Integrated device for hot dipping of aluminum-silicon coating and removal of iron-containing compound suspended slag

Abstract

The invention provides an integrated device for hot dipping of an aluminum-silicon coating and removal of iron-containing compound suspended slag. The device comprises a smelting furnace hearth system, a heater system, a temperature control system, a safety protection system and a power supply system. The device and the method are suitable for industrial hot-dip aluminum-silicon coating plating of steel, and impurities molten in an aluminum-silicon hot-dip plating solution in the steel are removed. The process device is simple in equipment, small in occupied area and wide in application range, the use efficiency of the melt can be improved, the factory cost is saved, the coating quality is improved, the steel performance is improved, and therefore the production benefit is improved.

Description

Technical Field

[0001] The present invention relates to an integrated device for hot-dip aluminized silicon coating and removal of iron-containing compound suspended slag, belonging to the technical fields of hot-dip coating technology and metal treatment technology. As a new anti-corrosion measure, hot-dip aluminized silicon alloy is widely used in industries such as the automotive manufacturing industry, construction industry, household appliance industry, and machinery manufacturing industry. It can maintain the beauty and excellent performance of steel for a long time, has excellent corrosion resistance, can effectively extend the service life of equipment and reduce maintenance costs. Background Art

[0002] The technology of hot-dip aluminized silicon steel is an advanced metal surface treatment technology developed in recent years. At a certain temperature, the steel is immersed in the molten aluminized silicon alloy for a certain time of hot-dip coating, so that the steel has excellent heat resistance, corrosion resistance, and high-temperature oxidation resistance.

[0003] However, during the hot-dip coating process, a large amount of slag will be generated. The existence of slag will pollute the melt, affect the coating quality, degrade the product quality, cause waste of metal resources, and increase the production cost of the industry. The slag generated in the molten pool can be divided into two categories: aluminum oxide dross and iron-containing compound suspended slag. Aluminum oxide dross is due to the high melting point of aluminum, and it is difficult to hot-dip aluminize steel. A large amount of melt will be oxidized during the dipping process, and a large amount of aluminum slag will be generated in the aluminum pot, which is likely to cause defects such as aluminum slag on the surface of the steel. Aluminum slag defects are the main reason for product degradation. The iron-containing compound suspended slag is due to the strong affinity between aluminum and iron, which causes the steel to react violently with elements such as aluminum in the melt, forming iron-aluminum or iron-aluminum-silicon and other iron-containing compound suspended slag, resulting in an increase in the accumulation of slag generated in the molten pool. According to the different densities of aluminum oxide dross and iron-containing compound suspended slag, they can be divided into dross and bottom slag. The density of aluminum oxide dross is relatively small and floats on the surface of the molten pool, and it can be easily removed by tools during the production process; the iron-containing compound suspended slag with a large density accumulates and grows in the pool and is easily deposited at the bottom of the molten pool to form bottom slag. Currently, the bottom slag is removed by stopping the machine and salvaging during production. However, in the molten pool, due to the similar density of the initially formed aluminum slag and the melt density, it will be suspended in the molten pool under the agitation of electromagnetic heating to form suspended slag.

[0004] At present, the patent number is CN202311615523.2. Through the continuous operation of blowing, collecting, and discharging, the oxide dross of aluminum is removed, avoiding the dross from easily adhering to the strip during the production of hot-dip coated strip steel. However, this method is only used for the dross removal of hot-dip coating. In addition, for removing the iron-containing compound suspension dross, multiple melting pools are also used in industrial production. After the hot-dip aluminosilicon process is carried out on the steel in one melting pool and a certain amount of bottom dross is generated, the hot-dip melt is transferred to another melting furnace for static precipitation. After the iron-containing compound suspension dross has settled, the melt is recycled. This method has a large floor area, increases industrial production costs, and is difficult to control the temperature during the melt transfer process.

[0005] Therefore, in order to skim the oxide dross of aluminum that floats during the hot-dip process and scoop up the iron-containing compound suspension dross that sinks, an integrated device for hot-dip aluminosilicon coating and removal of iron-containing compound suspension dross is designed, aiming to optimize the coating quality, improve the dross removal efficiency, and ensure process stability and material utilization rate. Summary of the Invention

[0006] Aiming at the deficiencies of the existing dross removal technology, the present invention provides an integrated device for hot-dip aluminosilicon coating and removal of iron-containing compound suspension dross to settle the suspension dross in the melting pool and effectively remove the dross.

