Magnesium-aluminum spinel smelted by using dust ash of electric furnace and preparation method thereof

Abstract

This invention discloses a method for smelting magnesium-aluminum spinel using electric arc furnace dust and its preparation. The raw materials include industrial alumina powder, magnesium oxide powder, dust, and a binder. The method uses relatively few raw materials and has a relatively simple process. The electric arc furnace dust is used as a batching material to form precast brick blanks. The brick blanks are then crushed and added to the electric arc furnace, ensuring the stability of the MgO and Al2O3 components in the brick blanks. This avoids the drawbacks of dust pollution, SO2, and excessive nitrogen oxides caused by directly adding dust to the electric arc furnace, thus reducing environmental pollution. Furthermore, it can produce magnesium-aluminum spinel raw materials with better performance. The batch consumption and reuse of electric arc furnace dust is conducive to the green development of electric arc furnace smelting technology.

Description

Technical Field

[0001] This invention belongs to the field of composite refractory material production technology, specifically relating to a magnesium aluminum spinel smelted using electric furnace dust and its preparation method. Background Technology

[0002] As is well known, magnesium aluminum spinel is a composite mineral composed of MgO and Al2O3. It possesses advantages such as high melting point, high strength, low thermal expansion coefficient, and corrosion resistance, making it a high-quality refractory material. Currently, there are two methods for synthesizing magnesium aluminum spinel: the electrofusion method and the sintering method. The electrofusion method, as one of the basic methods for synthesizing magnesium aluminum spinel raw materials, has advantages over the sintering method, including simpler process, higher bulk density, more stable chemical composition, and larger crystal size.

[0003] The electrofusion method uses a three-phase electric arc furnace to melt raw materials such as alumina and magnesia powder into a liquid state. After cooling and crystallization, it becomes solid magnesium aluminate spinel. Since the raw materials are mostly powdery particles, they easily diffuse and generate dust pollution during the melting and liquefaction process. Therefore, a dust collection device is installed inside the electric furnace to collect the dust. Studies have shown that the main components of the electric furnace dust are 40–50 wt% Al₂O₃, 45–50 wt% MgO, and small amounts of other impurities. During normal production, small batches of the dust collected by the dust collection device are added back to the electric furnace for smelting. Compared to the raw materials, the dust is lighter and tends to float on the surface of the molten metal during smelting, making it difficult to melt. This results in low purity and poor appearance of the smelted magnesium aluminate spinel, affecting product quality.

[0004] Therefore, how to recycle electric furnace dust without affecting the quality of magnesium aluminum spinel products, and how to improve the recycling rate of electric furnace dust, have become urgent problems for technicians in this field. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for smelting magnesium-aluminum spinel using electric arc furnace dust and its preparation. This method uses fewer raw materials and has a relatively simple process. The electric arc furnace dust is used as a batching material to form precast brick blanks. These blanks are then crushed and added to the electric arc furnace, ensuring the stability of the MgO and Al2O3 components in the brick blanks. This avoids the drawbacks of directly adding dust to the electric arc furnace, such as dust pollution, excessive SO2 and nitrogen oxides, thus reducing environmental pollution. Furthermore, it can produce magnesium-aluminum spinel raw materials with superior performance. The batch consumption and reuse of electric arc furnace dust is beneficial for the green development of electric arc furnace smelting processes.

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

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

[0008] The magnesium oxide powder is 90-95 wt% of one or a combination of two of light-burned magnesium powder and heavy-burned magnesium powder.

[0009] The binder is one or more of aluminum phosphate, hydroxymethyl cellulose, pulp waste liquor, and xanthodextrin.

[0010] A method for preparing spinel by smelting dust from an electric furnace includes the following steps:

[0011] Step 1, Ingredients: Weigh and mix each raw material according to the formula requirements for smelting magnesium aluminum spinel;

[0012] Step 2, Premixing: Add the weighed industrial alumina powder, magnesium oxide powder, and dust to the vertical double cone sand mixer for premixing. The mixing time is 15 minutes. After mixing, store in a sealed ton bag for later use.

[0013] Step 3: Mixing: Mix the magnesium aluminum spinel raw materials. Pour the premixed raw materials into a high-power sand mixer and mix for 3-5 minutes. After mixing, add the binder evenly and continue mixing for 10-15 minutes until the raw materials are evenly dispersed and mixed into a mud for later use.

[0014] Step 4: Feeding: Use a feeder to evenly add the mud into the molding hopper, keeping the mud evenly dispersed during the feeding process;

[0015] Step 5: Molding: Use a 300t hydraulic press to press the mud in the silo into brick blanks with dimensions of 280mm×100mm×100mm;

[0016] Step 6, Drying: The formed brick blanks are stacked on the kiln car and dried in the tunnel kiln drying kiln at a temperature of 100-150℃ for 36-48 hours.

