低品位氧化锰矿制备纳米二氧化锰的微观调控机制及电性能研究

The manganese ore reserve in china is about 900 billion ton with 95% of the low grade ore, and it can be only used for 10 years. Nano-manganese dioxide is of similar electrochemical property to ruthenium oxide, and the low price make it become the most promising alternative materials . In this study, nano-manganese dioxide can be prepared from low grade manganese ore by the steps of reduction, remove of impurity and oxidation. In addition, the impurity Fe can be doped during the preparation of nano MnO2 because of high leval Fe in low grade oxide manganese ore, which can be reduced its negative effect. The experimental conditions of Fe-doped nano-manganese dioxide were optimized, and Fe influence on crystal change and growth was analysized in detail. The dioxide manganese in ore was reduced by the biomass at relative low temperature with no introduction of new impurity. After the experimental parameters of ore reduction was optimized, synergistic effect was formed between the ions of Mn2+, impurity and oxidation again for the preparation of the different structure nano-manganese dioxide. This research also focuses on the influences of impurity ions on mechanism of nucleation and oriental crystal growth, and reveals the mechanism of the crystal growth and microstructure control. The relation rule between nano-manganese dioxide microstructures and electrochemical performance is given based on characterization of the product and analysis of its electrochemical performance. These achievements provide a new idea for the comprehensive utilization of manganese ore resources, and nano-manganese dioxide product with good electrical performance can be achieved, instead of expensive electrode active material.

我国锰矿储量约9亿吨，95%为贫矿，静态保障程度仅10年。纳米二氧化锰的电化学性能与氧化钌近似，且价格低廉使其成为最有前途的替代材料。本项目将低品位氧化锰矿经还原，除杂，再氧化可控制备纳米二氧化锰；结合氧化锰矿含铁量高的优势，将铁直接引入纳米二氧化锰的制备过程，降低杂质影响同时进行改性。深入探索铁离子引入二氧化锰空间结构的条件及工艺研究，从微观角度分析铁离子对晶型变化及生长机理的影响，制备铁掺杂改性纳米二氧化锰。采用生物质还原锰矿技术，可实现低温还原且不引入新杂质，优化生物质还原锰矿及材料合成工艺参数，使Mn2+、Fe2+及氧化剂之间建立协同效应，可控合成不同结构纳米二氧化锰，重点揭示晶体生长及微观结构调控机制。通过材料表征和性能测试，建立结构和性能之间的关联规律，优化产品结构。本研究成果可为综合利用锰矿资源提供新思路，同时得到电学性能良好的纳米二氧化锰，替代昂贵的电极活性材料。

锰矿是一种非常重要的矿物资源，广泛应用于冶金，陶瓷，医药等行业；二氧化锰作为过渡金属氧化物，由于其突出的结构性能而吸引了研究学者的广泛关注。因此，开发利用我国低品位的锰矿资源制备特殊结构的二氧化锰具有重要的研究意义。本项目将低品位氧化锰矿经还原，除杂，再氧化可控制备纳米二氧化锰；从微观角度分析晶型结构变化及生长机理的影响。.本项目的主要研究成果可归纳为下述几个方面：1）生物质还原低品位锰矿制备一氧化锰的工艺路线优化；采用生物质还原低品位锰矿，锰矿的还原率在95%以上。2）建立了蜂窝状结构纳米二氧化锰的制备工艺；当控制硫酸锰和高锰酸钾的摩尔比为2.5:3，二者的滴加速度为3ml/min，溶液的pH值为5，反应温度为60℃，静置时间为30分钟，得到蜂窝状结构的二氧化锰；3）蜂窝结构纳米二氧化锰的结构分析和表征；4）二氧化锰纳米线的制备工艺路线，优化的反应条件为：硫酸锰和高锰酸钾的摩尔比为3:1.5，控制溶液的pH值为5，反应温度和时间分别为180℃和10小时，搅拌速度为5Hz，得到结构清晰的二氧化锰纳米线；5）通过扫描电镜对二氧化锰纳米线的结构进行了分析及表征；6）通过材料表征和性能测试，建立结构和性能之间的关联规律，优化产品结构。.本项目为我国锰矿资源的综合回收利用提供了新的方法，大大降低了环境污染，同时得到了高附加值的二氧化锰产品。..