A hot-dip galvanizing dusting agent and method of use thereof

Abstract

The application provides a hot-dip galvanizing ash-saving agent and a use method thereof, and belongs to the technical field of hot-dip galvanizing. The ash-saving agent comprises the following components in parts by weight: dust removal ash 30-50 parts, aerogel powder 5-15 parts, auxiliary molten salt 20-40 parts, molten salt carrier 5-10 parts and dispersing agent 1-5 parts; wherein the dust removal ash is zinc smoke particles collected in the hot-dip galvanizing process. The dust removal ash generated in the hot-dip galvanizing process is reused as a core raw material, and the mixed ash-saving agent can effectively isolate the molten zinc liquid from contacting with air, inhibit the oxidation of the zinc liquid, build a four-fold synergistic ash-reducing system of "heat insulation+adsorption+covering+reduction", and can reduce the zinc ash production by more than 40%, simultaneously reduce the generation of zinc smoke, and reduce the production cost.

Description

Technical Field

[0001] This invention relates to the field of hot-dip galvanizing technology, and in particular to a hot-dip galvanizing ash-saving agent and its application method. Background Technology

[0002] Hot-dip galvanizing is an effective method to improve the atmospheric corrosion resistance of steel, and it is widely used in power, transportation, communications, construction, and home appliances. The hot-dip galvanizing process is typically an open system. Molten zinc (usually at 440℃~460℃, with the addition of certain amounts of Al, Ni, Mg, etc.) reacts with oxygen and carbon dioxide in the air, inevitably generating a large amount of zinc ash (Zn, ZnO, Al2O3, etc.) and zinc dross. In addition, the workpiece undergoes fluxing treatment before galvanizing, forming a composite salt film containing ZnCl2 and NH4Cl on the workpiece surface. During the galvanizing process, this salt film decomposes under high-temperature conditions, producing NH3, NH4Cl particles, ZnCl2 particles, HCl, water vapor, etc., and reacts with aluminum in the zinc alloy bath to produce AlCl3 gas. Macroscopically, this manifests as the emission of white smoke and the formation of zinc ash on the zinc bath surface. The white smoke is collected as dust by dust removal equipment. More than 80% of zinc ash consists of ZnO and Zn particles carried by human-made ash removal. This not only causes a huge waste of zinc resources (usually accounting for 5% to 15% of zinc consumption) and increases production costs, but also requires additional manpower and time for retrieval and cleaning, which seriously affects production efficiency and coating quality.

[0003] In recent years, with the urgent need for energy conservation and emission reduction in the hot-dip galvanizing industry, people have been constantly innovating in the field of zinc recycling. Patent application CN201010297705.6 discloses a zinc ash reducing agent for hot-dip galvanizing. The zinc ash reducing agent has the following composition: 3%~8% aluminum chloride hexahydrate, 12%~20% coal powder, 0~5% NH4Cl, 25%~8% ZnCl, 50%~60% fluorite powder, 10%~15% NaCl, and 3%~5% KCl. The amount of zinc ash reducing agent added is 0.2%~1% of the mass of zinc ash in the furnace. The zinc ash reducing agent of this invention has the functions of reduction, refining, and covering, and the zinc ash recovery rate is relatively high. However, this zinc ash reducing agent is a secondary treatment after the zinc ash is collected, which increases the process and cost. Patent application CN202510663114.2 discloses a zinc ash recovery and processing machine for a hot-dip galvanizing production line. This machine uses an obstacle avoidance collection mechanism above the hot-dip galvanizing bath to collect zinc ash and automatically avoid obstacles during the collection process. A motor drives a dust collection plate to collect the zinc ash. A guide plate increases the collection area and pushes the collected zinc ash towards the corresponding dust collection box when encountering obstacles, improving the recovery efficiency and quality of the zinc ash. Patent application CN200920169630.6 discloses a device for recovering zinc from zinc ash. This device uses a heatable rotating zinc melting cylinder to recover zinc from the zinc ash. Patent application CN200920243573.1 discloses a zinc ash separator that separates zinc ash from zinc particles through crushing, screening, and collection. These inventions and devices mainly rely on mechanical separation methods for secondary processing of zinc ash, which can recover zinc particles from zinc ash to a certain extent, but the zinc recovery rate from zinc ash is low.

