A method for hot-dip galvanizing an angle steel

Abstract

The application discloses a kind of angle steel hot galvanizing method, first high-pressure water washing rust removal: angle steel is transferred to washing area by travelling crane;The application patent is by using first high-pressure and removes the rust block on the surface of angle steel, and the angle steel is pickled by composite rust removal solvent, the dithiocarbamate in composite rust removal solvent can remove the oil stain on angle steel, has the corrosion inhibition effect and can replace the corrosion inhibition use, using TX-10 can activate and penetrate angle steel, using sodium dodecyl sulfate can wet and penetrate angle steel, it also has the effect of inhibiting acid mist to angle steel, the method has good derusting effect, no rust spot is left, and pickling speed is fast, the phenomenon that mud slag is generated by over-pickling does not occur, and most of iron salt and oxide can be removed by using warm water flushing after that, the salt film deposited after angle steel pickling is complete and uniform, there is no leak point salt film discontinuous mood, there is no plating, virtual plating, plating zinc adhesion problem after galvanizing, improve the quality, efficiency of angle steel galvanizing.

Description

Technical Field

[0001] This invention relates to the field of hot-dip galvanizing technology, specifically to a method for hot-dip galvanizing angle steel. Background Technology

[0002] Optimized hot-dip galvanizing processes refer to making the process more rational and scientific. The aim is to improve the surface quality of angle steel, reduce the generation of iron and other impurities that affect zinc consumption, control the occurrence of defective products, and lower galvanizing costs. To ensure the adhesion of hot-dip galvanized angle steel, pickling is an essential pre-processing step. Currently, angle steel is pickled with a single hydrochloric acid or sulfuric acid solution before hot-dip galvanizing. The adhesion of angle steel during hot-dip galvanizing is affected by pickling; pickling with a single hydrochloric acid or sulfuric acid solution is insufficient to completely clean the angle steel surface, leaving residual rust. When the angle steel enters the molten zinc, the rust hinders the reaction between the steel substrate and zinc to form a zinc-iron alloy layer, resulting in uncoated spots (patches) and requiring rework. Excessive pickling with a single hydrochloric acid or sulfuric acid solution produces highly adhesive sludge that is difficult to remove from the steel surface.

[0003] To address this problem, a hot-dip galvanizing method for angle steel is proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a hot-dip galvanizing method for angle steel, which solves the problems of incomplete pickling, excessive pickling time, and the formation of highly adhesive mud residue that is difficult to remove when using a single hydrochloric acid or sulfuric acid aqueous solution for pickling angle steel.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for hot-dip galvanizing angle steel, comprising the following steps:

[0006] Step 1: High-pressure water washing and rust removal: The angle steel is transferred to the water washing area by a gantry crane, and high-pressure water is sprayed onto the angle steel by a high-pressure water gun to wash away and peel off the impurities and some rust on the surface of the angle steel.

[0007] Step 2: Rust removal with compound rust remover: The angle steel is transferred to the pickling tank by a gantry crane and immersed in the pickling tank for pickling. The pickling time is 1-5 hours.

[0008] A composite rust-removing solvent is added to the pickling tank. The composite rust-removing agent includes 10-30 parts of surfactant, 10-20 parts of wetting agent, 10-40 parts of composite solvent and 30-60 parts of water.

[0009] The composite solvent is dithiocarbamate, the surfactant is TX-10, and the wetting agent is sodium dodecyl sulfate;

[0010] Step 3: Iron removal with composite flux: The angle steel is lifted by a crane and transferred to the water washing area for high-pressure rinsing again to dissolve the iron salts adhering to the angle steel and reduce the amount of iron salts carried into the next process. Warm water is used for rinsing.

[0011] After rinsing and drying, the angle steel is transported to the zinc plating bath by a crane. The angle steel is immersed in the zinc plating bath, where the flux removes iron from the angle steel and cleans the iron salts or oxides remaining on the surface of the angle steel. This ensures that the steel parts have maximum surface activity when entering the zinc bath and deposits a salt film on the surface of the angle steel. After drying, the steel parts proceed to the next step.

[0012] Step 4: Hot-dip galvanizing: The angle steel is transferred to the galvanizing tank by a crane and then immersed in the galvanizing tank for galvanizing.

[0013] Step 5: Water cooling: The angle steel that has finished dripping excess galvanizing liquid is transferred to the cooling pool by a crane, and the angle steel is immersed in the water in the cooling pool for cooling.

[0014] Step 6: Passivation: The cooled angle steel is transferred to the passivation tank by a crane and immersed in the passivation tank for passivation.

