锂辉石浸出液提锂除杂规律研究

Study on law of lithium extraction and impurity removal from spodumene leaching solution

碳酸锂是一种基础锂盐,不仅广泛应用于传统化工行业,也是生产锂电池的重要原料,近年来锂电产业蓬勃发展,极大推动了原料碳酸锂的提取与制备研究。为了提取锂辉石中的锂来制备碳酸锂,利用沉淀溶解-平衡理论分析锂浸出液的除杂规律。对锂辉石进行转型焙烧、酸化焙烧、浸取,锂辉石中98%左右的锂可进入液相,得到锂浸出液,然后根据溶解平衡理论确定3步除杂净化条件:1)中和pH至6.5除大部分Al^(3+)和Fe^(3+);2)加入氧化剂将Fe^(2+)氧化成Fe^(3+),调pH至8.0除Fe^(3+);3)调pH至10.0,加入理论量碳酸钠(以液相Ca^(2+)计),最终Al^(3+)、Fe^(3+)、Mg^(2+)等浓度低于10^(-6)mol/L,Ca^(2+)质量分数约为2×10^(-5)。

As a basic lithium salt,lithium carbonate is not only widely used in the traditional chemical industry,but also an important raw material for the production of lithium batteries.In recent years,the booming development of lithium battery industry has greatly promoted the research on extraction and preparation of raw material of lithium carbonate.In order to extract lithium from spodumene to prepare lithium carbonate,the precipitation dissolution equilibrium theory was used to analyze the impurity removal law of lithium leaching solution.In this study,spodumene from a domestic place was used as raw material to explore the process rules of preparing lithium carbonate.The surface of spodumene was smooth and dense,so it was difficult to react with most acid and alkali(soluble in hydrofluoric acid).Therefore,through the early exploration of reaction temperature and reaction time,α-spodumene could be completely transformed intoβ-spodumene under 1050℃with calcination time of30 minutes.After calcination transformation,the raw material ofβ-spodumene could be mixed with sulfuric acid to calcine to convert lithium into soluble lithium.As a result,about 98%of lithium in spodumene could enter the liquid phase and get the final lithium leaching solution.In order to prepare high-purity lithium carbonate,the process of purification and impurity removal was explored to obtain more accurate pH range of each ion precipitation.The pH range of Al^(3+),Fe^(2+),Fe^(3+),Mg^(2+),Ca^(2+)precipitation was discussed by using the principle of dissolution equilibrium through HSC thermodynamics software and consulting relevant data.Then the three-step decontamination purification condition was determined according to the dissolution equilibrium theory:1)neutralizing the pH to 6.5 to remove Al^(3+)and Fe^(3+);2)adding oxidant to oxidize Fe^(2+)to Fe^(3+)and adjusting the pH to 8.0 to remove Fe^(3+);3)adjusting the pH to 10.0 by adding the theoretical amount of carbonic acid sodium(calculated by Ca^(2+)in the liquid phase),final concentration of Al^(3+),Fe^(3+),Mg^(2+),etc.was lower than 10^(-6) mol/L,and mass content of Ca^(2+)was about 2×10^(-5).