Patent GB-477425-A (GB)
Title: Improvements in or relating to pickling metal, particularly ferrous metal
IPC: C23G1/06
Filed: 1936-08-26
Abstract: Metal, particularly ferrous metal, is pickled in a bath of mineral acid, e.g. dilute sulphuric acid, to which has been added as an inhibitor a small quantity of a product obtained by sulphonating a mixture of an organic hydroxylic compound and a mustard oil or a substituted thiourea.  The hydroxylic compound may be ethyl alcohol, phenol, cresol, creosote, glycerine, or sulphonated castor oil and this may be mixed with, for example, phenyl or diphenyl thiourea, or phenyl or allyl mustard oil. Preferably, about half of the hydroxylic compound is first sulphonated with excess of concentrated sulphuric acid, the temperature being kept low, usually below 100 DEG  F., by adding the hydroxylic compound slowly, stirring, and cooling.  The mixture of the other half of the hydroxylic compound and the mustard oil or substituted thiourea is then added, the same conditions being observed.  The preferred mixture is commercial creosote and thiocarbanilide, 8--10 gallons of the creosote being added to 30 gallons of 66 DEG  B<\>e. sulphuric acid, followed, when sulphonation is complete, by the addition of a mixture of 5--7 gallons of creosote and 53 pounds of thiocarbanilide.  The inhibitor is preferably added to concentrated mineral acid which is then diluted to form the pickling bath.  Mixtures of 1 /5 mol. of sulphonated castor oil with 1 mol. of phenyl mustard oil or thiocarbanilide and of 1 mol. of thiocarbanilide with 2 mols. of ethyl alcohol, phenol or cresol are also referred to as mixtures suitable for sulphonation.ALSO:Metal, particularly ferrous metal, is pickled in a bath of mineral acid, e.g. dilute sulphuric acid, to which has been added as an inhibitor a small quantity of a product obtained by sulphonating a mixture of an organic hydroxylic compound and a mustard oil or a substituted thiourea.  The hydroxylic compound may be ethyl alcohol, phenol, cresol, creosote, glycerine, or sulphonated castor oil, and this may be mixed with, for example, phenyl or diphenyl thiourea, or phenyl or allyl mustard oil. Preferably about half of the hydroxylic compound is first sulphonated with excess of concentrated sulphuric acid, the temperature being kept low, usually below 100 DEG  F., by adding the hydroxylic compound slowly, stirring, and cooling.  The mixture of the other half of the hydroxylic compound and the mustard oil or substituted thiourea is then added, the same conditions being observed.  The preferred mixture is commercial creosote and thiocarbanilide, 8--10 gallons of the creosote being added to 30 gallons of 66 DEG  B<\>ae. sulphuric acid, followed, when sulphonation is complete, by the addition of a mixture of 5--7 gallons of creosote and 53 pounds of thicoarbanilide.  The inhibitor is preferably added to concentrated mineral acid which is then diluted to form the pickling bath.  Mixtures of \ba1/5\be mol. of sulphonated castor oil with 1 mol. of phenyl mustard oil or thiocarbanilide and of 1 mol. of thiocarbanilide with 2 mols. of ethyl alcohol, phenol of cresol are rlso referred to as mixtures suitable for sulphonation.  Details are given of the effects of pickling baths with and without inhibitor on low carbon steels and on a high carbon steel containing about 0,7 per cent carbon, about 1 per cent chromium, and about 0,2 per cent molybdenum.ALSO:Metal, particularly ferrous metal, is pickled in a bath of mineral acid, e.g. dilute sulphuric acid, to which has been added as an inhibitor a small quantity of a product obtained by sulphonating a mixture of an organic hydroxylic compound and a mustard oil or a substituted thiourea.  The hydroxylic compound may be ethyl alcohol, phenol, cresol, creosote, glycerine, or sulphonated castor oil and this may be mixed with, for example, phenyl or diphenyl thiourea, or phenyl or allyl mustard oil. Preferably about half of the hydroxylic compound is first sulphonated with excess of concentrated sulphuric acid, the temperature being kept low, usually below 100 DEG  F., by adding the hydroxylic compound slowly, stirring, and cooling.  The mixture of the other half of the hydroxylic compound and the mustard oil or substituted thiourea is then added, the same conditions being observed.  The preferred mixture is commercial creosote and thiocarbanilide, 8-10 gallons of the creosote being added to 30 gallons of 66 DEG  B<\>ae. sulphuric acid, followed, when sulphonation is complete, by the addition of a mixture of 5-7 gallons of creosote and 53 pounds of thiocarbanilide.  The inhibitor is preferably added to concentrated mineral acid which is then diluted to form the pickling bath.  Mixtures of 1/5 mol. of sulphonated castor oil with 1 mol. of phenyl mustard oil or thiocarbanilide and of 1 mol. of thiocarbanilide with 2 mols. of ethyl alcohol, phenol, or cresol are also referred to as mixtures suitable for sulphonation. Details are given of the effects of pickling baths with and without inhibitor on low carbon steels and on a high carbon steel containing about 0,7 per cent carbon, about 1 per cent chromium, and about 0,2 per cent molybdenum.