SU1534096A1 - Composition for pickling carbon steels - Google Patents

Abstract

This invention relates to the field of chemical etching of metals, namely, compositions for etching carbon steels. The aim of the invention is to increase the degree of protection of the metal against acid corrosion and waste disposal. The composition for pickling carbon steels contains, wt%: hydrochloric acid 30% concentration 46.0-73.0

formaldehyde 2.0-3.85

4-oxyacetophenone 0.1-0.54

4-hydroxy-3-hydroxymethyl acetophenone 0.1-0.46

4-hydroxy-3-chloromethylacetophenone 0.05-0.38

tar and condensation products 0.25-0.92

acetic anhydride 1.15-4.00 and acetic acid else. Increasing the degree of metal corrosion protection and waste disposal is achieved through the use of hydrochloric acid and inhibiting additives in the form of the mother liquor from the production of the drug salbutamol, including hydrochloric acid, formaldehyde, 4-hydroxy-acetophenone, 4-hydroxy-3-hydroxymethyl acetophenone, 4 -oxy-3-chloromethylacetophenone and the products of tarry and condensation, and in the form of distant acetic acid from the production of the same preparation, including acetic anhydride and acetic acid, when the ratio of mother liquor and distant acetic acid 1.0: (0.3-1.0). 2 tab.

Description

The invention relates to chemical etching of metals, namely, compositions for etching carbon steels, and can be used in acid etching of metal surfaces in preparing it for the application of coatings for acid cleaning of heat exchangers in heat and power engineering, metallurgy, mechanical engineering and in chemical industry. .

The aim of the invention is to increase the degree of protection of the metal against acid corrosion and waste disposal.

Example. For experimental verification of the proposed composition, compositions with different ratios of components are prepared by mixing them.

To determine the degree of protection of metals against corrosion, etching of samples from St 10 with a layer of scale and the proposed solution was carried out at 80 ° C for 40 minutes.

The results of the tests are presented in Table 1.

The etching composition contains a mixture of acidic wastes from the production of a medicinal product salbutamol: mother liquor from the stage of preparing 4-hydroxy-3-chloromethylacetophenone and distant acetic acid from the stage of preparing 4-acetoxy-3-acetoxymethyl acetophenone taken in ratios 1: (0.3-1).

In the manufacture of the drug, salbutamol produces a large amount of concentrated acid waste. At the stage of synthesis of 4-hydroxy-3-chloromethylacetophenone, a waste mother liquor of the following composition is obtained, wt%: 30% hydrochloric acid 95-92

Organic substances 5-8 Among the identified organic compounds in the mother solution are contained,%: formaldehyde 4-5; 4-oxyacetophenone 0.2-0.7; 4-hydroxy-3-hydroxymethyl acetophenone 0.2-0.6; 4-hydroxy-3-chloromethoxy-acetophenone 0, 1-0, 5. In addition, in the solution there are products of tar and condensation of these substances in the amount of 0.5-1.2%. The mother liquor is a thin dark colored liquid. When it is stored at room temperature, after 1-2 days, a resinous brown precipitate is formed, which is formed due to the further course of the tar and condensation processes.

In the step of preparing 4-acetoxy-3-acetoxymethyl acetophenone, distant acetic acid is obtained containing 92-95% acetic acid and 8-5% acetic anhydride.

When mixing the mother liquor and distant acetic acid in a ratio of 1: (0.3-1.0), the stability of the resulting solution increases during storage up to 6 months, the separation of a resinous precipitate is prevented and the properties of the pickling solution are preserved - the rate of descaling from the metal surface is high and a high degree of metal protection.

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The composition of the components and the properties of the proposed composition are presented in Table 2.

The proposed composition with an optimal ratio of the stock solution and distilled acetic acid 1.0: (0.3-1.0) has a high degree of metal protection of 99.2-99.5%, provides a high rate of descaling during etching. During prolonged storage (for 6 months), the appearance of the composition does not change and high protective properties are preserved.

The use of the proposed composition makes it possible to significantly reduce metal loss during etching, to obtain a metal surface of good quality, which ensures the application of better coatings and increases the time between overhauls of heat exchange equipment and, consequently, its durability.

Claims (1)

Invention Formula A composition for pickling carbon steels, containing hydrochloric acid and inhibiting additives, characterized in that it contains hydrochloric acid and inhibiting additives in the form of a mother liquor from the production of the drug salbutamol in order to increase the degree of protection of the metal from acid corrosion and waste disposal. including hydrochloric acid, formaldehyde, 4-hydroxy-acetophenone, 4-hydroxy-3-hydroxymethyl-acetophenone, 4-hydroxy-3-chloromethoxy-acetophenone and the products of tar and condensation, and in the form of distilled acetic acid from Dstva the same drug, including acetic anhydride and acetic acid, with a ratio of mother liquor and distant acetic acid 1.0: (0.3-1.0) in the following ratio of components, wt.%: Salt on acid 30% 0 concentration Formaldehyde 4-Oxyacetophenone 4-hydroxy-3-hydroxymethyl acetophenone 4-Oxy-3-chloromethoxy- acetophenone Pitch products and condensation Acetic anhydride Acetic acid 46.0-73.0 2.0-3.85 0.1-0.54 0.1-0.46 0.05-0.38 0.25-0.92 1, 15-4.00 Else. T a fi l and c I , 0 0.3 Hydrochloric acid 0.33 g / l, sulfuric acid 1.0 g / l; VAT residue 1,4-butanediol 0.04 g / l, f table 2 Characteristics of the solution The ratio of the mother liquor and distant acetic acid Component content, wt.%: hydrochloric acid 30% conc. formaldehyde A-oxyacetophenone 4-hydroxy-3-hydroxymethyl acetophenone 4-hydroxy-3-chloromethoxyacetophenone pitch products and condensation acetic anhydride acetic acid Time of descaling, min. The degree of metal protection,% after 14 days. storage 99.5 Uniform solution for 6 months. Same storage 15 99.4 Indicators for composition Iiii , 0: 0.3 1.0: 0.75 1.0: 1.0