[0017] Step 7: Crushing: Place the fully dried brick blanks into a jaw crusher or vertical crusher for crushing. The crushed brick blank raw materials are then transferred to a designated silo by a bucket elevator for later use.

[0018] Step 8, Smelting: The three-phase electric arc furnace transformer has a capacity of 3600KVA, a smelting voltage of 160V, and a normal operating current of 4000~6000A. Before smelting begins, a 200mm thick layer of crushed brick blank raw material is laid at the bottom of the furnace. After the bottom layer of raw material melts, the crushed brick blank raw material in the hopper is added to the electric arc furnace in small amounts multiple times to ensure that the raw material is fully melted. During the smelting process, 5 tons of raw material are added, and the smelting time is 6 hours.

[0019] The raw materials utilize a specific ratio of industrial alumina, magnesium powder, and electric furnace dust. This ratio ensures the efficient use of electric furnace dust without compromising the quality of the smelted magnesium-aluminum spinel. The high magnesium content of the electric furnace dust allows for the substitution of some magnesium powder, reducing raw material costs. Simultaneously, the fine particle size of the electric furnace dust improves the dispersion of raw materials during mixing, resulting in more uniform components and enhancing the homogeneity of the mineral phase and microstructure in the final product. Crushing the raw materials before molding the bricks facilitates sufficient contact between particles, accelerating the extraction of magnesium from the raw materials. 2+ With Al 3+ The diffusion of [something] promotes the formation of the magnesium aluminum spinel phase.

[0020] The calcined alumina micro powder used in the raw material has a high calcination temperature, small primary crystal size, suitable particle size distribution, stable sintering density, uniform shrinkage rate, and high activity. Furthermore, the α-alumina has 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 spinel phase and improve the quality of finished spinel products.

[0021] The beneficial effects of this invention are as follows:

[0022] 1. The electric arc furnace dust is pre-formed into brick blanks through batching and molding. The brick blanks are then added to the electric arc furnace in a crushed form to prepare magnesium aluminum spinel raw materials. This avoids dust pollution, SO2 and nitrogen oxide exceeding the standard caused by directly adding the dust to the electric arc furnace, which is conducive to the green development of electric arc furnace smelting process and reduces environmental pollution.

[0023] 2. By pre-forming electric arc furnace dust into brick blanks through a batching and molding process, the stability of MgO and Al2O3 components in the brick blank raw materials is ensured. The brick blanks are then crushed and added to the electric arc furnace for smelting, allowing for complete melting. This successfully avoids the drawback of insufficient melting when dust is directly added to the electric arc furnace. The synthesized magnesium aluminum spinel has a stable chemical composition and good crystallinity. Furthermore, this method allows for the batch consumption and reuse of electric arc furnace dust, reducing production costs and promoting the sustainable development of electric arc furnace production. Attached Figure Description

[0024] Figure 1 The image shows the X-ray diffraction pattern of the fused spinel prepared in Example 3. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to specific embodiments. Example 1

[0026] A magnesium-aluminum spinel smelted using electric furnace dust comprises the following raw material components and the following weight proportions: 72 parts of industrial alumina powder with a particle size ≤0.15mm, 28 parts of magnesium oxide powder with a particle size ≤0.075mm, 2 parts of dust with a particle size ≤0.063mm, and 1 part of aluminum phosphate binder.

[0027] A method for preparing magnesium aluminum spinel by smelting ash from an electric furnace includes the following steps:

[0028] Step 1, Ingredients: Weigh and mix each raw material according to the formula requirements for smelting magnesium aluminum spinel;

[0029] Step 2, Premixing: Add the weighed industrial alumina powder, magnesium oxide powder, and dust to the vertical double cone sand mixer for premixing. The mixing time is 15 minutes. After mixing, store in a sealed ton bag for later use.

[0030] Step 3: Mixing: Mix the magnesium aluminum spinel raw materials. Pour the premixed raw materials into a high-power sand mixer and mix for 3-5 minutes. After mixing, add the binder evenly and continue mixing for 10-15 minutes until the raw materials are evenly dispersed and mixed into a mud for later use.

[0031] Step 4: Feeding: Use a feeder to evenly add the mud into the molding hopper, keeping the mud evenly dispersed during the feeding process;

[0032] Step 5: Molding: Use a 300t hydraulic press to press the mud in the silo into brick blanks with dimensions of 280mm×100mm×100mm;

[0033] Step 6, Drying: The formed brick blanks are stacked on the kiln car and dried in the tunnel kiln drying kiln at a temperature of 100℃ for 48 hours.

