Magnesium aluminate spinel smelted by utilizing electric furnace fly ash and preparation method of magnesium aluminate spinel

Abstract

The invention discloses magnesium aluminate spinel smelted by utilizing electric furnace fly ash and a preparation method of the magnesium aluminate spinel. Raw materials comprise industrial alumina powder, magnesium oxide powder, fly ash and an additional binding agent; according to the method, few raw materials are used, the technological process is relatively simple, the electric furnace fly ash serves as an ingredient to be formed and prefabricated into a green brick, the green brick is crushed and added into an electric arc furnace, stability of MgO and Al2O3 raw material components in the green brick is guaranteed, the defects that dust pollution is caused and SO2 and nitric oxide exceed the standard due to the fact that the fly ash is directly added into the electric arc furnace are overcome, and pollution to the environment is reduced; and the magnesium aluminate spinel raw material with more excellent performance can be produced, the electric furnace fly ash is consumed and recycled in batches, and the green development of the electric furnace smelting process is facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of composite refractory material production, and particularly relates to a magnesia-alumina spinel smelted by utilizing electric furnace dust removal ash and a preparation method thereof. Background Art

[0002] As is known, magnesium-aluminum spinel is composed of MgO and Al 2 O 3 The composite mineral has the advantages of high melting point, high strength, low thermal expansion rate, and corrosion resistance. It is a refractory material with excellent properties. At present, there are two methods for synthesizing magnesium-aluminum spinel, namely, electric melting method and sintering method. As one of the basic methods for synthesizing magnesium-aluminum spinel raw materials, the electric melting method has the characteristics of simple process, high volume density of synthesized magnesium-aluminum spinel, stable chemical composition, and large crystallization compared with the sintering method.

[0003] The electric melting method uses the discharge of electrodes in a three-phase electric arc furnace to melt raw materials such as alumina and magnesium oxide powder into liquid, which becomes solid magnesium-aluminum spinel after cooling and crystallization. Since most of the raw materials are powder particles, they are easy to spread and produce dust pollution during the melting and liquefaction process, so a dust removal device is installed inside the electric furnace to collect dust. Studies have shown that the main component of electric furnace dust removal ash is 40-50wt% Al 2 O 3 , 45-50wt% MgO and a small amount of other impurities. In the normal production process, the dust collected by the dust removal device will be added back to the electric furnace for smelting in small batches. Compared with the raw materials, the dust is lighter in texture and tends to float on the surface of the melt during the smelting process, making it difficult to melt. As a result, the smelted magnesium-aluminum spinel has low purity and poor appearance, affecting product quality.

[0004] Therefore, how to recycle electric furnace dust without affecting the quality of magnesia-alumina spinel products and how to improve the recycling rate of electric furnace dust have become problems that technicians in this field need to solve urgently. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a magnesium-aluminum spinel smelted by using electric furnace dust removal ash and a preparation method thereof, which uses less raw materials and has a relatively simple process flow. The electric furnace dust removal ash is used as a batching material to form a prefabricated brick, and the brick is crushed and added to the electric arc furnace, which ensures that MgO and Al in the brick are 2 O 3 The stability of raw material composition avoids dust pollution and SO 2 , excessive nitrogen oxides and other disadvantages, reduce environmental pollution, and produce magnesium-aluminum spinel raw materials with better performance. The batch consumption and repeated utilization of electric furnace dust removal ash is conducive to the green development of electric furnace smelting technology.

[0006] The technical solution adopted by the present invention is: a magnesium-aluminum spinel smelted using electric furnace dust ash, comprising the following raw material components and added weight portions: 68 to 75 parts of industrial alumina powder with a particle size of ≤0.15 mm, 20 to 28 parts of magnesium oxide powder with a particle size of ≤0.075 mm, 2 to 5 parts of dust ash with a particle size of ≤0.063 mm, and 1 to 3 parts of an additional binder.

[0007] The industrial alumina powder is calcined alumina powder.

[0008] The magnesium oxide powder is 90-95wt% of light-burned magnesium powder, dead-burned magnesium powder or a combination of the two.

[0009] The binder is one or more combinations of aluminum phosphate, hydroxymethyl cellulose, pulp waste liquid, and yellow dextrin.

