High-toughness impact-resistant special corundum product and preparation method thereof
Through the electric smelting and static cooling process in a large-scale tilting furnace, high-toughness large-sized corundum blocks are prepared, which solves the problem that ordinary corundum blocks are easily corroded in high-temperature environments and realizes the high-efficiency and low-energy consumption production of high-performance corundum products.
Patent Information
- Application Number
- CN202510953028.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-10
- Publication Date
- 2025-10-14
AI Technical Summary
Existing ordinary corundum blocks are easily corroded in high-temperature environments, and lack toughness and thermal shock resistance, which limits their application under special working conditions. In addition, the traditional smelting process is inefficient, energy-intensive, and the product density is poor.
High-grade smelted bauxite mixture is electro-smelted in a large dumping furnace. By controlling the electrode power and temperature gradient, high-temperature melting and refining are achieved. The mixture is then allowed to cool and form to produce high-toughness large-sized corundum blocks.
The produced corundum blocks have high toughness and strong impact resistance, low apparent porosity, high bulk density, and excellent thermal shock resistance. They are suitable for high temperature environments, reduce the crushing and screening links, and increase the added value of the products.
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of refractory materials, and relates to production of corundum products, in particular to a high-toughness impact-resistant special corundum product and a preparation method thereof. BACKGROUND
[0002] At present, common corundum blocks applied in the field of refractory wear-resistant materials cannot meet the use requirements of special working conditions in terms of toughness and thermal shock resistance, and are usually broken into particles from 250mm block corundum and added with auxiliary materials to be used as castables or shaped bricks. In some fields with high requirements for the density and toughness of refractory materials, such as iron channel molten liquid ports, casting will form small pores to cause the disadvantage of poor density.
[0003] In addition, the 5000KVA transformer used in the electric smelting furnace of the common fused corundum block has a feeding amount of 16-19T per furnace, and the smelting time is controlled within 6-9 hours. Although a certain amount of corundum blocks can be obtained, the density of the core of the corundum block is poor.
[0004] The traditional smelting and cooling method of corundum is to pour the corundum melt into a ladle and stand for 48 hours before water cooling. The crystal morphology of the corundum block is not ideal, and the toughness, thermal shock resistance, high temperature resistance and impact resistance are poor after water cooling. The corundum block is mainly applied in blast furnace castables, and is prone to cause problems such as early erosion and shutdown for maintenance in the environment of high temperature and high erosion frequency of special steel smelting.
[0005] The traditional corundum block is applied in the refractory material industry, and can be sorted into corundum blocks with a size of less than 25cm, and then broken and sieved into 0-12mm section sand of different models. In the refractory material industry, the section sand needs to be proportioned and cast into a shape, and has the disadvantages of multiple processing procedures and poor casting density. SUMMARY
[0006] The application overcomes the shortcomings of the prior art, and provides a high-toughness impact-resistant special corundum product and a preparation method thereof, so as to improve the toughness and impact resistance of the corundum product. The application is realized through the following technical scheme: A preparation method of a high-toughness impact-resistant special corundum product, comprising the following steps: S1, raw material pretreatment: using bauxite of 84 or above or mixing bauxite of 85 with bauxite of 82 in a mass ratio of 7:3~8:2, and forming bauxite mixture after breaking and sieving; S2, smelting S2.1, arc starting stage: laying arc starting coke in the pouring furnace to form a current path, and starting the electrode to cause an electric arc after power-on, and then adding a part of the mixture after the current rises to normal load; S2.2, smelting stage: the temperature is between 2050~2100℃, the bauxite mixture is melted into liquid state to carry out reduction reaction, the remaining bauxite mixture is continuously added in the reaction process to keep the thickness of the material layer in the furnace, and the bauxite mixture is completely melted; S2.3, refining stage: the temperature of the molten liquid is increased to 2300~2500℃; The smelting stage and the refining stage are 7~8 hours in total; S3, cooling and forming After the smelting is completed, the molten liquid in the furnace is poured into a special ladle, the ladle is placed on the furnace bottom for 2~3 hours, and then is dragged into a cooling field for standing and cooling, and the cooling time is 50~60 hours.
