Improvements in or relating to processes for the pickling of metals and the like processes

摘要

Mono-mercaptans of the class R-SH where R represents a hydrocarbon radical or an anthraquinonyl group, either of which may contain one or more of alkyl, amino or alkoxyl groups but no other substituents, are used as acid inhibitors. Thiophenol, thio-beta-naphthol, benzyl mercaptan, isoamyl mercaptan, isopropyl mercaptan and amino-substituted mercaptans e.g. 2-amino-5-ethoxy-thiophenol and 1-mercapto-2-aminoanthraquinone are referred to and may be mixed with wetting or dispersing agents such as cellulose sulphite pitch, Turkey red oil, Twitchell's reagent, aldehyde condensation products of naphthol sulphonic acids, petroleum sludge acids, aldehydes, carbohydrates, &c. Dispersion may also be effected by adding the inhibitor as a solution in concentrated acid. To prevent slowing-up of the action when pickling in dilute sulphuric acid metal chlorides, e.g. sodium chloride, may be added to the bath either separately or mixed with the inhibitor. The following inhibitors are also referred to:--mouldy flour, size or glue, sulphonation products of slaughterhouse waste, acid extracts of coal, sludges from sulphuric acid treatment of coal tar or petroleum, carbazole, pyridine, aniline and quinoline.ALSO:Mono-mercaptans of the class R-SH where R represents a hydrocarbon radical or an anthraquinonyl group, either of which may contain one or more of alkyl, amino, or alkoxyl groups but no other substituents, are used as acid inhibitors in pickling baths, in the removal of rust from the interior of piping or in any case in which it is desired to remove rust without injury to the surface of the metal. Thiophenol, thio-beta-naphthol, benzyl mercaptan, isoamyl mercaptan, isopropyl mercaptan, and amino-substituted mercaptans e.g. 2-amino-5-ethoxythiophenol and 1-mercapto-2-amino anthraquinone are referred to and may be mixed with wetting or dispersing agents such as cellulose sulphite pitch, Turkey Red oil, Twitchell's reagent, aldehyde condensation products of naphthol sulphonic acids, petroleum sludge acids, aldehydes, carbohydrates, &c. Dispersion may also be effected by adding the inhibitor as a solution in concentrated acid. To prevent slowing-up of the action when pickling in dilute sulphuric acid metal chlorides, e.g. sodium chloride, may be added to the bath either separately or mixed with the inhibitor. The following inhibitors are also referred to:-mouldy flour, size or glue, sulphonation products of slaughter-house waste, acid extracts of coal, sludges from sulphuric acid treatment of coal tar or petroleum, carbazole, pyridine, aniline, and quinoline.