Process for isolating sulphur dyestuffs from aqueous crude melts containing sodium polysulphide

In the process for isolating solid sulphur dyestuffs from crude sulphur dyestuff melts, the improvement comprises adding 10.sup.-4 to 1% by weight, relative to the amount of dyestuff, of an organic flocculating auxiliary to the crude dyestuff melt to produce a filterable dyestuff precipitate and then separating said precipitate wherein the organic flocculating auxiliary is a polymer or copolymer containing monomeric units selected from the group consisting of acrylic acid, methacrylic acid, alkali acrylate, alkali methacrylate, acrylamide, methacrylamide, amino alkyl acrylate having 2 to 4 alkyl carbon atoms, amino alkyl methacrylate having 2 to 4 alkyl carbon atoms, N-methylamino alkyl acrylate having 2 to 4 alkyl carbon atoms, N-dimethylamino alkyl acrylate having 2 to 4 alkyl carbon atoms, N-methylamino alkyl methacrylate having 2 to 4 alkyl carbon atoms, quaternized amino alkyl acrylate having 2 to 4 alkyl carbon atoms, quaternized amino alkyl methacrylate having 2 to 4 alkyl carbon atoms, quaternized N-methylamino alkyl acrylate having 2 to 4 alkyl carbon atoms, quaternized N-dimethylamino alkyl acrylate having 2 to 4 alkyl carbon atoms, quaternized N-methylamino alkyl methacrylate having 2 to 4 alkyl carbon atoms, quaternized N-dimethyl alkyl methacrylate having 2 to 4 alkyl carbon atoms, ethylene oxide, ethylene imine and their saponification products.