GB251267A - Manufacture of basic chromium salts - Google Patents

Abstract

251,267. I. G. Farbenindustrie Akt.- Ges., (Assignees of Farbwerke vorm. Meister, Lucius, & Br³ning). April 24, 1925, [Convention date]. Chrome, iron, and like mineral tanning.- Soluble double salts suitable for tanning are prepared from basic chromium salts and a salt of calcium or a metal allied to it such as magnesium, zinc, or aluminium. The process may be effected by mixing a neutral chromium salt with the other salt and adding alkali; or by mixing chromium hydroxide with the salt or the corresponding oxide and adding acid; or by adding an oxides or oxides to an acid chromium salt solution, such as that resulting from an oxidation process; or the double salt may be made during the tanning operation. In the examples ,chromium hydroxide and magnesium sulphate are treated with sulphuric acid, 100 parts of pelt being tumbled in a tanning cask with 150 parts of water and 2 parts of salt with the addiion in three portions of an amount of the double chromium salt containing 1.7-2.25 parts of chromium oxide: chromium hydroxide and magnesium chloride are treated with hydrochloric acid; chromium oxychloride is dissolved in calcium chloride solution with the aid of heat; chromium hydroxide and zinc sulphate are treated with sulphuric acid; chromium hydroxide and aluminium sulphate are dissolved in sulphuric acid; and 1000 parts of pickled pelt are treated in a tumbler with 59 parts of chromium sulphate and 52 parts of magnesium sulphate in 1500 parts of water and sodium carbonate solution containing 22.5 parts anhydrous carbonate is added. The solution of the double salt is dried for instance by evaporation in a vacuum.