[0007] Preferably, in step S1, the particle size of the bauxite mixture obtained after crushing and screening is 20-50mm.
[0008] Preferably, the size of the furnace cylinder of the pouring furnace is 500~600cm in diameter and 300~400cm in depth, and brown corundum refractory material is used for knotting in the furnace.
[0009] Preferably, the thickness of the furnace lining of the pouring furnace is 75~85cm, and the thickness of the lining of the furnace bottom is 150~200cm.
[0010] Preferably, a graphitized three-phase electrode is used in the pouring furnace, and the power of the graphitized three-phase electrode is ≥5000KVA.
[0011] Preferably, the mixture is directly added to the middle of the graphitized three-phase electrode for smelting.
[0012] Preferably, the bauxite mixture is added into the pouring furnace in three batches according to the melting condition in the furnace and the display size of current and voltage.
[0013] Preferably, the ladle turning time is determined according to the surface temperature of the ladle during cooling, the ladle turning processing is carried out after the standing and cooling is completed, and whether the water cooling is carried out is determined by measuring the temperature of each part of the prepared corundum block.
[0014] The corundum product prepared by the preparation method of the high-toughness impact-resistant special corundum product.
[0015] The beneficial effects of the present application relative to the prior art are: 1. The present application can provide a new product of corundum block with high toughness, large size, generally divided into maximum diameter 25cm, 40cm, 50cm, 60cm, 70cm, uniform crystal structure and dense structure; through detection, the high-toughness corundum block product has low impurity content, high thermal shock resistance, refractoriness of 1800℃+, apparent porosity of ≤4%, and bulk density of ≥3.95g / cm 3, phase analysis high-toughness corundum block corundum phase accounts for 95%, the overall content is more stable than the traditional corundum block phase, mainly reflected in the new high-toughness corundum block's thermal shock resistance and the advantages of large dense crystalline proportion, solve the ordinary corundum block due to low toughness, small size after crushing, low hardness and poor density, poor thermal shock resistance. The corundum product prepared by the present application has the characteristics of uniform and dense crystallization, excellent thermal shock stability, high softening point under load, small high temperature creep value, good chemical corrosion resistance and the like, and can be directly applied to special fields.
[0016] 2, the production equipment of high-toughness corundum block realizes mass production, which is applied to the smelting of the current large-scale dumping smelting furnace, and is matched with special smelting process and cooling mode, so that the equipment application and production process are changed, the high-toughness corundum block production equipment is improved, and the safe and environmentally-friendly operation is realized, and the labor intensity of personnel is reduced.
[0017] 3, reduce the crushing and screening link, and the corundum block can be directly applied to special industries to improve the product added value. DETAILED DESCRIPTION
[0018] In order to make the technical problems, technical schemes and beneficial effects to be solved by the present application more clear and obvious, the present application is further described in detail in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application. The technical scheme of the present application is described in detail below in combination with embodiments, but the protection scope is not limited thereto. EMBODIMENT
[0019] The embodiment provides a high-toughness impact-resistant special corundum product and a preparation method thereof, and the preparation method comprises the following steps: S1, raw material pretreatment: 85-grade bauxite and 82-grade bauxite are mixed in a mass ratio of 7:3, and after crushing and screening, a mixture is formed; the total amount of the mixture is 16 tons, and the particle size of the mixture obtained after crushing and screening is 20-50 mm.
[0020] S2, smelting The 5000KVA large-scale dumping furnace is used for electric smelting high-density corundum block; the size of the furnace is 550cm in diameter and 350cm in depth, the brown corundum refractory material is used for knotting in the furnace (the thickness of the furnace lining is 80cm, and the thickness of the furnace bottom lining is 180cm), which can better ensure that the heat in the furnace is not lost and the energy waste is reduced, the 505mm graphitized high-power electrode is used for the three-phase electrode, and the power of the graphitized three-phase electrode is 5000KVA. The graphitized three-phase electrode is vertically inserted into the furnace, which can effectively reduce the resistivity and improve the useful work; in order to make the smelting sufficient, the single-furnace feeding amount is controlled to be 10-15 tons, and the feeding amount is adjusted in the single-furnace yield to achieve the best smelting amount to improve the density.
