Clarification process

Claim 1

In a process for clarification of an aqueous liquid wherein dispersed particles are flocculated with an insoluble metal hydroxide, the improvement which comprises adding to the liquid a water-soluble ferromagnetic organic composition selected from the group consisting essentially of ferromagnetic compositions of lignosulfonate, sulfonated tannin, and sulfonated phenol condensed with an aldehyde to associate the ferromagnetic organic composition with the metal hydroxide flocculated particles, said ferromagnetic organic composition being prepared by dissolving an iron compound in an aqueous solution of the lignosulfonate, sulfonated tannin, or sulfonated phenol condensed with an aldehyde in an amount at least twice the stoichiometric amount to react with the sulfonate groups and reacting the mixture under conditions for the formation of magnetic iron oxide in the presence of an alkali and having the iron present in ferrous and ferric states, and separating the particles from the treated liquor in the presence of a magnetic field, said ferromagnetic organic composition being added to the liquid in an amount such that the amount of the ferromagnetic composition associated with the flocculated particles imparts a sufficient magnetization to the flocculated particles for the flocculated particles to be attracted by the magnetic field.