铝基锂吸附剂分离高钠型地下卤水锂资源过程研究

铝基锂吸附剂由于其解吸条件温和,不发生溶损,是目前唯一一种成功实现工业化生产的盐湖卤水提锂吸附剂,然而其在高钠型地下卤水中的应用可行性还有待考察。使用实验室自制的H-LDHs颗粒吸附剂,系统研究了吸附液进料流速、解吸温度及解吸液中离子浓度对固定床吸附和解吸过程的影响,实验结果表明,在高钠卤水中,当进料流速从1 BV/h (1 BV/h=0.170 L/h)增加到4 BV/h时,穿透时间缩短了79%,而穿透吸附容量仅降低了17.8%。升高解吸温度可显著提高固定床的Li⁺解吸量,而增大解吸液中的Na⁺浓度会抑制Li⁺的解吸。此外,开发了分段循环解吸工艺,并将其用于四川某地实际地下卤水提锂过程,该工艺能够有效实现解吸工段固定床出料液中Li⁺的富集。     

基于吸附法的模拟盐湖卤水中锂提取分析研究

针对传统硅盐沉淀法无法实现盐湖卤水低浓度锂提取的问题,提出用酸改性高岭土对盐湖卤水中 Li⁺进行提取。试验以锂提取效果为指标对提取工艺进行优化,结果表明,当第一次沉锂工艺条件为：Al/Li摩尔比 3.5,Na/Al 摩尔比 2.7,沉淀温度 45℃,沉淀时间 60min;第二次吸附锂工艺条件为：吸附剂投加量 4g,反应温度 40℃,反应时间 150min,铝锂分离工艺条件为：煅烧时间和温度分别为 50min、400℃,浸取时间和温度分别为 30min 和 50℃,锂沉淀率、锂吸附总量、锂单位吸附量以及 Li⁺浸出率和溶液中 Li⁺质量浓度分别为52.4%、11.7mg、2.9mg·g^{- 1}、95.7%和 1.4g·L^{- 1}。     

铝基锂吸附剂制备及其吸附性能研究

以氯化锂、无水氯化铝为原料,通过正交实验优化反应合成条件,采用“一步法”制备LiCl·2Al（OH）₃·nH₂O型铝基锂吸附剂。分别探究了吸附时间、吸附温度、溶液初始pH、溶液初始Li⁺浓度对吸附性能的影响,对吸附前后的无机铝吸附材料做了表征,并考察了吸附剂的离子选择吸附性及稳定性能。结果表明：最佳吸附条件为在45 ℃下pH=7的锂溶液中吸附2 h,吸附容量高达到8.66 mg/g。XRD、FT-IR表征结果表明：所制吸附材料有良好的稳定性。且该吸附剂对Li⁺分配系数（K=10.06）远高于其他金属阳离子,吸附材料经5次循环使用后,吸附容量仍能保持原来的91.5%。在西藏龙木错盐湖卤水中,对锂的吸附量达到5.24 mg/g。吸附平衡数据拟合结果表明：铝基锂吸附剂符合Langmuir等温吸附模型,吸附是发生在吸附剂表面的单层吸附;吸附过程符合伪二级动力学,是典型的化学吸附过程。     

铝系成型锂吸附剂性能测试评价与对比

我国察尔汗盐湖卤水中蕴含丰富的锂资源,但总体品位较低,具有锂浓度低、镁锂比高的特点,导致开发难度很大。吸附法是针对高镁锂比卤水进行提锂的有效方法,其中铝系锂吸附剂具有洗脱无溶损的优势,目前已在盐湖提锂工业中应用。分别对两种工业化铝系锂吸附剂A、B以及实验室自制吸附剂C进行了系统化表征与吸附性能评价。实验结果显示三种成型吸附剂的有效成分均是锂铝层状氢氧化物,在静态吸附条件下,25℃时吸附剂A、B、C对察尔汗老卤中锂的吸附量分别为2.23、0.45、4.90 mg·g^-1,吸附动力学均符合拟二级动力学方程,不同温度下吸附等温线拟合结果表明Sips三参数模型能够准确描述三种吸附剂的吸附过程。     

