Kinetic Study on the Chemical and Isotope Exchange Reactions Between Aqueous Solutions and Solid Compounds.

本研究的主要目的是开发一种新的实验方法，用于研究在广泛的温度和压力范围内矿物和溶液之间反应的动力学。我们开发了三种新的实验方法和设备，远远优于以前的研究者使用的。第一种是利用差示干涉显微镜和化学滴定原理的原位观察方法；新开发的实验设备适用于研究各种固体（有机和有机）和溶液（水和非水）之间的反应，温度高达300^ C，压力高达200 bar。利用该实验装置研究了石膏、硝酸钡、k -明矾和CdI_2在25^ C水溶液和25^ C -200^ C水溶液中溶解/生长的动力学参数（反应速率、机理、溶解度等）。另一项新进展是用高温光谱学方法测定水溶液与固体化合物反应时的形态。该方法成功地应用于PbS-NaCI-H_2O体系中，温度范围为25^ ~ 350^ C。第三个新发展是应用硫水解反应来控制流体的氧化还原状态，这对于研究涉及氧化还原反应的矿物和溶液的反应动力学至关重要。该方法成功地测定了金、黄铁矿在250^ 350^ C水溶液中的反应速率和溶解度。对反应产物的硫同位素组成进行了分析；这些数据被用来获得高温下水相间氧化还原反应的动力学信息。上述调查结果以及本项目其他研究获得的结果，是确立地壳和水圈中重要元素迁移和积累规律的重要步骤。少

The primary objective of this research was to develop a new experimental method for studies of the kinetics of reactions between minerals and solutions over a wide range of temperature and pressure. We have developed three new experimental methods and facilities, which are far superior to those used by previous investigators. The first one is an in situ observation method using a differential interference microscope and the principle of chemical titration ; the newly developed experimental facility is applicable to studies on reactions between a variety of solids (both organic and in organic) and solutions (both aqueous and non-aqueous) at temperatures upto-300^ﾟC and pressures up to-200 bars. The new experimental facility was used to determine the various kinetic parameters (reaction rates, mechanisms, solubility, etc.) governing the dissolution/growth of gypsum, barium nitrate, K-alum, and CdI_2 in aqueous solutions at 25^ﾟC, and barite in aqueous solutions at 25^ﾟ-200^ﾟC. The second … More new development is a high temperature photospectroscopic method for determination of the speciation of aqueous solutions during reactions with a solid compound. This method was successfully applied to the PbS-NaCI-H_2O system in the temperature range of 25^ﾟ to 350^ﾟC. The third new development is an application of the sulfur hydrolysis reaction to control the redox state of fluids, which is essential for studies on reaction kinetics of a mneral and solution involving redox reactions. This method was successfully applied to determine the reaction rates and the solubilities of gold and pyrite in aqueous solutions at 250^ﾟ-350^ﾟC. The reaction products from these experiments were analyzed for the sulfur isotopic compositions ; these data were used to obtain kinetic information on the redox reactions among aqueous species at high temperatures. The results of investigations described above, and those obtained from other studies in this project, are important steps toward establishing the principles governing the migration and accumulation of important elements in the Earth's crust and in the hydrosphere. Less