[0015] Step 7: Inspection and Packaging: The angle steel is transferred to the inspection area by a crane to check whether it is qualified, and then it is packaged and put into storage.

[0016] Preferably, in step 1, during the pickling process, the rust on the surface of the angle steel is corroded and separated from the surface of the angle steel, and the oil on the surface of the angle steel is corroded and separated from the angle steel.

[0017] Preferably, in step 2, the temperature of the warm water is at least greater than 35°C.

[0018] Preferably, in step 2, the flux is mainly one of ammonium chloride or zinc chloride composite aqueous solution.

[0019] Preferably, in step 3, during the process of lowering the angle steel into the galvanizing bath by a gantry crane, the gantry crane first lowers one end of the angle steel into the galvanizing bath and contacts the zinc plating solution, keeping it stationary. Then, the gantry crane continuously lowers the other end of the angle steel into the galvanizing bath at a decreasing angle until both ends of the angle steel are at the same horizontal level in the galvanizing bath.

[0020] Preferably, in step 3, during the lifting process of the angle steel by the gantry crane, the gantry crane lifts one end of the angle steel first, and then lifts the other end of the angle steel, so that the two ends of the angle steel are at an angle of not less than 60°, and waits for the excess zinc plating liquid on the surface of the angle steel to drip off with the tilt angle of the angle steel.

[0021] Preferably, in step 3, the water in the cooling pool, after reaching 35°C, can be introduced into step 3 as warm water for rinsing iron salts; if the temperature exceeds 60°C, cold water is added to assist in controlling the temperature between 35-60°C.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] This invention patent employs a method that first removes rust from the surface of angle steel under high pressure, followed by pickling of the angle steel with a composite rust-removing solvent. The composite solvent contains dithiocarbamate, which removes oil stains from the angle steel and acts as a corrosion inhibitor, replacing traditional corrosion inhibitors. TX-10 activates and penetrates the angle steel, while sodium dodecyl sulfate wets and penetrates it, also inhibiting acid mist. This method achieves excellent rust removal, leaves no rust spots, and has a fast pickling speed, avoiding over-pickling and the formation of sludge. A warm water rinse removes most iron salts and oxides, resulting in a complete and uniform salt film deposited on the angle steel after pickling, without any gaps or discontinuous salt film. This eliminates problems such as missed plating, incomplete plating, and insufficient zinc adhesion after galvanizing, thus improving the quality and efficiency of angle steel galvanizing. Detailed Implementation

[0024] The present invention will now be described in more detail by way of examples. These examples are merely illustrative and do not limit the scope of the present invention in any way.

[0025] This invention provides a technical solution: a method for hot-dip galvanizing angle steel, comprising the following steps:

[0026] Step 1: High-pressure water washing and rust removal: The angle steel is transferred to the water washing area by a gantry crane, and high-pressure water is sprayed onto the angle steel by a high-pressure water gun to wash away and peel off the impurities and some rust on the surface of the angle steel.

[0027] Step 2: Rust removal with compound rust remover: The angle steel is transferred to the pickling tank by a gantry crane and immersed in the pickling tank for pickling. The pickling time is 1-5 hours.

[0028] A composite rust-removing solvent is added to the pickling tank. The composite rust-removing agent includes 10-30 parts of surfactant, 10-20 parts of wetting agent, 10-40 parts of composite solvent and 30-60 parts of water.

[0029] The composite solvent is dithiocarbamate, the surfactant is TX-10, and the wetting agent is sodium dodecyl sulfate;

[0030] Step 3: Iron removal with composite flux: The angle steel is lifted by a crane and transferred to the water washing area for high-pressure rinsing again to dissolve the iron salts adhering to the angle steel and reduce the amount of iron salts carried into the next process. Warm water is used for rinsing.

[0031] After rinsing and drying, the angle steel is transported to the zinc plating bath by a crane. The angle steel is immersed in the zinc plating bath, where the flux removes iron from the angle steel and cleans the iron salts or oxides remaining on the surface of the angle steel. This ensures that the steel parts have maximum surface activity when entering the zinc bath and deposits a salt film on the surface of the angle steel. After drying, the steel parts proceed to the next step.

[0032] Step 4: Hot-dip galvanizing: The angle steel is transferred to the galvanizing tank by a crane and then immersed in the galvanizing tank for galvanizing.

[0033] Step 5: Water cooling: The angle steel that has finished dripping excess galvanizing liquid is transferred to the cooling pool by a crane, and the angle steel is immersed in the water in the cooling pool for cooling.

[0034] Step 6: Passivation: The cooled angle steel is transferred to the passivation tank by a crane and immersed in the passivation tank for passivation.

