Refractory material for key part of medical waste incineration rotary kiln

Abstract

The invention belongs to the technical field of refractory materials, and mainly relates to a refractory material for key parts of a medical waste incineration rotary kiln. The refractory material for the key part of the medical waste incineration rotary kiln comprises the following raw materials in percentage by weight: 5%-20% of a composite binder, 10%-20% of 5-3mm corundum aggregate, 10%-15% of sintered corundum particles in which 3-1mm Al2O3 is greater than or equal to 99%, 5%-10% of 3-1mm chrome corundum aggregate, 15%-25% of 1-0mm chrome corundum aggregate, 20%-35% of alpha-Al2O3 micro powder, 3%-12% of industrial chromium oxide green and 0.1%-1.0% of a composite organic additive. By adding the composite binding agent, the prepared refractory material forms a part of liquid phase in a temperature interval when being used as a furnace lining, so that the density of the material is improved, the permeation of corrosive flue gas through pores is reduced, and the service life of a medical waste melting furnace is prolonged. The method has the remarkable advantages of excellent erosion resistance, safety and the like, is applied to the furnace bottom, the furnace waist and other parts of the medical waste incineration rotary kiln, and can realize the long service life of the furnace lining.

Description

Technical Field

[0001] The invention belongs to the technical field of refractory materials, and mainly relates to a refractory material for key parts of a medical waste incineration rotary kiln. Background Art

[0002] According to statistics, my country generates up to 140 million tons of medical waste every year. Since these medical wastes contain a large number of bacteria and other microorganisms, they are prone to secondary pollution and are absorbed by the human body, endangering human health. The "National List of Hazardous Wastes (2016 Edition)" issued in 2016 clearly stipulates that "infectious wastes", "injurious wastes" and "pathological wastes" are all hazardous wastes. The harmless treatment of medical waste has become an urgent problem that needs to be solved. Rotary kiln incineration can effectively reduce harmful substances and is the main way to harmlessly treat medical waste.

[0003] Medical waste has a complex composition, including materials of different properties such as rubber, plastic, glass, and metal, and it has the characteristics of high water content and strong chemical corrosion. The incineration of medical waste causes serious damage to the lining materials of the rotary kiln. At present, most of the commonly used lining materials of the incineration rotary kiln are refractory castables, which have many advantages such as low density, large porosity, low heat capacity, low thermal conductivity, and good thermal shock resistance. However, during the incineration of medical waste, due to the influence of factors such as high water content and strong corrosion, the lining will be severely eroded, which will cause The medical waste incineration rotary kiln has poor sealing, the furnace wall is prone to cracking and peeling, and the lining structure falls off, which leads to long equipment shutdown and maintenance cycles, seriously affecting the normal operation and service life of the equipment; due to the low temperature of medical waste incineration (900~1100℃), the high-purity Al2O3-Cr2O3 solid solution is difficult to melt to form a liquid phase at this temperature, resulting in large pores and poor density of the furnace lining refractory material. The highly volatile corrosive flue gas generated by incineration can easily penetrate into the furnace lining through the pores, causing the furnace lining to peel off and be damaged, and the furnace lining life is short. Summary of the invention

[0004] The purpose of the present invention is to propose a refractory material for key parts of a medical waste incineration rotary kiln, so that it can solve the practical problems of short refractory life and low working efficiency caused by severe erosion and spalling of the lining of the medical waste incineration rotary kiln by high-temperature slag. It has high temperature resistance, good corrosion resistance, low cost, and can meet the masonry requirements of the medical waste incineration rotary kiln.

[0005] The present invention adopts the following technical solutions to achieve the above-mentioned purpose: A refractory material for key parts of a medical waste incineration rotary kiln. The raw material composition and weight percentage of the refractory material are: 5%-20% of a composite binder, 10%-20% of a 5-3mm corundum aggregate, 10%-15% of 3-1mm sintered corundum particles with Al2O3≥99%, 5%-10% of 3-1mm chrome corundum aggregate, 15%-25% of 1-0mm chrome corundum aggregate, 20%-35% of α-Al2O3 micropowder, 3%-12% of industrial chromium oxide green, and 0.1%-1.0% of a composite organic admixture. The addition of the composite binder enables the prepared refractory material to form a partial liquid phase in the temperature range when used as a furnace lining, thereby improving the material density, reducing the penetration of corrosive flue gas through pores, and extending the life of the medical waste melting furnace.

