Effects of conductive agent type on lithium extraction from salt lake brine with LiFePO_(4) electrodes

Electrochemical lithium extraction from salt lakes is an effective strategy for obtaining lithium at a low cost.Nevertheless,the elevated Mg:Li ratio and the presence of numerous coexisting ions in salt lake brines give rise to challenges,such as prolonged lithium extraction periods,diminished lithium extraction efficiency,and considerable environmental pollution.In this work,Li FePO4(LFP)served as the electrode material for electrochemical lithium extraction.The conductive network in the LFP electrode was optimized by adjusting the type of conductive agent.This approach resulted in high lithium extraction efficiency and extended cycle life.When the single conductive agent of acetylene black(AB)or multiwalled carbon nanotubes(MWCNTs)was replaced with the mixed conductive agent of AB/MWCNTs,the average diffusion coefficient of Li+in the electrode increased from 2.35×10^(-9)or 1.77×10^(-9)to 4.21×10^(-9)cm^(2)·s^(-1).At the current density of 20 mA·g^(-1),the average lithium extraction capacity per gram of LFP electrode increased from 30.36 mg with the single conductive agent(AB)to 35.62 mg with the mixed conductive agent(AB/MWCNTs).When the mixed conductive agent was used,the capacity retention of the electrode after 30 cycles reached 82.9%,which was considerably higher than the capacity retention of 65.8%obtained when the single AB was utilized.Meanwhile,the electrode with mixed conductive agent of AB/MWCNTs provided good cycling performance.When the conductive agent content decreased or the loading capacity increased,the electrode containing the mixed conductive agent continued to show excellent electrochemical performance.Furthermore,a self-designed,highly efficient,continuous lithium extraction device was constructed.The electrode utilizing the AB/MWCNT mixed conductive agent maintained excellent adsorption capacity and cycling performance in this device.This work provides a new perspective for the electrochemical extraction of lithium using LFP electrodes.

Construction of truncated-octahedral LiMn2O4 for battery-like electrochemical lithium recovery from brine

The extraction of lithium from salt lakes or seawater has attracted worldwide attention because of the explosive growth of global demand for lithium products. The LiMn_(2)O_(4)-based electrochemical lithium recovery system is one of the strongest candidates for commercial application due to its high inserted capacity and low energy consumption. However, the surface orientation of LiMn_(2)O_(4)that facilitates Li diffusion happens to be prone to manganese dissolution making it a great challenge to obtain high lithium inserted capacity and long life simultaneously. Herein, we address this problem by designing a truncated octahedral LiMn_(2)O_(4)(Tr-oh LMO) in which the dominant(111) facets minimize Mn dissolution while a small portion of(100) facets facilitate the Li diffusion. Thus, this Tr-oh LMO-based electrochemical lithium recovery system shows excellent Li recovery performance with high inserted capacity(20.25 mg g^(-1)per cycle) in simulated brine. In addition, the dissolution rate of manganese per 30 cycles is only 0.44% and the capacity maintained 85% of the initial after 30 cycles. These promising findings accelerate the practical application of LiMn_(2)O_(4)in electrochemical lithium recovery.

Construction of porous disc-like lithium manganate for rapid and selective electrochemical lithium extraction from brine

In order to satisfy the growing global demand for lithium, selective extraction of lithium from brine has attracted extensive attention. LiMn_(2)O_(4)-based electrochemical lithium recovery system is one of the best choices for commercial applications because of its high selectivity and low energy consumption.However, the low ion diffusion coefficient of lithium manganate limits the further development of electrochemical lithium recovery system. In this work, a novel porous disc-like LiMn_(2)O_(4) was successfully synthesized for the first time via two-step annealing manganese(Ⅱ) precursors. The as-prepared LiMn_(2)O_(4) exhibits porous disc-like morphology, excellent crystallinity, high Li^(+)diffusion coefficient(average 7.6×10^(-9)cm^(2)·s^(-1)), high cycle stability(after 30 uninterrupted extraction and release cycles, the crystal structure hardly changed) and superior rate capacity(93.5% retention from 10-120 mA·g^(-1)). The porous structure and disc-like morphology further promote the contact between lithium ions and electrode materials. Therefore, the assembled electrochemical lithium extraction device with LiMn_(2)O_(4) as positive electrode and silver as negative electrode can realize the rapid and selective extraction of lithium in simulated brine(adsorption capacity of lithium can reach 4.85 mg·g^(-1) in 1 h). The mechanism of disc-like LiMn_(2)O_(4) in electrochemical lithium extraction was proposed based on the analysis of electrochemical characterization and quasi in situ XRD. This novel structure may further promote the practical application of electrochemical lithium extraction from brine.

