Other
Scientific paper
Apr 1988
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1988gecoa..52..813b&link_type=abstract
Geochimica et Cosmochimica Acta, vol. 52, Issue 4, pp.813-820
Other
Scientific paper
Sphalerite and galena solubilities have been experimentally determined under H 2 S-saturated conditions over the 3-5 molal (=m) NaCl range and for temperatures up to 95°C. Both ZnS and PbS are about 5 times more soluble in 5 m than in 3 m NaCl brines. ZnS is more soluble than PbS by factors of 30-100 over the experimental conditions investigated. Some representative molal solubilities at pH = 2, based on the best-fit solubility isotherms, are: 3 m NaCl, 80° C : [ Zn ] = 10 -3.25 , [ Pb ] = l 0 -5.10 ; 4 m NaCl, 80° C : [ Zn ] = l 0 -2.86 , [ Pb ] = 10 -4.75 ; 5 m NaCl, 80° C : [ Zn ] = 10 -2.55 , [ Pb ] = 10 -4.46 . An increase in temperature of only 15°C produces a solubility increase comparable to or greater than that produced by the 3 to 5 m NaCl increase: 5 m NaCl, 95° C : [ Zn ] = 10 -1.93 , [ Pb ] = 10 -3.71 . The difference in the solubilities of ZnS and PbS decreases with increasing temperature. Using recent literature values for the stability constants of the chloride complexes of Zn and Pb up to 300°C, we have calculated ZnS and PbS solubilities over the 25-300°C and 1-5 m NaCl range. ZnS is consistently more soluble than PbS over this range of conditions, with the difference in molal solubilities ranging from at least two log units at 25°C to at least one log unit at 300°C. For temperatures below 100°C, the results can be compared with the experimental ZnS and PbS solubilities obtained under H 2 S-saturated conditions. Agreement is very good at 60° to 95°C and all NaCl molalities; at 25°C the calculated solubilities are low by up to one log unit. Field data from various geothermal systems have been used to calculate equilibrium solubilities of sphalerite and galena in these systems. High-salinity brines appear to range from supersaturated (Salton Sea, high-temperature) to strongly supersaturated (Red Sea, low temperature) with respect to these sulphides. By contrast, high-temperature seawater-salinity solutions at sediment-free spreading axes are grossly undersaturated in sphalerite and galena. The latter situation is of interest in that massive sulphide deposits are nevertheless forming from such solutions. On the other hand, vent fluids depositing sulphides at the sediment-covered axis in the Guaymas Basin appear to be near saturation in sphalerite and galena. This is probably related to the higher pH of these fluids, and the higher metal contents of the underlying sediments relative to basalts. Calculated solubilities for on-land geothermal systems (high temperature, seawater to near-meteoric salinity) yield values in reasonable agreement (<0.2 log units) in two of three cases.
Anderson Malcolm G.
Barrett T. J.
No associations
LandOfFree
The solubility of sphalerite and galena in 1-5 m NaCl solutions to 300°C does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The solubility of sphalerite and galena in 1-5 m NaCl solutions to 300°C, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The solubility of sphalerite and galena in 1-5 m NaCl solutions to 300°C will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-848885