湘南长城岭超大型铷铌钽矿金属元素赋存状态及规律

Occurrence and regularity of ore-forming elements in the Changchengling super-large Rb-Nb-Ta deposit,Southern Hunan

湘南长城岭铷多金属矿床是近年来新发现的超大型铷矿床,伴生有Li,Nb和Ta等稀有金属。采用显微鉴定、岩石地球化学、激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)和矿物自动分析仪(MLA)等测试手段,研究矿区内风吹罗带隐伏岩(矿)体的化学成分、矿物组成、矿物嵌布特征、粒度分布以及铷等稀有金属元素的赋存状态。研究结果表明:矿石主要由石英、绢云母、方解石和白云母组成,质量分数分别为49.49%,33.71%,9.75%和4.78%,约占矿石总质量的97.73%;铷等稀有金属元素主要以类质同象形式赋存于白云母和绢云母中,在白云母中铷、锂和铌+钽质量分数分别为1.030%,0.560%和0.024%;绢云母中铷、锂和铌+钽质量分数分别为0.320%,0.050%和0.022%。白云母多以斑晶形式,嵌布粒度较粗,集中分布在20~40μm粒级间;绢云母呈鳞片状集合体,嵌布粒度主要在<20μm粒级。铷作为主回收元素,在白云母和绢云母中分布率分别为31.32%和68.68%,锂铌钽可作为伴生元素综合回收。通过回收云母类矿物即可有效富集铷等稀有金属,表明了长城岭铷多金属矿床具有高品位、易选冶的特征。

Changchengling deposit in southern Hunan was a newly discovered super-large rubidium deposit,which was associated with Li,Nb,Ta and other rare metals.The chemical compositions,mineral assemblage,mineral dissemination characteristics,particle size range,occurrence of rubidium and other rare metal elements of Fengchuiluodai concealed intrusive rock(ore)were studied by means of multi-test methods,such as microscope identification,chemical analysis,in-situ laser-ablation inductively coupled plasma mass-spectrometry(LA-ICPMS)and mineral liberation analyser(MLA).The results show that the ore minerals mainly consist of quartz,sericite,calcite and muscovite,with the mass fraction of 49.49%,3.71%,9.75%and 4.78%respectively,accounting for 97.73%of the total mass fraction.Rubidium and other rare metal elements host in muscovite and sericite with the form of isomorphism.The mass fraction of rubidium,lithium,niobium and tantalum are 1.030%,0.560%,0.024%in muscovite,respectively.The mass fraction of rubidium,lithium,niobium and tantalum are 0.320%,0.050%,0.022%in sericite,respectively.The muscovite is mostly in the form of phenocryst with coarser grain size,and the grinding fineness of the muscovite is mainly concentrated among 20−40μm.The sericite presents as scaly aggregate,and the grinding fineness of the sericite is mainly distributed<20μm.Rubidium is the main recycling element,which holds distribution ratio of 31.32%and 68.68%in muscovite and sericite respectively.Lithium,niobium and tantalum can be comprehensively recycled as associated elements.Rubidium and other rare metals can be effectively enriched through recovering of mica minerals,indicating that Changchengling rubidium polymetallic deposit has the characteristics of high grade and easy to mineral separation.