摘要
锂是保障我国新能源产业发展的核心战略资源。我国青藏高原盐湖中蕴含大量的卤水型锂资源,然而柴达木盆地盐湖卤水高Mg/Li的特点增加了提锂成本,限制了盐湖资源的高效开发利用。硅酸盐矿物在地表风化过程中通常不会发生一致性溶解,而是释放出一定元素的同时形成次生矿物。因此,盐湖物源区风化过程中原生矿物向次生矿物转化行为以及Mg和Li在原生矿物和次生矿物的赋存形式对盐湖Mg/Li有着重要的控制作用。在风化过程中,富镁原生矿物遵循以下路径演化:原生矿物→滑石/三八面体蒙皂石/三八面体蛭石+铁(氢)氧化物→二八面体蒙皂石/二八面体蛭石+铁(氢)氧化物→高岭石/埃洛石+铁(氢)氧化物→三水铝石+铁(氢)氧化物。Mg和Li主要赋存在原生矿物的结构晶格内。而在次生矿物中,Mg和Li可以以三种形式存在:(1)结构单元层八面体片内与氧原子或羟基配位;(2)层间以吸附态存在;(3)矿物边缘以吸附态存在。Mg和Li在滑石中主要赋存于结构单元层中,在蒙皂石和蛭石中赋存于结构单元层与层间,在铁(氢)氧化物、高岭石、埃洛石与三水铝石中以吸附态赋存在矿物边缘。原生矿物水解过程中Mg和Li以原生矿物的Mg、Li比例排出。多数情况下,风化产生的滑石/三八面体蒙脱石或蛭石结构继承自原生矿物,其结构层内Mg/Li与原生矿物相似。而无论是在层间还是边缘位置,Mg相较Li均更难被黏土矿物吸附。因此,盐湖流域区硅酸盐岩风化会产生比自身Mg/Li更高的流体,从而对盐湖卤水高Mg/Li的形成在物源上起到重要作用。
Lithium is a strategic metal crucial for securing China’s new energy development.The salt lakes within the Qaidam Basin of China contain abundant brine-type lithium resources.However,the high Mg/Li ratio characteristic of the salt lake brines in the Qaidam Basin significantly increases lithium extraction costs,limiting the efficient exploitation and utilization of these resources.During the weathering of silicate minerals on the Earth’s surface,congruent dissolution does not typically occur;instead,certain elements are leached while secondary minerals are formed.Therefore,the transformation behavior of primary minerals into secondary minerals during weathering in the source areas of salt lakes,as well as the distributions of Mg and Li in primary and secondary minerals,play a critical role in controlling the Mg/Li ratio in salt lakes.During weathering,magnesium-rich primary minerals evolve as followed:Primary minerals→talc/trioctahedral smectite/trioctahedral vermiculite+iron(hydr)oxides→dioctahedral smectite/dioctahedral vermiculite+iron(hydr)oxides→kaolinite/halloysite+iron(hydr)oxides→gibbsite+iron(hydr)oxides.Mg and Li primarily reside within the lattice of primary minerals.In secondary minerals,however,Mg and Li can exist in three forms:1.Six-fold coordination with oxygen atoms or hydroxyl groups within structural layers.2.Adsorbed in the interlayer space.3.Adsorbed at the mineral edges.In talc,Mg and Li mainly occur within the structural layers.In smectite and vermiculite,they are distributed in both structural layers and interlayer spaces.In iron(hydr)oxides,kaolinite,halloysite,and gibbsite,they primarily exist in an adsorbed state at mineral edges.During the hydrolysis of primary minerals,Mg and Li are leached in a ratio similar to Mg/Li ratios of primary minerals.In most cases,the resulting talc/trioctahedral smectite or vermiculite inherits its structure from the primary minerals,maintaining a similar Mg/Li ratio within the structural layers to the primary minerals.However,whether in interlayer or edge positions,Mg is generally less readily adsorbed by clay minerals compared to Li.Consequently,the weathering of silicate rocks in the source areas of salt lakes generates fluids with a higher Mg/Li ratio than the original rocks,playing a significant role in the formation of high-Mg/Li brine in salt lakes at the source level.
作者
黄曦光
李建森
朱欣桐
李翔
包昕玥
李兴东
张永兴
HUANG Xiguang;LI Jiansen;ZHU Xintong;LI Xiang;BAO Xinyue;LI Xingdong;ZHANG Yongxing(Key Laboratory of Green and High-end Utilization of Salt Lake Resources,Qinghai Institute of Salt Lakes,Chinese Academy of Sciences,Xining,810008,China;Qinghai Provincial Key Laboratory of Geology and Environment of Salt Lakes,Xining,810008,China;University of Chinese Academy of Sciences,Beijing,100049,China;Xining Center of Natural Resources Comprehensive Survey,China Geological Survey,Xining,810008,China)
出处
《盐湖研究》
2025年第4期91-100,共10页
Journal of Salt Lake Research
基金
国家重点研发计划青年科学家项目(2023YFC2908600)
青海省“昆仑英才·高端创新创业人才”计划项目(QHKLYC-GDCXCY-2024-574、QHKLYC-GDCXCY-2024-049)
中国地质调查局地质调查项目(DD20220958)。