[0006] The composite binder is composed of at least two of silica sol, magnesium chloride and magnesium sulfate; the composite binder and the Al2O3 and Cr2O3 components in the system generate a substance with a lower melting point than the Al2O3-Cr2O3 solid solution at high temperature, and will not cause the furnace lining to burn and collapse during use.

[0007] The corundum aggregate is one or more of brown corundum, white corundum and sintered corundum.

[0008] The chrome corundum aggregate is chrome corundum containing Cr2O3≥18%.

[0009] The composite organic admixture is composed of at least two of sulfite pulp waste liquid, cellulose and dextrin.

[0010] A preparation method of a refractory material for key parts of a medical waste incineration rotary kiln comprises the following steps: preparing materials according to the weight percentage, the first step, putting 20%-35% of α-Al2O3 micropowder and 3%-12% of industrial chromium oxide green in a ball mill to prepare a mixed powder; the second step, putting 10%-30% of corundum aggregate and 20%-35% of chrome corundum aggregate into a mixer for stirring, and after uniform stirring, adding the mixed powder, 5%-20% of a composite binder, and 0.1%-1.0wt% of a composite organic admixture in batches until the materials are uniform; the third step, putting the above materials into a mold, and using a press to press and form a blank, and after forming, placing it in a drying room to dry the moisture, the drying temperature is 100-150°C, and the drying time is 10-30h; the fourth step, high-temperature calcining the dried blank at 1500-1700°C for a holding time of 20-50h to obtain the refractory material for key parts of the medical waste incineration rotary kiln.

[0011] The ball milling medium of the mixed powder is made of corundum, and the ball milling time is 5 to 10 minutes.

[0012] The mixing time of the corundum aggregate and the chrome corundum aggregate in the mixer is 2 to 4 minutes.

[0013] The present invention provides a refractory material for key parts of a medical waste incineration rotary kiln, which has the following beneficial effects: first, the corrosion-resistant refractory material for key parts of a medical waste incineration rotary kiln of the present invention is used for key parts of the inner wall of the medical waste incineration rotary kiln, mainly the positions that are in direct contact with medical waste, such as the furnace bottom, furnace waist and other positions; before the medical waste enters the furnace, these places will be subjected to a short-term high-temperature shock, the temperature will rise sharply, and then will quickly drop, and so on and so forth; therefore, the basic performance requirement for selecting materials therein is resistance to thermal shock shock; secondly, the refractory material for key parts of the medical waste incineration rotary kiln of the present invention will also be corroded by harmful substances such as residual water vapor of medical waste, chlorides, sulfides, heavy metals, dioxins and the like in various medical waste flue gases, therefore, the second essential is corrosion resistance; and the present invention The raw materials and formula used just solve these two problems: corundum, chrome corundum and industrial chromium oxide will form aluminum-chromium solid solution at high temperature. The melting point of corundum is 2050℃. Since Cr2O3 and Al2O3 are both trigonal crystal systems, they can form a completely substitutional structure. In the Al2O3-Cr2O3 system, chromium oxide reacts with aluminum oxide to form a continuous solid solution under high temperature conditions. It has excellent high-temperature performance, high Mohs hardness, and excellent high-temperature wear resistance. Due to the relatively low Cr2O3 content, it can completely form an aluminum-chromium solid solution with Al2O3 to form a specific crystal structure, solidify the chromium ions, and largely inhibit the conversion of Cr3+ to Cr6+. Therefore, the chrome corundum formed is not easy to produce harmful substances Cr. 6+ , so it will not cause harm to the environment; the addition of composite binders such as silica sol, magnesium chloride, and magnesium sulfate makes the original Al2O3-Cr2O3 system contain a high-temperature liquid phase, which can effectively buffer thermal stress and improve thermal shock resistance.

