Method for installing a continuous refining furnace molybdenum electrode

Abstract

This invention discloses a method for installing molybdenum electrodes in a continuous refining furnace. First, the molybdenum electrode is evenly wrapped with hot melt adhesive tape. The electrode, with the insulating layer wrapped around it, is placed head-down on an assembly platform. A first ceramic tube is then inserted into the neck of the molybdenum electrode. By rotating the ceramic tube, the four marks on the molybdenum electrode are aligned with the four marks on the first ceramic tube. After the gap is adjusted to the acceptable level, it is fixed using wedge-shaped wooden blocks. Then, acid-resistant fire mortar is poured from the end of the first ceramic tube. After passing inspection, high-alumina mortar is applied to the supporting surface under the foundation bricks, and the lower tiles are installed. After the lower tiles are installed, dense alumina castable is applied to the inner wall of the lower tiles. After confirming the molybdenum electrode installation is qualified, ultra-high alumina mortar is applied to the inner wall of the upper tiles. The upper tiles are placed in the appropriate positions and pressed to ensure a tight fit. This invention replaces the gap-filling material between the lower tiles and the molybdenum electrode with dense alumina castable, avoiding rework caused by electrode sinking.

Description

Technical Field

[0001] This invention relates to the field of refining furnace installation technology, and more specifically, to a method for installing molybdenum electrodes in a continuous refining furnace. Background Technology

[0002] The installation of molybdenum electrodes is the most important step in the construction of a continuous refining furnace. Only after the molybdenum electrodes are installed can the subsequent construction work of the continuous refining furnace be carried out. The quality of the installation directly affects whether the continuous refining furnace can operate normally.

[0003] Taking the Qinghai Salt Lake magnesium metal plant as an example, there are a total of four continuous refining furnaces, each with 12 molybdenum electrodes, each weighing 186 kg. During the overall inspection after the completion of the first continuous refining furnace, it was found that the standard mortar joint between the molybdenum electrode and the upper and lower support tiles (513196) should be 3.5 mm, but the actual measured maximum value at the top was 6 mm, and there was a gap at the top. A thin iron wire could be inserted into the furnace body along the gap, indicating a through crack at the top, resulting in an excessively narrow gap at the bottom. A through crack at the top would cause magnesium liquid to leak out during production, potentially leading to a major accident. An excessively narrow gap at the bottom results in uneven heat dissipation from the molybdenum electrode, shortening the service life of the continuous refining furnace.

[0004] To ensure the quality of molybdenum electrode installation, it is extremely important to find a convenient, quick, and effective construction method. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for installing molybdenum electrodes in a continuous refining furnace to ensure the quality of molybdenum electrode installation.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is: a method for installing molybdenum electrodes in a continuous refining furnace, comprising the following steps: Step 1: Assemble the molybdenum electrode and its auxiliary components, including: (1) Construction of the molybdenum electrode isolation layer; The molybdenum electrode isolation layer is hot melt adhesive tape, and the molybdenum electrode is evenly wrapped with hot melt adhesive tape once. (2) Construction of molybdenum electrode and ceramic tube; Place the molybdenum electrode head-down on the assembly platform, with the insulating layer wrapped around it. Mark four points evenly spaced around the circumference of both the molybdenum electrode head and the end of the first ceramic tube. Then, insert the first ceramic tube into the neck of the molybdenum electrode, rotating the tube to align the four marks on the molybdenum electrode with the four marks on the first ceramic tube. After adjusting the gap between the first ceramic tube and the molybdenum electrode to the correct level, secure it with wedge-shaped wooden blocks. Then, pour acid-resistant fire mortar from the end of the first ceramic tube to fill the gap between the molybdenum electrode and the first ceramic tube. Install the second ceramic tube behind the molybdenum electrode, using the first ceramic tube as a reference. Step two, supporting the tile and assembling the molybdenum electrode installation, includes: (1) Installation of the lower tile blocks; Measure the height of the support surface under the foundation bricks, check and adjust the support surface of the foundation bricks according to the opening position of the steel furnace body, and after the inspection is qualified, apply high-alumina mortar to the support surface under the foundation bricks and install the lower tiles. (2) Assemble and install the molybdenum electrode; After the lower tile is installed, apply a dense alumina casting material to the inner wall of the lower tile, then place the assembled molybdenum electrode on the lower tile and press it to ensure that they fit tightly together. (3) Install the roof tiles; After confirming that the molybdenum electrode is installed correctly, apply ultra-high alumina mortar to its exposed surface. At the same time, apply ultra-high alumina mortar to the inner wall of the upper tile. After placing the upper tile in the corresponding position, press it to make them fit tightly together.

