Hot galvanizing treatment process for improving circulation of zinc liquid

Abstract

The invention relates to the technical field of hot galvanizing treatment processes, in particular to a hot galvanizing treatment process for improving liquid zinc circulation. The method comprises the following steps: pickling: removing surface oxides of a steel workpiece by adopting a pickling solution; plating assisting: immersing the workpiece subjected to acid pickling into a plating assisting solution to generate a zinc amine chloride composite salt film; hot-dip galvanizing is conducted, specifically, the workpiece subjected to plating assisting is immersed in molten composite galvanizing liquid to obtain a metal covering layer; water cooling is conducted after hot-dip galvanizing, and the workpiece in the high-temperature state after hot-dip galvanizing is completed is rapidly cooled; and passivation of a zinc coating: immersing the galvanized workpiece in a passivation solution for passivation to generate a passivation film. The cyclic utilization rate of the hot-dip galvanizing liquid is increased, the energy consumption of equipment is reduced, and the waste liquid discharge amount of enterprises is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of hot-dip galvanizing treatment technology, in particular to a hot-dip galvanizing treatment technology for improving the circulation of zinc liquid. Background Art

[0002] Hot-dip galvanizing is a method of obtaining a metal coating on steel parts. The surface of the plated part is first cleaned and pretreated, and then immersed in molten zinc liquid. Through the reaction and diffusion between iron and zinc, a layer of zinc is plated on the surface of the plated part to improve the corrosion resistance of the steel material.

[0003] In the prior art, since the steel parts are large and numerous, a large amount of galvanizing liquid is used to immerse the steel parts during the hot-dip galvanizing process. The galvanizing liquid that has not been improved is difficult to recycle. After the hot-dip galvanizing is completed, it is discharged with the waste liquid, which not only increases the discharge burden of the waste liquid, increases the energy consumption of the equipment, but also increases the waste liquid treatment cost of the enterprise, which is contrary to the enterprise's development concept of energy conservation and environmental protection. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a hot-dip galvanizing treatment process for improving the circulation of zinc liquid, aiming to improve the recycling rate of hot-dip galvanizing liquid, reduce energy consumption, reduce the amount of waste liquid discharged by the enterprise, and save costs.

[0005] In order to achieve the above object, the present invention provides a hot-dip galvanizing process for improving the circulation of zinc liquid, which specifically comprises the following steps: Pickling, using pickling liquid to remove surface oxides from steel workpieces; Plating assistance: immersing the pickled workpiece into a plating assistance solution to form a zinc chloride amine composite salt film; Hot-dip galvanizing: immersing the galvanized workpiece into a molten composite galvanizing solution to obtain a metal coating; Water cooling after hot dip galvanizing can quickly cool the workpiece at high temperature after hot dip galvanizing. Passivation of the galvanized layer: immerse the galvanized workpiece in the passivation solution to passivate and form a passivation film.

[0006] Furthermore, the pickling solution is a 5 wt% to 15 wt% hydrochloric acid solution, the pickling time is 5 min to 10 min, and the iron salt concentration is less than 15 wt%.

[0007] Furthermore, the plating-aiding solution is a mixed solution of zinc chloride and ammonium chloride, the plating-aiding time is 2 min to 5 min, the plating-aiding workpiece drying temperature is 200 ° C, and the drying time is 2 min to 5 min.

[0008] Furthermore, the temperature of the composite galvanizing solution for immersing the steel workpiece is 400°C to 450°C, and the hot-dip galvanizing time depends on the thickness of the workpiece. The thicker the workpiece, the longer the immersion time.

[0009] Furthermore, the composite zinc plating solution includes 10 parts of zinc chloride, 2 to 3 parts of ammonium chloride, 1 to 1.5 parts of potassium chloride, 1 to 1.5 parts of sodium hydroxide, 2.5 to 3.5 parts of triethanolammonium, 0.5 to 1 part of brightener, 5 to 7 parts of deionized water, and 0.5 to 1 part of zinc powder.

[0010] Furthermore, the brightener ingredients include benzyl acetone, nonylphenol polyoxyethylene ether, sodium benzoate, nicotinic acid, ZY-1 high temperature carrier, diffusing agent NNO and the like.