[0010] A method for preparing spinel by smelting electric furnace dust ash comprises the following steps: Step 1: Ingredients: weigh the raw materials in proportion according to the formula requirements for smelting magnesia-alumina spinel; Step 2: Premixing: Add the weighed industrial alumina powder, magnesium oxide powder and dust removal ash into the vertical double cone sand mixer for premixing for 15 minutes. After mixing, store in a packaging bag and seal it for later use. Step 3: Mixing: Mix the raw materials of magnesium aluminum spinel, pour the pre-mixed raw materials into a strong sand mixer, mix and stir for 3 to 5 minutes, evenly add the binder after mixing, and continue to mix and stir for 10 to 15 minutes until the raw materials are evenly dispersed and mixed into a mud material for standby use; Step 4: Add materials: Use a feeder to evenly add the clay into the molding silo, and keep the clay evenly dispersed during the adding process; Step 5: Molding: Use a 300t hydraulic press to press the mud in the silo into bricks of 280mm×100mm×100mm size; Step 6: Drying: The formed bricks are stacked on the kiln car as a whole and dried in a tunnel kiln at a temperature of 100-150°C for 36-48 hours. Step 7: Crushing: Put the fully dried bricks into a jaw crusher or a vertical crusher for crushing. The crushed bricks are transported by a bucket elevator to a designated silo for standby use. Step 8. Smelting: The capacity of the three-phase electric arc furnace transformer used is 3600KVA, the smelting voltage is 160V, and the normal operating current is 4000-6000A. Before the start of smelting, lay 200mm thick broken brick raw materials on the bottom of the furnace. After the bottom layer of raw materials is melted, add the broken brick raw materials in the silo into the electric arc furnace in small amounts and multiple times to ensure that the raw materials are fully melted. During the smelting process, 5 tons of raw materials are added and the smelting time is 6 hours.

[0011] The proportion of industrial alumina, magnesium powder and dust ash used in the raw materials is conducive to fully consuming the electric furnace dust ash without affecting the quality of smelting magnesium aluminum spinel. The high magnesium content in the electric furnace dust ash is used to replace part of the magnesium powder ingredients during the batching process, reducing the cost of raw material use. At the same time, due to the fine particle size of the electric furnace dust ash, the dispersion between the raw materials is improved during the mixing process, making the components uniform during the mixing process, which is conducive to improving the uniformity of the product's mineral phase and organizational structure. By crushing the raw material mixed bricks, it is convenient for the particles to fully contact with each other, which can accelerate the Mg content in the raw materials. 2+ With Al 3+ diffusion, promoting the formation of Mg-Al-Spinel phase.

[0012] The calcined alumina powder used in the original material has a high sintering temperature, a small original crystal size, a suitable particle size distribution, a stable sintering density, a uniform shrinkage rate and a high activity; and the α-alumina has a uniform particle size, is easy to disperse, has stable chemical properties, moderate high-temperature shrinkage performance, good sintering performance, high conversion rate, low sodium content and other excellent properties, which promote the sintering formation of the spinel phase and improve the quality of the spinel finished product.

[0013] The beneficial effects of the present invention are: 1. The electric furnace dust is preformed into bricks by batching and molding. The bricks are crushed and added to the electric arc furnace to prepare magnesia-alumina spinel raw materials, avoiding dust pollution and SO2 emissions caused by adding dust directly into the electric arc furnace. 2 , nitrogen oxides exceeding the standard, etc., which is conducive to the green development of electric furnace smelting process and reduces pollution to the environment; 2. The electric furnace dust is preformed into bricks through batching and molding, ensuring that the MgO and Al in the brick raw materials are 2 O 3 Stable composition. The bricks can be fully melted after being crushed and added to the electric arc furnace for smelting, successfully avoiding the disadvantage that the dust ash directly added to the electric furnace is difficult to fully melt. The synthesized magnesium aluminum spinel has stable chemical composition and good crystallization. At the same time, this method can reuse the dust ash consumed in batches in the electric furnace, reduce production costs, and is conducive to the sustainable development of electric furnace production. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is the X-ray diffraction analysis diagram of the fused spinel prepared in Example 3. DETAILED DESCRIPTION

[0015] The present invention will be further described in detail below with reference to specific embodiments. Example 1

[0016] A magnesium-aluminum spinel smelted by using electric furnace dust removal ash comprises the following raw material components and added weight portions: 72 parts of industrial alumina powder with a particle size of ≤0.15 mm, 28 parts of magnesium oxide powder with a particle size of ≤0.075 mm, 2 parts of dust removal ash with a particle size of ≤0.063 mm, and 1 part of aluminum phosphate binder.

