Acid pickling accelerant suitable for acid regeneration system and preparation method of acid pickling accelerant

Abstract

The invention discloses a pickling accelerant suitable for an acid regeneration system and a preparation method. The pickling accelerant is prepared from the following raw materials in percentage by weight: 6-17% of a penetrating agent, 1-5% of a stripping agent, 5-10% of a dispersing agent, 1-5% of a stabilizing agent, 1-3% of a foam control agent and the balance of water. The lauryl hydroxyethyl imidazoline is used as a penetrant, and the lauryl hydroxy sulfobetaine is used as a stripping agent, so that the permeation effect of acid liquor on metal oxide skin is accelerated, the whiteness of a plate surface is improved, the color difference is reduced, and the generation of silicon sludge is reduced. And after silicon steel is subjected to acid pickling, the obtained regenerated acid is high in purity, the quality of the byproduct iron oxide powder of an acid regeneration system is improved, and the economical efficiency of resource recovery is improved.

Description

Technical Field

[0001] The present invention relates to the cleaning and degreasing of metal materials by chemical methods other than the electrolysis method, and particularly to a pickling accelerator applicable to an acid regeneration system and its preparation. Background Art

[0002] The pickling of hot-rolled silicon steel is one of the main processes in the production of silicon steel. While pickling removes the oxides and contaminants on the surface of hot-rolled silicon steel, it can reduce the magnetic deterioration points and ensure the application efficiency and stability of the finished silicon steel. In addition to common iron oxides, the scale on the surface of silicon steel also contains silicon oxides and ferrosilicon complexes, and has extremely poor solubility in conventional hydrochloric acid, easily generating precipitated silicon mud, which increases the difficulty of waste acid treatment. At the same time, the high silicon content makes the scale form a denser composite structure, hindering the penetration of the acid solution. The prior art relies on high-concentration acid solutions or fluoride-assisted dissolution. Considering the strict quality requirements for the surface of silicon steel, the pickling efficiency is generally low. Although the addition of reducing compounds to the existing pickling solutions improves the pickling efficiency, the amount of silicon mud increases, resulting in a decrease in the silicon content in the regenerated acid. The magnetic properties and particle size distribution of the regenerated iron oxide powder are contaminated by silicon, and the quality deteriorates. Therefore, it is crucial to develop an acid regeneration system that does not contain reducing agents and produces less silicon mud.

[0003] Chinese invention patent CN1195102C discloses a pickling accelerator for steel, which uses a mixed acid combination of hydrochloric acid, sulfuric acid, and hydrofluoric acid, and can accelerate the removal of the scale formed on the steel and improve the pickling quality of the steel surface. However, it will generate more silicon mud and affect the quality of the regenerated acid. Chinese invention patent CN103526215A discloses a pickling accelerator for silicon steel and its preparation method, which uses a corrosion inhibitor imidazoline derivative and a defoaming agent tributyl phosphate, and has the characteristics of convenient use, low pickling temperature, high efficiency, good "corrosion inhibition" effect, low cost, and environmental friendliness. However, the content of silicon dioxide in the pickling solution after pickling is high, and silicon mud precipitates. Summary of the Invention

[0004] In order to improve the pickling efficiency of hot-rolled silicon steel, reducing compounds (multivalent metal compounds, reducing agents) are generally added to the pickling accelerator in the prior art. However, the reducing agent will reduce the Fe 3+ concentration, and the ability of the acid solution to dissolve silicon is weakened. Fe 2+The coprecipitation effect with silicate results in an increase in silicon mud generated during pickling, which increases the difficulty of waste acid treatment. The waste acid is more likely to deposit in parts such as pipelines, filters, valves, and graphite heat exchangers of the acid regeneration system during acid regeneration, leading to a decrease in acid regeneration efficiency and an increase in the maintenance cost of the acid regeneration system. Moreover, the silicon content in the regenerated acid increases, reducing the purity of the regenerated acid and the process stability when it is reused in the pickling tank. At the same time, indicators such as the magnetic properties and particle size distribution of the regenerated by-product iron oxide powder are contaminated by silicon, and the quality significantly decreases. In order to develop a pickling accelerator without a reducing agent, high pickling efficiency, and less silicon mud generation, the first aspect of the present invention provides a pickling accelerator applicable to an acid regeneration system. The preparation raw materials include, by weight percentage: 6-17% of penetrant, 1-5% of stripper, 5-10% of dispersant, 1-5% of stabilizer, 1-3% of foam control agent, and water is supplemented to 100%.

