(580f) Crystallization Behaviors of Lithium Carbonate in Strong Alkaline Solution: Solubility, Nucleation Mechanism, and Particle Size Control

Crystallization
behaviors of lithium carbonate in strong alkaline solution: solubility,
nucleation mechanism, and particle size control

Youfa Jiang, Chenglin Liu*,
Jin Xue, Mengjie Luo, Ping Li, Jianguo Yu*

State Key laboratory of
Chemical Engineering, National
Engineering Research Center for Integrated Utilization of Salt Lake Resources, East
China University of Science and Technology,

Meilong Road 130, Shanghai, China, 200273.

jiangyoufa2012@126.com, liuchenglin@ecust.edu.cn, jgyu@ecust.edu.cn

Abstract:

Lithium
carbonate is extensively applied in high energy density batteries,¹pharmaceuticals²
and ceramics industry.³
In particular, with the rapid development of lithium-ion battery, the crystallization of lithium
carbonate has drawing increasing attention under various situations, such as
the Li₂CO₃-NaCl-Na₂SO₄-H₂O
system,⁴
reaction between LiCl and CO₂ by use of solvent extraction process,⁵
and the gas-liquid reactive crystallization of CO₂ and LiOH.⁶

In
practice, two natural lithium source are typically utilized for production of
Li₂CO₃: salt brine and lithium-containing minerals,⁷
among which the later accounts for ~70% of total lithium production in China.⁸
The industrial process for extraction of lithium from minerals includes acid
digestion, alkaline digestion and ionic exchange method.⁹
And the soluble lithium in strong alkaline solutions is obtained during
alkaline digestion.¹⁰
The objective of this work is to investigate the reactive crystallization
process of Li₂CO₃ in strong alkaline solution.

In
this study, the solubility of lithium carbonate in alkaline solutions of
different concentrations over the temperature range from 303.15 K to 363.15 K is
firstly investigated. In addition, the Pitzer model is adopted to accurately
estimate the solubility of Li₂CO₃ in NaOH solutions,
which provides a fundamental basis for recovery of lithium from the alkaline
leaching liquor.

The
induction period for lithium carbonate primary nucleation, as a function of
caustic concentration, supersaturation, temperature and string rate, is
subsequently measured by use of focused beam reflectance measurement (FBRM). The
primary nucleation includes homogeneous nucleation and heterogeneous
nucleation, which can be verified according to the correlation between
induction period and supersaturation. The determination of induction period not
only helps obtain important properties such as interfacial tension, and
critical nucleus size, but also contributes to manipulate the crystallization
process to produce products of high quality.

Furthermore,
the operating parameters such as caustic concentration, temperature, the feed rate of Na₂CO₃
solution and the concentration of LiOH are subsequently studied to investigate
the influence on the lithium recovery and the quality of product. And the
mechanism of crystallization of lithium carbonate in strong alkaline solutions
is proposed to highlight the effect of alkali on the morphology and crystal
size distribution (CSD) of lithium carbonate.

Keywords:
lithium carbonate, strong alkaline solution, solubility, nucleation, particle
size control

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