粗铌精矿碱介质水热法定向调控选择性提铌应用基础研究

Niobium is an important strategic and scarce resource. The niobium reserves in the iron/rare earth/niobium intergrowth deposit in Inner Mongolia account for 95% of China. But the niobium resources are all dressed into rare earth tailings and cannot be used. In this program, according to the disadvantages of the existing technology, such as low separation selectivity of niobium and impurities, low recovery of niobium, high content of impurities in product and high pollution of waste gas containing fluoride, we proposed a new extraction and separation method with high selectivity of niobium for the crude niobium concentrate using alkaline hydrothermal system based on depth analysis of the physic-chemical properties of it. By study the mineral decomposition law, phase transformation mechanism of hexa-niobate and the mechanism of inhibition stripping of silicon in alkaline medium, the new extraction process with high selectivity of niobium was established through directional phase control of the niobium product; by study the crystallization law of niobium in alkaline solution and the polymerization mechanism of monomeric silicic acid, the new process for the separation of niobium and silicon was established and the recycling of the alkaline medium was realized. On the basis of a comprehensive optimization，a new process was established. Niobium can be selectively extracted with high efficiency through this new process. And Nb2O5 with high purity was achieved through this short and clean process. It is hopeful to solve the sharp contradiction between the demand and the resources of niobium in China and provides theoretical and technical support for the efficient clean extraction and high value utilization of the niobium resource in China.

铌为重要的战略性稀缺资源。内蒙古铁/稀土/铌共生矿床中铌储量占我国总储量95%以上，但铌全部进入稀选尾矿弃置，未能利用。本项目以稀选尾矿浮选得到的粗铌精矿为研究对象，针对现有技术存在的铌与杂质分离选择性差、铌回收率低、产品杂质含量高及含氟废气污染等问题，通过解析粗铌精矿的物相组成与化学反应特性，提出碱介质水热溶出-分离新方法。基于矿物分解规律、铌酸盐物相转化机理与调控机制及强碱介质中硅的抑制溶出机理与机制研究，定向调控铌与硅产物形态，建立铌高效选择性溶出与分离新方法；在此基础上，建立粗铌精矿碱介质水热法高效选择性提铌、短流程清洁制备高纯度Nb2O5新过程。本项目有望解决我国战略铌资源90%依赖进口而国内铌资源无法工业化利用的突出矛盾，为我国大宗特色铌资源高效提取与高值化利用提供理论与技术支撑。

铌为重要的战略性稀缺资源。内蒙古铁/稀土/铌共生矿床中铌储量占我国总储量95%以上，但铌全部进入稀选尾矿弃置，未能利用。本项目以稀选尾矿浮选得到的粗铌精矿为研究对象，针对现有技术存在的铌与杂质分离选择性差、铌回收率低、产品杂质含量高及含氟废气污染等问题，通过解析粗铌精矿的物相组成与化学反应特性，提出了碱介质溶出-分离新方法。研究了粗铌精矿碱介质分解反应热力学，查明了主要物相的分解反应热力学趋势；系统研究了Nb2O5和铌酸盐在不同浓度范围碱介质中的分解和转化规律，通过XRD、拉曼等分析方法查明了铌酸盐溶出及转化过程机理，绘制了正偏盐存在区域相图，建立了铌产物形态的定向调控机制；系统研究了粗铌精矿中各主要组分在碱介质中的溶出行为，查明了温度和碱浓度因素对主要组分溶出的影响规律，确定了铌选择性溶出条件，获得了90%以上的铌溶出率，并考察了强化溶出方法；依据六铌酸盐溶解度变化规律，建立了其与硅及碱介质的结晶分离调控机制，获得了99%以上的结晶率，且实现了与硅及碱介质的高效分离；依据六铌酸盐晶体特性，开发了酸化转型-煅烧技术，实现了六铌酸盐晶体中铌与碱金属离子的分离，制得了含Nb(Ta)2O5 97.4%的初级产品，全流程铌的直收率达89.6%；系统研究了碱介质中硅、铝、锰杂质的脱除方法，通过加入沉淀剂及还原剂，碱介质中SiO2可降至0.5g/L以下，Al可降至1g/L以下，锰可降至10mg/L以下，为碱介质循环利用创造了良好条件；针对提铌后含铌钽渣的物相组成及化学特性，开发了稀酸预处理-氢氟酸转型提铌钽新过程，铌钽浸出率可达99.5%以上，终渣中铌和钽含量可降至0.05%以下。针对铌钽浸出液，开发了低酸萃取分离铌钽新过程，铌和钽的单级萃取率均达90%以上，铌钽分离系数大于500，有效实现了铌钽分离，并最终制得了达到工业级要求的铌、钽产品。本项目有望解决我国战略铌资源90%依赖进口而国内铌资源无法工业化利用的突出矛盾，为我国大宗特色铌资源高效提取与高值化利用提供理论与技术支撑。