锰基吸附剂用于新疆某盐湖卤水提锂工艺

以新疆某高镁锂比盐湖卤水为原料，采用锰基吸附剂进行吸附提锂，考察了不同条件对吸附剂的吸附率、解吸率和锰溶损率的影响，得到最优工艺条件：在吸附时间60 min、吸附液固比50 mL/g条件下，吸附率达到94.34%、吸附容量为7.69 mg/g;在解吸时间15 min、解吸液固比24 mL/g、以0.04 mol/L H₂SO₄溶液为解吸液条件下，解吸率为98.75%,吸附剂锰溶损率为0.019%。     

铝基吸附剂固定床分离卤水锂资源过程研究

铝基锂吸附剂是一种非常适用于低锂品位、高镁锂比盐湖卤水提锂的吸附剂,具有无溶损、稳定性高等优点,也是目前唯一一种已投入工业化生产的吸附剂。使用自制的球形铝基锂吸附剂GLDH填充固定床,系统研究了吸附温度、进料流速、初始锂离子浓度和床层高度对GLDH固定床分离卤水锂资源过程中吸附穿透曲线的影响。结果表明：升高温度、增加床层高度、降低初始锂离子浓度和进料流速会导致穿透时间延长、穿透吸附容量升高。采用BDST、Clark、Thomas、Y-N和M-D-R 5种经验模型对锂吸附穿透曲线进行拟合,确定M-D-R模型能够较准确地描述固定床锂吸附过程。     

盐湖铝系提锂吸附剂成型条件的影响研究

铝系锂吸附剂成型颗粒在盐湖卤水提锂工业应用过程中存在吸附容量低、吸附速率慢和吸附剂粉末脱落等问题。基于现有反溶剂法挤压成型工艺,对盐湖铝系提锂吸附剂成型条件的影响进行了系统性研究。实验结果显示吸附剂成型颗粒粒径越小,达到吸附平衡越快,当颗粒直径d<1 mm时,吸附剂颗粒可在24 h左右达到吸附平衡;降低黏结剂浓度可有效加快吸附剂颗粒的吸附速率,但黏结剂浓度过低会导致其对粉末的包裹性下降;吸附剂颗粒的吸附速率与致孔剂添加比例成正比,当致孔剂添加比例为20%时,吸附剂颗粒能在4 h内完成快速吸附阶段,吸附平衡时对察尔汗高镁锂比盐湖卤水中锂的吸附容量可达4.97 mg·g^-1。     

用于盐湖卤水吸附法提锂的连续离子交换工艺研究

采用连续离子交换技术用于盐湖卤水的吸附法提锂。针对青海一里坪盐湖老卤体系,开发了连续离子交换吸附提锂工艺,研究了操作参数对连续离子交换系统提锂性能的影响,并在优化的工艺条件下进行了长周期的稳定性评价。结果表明,在转动步进周期为20 min、卤水进料量为3.2 BV/h、淋洗水量为2.9 BV/h、解吸水量为9.3 BV/h、解吸温度为15~25 ℃时,连续离子交换系统可以稳定获得镁锂质量浓度比（简称镁锂比）在3左右、锂质量浓度接近1.1 g/L的合格液,锂回收率为98.5%以上。     

离子筛吸附与陶瓷膜耦合用于盐湖卤水提锂

将锰系离子筛吸附与陶瓷膜耦合,用于高镁锂比盐湖卤水的提锂研究。采用水热法制备了高效锂离子筛H_1.6Mn_1.6O₄,考察离子筛用于卤水提锂效果和陶瓷膜的分离性能。结果表明：制备的离子筛粉体粒径分布在100～500 nm之间,平均粒径为160 nm,用于察尔汗盐湖卤水中对Li⁺吸附容量达到31.44 mg·g^-1;孔径50 nm的陶瓷膜对离子筛的截留率达到100%,膜渗透通量大于150 L·m^-2·h^-1;反冲操作可有效维持吸附-膜分离过程的稳定性,吸附与陶瓷膜的耦合过程对盐湖卤水中的锂提取率超过97%,盐酸和双氧水清洗可有效恢复膜渗透通量。研究结果为高镁锂比盐湖卤水提锂提供了新方法。     