[0007] The present invention provides an integrated device for hot-dip aluminosilicon coating and removal of iron-containing compound suspension dross. Through the heater system, the temperatures of the upper, middle, and lower zones are set respectively. The resistance heating controller and the electromagnetic heating controller are started to heat the aluminum-silicon alloy in the furnace chamber. After reaching the appropriate hot-dip temperature and the melt is melted, the electromagnetic heating controller is turned off, and then the pre-treated steel can be hot-dip aluminosilicon coated in the upper zone to form a dense coating that is highly efficient, durable, and has strong corrosion resistance. The aluminum-iron-silicon metal compound generated when the steel is hot-dip coated and the melt, under the action of the gravity field and temperature gradient, passes through the middle zone and finally settles to the lower zone, achieving the purpose of settling the iron-containing compound suspension dross. Subsequently, slag skimming tools (such as slag rakes) are used to skim the dross from the surface of the melt, and slag scooping tools (such as slag spoons) are used to scoop up the bottom dross from the melt. The technical solutions adopted are as follows:

[0008] An integrated device for hot-dip aluminosilicon coating and removal of iron-containing compound suspension dross includes a melting furnace chamber system, a heater system, a temperature control system, a safety protection system, and a power supply system.

[0009] The melting furnace chamber system includes a furnace lining, refractory bricks, and asbestos. The melting furnace chamber system is designed as a cylindrical furnace chamber, and the contact between the inner wall and the bottom of the furnace chamber is designed as a rounded corner. The intermediate layer is located between the refractory bricks and asbestos of the furnace chamber, forming an intermediate space. The furnace lining is in direct contact with the molten metal (melt), and the refractory bricks are connected to the furnace lining.

[0010] The described heater system consists of an electromagnetic heating controller, a resistance heating controller, an electromagnetic induction coil, a resistance coil, etc., and is designed to form a composite heating with two heating elements, namely electromagnetic induction heating and resistance heating. Before hot-dip aluminizing silicon on steel, both electromagnetic induction heating and resistance heating modes are started simultaneously. By using the additional stirring effect of the alternating magnetic field on the melt in electromagnetic induction heating, the temperature and composition within each layer are made uniform respectively. When hot-dip aluminizing silicon on steel, electromagnetic induction heating is turned off, and resistance heating is used for heating and heat preservation to avoid the influence of the additional stirring of the alternating magnetic field on the melt on the sedimentation of the slag. Different numbers of turns are set in three layers to achieve three temperature zones with gradually decreasing temperatures, so that the slag accelerates sedimentation under the action of the gravitational field and temperature field. The described electromagnetic induction coil and resistance coil are wrapped outside the refractory bricks of the melting furnace hearth system, and a magnetic yoke is wrapped outside the electromagnetic induction coil and resistance coil to restrain the leakage magnetic field of the heating coil from diffusing outward and improve the efficiency of induction heating.

[0011] The described temperature control system includes components such as temperature sensors and a controller. The temperature control system monitors the temperatures of the upper, middle, and lower three temperature zones in real time through three temperature sensors. When the temperature deviates from the preset value, the controller will issue a control command to achieve the temperature adjustment function and keep the temperature within the set range. The described temperature control system is connected to the electromagnetic heating controller and the resistance heating controller.

[0012] The described safety protection system monitors the temperatures of each zone of the melting furnace hearth system, as well as the current and circuit status in real time. Once an abnormality is detected, such as too high temperature, too large current, or circuit failure, the system will immediately trigger the alarm mechanism and cut off the power supply through the controller to prevent potential safety hazards. At the same time, the safety protection system also has a fault self-diagnosis function, which can accurately identify and report the type of fault, facilitating maintenance personnel to quickly locate and solve the problem, and ensuring the smooth progress of the hot-dip aluminizing silicon process and the safe operation of the equipment.

[0013] The described power supply system serves as the main power supply to provide electrical energy for the melting furnace hearth system, the heater system, the temperature control system, and the safety protection system.

