Lead-copper-sulfur system

This value leads to AfG(H2AsS20"(aq)) = -244.4 kJ mol. Clarke and Helz (20(X)) analyzed phase behavior in the copper + arsenic + sulfur-i- water system and obtained a somewhat different value for the equilibrium constant for eq 11. They obtained p/f = -8.23 0.32. This value leads to AfG(H2AsS20 (aq) = -242.5 kJ-mol. The minimum uncertainty in this value, and presumably the immediately previous value is at least 1.8 kJ-mol. We took the former value that arose solely from the treatment of Eary s solubility determinations over those obtained in the mixed arsenic -i-copper aqueous sulfidic system, because of difficulties in establishing the activity of arsenic sulfide in the latter system. 

The upper temperature limits for bulk sulfiding of various metals in this reaction system model are listed in Table II. The upper temperature limit is defined as the temperature above which metal sulfiding does not occur. Unless otherwise noted, the form of metal sulfide incorporated into the model was MeS, i.e. the monosulfide. On this basis, with a catalyst operating at 538°-815°C, bulk sulfiding is likely to occur with copper, iron, zinc, lead, and ruthenium. However, it has been our experience that used base metal catalysts usually contain less sulfur than a few tenths of one wt % therefore, bulk sulfiding does not occur. 

The nanocrystalline semiconductors, PbS and CuS, were prepared by y-irradiation at room temperature in an ethanol system by Qiao et al. (1999). Carbon disulfide was used as the sulfur source lead acetate and copper chloride were used as metal ion sources. The purity and compositions of the products were examined by x-ray photoelectron spectroscopy. The photoluminescence property of as-prepared PbS was further studied. A blue shift observed in the PL spectra indicated the quantum size effect on nanocrystalline PbS. 

Most pyrometallurgical processes are performed at temperatures high enough to ensure that all the possible reactions proceed very fast, but occasionally this is not so, and therefore the equilibrium condition of the system may not be optimal for the yield of a desired product of reaction. This is the case for the removal of copper from primary lead by reaction with elemental sulfur. It is highly desirable to know and understand this, in order to be able to specify the optimum conditions for the conduct of the process - in this case, known as decopperising, or fine decoppering or sulfur drossing. 

For permanent storage the trap J containing the solid sulfur(VI) fluoride is connected through a ground joint to a metal system employed in transferring the contents to a steel cylinder. This metal system (conveniently made of copper or bronze) consists of a manifold tube leading from... 

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