[0035] Step 7: Inspection and Packaging: The angle steel is transferred to the inspection area by a crane to check whether it is qualified, and then it is packaged and put into storage.

[0036] Example 1: High-pressure water washing for rust removal: The angle steel is transferred to the water washing area using an overhead crane. High-pressure water is sprayed onto the angle steel using a high-pressure water gun to wash away impurities and some rust from the surface. Composite rust remover for rust removal: The angle steel is transferred to the pickling tank using an overhead crane and immersed in the pickling tank for 1-5 hours. A composite rust remover solvent is added to the pickling tank. The composite rust remover includes 10-30 parts surfactant, 10-20 parts wetting agent, 10-40 parts composite solvent, and 30-60 parts water. The composite solvent is dithiocarbamate, the surfactant is TX-10, and the wetting agent is sodium dodecyl sulfate. Composite flux for iron removal: The angle steel is lifted by an overhead crane and transferred to the water washing area for another high-pressure wash to dissolve and remove adhering iron salts, reducing their introduction into the next process. The iron salts in the angle steel are rinsed with warm water. After rinsing and drying, the angle steel is transferred to the fluxing tank by overhead crane. The fluxing agent in the tank removes iron from the angle steel and cleans the iron salts or oxides remaining on the surface of the angle steel, so that the steel parts have maximum surface activity when entering the zinc bath and a salt film is deposited on the surface of the angle steel. After drying, the angle steel proceeds to the next step. Hot-dip galvanizing: The angle steel is transferred to the galvanizing tank by overhead crane and immersed in the galvanizing tank for galvanizing. Water cooling: The angle steel with excess galvanizing solution dripping off is transferred to the cooling tank by overhead crane and immersed in the water in the cooling tank for cooling. Passivation: The cooled angle steel is transferred to the passivation tank by overhead crane and immersed in the passivation tank for passivation. Inspection and packaging: The angle steel is transferred to the inspection area by overhead crane to inspect whether the angle steel is qualified, and then packaged and stored.

[0037] Example 2: In Example 1, the following steps are added:

[0038] In step 1, during the pickling process, the rust on the surface of the angle steel is corroded and separated from the surface of the angle steel, and the oil on the surface of the angle steel is corroded and separated from the angle steel.

[0039] High-pressure water washing for rust removal: Angle steel is transferred to the washing area using an overhead crane. High-pressure water is sprayed onto the angle steel using a high-pressure water gun to wash away impurities and some rust from the surface. During the pickling process, the rust on the angle steel surface is corroded and separated from the surface, and the oil on the angle steel surface is also corroded and separated from the surface. Composite rust remover for rust removal: Angle steel is transferred to the pickling tank using an overhead crane and immersed in the pickling tank for pickling for 1-5 hours. A composite rust remover solvent is added to the pickling tank. The composite rust remover includes 10-30 parts surfactant, 10-20 parts wetting agent, 10-40 parts composite solvent, and 30-60 parts water. The composite solvent is dithiocarbamate, the surfactant is TX-10, and the wetting agent is sodium dodecyl sulfate. Composite flux for iron removal: Angle steel is lifted by an overhead crane and transferred to the washing area for high-pressure washing again to wash away impurities and some rust from the surface. The process begins with dissolving adhering iron salts to reduce their introduction into the next process. Warm water is used for rinsing. After rinsing and drying, the angle steel is transported to the fluxing tank via an overhead crane. The fluxing agent in the tank removes iron from the angle steel and cleans any residual iron salts or oxides on its surface, maximizing surface activity when the steel parts enter the zinc bath and depositing a salt film. The steel is then dried before proceeding to the next step. Hot-dip galvanizing involves transferring the angle steel to the galvanizing tank via an overhead crane and immersing it in the tank for galvanizing. Water cooling involves transferring excess galvanizing solution from the angle steel to a cooling tank via an overhead crane and immersing it in the water for cooling. Passivation involves transferring the cooled angle steel to a passivation tank via an overhead crane and immersing it in the passivation tank for passivation. Finally, inspection and packaging involve transferring the angle steel to the inspection area via an overhead crane to check its quality before packaging and warehousing.

[0040] Example 3: In Example 2, the following steps are added:

[0041] In step 2, the temperature of the warm water is at least greater than 35°C, and the flux is mainly one of the aqueous solutions of ammonium chloride or zinc chloride.