In Search of Portable Water Supplies within a Brine and Mine Water-Invaded Region for Serving Some Communities around Ishiagu, Afikpo and Environs in Abakaliki Basin, Southeast Nigeria

The study investigates the hydrogeochemical characteristics of some towns in the Abakaliki Basin, comprising, Ishiagu, Aka Eze, Amaseri, Afikpo and Okposi communities, with the aim of sourcing for portable water in the area. The basin is underlain by Albian sediments, essentially shales, in the lowlands, which were affected by low-grade metamorphism that had produced slates. The highlands comprise basic intrusives from episodes of magmatism and metallic ore mineralisation. Injection of brines into the aquifer system and low, seasonal aquifer recharge from rainfall results in poor water quality in the area. The study analyzes the geochemical distribution in water sources in the area and identifies sources of pollutants to guide the better choice of portable water. Results of hydrogeochemical analysis of both surface and groundwater from the communities were compared with World Health Organization to identify portable water locations in the area. While the salt lake at Okposi is the main source of brine intrusion in the study area, the Pb/Zn mine at Ishiagu is the main source of mine-water pollution in the study area. Most chemical parameters, (especially Cl-, Na+, Ca2+, Mg2+, SO42-, HCO3-) maintain high concentrations within the salt lake area, with the values declining away from the salt lake. The main anthropogenic source of pollution in the area, especially at Ishiagu, is the indiscriminate surface mining of lead-zinc without proposer waste management practices. Possible sourcing for portable water in the study area includes a deep borehole at Ishiagu, away from lead-zinc intrusives. At the Okposi axis, searching for portable water in boreholes should target shallower aquifers that do not communicate with the deeper-seated brine zones, likewise targeting zones farther away from these brine-invaded areas. A controlled pumping rate could potentially ensure that the cone of depression was not low enough to reach the brine zone at depth. In addition, desalination could also potentially render the salt water drinkable if properly handled to eliminate the high concentration of salts in the water to the level of acceptable limit by the WHO. Based on the study, the best area to target for portable water in the study area is Afikpo, with most geochemical elements naturally occurring within WHO’s standard concentration while portable water could be harnessed in areas further away from mining sites, especially at deep groundwater.

卤水表面附近盐岩结晶特征研究

【目的】为了弥补现代盐湖沉积考察中丢失的信息,获取盐岩动态结晶过程,指导古盐湖沉积研究。【方法】借助室内石盐蒸发实验,观察卤水蒸发过程中氯化钠结晶特征,分析石盐结晶与沉积环境之间的关系,为盐湖沉积模式建立提供参考。【结果与结论】石盐沉积位置受结晶习性影响,晶体可以在卤水界面之上沉积,其形成的动力除了蒸发泵作用外,还受空气湿度和石盐潮解共同控制;人字晶一般形成于漏斗晶基础之上,在发育空间受限时,绕不同漏斗晶核生长的纹层斜交后形成人字晶纹,两种晶型可以同时沉积于水面之上;盐湖干涸之前,可能经历岩层封锁水面的现象,并可能对临层的碎屑沉积物产生影响。