[0014] Moreover, in the Al2O3-Cr2O3 system, as the Cr2O3 content increases, its high temperature creep resistance and slag erosion resistance increase significantly, and it has good thermal shock stability and chemical stability in high-aluminum refractory materials. In addition, the added industrial chromium oxide green has a certain diffusion bonding effect on the slag, can fill small pores, and play a certain protective role on the material surface.

[0015] In summary, the present invention has significant advantages such as excellent corrosion resistance and safety, and is applied to the bottom and waist of a medical waste incineration rotary kiln to extend the life of the furnace lining. DETAILED DESCRIPTION

[0016] The present invention is described in conjunction with the given embodiments, but does not constitute any limitation to the present invention. Embodiment 1:

[0017] A corrosion-resistant refractory material for key parts of a medical waste incineration rotary kiln, which is composed of the following components in weight percentage: 5wt% composite binder, 15wt% 5-3mm corundum aggregate, 12wt% 3-1mm corundum aggregate, 8wt% 3-1mm chrome corundum aggregate, 22wt% 1-0mm chrome corundum aggregate, 30wt% α-Al2O3 micropowder, 8wt% industrial chromium oxide green, and 0.5wt% composite organic admixture; wherein the composite binder is composed of 55% silica sol, 15% magnesium chloride, and 30% magnesium sulfate in weight percentage; the composite organic admixture is 0.2% sulfite pulp waste liquid, 0.1% cellulose, and 0.2% dextrin.

[0018] The steps of preparing the corrosion-resistant refractory material for the key parts of the medical waste incineration rotary kiln are as follows: (1) 30wt% of α-Al2O3 micropowder and 8wt% of industrial chromium oxide green are prepared in a ball mill to obtain a mixed powder; (2) 15wt% of 5-3mm corundum aggregate, 12wt% of 3-1mm corundum aggregate, 8wt% of 3-1mm chrome corundum aggregate, and 22wt% of 1-0mm chrome corundum aggregate are placed in a mixer for stirring, and after uniform stirring, the mixed powder, 5wt% of a composite binder, and 0.5wt% of a composite organic admixture are added in batches until the material is uniform; (3) the above materials are placed in a mold, and are pressed and formed by a press machine. After the forming is completed, they are placed in a drying room at 120°C for drying until the moisture content is less than 0.5%; (4) the dried corrosion-resistant refractory material prepared by the present invention is placed at a high temperature of 1600°C for sintering for 24 hours to obtain the desired product.

[0019] The performance index of the product obtained by the above steps is: volume density 3.12g / cm 3 , apparent porosity 16.5%, 1400℃×0.5h high temperature flexural strength 14.6MPa, static slag erosion depth 2.1mm. Embodiment 2:

[0020] A corrosion-resistant refractory material for key parts of a medical waste incineration rotary kiln, which is composed of the following components by weight percentage: 8wt% composite binder, 13wt% 5-3mm corundum aggregate, 13wt% 3-1mm corundum aggregate, 8wt% 3-1mm chrome corundum aggregate, 20wt% 1-0mm chrome corundum aggregate, 32wt% α-Al2O3 micropowder, 6wt% industrial chromium oxide green, and 0.8wt% composite organic admixture. The composite binder is composed of 55% silica sol, 15% magnesium chloride, and 30% magnesium sulfate by weight. The composite organic admixture is 0.2% sulfite pulp waste liquid, 0.1% cellulose, and 0.2% dextrin.

[0021] The steps of preparing the corrosion-resistant refractory material for the key parts of the medical waste incineration rotary kiln are as follows: (1) 32wt% of α-Al2O3 micropowder and 6wt% of industrial chromium oxide green are prepared in a ball mill to obtain a mixed powder; (2) 13wt% of 5-3mm corundum aggregate, 13wt% of 3-1mm corundum aggregate, 8wt% of 3-1mm chrome corundum aggregate, and 20wt% of 1-0mm chrome corundum aggregate are placed in a mixer for stirring, and after uniform stirring, the mixed powder, 8wt% of composite binder, and 0.8wt% of composite organic admixture are added in batches until the material is uniform; (3) the above materials are placed in a mold, and are pressed and formed by a press machine. After the forming is completed, they are placed in a drying room at 110°C for drying until the moisture content is less than 0.5%; (4) the dried corrosion-resistant refractory material prepared by the present invention is placed at a high temperature of 1650°C for sintering for 30 hours to obtain the desired product.