[0017] A preparation method for smelting magnesia-alumina spinel using electric furnace dust removal ash comprises the following steps: Step 1: Ingredients: weigh the raw materials in proportion according to the formula requirements for smelting magnesia-alumina spinel; Step 2: Premixing: Add the weighed industrial alumina powder, magnesium oxide powder and dust removal ash into the vertical double cone sand mixer for premixing for 15 minutes. After mixing, store in a packaging bag and seal it for later use. Step 3: Mixing: Mix the raw materials of magnesium aluminum spinel, pour the premixed raw materials into a strong sand mixer, mix and stir for 3 to 5 minutes, evenly add the binder after mixing, and continue to mix and stir for 10 to 15 minutes until the raw materials are evenly dispersed and mixed into a mud material for standby use; Step 4: Add materials: Use a feeder to evenly add the clay into the molding silo, and keep the clay evenly dispersed during the adding process; Step 5: Molding: Use a 300t hydraulic press to press the mud in the silo into bricks of 280mm×100mm×100mm size; Step 6: Drying: The formed bricks are stacked on the kiln car as a whole and dried in a tunnel kiln at a temperature of 100°C for 48 hours. Step 7: Crushing: Put the fully dried bricks into a jaw crusher or a vertical crusher for crushing. The crushed bricks are transported by a bucket elevator to a designated silo for standby use. Step 8. Smelting: The capacity of the three-phase electric arc furnace transformer used is 3600KVA, the smelting voltage is 160V, and the normal operating current is 4000-6000A. Before the start of smelting, lay 200mm thick broken brick raw materials on the bottom of the furnace. After the bottom layer of raw materials is melted, add the broken brick raw materials in the silo into the electric arc furnace in small amounts and multiple times to ensure that the raw materials are fully melted. During the smelting process, 5 tons of raw materials are added and the smelting time is 6 hours. Example 2

[0018] A magnesium-aluminum spinel smelted by using electric furnace dust removal ash comprises the following raw material components and the added weight proportions: 75 parts of industrial alumina powder with a particle size of ≤0.15 mm, 25 parts of magnesium oxide powder with a particle size of ≤0.075 mm, 3 parts of dust removal ash with a particle size of ≤0.063 mm, and additionally 1 part of aluminum phosphate and 1 part of hydroxymethyl cellulose as binders.

[0019] A preparation method for smelting magnesia-alumina spinel using electric furnace dust removal ash comprises the following steps: Step 1: Ingredients: weigh the raw materials in proportion according to the formula requirements for smelting magnesia-alumina spinel; Step 2: Premixing: Add the weighed industrial alumina powder, magnesium oxide powder and dust removal ash into the vertical double cone sand mixer for premixing for 15 minutes. After mixing, store in a packaging bag and seal it for later use. Step 3: Mixing: Mix the raw materials of magnesium aluminum spinel, pour the premixed raw materials into a strong sand mixer, mix and stir for 3 to 5 minutes, evenly add the binder after mixing, and continue to mix and stir for 10 to 15 minutes until the raw materials are evenly dispersed and mixed into a mud material for standby use; Step 4: Add materials: Use a feeder to evenly add the clay into the molding silo, and keep the clay evenly dispersed during the adding process; Step 5: Molding: Use a 300t hydraulic press to press the mud in the silo into bricks of 280mm×100mm×100mm size; Step 6, Drying: The formed bricks are stacked on the kiln car as a whole and dried in a tunnel kiln drying kiln at a drying temperature of 120°C for 40 hours; Step 7: Crushing: Put the fully dried bricks into a jaw crusher or a vertical crusher for crushing. The crushed bricks are transported by a bucket elevator to a designated silo for standby use. Step 8. Smelting: The capacity of the three-phase electric arc furnace transformer used is 3600KVA, the smelting voltage is 160V, and the normal operating current is 4000-6000A. Before the start of smelting, lay 200mm thick broken brick raw materials on the bottom of the furnace. After the bottom layer of raw materials is melted, add the broken brick raw materials in the silo into the electric arc furnace in small amounts and multiple times to ensure that the raw materials are fully melted. During the smelting process, 5 tons of raw materials are added and the smelting time is 6 hours. Example 3

[0020] A magnesium-aluminum spinel smelted by using electric furnace dust removal ash comprises the following raw material components and the added weight proportions: 72 parts of industrial alumina powder with a particle size of ≤0.15 mm, 28 parts of magnesium oxide powder with a particle size of ≤0.075 mm, 5 parts of dust removal ash with a particle size of ≤0.063 mm, and 1 part of hydroxymethyl cellulose and 2 parts of yellow dextrin as binders.

