Manufacturing method of permanent magnetic ferrite rotary kiln refractory brick

Abstract

The invention relates to a manufacturing method of a permanent magnetic ferrite rotary kiln refractory brick. The method comprises the following steps: step 1, preparing a first component; step 2, preparing a second component; step 3, preparing a transition component; the method solves the problem that wet materials are infiltrated into the refractory bricks or infiltrated into gaps of the refractory bricks in wet permanent magnetic ferrite production. Corrosion of damp and hot water vapor to the refractory bricks and damage of the refractory bricks caused by rapid moisture gasification in the damp area when the temperature area in the kiln changes are avoided. And when the materials fall off, the materials are components in the permanent magnetic ferrite components, so that the fluctuation of the materials is reduced, and the quality fluctuation or quality accidents of a large batch of materials are avoided.

Description

Technical Field

[0001] The invention relates to a method for preparing refractory bricks, in particular to a method for preparing permanent magnet ferrite rotary kiln refractory bricks, and belongs to the technical field of permanent magnet ferrite magnetic powder production equipment. Background Art

[0002] Permanent ferrite pre-sintered powder is widely used in plastic magnets, toys, electro-acoustic equipment, office automation, auto parts, sensor materials, optoelectronic materials, pigments, catalysts and other fields. At present, permanent ferrite powder is mainly made by mixing, sintering and grinding red iron oxide and auxiliary materials such as barium carbonate, strontium carbonate and calcium carbonate.

[0003] The conventional process is: first wet-mix red iron oxide, barium carbonate, strontium carbonate and auxiliary materials, grind the mixed slurry into about 1-2um through a ball mill, with a water content of about 50%-60%, and pump the slurry into a rotary kiln through a mud pump or other equipment or dehydrate it to 30-40% through a dehydrator, and then pump it into the kiln through an injection pump, and the temperature is gradually heated from about 250°C to about 1300°C.

[0004] The lining of the sintering rotary kiln is mainly composed of refractory bricks and thermal insulation bricks. The layer in contact with the material is refractory bricks, which are mainly pressed by calcined hard clay, soft clay, water glass and other materials.

[0005] The disadvantages of the current wet process ferrite pre-burned rotary kiln refractory bricks are:

[0006] (1) Refractory materials are easy to fall off: Since the slurry or slag entering the kiln contains 30-60% water, the material will infiltrate the refractory material or the water will penetrate into the gaps of the refractory bricks after contacting the refractory bricks. During the heating process, the water changes from liquid to gas, generating continuous force, which makes the refractory bricks easy to lose strength. As the material continues to enter, the refractory bricks are easily corroded and fall off.

[0007] (2) Contaminated ferrite materials: Since refractory bricks and refractory clay contain about 35%-70% oxidation rate, as well as materials such as silicon dioxide and sodium silicate, when these materials fall off and enter the main product permanent magnet ferrite material, it often leads to a decrease in magnetic properties, and sometimes even causes the main indicator, residual magnetism, to drop by 10-15%, and the shrinkage ratio to change by 3%-5%, causing the processing dimensions of downstream customers to exceed the tolerance range, resulting in unqualified products, batch quality fluctuations, and even quality accidents.

[0008] Therefore, it is necessary to design the manufacturing process of permanent magnet ferrite rotary kiln lining refractory bricks according to the wet permanent magnet ferrite production process, the functional properties of permanent magnet materials and the quality control requirements, so as to make the refractory bricks more adaptable to the high temperature and humid production process environment.

[0009] The rotary kiln bricks currently published are mainly for cement, steel production and other fields. The types of rotary kiln refractory bricks include magnesia chrome bricks, dolomite bricks, magnesia zircon bricks, magnesia calcium zircon bricks, magnesia iron spinel bricks, magnesia aluminum spinel bricks, iron aluminum spinel bricks and other material types. This patent mainly targets the production process characteristics and quality requirements of ferrites, and adopts a binary formula of iron strontium magnetite component and high aluminum component. In the search, there are no documents and patents for refractory brick process design for ferrite product production process and quality requirements. Summary of the invention

[0010] The present invention is aimed at the technical problems existing in the prior art, and provides a method for manufacturing permanent magnet ferrite rotary kiln refractory bricks. In this scheme, iron oxide red, strontium carbonate, calcium carbonate, kaolin, etc. are mixed and kneaded according to a set ratio to make refractory bricks. This method solves the problem of wet materials infiltrating into refractory bricks or penetrating into the gaps of refractory bricks in the production of wet permanent magnet ferrite. It avoids the corrosion of refractory bricks by wet hot water steam, and the damage of refractory bricks caused by rapid gasification of moisture in the wet area when the temperature zone in the kiln changes. And when the material falls off, since the material is a component of the permanent magnet ferrite, the material fluctuation is reduced, avoiding large-scale material quality fluctuations or quality accidents.