[0021] S2.1, Arc starting stage: Before arcing, the graphitized three-phase electrode circle is adjusted to about 150cm, and a layer of iron filings and arcing coke powder is spread between the graphitized three-phase electrodes to facilitate the connection of the graphitized three-phase electrodes to form a current path for arcing. After power is turned on, the electrodes fall to trigger an arc. After the current rises to normal load, 50% of the slaked alumina mixture is added; the mixture is directly added to the middle of the graphitized three-phase electrodes for smelting.
[0022] S2.2 Melting Stage: The temperature is 2100°C. The mixture is melted into liquid and a reduction reaction is carried out. 30% of the mixture is added first. After it melts, the remaining 20% is added. During the reaction, the mixture is added in batches to maintain the thickness of the material layer in the furnace and to ensure that all the mixture is melted. The smelting power is delivered at 5000kw / h, and high voltage is used from beginning to end to melt the charge (low current is not used, and the voltage should not be reduced. Keeping the power at level 13 can gradually increase the power), thereby increasing the furnace temperature, reducing the viscosity of the bottom melt, and ensuring a steady increase in the furnace temperature.
[0023] S2.3 Refining Stage: Raise the melt temperature to 2500°C for refining; this further ensures the proper formation and distribution of the high-toughness corundum phase within the furnace, while also ensuring smooth release of gases within the furnace to avoid furnace reactions. Refining must be thorough, with no unmelted alumina remaining on the furnace sides or lid. Ensure the temperature is elevated. After sufficient refining, inspect the dipstick to ensure the top and bottom surfaces are smooth and consistent, with consistent thickness. (If the thickness is inconsistent, with the bottom portion being significantly thicker than the top, this indicates insufficient temperature.) Pour the product only after it shows signs of cracking.
[0024] The smelting and refining stages lasted a total of 5.5 hours; S3, cooling molding After the smelting is completed, the power is turned off and the heating is stopped. The graphitized three-phase electrode is taken out and the molten liquid in the furnace is poured into two high-connecting bags respectively to avoid mixing and causing non-separation and iron beans. The surface of the high-connecting silica bricks should be treated with graphite powder coating. After each pouring, the high-connecting bag is left to stand at the bottom of the furnace for 2 hours, and then dragged into the cooling yard for cooling. The cooling time is 50 hours. The cooling time is generally determined according to the season. During cooling, the temperature of the outer wall of the bag should be paid attention to to avoid cooling too quickly. After reaching the process cooling time, the bag is turned over and the temperature of each part of the high-toughness corundum block is measured to decide whether to water cool it.
[0025] In this embodiment, the single furnace feeding amount is controlled at 10-15 tons, and the furnace feeding amount of the mixed material in the early, middle and late stages is adjusted and controlled, and the feeding amount is gradually reduced. This scheme requires that the corundum block is in a large size form and has high toughness, and the phase composition analysis shows that the high-density corundum block phase accounts for more than 85%, and the corundum phase accounts for 95%. The specific reason is that the large-scale tilting furnace uses a graphitized high-power electrode, and in the smelting process, the electrode has good conductivity, and is matched with a 5000KVA high-power distribution. From the arc striking-smelting-refining-tapping, each link is more efficient than the traditional process, and the highest temperature at the center of the three-phase electrode can reach more than 2300 degrees (the traditional corundum block smelting temperature is 2100 degrees). The effective high-temperature environment provides favorable conditions for the formation and growth of the corundum phase. Therefore, the high-toughness corundum block produced by the new process has higher purity, and the new high-toughness corundum block has the advantages of large size, high toughness, and can be directly applied, reducing the crushing and screening link. The disadvantages of the traditional corundum block, such as poor density difference, poor thermal shock resistance, low toughness and easy cracking, are solved. It has the characteristics of excellent thermal shock stability, small high-temperature creep value, good chemical corrosion resistance, etc. At present, it has been normally produced and applied to test, and the application comprehensive evaluation has reached the expected requirements.