[0004] Furthermore, dust collector ash is a common industrial solid waste in the hot-dip galvanizing industry. Its storage and disposal not only occupy land resources but may also cause secondary pollution. How to achieve its high-value resource utilization is an urgent problem to be solved in this field. Therefore, it is necessary to develop a high-efficiency, low-cost, environmentally friendly, and functionally composite dust-saving agent for hot-dip galvanizing to reduce the waste of zinc resources. Summary of the Invention

[0005] The purpose of this invention is to provide a hot-dip galvanizing ash-saving agent and its application method to solve the problems of large amounts of zinc ash and zinc fumes, serious waste of zinc resources, and difficulty in solid waste treatment in the traditional hot-dip galvanizing process.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a hot-dip galvanizing ash-saving agent, comprising the following components in parts by weight: 30-50 parts dust removal ash, 5-15 parts aerogel powder, 20-40 parts auxiliary molten salt, 5-10 parts molten salt carrier, and 1-5 parts dispersant;

[0008] The dust collected is zinc fume particles collected during the hot-dip galvanizing process;

[0009] The auxiliary molten salt is a mixture of at least two auxiliary molten salts.

[0010] Preferably, the aerogel powder comprises one or more of silica aerogel powder, alumina aerogel powder, and carbon aerogel powder.

[0011] Preferably, the auxiliary molten salt comprises at least two of aluminum chloride hexahydrate, KCl, NaCl, and NaSO4.

[0012] Preferably, the molten salt carrier comprises pulverized coal and / or activated carbon powder.

[0013] Preferably, the particle size of the molten salt carrier is 150-200 mesh.

[0014] Preferably, the dispersant comprises one or more of sodium silicate, sodium carbonate, polyethylene glycol, and zinc stearate.

[0015] The present invention also provides a method for using the above-mentioned hot-dip galvanizing ash-saving agent, wherein the ash-saving agent is sprinkled on the surface of the zinc liquid, and then the workpiece is galvanized.

[0016] Preferably, the initial amount of the ash-saving agent used is 0.1 to 0.3% of the mass of the zinc liquid.

[0017] Preferably, the amount of ash-saving agent supplemented is 0.2 to 0.3% of the workpiece production quality.

[0018] Preferably, the method is applicable to the batch hot-dip galvanizing of steel structural components or the continuous hot-dip galvanizing of steel pipes, profiles, and bars.

[0019] The beneficial effects of this invention are:

[0020] This invention reuses the dust generated during hot-dip galvanizing as a core raw material. The resulting dust-saving agent, through the synergistic effect of its components, effectively isolates the molten zinc from contact with air, inhibits zinc oxidation, and constructs a four-fold synergistic dust reduction system of "heat insulation + adsorption + covering + reduction". This system can reduce zinc dust generation by more than 40%, while also reducing zinc fume generation and lowering production costs.

[0021] This invention reuses dust, a solid waste, as an effective component, which not only reduces the pressure of solid waste disposal but also recovers zinc resources through reduction reactions, achieving the goal of "treating waste with waste and turning waste into treasure," and meeting the needs of green and environmentally friendly production.

[0022] The use of ash-saving agent in this invention has no negative impact on the surface quality of the coating, resulting in a smooth and glossy coating.

[0023] The ash-saving agent of the present invention can be directly spread and used without modifying existing production lines or adding extra processing steps. It is simple to operate, low in cost, and easy to promote and apply on a large scale. Detailed Implementation

[0024] This invention provides a hot-dip galvanizing ash-saving agent, comprising the following components in parts by weight: 30-50 parts dust removal ash, 5-15 parts aerogel powder, 20-40 parts auxiliary molten salt, 5-10 parts molten salt carrier, and 1-5 parts dispersant;

[0025] The dust collected is zinc fume particles collected during the hot-dip galvanizing process;

[0026] The auxiliary molten salt is a mixture of at least two auxiliary molten salts.

[0027] In this invention, the dust removal ash is preferably 35-45 parts by weight, more preferably 38-40 parts by weight; the aerogel powder is preferably 8-12 parts by weight, more preferably 10 parts by weight; the auxiliary molten salt is preferably 25-35 parts by weight, more preferably 30 parts by weight; the molten salt carrier is preferably 7-9 parts by weight, more preferably 8 parts by weight; and the dispersant is preferably 2-4 parts by weight, more preferably 3 parts by weight.