[0011] In order to achieve the above object, the technical solution of the present invention is as follows: a method for manufacturing permanent ferrite rotary kiln refractory bricks, the method comprising the following steps:

[0012] Step 1: Preparation method of the first component: Determine the total amount according to the specifications of the rotary kiln, and mix in a mixer for 30 to 60 minutes according to the mass fraction of iron ore red 70% to 87%, strontium carbonate 5% to 25%, calcium carbonate 0.1% to 0.5%, chromium oxide 0.1% to 1.5%, and water 5-13%.

[0013] Step 2: Preparation method of the second component: 45% to 65% alumina, 35% to 52% clay, 3% to 5% water, mix in a mixer for 30 to 60 minutes,

[0014] Step 3: Preparation method of transition component: Mix the first component and the second component in a ratio of 1:2-3, and knead in a mixer for 30 minutes.

[0015] Step 4: Forming and pressing bricks: Fill the forming mold of the refractory brick press with materials in a volume percentage ratio of 1:1.5:3, and pressurize both sides at 2.5-2.8MPa. The corresponding side of the first component material is the inner side, and the mold mark is "I". The corresponding part of the second component material is the outer side, and the mold mark is "O". The inner and outer sides are stacked separately.

[0016] Step 5: Heat treatment. In the heat treatment furnace, the heat preservation system is sequentially passed: 130℃ insulation, 200℃ insulation, 500℃ insulation, and 700℃ insulation, to fully and evenly drain and harden, and prepare for high-temperature firing.

[0017] Step 6: Palletizing: The heat-treated bricks are palletized to prepare for firing.

[0018] Step 7: Dense sintering of refractory bricks In the tunnel kiln, the temperature is in the range of 1250-1350℃ for the first stage, at which time the first component area of ​​the refractory brick produces an iron-strontium hexagonal magnetoplumbite structure. The temperature is raised to about 1350-1500℃ for the second stage sintering, producing a common high-aluminum spinel refractory structure.

[0019] Compared with the prior art, the present invention has the following advantages: 1. Resistance to chloride ion corrosion. Red iron oxide is a common raw material in the wet process of ferrite. Since red iron oxide comes from the Rushena process, it contains about 0.1% to 0.2% chloride ions, and in severe cases it can reach about 4%. The refractory bricks involved in this patent have better tolerance to chloride ions than conventional refractory bricks. 2. Resistance to water vapor expansion damage. Due to the high temperature, the first component area forms a dense hexagonal crystal structure with ceramic properties. During the production process of permanent ferrite magnetic powder, the wet material is on the dense layer of dense ceramic properties. During the movement from the tail of the kiln to the head of the kiln, the temperature gradually increases from room temperature to about 500°C. When it leaves the dense layer formed by this patent, the water has changed from liquid to gas and is drawn away by the induced draft fan. The refractory bricks are not easily penetrated and infiltrated by water, which avoids the damage to the strength of the refractory bricks. 3. Greatly weaken the destructive stress caused by water vaporization inside the refractory bricks. The refractory bricks involved in this patent can be well fused with the materials in production, basically filling the gaps of water entering the refractory bricks, avoiding the formation of high-temperature steam inside the bricks, and greatly weakening the corrosion and damage of the refractory bricks; 4. Little pollution to ferrite magnetic powder products. The first component area of ​​the refractory brick is the same as the structural component elements of the permanent magnet ferrite, and there is an intersection area in the proportion. Even if the detached part enters the material, the impact on the performance of the main product is relatively small, overcoming the risk of large-scale unqualified magnetic powder caused by the detachment of the material of conventional high-alumina bricks. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the manufacturing process of the first component,

[0021] Figure 2 Schematic diagram of the second component manufacturing process,

[0022] Figure 3 Schematic diagram of the transition part manufacturing process.

[0023] Figure 4 Schematic diagram of the overall manufacturing process of refractory bricks. DETAILED DESCRIPTION

[0024] In order to deepen the understanding of the present invention, the present embodiment is described in detail below with reference to the accompanying drawings.

