the use of chromium-zirconium corundum bricks in the combustion area of ​​the incinerator is prominent under the condition of hazardous waste incineration. Chromium-free research should be carried out to develop modified corundum bricks with excellent high-temperature stability, corrosion resistance and wear resistance. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a modified corundum brick for key parts of a hazardous waste furnace incineration system and a preparation method thereof.

[0007] The modified corundum bricks used in the key parts of the hazardous waste furnace incineration system include, by mass fraction, 6% to 9% ZrO2 and 90% to 95% fused corundum components; wherein, the fused corundum components include 93% to 94% Al2O3, 0.1% to 0.2% SiO2 and 5% to 6.5% Na2O, wherein Al2O3 contains more than 99% β-Al2O3.

[0008] Preferably, ZrO2 is yttrium stabilized zirconia Y-SZ.

[0009] Preferably, in terms of mass fraction, it includes: 7% ZrO2 and 93% fused corundum components; wherein the fused corundum components include: 93.5% Al2O3, 0.2% SiO2 and 6.3% Na2O.

[0010] A method for preparing a modified corundum brick comprises the following steps:

[0011] Step 1, weighing a set mass of fused corundum component raw materials according to the mass fraction ratio of 93% to 94% of β-Al2O3, 0.1% to 0.2% of SiO2 and 5% to 6.5% of Na2O, and drying and sieving the raw materials to remove moisture and other impurities;

[0012] Step 2: Load the processed raw materials into an electric arc furnace, start the electric arc furnace and gradually heat it up to 2000°C to 2100°C, maintain it for a period of time, and stir the materials in the electric arc furnace during this process until the raw materials are completely melted and the gas therein is allowed to escape;

[0013] Step 3, pour the molten material into a mold, allow it to cool naturally and slowly solidify to obtain solidified fused corundum;

[0014] Step 4, annealing the solidified fused corundum: reheating the fused corundum to 1300° C. to 1400° C., and then slowly cooling it to room temperature to obtain annealed fused corundum;

[0015] Step 5, weighing a set mass of ZrO2 powder and annealed fused corundum according to the mass fraction ratio of 6% to 9% ZrO2 and 90% to 95% fused corundum; ball milling the ZrO2 powder and the annealed fused corundum with a ball mill, and mixing them evenly;

[0016] Step 6: Press the mixed powder into a green body of a set size by static pressing, and place the formed green body into a drying oven for drying at an appropriate temperature to remove moisture;

[0017] Step 7: sintering the green body.

[0018] Preferably, step 7 specifically comprises the following steps:

[0019] Step 7.1, preheating: slowly heat the dried green body to 550°C to 600°C, and keep it warm for a set time to remove residual moisture and other volatiles;

[0020] Step 7.2, sintering: continue to raise the temperature to 1700°C to 1800°C, and keep it at this temperature for a certain period of time to fully densify the material to obtain a sintered modified corundum brick;

[0021] Step 7.3, cooling: slowly cool the sintered modified corundum brick to room temperature to obtain modified corundum bricks, avoiding cracks caused by stress generated by rapid cooling.

[0022] The beneficial effects of the present invention are:

[0023] The present invention first uses β-Al2O3 as the main material to prepare fused corundum, then adds zirconium oxide as an additive to the fused corundum, and sinters the mixture of fused corundum and zirconium oxide. The obtained modified corundum brick has excellent thermal insulation performance, outstanding wear resistance, high temperature stability, thermal shock resistance and high mechanical strength; thermal shock resistance: due to the phase change toughening effect of zirconium oxide, the modified fused corundum exhibits better crack propagation resistance when undergoing rapid heating and cooling. Mechanical strength: after adding zirconium oxide, the overall mechanical strength of the material is improved, especially the fracture toughness is significantly improved.

[0024] The modified corundum bricks of the present invention can significantly extend the service life of the equipment. When applied to the key parts of the hazardous waste furnace incineration system, it can not only improve the operating efficiency and stability of the hazardous waste furnace incineration system, but also help reduce the leakage of harmful substances in the furnace and reduce the risk of operators being exposed to harmful environments. At the same time, it also reduces the probability of safety accidents such as fire and explosion in the furnace, and enhances the safety and environmental protection of the entire treatment process. DETAILED DESCRIPTION

[0025] The present invention is further described below in conjunction with embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for ordinary persons in the art, without departing from the principle of the present invention, the present invention can also be modified in some ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0026] Example 1

[0027] A modified corundum brick for key parts of a hazardous waste furnace incineration system comprises, by mass fraction, 7% ZrO2 and 93% fused corundum components; wherein the fused corundum components comprise 93.5% Al2O3, 0.2% SiO2 and 6.3% Na2O, wherein Al2O3 contains more than 99% β-Al2O3.

