Investigations were conducted to purify crude Li

2

CO

3

via direct carbonation with CO

2

at atmospheric pressure and pyrolysis with both water bath heating method and microwave heating method. The reaction kinetics of LiHCO

3

pyrolysis was studied and the effect of different operating conditions including initial concentration of LiHCO

3

solution

pyrolysis temperature and stirring speed on the purity of Li

2

CO

3

was investigated to obtain the optimal operating conditions. Results showed that the effect law is similar in the two pyrolysis processes. The purity of the Li

2

CO

3

increases firstly and then decreases with the increase of the initial concentration of LiHCO

3

solution and the stirring speed

while the purity of Li

2

CO

3

first decreases and then increases with the increase of pyrolysis temperature. The product yield increases with the increase of initial concentration of LiHCO

3

solution and pyrolysis temperature and is essentially unaffected by the stirring speed. Under the optimal operating conditions

the purity of Li

2

CO

3

can reach up to 99.86% and 99.81% in water bath heating and microwave he

ating process

respectively. In addition

the pyrolysis rate of microwave assisted pyrolysis is 6 times that of water bath heating process

indicating that the microwave heating technology can significantly improve pyrolysis efficiency and reduce energy consumption.