[0021] A preparation method for smelting magnesia-alumina spinel using electric furnace dust removal ash comprises the following steps: Step 1: Ingredients: weigh the raw materials in proportion according to the formula requirements for smelting magnesia-alumina spinel; Step 2: Premixing: Add the weighed industrial alumina powder, magnesium oxide powder and dust removal ash into the vertical double cone sand mixer for premixing for 15 minutes. After mixing, store in a packaging bag and seal it for later use. Step 3: Mixing: Mix the raw materials of magnesium aluminum spinel, pour the premixed raw materials into a strong sand mixer, mix and stir for 3 to 5 minutes, evenly add the binder after mixing, and continue to mix and stir for 10 to 15 minutes until the raw materials are evenly dispersed and mixed into a mud material for standby use; Step 4: Add materials: Use a feeder to evenly add the clay into the molding silo, and keep the clay evenly dispersed during the adding process; Step 5: Molding: Use a 300t hydraulic press to press the mud in the silo into bricks of 280mm×100mm×100mm size; Step 6: Drying: The formed bricks are stacked on the kiln car as a whole and dried in a tunnel kiln at a temperature of 150°C for 36 hours. Step 7: Crushing: Put the fully dried bricks into a jaw crusher or a vertical crusher for crushing. The crushed bricks are transported by a bucket elevator to a designated silo for standby use. Step 8. Smelting: The capacity of the three-phase electric arc furnace transformer used is 3600KVA, the smelting voltage is 160V, and the normal operating current is 4000-6000A. Before the start of smelting, lay 200mm thick broken brick raw materials on the bottom of the furnace. After the bottom layer of raw materials is melted, add the broken brick raw materials in the silo into the electric arc furnace in small amounts and multiple times to ensure that the raw materials are fully melted. During the smelting process, 5 tons of raw materials are added and the smelting time is 6 hours.

[0022] The fused spinel prepared in Examples 1-3 was sampled and sent for inspection, and the test results of its main chemical composition and physical properties are as follows:

[0023] Comprehensive comparison shows that the chemical composition of the fused spinel product of Example 3 is high in magnesium content and has the highest bulk density. The fused spinel of Example 3 was subjected to x-ray diffraction analysis. The analysis results show that the fused synthetic material phase is mainly magnesium-aluminum spinel and a small amount of corundum, with the spinel phase accounting for 98% and having a high purity.

[0024] The parts of the present invention that are not described in detail are prior art. The above embodiments will help relevant persons in the art to further understand the present invention, but do not limit the present invention in any form. Without departing from the scope of the present invention defined by the attached claims, various changes in form, details or equivalents made using the present invention are all within the protection scope of the present invention.

Claims

1. A magnesium-aluminum spinel smelted by using electric furnace dust removal ash, characterized in that: The invention comprises the following raw material components and the added weight proportions: 68-75 parts of industrial alumina powder with a particle size of ≤0.15mm, 20-28 parts of magnesium oxide powder with a particle size of ≤0.075mm, 2-5 parts of dust removal ash with a particle size of ≤0.063mm, and 1-3 parts of an additional binder.

2. The magnesium-aluminum spinel smelted by using electric furnace dust ash according to claim 1 is characterized in that: Industrial alumina powder is calcined alumina powder.

3. The magnesium-aluminum spinel smelted by using electric furnace dust ash according to claim 1, characterized in that: The magnesium oxide powder is 90-95wt% of light-burned magnesium powder, dead-burned magnesium powder or a combination of the two.

4. The magnesium-aluminum spinel smelted by using electric furnace dust ash according to claim 1 is characterized in that: The binder is one or more combinations of aluminum phosphate, hydroxymethyl cellulose, pulp waste liquid and yellow dextrin.

5. A method for preparing spinel by smelting electric furnace dust ash according to claim 1, characterized in that: The following steps are involved: Step 1: Ingredients: weigh the raw materials in proportion according to the formula requirements for smelting magnesia-alumina spinel; Step 2: Premixing: Add the weighed industrial alumina powder, magnesium oxide powder and dust removal ash into the vertical double cone sand mixer for premixing for 15 minutes. After mixing, store in a packaging bag and seal it for later use. Step 3: Mixing: Mix the raw materials of magnesium aluminum spinel, pour the pre-mixed raw materials into a strong sand mixer, mix and stir for 3 to 5 minutes, evenly add the binder after mixing, and continue to mix and stir for 10 to 15 minutes until the raw materials are evenly dispersed and mixed into a mud material for standby use; Step 4: Add materials: Use a feeder to evenly add the clay into the molding silo, and keep the clay evenly dispersed during the adding process; Step 5: Molding: Use a 300t hydraulic press to press the mud in the silo into bricks of 280mm×100mm×100mm size; Step 6: Drying: The formed bricks are stacked on the kiln car as a whole and dried in a tunnel kiln at a temperature of 100-150°C for 36-48 hours. Step 7: Crushing: Put the fully dried bricks into a jaw crusher or a vertical crusher for crushing. The crushed bricks are transported by a bucket elevator to a designated silo for standby use. Step 8. Smelting: The capacity of the three-phase electric arc furnace transformer used is 3600KVA, the smelting voltage is 160V, and the normal operating current is 4000-6000A. Before the start of smelting, lay 200mm thick broken brick raw materials on the bottom of the furnace. After the bottom layer of raw materials is melted, add the broken brick raw materials in the silo into the electric arc furnace in small amounts and multiple times to ensure that the raw materials are fully melted. During the smelting process, 5 tons of raw materials are added and the smelting time is 6 hours.

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