[0042] High-pressure water washing for rust removal: Angle steel is transferred to the washing area using an overhead crane. High-pressure water is sprayed onto the angle steel using a high-pressure water gun to wash away impurities and some rust from the surface. During pickling, rust on the angle steel surface is corroded and separated from the surface, and oil stains on the angle steel surface are also corroded and separated from the surface. Composite rust remover for rust removal: Angle steel is transferred to the pickling tank using an overhead crane and immersed in the pickling tank for pickling for 1-5 hours. A composite rust remover is added to the pickling tank. The composite rust remover includes 10-30 parts surfactant, 10-20 parts wetting agent, 10-40 parts composite solvent, and 30-60 parts water. The composite solvent is dithiocarbamate, the surfactant is TX-10, and the wetting agent is sodium dodecyl sulfate. The warm water temperature is at least 35°C, and the flux is mainly one of ammonium chloride or zinc chloride composite aqueous solution. Composite flux for iron removal: Angle steel is lifted and transferred to the water tank using an overhead crane. The washing area undergoes another high-pressure rinse to dissolve and remove adhering iron salts from the angle steel, reducing the amount of iron salts carried into the next process. Warm water is used for rinsing. After rinsing and drying, the angle steel is transferred to the fluxing tank via an overhead crane. The fluxing agent in the tank removes iron from the angle steel and cleans any residual iron salts or oxides on its surface, maximizing surface activity when the steel parts enter the zinc bath and depositing a salt film on the surface. After drying, the angle steel proceeds to the next step: Hot-dip galvanizing: The angle steel is transferred to the galvanizing tank via an overhead crane and immersed in the galvanizing tank for galvanizing. Water cooling: The angle steel, after excess galvanizing solution has dripped, is transferred to the cooling tank via an overhead crane and immersed in the water for cooling. Passivation: The cooled angle steel is transferred to the passivation tank via an overhead crane and immersed in the passivation tank for passivation. Inspection and packaging: The angle steel is transferred to the inspection area via an overhead crane to check its quality before being packaged and stored.

[0043] Example 4: In Example 3, the following steps are added:

[0044] In step 3, during the process of lowering the angle steel into the galvanizing bath by a gantry crane, the gantry crane first lowers one end of the angle steel into the galvanizing bath and keeps it stationary. Then, the gantry crane gradually lowers the other end of the angle steel into the galvanizing bath until both ends of the angle steel are at the same horizontal level in the galvanizing bath. During the lifting process by the gantry crane, one end of the angle steel is lifted first, followed by the other end, and the two ends of the angle steel are kept at an angle of not less than 60°. Excess galvanizing liquid on the surface of the angle steel drips off with the angle of inclination of the angle steel. The water in the cooling tank, after reaching 35°C, can be introduced into step 3 as warm water for rinsing iron salts. If the temperature exceeds 60°C, cold water is added to assist in controlling the temperature between 35-60°C.

[0045] High-pressure water washing for rust removal: Angle steel is transferred to the washing area using an overhead crane. High-pressure water is sprayed onto the angle steel using a high-pressure water gun to wash away impurities and some rust from the surface. During the pickling process, the rust on the angle steel surface is corroded and separated from the surface, and the oil on the angle steel surface is also corroded and separated from the surface. Composite rust remover for rust removal: Angle steel is transferred to the pickling tank using an overhead crane and immersed in the pickling tank for pickling. The pickling time is 1-5 hours. A composite rust remover solvent is added to the pickling tank. The composite rust remover includes 10-30 parts of surfactant, 10-20 parts of wetting agent, 10-40 parts of composite solvent, and 30-60 parts of water. The composite solvent is dithiocarbamate, the surfactant is TX-10, and the wetting agent is sodium dodecyl sulfate. The warm water temperature is at least above 35°C. The flux is mainly one of ammonium chloride or zinc chloride composite aqueous solution. Iron removal using the composite flux: The angle steel is lifted by an overhead crane and transferred to the water washing area for high-pressure rinsing again to dissolve and remove adhering iron salts, reducing the amount of iron salts carried into the next process. Warm water is used for rinsing. During the process of lowering the angle steel into the galvanizing tank by the overhead crane, one end of the angle steel is first placed into the galvanizing tank and kept stationary while the other end is gradually lowered into the galvanizing tank at a decreasing angle. Until both ends of the angle steel are at the same level in the galvanizing bath, the angle steel is lifted by a gantry crane. The crane lifts one end of the angle steel first, followed by the other end, ensuring the two ends are at an angle of at least 60°. Excess galvanizing solution drips from the angle steel's surface following its tilt. Once the water in the cooling tank reaches 35°C, it can be used as warm water for rinsing off iron salts in step 3. If the temperature exceeds 60°C, cold water is added to maintain the temperature between 35-60°C. After rinsing and drying, the angle steel is transferred to the fluxing bath by the gantry crane. The angle steel is then immersed in the fluxing bath, where the flux removes iron and cleans the steel. The iron salts or oxides remaining on the surface of the angle steel give the steel parts maximum surface activity when entering the zinc bath, and a salt film is deposited on the surface of the angle steel. After drying, it enters the next step; hot-dip galvanizing: the angle steel is transferred to the galvanizing tank by a crane and immersed in the galvanizing tank for galvanizing; water cooling: the angle steel after excess galvanizing liquid dripping is transferred to the cooling tank by a crane and immersed in the water in the cooling tank for cooling; passivation: the cooled angle steel is transferred to the passivation tank by a crane and immersed in the passivation tank for passivation; inspection and packaging: the angle steel is transferred to the inspection area by a crane to check whether the angle steel is qualified, and then packaged and stored.