[0007] Furthermore, in step one, during the construction of the molybdenum electrode isolation layer, the molybdenum electrode is placed upright on a wooden platform, and hot melt adhesive tape is used to evenly wrap the molybdenum electrode once. During the wrapping process, one person holds the molybdenum electrode to ensure it does not shake, while another person smooths the hot melt adhesive tape with both hands and wraps it slowly and evenly.

[0008] Furthermore, the isolation layer uses a 50mm wide and 0.3mm thick hot melt adhesive tape.

[0009] Furthermore, in step one, after the molybdenum electrode and ceramic tube are installed, a steel ruler is used to measure the distance between the four marks on the head of the molybdenum electrode and the four marks on the end of the ceramic tube that match. A wedge-shaped wooden block is used to adjust the gap between the first ceramic tube and the molybdenum electrode so that the center of the molybdenum electrode is aligned with the center of the ceramic tube.

[0010] Furthermore, in step one, after the molybdenum electrode and its auxiliary components are assembled as a whole, they are stored in the lava furnace shell and cured in a sealed manner using an electrolytic heating tube. The curing time is 24 hours at a temperature above 20°C.

[0011] Furthermore, in step one, when filling the gap between the molybdenum electrode and the first ceramic tube, after filling to the upper edge of the top insulating strip of the molybdenum electrode, pause for a while to allow a slight settling before continuing to fill.

[0012] Furthermore, in step two, when assembling and installing the molybdenum electrode, the thickness of the dense alumina castable is not less than 5 mm.

[0013] Furthermore, in step two, after the molybdenum electrode and surrounding supporting tiles are installed, the mortar around the molybdenum electrode is cured by lighting a furnace at a temperature above 20°C for 24 hours.

[0014] According to the continuous refining furnace molybdenum electrode installation method provided by the present invention, the molybdenum electrode and auxiliary components are first assembled, then the assembled molybdenum electrode is installed on the lower support tile, and finally the upper tile is installed. The gap filler material between the lower tile and the molybdenum electrode is replaced with dense alumina castable, avoiding rework caused by electrode sinking. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the molybdenum electrode installation according to the present invention; Figure 2 This is a schematic diagram showing the markings on the molybdenum electrode and the ceramic tube; Figure 3 This is a top view showing the position of the molybdenum electrode and the ceramic tube marking the wedge-shaped wooden block; Figure 4 This is a structural diagram of various types of irregularly shaped bricks supporting molybdenum electrodes.

[0016] In the figure, 1-molybdenum electrode, 2-ceramic tube, 3-wedge-shaped wooden block, 4-marked area of ​​molybdenum electrode, 5-marked area of ​​ceramic tube, 6-gap between ceramic tube and molybdenum electrode, 1a-inner edge of molybdenum electrode, 1b-outer edge of molybdenum electrode, 2a-inner edge of ceramic tube, 2b-outer edge of ceramic tube. Detailed Implementation

[0017] The present invention provides a method for installing molybdenum electrodes in a continuous refining furnace according to a typical embodiment. The molybdenum electrode 1 has a head of molybdenum (density 10.2 g / cm³), a middle part of stainless steel (density 7.93 g / cm³), and a tail of aluminum (density 2.7 g / cm³). The whole is composed of three different materials, and from the structural composition, the molybdenum electrode 1 is top-heavy and bottom-light.

[0018] The installation of molybdenum electrode 1 is the most crucial step in the construction of the continuous refining furnace. Once the furnace reaches the designed height, the installation of the molybdenum electrode support bricks begins. Each molybdenum electrode support consists of eight bricks of six different types. Their names, specifications, and structures are as follows: Figure 4 As shown.

