LAUSR

A reliable anoxic plug flow reactor has been developed to study iron sulfide (FeS) precipitation kinetics, solubility, and phase transformation simultaneously. The effects of temperature (23–125 °C), ionic strength (0.00886–5.03 mol/kg), and ferrous iron [Fe(II)] to sulfide [S(-II)] concentration ratio (1:20 to 1:5) were studied. The kinetics of FeS precipitation was found to be a pseudo-first-order reaction with respect to Fe(II) concentration, when Fe(II) concentration is significantly lower than the S(-II) concentration. FeS precipitation kinetics can be accelerated by high temperature and high ionic strength but not be affected by the Fe(II) to S(-II) concentration ratio at the tested ratio range. A model for predicting FeS solubility and precipitation was developed by using FeS solubility data measured in this study and data from literature. At a temperature ≤100 °C, freshly precipitated FeS was found to be mackinawite. Mackinawite can transform to troilite at a temperature ≥50 °C, and low ionic stre...