高岭土在盐湖卤水提锂中的应用

煅烧酸浸法对高岭土进行处理,得酸改高岭土和铝浸出液。以酸改高岭土对当雄错盐湖卤水中的锂进行吸附,铝浸出液沉淀吸附后卤水中剩余的锂,再以铝浸出液作吸附后酸改高岭土的解吸剂,并对解吸液再次进行沉淀提锂,从而确定高岭土在盐湖卤水提锂中的最佳工艺。结果表明:高岭土煅烧酸浸后Al_2O_3溶出率高,浸出液中的AlCl_3浓度可达0.97mol/L,而所得酸改高岭土孔洞丰富,比表面积较大;以酸改高岭土对锂浓度为320mg/L的卤水进行吸附,发现在酸改高岭土用量为4.0g、体系pH为12、吸附温度为40℃、吸附时间为150min时,有最大锂吸附量,为4.51mg/g;此时,吸附后卤水中锂的浓度为230mg/L,再以铝浸出液沉淀该卤水中的锂,当Al/Li摩尔比为3.5、Na/Al摩尔比为2.7、反应温度为55℃、反应时间为1h时,锂的最大沉淀率为45.3%;将铝浸出液用水稀释1倍,取35m L对4.0g吸附后的酸改高岭土进行解吸,55℃反应20min,Li+解吸率达93.12%,Li+浓度为480mg/L,再次沉淀提锂时,锂沉淀率为84.51%。     

Performance of a synthetic resin for lithium adsorption in waste liquid of extracting aluminum from fly-ash

In this study, we investigated the performance of a synthetic resin for the adsorption of Li from pre-desilicated solution which is the waste liquid produced by extracting aluminum from fly ash. The adsorption kinetics and isotherms of the resin were obtained and analyzed. The saturated adsorption sites of the resin were in agreement with the quasi-second-order kinetic model. Then, the pore diffusion model (PDM) was applied to represent the lithium adsorption kinetics which confirming that the external mass is the limiting step. Moreover, we evaluated the adsorption properties of this resin in fixed-bed mode. We established a feasible extraction process for Li from strong alkaline solutions with low Li concentrations. The process parameters, such as the flow rate, initial adsorption solution concentration, water washing process, desorption agent concentration, and flow rate were studied. The desorption rate of the Li⁺ ions was directly proportional with the concentration of the desorption agent. The time required to accumulate Li decreased as the hydrochloric acid concentration and flow rate increased. Time of the peak appeared increased from 0.5 bed volume (BV) to 2.5 BV as the concentration was increased from 1 to 3 mol·L^-1, and the peak increased from 231 to 394 mg·L^-1. The resin presented good selectivity for Li⁺ ions and could effectively separate impurity ions from the pre-desilication solution.     

纳米片多面体锰基锂离子筛的制备及锂离子吸脱附特性

针对锰基锂离子筛容量发挥不充分、使用寿命短的问题,以电解二氧化锰、氯化锂及无水氯化铝为原料,采用水热法合成了铝原子掺杂锰基离子筛前驱体,经酸洗脱附锂离子后得到锰基锂离子筛H_1.6（Mn_1-x Al _x ）_1.6O₄。扫描电镜结果表明,铝原子掺杂后,样品呈均匀光滑的纳米片多面体形貌,进一步的吸脱附等温线分析显示,样品的比表面积显著提高。锂离子吸脱附特性研究结果表明,Li_1.6（Mn_0.7Al_0.3）_1.6O₄具有最佳的吸附提锂性能,锂离子溶液初始质量浓度为80 mg/L时,吸附容量为32.32 mg/L,5次循环提锂后,锂离子吸附容量可保持为初始吸附容量的95%。这些结果表明,结晶性好、比表面积大的纳米多面体锰基锂离子筛,吸附容量大、结构稳定性好,可为当前盐湖卤水中锂资源的开发和工艺优化提供技术参考。     

锂离子筛研究进展

锂离子筛（锰系、钛系）在高镁锂比（质量比）的盐湖卤水中对锂离子表现出高吸附选择性，尖晶石结构的锂离子筛的提锂机理主要有氧化还原机制、离子交换机制和复合机制，而层状结构的锂离子筛主要通过Li⁺和H⁺之间的简单离子交换实现。锂离子筛的制备工艺简单，首先经过固相燃烧法、微波燃烧法或溶胶-凝胶法、水热法、共沉淀法、熔盐合成法等方法制备出前驱体，再通过H⁺取代相应前驱体中的Li⁺即可。制备的锂离子筛可用于从储量大、品位低的盐湖卤水、海水等液态锂资源中提取锂。近年来研究热点集中于结构稳定性更高的钛锂离子筛，但要进一步提高结构稳定性、实现工程化应用，还需继续研究。     