[0019] The installation of molybdenum electrode 1 is divided into two parts: the assembly of molybdenum electrode 1 with its auxiliary components and the installation of the supporting tiles. First, the molybdenum electrode 1 is assembled with its auxiliary components. Then, the assembled molybdenum electrode 1 is installed on the lower supporting tile. Finally, the upper supporting tile is installed.

[0020] like Figure 1 As shown, the auxiliary components of the molybdenum electrode 1 include an isolation layer (0.3mm hot melt adhesive tape) and ceramic tubes 2 (513198A, 513198B). The support tiles are divided into lower tiles (513195, 513196, 513034) and upper tiles (513195, 513196, 513035).

[0021] 1. Assembly of molybdenum electrode 1 and auxiliary components 1.1 Construction of Molybdenum Electrode Insulation Layer Place molybdenum electrode 1 upright on a wooden platform 750mm high. Wrap molybdenum electrode 1 evenly with hot melt adhesive tape 50mm wide and 0.3mm thick. During the wrapping process, one person holds molybdenum electrode 1 to ensure it does not shake, while another person smooths the hot melt adhesive tape with both hands and wraps it slowly and evenly to ensure that the hot melt adhesive tape does not overlap and is tied in a knot. This ensures that after the continuous refining furnace is started, the hot melt adhesive tape will melt without large gaps.

[0022] 1.2 Construction of molybdenum electrode 1 and ceramic tube 513198A (1) Assembly of molybdenum electrode 1 and ceramic tube 513198A First, construct a precision-machined wooden assembly platform (500*500*750mm) with a level deviation of ±1mm. Place the molybdenum electrode 1, wrapped with an insulating layer, head down on the assembly platform. Next, evenly mark four points along the circumference of both the head of the molybdenum electrode 1 and the end of the ceramic tube 2 with a marker. Then, insert the 513198A ceramic tube into the neck of the molybdenum electrode 1, rotating the 513198A ceramic tube until the four marks on the molybdenum electrode 1 align with the four marks on the 513198A ceramic tube.

[0023] (2) Adjustment of the assembly gap between molybdenum electrode 1 and ceramic tube 513198A The distance between the four marks on the head of molybdenum electrode 1 and the four marks on the end of the 513198A ceramic tube were measured using a steel ruler. The distance between each group was 12.5 mm (e.g., ...). Figure 2 (As shown).

[0024] Four wedge-shaped wooden blocks 3 were used to adjust the detection data to ensure that the center of the molybdenum electrode 1 was aligned with the center of the ceramic tube 2 (e.g., Figure 3 (As shown).

[0025] (3) Filling the gap between the molybdenum electrode 1 and the ceramic tube 513198A After the 5mm gap between the ceramic tube 513198A and the molybdenum electrode 1 is adjusted to be within acceptable limits, it is fixed using adjusting wedge-shaped wooden blocks 3. Then, acid-resistant mortar is poured. The acid-resistant mortar is prepared according to a volume ratio of potassium silicate and Stellakitt KG powder of 1:3.6 to ensure good workability. Mortar is poured from the end of the 513198A ceramic tube to fill the gaps, filling up to the upper edge of the top adhesive tape. A slight settling will occur after a pause, and the filling will continue. After the mortar reaches a certain strength, the wooden blocks are removed.

[0026] 1.3 Assembly of molybdenum electrode 1 and ceramic tube 513198B After ceramic tube 513198A is installed, ceramic tube 513198B is installed next, using the same method as ceramic tube 513198A. The only difference is the reference position of the markings. Ceramic tube 513198A is installed with the mark on the head of molybdenum electrode 1 as the reference, while ceramic tube 513198B is installed with ceramic tube 513198A as the reference.

[0027] After assembly, the entire assembly is stored inside the lava furnace shell and cured in a sealed environment using 380V electrolytic heating tubes, ensuring a curing time of 24 hours at a temperature above 20℃. This improves the mortar strength and ensures there are no cracks between the ceramic tube and molybdenum electrode 1. Cracks are then non-destructively tested using an ultrasonic detector; those meeting the standard are classified as Level II, while those failing are recast.