[0046] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for hot-dip galvanizing angle steel, characterized in that: Includes the following steps: Step 1: High-pressure water washing and rust removal: The angle steel is transferred to the water washing area by a gantry crane, and high-pressure water is sprayed onto the angle steel by a high-pressure water gun to wash away and peel off the impurities and some rust on the surface of the angle steel. Step 2: Rust removal with compound rust remover: The angle steel is transferred to the pickling tank by a gantry crane and immersed in the pickling tank for pickling. The pickling time is 1-5 hours. A composite rust-removing solvent is added to the pickling tank. The composite rust-removing agent includes 10-30 parts of surfactant, 10-20 parts of wetting agent, 10-40 parts of composite solvent and 30-60 parts of water. The composite solvent is dithiocarbamate, the surfactant is TX-10, and the wetting agent is sodium dodecyl sulfate; Step 3: Iron removal with composite flux: The angle steel is lifted by a crane and transferred to the water washing area for high-pressure rinsing again to dissolve the iron salts adhering to the angle steel and reduce the amount of iron salts carried into the next process. Warm water is used for rinsing. After rinsing and drying, the angle steel is transported to the zinc plating bath by a crane. The angle steel is immersed in the zinc plating bath, where the flux removes iron from the angle steel and cleans the iron salts or oxides remaining on the surface of the angle steel. This ensures that the steel parts have maximum surface activity when entering the zinc bath and deposits a salt film on the surface of the angle steel. After drying, the steel parts proceed to the next step. Step 4: Hot-dip galvanizing: The angle steel is transferred to the galvanizing tank by a crane and then immersed in the galvanizing tank for galvanizing. Step 5: Water cooling: The angle steel that has finished dripping excess galvanizing liquid is transferred to the cooling pool by a crane, and the angle steel is immersed in the water in the cooling pool for cooling. Step 6: Passivation: The cooled angle steel is transferred to the passivation tank by a crane and immersed in the passivation tank for passivation. Step 7: Inspection and Packaging: The angle steel is transferred to the inspection area by a crane to check whether it is qualified, and then it is packaged and put into storage.

2. The hot-dip galvanizing method for angle steel according to claim 1, characterized in that: In step 1, during the pickling process, the rust on the surface of the angle steel is corroded and separated from the surface of the angle steel, and the oil on the surface of the angle steel is corroded and separated from the angle steel.

3. The hot-dip galvanizing method for angle steel according to claim 1, characterized in that: In step 2, the temperature of the warm water is at least greater than 35°C.

4. The hot-dip galvanizing method for angle steel according to claim 1, characterized in that: In step 2, the flux is mainly one of ammonium chloride or zinc chloride composite aqueous solution.

5. The hot-dip galvanizing method for angle steel according to claim 1, characterized in that: In step 3, during the process of lowering the angle steel into the galvanizing bath by a gantry crane, the gantry crane first puts one end of the angle steel into the galvanizing bath and contacts the zinc plating solution and keeps it stationary. Then, the gantry crane continuously reduces the angle of the other end of the angle steel before lowering it into the galvanizing bath until both ends of the angle steel are at the same horizontal level in the galvanizing bath.

6. The hot-dip galvanizing method for angle steel according to claim 1, characterized in that: In step 3, during the lifting process of the angle steel by the gantry crane, the gantry crane lifts one end of the angle steel first, and then lifts the other end of the angle steel, so that the two ends of the angle steel are at an angle of not less than 60°, and waits for the excess zinc plating liquid on the surface of the angle steel to drip off with the tilt angle of the angle steel.

7. The hot-dip galvanizing method for angle steel according to claim 1, characterized in that: In step 3, the water in the cooling pool, once it reaches 35°C, can be introduced into step 3 as warm water for rinsing iron salts. If the temperature exceeds 60°C, cold water is added to assist in controlling the temperature between 35°C and 60°C.