[0026] The high-toughness impact-resistant special corundum product prepared by the above preparation method has low impurity content, high thermal shock resistance, and a refractoriness of 1800℃+, an apparent porosity of ≤4%, and a bulk density of ≥3.95g / cm 3 The phase analysis of the high-toughness corundum block shows that the corundum phase accounts for 95%, which is more stable and superior than the traditional corundum block phase. The advantages of the new high-toughness corundum block are mainly reflected in its thermal shock resistance and large proportion of dense crystals. The disadvantages of the ordinary corundum block, such as small size, low hardness and density, and poor thermal shock resistance after crushing and screening, are solved. It has the characteristics of uniform and dense crystal, excellent thermal shock stability, high load softening point, small high-temperature creep value, good chemical corrosion resistance, etc. and can be directly applied to special fields. Embodiment
[0027] The embodiment proposes a high-toughness impact-resistant special corundum product and a preparation method thereof. The preparation method comprises the following steps: S1, raw material pretreatment: 85-grade bauxite and 82-grade bauxite are mixed in a mass ratio of 8:2, and after crushing and screening, a mixed material is formed; the total amount of the mixed material is 10 tons, and the particle size of the mixed material after crushing and screening is 20-40mm.
[0028] S2, smelting A large 5000KVA dumping furnace is used to melt high-density corundum blocks. The furnace has a diameter of 500cm and a depth of 300cm. Brown corundum refractory materials are used for the furnace (the furnace lining is 75cm thick and the furnace bottom lining is 150cm thick). This ensures that heat is not lost in the furnace and reduces energy waste. The three-phase electrodes use 505mm graphitized high-power electrodes with a power of 5000KVA. Inserting the graphitized three-phase electrodes vertically into the furnace effectively reduces resistivity and increases useful work. To ensure sufficient smelting, the single furnace feed rate is controlled at 10-15 tons. The single furnace output is adjusted by adjusting the feed rate to achieve the optimal smelting volume and improve density.
[0029] S2.1, Arc starting stage: Before arcing, the graphitized three-phase electrode circle is adjusted to about 150cm, and a layer of iron filings and arc starting coke powder is spread between the graphitized three-phase electrodes to facilitate the connection of the graphitized three-phase electrodes to form a current path for arcing. After power is turned on, the electrodes fall to trigger an arc. After the current rises to normal load, 55% of the mixture is added; the mixture is directly added to the middle of the graphitized three-phase electrodes for smelting.
[0030] S2.2 Melting Stage: The temperature is 2050°C. The mixture is melted into liquid and a reduction reaction is carried out. 30% of the mixture is added first. After it melts, the remaining 15% is added. During the reaction, the mixture is added in batches to maintain the thickness of the material layer in the furnace and to ensure that all the mixture is melted. The smelting power is delivered at 5000kw / h, and high voltage is used from beginning to end to melt the charge (low current is not used, and the voltage should not be reduced. Keeping the power at level 13 can gradually increase the power), thereby increasing the furnace temperature, reducing the viscosity of the bottom melt, and ensuring a steady increase in the furnace temperature.
[0031] S2.3 Refining Stage: Raise the melt temperature to 2400°C for refining; this further ensures the proper formation and distribution of the high-toughness corundum phase within the furnace, while also ensuring smooth release of gases within the furnace to avoid furnace reactions. Refining must be thorough, with no unmelted alumina remaining on the furnace sides or lid. Ensure the temperature is elevated. After sufficient refining, inspect the dipstick to ensure the top and bottom surfaces are smooth and consistent, with consistent thickness. (If the thickness is inconsistent, with the bottom portion being significantly thicker than the top, this indicates insufficient temperature.) Only pour the product if good cracks are present.