[0025] Embodiment 1: In this embodiment, the special kiln bricks for permanent ferrite rotary kiln are produced, and the raw materials are iron oxide, strontium carbonate, oxidation rate, clay, water, etc. The production method of the present invention is adopted, and the specific process is as follows:

[0026] (1) Preparation of the first component: See Figure 1 , raw materials testing, weighing ingredients, mixing, and standby, the specific mass percentage is as follows: iron red 83.5%, strontium carbonate 14.5%, calcium carbonate 0.1%, chromium oxide 0.1%, and 11.0% water by weight of solid materials, mixed in a mixer for 40 minutes for standby,

[0027] (2) The second component is prepared. For details, see Figure 2 , raw material testing, jaw crushing, roller crushing, Raymond milling, weighing ingredients, mixing, standby,

[0028] Ingredients weighed: 55% alumina, 45% clay, and 5% water by weight of solid materials, mixed in a mixer for 30 minutes for later use;

[0029] (3) Preparation of transition components: See the process Figure 3 , weighing ingredients, mixing, and standby,

[0030] The first component and the second component are mixed in a ratio of 1:2, kneaded in a mixer for 30 minutes, and set aside.

[0031] (4) Molding and pressing bricks: See the process for details. Figure 4 ,

[0032] The materials are filled in the forming mold of the refractory brick press according to the volume percentage ratio of 1:1.5:3.

[0033] Double-sided pressure molding at 2.5MPa. The first component material corresponds to the inner side, and the mold mark is "I". The second component material corresponds to the outer side, and the mold mark is "O". The materials are placed according to the inner and outer sides.

[0034] (5) Heat treatment:

[0035] In the heat treatment furnace, the insulation system is passed in sequence: 130℃ insulation for 3 hours, 200℃ insulation for 2 hours, 500℃ insulation for 2 hours, and 700℃ insulation for 2 hours, to fully and evenly drain water and harden, preparing for high-temperature firing.

[0036] (6) Palletizing:

[0037] The heat-treated bricks are stacked and prepared for firing.

[0038] (7) Density sintering

[0039] The temperature of the refractory bricks in the tunnel kiln is gradually raised to 1280-1300℃ and kept for 3 hours for the first stage of sintering; then the temperature is gradually raised to 1360-138℃ and kept for 1 hour for the second stage of sintering.

[0040] The present invention manufactures a special refractory brick for a wet-process ferrite rotary kiln, which is built into the kiln body, with the "I" side pointing to the center and the "O" side pointing to the kiln barrel. During the production process, when the slurry enters the kiln, high-temperature steam is formed on the kiln bricks. At this time, the slurry or dehydrated slag fills the gaps, and a magnetic lead structure similar to the material of the bricks on the I side is generated during production, so that the kiln bricks are repaired and the refractory bricks are more durable. At the same time, no bad elements such as aluminum and silicon are introduced due to the kiln brick material, thereby avoiding fluctuations in the magnetic properties of the product.

[0041] It should be noted that the above embodiments are not intended to limit the protection scope of the present invention, and equivalent changes or substitutions made on the basis of the above technical solutions all fall within the protection scope of the claims of the present invention.

[0042] Embodiment 2: In this embodiment, the special kiln bricks for permanent ferrite rotary kiln are produced, and the raw materials are iron oxide, strontium carbonate, oxidation rate, clay, water, etc. The production method of the present invention is adopted, and the specific process is as follows:

[0043] (8) Preparation of the first component: Process see Figure 1 , raw materials testing, weighing ingredients, mixing, and standby, the specific mass percentage is as follows: iron red 76.2%, strontium carbonate 23.5%, calcium carbonate 0.2%, chromium oxide 0.1%, and 11.0% water, mix in a mixer for 50 minutes and set aside,

[0044] (9) The second component is prepared. For details, see Figure 2 , raw material testing, jaw crushing, roller crushing, Raymond milling, weighing ingredients, mixing, standby,

[0045] Weigh the ingredients: 60% alumina, 40% clay, and 5% water, mix in a mixer for 30 minutes and set aside;

[0046] (10) Preparation of transition components: Process see Figure 3 , weighing ingredients, mixing, and standby,

[0047] The first component and the second component are mixed in a ratio of 1:2, kneaded in a mixer for 30 minutes, and set aside.

[0048] (11) Molding and pressing bricks: See the process for details. Figure 4 ,

[0049] The materials are filled in the forming mold of the refractory brick press according to the volume percentage ratio of 1:2:3.5.

[0050] Double-sided pressure molding at 2.5MPa. The first component material corresponds to the inner side, and the mold mark is "I". The second component material corresponds to the outer side, and the mold mark is "O". The materials are placed according to the inner and outer sides.