[0034] Step 7: Crushing: Place the fully dried brick blanks into a jaw crusher or vertical crusher for crushing. The crushed brick blank raw materials are then transferred to a designated silo by a bucket elevator for later use.

[0035] Step 8, Smelting: The three-phase electric arc furnace transformer has a capacity of 3600KVA, a smelting voltage of 160V, and a normal operating current of 4000~6000A. Before smelting begins, a 200mm thick layer of crushed brick blank raw material is laid at the bottom of the furnace. After the bottom layer of raw material melts, the crushed brick blank raw material in the hopper is added to the electric arc furnace in small amounts multiple times to ensure that the raw material is fully melted. During the smelting process, 5 tons of raw material are added, and the smelting time is 6 hours. Example 2

[0036] A magnesium aluminum spinel smelted using electric furnace dust includes the following raw material components and the following weight proportions: 75 parts of industrial alumina powder with a particle size ≤0.15mm, 25 parts of magnesium oxide powder with a particle size ≤0.075mm, 3 parts of dust with a particle size ≤0.063mm, and 1 part of aluminum phosphate and 1 part of hydroxymethyl cellulose as binders.

[0037] A method for preparing magnesium aluminum spinel by smelting ash from an electric furnace includes the following steps:

[0038] Step 1, Ingredients: Weigh and mix each raw material according to the formula requirements for smelting magnesium aluminum spinel;

[0039] Step 2, Premixing: Add the weighed industrial alumina powder, magnesium oxide powder, and dust to the vertical double cone sand mixer for premixing. The mixing time is 15 minutes. After mixing, store in a sealed ton bag for later use.

[0040] Step 3: Mixing: Mix the magnesium aluminum spinel raw materials. Pour the premixed raw materials into a high-power sand mixer and mix for 3-5 minutes. After mixing, add the binder evenly and continue mixing for 10-15 minutes until the raw materials are evenly dispersed and mixed into a mud for later use.

[0041] Step 4: Feeding: Use a feeder to evenly add the mud into the molding hopper, keeping the mud evenly dispersed during the feeding process;

[0042] Step 5: Molding: Use a 300t hydraulic press to press the mud in the silo into brick blanks with dimensions of 280mm×100mm×100mm;

[0043] Step 6, Drying: The formed brick blanks are stacked on the kiln car and dried in the tunnel kiln drying kiln at a temperature of 120℃ for 40 hours.

[0044] Step 7: Crushing: Place the fully dried brick blanks into a jaw crusher or vertical crusher for crushing. The crushed brick blank raw materials are then transferred to a designated silo by a bucket elevator for later use.

[0045] Step 8, Smelting: The three-phase electric arc furnace transformer has a capacity of 3600KVA, a smelting voltage of 160V, and a normal operating current of 4000~6000A. Before smelting begins, a 200mm thick layer of crushed brick blank raw material is laid at the bottom of the furnace. After the bottom layer of raw material melts, the crushed brick blank raw material in the hopper is added to the electric arc furnace in small amounts multiple times to ensure that the raw material is fully melted. During the smelting process, 5 tons of raw material are added, and the smelting time is 6 hours. Example 3

[0046] A magnesium-aluminum spinel smelted using electric furnace dust includes the following raw material components and the following weight proportions: 72 parts of industrial alumina powder with a particle size ≤0.15mm, 28 parts of magnesium oxide powder with a particle size ≤0.075mm, 5 parts of dust with a particle size ≤0.063mm, 1 part of hydroxymethyl cellulose binder, and 2 parts of dextrin.

[0047] A method for preparing magnesium aluminum spinel by smelting ash from an electric furnace includes the following steps:

[0048] Step 1, Ingredients: Weigh and mix each raw material according to the formula requirements for smelting magnesium aluminum spinel;

[0049] Step 2, Premixing: Add the weighed industrial alumina powder, magnesium oxide powder, and dust to the vertical double cone sand mixer for premixing. The mixing time is 15 minutes. After mixing, store in a sealed ton bag for later use.

[0050] Step 3: Mixing: Mix the magnesium aluminum spinel raw materials. Pour the premixed raw materials into a high-power sand mixer and mix for 3-5 minutes. After mixing, add the binder evenly and continue mixing for 10-15 minutes until the raw materials are evenly dispersed and mixed into a mud for later use.

[0051] Step 4: Feeding: Use a feeder to evenly add the mud into the molding hopper, keeping the mud evenly dispersed during the feeding process;

[0052] Step 5: Molding: Use a 300t hydraulic press to press the mud in the silo into brick blanks with dimensions of 280mm×100mm×100mm;

[0053] Step 6, Drying: The formed brick blanks are stacked on the kiln car and dried in the tunnel kiln drying kiln at a temperature of 150℃ for 36 hours.