[0022] The performance index of the product obtained by the above steps is: volume density 3.15g / cm 3 , apparent porosity 15.9%, 1400℃×0.5h high temperature flexural strength 14.8MPa, static slag erosion depth 2.0mm. Embodiment 3:

[0023] A corrosion-resistant refractory material for key parts of a medical waste incineration rotary kiln, which is composed of the following components by weight percentage: 15wt% composite binder, 20wt% 5-3mm corundum aggregate, 10wt% 3-1mm corundum aggregate, 5wt% 3-1mm chrome corundum aggregate, 20wt% 1-0mm chrome corundum aggregate, 25wt% α-Al2O3 micropowder, 5wt% industrial chromium oxide green, and 0.6wt% composite organic admixture; wherein the composite binder is composed of 40% silica sol, 20% magnesium chloride, and 40% magnesium sulfate by weight percentage. The composite organic admixture is 0.2% sulfite pulp waste liquid, 0.2% cellulose, and 0.2% dextrin.

[0024] The steps of the preparation method of the corrosion-resistant refractory material for the key parts of the medical waste incineration rotary kiln are as follows: (1) 25wt% of α-Al2O3 micropowder and 5wt% of industrial chromium oxide green are prepared in a ball mill to obtain a mixed powder; (2) 20wt% of 5-3mm corundum aggregate, 10wt% of 3-1mm corundum aggregate, 5wt% of 3-1mm chrome corundum aggregate, and 20wt% of 1-0mm chrome corundum aggregate are placed in a mixer for stirring, and after uniform stirring, the mixed powder, 15wt% of a composite binder, and 0.6wt% of a composite organic admixture are added in batches until the material is uniform; (3) the above materials are placed in a mold, and are pressed and formed by a press machine. After the forming is completed, they are placed in a drying room at 120°C for drying until the moisture content is less than 0.5%; (4) the dried corrosion-resistant refractory material prepared by the present invention is placed at a high temperature of 1650°C for sintering for 24 hours to obtain the desired product.

[0025] The product performance index obtained by the above steps is: volume density 3.10g / cm 3 , apparent porosity 17.5%, 1400℃×0.5h high temperature flexural strength 14.2MPa, static slag erosion depth 2.5mm.

Claims

1. A refractory material for key parts of a medical waste incineration rotary kiln, characterized in that: The raw material composition and weight percentage of the refractory material are: 5%-20% of composite binder, 10%-20% of 5-3mm corundum aggregate, 10%-15% of 3-1mm Al2O3≥99% sintered corundum particles, 5%-10% of 3-1mm chrome corundum aggregate, 15%-25% of 1-0mm chrome corundum aggregate, 20%-35% of α-Al2O3 micropowder, 3%-12% of industrial chromium oxide green, and 0.1%-1.0% of composite organic admixture. The addition of the composite binder allows the prepared refractory material to form a partial liquid phase in the temperature range when used as a furnace lining, thereby improving the material density, reducing the penetration of corrosive flue gas through pores, and extending the life of the medical waste melting furnace.

2. The refractory material for key parts of a medical waste incineration rotary kiln according to claim 1, characterized in that: The composite binder is composed of at least two of silica sol, magnesium chloride and magnesium sulfate; the composite binder and the Al2O3 and Cr2O3 components in the system generate a substance with a lower melting point than the Al2O3-Cr2O3 solid solution at high temperature, and will not cause the furnace lining to burn and collapse during use.

3. The refractory material for key parts of a medical waste incineration rotary kiln according to claim 1, characterized in that: The chrome corundum aggregate is chrome corundum containing Cr2O3≥18%.

4. The corrosion-resistant refractory material for key parts of a medical waste incineration rotary kiln according to claim 1, characterized in that: The composite organic admixture is composed of at least two of sulfite pulp waste liquid, cellulose and dextrin.