[0032] The smelting and refining stages lasted a total of 6 hours; S3, cooling molding After smelting, stop heating by cutting off power, take out the graphitized three-phase electrode, pour the molten liquid in the furnace into two high-connection ladles respectively to avoid mixing and causing non-separation and iron bean phenomenon, and the surface of the silica brick of the high-connection ladle should be treated with graphite powder coating. After each pouring is completed, the high-connection ladle is placed on the bottom of the furnace for 2.5 hours, and then dragged into the cooling field for standing and cooling, and the cooling time is 60 hours. Generally, the cooling time is determined according to the season, and the temperature of the outer wall of the ladle should be paid attention to at all times to avoid rapid cooling. After the process cooling time is reached, the ladle is turned over, and the temperature of each part of the high-toughness corundum block is measured to determine whether to pour water for cooling. Embodiment
[0033] The embodiment provides a high-toughness impact-resistant special corundum product and a preparation method thereof, and the preparation method comprises the following steps: S1, raw material pretreatment: 85-grade bauxite and 82-grade bauxite are mixed in a mass ratio of 7.5:2.5, and after crushing and screening, a mixed material is formed; the total amount of the mixed material is 15 tons, and the particle size of the mixed material obtained after crushing and screening is 30-50 mm.
[0034] S2, smelting A 5000KVA large-scale pouring furnace is used to electrically melt high-density corundum blocks; the size of the furnace is 600cm in diameter and 400cm in depth, brown corundum refractory material is used for knotting in the furnace (the thickness of the furnace lining is 85cm, and the thickness of the inner lining of the furnace bottom is 200cm), which can better ensure that the heat in the furnace is not lost and reduce energy waste; a 505mm graphitized high-power electrode is used for the three-phase electrode, and the power of the graphitized three-phase electrode is 5000KVA. The graphitized three-phase electrode is vertically inserted into the furnace, which can effectively reduce the resistivity and improve the useful work; in order to make the smelting sufficient, the single-furnace feeding amount is controlled at 10-15 tons, and the feeding amount is adjusted to achieve the best smelting amount and improve the density in terms of single-furnace output.
[0035] S2.1, arc striking stage: Before arc striking, the graphitized three-phase electrode is adjusted to about 150cm, and a layer of iron filings and arc striking coke powder is laid between the graphitized three-phase electrodes to facilitate the connection of the graphitized three-phase electrodes to form a current path. After power is turned on, the electrode falls to initiate an electric arc, and after the current rises to normal load, 45% of the mixed material is added; the mixed material is directly added to the middle of the graphitized three-phase electrode for smelting.
[0036] S2.2, smelting stage: the temperature is 2100℃, the mixed material is melted into a liquid state for reduction reaction, 35% of the mixed material is first added, after melting, the remaining 20% of the mixed material is added, and the mixed material is added in batches during the reaction process to maintain the thickness of the material layer in the furnace and can make the mixed material completely melted; The power of smelting is 5000kw / h, high voltage is used to melt the furnace charge from beginning to end (without low current, without reducing voltage, keeping 13 gears to gradually increase power), so as to improve the furnace temperature, reduce the bottom molten liquid viscosity phenomenon, and ensure the steady improvement of the furnace temperature.
[0037] S2.3, refining stage: the molten liquid temperature is increased to 2500 DEG C for refining, so as to further ensure the reasonable generation and distribution of high toughness corundum phase in the furnace, and ensure the smooth release of gas in the furnace, and avoid causing the furnace condition reaction. The refining should be sufficient, there should be no unmelting bauxite on the edge of the furnace and the cover, so as to ensure the temperature rise, and the refining is sufficient to observe the stick, the upper and lower surfaces of the stick are smooth and consistent, the thickness is consistent (if the upper and lower thicknesses are inconsistent, and the lower part of the stick is obviously thicker than the upper part, it means that the lower temperature is not enough), and the good crack can be poured.