[0011] Furthermore, the composite zinc plating solution needs to be adjusted to a pH value within the range of 5 to 6 using a hydrochloric acid solution.

[0012] Furthermore, the composite zinc plating solution needs to be stirred and heated at 45°C to 55°C for 1.5 h to 2 h.

[0013] Furthermore, the composite galvanizing liquid that has been used to immerse the steel workpiece is recycled and reused through circulation purification.

[0014] Furthermore, the water cooling temperature is 30°C to 50°C, and the water cooling time depends on the size and thickness of the workpiece.

[0015] Furthermore, the temperature of the passivation solution of the steel workpiece is maintained at 40 ℃~50 ℃, the pH value of the passivation solution is 1.5~2, and the processing time is 10 s~20 s.

[0016] Beneficial Effects The present invention improves the composition and ratio of the composite zinc plating solution so that the components act synergistically, and the composite zinc plating solution has better wear resistance and corrosion resistance after plating; at the same time, the composite zinc plating solution can be recovered and reused through circulating purification treatment, which not only improves the recycling rate of the zinc solution, but also reduces the energy consumption of the equipment and saves the enterprise's waste liquid treatment cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Process flow chart of hot-dip galvanizing process to improve zinc liquid circulation. DETAILED DESCRIPTION

[0018] Embodiments of the present invention are described in detail below. The embodiments described below are illustrative and intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0019] The present invention provides a technical solution A hot-dip galvanizing process for improving the circulation of zinc liquid, specifically comprising the following steps: Pickling, using pickling liquid to remove surface oxides from steel workpieces; Plating assistance: immersing the pickled workpiece into a plating assistance solution to form a zinc chloride amine composite salt film; Hot-dip galvanizing: the workpiece after galvanizing is placed in a molten composite galvanizing solution to obtain a metal coating; Water cooling after hot dip galvanizing can quickly cool the workpiece at high temperature after hot dip galvanizing. Passivation of the galvanized layer: immerse the galvanized workpiece in the passivation solution to passivate and form a passivation film.

[0020] In this embodiment, preferably, the pickling solution is a 10 wt% hydrochloric acid solution, the pickling time is 8 min, and the iron salt concentration is less than 15 wt%. Appropriate hydrochloric acid solution concentration, time and iron salt concentration ensure the pickling quality and speed of the steel workpiece.

[0021] In this embodiment, preferably, the plating solution is a mixed solution of zinc chloride and ammonium chloride, the plating time is 4 minutes, the plating workpiece drying temperature is 200 ° C, and the drying time is 4 minutes. After the plating workpiece is assisted by the plating solution, a layer of zinc chloride amine composite salt film will be covered on the surface. When the temperature reaches 200 ° C, the ammonium chloride in the salt film decomposes into NH3 and HCl. HCl reacts with the iron oxide on the surface of the workpiece and the zinc oxide on the surface of the zinc bath, so that the interface between the workpiece and the zinc bath can be purified.

[0022] In this embodiment, preferably, the temperature of the composite galvanizing solution for immersing the steel workpiece is 400°C to 450°C, and the hot-dip galvanizing time depends on the thickness of the workpiece. The thicker the workpiece, the longer the immersion time.

[0023] In this embodiment, preferably, the composite zinc plating solution includes 10 parts of zinc chloride, 2.5 parts of ammonium chloride, 1.2 parts of potassium chloride, 1 part of sodium hydroxide, 3 parts of triethanolammonium, 0.8 parts of brightener, 6 parts of deionized water, and 0.8 parts of zinc powder. Specifically, the brightener ingredients include benzyl acetone, nonylphenol polyoxyethylene ether, sodium benzoate, nicotinic acid, ZY-1 high temperature carrier, diffusant NNO, etc., which are used to enhance the glossiness of steel workpieces.

[0024] In this embodiment, preferably, the composite zinc plating solution needs to be adjusted to a pH within the range of 5 to 6 using a hydrochloric acid solution.

[0025] In this embodiment, preferably, the composite zinc plating solution needs to be stirred and heated at 50°C to 55°C for 1.5 h.