从高钙富硼老卤中提硼研究

以青海某高钙富硼老卤为研究对象开展了提硼研究。结果表明,合适的萃取条件为:磺化煤油为稀释剂、异辛醇用量50%、萃取相比1.0、萃取混合时间15 min;合适的反萃条件为:反萃剂为pH=1的稀盐酸、反萃相比1.5、反萃混合时间15 min。以此条件在5级混合澄清槽中完成了连续逆流萃取—反萃运转试验,连续运转45 h,硼萃取率为95.49%,硼与钾、钠、钙、镁的分离效果较好;硼反萃率为99.59%,反萃液中硼含量达17.17 g/L。采用“溶剂萃取—反萃—高温蒸发—低温冷却结晶—重溶—冷却结晶—过滤洗涤—干燥”工艺高效分离提取硼,硼总回收率为92.33%,制备出的硼酸产品达国家标准(GB/T 538—2018)要求。

卤水提锂多元新路径:技术、资源、环境和成本

传统沉淀法提锂生产周期长、不适用于低锂浓度卤水,盐湖提锂产量增长缓慢,难以满足新能源产业发展的需求。因此,开发高镁锂比卤水提锂新技术是锂产业发展的迫切需求。本文概述了吸附法、萃取法、膜法和电化学法等提锂新工艺的研究现状,发现铝基吸附剂已应用于工业生产,但其吸附容量显著地小于锰基和钛基吸附剂,而后两者的溶损和长吸附平衡时间是制约其产业化的关键。中性磷类萃取剂关注最多,但其易腐蚀和出现第三相;酰胺类萃取体系无腐蚀,已用于氯化物型卤水工业化提锂,但其稳定性需长期关注;并且萃取法工艺流程较长,酸碱消耗高。膜法无法深度除镁,需与其他方法相结合提锂,其水资源消耗量大。电渗析和“摇椅式”电化学实现了连续性提锂,加速了吸附速率,避免了洗脱剂的使用,其电耗随着优化提锂体系和工作条件的降低,电化学提锂将迎来广阔的产业前景。以上卤水提锂新工艺资源消耗和环境影响小于传统沉淀法,对高镁锂比盐湖具有显著的竞争优势,但各有弊端。因此,未来盐湖卤水提锂应加强多种新技术的集成与耦合,前移提锂过程,提升全流程锂的回收率和多种资源的综合开发。

温度影响下罗布泊盐岩路基填料变形特性研究

为探明温度影响下盐岩路基填料变形特性,保障盐岩路基稳定性,促进盐岩在路基工程中资源化应用,全面分析了卤水及盐岩相变特征,基于正交试验方法探究了单次降温多因素交互作用下盐岩填料的变形规律,系统研究了多次冻融循环后盐岩填料盐胀累积规律,并基于试验段现场监测综合评价了盐湖区盐岩路基变形特征。结果表明:不同浓度卤水降温曲线均未出现明显过冷阶段,其降温曲线平衡及波动维持时间极为短暂,同时卤水相变温度随浓度增加而升高。盐岩填料的降温曲线存在显著的过冷及温度跳跃阶段,其相变温度随拌和卤水浓度增加而下降。单次降温作用下盐岩填料变形量介于-0.09~0.18 mm,各因素对盐岩填料变形的影响顺序为:上覆荷载>含卤水率>最大粒径>压实度。冻融循环作用下拌合卤水浓度越低,盐岩填料盐胀量越大;上覆荷载对盐岩填料盐胀抑制作用较强。实体工程现场监测表明随着监测时间增长盐岩路基变形呈现正弦波式周期性变化,且变形沿深度方向呈减小趋势,同时盐岩路基变形与温度具有较强的线性相关性。