[0028] This invention directly reuses the dust generated during hot-dip galvanizing (traditionally considered solid waste), reducing solid waste accumulation by over 80% and lowering solid waste treatment costs. Furthermore, the dust contains 0%–5% metallic Zn particles and 5%–15% ZnO particles. At the high temperature (440℃–460℃) of the molten zinc, ZnO can undergo a slow reduction reaction with the coal powder / activated carbon powder (reducing components) in the molten salt carrier (ZnO + C → Zn + CO↑), achieving auxiliary recovery of zinc and further reducing zinc consumption. Simultaneously, the Zn and ZnO particles in the dust can act as a "film-forming skeleton," combining with the molten auxiliary salt and aerogel powder to enhance the density of the protective layer and prevent cracking.

[0029] In this invention, the aerogel powder comprises one or more of silica aerogel powder, alumina aerogel powder, and carbon aerogel powder.

[0030] In this invention, the specific surface area of ​​the aerogel powder is ≥500m². 2 / g, thermal conductivity ≤0.02 Furthermore, it undergoes heat treatment at 500~600℃ before use to improve thermal stability.

[0031] Aerogels possess extremely low thermal conductivity and excellent dispersibility, forming a dense, uniform, and highly insulating protective layer on the surface of molten zinc. This effectively reduces high-temperature oxidation and evaporation of the zinc, suppressing zinc ash formation at its source. Aerogels also have a large specific surface area and high adsorption capacity, rapidly adsorbing tiny zinc ash particles and ZnCl2 and AlCl3 particles from the zinc fume, preventing their escape and dust formation. Simultaneously, Zn and ZnO particles in the dust can act as agglomeration nuclei, working in conjunction with the aerogel to promote the aggregation of these tiny particles into larger ones. This makes the zinc ash easier to collect and recover, significantly improving zinc recovery rates.

[0032] In this invention, the auxiliary molten salt comprises at least two of aluminum chloride hexahydrate, KCl, NaCl, and NaSO4.

[0033] In this invention, the auxiliary molten salt is a composite system. Through the eutectic effect, the molten salt system can melt into a liquid state at the actual working temperature of hot-dip galvanizing, thereby having the ability to form a uniform, dense, stable, and self-healing liquid physical barrier. This is the basis for achieving efficient coverage and isolation functions, and thus achieving the goal of reducing ash and smoke.

[0034] In this invention, the molten salt carrier comprises pulverized coal and / or activated carbon powder.

[0035] In this invention, the molten salt carrier is a porous particle that serves as a "carrier skeleton," uniformly loading aerogel powder and auxiliary molten salt onto the surface. This prevents the ash-saving agent from clumping and ensures rapid dispersion after spreading to form a continuous protective layer. Simultaneously, the reducing components (coal powder / activated carbon powder) in the molten salt carrier undergo a slow reduction reaction with the closely contacting dust and ZnO on the zinc bath surface (ZnO + C → Zn + CO↑), achieving auxiliary recovery and continuous replenishment of zinc. This process, synergistically with the physical isolation effect of the covering layer, contributes to the reduction of zinc consumption.

[0036] In this invention, the particle size of the molten salt carrier is 150-200 mesh.

[0037] In this invention, the dispersant comprises one or more of sodium silicate, sodium carbonate, polyethylene glycol, and zinc stearate.

[0038] In this invention, the dispersant can reduce the interfacial tension between the components and prevent the agglomeration of dust and aerogel powder.

[0039] In this invention, the hot-dip galvanizing ash-saving agent can be mixed evenly using a mechanical mixing method.

[0040] The present invention also provides a method for using the above-mentioned hot-dip galvanizing ash-saving agent, wherein the ash-saving agent is sprinkled on the surface of the zinc liquid, and then the workpiece is galvanized.

[0041] In this invention, the ash-saving agent is sprayed onto the surface of the zinc liquid, and the temperature of the zinc liquid is maintained at 440~460℃, so that the ash-saving agent forms a dense protective layer on the surface of the zinc liquid.

[0042] In this invention, the initial amount of the ash-saving agent is 0.1 to 0.3% of the mass of the zinc liquid, specifically 0.1%, 0.2%, or 0.3%.

[0043] In this invention, the amount of ash-saving agent supplemented is 0.2 to 0.3% of the workpiece production quality.

[0044] In this invention, the method of use is applicable to the batch hot-dip galvanizing of steel structural components or the continuous hot-dip galvanizing of steel pipes, profiles, and bars.

[0045] This invention directly reduces the generation of zinc ash and zinc fumes at the source, while realizing the resource recycling of dust ash, resulting in a coating with no damage and convenient and economical application.

