Angle steel hot galvanizing method

Abstract

The angle steel hot galvanizing method comprises the steps that firstly, high-pressure washing rust removal is conducted, wherein angle steel is transferred to a washing area through a crane; rust blocks on the surface of the angle steel are washed off under high pressure, then the angle steel is subjected to acid pickling through the composite rust removal solvent, dithiocar-bamate in the composite rust removal solvent can remove oil stains on the angle steel, and the composite rust removal solvent has a corrosion inhibition effect and can replace corrosion inhibition for use; the lauryl sodium sulfate can wet and permeate the angle steel and has the effect of inhibiting acid mist on the angle steel, the method is good in derusting effect, free of rusty spots, high in pickling speed and free of sludge generation caused by over-pickling, then warm water is adopted for flushing, most of ferric salt and oxide can be removed, a salt film deposited after angle steel pickling is complete and uniform, and the corrosion resistance of the angle steel is improved. And the problems of skip plating, virtual plating and insufficient zinc plating adhesive force do not exist after zinc plating, and the quality and efficiency of angle steel zinc plating are improved.

Description

Technical Field

[0001] The invention relates to the technical field of hot-dip galvanizing, in particular to a method for hot-dip galvanizing angle steel. Background Art

[0002] The optimization process of hot-dip galvanizing refers to making the process more reasonable and scientific. Its purpose is to improve the surface quality of angle steel, reduce the amount of iron and other impurities that affect zinc consumption, control the occurrence of unqualified products, and reduce the cost of galvanizing. In order to ensure the adhesion of angle steel hot-dip galvanizing, pickling is essential for the pre-processing of angle steel hot-dip galvanizing. At present, angle steel is pickled by a single hydrochloric acid or sulfuric acid aqueous 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 aqueous solution cannot make the surface of the angle steel completely clean, and rust spots will remain unremoved. When the angle steel enters the molten zinc liquid, the rust spots hinder the steel matrix surface from reacting with zinc to form a zinc-iron alloy layer, thereby generating missed plating points (blocks), resulting in rework and heavy plating; if a single hydrochloric acid or sulfuric acid aqueous solution is used for excessive pickling, it will produce highly adhesive mud residue that is difficult to remove on the steel surface.

[0003] Therefore, a method for hot-dip galvanizing of angle steel is proposed to solve this problem. Summary of the invention

[0004] The purpose of the present invention is to provide a method for hot-dip galvanizing angle steel, which solves the problem that the angle steel is currently pickled with a single hydrochloric acid or sulfuric acid aqueous solution, the pickling is not clean, the pickling time is too long, the angle steel will produce highly adhesive mud residue, and it is difficult to remove.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for hot-dip galvanizing of angle steel, comprising the following steps: Step 1: High-pressure water washing and rust removal: The angle steel is transferred to the water washing area by a crane, and high-pressure water is sprayed on the angle steel by a high-pressure water gun to wash away impurities and some rust blocks on the surface of the angle steel; Step 2: Rust removal with composite rust remover: transfer the angle steel to the pickling tank by means of a crane and sink it into the pickling tank for pickling. The pickling time is 1h-5h; Add a composite rust removal solvent into the pickling tank, the composite rust removal agent includes 10-30 parts of a surfactant, 10-20 parts of a wetting agent, 10-40 parts of a 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 by composite plating agent: lift the angle steel by crane and transfer it to the water washing area for high pressure washing again to dissolve the iron salt adhering to the angle steel and reduce the iron salt brought into the next process. Use warm water for washing; After rinsing and drying, the steel is transferred to the plating tank by a crane. The steel angle is sunk into the plating tank, where the plating agent removes iron from the steel angle and cleans the iron salts or oxides remaining on the surface of the steel angle, so that the steel parts have the maximum surface activity when entering the zinc bath, and a layer of salt film is deposited on the surface of the steel angle, and then dried to enter the next step; Step 4: Hot-dip galvanizing: The angle steel is transferred to the galvanizing pool by means of a crane, and the angle steel is sunk into the galvanizing pool for galvanizing; Step 5: Water cooling: The angle steel with excess galvanizing liquid dripping off is transferred to the cooling pool by a crane, and the angle steel is sunk into the water of the cooling pool for cooling; Step 6: Passivation: The cooled angle steel is transferred to the passivation tank by a crane and sunk into the passivation tank for passivation; Step 7: Inspection and packaging: The angle steel is transferred to the inspection site by a crane to check whether the angle steel is qualified, and then packaged and stored.