塔里木盆地深层地下卤水全效开发利用新路径

随着油气开采向深层、超深层进发,伴生地下卤水的合理处理成为油气田安全高效绿色开发必须关注的重要的问题,其对油气田的稳定生产、经济效益和区域环境保护都有着重要的影响。为此,以塔里木盆地中国天然气主产区之一的KS气田为例,在分析深层地下卤水处理面临挑战的基础上,提出了“一水分治、深度处理、分治回用”的深层油气田地下卤水电解全效利用新路径,并对其效益进行了系统分析。研究结果表明:①KS气田地下卤水体量大、矿化度较高,具有进一步全效开发利用的价值,气田所处区域太阳能资源丰富但目前尚未被全效利用,基于地下卤水电解全效利用新思路,可实现“废水”“废电”的联合应用;②分离所得的淡水一部分可应用于生态农业、碳汇林业和荒漠化回灌,另一部分可用于回注处理,具有良好的环保效益;③分离所得的淡水和浓缩液,可进一步进行电解水制氢和浓缩液电解获取有价金属,可实现可观的经济效益。结论认为,地下卤水电解全效开发利用在KS气田成功应用后,可推广复制到具有类似条件的其他油气田,为实现资源绿色循环利用、促进降本增效和低碳排放提供了新的思路和办法,有助于油气田的科学效益全面开发。

文化人类学视野下自贡井盐生产工具与技艺——竹笕输卤系统

竹笕输卤系统是自贡盐场传统井盐生产体系中的重要组成部分。文章立足于文化人类学的视野,综合利用晚清民国时期的盐业志书、盐场调查报告、盐务报刊、地方志、历史图片,结合田野调查,探析自贡盐场竹笕输卤产生的背景、竹笕制作安设及其主要装置和笕业,揭示自贡盐场竹笕及其输卤系统的基本面貌,为竹笕输卤技艺的保护、保存和再利用提供基础依据。

锂的圈层循环与资源富集过程:从高原盐湖到造山带伟晶岩

盐湖卤水型锂矿与富锂伟晶岩是目前最为主要的可利用锂资源,前者是经地表风化/高温水岩淋滤形成的水体通过蒸发作用浓缩而成的卤水,而后者被认为是陆表风化沉积物熔融产物经高演化形成的富锂硬岩。大陆地壳是此类表生物质循环最根本的物源,因而探究富锂地壳的形成及其表生风化剥蚀对于理解盐湖与伟晶岩锂成矿至关重要。本文将从元素循环视角切入,结合内生高温-外生低温过程中锂的元素地球化学行为,梳理锂在俯冲带各圈层的循环过程,探讨富锂地壳的形成机制及其对高原盐湖与造山带伟晶岩锂资源发育的影响。研究发现:(1)俯冲板片对弧岩浆锂的物质贡献有限;(2)厚地壳环境下的弧岩浆具有更高的锂含量;(3)造山带富锂弧岩石的循环应是盐湖与伟晶岩锂成矿的重要控制因素。

我国深层地下卤水钾、锂资源及其开发前景

我国已探明的钾、锂资源大多赋存于盐湖卤水矿床中,但经过多年生产地表盐湖资源消耗严重,海相地层寻找钾、锂的工作还未取得突破,深层地下卤水则可成为解决我国锂钾资源需求的后续储备。我国深层地下卤水主要分布在柴西、四川、湖北、江西等地,资源丰富,其中富含高品位的钾、锂、硼等元素,具有很好的经济利用价值,但是目前工作程度还不够,并由于开采技术、成本等问题,还未实现工业开采。文章对我国重点区块深层地下卤水的水化学特征、分布规律等进行了总结,结合已有的深层卤水资源量评价等数据,提出了下一步重点研究的建议区块,可为后续我国深层卤水钾、锂资源评价、综合提取工艺研究等提供科技支撑。

采用沉淀−煅烧法回收盐湖卤水中镁资源制备镁橄榄石耐火材料

通过沉淀−煅烧法研究盐湖锂镁分离和镁资源制备高附加值的镁橄榄石耐火材料。采用Na_(2)SiO_(3)和NaOH组合沉淀剂将盐湖卤水中的锂、镁离子沉淀分离,获得不同MgO/SiO2摩尔比的镁沉淀物。镁沉淀物主要由无定形硅酸镁和氢氧化镁堆积而成,在1400℃条件下的质量残留率均在62%以上。高温烧结实验表明,在Mg/Na_(2)SiO_(3)/NaOH的摩尔比为1:0.6:0.8、烧结温度为1350℃、时间为210 min的条件下,镁沉淀物可制备成性能优良的耐火材料,其耐火度在1800℃以上,抗压强度为190.73 MPa,体积密度为2.53 g/cm^(3),显气孔率为5.94%。所制备的耐火材料主要为镁橄榄石相,含有少量的顽火辉石相。

