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首页> 外文学位 >Aqueous H(2)SO(4)-Al(2)(SO(4))(3)-MgSO(4) solutions at 250 degrees C: Identification of chemistry and thermodynamics, and application to the pressure acid leaching of laterites.
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Aqueous H(2)SO(4)-Al(2)(SO(4))(3)-MgSO(4) solutions at 250 degrees C: Identification of chemistry and thermodynamics, and application to the pressure acid leaching of laterites.

机译：H（2）SO（4）-Al（2）（SO（4））（3）-MgSO（4）水溶液在250摄氏度下：化学和热力学的鉴定，并应用于红土的加压酸浸。

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A new chemical model for laterite leach solutions (ie., solutions produced in an autoclave during pressure acid leaching of laterites for nickel extraction) is introduced. The major electrolytes in these solutions are H2SO4, Al2(SO4)3, and MgSO4. A hybrid ion-association-interaction approach is implemented to describe the chemistry and thermodynamics of these ternary solutions at 250°C. The complexes in the solution and the ion-interaction parameters (in the Pitzer model) are identified through processing solubility data in the binary, H2SO4-Al2(SO4) 3 and H2SO4-MgSO4, as well as the ternary, H2SO4-Al2(SO4)3-MgSO 4, electrolyte solutions at or near 250°C. The identified aluminum-bearing species are Al3+, Al(SO4)+, and Al 2(SO4)30, with Al2(SO 4)30 as the dominant species at moderate to high H2SO4 concentrations. Also, Mg2+ and MgSO40 are the identified magnesium-bearing species, with Mg2+ being dominant, except at low concentrations of H2SO4. To verify the identified chemistry of H 2SO4-Al2(SO4)3 solutions independently, the electrical conductivities of these solutions at 250°C, measured through a novel conductivity cell and set-up, are analyzed. These measurements show that the conductivity at constant H2SO4 molality drops with increasing Al2(SO4) 3 molality. This behavior is caused through a decrease in H+ molality and an increase in ionic strength. Furthermore, the slope of the conductivity vs. Al2(SO4) 3 molality is much steeper at low Al2(SO4) 3 molalities than at higher values. This is attributed to a much higher dissociation of Al2(SO4)3 at low molalities than at high values. After this confirmation of the solution chemistry, a typical laterite leach solution is simplified to a ternary electrolyte solution that contains H2SO4, Al2(SO4) 3, and pseudo-MgSO4 (i.e., a lumped entity containing all divalent metal sulfates and having the properties of MgSO 4). A chemical model for these solutions at 250°C is developed (based on the ion-association-interaction approach) and then verified against the measured solubility of aluminum in real leach solutions. It is found that a higher concentration of H2SO4 when processing high-Mg ores is required than that when processing low-Mg ores. This is due to the requirement to maintain the same level of true acidity (i.e., H+ molality rather than H2SO4 molality) "at temperature" in order to obtain comparable Ni extraction rates. Finally, based on the true acidity "at temperature", a new general rate equation for nickel extraction is also developed.
机译：介绍了一种用于红土浸出液（即在高压浸出红土的酸浸提镍过程中在高压釜中产生的溶液）的新化学模型。这些溶液中的主要电解质是H2SO4，Al2（SO4）3和MgSO4。采用混合离子缔合相互作用方法描述了这些三元溶液在250°C下的化学和热力学。通过处理二元H2SO4-Al2（SO4）3和H2SO4-MgSO4以及三元H2SO4-Al2（SO4）中的溶解度数据，可以确定溶液中的络合物和离子相互作用参数（在Pitzer模型中） ）3-MgSO 4，在250°C或附近的电解质溶液。鉴定出的含铝物质为Al3 +，Al（SO4）+和Al 2（SO4）30，其中Al2（SO 4）30为中等至高H2SO4浓度下的主要物质。此外，Mg2 +和MgSO40是确定的含镁物质，除了低浓度的H2SO4外，Mg2 +占主导。为了独立验证H 2SO4-Al2（SO4）3溶液的化学性质，分析了这些溶液在250°C时的电导率，该电导率是通过新型电导池和装置测得的。这些测量结果表明，在恒定H2SO4摩尔浓度下，电导率随Al2（SO4）3摩尔浓度的增加而降低。此行为是由于H +摩尔浓度的降低和离子强度的提高引起的。此外，在较低的Al2（SO4）3摩尔浓度下，电导率与Al2（SO4）3摩尔浓度的斜率比在较高值下的斜率要陡得多。这归因于低摩尔浓度下Al2（SO4）3的解离度高于高摩尔浓度下的解离。确认溶液化学性质后，将典型的红土浸出溶液简化为包含H2SO4，Al2（SO4）3和假MgSO4的三元电解质溶液（即，包含所有二价金属硫酸盐的集总实体，其性质为MgSO 4）。建立了这些溶液在250°C下的化学模型（基于离子缔合相互作用方法），然后针对实测浸出溶液中铝的溶解度进行了验证。已发现，与处理低镁矿石相比，处理高镁矿石时需要更高的硫酸浓度。这是由于需要在“温度”下保持相同水平的真实酸度（即，H +摩尔浓度而不是H 2 SO 4摩尔浓度）以获得可比的Ni提取速率。最后，基于“在温度下”的真实酸度，还开发了一个新的镍萃取总速率方程。

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