Simultaneous Partitioning of Divalent Metal Ions between Alabandite and 1 mol/L (Ni, Mg, Co, Zn, Fe)Cl2 Aqueous Solutions under Supercritical Conditions

To clarify the element partitioning behavior between minerals and aqueous chloride solutions, we conducted experiments to investigate simultaneous partitioning of Ni2+, Mg2+, Co2+, Zn2+, Fe2+, and Mn2+ ions between alabandite (MnS) and 1 mol/L (Ni, Mg, Co, Zn, Fe)Cl2 aqueous solutions at 500–800 °C and 100 MPa. The bulk partition coefficients calculated using the following equation were in the order of Fe2+ > Co2+ > Ni2+ ≈ Zn2+ > Mn2+ >> Mg2+; KPN = (xMeS/mMeaq)/(xMnS/mMnaq). A partition coefficient-ionic radius (PC-IR) curve was plotted with the logarithmic value of the partition coefficient on the y-axis and the ionic radius at the six-fold coordinated site on the x-axis. The peak of this curve was located near the ionic radius of Fe2+ and not near the ionic radius of Mn2+. Zn2+ showed a slight negative partitioning anomaly, which increased in the order of sulfide minerals < arsenic sulfide minerals < arsenide minerals as the covalent bond became stronger. Ni2+ showed a positive partitioning anomaly, which indicated that it preferred an octahedral structure. The width of the PC-IR curve decreased in the order of sulfide minerals > arsenic sulfide minerals > arsenide minerals as the covalent bond became stronger, that is, the ion selectivity became stronger

Chemical Compositional Signatures of Constituent Minerals of Iron Slags and Ores from the Khmer Monuments

Iron slags and ores were collected from 22 sites (A to V) in Preah Khan of Kompong Svay, the area surrounding Phnom Daek, and the Angkor monuments. Iron ores were taken from two outcrops in Phnom Daek. The chemical compositions of fayalite and wüstite in the iron slags and magnetite in the iron ores were determined using a scanning electron microscope equipped with an energy dispersive spectrometer. Cluster analysis and principal component analysis using averaged chemical compositional data for fayalite allowed for the investigated slag dumps to be classified into two main groups: Groups 1 and 2. The slag dumps in the area surrounding Phnom Daek and those in the Angkor monuments were classified as Group 1, and those in Preah Khan of Kompong Svay were classified as Group 2, except for sites C and U, which were classified as Group 1. Radiocarbon dating was carried out on 10 charcoal fragments from slag dumps outside the Angkor area. The dating results indicate that iron making in Preah Khan of Kompong Svay was conducted in and after the 13th century except for sites C and U, where iron ores may have been supplied from Phnom Daek before the 13th century