山东北部泥质海岸带白浪河地区地下水水化学演化过程

莱州湾沿岸是中国海(咸)水入侵典型区域之一,受多次海侵海退事件影响,形成了复杂的地下含水系统。为探究其地下水系统水化学特征及演化规律,对比分析白浪河地区内地下水的水化学特征及主要离子的变化规律,研究了不同分区的水化学演化过程。结果表明,内陆的咸水主要由淡水/卤水混合形成,滨海的咸水主要由淡水/海水混合形成。现存卤水在形成过程中发生了淡水的混入,水岩相互作用和阳离子交换在一定程度上改变了卤水的水化学组成。矿物饱和指数结果表明,不同分区的地下水体中,方解石和白云石基本处于饱和状态,岩盐均未达到饱和状态,石膏仅在卤水中达到饱和状态。从陆到海,地下水系统中发生的阳离子交换过程不同,淡水区和微咸水区浅层的地下水主要是水中的Ca^(2+)与含水介质吸附的Na^(+)交换,而其他分区的阳离子交换过程与之相反。

基于反向传播神经网络的卤水蒸发速率预测模型

卤水的蒸发速率是盐田生产管理中的一个重要技术参数,通过搭建室外卤水蒸发实验装置,分析了辐照强度、风速、环境温度、相对湿度、卤水温度、卤水浓度与卤水蒸发速率的关系。利用反向传播(BP)神经网络,训练构建了卤水蒸发速率预测模型,并与传统的应用回归方法构建的模型进行比较。结果表明,BP神经网络模型和非线性回归模型的决定系数R2分别为0.902和0.884,预测平均相对误差分别为15.723%和18.943%,BP神经网络模型的拟合效果和预测能力均优于非线性回归模型。说明应用BP神经网络构建卤水蒸发速率预测模型是可行的,能够实现蒸发速率的快速估测。

察尔汗盐湖含钾盐储层介质渗流-溶解过程中物性参数变化特征研究

察尔汗盐湖低品位固体钾盐资源丰富,是我国钾盐工业可持续发展的重要后备资源。充分了解储卤层中钾盐矿物的溶解机理有助于提高资源开采的效率。本研究以察尔汗盐湖浅部储卤层中含有不同钾盐矿物的3种典型钻孔岩芯为研究对象,通过室内渗流溶解实验,开展储卤层中固体矿物的溶解效率、孔隙度以及渗透性变化特征模拟研究。室内渗流-溶解实验结果表明,3种储卤层中的钾盐矿物溶出率皆近100%,其中主要含光卤石的岩芯样品溶解速度最快,含钾石盐岩芯次之,含杂卤石岩芯最慢。实验过程中,溶解反应后的储卤层固相骨架皆未塌陷,表明饱和NaCl卤水起到了很好的保护作用。由于石盐析出和不溶矿物的运移堵塞,3种岩芯的孔隙度皆降低,其中含光卤石岩芯孔隙度降低了26%,含钾石盐岩芯孔隙度降低了20%,含杂卤石岩芯孔隙度降低了32%。受控于盐类矿物溶解、石盐的析出和不溶矿物的运移堵塞,各储卤层岩芯渗透性降低幅度为40%~70%,降幅显著。