[0028] Example 2

[0029] Based on Example 1, a method for preparing a modified corundum brick comprises the following steps:

[0030] Step 1: Weigh a set mass of fused corundum component raw materials according to the ratio in Example 1, and dry and sieve the raw materials to remove moisture and other impurities;

[0031] Step 2: Load the processed raw materials into an electric arc furnace, start the electric arc furnace and gradually heat it up to 2050°C, maintain it for a period of time, and stir the materials in the electric arc furnace during this process until the raw materials are completely melted and the gas therein is allowed to escape;

[0032] Step 3, pour the molten material into a mold, allow it to cool naturally and slowly solidify to obtain solidified fused corundum;

[0033] Step 4, annealing the solidified fused corundum: reheating the fused corundum to 1300° C., and then slowly cooling it to room temperature to obtain annealed fused corundum;

[0034] Step 5, weighing a set mass of yttrium-stabilized zirconia Y-SZ powder and annealed fused corundum according to the ratio in Example 1; ball milling the yttrium-stabilized zirconia Y-SZ powder and the annealed fused corundum with a ball mill, and mixing them evenly;

[0035] Step 6: Press the mixed powder into a green body of a set size by static pressing, and place the formed green body into a drying oven for drying at an appropriate temperature to remove moisture;

[0036] Step 7, sintering the green body;

[0037] Step 7.1, preheating: slowly heat the dried green body to 550°C and keep it warm for a set time to remove residual moisture and other volatiles;

[0038] Step 7.2, sintering: continue to raise the temperature to 1750°C, and keep it at this temperature for a certain period of time to fully densify the material to obtain a sintered modified corundum brick;

[0039] Step 7.3, cooling: slowly cool the sintered modified corundum brick to room temperature to obtain modified corundum bricks, avoiding cracks caused by stress generated by rapid cooling.

Claims

1. A modified corundum brick for key parts of a hazardous waste furnace incineration system, characterized in that: In terms of mass fraction, it includes: 6% to 9% ZrO2 and 90% to 95% fused corundum components; wherein, the fused corundum components include 93% to 94% Al2O3, 0.1% to 0.2% SiO2 and 5% to 6.5% Na2O, wherein Al2O3 contains more than 99% β-Al2O3.

2. The modified corundum bricks for key parts of the hazardous waste incineration system according to claim 1 are characterized by: ZrO2 is yttrium stabilized zirconia Y-SZ.

3. The modified corundum bricks for key parts of the hazardous waste incineration system according to claim 1 are characterized in that: Calculated by mass fraction, it includes: 7% ZrO2 and 93% fused corundum components; wherein, the fused corundum components include: 93.5% Al2O3, 0.2% SiO2 and 6.3% Na2O.

4. A method for preparing the modified corundum brick according to claim 1, characterized in that: The steps include: Step 1, weighing a set mass of fused corundum component raw materials according to the mass fraction ratio of 93% to 94% of β-Al2O3, 0.1% to 0.2% of SiO2 and 5% to 6.5% of Na2O, and drying and sieving the raw materials; Step 2: Load the processed raw materials into an electric arc furnace, start the electric arc furnace and gradually heat it up to 2000°C to 2100°C, maintain it for a period of time, and stir the materials in the electric arc furnace during this process until the raw materials are completely melted; Step 3, pour the molten material into a mold, allow it to cool naturally and slowly solidify to obtain solidified fused corundum; Step 4, annealing the solidified fused corundum: reheating the fused corundum to 1300° C. to 1400° C., and then slowly cooling it to room temperature to obtain annealed fused corundum; Step 5, weighing a set mass of ZrO2 powder and annealed fused corundum according to the mass fraction ratio of 6% to 9% ZrO2 and 90% to 95% fused corundum; ball milling the ZrO2 powder and the annealed fused corundum with a ball mill, and mixing them evenly; Step 6: Press the mixed powder into a green body of a set size by static pressing, and place the formed green body into a drying oven for drying; Step 7: sintering the green body.

5. The method for preparing the modified corundum brick according to claim 4, characterized in that: Step 7 specifically includes the following steps: Step 7.1, preheating: slowly heat the dried green body to 550°C-600°C and keep it warm for a set time; Step 7.2, sintering: continue to raise the temperature to 1700°C-1800°C, maintain the temperature for a certain period of time, and obtain a sintered modified corundum brick; Step 7.3, cooling: slowly cool the sintered modified corundum brick to room temperature to obtain a modified corundum brick.