[0006] Preferably, in step 1, during the pickling process, rust on the surface of the angle steel is corroded and separated from the surface of the angle steel, and oil stains on the surface of the angle steel are corroded and separated from the angle steel.

[0007] Preferably, in step 2, the temperature of the warm water is at least greater than 35°C.

[0008] Preferably, in step 2, the plating assistant is mainly one of ammonium chloride or zinc chloride composite aqueous solutions.

[0009] Preferably, in step 3, when the angle steel is sunk into the galvanizing pool by the crane, the crane first puts one end of the angle steel into the galvanizing pool to contact the galvanizing liquid and keeps it still, and then the crane puts the other end of the angle steel into the galvanizing pool while continuously reducing the angle until both ends of the angle steel are on the same horizontal line in the galvanizing pool.

[0010] Preferably, in step 3, when the angle steel is lifted by a crane, the crane lifts one end of the angle steel first and then the other end of the angle steel, and makes the two ends of the angle steel at an angle of not less than 60°, waiting for excess galvanizing liquid on the surface of the angle steel to drip along with the tilt angle of the angle steel.

[0011] Preferably, in step 3, the water in the cooling pool can be introduced into step 3 as warm water for flushing iron salts after reaching 35°C. If it exceeds 60°C, cold water is added to assist in controlling the temperature between 35-60°C.

[0012] Compared with the prior art, the present invention has the following beneficial effects: The invention uses high pressure to flush away rust blocks on the surface of the angle steel, and then pickles the angle steel with a composite rust removal solvent. The dithiocarbamate in the composite rust removal solvent can remove oil stains on the angle steel, has a corrosion inhibition effect and can be used instead of corrosion inhibition. TX-10 can be used to activate and penetrate the angle steel, and sodium dodecyl sulfate can be used to wet and penetrate the angle steel, and it also has the effect of inhibiting acid mist on the angle steel. The method has a good rust removal effect, does not leave rust spots, and has a fast pickling speed, and does not cause mud residue to be generated by over-pickling. After rinsing with warm water, most of the iron salts and oxides can be removed. The salt film deposited on the angle steel after pickling is complete and uniform, and there is no leakage point or discontinuity of the salt film. After galvanizing, there is no problem of missing plating, false plating, and insufficient galvanizing adhesion, thereby improving the quality and efficiency of galvanizing of the angle steel. DETAILED DESCRIPTION

[0013] The present invention will be described in more detail below by way of examples, which are merely illustrative and do not in any way limit the scope of the present invention.

[0014] The present invention provides a technical solution: a method for hot-dip galvanizing of angle steel, comprising the following steps: Step 1: High-pressure water washing and rust removal: The angle steel is transferred to the water washing area by a crane, and high-pressure water is sprayed on the angle steel by a high-pressure water gun to wash away impurities and some rust blocks on the surface of the angle steel; Step 2: Rust removal with composite rust remover: transfer the angle steel to the pickling tank by means of a crane and sink it into the pickling tank for pickling. The pickling time is 1h-5h; Add a composite rust removal solvent into the pickling tank, the composite rust removal agent includes 10-30 parts of a surfactant, 10-20 parts of a wetting agent, 10-40 parts of a 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 by composite plating agent: lift the angle steel by crane and transfer it to the water washing area for high pressure washing again to dissolve the iron salt adhering to the angle steel and reduce the iron salt brought into the next process. Use warm water for washing; After rinsing and drying, the steel is transferred to the plating tank by a crane. The steel angle is sunk into the plating tank, where the plating agent removes iron from the steel angle and cleans the iron salts or oxides remaining on the surface of the steel angle, so that the steel parts have the maximum surface activity when entering the zinc bath, and a layer of salt film is deposited on the surface of the steel angle, and then dried to enter the next step; Step 4: Hot-dip galvanizing: The angle steel is transferred to the galvanizing pool by means of a crane, and the angle steel is sunk into the galvanizing pool for galvanizing; Step 5: Water cooling: Use a crane to transfer the angle steel with excess galvanizing liquid dripping off to the cooling pool, and sink the angle steel into the water of the cooling pool for cooling; Step 6: Passivation: The cooled angle steel is transferred to the passivation tank by a crane and sunk into the passivation tank for passivation; Step 7: Inspection and packaging: The angle steel is transferred to the inspection site by a crane to check whether the angle steel is qualified, and then packaged and stored.

