Sulfides," Canadian Meta llurgical Quart erl y, Vol. 6, No. 39, pp . 333 -370. Titi-Manyaka, R., and Iwasaki , I. , 1973, "Chlorination Behaviors of Some Metal Sulfides as Investigated by Th ennogravimetric Analysis," Trans . SME ·AI ME, Vol. 254, pp . 37 -42. Titi-Manyaka , R., and Iwasaki , I. , 1976, "Chlorination Behaviors of Complex Iron, Copper and Nickel Sulfides ," T rans. SME- AIME, Vol. 260 , pp . 282 - 288 . Varley, T. , Barrett, E.P ., Stevenson, C.C.. and Bradford, R .H. , 1928, "The Chloride Volatilization Process of Ore T rea tm ent, USBM Bulletin 211. White, M.G., and White, D.M. , 1970, "Process of Treating Copper," US Patent 3,537, 961. Hydrolytic Stripping of Versatic Acid Solutions Containing Iron and Other Metals P.M. Doyle-Garner and A.J. Monhemius Abstract- Hydrolyti c st ri pping is th e process 'Whereby m etal ions in a loaded solv ent ext rac tant are hYdrolyzeq, by wa ter, typi cally at 130°C to 200°C (265 °F to 392°F). hyd rolyti c stripping tests we re on Ver sat ic 10 solutions conta ining vari ous m et als, 8lngly and in m ixtures. . Singl e sol ut ions of F e, Ni, Ou, Afg, and Mn prec ipitat ed aFetP:J. Ni(OH)f!) CutP + fU? , Mg(OH)f!) and yMntP:J. respectively, during hydro· Yhc st ri pping. Sev eral mixtures containing iron precipitat ed magnet ic spinel jerrit es, MFe tP 4- No other Comb inat ions formed m ixed oxid es. It is proposed that th e m echanisms for hydrolysis and P:eci pitation of iron in loaded Versati c solutions are to those for iron hydrolysis in aqueous solutions . agnetic inte rac ti ons betw een mixed carboxy la te Com p lexes are thought to be r esponsible for th e homogenous nucleation of magnetic mixed oxides in Preferenc e to singl eoxid es. Introduction control has b. t;!en recognized as a major problem L nYdrometallurgy.:since the electrolytic zinc process :as developed in 1916. Until the jarosite process was in- oduced 20 years ago, the zinc ferrites that form during of zinc sulfide concentrates were not leached ecause there was no su itable way of removing iron the leach liquor in a filterable form . This resulted zinc losses of 8% to 15%. Jarosites can only be PreCipitated from solutions containing sulfate ions. The and hematite process that followed are not con- In ed to sulfate solutions, so are useful for iron removal l1'u a number of other hydrometallurgical processes . W:thermore, goethite and hematite have higher tnelght percentages of iron than jarosite . They are ere fore less bulky to dispose of. n'l'h e iron residues produced in all three processes, n OWever, are contaminated with undissolved agent , and also with coprecipitated or ad- p/ bed iOnic impurities. The contaminants render the Se eCipitates unsuitable as blast furnance feed and cause },r \Tere disposal problems in many areas of the world . Of oreover, cationic impurities can lead to a serious loss lit Improved operating procedures have lowered the loss of values associated with MINFR - METALLURGICAL PROCESSING precipitation (Pammenter and Haigh , 1981) and much of the physical chemistry of iron precipitation has been elucidated (Du trizac, 1980 ). Nevertheless , it is still not possible to directly precipitate an iron product that is sufficiently pure for further use. Solvent extraction is an alternati ve to hydrolysis as a means of iron removal. In the Falconbridge matte leach process, for example , iron is removed from a chloride leach solution by extraction with tributylphosphate, which is stripped to give an iron chloride solution. However , solvent extraction merely transfers iron from one aqueous solution to another. Although a good separation of iron from the values may be achieved, iron must still be removed from the strip solution. Hydrolysis would be the most practical removal method, but would give an iron product con- taminated by the neutralizing agent and, therefore , unusable. ;Hy drolyti c stripping has already been described and proposed as a process for removing iron from loaded sol vent extractants in a saleable form: (Thorsen and Monhemius, 1979; Monhemius and Tfiorsen, 1980 ). Hydrolytic stripping is the process whereby metal ions in an organic solution are hydrolyzed by reaction with water , typically at 130"C to 2OO"C (265DF to 392DF), to precipitate an oxide or, hydroxide. The most suitable solvent extractants are ltertiary monocarboxylic acids ] such as the We rsatic acids] which possess the required acidity and 'thermal stability . For iron in solution in a carboxylic a cid extractant , HR , the hydrolytic stripping F.M. Doyle·Gamer is assistant professor of metallurgy, depart- ment of mater ials science and minerai engineering , University of California, Berkeley, CA. A.J. Monhemlus is a lecturer at the Royal Schoo l of Mines, Imperial College of Science and Technology, department of metallurgy and materials science, london, England. SME preprlnt 84-39, SME·AIME Annual Meeting , los Angeles, CA, March 1984. MMP paper 84-608. Manuscript February 1984. Discussion of this paper must be submitted, in duplicate, prior to April 30, 1985. FEBRUARY 1985 47