[0046] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0047] Example 1

[0048] Mix 30 parts of dust and 10 parts of silica aerogel powder (specific surface area 600 m²). 2 / g, thermal conductivity is 0.018 The ash-saving agent is obtained by mechanically mixing 30 parts of auxiliary molten salt (aluminum chloride hexahydrate, KCl, and NaCl mixed in a mass ratio of 2:1:1), 8 parts of coal powder (average particle size of 180 mesh), and 2 parts of dispersant (sodium silicate and polyethylene glycol mixed in a mass ratio of 1:1). The mixture is heat-treated at 500℃ for 2 hours, 30 parts of auxiliary molten salt (aluminum chloride hexahydrate, KCl, and NaCl mixed in a mass ratio of 2:1:1), 8 parts of coal powder (average particle size of 180 mesh), and 2 parts of dispersant (sodium silicate and polyethylene glycol mixed in a mass ratio of 1:1).

[0049] The process employs a continuous hot-dip galvanizing process for steel pipes, with a zinc pot capacity of 400 t. Initially, 800 kg of ash-saving agent is evenly spread on the surface of the molten zinc, producing a total of 120 t of square tubes (approximately 12,000 m² surface area). 2 For every 10 tons produced, 30 kg of ash-saving agent is added. A small amount of zinc fumes are generated during the hot-dip galvanizing process. The coating surface is smooth and bright, without oxidation spots. The zinc ash generation is approximately 123 g / m³. 2 .

[0050] Example 2

[0051] 38 parts of dust collector ash and 15 parts of alumina aerogel powder (specific surface area 700 m²) were mixed. 2 / g, thermal conductivity is 0.015 The ash-saving agent is obtained by mechanically mixing 25 parts of auxiliary molten salt (aluminum chloride hexahydrate and KCl mixed in a mass ratio of 3:2), 10 parts of molten salt carrier (activated carbon and coal powder mixed in a mass ratio of 1:1 with an average particle size of 160 mesh), and 3 parts of dispersant (sodium silicate and polyethylene glycol mixed in a mass ratio of 1:2). The mixture is heat-treated at 550℃ for 1.5 hours, 10 parts of molten salt carrier (activated carbon and coal powder mixed in a mass ratio of 1:1 with an average particle size of 160 mesh), and 3 parts of dispersant (sodium silicate and polyethylene glycol mixed in a mass ratio of 1:2).

[0052] The process employs a continuous hot-dip galvanizing process for steel pipes, with a zinc pot capacity of 400 t. Initially, 600 kg of ash-saving agent is evenly spread on the surface of the molten zinc, producing a total of 130 t of square tubes (approximately 15,000 m² surface area). 2 For every 10 tons produced, 25 kg of ash-saving agent is added. A small amount of zinc fumes are generated during the hot-dip galvanizing process. The coating surface is smooth and bright, without oxidation spots. The zinc ash generation is approximately 118 g / m³. 2 .

[0053] Example 3

[0054] 45 parts of dust and 8 parts of graphene aerogel powder (specific surface area of ​​600 m²) were mixed. 2 / g, thermal conductivity is 0.015 The ash-saving agent is obtained by mechanically mixing 35 parts of auxiliary molten salt (NaCl, NaSO4, and KCl mixed in a mass ratio of 2:1:1), 8 parts of activated carbon (average particle size of 170 mesh), and 5 parts of dispersant (zinc stearate and polyethylene glycol mixed in a mass ratio of 1:2) after heat treatment at 600℃ for 1 hour, 8 parts of activated carbon (average particle size of 170 mesh), and 5 parts of dispersant (zinc stearate and polyethylene glycol mixed in a mass ratio of 1:2).

[0055] The process employs a batch hot-dip galvanizing process with a zinc pot capacity of 100 t. Initially, 100 kg of ash-saving agent is evenly spread on the zinc ash collection area on the surface of the zinc liquid. A total of 20 t of steel components are produced. For every 3 t produced, 9 kg of ash-saving agent is added. A small amount of zinc fume is generated during the hot-dip galvanizing process. The coating surface is smooth and bright, without oxidation spots. The amount of zinc ash generated is approximately 2 kg / t.

[0056] Example 4

[0057] Mix 50 parts of dust and 10 parts of silica aerogel powder (specific surface area 600 m²). 2 / g, thermal conductivity is 0.015 The ash-saving agent is obtained by mechanically mixing 40 parts of auxiliary molten salt (aluminum chloride hexahydrate, KCl, and NaSO4 mixed in a mass ratio of 2:2:1), 7 parts of coal powder (average particle size of 190 mesh), and 4 parts of dispersant (sodium carbonate and sodium silicate mixed in a mass ratio of 1:1). The mixture is heat-treated at 500℃ for 1.5 hours, 7 parts of coal powder (average particle size of 190 mesh), and 4 parts of dispersant (sodium carbonate and sodium silicate mixed in a mass ratio of 1:1).

