PARTITIONING OF NICKEL, COPPER, IRIDIUM, RHENIUM, PLATINUM, AND PALLADIUM BETWEEN MONOSULFIDE SOLID-SOLUTION AND SULFIDE LIQUID - EFFECTS OF COMPOSITION AND TEMPERATURE

Partitioning of Ni, Cu, and Pt-group elements (Ir, Rh, Pt, Pd) between monosulfide solid solution (Mss) and sulfide liquid has been investig ated in the Fe-Ni-Cu-S system at 1000 and 1100 degrees C and one atmos phere pressure. The Nernst partition coefficients (D = wt% in Mss/wt% in sulfide liquid) for Ni vary significantly from 0.19 to 1.17, while the values of D-Cu show a limited range of 0.17-0.27. The partition co efficients for Ir range from 1.06 to 13. Rhodium has a partition coeff icient slightly lower than that of Ir under the same conditions, rangi ng from 0.37 to 8.23. The partition coefficients for Pt and Pd vary fr om 0.05 to 0.16, and from 0.08 to 0.27, respectively. The partition co efficients depend strongly on the bulk S contents of the system. They increase with increasing S contents in both Mss and liquid. Platinum, Pd, and Cu behave incompatibly during Mss crystallization, strongly pa rtitioning into sulfide liquid. Nickel is incompatible in S-undersatur ated systems and S-saturated systems. It becomes compatible when the s ystem is S-oversaturated, Rhodium is compatible in S-saturated and S-o versaturated systems, but incompatible in S-undersaturated systems. Ir idium changes from highly compatible through moderately compatible to slightly compatible when the system changes from S-oversaturated throu gh S-saturated to S-undersaturated. The effect of temperature on metal partitioning is observed only in S-oversaturated systems, in which th e partition coefficients for Ni and Rh increase with decrease of tempe rature. The compatible behavior of Ir and Ph, and incompatible behavio r of Pt and Pd and Cu under S-saturated conditions appears to support the hypothesis that the observed metal zonation in many sulfide ore de posits such as Sudbury, Ontario and Noril'sk, Siberia resulted from su lfide liquid fractionation.