Solubility of Iron Sulfides

Information is presented on the forms in which iron sulfides deposit from aqueous solutions, on how solubility changes with temperature and composition of the solution, and on the kinetics and mechanism for formation and dissolution. The solubilities to be evaluated are divided into: solubility of iron sulfides in water to which only acid or base is added; and the solubility of iron sulfides in water to which other sulfide (H2S, NaHS, etc.) and acid or base is added. Using normal chemical concepts of ionic equilibrium and its shift with ionic concentrations and temperature, and the limited data available, predicted magnitudes and changes of concentration are calculated and compared with existing values. The amount of iron which can remain in solution with H2S present is shown to be temperature-sensitive. (N.W.R.)