| 摘要: |
| 本文综合利用Na+，K+，Mg2+//Cl-，SO42--H2O五元体系干基图、水图、钠图，研究柴达木盆地一里坪盐湖硫酸盐型卤水水化学特征受外来淡水补给掺杂、选择性溶解、年温差等多因素影响产生的季节性变化，其中温度为主要因素.当卤水温度降低至0℃，开始析出芒硝，水化学变质系数MgSO4/MgCl2比值急剧下降，水化学特征由硫酸镁亚型向氯化物型转化过渡.通过20~25℃晶间卤水L10和L20蒸发实验研究，确定了一里坪卤水蒸发路线、液固相组成、物相鉴定、水化学特征系数、离子行为等变化及成盐特征，并与25℃ Na+，K+，Mg2+//Cl-，SO42--H2O五元体系介稳相图理论预测计算综合对比，二者吻合性比较好，整体相对误差能控制在5%范围内，利用相图理论计算能够很好地指导实际硫酸盐型卤水蒸发析盐.利用水化学特征系数KCl/MgCl2、MgSO4/MgCl2，研究了25℃硫酸盐型盐湖卤水钾盐成盐特征，当变质系数MgSO4/MgCl2高于0.13时，卤水钾盐矿物析出的同时，伴随有泻利盐共同析出.利用含Li+、borate、Mg2+水盐体系相图，研究一里坪老卤水深度蒸发中Li、B的行为，理论预测计算结果，剩余老卤水Mg2+/Li+比值降至27时，卤水中的Li、B始终以离子形式赋存于卤水中继续富集，此时卤水的累积成卤率仅为2.50%~3.20%，须引入新的工艺技术进行Li、B提取.研究结果为极高镁锂比、高镁硼比的硫酸盐型卤水的综合开发利用提供了理论支持. |
| 关键词: 水化学 年温差 变质系数 钾盐成盐 Li、B行为 硫酸盐型卤水 一里坪盐湖 |
| DOI：10.18307/2019.0226 |
| 分类号: |
| 基金项目:国家自然科学基金项目（415030610）、青海盐湖研究所引导基金项目（Y560311147）和青海省重点研发与转化计划项目（2017-GX-145）联合资助. |
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| Hydrochemistry and behavior of K, Li and B in summer evaporation of Yiliping salt lake brine in Qaidam Basin |
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SHI Lijie1,2, WANG Min1,2
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1.Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, P. R. China;2.Key Laboratory of Salt Lake Resources Chemistry of Qinghai Province, Xining 810008, P. R. China
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| Abstract: |
| Combining with the metastable phase diagram of reciprocal quinary system Na+,K+,Mg2+//Cl-,SO42--H2O, the projection phase diagram of water and sodium, this paper studied hydrochemical characteristics of the sulfate-type brine from Yiliping salt lake in Qaidam Basin. They were changed seasonally due to freshwater mixation, selective leaching, and annual temperature difference as the most important factor. While the brine temperature lowered to 0℃, mirabilite crystallized from the brine, the metamorphic coefficient MgSO4/MgCl2 declined sharply, and the hydrochemical characteristic transitioned from magnesium sulfate-type to chloride-type. In this paper, the evaporation experiment of Yiliping brine L10 and L20 had been operated at 20-25℃, and experimental results had been compared with theoretical calculations in the following ways including the evaporation route, chemical compositions of liquid and solid phase, XRD patter analysis, hydrochemical characteristic coefficients, ion behaviors, salt-forming characteristics, and so on. As a result, they were in good agreement with the relative error <5%. Theoretical calculations of the metastable phase diagram Na+,K+, Mg2+//Cl-,SO42--H2O could be used to guide the actual sulfatetype-brine evaporation better. Then, this paper studied the potash-forming characteristic from the magnesium sulfate-type salt lake brine at 25℃ combining with hydrochemical characteristic coefficients KCl/MgCl2 and MgSO4/MgCl2. While the metamorphic coefficient MgSO4/MgCl2 is above 0.13, epsomite has crystallized together with potash. Finally, the behavior of Li and B during further evaporation of brine had been theoretical calculated by using several phase diagrams including Li+, borate, and Mg2+ ions. While the mass ratio of Mg2+/Li+ in the brine was above 27, it was considered that Li and B had accumulated fully in the concentrated brine in the deposition stage of bischofite and epsomite, and the brine accumulated rate declined to 2.50%-3.20%. So it's necessary to extract Li and B from the brine by utilizing new technologies. This results provide theoretical support for the exploitation and comprehensive utilization of the very high Mg2+/Li+ and Mg2+/B2O3 mass ratio sulfatetype-brine. |
| Key words: Hydrochemistry annual temperature difference metamorphic coefficient potash forming behavior of Li and B sulfatetype brine Yiliping salt lake |