自贡地下卤水制备富锶功能盐工艺研究

自贡地下卤水蕴含丰富的钠、镁、锂、溴、锶等,可用于生产原盐、镁盐和溴素等工业产品,是碱工业和盐产业重要的液态矿产资源。针对自贡地下卤水富含锶的特点和食盐生产工艺现状,开发了富锶食盐。通过优选草酸作为卤水净化剂,实现卤水除钙镁的同时保留更多的锶,优化的卤水净化工艺:将5.2 mL浓度为0.7 mol/L的草酸以5 mL/min匀速滴加到45℃的100 mL卤水中,调节pH至8.0,搅拌反应30 min后加入0.3 mL质量浓度为2 g/L相对分子质量为800万的聚丙烯酰胺,静置1 h。优化工艺得到的净化卤水经高温蒸发后制得的食盐(以100 g干基计)中锶含量为37.5 mg,是现市售食盐中锶含量的20倍,锶盐其他各项指标均符合GB 2721—2015《食品安全国家标准食用盐》,新工艺实现了自贡卤水锶的综合利用,也为市民提供富锶功能盐的选择。

四川泡菜母水的微生物群落与理化特性分析

为明确泡菜母水中的优势微生物与理化特性的相关性,采用高通量测序技术分析母水中的微生物群落结构,并进行相关性分析。结果表明:泡菜母水的总酸含量为3.00~18.90 g/kg,pH值为3.27~4.71,盐含量为11.00~15.50 g/100 g,检出草酸、苹果酸、琥珀酸和乳酸等7种有机酸。微生物主要群落包括厚壁菌门和子囊菌门2个门,占比均超过99.00%。优势细菌是乳杆菌属、片球菌属,优势真菌是毕赤酵母属、哈克斯坦酵母属、德巴利酵母属。相关性分析表明,乳酸杆菌属与乳酸呈显著正相关关系(P<0.05),与乙酸呈极显著正相关关系(P<0.01)。片球菌属与苹果酸呈极显著正相关关系(P<0.01)。结论:乳酸杆菌和片球菌是泡菜母水的优势微生物,研究结果为泡菜母水高效发酵菌株的选育和泡菜工业化生产提供试验参考。

国内外锂产业发展现状和思考

锂广泛应用于核聚变、动力电池、储能设备中,是新能源和战略新兴产业的关键金属。了解锂资源开发利用现状和趋势,有助于提高国家和企业锂产业竞争力。全球可开发利用的锂矿资源总量丰富但分布不均,新能源行业快速发展带动了锂消费快速上涨和新兴提锂技术进展,地热卤水和油气田卤水等深层卤水、废弃锂电池回收或将成为“新型矿山”。中国是主要锂资源中游加工国,长期以来原料对外依存度较高,随着国外锂资源管控愈发严格,预计未来仍存在较大缺口。通过梳理资源、市场、技术和产业发展趋势,建议加强资源勘查,鼓励油气公司开展“油锂同探”;针对产业链薄弱环节和新兴提锂技术给予政策支持,加强科技攻关,探索中深层卤水提锂和废弃锂电池回收等关键技术;建立回收政策和技术标准体系,保障锂电池回收产业良性发展;加强锂矿开发项目全生命周期分析评价,保障产业可持续发展。

柴达木盆地中深层富钾卤水测井识别模型

柴达木盆地西部中央凹陷区中深层卤水钾含量高,但岩性复杂,孔隙类型多样,为寻找富钾卤水层,进行钾元素测井响应规律研究,利用地层水电阻率谱与体积模型对卤水层钾离子含量进行定量评价。结果表明:基于微电阻率成像数据得到的地层水电阻率谱,通过提取均值和几何均值可有效识别水层,水层的地层水电阻率谱分布窄,谱峰靠前,平均值和几何均值较小;利用钾元素计算体积模型得到储层孔隙度、骨架及泥质含量,结合洗盐前后的电感耦合等离子体发射光谱仪(ICP-OES)可以定量评价卤水层钾离子含量;ICP-OES与自然伽马能谱测井可以对卤水层总钾含量进行标定,结合多元线性回归能够建立卤水层元素评价方法。用体积模型计算的卤水钾含量与试验结果一致性较好。研究结果能够快速、有效的判别卤水钾含量,提高卤水储层的识别能力,为预测研究区卤水空间展布提供重要依据。