[0026] In this embodiment, preferably, the composite galvanizing liquid that has been immersed in the steel workpiece is recycled and reused through circulation purification. The raw materials in the composite galvanizing liquid are environmentally friendly and pollution-free, the preparation of the composite galvanizing liquid is simple and convenient, and the preparation process does not produce wastewater, waste gas and other substances that pollute the environment. The composite galvanizing liquid can be recycled and reused, which not only improves the recycling rate of the zinc liquid, but also reduces the energy consumption of the equipment; through the synergistic effect between the various components of the composite galvanizing liquid, the zinc plating liquid has better wear resistance and corrosion resistance after coating.

[0027] In this embodiment, preferably, the water cooling temperature is 35°C to 40°C, and the water cooling time depends on the size and thickness of the workpiece. If the water cooling temperature is too low, the galvanized layer will crack, and if the water cooling temperature is too high, the galvanized layer on the surface of the workpiece will darken, and the effect of rapid cooling cannot be achieved, which reduces the quality of hot-dip galvanizing.

[0028] In this embodiment, preferably, the temperature of the passivation solution of the steel workpiece is maintained at 45°C-50°C, the pH value of the passivation solution is 1.5-2, and the processing time is 15 s.

Claims

1. A hot dip galvanizing process for improving the circulation of zinc liquid, characterized in that: The following steps are included: Pickling, using pickling liquid to remove surface oxides from steel workpieces; Plating assistance: immersing the pickled workpiece into a plating assistance solution to form a zinc chloride amine composite salt film; Hot-dip galvanizing: the workpiece after galvanizing is placed in a molten composite galvanizing solution to obtain a metal coating; Water cooling after hot dip galvanizing can quickly cool the workpiece at high temperature after hot dip galvanizing. Passivation of the galvanized layer: immerse the galvanized workpiece in the passivation solution to passivate and form a passivation film.

2. The hot-dip galvanizing process for improving zinc liquid circulation according to claim 1, characterized in that: The pickling solution is a 5 wt% to 15 wt% hydrochloric acid solution, the pickling time is 5 min to 10 min, and the iron salt concentration is less than 15 wt%.

3. The hot-dip galvanizing process for improving zinc liquid circulation according to claim 1, characterized in that: The auxiliary plating solution is a mixed solution of zinc chloride and ammonium chloride, the auxiliary plating time is 2 min to 5 min, the auxiliary plating workpiece drying temperature is 200°C, and the drying time is 2 min to 5 min.

4. The hot-dip galvanizing process for improving zinc liquid circulation according to claim 1, characterized in that: The temperature of the composite galvanizing solution for immersing the steel workpiece is 400°C to 450°C, and the hot-dip galvanizing time depends on the thickness of the workpiece. The thicker the workpiece, the longer the immersion time.

5. The hot-dip galvanizing process for improving zinc liquid circulation according to claim 4, characterized in that: The composite zinc plating solution comprises 10 parts of zinc chloride, 2-3 parts of ammonium chloride, 1-1.5 parts of potassium chloride, 1-1.5 parts of sodium hydroxide, 2.5-3.5 parts of triethanolammonium, 0.5-1 part of brightener, 5-7 parts of deionized water, and 0.5-1 part of zinc powder.

6. The hot-dip galvanizing process for improving zinc liquid circulation according to claim 5, characterized in that: The composite zinc plating solution needs to be adjusted to a pH within the range of 5 to 6 using a hydrochloric acid solution.

7. The hot-dip galvanizing process for improving zinc liquid circulation according to claim 5, characterized in that: The composite zinc plating solution needs to be stirred and heated at 45°C to 55°C for 1.5 h to 2 h.

8. The hot-dip galvanizing process for improving zinc liquid circulation according to claim 5, characterized in that: The composite galvanizing liquid that has been immersed in the steel workpiece is recycled and reused through circulation purification.

9. The hot-dip galvanizing process for improving zinc liquid circulation according to claim 1, characterized in that: The water cooling temperature is 30°C~50°C, and the water cooling time depends on the size and thickness of the workpiece.

10. The hot-dip galvanizing process for improving zinc liquid circulation according to claim 1, characterized in that: The temperature of the passivation solution of the steel workpiece is maintained at 40 ℃~50 ℃, the pH value of the passivation solution is 1.5~2, and the processing time is 10 s~20 s.

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