[0028] 2. Supporting tiles and assembling molybdenum electrode installation 2.1 Installation of lower tiles (irregularly shaped bricks 513034, 513195, 513196) Before installing the electrode foundation brick 513034, use the assembled molybdenum electrode 1 to check the gap between the paired irregular bricks 513035 and 513034 after installation. Use a 100B20S feeler gauge for inspection. If the gap is greater than 3mm, the brick cannot be used and needs to be replaced. If the gap is less than 2mm, the brick needs to be precision machined to ensure the gap after installation is between 2-3mm. Simultaneously, check the installation position, elevation (EL-2405mm), and levelness (0.1mm / m) of the irregular brick 513034 in the continuous refining furnace. The installation length of the foundation brick 513034 must be equal to the length of the three supporting bricks; any excess can be adjusted by cutting the foundation bricks. For gaps ≤3mm, fill with mortar; for gaps >3mm, fill with Type I magnesium oxide ramming mix.

[0029] The height of the support surface beneath the foundation bricks is measured. Based on the opening position of the steel furnace body, the support surface of the foundation bricks is inspected and adjusted. After passing the inspection, high-alumina mortar is applied, and shaped brick 513034 is installed. The installation method for shaped bricks 513195 and 513196 is the same as for 513034. However, because shaped bricks 513195 and 513196 are made of different materials than shaped brick 513034, the adhesive material is different; ultra-high alumina mortar is used for the adhesive.

[0030] 2.2 Assembling and Installing Molybdenum Electrodes After the lower tile is installed, apply a dense alumina castable mortar, matching the material of the irregularly shaped brick, to the inner wall of the lower tile according to the design requirements, with a thickness of not less than 5mm. Then place the assembled molybdenum electrode 1 on the support tile and gently press to ensure a tight fit.

[0031] The space between the lower tile and the molybdenum electrode 1 is filled with dense alumina castable instead of ultra-high alumina mortar. To better ensure the pressure-bearing capacity, a certain amount of refractory particles are added. Specifically, the dense alumina castable mentioned in this invention uses products from Luoyang Jia'an Refractory Materials Co., Ltd., with 2% refractory particles added (MgO ≥ 98%, Al2O3 0.3%, SiO2 0.7%, Fe2O3 0.2%, CaO 0.7%).

[0032] Due to the high water content in the standard mix of ultra-high alumina mortar, coupled with the fact that the ambient temperature in Qinghai in December is below -10℃, even with the use of stoves and blankets for insulation at the construction site, the ambient temperature could only reach 15℃. This prevented the ultra-high alumina mortar between the lower tile and molybdenum electrode 1 from solidifying in time, resulting in insufficient load-bearing capacity to support the 186kg molybdenum electrode 1. Furthermore, during installation, slight compression was required for a tight fit, causing some ultra-high alumina mortar to be squeezed out of the supporting tile, leading to the sinking of molybdenum electrode 1. Uneven mortar joints appeared between molybdenum electrode 1 and the upper and lower tiles, with excessively wide gaps at the top and insufficiently narrow gaps at the bottom.

[0033] On-site simulation tests revealed that the gap between the upper tiles of the molybdenum electrode made of ultra-high alumina mortar was 6mm, and a thin iron wire could be inserted into the furnace body through the gap. The gap between the upper and lower tiles was 1.5mm. In contrast, the gap between the upper tiles of the molybdenum electrode made of dense alumina castable was 3.8mm, and a thin iron wire was extremely difficult to insert into the furnace body through the gap. The gap between the upper and lower tiles was 3.3mm.

[0034] 2.3 Installation of roof tiles (irregularly shaped bricks 513035, 513195, 513196) After confirming that the molybdenum electrode 1 is installed correctly, apply ultra-high alumina mortar to its exposed surface. At the same time, apply ultra-high alumina mortar to the inner walls of the irregularly shaped bricks 513035, 513195, and 513196, ensuring a tight fit. Finally, place the upper tiles in their respective positions.

[0035] During construction, when the ambient temperature is below 0℃ in winter, after the molybdenum electrode 1 and the surrounding bricks are laid and installed, a furnace is used to cure the mortar around the molybdenum electrode 1 to ensure the strength of the mortar. A dedicated person uses a TM-1310 thermometer to detect the temperature and ensure that the temperature is above 20℃. The wall bricks above the molybdenum electrode 1 are laid only after the curing time is 24 hours.