Preparation and evaluation of α-Al2O3 supported lithium ion sieve membranes for Li+ extraction

Spinel lithium manganese oxide ion-sieves have been considered the most promising adsorbents to extract Li⁺ from brines and sea water. Here, we report a lithium ion-sieve which was successfully loaded onto tubular α-Al₂O₃ ceramic substrates by dipping crystallization and post-calcination method. The lithium manganese oxide Li₄Mn₅O₁₂ was first synthesized onto tubular α-Al₂O₃ ceramic substrates as the ion-sieve precursor (i.e. L-AA), and the corresponding lithium ion-sieve (i.e. H-AA) was obtained after acid pickling. The chemical and morphological properties of the ion-sieve were confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Both L-AA and H-AA showed characteristic peaks of α-Al₂O₃ and cubic phase Li₄Mn₅O₁₂, and the peaks representing cubic phase could still exist after pickling. The lithium manganese oxide Li₄Mn₅O₁₂ could be uniformly loaded not only on the surface of α-Al₂O₃ substrates but also inside the pores. Moreover, we found that the equilibrium adsorption capacity of H-AA was 22.9 mg·g^-1. After 12 h adsorption, the adsorption balance was reached. After 5 cycles of adsorption, the adsorption capacity of H-AA was 60.88% of the initial adsorption capacity. The process of H-AA adsorption for Li⁺ correlated with pseudo-second order kinetic model and Langmuir model. Adsorption thermodynamic parameters regarding enthalpy (ΔH), Gibbs free energy (ΔG) and entropy (ΔS) were calculated. For the dynamic adsorption- desorption process of H-AA, the H-AA exhibited excellent adsorption performance to Li⁺ with the Li⁺ dynamic adsorption capacity of 9.74 mg·g^-1 and the Mn²⁺ dissolution loss rate of 0.99%. After 3 dynamic adsorption-desorption cycles, 80% of the initial dynamic adsorption capacity was still kept.     

Recovery of lithium using H4Mn3.5Ti1.5O12/reduced graphene oxide/polyacrylamide composite hydrogel from brine by Ads-ESIX process

Powdery Li⁺-imprinted manganese oxides adsorbent was widely used to the recovery of Li⁺, but there are some difficulties, such as poor stability in acid solution, inconvenience of operation and separation. In this work, a useful hydrogel composite based H₄Mn_3.5Ti_1.5O₁₂/reduced graphene oxide/polyacrylamide (HMTO-rGO/PAM) was fabricated by thermal initiation method with promising stable, conductive and selective properties. The resulting materials were characterized by field emission scanning electron microscope, infrared absorption spectrum, X-ray diffraction, X-ray photoelectron spectroscopy and electrochemical techniques. The recovery of Li⁺ was investigated using HMTO-rGO/PAM from brine by a separated two-stage sorption statically and electrically switched ion exchange desorption process. The adsorption capacity of 51.5 mg·g^-1 could be achieved with an initial Li⁺ concentration of 200 mg·L^-1 in pH 10, at 45 ℃ for 12 h. Li⁺ ions could be quickly desorbed by cyclic voltammetry (CV) in pH 3, 0.1 mol·L^-1 HCl/NH₄Cl accompanying the exchange of Li⁺ and H⁺(NH₄⁺) and the transfer of LMTO-rGO/PAM to HMTO-rGO/PAM.     

Preparation and characterization of lithium λ-MnO2 ion-sieves

Lithium λ-MnO₂ ion-sieves were prepared from spinel LiMn₂O₄ via treatment with nitric acid. The LiMn₂O₄ was synthesized by a solid state reaction between LiOH·H₂O and MnO₂. The effects of the calcination time and temperature on the preparation of the LiMn₂O₄ precursor and the lithium ion-sieve were investigated. In addition, the Li⁺ extraction ratio, the Mn²⁺ dissolving ratio and the adsorption properties of the lithium ion-sieve were all measured. The lithium ion-sieve had a high exchange capacity and was selective for Li⁺. Specifically, at pH= 13, the ion exchange capacity of Li⁺ was 30.9 mg/g in 10 mmol/L LiCl solution and the lithium extraction ratio and manganese dissolving ratio were 95% and 25%, respectively.