[0014] Based on the above technical solution, in the heater system, different numbers of turns of electromagnetic and resistance coils are set in the upper, middle, and lower zones to form three temperature zones with gradually decreasing temperatures: the upper temperature zone, the middle temperature zone, and the lower temperature zone; and the relationship between the temperature T1 in the upper temperature zone, the temperature T2 in the middle temperature zone, and the temperature T3 in the lower temperature zone is: T1 > T2 > T3 > the melting point of aluminum-silicon alloy. Due to the fact that the specific gravity of iron-containing aluminum-iron-silicon intermetallic compounds is higher than that of the aluminum-silicon melt, a segregation phenomenon occurs. Under the action of the temperature gradient and the gravitational field, the aluminum-iron-silicon intermetallic compounds continuously sink, from the upper zone → the middle zone → the lower zone, and under the temperature gradient of T1 > T2 > T3, the iron-containing compound suspension slag sinks, while the alumina floating slag floats up.

[0015] Based on the above technical solution, in the temperature control system, temperature sensors are respectively set in the upper, middle, and lower zones to detect the temperatures in the molten pools in the upper, middle, and lower zones, ensuring accurate control of the hot-dip plating process temperature.

[0016] Based on the above technical solution, in the heater system, the electromagnetic induction heating controller can be turned off to remove the stirring effect of electromagnetic induction heating on the melt, enabling the slag in the melt to settle.

[0017] Based on the above technical solution, in the safety protection system, a protection switch is set at the temperature control system. By monitoring the temperatures in each zone of the melting furnace hearth system through the temperature control system, when the temperature deviates from the set range, the protection switch in the safety protection system will be triggered to disconnect, preventing equipment damage or safety accidents.

[0018] The present invention has the following advantages: The composite heating formed by the electromagnetic induction heating and the resistance heating makes the components and temperatures in each zone of the melting furnace hearth system uniform, with a fast melting speed; compared with adding a low-temperature static melting furnace hearth system on the side of the melting furnace hearth system for slag removal, the device of the present invention is simple, occupies a small area, and saves factory costs; the slag removal effect is remarkable, avoiding pollution of the melt, affecting the coating quality, improving the reusability of the melt, and reducing the waste of metal resources; a safety protection system is set to ensure the safe operation of the melting furnace hearth system, preventing safety accidents such as equipment damage, production interruption, and even fire caused by abnormal situations. Description of the Drawings

[0019] Figure 1 Device diagram of the present invention

[0020] Figure 2 Device diagram of the melting furnace hearth system of the present invention

[0021] Figure 3 Production process flow chart of the present invention

[0022] The description of the reference numerals is as follows:

[0023] Electromagnetic induction coil (inlet) 1; Electromagnetic induction coil (outlet) 2; Resistance coil (inlet) 3; Resistance coil (outlet) 4; Temperature sensor 5; Heat-resistant rotor 6; Furnace lining 7; Aluminum oxide scum 8; Iron-containing compound suspended slag 9; Magnetic yoke 10; Asbestos 11. Detailed implementation

[0024] Implementation case one:

[0025] 1. Hot-dip plating preparation: Add a certain content of aluminum-silicon alloy into the furnace chamber. The composition of the aluminum-silicon alloy is silicon 8.5% - 10.0%, iron 1.5% - 3.0%, and the rest is aluminum.

[0026] 2. Heating system configuration: The furnace chamber has three independent heating zones. The upper zone is equipped with high-power resistance heaters and electromagnetic heaters; the middle zone is equipped with medium-power resistance heaters and electromagnetic heaters; the lower zone is equipped with low-power resistance heaters and electromagnetic heaters.

[0027] 3. Temperature control: Start the resistance heating controller and the electromagnetic heating controller, and monitor the temperatures of the upper, middle, and lower zones in real time through sensors. The temperature of the molten pool quickly reaches the set temperature, ensuring T1 = 750 °C, T2 = 650 °C, T3 = 590 °C, and the temperature of each zone is uniform. At the same time, the temperature of all zones is higher than the eutectic point of the aluminum-silicon alloy (577 °C) to ensure that the aluminum-silicon alloy in the molten pool is completely melted.

[0028] 4. Steel pretreatment: Conduct alkaline cleaning pretreatment on the surface of the steel to remove rust, impurities, mill scale, and oil stains on the surface, etc., to ensure the surface is clean, which is conducive to the mutual diffusion of Fe atoms on the substrate surface and the plating alloy to form a stable transition layer.

