摘要
盐湖老卤中镁资源储量丰富,现阶段的初级利用形式主要是提取结晶氯化镁。为提高过程效益,提出了兑卤及变温直接分离高纯结晶硫酸镁的方案,并分别考察MgSO_(4)饱和卤水、MgSO_(4)-NaCl共饱和卤水、MgSO_(4)-NaCl-MgCl_(2)共饱和卤水在非平衡动态降温过程中硫酸镁晶体微观形貌的变化以及降温速率对晶体形貌的影响。结果表明,MgSO_(4)饱和卤水非平衡动态降温过程中晶体形成的速率与降温速率有关,在-1.02℃/min的降温速率下,MgSO_(4)饱和卤水降温30 min后即可形成径向约1300µm的MgSO 4·7H_(2)O晶体;但是,当卤水中存在NaCl时,最终的晶体形式为MgSO_(4)·6H_(2)O,且多为不规则的块状;卤水中的MgCl 2能促使晶体形成棱柱状的MgSO_(4)·6H_(2)O。在NaCl和MgCl_(2)的作用下,MgSO_(4)-NaCl-MgCl_(2)共饱和卤水降温15 h后可以析出完整晶型的高纯结晶硫酸镁。
There are abundant magnesium resources in salt lake brine,and the primary utilization form at present is mainly to extract crystalline magnesium chloride.In order to improve the efficiency of the process,the scheme of directly separating high-purity crystalline magnesium sulfate by adding brine and changing temperature was put forward in this paper,and the changes of magnesium sulfate crystal micro-morphology and the influence of cooling rate on crystal morphology during the non-equilibrium dynamic cooling process of MgSO_(4) saturated brine,MgSO_(4)-NaCl co-saturated brine and MgSO_(4)-NaCl-MgCl_(2) co-saturated brine were investigated.The results show that the rate of crystal formation in the non-equilibrium dynamic cooling process of MgSO 4 saturated brine is related to the cooling rate.At the cooling rate of-1.02℃/min,MgSO_(4) saturated brine can form MgSO_(4)·7H_(2)O crystal with a radial diameter of about 1300µm after cooling for 30 min.However,when NaCl exists in brine,the final crystal form is MgSO_(4)·6H_(2)O,and most of them are irregular blocks.MgCl_(2) in brine can promote the crystal to form prismatic MgSO_(4)·6H_(2)O.Under the action of NaCl and MgCl_(2),MgSO_(4)-NaCl-MgCl_(2) co-saturated brine can precipitate a complete crystal form of high-purity crystalline magnesium sulfate after cooling for 15 h.It is assumed that the initial crystal nucleus determines the crystal form,but the interference of Na^(+)on crystal growth makes the crystals diversified in morphology.
作者
高姣丽
李恩泽
康锦
成怀刚
GAO Jiaoli;LI Enze;KANG Jin;CHENG Huaigang(Institute of Resources and Environmental Engineering,Shanxi University,Taiyuan 030000,Shanxi,China)
出处
《化工学报》
EI
CAS
CSCD
北大核心
2021年第6期3022-3030,共9页
CIESC Journal
基金
国家自然科学基金项目(U20A20149,51674162,51874194,21908137)
山西省“三晋英才”支持计划(2018030140)。
关键词
硫酸镁
盐湖老卤
结晶
分离
显微结构
magnesium sulfate
salt lake tail brine
crystallization
separation
microstructure
