Enhanced lithium leaching from lepidolite in continuous tubular reactor using H2SO4+H2SiF6 as lixiviant

An acidic mixture of sulfuric and fluosilicic acid (H₂SO₄+H₂SiF₆) was employed as lixiviant to enhance leaching of lithium from lepidolite. The H₂SiF₆ was obtained as a byproduct of anhydrous hydrofluoric acid production, aiming to provide HF molecules. It was found that the HF molecules were the main reaction component and played a key role in strengthening the dissolution of lepidolite. Different factors, including mass ratio of ore/H₂SO₄/H₂SiF₆, concentrations of H₂SO₄ and H₂SiF₆, leaching temperatures (40−80 °C) and time (15−75 min), were investigated. Moreover, an efficient tubular reactor was employed to improve this acid leaching system. Under the optimal conditions (ore/H₂SO₄/H₂SiF₆ mass ratio of 1:0.8:1.6, 80 wt.% H₂SO₄, 15 wt.% H₂SiF₆, 80 °C, 15 min), 97.9% of Li, 96.4% of K, 97.6% of Rb, 96.7% of Cs and 81.4% of Al (mass fraction) were leached. Additionally, a two-step thermal process was proposed to remove fluorine of leaching slurry. This acid treatment using an acidic mixture of H₂SO₄ and H₂SiF₆ in a continuous tubular reactor shows potential as an alternative process to extract lithium from lepidolite.     

卢氏锂辉石-锂云母型稀有多金属矿石工艺矿物学研究

深入研究了卢氏锂辉石-锂云母型稀有多金属矿石的工艺矿物学特征,为矿石选冶工艺提供理论基础和科学依据。查明了矿石中锂辉石、锂云母、绿柱石、铌钽铁矿、锑钽矿、细晶石和铯榴石等稀有金属矿物可供回收利用,石英和长石亦可综合回收,有用矿物占矿物量的94.3%。铌钽矿物与锂云母和锂电气石关系密切,铷无独立矿物、载体矿物为长石和锂云母。锂辉石和锂云母粒度较粗,铌钽铁矿和绿柱石粒度细小。铌钽铁矿主要呈粒柱状、绿柱石主要呈柱状和晶簇状集合体分布于粒间隙及微裂隙中。     

Na2SO4-H2SO4混合焙烧中低品位锂云母提锂研究

采用Na2SO4-H2SO4混合焙烧法处理宜春地区中低品位锂云母（Li2O=1.2-1.4%）,研究了酸浓度、焙烧后粒径、硫酸钠添加量等工艺条件对浸出率的影响。采用TG、XRD、SEM、元素成分分析等方法对焙烧过程进行了分析,探讨了Na2SO4对浸出过程的影响。研究结果表明：在800℃-1000℃的温度下,酸浓度70%、矿粒径80目、硫酸钠添加量100g时,浸出率达到90.0%,优于传统H2SO4法的浸出率（73.0%）。本工艺具有优异的固硅、固铝效果,可大幅度缩减传统工艺浸出过程中除硅、除铝工序;焙烧后的硅渣主要成分为SiO2和Al2O3;硫酸钠的加入加剧了锂云母矿原有结构的破坏,可以大幅度提升锂浸出率     

锂云母复合盐焙烧-水浸提取锂铷铯

采用复合盐焙烧-水浸工艺从锂云母中提取锂、铷、铯,研究了焙烧工艺参数及浸出工艺参数对锂、铷、铯浸出率的影响。结果表明,锂云母精矿焙烧时,复合盐焙烧效果优于单一盐添加剂,CaCl₂+Na₂CO₃组合添加剂具有焙烧时氯气排放少、焙烧矿浸出效果好等优点。从锂云母中回收锂、铷、铯,较佳的焙烧-浸出工艺条件为: CaCl₂+Na₂CO₃组合为焙烧添加剂,锂云母精矿∶CaCl₂∶Na₂CO₃(质量比)=1∶0.5∶0.2,锂云母精矿焙烧温度900 ℃、焙烧时间2 h,对焙烧矿进行室温水浸,浸出时间1 h、液固比2∶1,此时锂、铷、铯浸出率分别为86.64%、92.58%、85.37%。含锂浸出液经2次调节pH值净化除钙,升温至95 ℃后加入饱和Na₂CO₃溶液,结晶得到碳酸锂,样品纯度为99.08％,产品纯度及杂质含量达到一级碳酸锂标准。沉锂母液采用溶剂萃取法分离铷、铯,铯萃取率达到99%以上,铷洗脱率达到96%左右。     

采用硫酸熟化—水浸工艺从锂云母中提取锂铷铯

采用硫酸熟化—水浸工艺进行综合提取锂云母中锂、铷、铯的研究,考察了硫酸浓度、酸矿比、熟化温度、熟化时间、浸出温度、液固比等对锂、铷、铯浸取率的影响。结果表明,提取锂、铷、铯的最优工艺条件为:酸矿比1∶1、硫酸浓度70%、120℃熟化8h、液固比4∶1、50℃浸出1h。在此条件下,锂、铷、铯的浸出率分别为91.42%、88.83%、90.09%。     

从锂云母浸出液中分离铷铯试验研究

采用溶剂萃取法对某锂云母浸出液中的铷、铯进行分离试验。考察萃取剂浓度、料液碱度和萃取相比对铷、铯萃取分离效果的影响。萃取分离铯、铷的较优条件为:萃取剂t-BAMBP浓度0.7mol/L、环己烷+磺化煤油为稀释剂、相比O/A=1、料液碱度0.3mol/L、萃取时间10min,铷萃取率为90.0%,铯萃取率为32.0%。负载有机相洗涤条件为:洗涤液氯化钠浓度0.1mol/L、相比O/A=1、洗涤时间10min,铷洗脱率为80.0%,铯洗损率为9.36%,分离效果较好。