【作者】 王旭；

【导师】 刘梅堂； 刘益民；

【作者基本信息】 中国地质大学(北京) ， 工程硕士（专业学位）， 2021， 硕士

【摘要】 新能源的大力发展,对锂电池的需求迅速增加,锂电池行业发展前景广阔。作为新能源发展的关键原料,锂盐的加工工艺主要为硫酸焙烧法,但该工艺会产生大量尾渣,造成资源浪费并污染环境,亟待处理。本文利用水热碱法工艺,以锂辉石提锂尾渣为原料,成功制备纳米高岭石、水化硅酸钙以及硬硅钙石产品,实现该固废资源的高值化利用。该文的主要研究成果有:（1）探究了水洗锂渣-Na OH-H₂O体系分解过程,通过两步水热法分别探究了反应温度、反应时间、Na OH/HNO₃溶液浓度对合成羟钙霞石和纳米高岭石的影响并探讨了反应机理。水洗锂渣在220℃、6mol/kg Na OH溶液中完全分解为方钠石,再转化为羟钙霞石。以羟钙霞石中间产物,在260℃下与0.65mol/kg HNO₃溶液反应24h,成功制备了纳米高岭石。（2）以水洗锂渣脱硅滤液为硅质原料、CaO为钙质原料,通过一步水热法探究了反应温度、反应时间、液固比以及搅拌速度对合成水化硅酸钙粉体的影响。在100℃、液固比为10、反应时间为1h、搅拌速度为300r/min的条件下合成了D90<10μm的水化硅酸钙粉体。（3）以水洗锂渣脱硅滤液为硅质原料、CaO为钙质原料,通过两步水热法探究了反应温度、反应时间、液固比以及陈化时间对合成硬硅钙石的影响并探讨了反应机理。在260℃、液固比为20、反应时间24h、陈化时间12h的条件下成功合成了具有中空二次结构、晶须长径比达到40的硬硅钙石。该文以锂渣为原料合成纳米高岭石副产水化硅酸钙或者硬硅钙石的工艺研究对工业锂辉石提锂尾渣的资源化利用具有重要的实际应用价值。更多还原

【Abstract】 With the vigorous development of new energy,the demand for lithium batteries is increasing rapidly,and the prospects for the lithium battery industry are very broad.As a key raw material for the development of new energy,the processing technology of lithium salt is mainly the sulfuric acid roasting method,but this technology will produce a large amount of tailings,cause waste of resources and pollute the environment,which need to be solved urgently.In this study,with the hydrothermal alkaline process and using the tailings of lithium extraction from spodumene as the raw material,the nano-kaolinite,hydrated calcium silicate and xonotlite products are successfully prepared to realize the high-value utilization of the solid waste resources.The main research results of this article are listed as below.（1）The decomposition process of Washed-lithium slag-Na OH-H₂O system was investigated.The effects of reaction temperature,reaction time and Na OH/HNO₃concentration on the synthesis of hydroxycancrinite and nano-kaolinite were explored by a two-step hydrothermal method,and the reaction mechanism was discussed in detail.The lithium slag was completely decomposed into sodalite in 6 mol/kg Na OH solution at 220℃,and then transformed into hydroxycancrinite.Nano-kaolinite was successfully prepared by the reaction of 0.65 mol/kg HNO₃solution with the intermediate product of hydroxycancrinite at 260℃for 24 h.（2）Using the Washed-lithium slag desilication filtrate as the siliceous raw material and CaO as the calcium raw material,the effects of reaction temperature,reaction time,liquid-solid ratio and stirring speed on the hydrated calcium silicate powder were investigated by a one-step hydrothermal method.Under the conditions of 100℃,liquid-solid ratio of 10,reaction time of 1h,and stirring speed of 300 r/min,a calcium silicate hydrate powder with D90<10μm was synthesized.（3）Using the Washed-lithium slag desilication filtrate as the siliceous raw material and CaO as the calcium raw material,the influence of reaction temperature,reaction time,liquid-solid ratio and aging time on the synthesis of xonotlite was investigated through a two-step hydrothermal method.The reaction mechanism is discussed.The xonotlite with a hollow secondary structure and whisker aspect ratio of 40 was successfully synthesized under the conditions of 260℃,liquid-solid ratio of 20,reaction time of 24 h,and aging time of 12 h.Herein,the synthesis of nano-kaolinite by-product calcium silicate hydrate or xonotlite from lithium slag has important practical value for the resource utilization of industrial spodumene lithium extraction tailings.更多还原