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Despite the availability of various reactors designed to study gas-liquid reactions, no appropriate devices are available to accurately investigate triple-phased mineral carbonation reactions involving CO gas, aqueous solutions (containing divalent cations), and carbonate minerals. This report presents a composite reactor that combines a modified conventional wetted-wall column, a pH control module, and an attachment to monitor precipitation reactions. Our test and calibration experiments show that the absorption column behaved largely in agreement with theoretical predictions and previous observations. Experimental confirmation of CO absorption in NaOH and ethanolamine supported the effectiveness of the column for gas-liquid interaction. A test run in the CO-NH-MgCl system carried out for real time investigation of the relevant carbonation reactions shows that the reactor's performance closely followed the expected reaction path reflected in pH change, the occurrence of precipitation, and the rate of NH addition, indicating the appropriateness of the composite device in studying triple-phase carbonation process.

Pyrite is the most abundant metal sulfide in the Earth’s crust and is also found on Mars. It can form by direct hydrothermal precipitation or by polymorphic phase transformation from marcasite. However, the control on the dynamics of hydrothermal pyrite precipitation is poorly understood, and the kinetics of the hydrothermal transformation from marcasite to pyrite is unknown. To address these issues, we quantified pyrite and marcasite formation in hydrothermal fluids at pH 1, using pyrrhotite as a precursor mineral to produce supersaturated solutions. In situ powder X-ray diffraction experiments at 190 °C showed that hydrothermal fluids rich in ΣS­(-II) (0.2 molal) favored the precipitation of nanocrystal pyrite (∼20 nm) due to a high saturation index (>105), while ΣS­(-II)-free fluids produced a mixture of marcasite and pyrite nanocrystals (21–46 nm) due to a low saturation index (<104). The fluid/rock ratio (70 and 120 g/g at 210 °C) can also affect the saturation indices of these fluids, influencing nucleation and crystal growth dynamics of pyrite and marcasite and resulting in complex evolution of crystallite size, phase abundance, and the pyrite/marcasite ratio. Ex situ hydrothermal experiments at 210 °C showed rapid transformation from marcasite to pyrite, with around 95% marcasite being transformed to pyrite in 20 weeks, compared to more than 6.3 million years at 210 °C under dry conditions based on extrapolation from previous kinetic studies. These results suggest that saturation index influences hydrothermal precipitation dynamics and controls phase selection between pyrite and marcasite and that marcasite may not survive over geological time in low-temperature (<200 °C), water-saturated environments.

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Water-cut detection of crude oil based on capacitive sensors and conductivity sensors are widely used in practice. However, the above two methods cannot achieve full-scale measurement of water-cut of crude oil. Besides, their measurement accuracy is sensitive to temperature, which greatly limits their application. A novel method of crude oil water-cut detection based on multi-sensor fusion is proposed in the paper. The proposed method uses a capacitive sensor and a conductivity sensor to measure the crude oil separately, and uses a temperature sensor to compensate the measurement result at the same time. Finally, the proposed method introduces a neural network for data fusion to predict the water content. The experiment results show that the proposed multi-sensor fusion technique performs better than capacitance and conductivity technique. The accuracy of this method is higher than single capacitance or conductivity method. When the water content is lower than 3%, the prediction error is less than 0.1%. When the water content is in a range from 3% to 10%, the prediction error is less than 0.5%. When the water content is in a range from 10% to 100%, the prediction error is less than 1.5%.