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Characterization of brines and evaporite deposits for their lithium contents in the northern part of the Danakil Depression and in some selected areas of the Main Ethiopian Rift lakes
Journal of African Earth Sciences ( IF 2.3 ) Pub Date : 2020-10-01 , DOI: 10.1016/j.jafrearsci.2020.103904
Assnake Bekele , Roland Schmerold

Abstract Lithium is a metal with increasing demand on the global market mainly for its application in lithium ion batteries for electric vehicles. Ethiopia has potential for lithium resources related to pegmatites and to rift-bound brine deposits. The current research focused on known brine lakes and hot springs in the Danakil Depression and the Main Ethiopian Rift. Lithium contents in water samples from rift-bound lakes like Abijata, Shala, Chamo, Abaya, and Chew Bahir show low concentrations consistent with background values for surface waters. Lithium concentrations are elevated in brine lakes, brine ponds, and hot springs of the Danakil Depression. Hot springs in the Dallol contain up to 20 ppm lithium. Lithium enrichment was also noted in residual brines from multi-stage solar evaporation pans during soda-ash production. However, brines produced during precipitation of trona and halite contain about 0.009 ppm lithium, which is well below economically extractable concentrations. Core samples from the Danakil Depression potash exploration reported up to 20–40 ppm in the carnallite and bischofite layers of the evaporite sequence. At least three potential sources for lithium are noted in the Danakil Depression. For example, lithium is leached and mobilized during water rock interactions by deeply circulating and cycling hot meteoric and possibly juvenile geothermal fluids related to the intense volcano-tectonic processes. The current hydrological condition also suggest the possibility of lithium mobilization during surface run off from the basement and Mesozoic sedimentary rocks exposed along the western rift margin of the Danakil Depression. Moreover, variable lithium contents in the different layers of the evaporite sequence suggests, that lithium originated from sea water evaporation before the Danakil Depression became a closed basin. The current research strongly indicates that more detailed investigation is required to evaluate the lithium resources as a primary product and/or as a secondary byproduct during potash mining.

中文翻译:

在达纳基尔凹陷北部和埃塞俄比亚主要裂谷湖的一些选定地区,卤水和蒸发岩沉积物的锂含量特征

摘要 锂是一种在全球市场需求不断增长的金属,主要用于电动汽车锂离子电池。埃塞俄比亚具有与伟晶岩和裂谷盐水矿床相关的锂资源潜力。目前的研究集中在达纳基尔凹陷和埃塞俄比亚主裂谷中已知的盐水湖和温泉。来自裂谷湖(如 Abijata、Shala、Chamo、Abaya 和 Chew Bahir)的水样中的锂含量显示出与地表水背景值一致的低浓度。达纳基尔洼地的盐湖、卤水池和温泉中的锂浓度升高。Dallol 的温泉含有高达 20 ppm 的锂。在纯碱生产过程中,多级太阳能蒸发盘的残留盐水中也发现了锂富集。然而,在天然碱和岩盐沉淀过程中产生的盐水含有约 0.009 ppm 的锂,远低于经济可提取的浓度。Danakil Depression 钾盐勘探的岩心样品报告,蒸发岩层序的光卤石和双闪锌矿层中钾含量高达 20-40 ppm。在达纳基尔洼地中至少发现了三个潜在的锂来源。例如,在水岩相互作用过程中,锂通过深度循环和循环与强烈的火山构造过程相关的热流星体和可能年轻的地热流体而被浸出和移动。当前的水文条件还表明,在沿着达纳基尔凹陷西部裂谷边缘出露的基底和中生代沉积岩的地表径流期间,锂有可能发生迁移。而且,蒸发岩层序不同层中锂含量的变化表明,锂起源于达纳基尔坳陷成为封闭盆地之前的海水蒸发。目前的研究强烈表明,需要进行更详细的调查来评估锂资源作为钾矿开采过程中的初级产品和/或次级副产品。
更新日期:2020-10-01
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