[0051] (12) Heat treatment:

[0052] In the heat treatment furnace, the insulation system is passed in sequence: 130℃ insulation for 3 hours, 200℃ insulation for 1 hour, 500℃ insulation for 1 hour, and 700℃ insulation for 2 hours, to fully and evenly drain water and harden, preparing for high-temperature firing.

[0053] (13) Palletizing:

[0054] The heat-treated bricks are stacked and prepared for firing.

[0055] (14) Density sintering

[0056] The temperature of the refractory bricks in the tunnel kiln is gradually raised to 1280℃ and kept for 3 hours for the first stage of sintering; then the temperature is gradually raised to 1350℃ and kept for 1.5 hours for the second stage of sintering.

[0057] The present invention manufactures a special refractory brick for a wet-process ferrite rotary kiln, which is built into the kiln body, with the "I" side pointing to the center and the "O" side pointing to the kiln barrel. During the production process, when the slurry enters the kiln, high-temperature steam is formed on the kiln bricks. At this time, the slurry or dehydrated slag fills the gaps, and a magnetic lead structure similar to the material of the bricks on the I side is generated during production, so that the kiln bricks are repaired and the refractory bricks are more durable. At the same time, no bad elements such as aluminum and silicon are introduced due to the kiln brick material, thereby avoiding fluctuations in the magnetic properties of the product.

[0058] It should be noted that the above embodiments are not intended to limit the protection scope of the present invention, and equivalent changes or substitutions made on the basis of the above technical solutions all fall within the protection scope of the claims of the present invention.

Claims

1. A method for manufacturing permanent magnet ferrite rotary kiln refractory bricks, characterized in that: The method The following steps are involved: The following steps are involved: Step 1: Preparation method of the first component, Step 2: Preparation method of the second component, Step 3: Transition component preparation method, Step 4: Forming and pressing bricks, Step 5: Heat treatment, Step 6: Palletizing: Step 7: Density firing.

2. The method for manufacturing permanent magnet ferrite rotary kiln refractory bricks according to claim 1, characterized in that: Step 1: Preparation method of the first component: Determine the total amount according to the specifications of the rotary kiln, and the mass fraction is 70% to 84% of iron ore red, 5% to 14.5% of strontium carbonate, 0.1% to 0.5% of calcium carbonate, and 0.1% to 1.3% of chromium oxide. In addition, add 5-13% water by weight of the solid material and mix in a mixer for 30 to 60 minutes.

3. The method for manufacturing permanent magnet ferrite rotary kiln refractory bricks according to claim 1, characterized in that: Step 2: Preparation method of the second component: 42% to 65% alumina, 35% to 58% clay, and 3% to 5% water by weight of the solid material, and mix in a mixer for 30 to 60 minutes.

4. The method for manufacturing permanent magnet ferrite rotary kiln refractory bricks according to claim 1, characterized in that: Step 3: Preparation method of transition component: The first component and the second component are mixed in a ratio of 1:2-3, and kneaded in a mixer for 30 minutes.

5. The method for manufacturing permanent magnet ferrite rotary kiln refractory bricks according to claim 1, characterized in that: Step 4: Forming and pressing bricks: Fill the forming mold of the refractory brick press with materials in a volume percentage ratio of 1:1.5:3, and pressurize on both sides at 2.5-2.8MPa. The corresponding side of the first component material is the inner side, and the mold mark is "I", and the corresponding part of the second component material is the outer side, and the mold mark is "O", and the inside and outside are stacked separately.

6. The method for manufacturing permanent magnet ferrite rotary kiln refractory bricks according to claim 1, characterized in that: Step 5: Heat treatment. In the heat treatment furnace, the insulation system is passed in sequence: 130℃ insulation, 200℃ insulation, 500℃ insulation, and 700℃ insulation to fully and evenly drain water and harden, preparing for high-temperature firing.

7. The method for manufacturing permanent magnet ferrite rotary kiln refractory bricks according to claim 1, characterized in that: Step 6: Palletizing: The heat-treated bricks are palletized to prepare for firing.

8. The method for manufacturing permanent magnet ferrite rotary kiln refractory bricks according to claim 1, characterized in that: Step 7: Dense sintering: The refractory bricks are fired in the tunnel kiln at a temperature of 1250-1350℃ for the first stage, at which time the first component of the refractory bricks produces an iron-strontium hexagonal magnetoplumbite structure. The temperature is raised to about 1350-1500℃ for the second stage sintering, producing a common high-aluminum spinel refractory structure.

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