[0054] Step 7: Crushing: Place the fully dried brick blanks into a jaw crusher or vertical crusher for crushing. The crushed brick blank raw materials are then transferred to a designated silo by a bucket elevator for later use.

[0055] Step 8, Smelting: The three-phase electric arc furnace transformer has a capacity of 3600KVA, a smelting voltage of 160V, and a normal operating current of 4000~6000A. Before smelting begins, a 200mm thick layer of crushed brick blank raw material is laid at the bottom of the furnace. After the bottom layer of raw material melts, the crushed brick blank raw material in the hopper is added to the electric arc furnace in small amounts multiple times to ensure that the raw material is fully melted. During the smelting process, 5 tons of raw material are added, and the smelting time is 6 hours.

[0056] Samples of the fused spinel prepared in Examples 1-3 were sent for testing, and the results of their main chemical composition and physical properties are as follows:

[0057]

[0058] In summary, the electrofused spinel product of Example 3 has a high magnesium content and the highest bulk density. X-ray diffraction analysis of the electrofused spinel from Example 3 showed that the main phases of the electrofused composite material were magnesium aluminum spinel and a small amount of corundum, with the spinel phase accounting for 98%, indicating high purity.

[0059] The parts of this invention not described in detail are prior art. The above embodiments will help those skilled in the art to further understand this invention, but do not limit this invention in any way. Various changes in form, detail, or equivalents made using this invention without departing from the scope of the appended claims are all within the protection scope of this invention.

Claims

1. A magnesium-aluminum spinel smelted using electric furnace dust, characterized in that, It contains the following raw material components and the following weight parts: 68-75 parts of industrial alumina powder with a particle size ≤0.15mm, 20-28 parts of magnesium oxide powder with a particle size ≤0.075mm, 2-5 parts of electric furnace dust with a particle size ≤0.063mm, and 1-3 parts of added binder. The main components of electric furnace dust are 40-50 wt% Al2O3, 45-50 wt% MgO, and a small amount of other impurities.

2. The magnesium aluminum spinel smelted using electric furnace dust as described in claim 1, characterized in that: Industrial alumina powder is calcined alumina micro powder.

3. The magnesium aluminum spinel smelted using electric furnace dust as described in claim 1, characterized in that: Magnesium oxide powder is 90-95 wt% of one or a combination of two types of light-burned magnesia and heavy-burned magnesia powder.

4. The magnesium aluminum spinel smelted using electric furnace dust as described in claim 1, characterized in that: The binder is one or more of aluminum phosphate, hydroxymethyl cellulose, pulp waste liquor, and xanthodextrin.

5. A method for preparing magnesium aluminum spinel by smelting ash from an electric furnace according to claim 1, characterized in that, Includes the following steps: Step 1, Ingredients: Weigh and mix each raw material according to the formula requirements for smelting magnesium aluminum spinel; Step 2, Premixing: Add the weighed industrial alumina powder, magnesium oxide powder, and electric furnace dust to the vertical double cone sand mixer for premixing. The mixing time is 15 minutes. After mixing, store in a sealed ton bag for later use. Step 3: Mixing: Mix the magnesium aluminum spinel raw materials. Pour the premixed raw materials into a high-power sand mixer and mix for 3-5 minutes. After mixing, add the binder evenly and continue mixing for 10-15 minutes until the raw materials are evenly dispersed and mixed into a mud for later use. Step 4: Feeding: Use a feeder to evenly add the mud into the molding hopper, keeping the mud evenly dispersed during the feeding process; Step 5: Molding: Use a 300t hydraulic press to press the mud in the silo into brick blanks with dimensions of 280mm×100mm×100mm; Step 6, Drying: The formed brick blanks are stacked on the kiln car and dried in the tunnel kiln drying kiln at a temperature of 100-150℃ for 36-48 hours. Step 7: Crushing: Place the fully dried brick blanks into a jaw crusher or vertical crusher for crushing. The crushed brick blank raw materials are then transferred to a designated silo by a bucket elevator for later use. Step 8, Smelting: The transformer capacity of the three-phase electric arc furnace used is 3600KVA, the smelting voltage is 160V, and the normal operating current is 4000-6000A. Before smelting begins, a 200mm thick layer of crushed brick blank raw material is laid at the bottom of the furnace. After the bottom layer of raw material melts, the crushed brick blank raw material in the hopper is added to the electric arc furnace in small amounts multiple times to ensure that the raw material is fully melted. During the smelting process, 5 tons of raw material are added, and the smelting time is 6 hours.

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