[0038] The smelting stage and the refining stage are performed for 5.5 hours; S3, cooling and forming After the smelting is finished, the power is cut off to stop heating, the graphitized three-phase electrode is taken out, the molten liquid in the furnace is poured into two high connection packages respectively, so as to avoid mixing to cause non-separation and iron bean phenomenon, the surface of the high connection package silicon brick should be treated with graphite powder coating. After each pouring is finished, the high connection package is placed on the furnace bottom for 2.5h, and then is dragged into the cooling field for standing and cooling, the cooling time is 60 hours, generally the cooling time is determined according to the season, the cooling should be paid attention to the temperature of the outer wall of the package at all times, so as to avoid too fast cooling, after the process cooling time is reached, the package is turned over, and the temperature of each part of the high toughness corundum block is measured to determine whether water cooling is needed.
[0039] The above is the further detailed description of the application combined with the preferred embodiments, which cannot be regarded as the limitation of the specific embodiments of the application, for the ordinary skilled in the art to which the application belongs, without departing from the application, a number of simple deductions or substitutions can be made, which should be regarded as belonging to the application, and the patent protection scope is determined by the submitted claims.
Claims
1. A method for preparing a high-toughness and impact-resistant special corundum product, characterized in that: The following steps are involved: S1. Raw material pretreatment: Use 84-grade or higher grade smelted bauxite or mix 85-grade or higher grade bauxite with 82-grade bauxite in a mass ratio of 7:3-8:2, crush and screen to form a smelted bauxite mixture; S2. Melting S2.1, Arcing stage: Arcing coke is laid in the dumping furnace to form a current path. After power is applied, the electrode falls to trigger an arc. After the current rises to normal load, a portion of the smelted bauxite mixture is added; S2.2, Melting Stage: The temperature is between 2050-2100°C, and the mixture is melted into liquid for reduction reaction. During the reaction, the remaining smelted bauxite mixture is continuously added to maintain the thickness of the material layer in the furnace and to melt the smelted bauxite mixture completely; S2.3, refining stage: raising the melt temperature to between 2300 and 2500°C; The smelting and refining stages take 7 to 8 hours in total; S3, cooling molding After smelting, pour the molten metal in the furnace into a special ladle. After the ladle is left at the bottom of the furnace for 2 to 3 hours, it is dragged into the cooling yard and left to cool for 50 to 60 hours.
2. The method for preparing a high-toughness and impact-resistant special corundum product according to claim 1, characterized in that: In step S1, the particle size of the slaked bauxite mixture obtained after crushing and screening is 20-50 mm.
3. The method for preparing a high-toughness and impact-resistant special corundum product according to claim 1, characterized in that: The furnace size of the dumping furnace is 500-600cm in diameter and 300-400cm in depth, and brown corundum refractory material is used for knotting in the furnace.
4. The method for preparing a high-toughness and impact-resistant special corundum product according to claim 3, characterized in that: The lining thickness of the dumping furnace is 75~85cm, and the lining thickness of the furnace bottom is 150~200cm.
5. The method for preparing a high-toughness and impact-resistant special corundum product according to claim 4, characterized in that: Graphitized three-phase electrodes are used in the dumping furnace, and the power of the graphitized three-phase electrodes is ≥5000KVA.
6. The method for preparing a high-toughness and impact-resistant special corundum product according to claim 5, characterized in that: The smelted bauxite mixture is directly added into the middle of the graphitized three-phase electrode for smelting.
7. The method for preparing a high-toughness and impact-resistant special corundum product according to claim 1, characterized in that: According to the melting situation in the furnace and the current and voltage displayed, the slaked bauxite mixture is added into the dumping furnace in three batches.
8. The method for preparing a high-toughness and impact-resistant special corundum product according to claim 1, characterized in that: During cooling, the time for turning the package is determined according to the surface temperature of the package. After the static cooling is completed, the package is turned over, and the temperature of each part of the prepared corundum block is measured to determine whether water cooling should be performed and the amount of water to be poured.
9. A corundum product prepared by the method for preparing a high-toughness and impact-resistant special corundum product according to any one of claims 1 to 8.