Abstract Vaterite-type calcium carbonate particles have some unique properties such as high hydrophilicity, large surface areas, and hierarchical structures consisting of primary vaterite particles in comparison with calcite or aragonite-type polymorphs. In this paper, gypsum (CaSO4·2H2O) suspension is used to synthesize micro-sized vaterite CaCO3 through magnetic stirring (MS) and ultrasonic probe vibration (UPV) methods. The effects of ammonia concentration, CO2 flow rate, solid-liquid ratio on the gypsum carbonation process, mineral phase composition, morphology and particle size distribution of CaCO3 are investigated. The results show that the carbonation process is significantly influenced by ammonia concentration, CO2 flow rate and ultrasound. Comparing with magnetic stirring, ultrasonic probe vibration take less time to reach the complete carbonate reaction. Gypsum is transformed to vaterite with the conversion rate about ∼95% when the mole ratio of NH4+/Ca2+ is 2.4 otherwise the carbonation reaction was uncompleted with gypsum residues left. Comparing with MS method, the UPV method resulted in smaller size and narrower size distribution of as-prepared microparticles and approximately 80% reduction of the particle size was achieved. It is established that increasing the solid-liquid ratio resulted in larger particle size in MS system and smaller particle size in UPV system. Increasing CO2 flow rate caused the particle size decreased in MS system and increased in UPV system.

中文翻译：

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超声探头振动/磁力搅拌在石膏悬浮体系中高产合成球霰石微粒

摘要 球霰石型碳酸钙颗粒与方解石或文石型多晶型物相比，具有亲水性高、比表面积大、原生球霰石颗粒呈分级结构等特点。本文采用石膏（CaSO4·2H2O）悬浮液，通过磁力搅拌（MS）和超声探头振动（UPV）方法合成了微球球霰石CaCO3。研究了氨浓度、CO2 流量、固液比对石膏碳酸化过程、CaCO3 矿物相组成、形貌和粒度分布的影响。结果表明，碳酸化过程受氨浓度、CO2 流速和超声波的显着影响。与磁力搅拌相比，超声波探头振动达到完全碳酸盐反应所需的时间更短。当 NH4+/Ca2+ 的摩尔比为 2.4 时，石膏转化为球霰石的转化率约为 95%，否则碳酸化反应未完成，残留石膏残留物。与 MS 方法相比，UPV 方法导致制备的微粒的尺寸更小，尺寸分布更窄，并且实现了约 80% 的粒径减小。已经确定，增加固液比导致 MS 系统中更大的粒径和 UPV 系统中更小的粒径。增加 CO2 流速导致 MS 系统中的粒径减小，而 UPV 系统中的粒径增加。4 否则碳酸化反应未完成，残留石膏。与 MS 方法相比，UPV 方法导致制备的微粒更小尺寸和更窄的尺寸分布，并且实现了大约 80% 的粒径减小。已经确定，增加固液比导致 MS 系统中更大的粒径和 UPV 系统中更小的粒径。增加 CO2 流速导致 MS 系统中的粒径减小，而 UPV 系统中的粒径增加。4 否则碳酸化反应未完成，残留石膏。与 MS 方法相比，UPV 方法导致制备的微粒的尺寸更小，尺寸分布更窄，并且实现了约 80% 的粒径减小。已经确定，增加固液比导致 MS 系统中更大的粒径和 UPV 系统中更小的粒径。增加 CO2 流速导致 MS 系统中的粒径减小，而 UPV 系统中的粒径增加。已经确定，增加固液比导致 MS 系统中更大的粒径和 UPV 系统中更小的粒径。增加 CO2 流速导致 MS 系统中的粒径减小，而 UPV 系统中的粒径增加。已经确定，增加固液比导致 MS 系统中更大的粒径和 UPV 系统中更小的粒径。增加 CO2 流速导致 MS 系统中的粒径减小，而 UPV 系统中的粒径增加。