[0005] As an implementation manner, the weight percentage of the penetrant is 13.8%.

[0006] As an implementation manner, the weight percentage of the stripper is 2-4%.

[0007] As an implementation manner, the weight percentage of the stripper is 3.6%.

[0008] As an implementation manner, the weight percentage of the dispersant is 6-9%.

[0009] As an implementation manner, the weight percentage of the dispersant is 8%.

[0010] As an implementation manner, the weight percentage of the stabilizer is 2-4%.

[0011] As an implementation manner, the weight percentage of the stabilizer is 3.5%.

[0012] As an implementation manner, the weight percentage of the foam control agent is 2%.

[0013] As an implementation manner, the penetrant includes at least one of lauryl hydroxyethyl imidazoline, heptadecenyl amine ethyl imidazoline quaternary ammonium salt, or coconut oil acyl amphoteric diacetic acid disodium salt.

[0014] As an implementation manner, the penetrant is lauryl hydroxyethyl imidazoline.

[0015] As an implementation manner, the stripper includes at least one of lauryl hydroxy sulfobetaine, dodecyl dimethyl betaine, or coconut oil amide propyl betaine.

[0016] As an implementation manner, the stripper is lauryl hydroxy sulfobetaine.

[0017] During the experiment, the inventor found that when lauryldihydroxyethylimidazoline is used as a penetrant and lauryl hydroxy sulfobetaine is used as a stripper, good permeability can still be maintained under strong acid conditions, which can effectively accelerate the penetration of the acid solution into the metal oxide scale. The reasons may be as follows: lauryldihydroxyethylimidazoline has a corrosion inhibition effect on silicon steel for removing the oxide scale, slowly penetrates under strong acid conditions to prevent overpickling, and lauryl hydroxy sulfobetaine exhibits cationic characteristics under acidic conditions and has an adsorption effect on the negatively charged metal oxide scale material, improving the whiteness of the plate surface, reducing color difference, reducing the dissolution of silicon ions into the acid solution while increasing the pickling speed, and reducing the generation of silicon mud.

[0018] As an embodiment, the dispersant includes at least one of polyoxyethylene sorbitan monolaurate, sodium polyacrylate, or arabic gum.

[0019] As an embodiment, the dispersant is polyoxyethylene sorbitan monolaurate.

[0020] As an embodiment, the stabilizer includes at least one of polyethylene glycol octyl phenyl ether or polyoxyethylene mono-tert-octyl phenyl ether.

[0021] As an embodiment, the stabilizer is polyethylene glycol octyl phenyl ether.

[0022] During the experiment, the inventor found that when polyoxyethylene sorbitan monolaurate is used as a dispersant and polyethylene glycol octyl phenyl ether is used as a stabilizer, the content of silicon dioxide in the regenerated acid can be reduced, and the generation of silicon mud can be reduced. The reasons may be that polyoxyethylene sorbitan monolaurate adsorbs on the surface of silicate particles to form a steric hindrance effect, promoting the uniform dispersion of silicic acid particles and avoiding rapid precipitation caused by too high local concentration. And polyethylene glycol octyl phenyl ether controls the formation of an electric double layer on the surface of silicate colloid particles, enhancing the colloidal stability and preventing the colloidal adsorption and aggregation, further avoiding the generation of silicon mud precipitation.

[0023] As an embodiment, the weight ratio of the dispersant to the stabilizer is 8:3.5.

[0024] During the experiment, the inventor found that when the weight ratio of the dispersant to the stabilizer is 8:35, the silicon mud generated by the flocculation of silicate in the acid solution can be effectively reduced, preventing the deposition of silicon mud on equipment such as pipelines and filters in the regeneration system. The reasons may be that the dispersant adsorbs on the surface of silicate particles to form a steric hindrance effect, and an electric double layer is formed on the surface of the silicate colloid particles, enhancing the colloidal stability. The weight ratio of the dispersant to the stabilizer is 8:3.5, achieving the balance of physical stability and electrochemical stability, thereby further reducing the flocculation of silicate silicon mud in the acid solution.

[0025] As an implementation manner, the foam control agent includes at least one of propylene glycol block polyether, polyoxyethylene polyoxypropylene block polyether, polydimethylsiloxane or carbon alcohol defoamer.

[0026] As an implementation manner, the foam control agent is propylene glycol block polyether.

[0027] The inventor uses propylene glycol block polyether as the foam control agent, which can prevent excessive foaming of the pickling accelerator during pickling and avoid the generation of foam during waste acid treatment, which affects acid regeneration treatment. At the same time, propylene glycol block polyether has a cleaning and dispersing effect on oil stains, preventing the influence of oil stains on the surface of silicon steel during pickling.