[0029] 5. Heat preservation and hot-dip plating: After the temperature and composition in the molten pool are uniform, turn off the electromagnetic heating system, and only use the resistance heating system for heat preservation to carry out the hot-dip aluminum-silicon process for the steel.

[0030] 6. Slag removal: Regularly fish out the bottom slag of iron-containing compounds and scrape off the aluminum oxide scum.

[0031] Implementation case two:

[0032] 1. Hot-dip plating preparation: Add a certain content of aluminum-silicon alloy into the furnace chamber. The composition of the aluminum-silicon alloy is silicon 17.0% - 20.0%, iron 1.5% - 3.0%, and the rest is aluminum.

[0033] 2. Heating system configuration: The furnace chamber has three independent heating zones. The upper zone is equipped with high-power resistance heaters and electromagnetic heaters; the middle zone is equipped with medium-power resistance heaters and electromagnetic heaters; the lower zone is equipped with low-power resistance heaters and electromagnetic heaters.

[0034] 3. Temperature control: Start the resistance heating controller and the electromagnetic heating controller. Monitor the temperatures of the upper, middle, and lower zones in real time through sensors. The temperature of the molten pool quickly reaches the set temperature, ensuring that T1 = 800 °C, T2 = 750 °C, T3 = 700 °C and the temperatures of each zone are uniform. At the same time, the temperatures of all zones are higher than the eutectic point of the aluminum-silicon alloy, ensuring that the aluminum-silicon alloy in the molten pool is completely melted.

[0035] 4. Steel pretreatment: Conduct alkaline washing pretreatment on the steel surface to remove rust, impurities, mill scale, oil stains, etc. on the surface, ensuring a clean surface to facilitate the mutual diffusion of Fe atoms on the substrate surface and the coating alloy to form a stable transition layer.

[0036] 5. Heat preservation and hot dip aluminizing: After the temperature and composition in the molten pool are uniform, turn off the electromagnetic heating system and only use the resistance heating system for heat preservation to perform the hot dip aluminizing process on the steel.

[0037] 6. Slag removal: Regularly fish out the bottom slag containing iron compounds and skim off the floating slag of aluminum oxides.

Claims

1. An integrated device for hot-dip aluminum-silicon coating and removal of suspended slag containing iron compounds, characterized in that include: Melting furnace hearth system, heater system, temperature control system, safety protection system, and power supply system.

2. An integrated device for hot-dip aluminum-silicon coating and removal of suspended slag containing iron compounds, characterized in that: The heater system described in claim 1 is a composite heater system composed of two heating bodies, electromagnetic induction heating and resistance heating. The electromagnetic induction coil and the resistance coil are alternately wound in the middle layer of the smelting furnace system, and electromagnetic induction coils and resistance coils with different numbers of turns are arranged in three layers from top to bottom, thereby forming three temperature zones: upper, middle and lower.

3. An integrated device for hot-dip aluminum-silicon coating and removal of suspended slag containing iron compounds, characterized in that: The upper temperature zone described in claim 2 is subjected to hot-dip coating process to ensure good bonding between the aluminum silicon coating and the steel.

4. An integrated device for hot-dip aluminum-silicon coating and removal of suspended slag containing iron compounds, characterized in that: The temperatures of the upper, middle and lower temperature zones described in claim 2 decrease in sequence, and the temperature characteristics of each temperature zone are: the upper temperature zone is greater than the middle temperature zone, the middle temperature zone is greater than the lower temperature zone, and the lower temperature zone is greater than the melting point of the aluminum-silicon alloy.

5. An integrated device for hot-dip aluminum-silicon coating and removal of suspended slag containing iron compounds, characterized in that: The temperatures at the junctions of the upper, middle and lower temperature zones described in claim 3 are continuously distributed.

6. An integrated device for hot-dip aluminum-silicon coating and removal of suspended slag containing iron compounds, characterized in that: The temperature of the three temperature zones is controlled by a temperature control system to form different temperature gradients, thereby controlling the thickness of the hot-dip aluminum-silicon coating and the efficiency of the settling of the iron-containing compound suspended slag.

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