Claims

1. A method for installing molybdenum electrodes in a continuous refining furnace, characterized in that, Includes the following steps: Step 1: Assemble the molybdenum electrode and its auxiliary components, including: (1) Construction of the molybdenum electrode isolation layer; The molybdenum electrode isolation layer is hot melt adhesive tape, and the molybdenum electrode is evenly wrapped with hot melt adhesive tape once. (2) Construction of molybdenum electrode and ceramic tube; Place the molybdenum electrode head-down on the assembly platform, with the insulating layer wrapped around it. Mark four points evenly spaced around the circumference of both the molybdenum electrode head and the end of the first ceramic tube. Then, insert the first ceramic tube into the neck of the molybdenum electrode, rotating the tube to align the four marks on the molybdenum electrode with the four marks on the first ceramic tube. After adjusting the gap between the first ceramic tube and the molybdenum electrode to the correct level, secure it with wedge-shaped wooden blocks. Then, pour acid-resistant fire mortar from the end of the first ceramic tube to fill the gap between the molybdenum electrode and the first ceramic tube. Install the second ceramic tube behind the molybdenum electrode, using the first ceramic tube as a reference. Step two, supporting the tile and assembling the molybdenum electrode installation, includes: (1) Installation of the lower tile block; Measure the height of the support surface under the foundation bricks, check and adjust the support surface of the foundation bricks according to the opening position of the steel furnace body, and after the inspection is qualified, apply high-alumina mortar to the support surface under the foundation bricks and install the lower tiles. (2) Assemble and install the molybdenum electrode; After the lower tile is installed, apply a dense alumina casting material to the inner wall of the lower tile, then place the assembled molybdenum electrode on the lower tile and press it to ensure that they fit tightly together. (3) Install the roof tiles; After confirming that the molybdenum electrode is installed correctly, apply ultra-high alumina mortar to its exposed surface. At the same time, apply ultra-high alumina mortar to the inner wall of the upper tile. After placing the upper tile in the corresponding position, press it to make them fit tightly together.

2. The method for installing molybdenum electrodes in a continuous refining furnace according to claim 1, characterized in that: In step one, when constructing the molybdenum electrode isolation layer, the molybdenum electrode is placed upright on a wooden platform, and hot melt adhesive tape is used to evenly wrap the molybdenum electrode once. During the wrapping process, one person holds the molybdenum electrode to ensure it does not shake, while another person smooths the hot melt adhesive tape with both hands and wraps it slowly and evenly.

3. The method for installing molybdenum electrodes in a continuous refining furnace according to claim 1 or 2, characterized in that: The isolation layer uses hot melt adhesive tape that is 50mm wide and 0.3mm thick.

4. The method for installing molybdenum electrodes in a continuous refining furnace according to claim 3, characterized in that: In step one, after the molybdenum electrode and ceramic tube are installed, a steel ruler is used to measure the distance between the four marks on the head of the molybdenum electrode and the four marks on the end of the ceramic tube that match. Wedge-shaped wooden blocks are used to adjust the gap between the first ceramic tube and the molybdenum electrode so that the center of the molybdenum electrode is aligned with the center of the ceramic tube.

5. The method for installing molybdenum electrodes in a continuous refining furnace according to claim 1 or 4, characterized in that: In step one, after the molybdenum electrode and its auxiliary components are assembled, they are stored in the lava furnace shell and cured in a sealed manner using an electrolytic heating tube. The curing time is 24 hours at a temperature above 20°C.

6. The method for installing molybdenum electrodes in a continuous refining furnace according to claim 5, characterized in that: In step one, when filling the gap between the molybdenum electrode and the first ceramic tube, after filling to the upper edge of the top insulating strip of the molybdenum electrode, pause for a while until a little sedimentation occurs, and then continue filling.

7. The method for installing molybdenum electrodes in a continuous refining furnace according to claim 1 or 6, characterized in that: In step two, when assembling and installing the molybdenum electrode, the thickness of the dense alumina castable should not be less than 5 mm.

8. The method for installing molybdenum electrodes in a continuous refining furnace according to claim 7, characterized in that: In step two, after the molybdenum electrode and surrounding supporting tiles are installed, the mortar around the molybdenum electrode is cured by lighting a furnace at a temperature above 20°C for 24 hours.

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