[0015] Embodiment 1: Rust removal by high-pressure water washing: transfer the angle steel to the water washing area by means of a crane, spray high-pressure water on the angle steel by means of a high-pressure water gun, flush and peel off impurities and some rust blocks on the surface of the angle steel; Rust removal by composite rust remover: transfer the angle steel to the pickling tank by means of a crane, and sink it into the pickling tank for pickling, the pickling time being 1h-5h; add a composite rust removal solvent into the pickling tank, the composite rust remover comprises 10-30 parts of a surfactant, 10-20 parts of a wetting agent, 10-40 parts of a composite solvent and 30-60 parts of water; the composite solvent is a dithiocarbamate, the surfactant is TX-10, and the wetting agent is sodium dodecyl sulfate; Iron removal by composite plating agent: lift the angle steel by means of a crane and transfer it to the water washing area for high-pressure flushing again, flushing the dissolved iron salts adhering to the angle steel to reduce the iron salts brought into the next process. The iron salt in the steel is removed, and warm water is used for rinsing; after rinsing and drying, the steel is transferred to the plating-assisting tank by a crane, and the angle steel is sunk into the plating-assisting tank. The plating-assisting agent in the plating-assisting tank removes the iron from the angle steel and cleans the iron salt or oxide remaining on the surface of the angle steel, so that the steel parts have the greatest surface activity when entering the zinc bath, and a layer of salt film is deposited on the surface of the angle steel, and then it is dried to enter the next step; hot-dip galvanizing: the angle steel is transferred to the galvanizing tank by a crane, and the angle steel is sunk into the galvanizing tank for galvanizing; water cooling: the angle steel with excess galvanizing liquid dripping off is transferred to the cooling tank by a crane, and the angle steel is sunk into the water in the cooling tank for cooling; passivation: the cooled angle steel is transferred to the passivation tank by a crane, and is sunk into the passivation tank for passivation; inspection and packaging: the angle steel is transferred to the inspection site by a crane, and the angle steel is inspected to be qualified, and then it is packaged and put into storage.

[0016] Embodiment 2: In embodiment 1, the following steps are added: In step 1, during the pickling process, the rust on the angle steel surface is corroded and separated from the angle steel surface, and the oil stain on the angle steel surface is corroded and separated from the angle steel.

[0017] High-pressure water washing and rust removal: transfer the angle steel to the water washing area through a crane, spray high-pressure water on the angle steel through a high-pressure water gun, flush and peel off the impurities and some rust blocks on the surface of the angle steel. During the pickling process, the rust on the surface of the angle steel is corroded and separated from the angle steel surface, and the oil on the surface of the angle steel is corroded and separated from the angle steel; Rust removal with composite rust remover: transfer the angle steel to the pickling tank through a crane, and sink it into the pickling tank for pickling, and the pickling time is 1h-5h; add a composite rust removal solvent in the pickling tank, and 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; Composite plating agent iron removal: lift the angle steel by a crane and transfer it to the water washing area for high-pressure washing again, flushing the impurities on the angle steel Dissolve the adhered iron salts and reduce the iron salts carried into the next process. Use warm water for rinsing. After rinsing and drying, transfer the steel angles to the plating-assisting tank by a crane. The angles are sunk into the plating-assisting tank. The plating-assisting agent in the plating-assisting tank removes iron from the angles and cleans the iron salts or oxides remaining on the surface of the angles, so that the steel parts have the greatest surface activity when entering the zinc bath, and a layer of salt film is deposited on the surface of the angles. After that, they are dried and enter the next step. Hot-dip galvanizing: The angles are transferred to the galvanizing tank by a crane and sunk into the galvanizing tank for galvanizing. Water cooling: The angles with excess galvanizing liquid dripping off are transferred to the cooling tank by a crane and sunk into the water in the cooling tank for cooling. Passivation: The cooled angles are transferred to the passivation tank by a crane and sunk into the passivation tank for passivation. Inspection and packaging: The angles are transferred to the inspection site by a crane to inspect whether they are qualified, and then packaged and put into storage.

[0018] Embodiment 3: In embodiment 2, the following steps are added: In step 2, the temperature of the warm water is at least greater than 35° C., and the plating assistant is mainly one of ammonium chloride or zinc chloride composite aqueous solutions.

