A New Addition Agent for the Electrolytic Refining of Tin and Lead

Hexanol‐3 tails, phenol coefficient 16, was found to be an excellent addition agent for the electrolytic refining of tin from a stannous sulfate‐sulfuric acid electrolyte, 1.93 lb. (0.88 kg.) being required per ton of tin refined. In the electrolytic refining of lead from the fluosilicate bath, 0.8 lb. (0.36 kg.) is required per ton of metal refined. Hexanol‐3 tails is a complex mixture containing phenolic compounds that remains after the higher tar acids have been removed from certain coal tar distillation fractions. These impure mixtures of aromatic hydroxy compounds of the higher homologs of phenol are better addition agents than the corresponding pure compounds or mixtures of pure compounds. A method was developed for maintaining a desirable concentration of a slightly soluble addition agent in the bath by keeping a solution of the addition agent in a heavy insoluble liquid in the bottom of the bath.