The use of molten salt hydrates in metallurgical processing

拟议的项目旨在更好地了解熔盐水合物及其在矿物和金属加工方面的潜在应用。 熔融盐水合物（MSH）是对水具有高亲和力的化合物，因此形成具有一定范围的熔点和水合度的水合物，这取决于每种盐的温度和湿度。 一些例子是MgCl 2-XH 2 O和FeSO 4-XH 2 O，其中X是缔合沃茨的数量。 迄今为止，有关盐的研究工作通常分为两大阵营：水相和无水相。 含水体系是水与盐的比例非常高的体系，而无水体系仅由盐（熔融盐）组成。 这项工作旨在调查这两个非常不同的阶段之间的区域。 当然，随着水化程度的微小变化（即2.1摩尔水对1.9摩尔水），MSH的水活性将发生显著变化。 这种现象可以加以利用。 通过更好地了解MSH，应该可以研究矿物和金属加工中的广泛潜在应用。 其中一些主题是：- 气体吸收：一些MSH可逆地吸收大量的气体，如CO2和SO2，打开了它们在烟道气清洁或气体分离中使用的可能性。 在这项工作中，将在一定范围的MSH（盐、温度、水合作用）内确定各种气体的溶解度，以生成用于建模目的的足够数据。 考虑的气体包括CO2、SO2、H2S和HCl。- 水解：考虑到可获得的高温，可以水解MSH中的金属离子;例如，可以从含金属氯化物的MSH获得有价值的金属氧化物粉末。- 热储存：可逆地添加蒸汽可以释放MSH的相当大的水合热，为HVAC和太阳能热能应用提供热存储/冷却。 更传统的显热储存也是一种选择。- 浸出：MSH中的酸活性远高于稀溶液。 因此，热的MSH可以作为溶解难熔矿物的“超级澄清剂”。 在初步的氯化物浸出试验中已经证明了这一点，但这种效果的机理和最佳条件还没有清楚地了解。

The proposed projects are aimed at better understanding molten salt hydrates and their potential applications to mineral and metal processing.  Molten salt hydrates (MSHs) are compounds that have a high affinity to water and so form hydrates that have a range of melting points and degrees of hydration, depending on the temperature and humidity, for each salt.  Some examples are MgCl2-XH2O and FeSO4-XH2O, where X is the number of associated waters.   To date, research work concerning salts has typically been divided into two camps: aqueous, and anhydrous.  Aqueous systems are those with a very high ratio of water to salt, and anhydrous systems consist of only salt (molten salts).  This work seeks to investigate the region between these two very different phases.  Certainly, there will be a significant shift in water activity with MSHs with a small change in the degree of hydration (i.e. 2.1 moles of water versus 1.9 moles).  This phenomenon could be exploited.  Through a better understanding of MSHs, it should be possible to investigate a wide range of potential applications in mineral and metal processing.  Some of these topics are: - Gas absorption:  Some MSHs reversibly absorb large amounts of gases such as CO2 and SO2, opening the possibility for their use in flue gas cleaning, or gas separation.  For this work, solubility of various gases would be determined over a range of MSHs (salt, temperature, hydration) to generate sufficient data to be used for modelling purposes.  Gases for consideration include CO2, SO2, H2S, and HCl. - Hydrolysis:  Given the high temperatures obtainable one could hydrolyse metal ions in the MSH; for example it might be possible to obtain valuable metal oxide powder from a metal chloride-bearing MSH. - Thermal storage:  Reversibly adding steam can release an MSH's considerable heat of hydration, giving thermal storage/cooling for HVAC and solar-thermal energy applications.  More conventional sensible heat storage is also an option. - Leaching:  Acid activity in MSHs is much higher than that in dilute solution.  A hot MSH might therefore act as a "super-leachant" to dissolve refractory minerals.  This has already been shown to be the case in preliminary chloride leaching tests but the mechanism of this effect and the optimum conditions are not clearly understood.