于300℃，10MPa时测定了Fe2O3在KOH和HClO4稀溶液中的溶解度。溶解度数据分析表明，在中性-碱性热液中铁主要成Fe（OH）03和Fe（OH）-4形式存在。计算求得：300℃时，△G0FeOH03=-561.9土3.3kJ/mol，ΔG0FeOH-4=-662.7士5.0kJ/mol。在分析前人有关铁运移形式实验研究成果的基础上讨论了热液中铁的存在形式。Fe2O3， 溶解度， 中-碱性热液， 铁的存在形式。

本文于300℃，500bar时，用金袋式热液设备测定了MH（磁铁矿+赤铁矿）缓冲组合在HCl水溶液中的溶解度。计算了热水溶液中离子的活度，并用岭回归和叠代的方法处理实验数据，与多种可能的Fe存在形式模型拟合。结果表明，实验溶液中的Fe主要成FeOH+存在。求得MH组合溶解反应的平衡常数K=57.161。计算了0f,FeOH+ΔG＝260.3kJ/mol。300℃时，在地质上可能的pH和氯化物浓度条件下，热液中的Fe主要成羟络合物存在。

Na-F solutions with different pH were allowed to react under flow conditions with limestone, dolomite and siderite at 300 and 400℃ at 500 bars, in order to understand the geochemical characteristics of the interaction between rock and F-bearing hydrothermal solutions. The mineralogical and chemical composition of these carbonate rocks was studied by chemical analysis, XRD and SEM/EDAX before and after reaction with Na-F solutions. Based on an approximate thermodynamic calculation the formation of alteration phases is discussed. The pH value at room conditions and the contents of K, Na, Ca, Mg, Fe, F, SiO2 and total dissolved CO2 in solution after interaction with carbonate rocks were determined. From solution chemistry data, it is found that the amount of Na and F in the reacted solutions seemed to have roughly similar fluctuations with time, and hence, carbonate might be an effective precipitating agent for Fe in hydrothermal solutions. The present experimental study demonstrates that hydrothermal metasomatism played a very important role in the formation of the Baiyun Ebo iron deposit.

The solubility of the buffer assemblage magnetite+hematite in 0.10, 1.00 and 3.00 mol/kg NaCl solutions with various pH values was determined by use of a Dickson gold cell hydrotherma1 apparatus at 300℃ and 500 bars. Activities of H+ and Cl-in the NaCl hydrothermal solution for each determination were approximated. The experimental results show that the solubility is strongly dependent on the pH of the solutions and appears to have no explicit relation to NaCl molality in acidic solutions. The correlation of the measured solubility with pH at 300℃ suggests a change in Fe speciation in solution at pH≈5.3-5.4. Treatment of the experimental data by a ridge regressions program and an iterative procedure indicates that the dominant species in solution under the run condition are FeOH+, Fe(OH)3Cl-, Fe(OH)03 and Fe(OH)-4. Gibbs free energy of formation for these species at 300℃ and 500 bars were derived: 0ΔGf,FeOH+=-250.4 kJ/mol; ΔG0f,Fe(OH)3Cl−=-644.7 kJ/mol; ΔG0f,FeOH03=-552.6 kJ/mol; and ΔG0f,FeOH-4=-652.7 kJ/mol. The Present study demonstrates that the change in acidity of hydrothermal ore-forming solutions exerts an important influence on the transport and deposition of Fe in nature.