[0028] The second aspect of the present invention provides a preparation method of a pickling accelerator applicable to an acid regeneration system, including the following steps:

[0029] S1: Add water and start stirring, and add a penetrant under stirring conditions;

[0030] S2: Then add a stripper, a dispersant, a stabilizer and a foam control agent in sequence, mix and stir evenly to obtain a pickling accelerator.

[0031] As an implementation manner, the usage method of the pickling accelerator includes the following steps: Add the pickling accelerator to the acid solution, mix evenly, and pickle the silicon steel in the acid solution added with the pickling accelerator.

[0032] As an implementation manner, the acid solution includes but is not limited to hydrochloric acid.

[0033] As an implementation manner, the concentration of the acid solution is 20%-22%.

[0034] As an implementation manner, the addition concentration of the pickling accelerator is 0.2%-0.5%.

[0035] As an implementation manner, the pickling speed of the silicon steel is 80-110 m / min.

[0036] As an implementation manner, the pickling temperature is 80°C-85°C.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) For the pickling accelerator applicable to the acid regeneration system of the present invention, lauryl hydroxyethyl imidazoline is used as the penetrant and lauryl hydroxy sulfobetaine is used as the stripper, which accelerates the penetration of the acid solution into the metal oxide scale, improves the whiteness of the plate surface, reduces the color difference, and reduces the generation of silicon mud.

[0039] (2) The pickling accelerator applicable to the acid regeneration system in the present invention uses polyoxyethylene sorbitan monolaurate as a dispersant and polyethylene glycol octyl phenyl ether as a stabilizer, which can reduce the content of silicon dioxide in the regenerated acid and reduce the generation of silicon mud.

[0040] (3) In the pickling accelerator of the present invention, the dispersant and the stabilizer are in a weight ratio of 8:35, which can effectively reduce the silicon mud generated by the precipitation of silicate in the acid solution, prevent the deposition of silicon mud on equipment such as pipes, filters, valves, and heat exchangers in the regeneration system, and reduce the blockage of nozzles and pipelines.

[0041] (4) The pickling accelerator described in the present invention is applied to the pickling process of silicon steel. Under the condition of no reducing agent, the pickling speed of silicon steel can be increased by 30%-50%, while improving the pickling efficiency of silicon steel, the difficulty of waste acid treatment is reduced.

[0042] (5) The pickling accelerator applicable to the acid regeneration system in the present invention has a relatively high purity of the regenerated acid after pickling silicon steel, improving the quality of the by-product iron oxide powder in the acid regeneration system and the economy of resource recovery. Detailed implementation mode

[0043] Examples and comparative examples

[0044] A pickling accelerator applicable to the acid regeneration system is prepared with raw materials as shown in Table 1-2 by weight percentage, and the parameters of the usage method of the pickling accelerator are shown in Table 1-2.

[0045] Table 1

[0046]

[0047]

[0048] Table 2

[0049]

[0050]

[0051] The 17-alkenylaminoethyl imidazoline quaternary ammonium salt is purchased from Hubei Kemadi Chemical Co., Ltd., with the brand name ODD.

[0052] The polyoxyethylene sorbitan monolaurate is Tween 20, CAS No.: 9005-64-5.

[0053] The sodium polyacrylate is purchased from Dow Chemical, with the brand name ACUSOL 445N Polymer.

[0054] The polyethylene glycol octyl phenyl ether is purchased from Hai'an Petrochemical Industry, with the brand name: Triton X-100.

[0055] The polyoxyethylene mono-tert-octylphenyl ether is purchased from Hai'an Petrochemical Industry, with the product number: Triton X-114.

[0056] The propylene glycol block polyether is purchased from Hai'an Petrochemical Industry, with the product number: L-64.

[0057] A preparation method of a pickling accelerator applicable to an acid regeneration system comprises the following steps:

[0058] S1: Add water and start stirring, and add a penetrant under stirring conditions;

[0059] S2: Then sequentially add a stripper, a dispersant, a stabilizer and an antifoaming agent, mix and stir evenly to obtain the pickling accelerator.

[0060] The using method of the pickling accelerator comprises the following steps: Add the pickling accelerator into the acid solution, mix evenly, and pickle the silicon steel in the acid solution added with the pickling accelerator.

[0061] The acid solution is hydrochloric acid, the pickling concentration is the concentration of hydrochloric acid, and the silicon steel is non-oriented electrical steel SWB1300, purchased from Guiwan Steel.

