开采背景下柴达木盆地东台吉乃尔盐湖氯化锂矿床变化特征

柴达木盆地东台吉乃尔盐湖是中国重要的卤水氯化锂（LiCl）矿床,研究开采前后该矿床的变化特征对进一步合理、可持续地利用盐湖卤水中的锂资源具有十分重要的意义。通过已有钻孔数据（开采前）和实测钻孔数据（开采后）的分析,从氯化锂矿床的水化学、矿体的结构和矿区水盐均衡特征方面做了对比研究。结果表明,开采后氯化锂矿床水化学特征变化明显,潜卤水进一步浓缩,演化普遍进入钾混盐（白钠镁矾）析出阶段,矿床氯化锂品位较开采前提升;承压卤水向相对淡化的趋势演化,在五元体系K⁺、Na⁺/Mg²⁺/Cl^-、SO₄^2--H₂O 25 ℃介稳相图中位于软钾镁矾和白钠镁矾过渡区,矿床氯化锂品位较开采前下降。开采后潜卤水矿体的厚度和面积大幅减小,并形成不连续的南北矿层,改变了开采前原有矿体条状连续分布的特征;开采后承压卤水矿体无明显变化。开采后造成矿区水量补给小于卤水开采量,原有的水盐均衡状态发生变化,开采后水量变化（ΔQ）和盐量变化（ΔQ_c）分别为-2.83×10⁸ m³/a和-3.331×10⁷t/a,盐量正均衡,盐类矿物继续析出。研究结果对矿区的合理开发利用和科学保护提供依据。

Variation characteristics of LiCl deposit under condition of mining in East Taijnar Salt Lake,Qaidam Basin

The East Taijnar Salt Lake is an important LiCl deposit in brine of Qaidam Basin,China.To study on the variation characteristics of this ore deposit before and after mining is of great significance for the rational and sustainable utilization of lithium resources in brine.Base on existing borehole data（before mining） and the measured borehole data（after mining）,the hydrochemistry of the LiCl deposit,the structure of the ore body and the water-salt equilibrium characteristics of the mining area were compared and researched.The results indicated that the hydrochemical characteristics of the LiCl deposit changed obviously after mining,the phreatic brine was further concentrated,and the evolution generally attained the stage of potassium mixed salt（blodite） precipitation,and the grade of LiCl of the deposit was higher than that before mining.The evolution of the confined brine was changed to relative desalination,which lain in the transition zone between picromerite and blodite in the K⁺,Na⁺/Mg²⁺/Cl^-,SO₄^2--H₂O phase diagram at 25 ℃,and the LiCl grade of the deposit was lower than that before mining. After mining,the thickness and area of the phreatic brine deposit decreased greatly,and a discontinuous north-south ore bed was formed,which changed the original forms of continuous strip distribution before mining.There was no significant change in the confined brine ore body after mining.The original water-salt balance changed after mining,water quantity change ΔQ and salt quantity change ΔQ_c were -2.83×10⁸ m³/a and -3.331×10⁷ t/a,respectively,indicating that salt quantity was positive equilibrium,and salt minerals were continue to precipitate.The study could provide the basis for rational exploitation and scientific protection of mining area.