Solubility of in situ oxidized NiO in (Li+Na)Co-3 melts under pressurized oxidant gas conditions

The solubilities of lithiated NiO produced by in situ oxidation of Ni porous plaques have been measured in (Li+Na)CO3 melts under pressurized conditions as a function of partial pressure of CO2, O-2, temperature and Li fraction. The high performance liquid chromatography technique was applied to the solubility measurements. It was found that the NiO solubility in (53+47)mol%(Li+Na)CO3 at 923 K was proportional to CO2 partial pressure (0.1 less than or equal to P(CO2)less than or equal to 3.6 atm, P(O-2)=0.9 atm) and independent of O-2 partial pressure(0.1 less than or equal to P(O-2)less than or equal to 3.6 atm, P(CO2)=0.9 atm). This indicates NiO dissolution under pressurized conditions follows the acidic dissolution mechanism at acidic side, P(CO2)greater than or equal to 0.1 atm. The solubility decreased with increasing temperature from 823 to 973 K at the total pressure of 5 atm of air/CO2 mixed gas, and with increasing Li fraction under the total pressure of 5 atm of O-2/CO2 mixed gas at 923 K. These results are explained in terms of increase of basicity based on the acidic dissolution mechanism.