[0062] Performance test

[0063] 1. Reflectivity of the plate surface after pickling: Use a C84-Ⅲ type reflectivity measuring instrument to detect the reflectivity at three positions on the drive side, the middle side and the operation side of the plate surface (detect 5-6 points at each position and take the average value), and the result is the average value of the reflectivities on the drive side, the middle side and the operation side of the plate surface. The standard reflectivity > 80%.

[0064] 2. Use a Meinianda CR-10plus color difference meter to detect the plate surface, and compare the color difference ΔE between the drive side, the operation side and the middle side of the plate surface (detect 5-6 points at each position to obtain the average value), and the result is the average value of the color difference ΔE. The standard color difference ΔE of the plate surface after pickling ≤ 1.5.

[0065] 3. Silicon mud generation amount: After the pickling line runs continuously for 5 days, clean the tank, collect the silicon mud and weigh it. Divide the total weight of the silicon mud by the total amount (tons) of silicon steel pickling during this period to obtain the amount of silicon mud generated per ton of silicon steel pickled. The standard silicon mud generation amount < 0.6 kg / t of silicon steel.

[0066] 4. Silicon dioxide content in the regenerated acid: Use the ammonium molybdate spectrophotometric method to detect the silicon dioxide content in the regenerated acid. The standard silicon dioxide content in the regenerated acid < 50 ppm. The regenerated acid is the acid solution collected after pickling.

[0067] 5. Silica content in the iron oxide powder by - product of acid regeneration: Detect the silica content according to item 6 of "HG / T 2574 - 2009 Industrial Iron Oxide". The silica content in the type - I qualified iron oxide powder is ≤0.015%. The iron oxide powder by - product of acid regeneration is the iron oxide powder collected after the waste acid treatment in the acid regeneration system.

[0068] The test results are shown in Table 3.

[0069] Table 3

[0070]

[0071]

[0072] When the addition concentration of the pickling accelerator is 0, the reflectivity of the pickled plate surface is 68.9%, the color difference ΔE of the pickled plate surface is 2.2, the production amount of silicon mud is 0.67 kg / t silicon steel, the silica content in the regenerated acid is 58 ppm, and the silica content in the iron oxide powder by - product of acid regeneration is 0.028%.

Claims

1. A pickling accelerator applicable to an acid regeneration system, characterized in that The raw materials for preparation by weight percentage include: penetrant 6-17%, stripper 1-5%, dispersant 5-10%, stabilizer 1-5%, foam control agent 1-3%, and water is supplemented to 100%.

2. The pickling accelerator applicable to the acid regeneration system according to claim 1, characterized in that, The weight percentage of the stripper is 2-4%.

3. The pickling accelerator applicable to an acid regeneration system according to claim 1, wherein The weight percentage of the dispersant is 6-9%.

4. The pickling accelerator applicable to the acid regeneration system according to claim 1, characterized in that, The weight percentage of the stabilizer is 2-4%.

5. The pickling accelerator applicable to an acid regeneration system according to claim 1, wherein The penetrant includes at least one of lauryl hydroxyethyl imidazoline, heptadecenyl amine ethyl imidazoline quaternary ammonium salt, or cocoamphodiacetate disodium.

6. The pickling accelerator applicable to an acid regeneration system according to claim 2, characterized in that, The stripper includes at least one of lauryl hydroxy sulfo betaine, dodecyl dimethyl betaine, or cocoamidopropyl betaine.

7. The pickling accelerator applicable to the acid regeneration system according to claim 3, wherein The dispersant includes at least one of polyoxyethylene sorbitan monolaurate, sodium polyacrylate, or gum arabic.

8. The pickling accelerator applicable to the acid regeneration system according to claim 4, characterized in that, The stabilizer includes at least one of polyethylene glycol octyl phenyl ether or polyoxyethylene mono-tert-octyl phenyl ether.

9. The pickling accelerator applicable to the acid regeneration system according to claim 1, characterized in that, The foam control agent includes at least one of propylene glycol block polyether, polyoxyethylene polyoxypropylene block polyether, polydimethylsiloxane, or carbon alcohol defoamer.

10. A preparation method of an acid pickling promoter applicable to an acid regeneration system according to any one of claims 1-9, characterized in that, It includes the following steps: S1: Add water and start stirring, and add the penetrant under stirring conditions; S2: Then add the stripper, dispersant, stabilizer, and foam control agent in sequence, mix and stir evenly to obtain the pickling accelerator.

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