A method of removal of nickel impurity from electrolytic magnesium

The Ni impurity existing in electrolytic Mg cannot be removed using the common settling method since there is a deep eutectic reaction between Ni and Mg. Thermodynamic calculations in this work indicate that the equilibrium solute distribution coefficients of Ni between solid and liquid Mg above the eutectic temperature are far less than 1. The directional solidification method was firstly employed in this work to remove the Ni impurity from the electrolytic Mg. The results show that the Ni impurity in the electrolytic Mg can be almost completely removed (<5 ppm) after the directional solidification process, which meets the requirement of high-purity Mg for Ni content tolerance and is therefore promising for the production of high-purity Mg.