[0019] High-pressure water washing and rust removal: transfer the angle steel to the water washing area through a crane, spray high-pressure water on the angle steel through a high-pressure water gun, flush and peel off the impurities and some rust blocks on the surface of the angle steel. 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; Rust removal with composite rust remover: transfer the angle steel to the pickling tank through a crane, and sink it into the pickling tank for pickling, and the pickling time is 1h-5h; add a composite rust removal solvent in the pickling tank, the composite rust remover includes 10-30 parts of a surfactant, 10-20 parts of a wetting agent, 10-40 parts of a composite solvent and 30-60 parts of water; the composite solvent is a dithiocarbamate, the surfactant is TX-10, the wetting agent is sodium dodecyl sulfate, the warm water temperature is at least greater than 35°C, and the plating aid is mainly one of ammonium chloride or zinc chloride composite aqueous solutions; Composite plating aid iron removal: lift the angle steel by a crane and transfer it to the water The washing area is rinsed with high pressure again to dissolve the iron salts adhering to the angle steel and reduce the iron salts carried into the next process. Warm water is used for rinsing. After rinsing and drying, the angle steel is transferred to the plating-assisting tank by a crane. The angle steel is sunk into the plating-assisting tank. The plating-assisting agent in the plating-assisting 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 the maximum surface activity when entering the zinc bath, and a layer of salt film is deposited on the surface of the angle steel, and then dried to enter the next step. Hot-dip galvanizing: The angle steel is transferred to the galvanizing tank by a crane and sunk into the galvanizing tank for galvanizing. Water cooling: The angle steel with excess galvanizing liquid dripping off is transferred to the cooling tank by a crane and sunk into the water of the cooling tank for cooling. Passivation: The cooled angle steel is transferred to the passivation tank by a crane and sunk into the passivation tank for passivation. Inspection and packaging: The angle steel is transferred to the inspection site by a crane to inspect whether the angle steel is qualified, and then packaged and put into storage.

[0020] Embodiment 4: In embodiment 3, the following steps are added: In step 3, when the angle steel is sunk into the galvanizing pool by the crane, the crane first puts one end of the angle steel into the galvanizing pool and contacts the galvanizing liquid and keeps it still, and then the crane puts the other end of the angle steel into the galvanizing pool while continuously reducing the angle until both ends of the angle steel are at the same horizontal line in the galvanizing pool. When the angle steel is lifted by the crane, the crane first lifts one end of the angle steel and then lifts the other end of the angle steel, and makes both ends of the angle steel at an angle of not less than 60°, waiting for the excess galvanizing liquid on the surface of the angle steel to drip along with the tilt angle of the angle steel. After the water in the cooling pool reaches 35°C, it can be introduced into step 3 as warm water for flushing iron salts. If it exceeds 60°C, cold water is added to assist and its temperature is controlled between 35-60°C.

[0021] High-pressure water washing and rust removal: The angle steel is transferred to the water washing area by a crane, and high-pressure water is sprayed on the angle steel by a high-pressure water gun to wash and peel off the impurities and some rust blocks on the surface of the angle steel. During the pickling process, the rust on the surface of the angle steel is corroded and separated from the angle steel surface, and the oil stains on the surface of the angle steel are corroded and separated from the angle steel; Rust removal with composite rust remover: The angle steel is transferred to the pickling tank by a crane and sunk into the pickling tank for pickling, and the pickling time is 1h-5h; a composite rust removal solvent is added to the pickling tank, and the composite rust remover includes 10-30 parts of a surfactant, 10-20 parts of a wetting agent, 10-40 parts of a composite solvent and 30-60 parts of water; The composite solvent is dithiocarbamate, the surfactant is TX-10, the wetting agent is sodium dodecyl sulfate, the warm water temperature is at least greater than 35°C, and the plating agent is mainly one of the composite aqueous solutions of ammonium chloride or zinc chloride; Composite plating agent iron removal: The angle steel is lifted by a crane and transferred to the water washing area for high-pressure washing again to dissolve the iron salts adhering to the angle steel and reduce the iron salts brought into the next process. The washing water is warm water. During the process of the angle steel being sunk into the galvanizing tank by the crane, the crane first puts one end of the angle steel into the galvanizing tank to contact with the galvanizing liquid and keeps it still, and then the crane continuously reduces the angle of the other end of the angle steel and puts it into the galvanizing tank. Until both ends of the angle steel are at the same horizontal line in the galvanizing pool, the angle steel is lifted by the crane. The crane lifts one end of the angle steel first and then the other end of the angle steel, and makes both ends of the angle steel at an angle of not less than 60°, waiting for the excess galvanizing liquid on the surface of the angle steel to drip along the tilt angle of the angle steel. After the water in the cooling pool reaches 35°C, it can be introduced into step 3 as warm water for flushing iron salts. If it exceeds 60°C, cold water is added to assist and its temperature is controlled between 35-60°C. After rinsing and drying, it is transferred to the auxiliary plating pool by the crane. By sinking the angle steel into the auxiliary plating pool, the auxiliary plating agent in the auxiliary plating pool removes iron from the angle steel and cleans it. The iron salts or oxides remaining on the surface of the angle steel make the steel parts have the greatest surface activity when entering the zinc bath, and a layer of salt film is deposited on the surface of the angle steel, which is then dried and enters the next step; hot-dip galvanizing: the angle steel is transferred to the galvanizing pool by a crane, and the angle steel is sunk into the galvanizing pool for galvanizing; water cooling: the angle steel with excess galvanizing liquid dripping off is transferred to the cooling pool by a crane, and the angle steel is sunk into the water in the cooling pool for cooling; passivation: the cooled angle steel is transferred to the passivation pool by a crane, and sunk into the passivation pool for passivation; inspection and packaging: the angle steel is transferred to the inspection site by a crane, and the angle steel is inspected for qualification, and then packaged and put into storage.