[0058] The process employs a batch hot-dip galvanizing process with a zinc pot capacity of 100 t. Initially, 150 kg of ash-saving agent is evenly spread on the zinc ash collection area on the surface of the zinc liquid. A total of 30 t of steel components are produced. For every 3 t produced, 9 kg of ash-saving agent is added. A small amount of zinc fume is generated during the hot-dip galvanizing process. The coating surface is smooth and bright, without oxidation spots. The amount of zinc ash generated is approximately 1.8 kg / t.

[0059] Comparative Example 1

[0060] Using a continuous hot-dip galvanizing process for steel pipes, with a zinc pot capacity of 400 t, and without the use of ash-saving agents, a total of 120 t of square tubes (approximately 12,000 m² surface area) were produced. 2 For every 10 tons produced, 30 kg of ash-saving agent (the ash-saving agent in Example 1) is added. A large amount of zinc fumes are generated during the hot-dip galvanizing process. The coating surface is smooth and bright, without oxidation spots, and the zinc ash generation is approximately 216 g / m³. 2 .

[0061] Comparative Example 2

[0062] The process employs a batch hot-dip galvanizing process with a zinc pot capacity of 100 t. No ash-saving agent is used, and a total of 20 t of steel components are produced. A large amount of zinc fumes are generated during the hot-dip galvanizing process. The coating surface is smooth and bright, without oxidation spots, and the amount of zinc ash generated is approximately 5.3 kg / t.

[0063] Comparative Example 3

[0064] Mix 30 parts of dust and 10 parts of silica aerogel powder (specific surface area 600 m²). 2 / g, thermal conductivity is 0.018 The ash-saving agent is obtained by mechanically mixing 30 parts of auxiliary molten salt (NaCl), 8 parts of coal powder (average particle size of 180 mesh), and 2 parts of dispersant (sodium silicate and polyethylene glycol mixed in a mass ratio of 1:1) after heat treatment at 500℃ for 2 hours.

[0065] The process employs a continuous hot-dip galvanizing process using steel pipes. The zinc pot has a capacity of 400 t. Initially, 800 kg of ash-saving agent is evenly spread on the surface of the molten zinc. The ash-saving agent covers the surface of the molten zinc but does not melt and spread.

[0066] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A hot dip galvanizing dusting agent characterized by comprising, The dust collector comprises the following components in parts by weight: dust collector 30-50 parts, aerogel powder 5-15 parts, auxiliary molten salt 20-40 parts, molten salt carrier 5-10 parts, and dispersant 1-5 parts. The dust collector is zinc fume particles collected in a hot-dip galvanizing process. The auxiliary molten salt is a mixture of at least two auxiliary molten salts.

2. The zinc spangle inhibitor according to claim 1, wherein The aerogel powder comprises one or more of silica aerogel powder, alumina aerogel powder, and carbon aerogel powder.

3. The zinc-flashing agent according to claim 1 or 2, characterized in that, The auxiliary molten salt comprises at least two of aluminum chloride hexahydrate, KCl, and NaCl.

4. The zinc spangle inhibitor according to claim 3, wherein The molten salt carrier comprises coal powder and / or activated carbon powder.

5. The zinc-flashing agent according to claim 1 or 2 or 4, wherein The particle size of the molten salt carrier is 150-200 mesh.

6. The zinc spangle inhibitor according to claim 5, wherein The dispersant comprises one or more of sodium silicate, sodium carbonate, polyethylene glycol, and zinc stearate.

7. The use of a hot dip galvanizing dust suppressant according to any one of claims 1 to 6, characterized in that, The dust collector is sprinkled on the surface of the zinc liquid, and then the workpiece is galvanized.

8. The method of using a zinc spatter inhibitor according to claim 7, wherein The initial usage amount of the dust collector is 0.1-0.3% of the mass of the zinc liquid.

9. The method of using a zinc spatter inhibitor according to claim 8, wherein The supplementary usage amount of the dust collector is 0.2-0.3% of the mass of the workpiece production.

10. A method of using a zinc spatter inhibitor according to claim 8 or 9, characterized in that, The usage method is suitable for batch hot-dip galvanizing of steel structural members or continuous hot-dip galvanizing of steel pipes, profiles, and bars.