R.R. Seal II
I.-M. Chou
2003
<p><span>Metal-sulfate salts in mine drainage environments commonly occur as solid solutions containing Fe, Cu, Mg, Zn, Al, Mn, Ni, Co, Cd, and other elements. </span>Thermodynamic<span> </span>data<span> for some of the end-member salts containing Fe, Cu, Zn, and Mg have been collected and evaluated previously, and the present study extends to the system containing Ni. </span>Morenosite<span> (NiSO</span><sub>4</sub><span>-7H</span><sub>2</sub><span>O)-</span>retgersite<span> (NiSO</span><sub>4</sub><span>-6H</span><sub>2</sub><span>O) </span>equilibria<span> were determined along five humidity buffer curves </span>at<span> </span>0.1<span> </span>MPa<span> and between 5 and 22°C. Reversals along these humidity-buffer curves yield In K = 17.58-6303.35/T, where K is the </span>equilibrium<span> constant, and T is temperature in K. The derived standard Gibbs free energy of reaction is 8.84 kJ/mol, which agrees very well with the values of 8.90, 8.83, and 8.85 kJ/mol based on the vapor pressure measurements of Schumb (1923), Bonnell and Burridge (1935), and Stout et al. (1966). respectively. This value also agrees reasonably well with the values of 8.65 and 9.56 kJ/mol calculated from the </span>data<span> compiled by Wagman et al. (1982) and DeKock (1982), respectively. The temperature-humidity relationships defined by this study for dehydration </span>equilibria<span> between </span>morenosite<span> and </span>retgersite<span> explain the more common occurrence of </span>retgersite<span> relative to </span>morenosite<span> in nature.</span></p>
application/pdf
10.2138/am-2003-11-1237
en
Walter de Gruyter
Acquisition and evaluation of thermodynamic data for morenosite-retgersite equilibria at 0.1 MPa
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