[0022] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for hot-dip galvanizing of angle steel, characterized in that: The following steps are involved: Step 1: High-pressure water washing and rust removal: The angle steel is transferred to the water washing area by a crane, and high-pressure water is sprayed on the angle steel by a high-pressure water gun to wash away impurities and some rust blocks on the surface of the angle steel; Step 2: Rust removal with composite rust remover: transfer the angle steel to the pickling tank by means of a crane and sink it into the pickling tank for pickling. The pickling time is 1h-5h; Add a composite rust removal solvent into the pickling tank, the composite rust removal agent includes 10-30 parts of a surfactant, 10-20 parts of a wetting agent, 10-40 parts of a 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 by composite plating agent: lift the angle steel by crane and transfer it to the water washing area for high pressure washing again to dissolve the iron salt adhering to the angle steel and reduce the iron salt brought into the next process. Use warm water for washing; After rinsing and drying, the steel is transferred to the plating tank by a crane. The steel angle is sunk into the plating tank, where the plating agent removes iron from the steel angle and cleans the iron salts or oxides remaining on the surface of the steel angle, so that the steel parts have the maximum surface activity when entering the zinc bath, and a layer of salt film is deposited on the surface of the steel angle, and then dried to enter the next step; Step 4: Hot-dip galvanizing: The angle steel is transferred to the galvanizing pool by means of a crane, and the angle steel is sunk into the galvanizing pool for galvanizing; Step 5: Water cooling: Use a crane to transfer the angle steel with excess galvanizing liquid dripping off to the cooling pool, and sink the angle steel into the water of the cooling pool for cooling; Step 6: Passivation: The cooled angle steel is transferred to the passivation tank by a crane and sunk into the passivation tank for passivation; Step 7: Inspection and packaging: The angle steel is transferred to the inspection site by a crane to check whether the angle steel is qualified, and then packaged and stored.

2. A method for hot-dip galvanizing of 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 stain on the surface of the angle steel is corroded and separated from the angle steel.

3. A method for hot-dip galvanizing of 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. A method for hot-dip galvanizing of angle steel according to claim 1, characterized in that: In step 2, the plating assistant is mainly one of ammonium chloride or zinc chloride composite aqueous solutions.

5. A method for hot-dip galvanizing of angle steel according to claim 1, characterized in that: In step 3, when the angle steel is sunk into the galvanizing pool by the crane, the crane first puts one end of the angle steel into the galvanizing pool to contact the galvanizing liquid and keeps it still, and then the crane puts the other end of the angle steel into the galvanizing pool while continuously reducing the angle until both ends of the angle steel are at the same horizontal line in the galvanizing pool.

6. A method for hot-dip galvanizing of angle steel according to claim 1, characterized in that: In step 3, when the angle steel is lifted by the overhead crane, the overhead crane lifts one end of the angle steel first and then the other end of the angle steel, and makes the two ends of the angle steel at an angle of not less than 60°, waiting for the excess galvanizing liquid on the surface of the angle steel to drip along with the tilt angle of the angle steel.

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