A research using ferronickel slag, the by-product of ferronickel production,
as raw material for magnesium extraction has been carried out. It is
essential to upgrade the value of ferronickel slag instead of used directly
for reclamation materials. Moreover, accumulation due to increasing
ferronickel demand as well as environmental contamination due to various
potencially toxic elements contained in the ferronickel slag could be
prevented. The general objective of this study is to utilize the ferronickel
slag for magnesium materials. The specific objective is to determine the
optimum conditions of magnesium extraction in the process of alkali fusion
followed by hydrochloric acid leaching. A novel method for magnesium
extraction from ferronickel slag was carried out through reducing silica
content followed by acid leaching method. Alkali fusion of the mixture of
ferronickel slag and Na2CO3 at 1000 ?C for 60 minutes followed by water
leaching at 100 ?C for 60 minutes with solid to liquid percentage of 20 %
were carried out to separate the silica. The leaching residue resulted from
water leaching was then leached using hydrochloric aid solution to extract
magnesium. The leaching temperature and time as well as the hycrochloric acid
concentration were varied in the acid leaching process. Alkali fusion process
proved can be generated the sodium silicate that can be separated in the
water leaching to the leached solution. Meanwhile, the leaching residue was
leached using hydrochloric acid to extract the magnesium. The highest
magnesium extraction percentage is 82.67% that resulted from an optimum acid
leaching condition with temperature of 80 ?C for 30 minutes using 2M HCl
solution. Based on the kinetics study, the activation energy (Ea) for the
leaching reaction of magnesium at atmospheric pressure between 32?C to 80?C
is 9.44 kJ/mol and affected by diffusion and chemical reactions.
Magnesium extraction of ferronickel slag processed by alkali fusion and hydrochloric acid leaching
