Magnesium extraction of ferronickel slag processed by alkali fusion and hydrochloric acid leaching

Abstract

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.

Initial extraction of sodium silicate from sidoarjo mud by alkaline fusion and water leaching

“…The data shows the same pattern as this research. The results of the XRD analysis of the Sidoarjo mud are in accordance with several previous researchers [ 27 , 37 ]. The XRD analysis of the alkaline fusion process product is shown in Fig.…”

“…The mixture was fused in a furnace with variations in time, namely 1 h, 1.5 h, 2 h, 2.5 h, and 3 h. The operating conditions of the alkaline fusion process based on previous researchers were burned at a temperature of 700 °C. This alkaline fusion procedure is based on research [ 27 , 30 ].…”

“…This method requires high energy, but has great potential for large-scale applications [ 26 ]. Pyrometallurgy is more useful for use in the pre-treatment of rocks containing some elements such as magnesium and silicate [ 27 ]. Pyrometallurgical applications to obtain sodium silicate have been carried out by several researchers with different raw materials, namely Copper [ 28 ], phosphor lamp waste [ 29 ], coal fly ash [ 30 ], Bengkulu beach sand [ 25 ].…”

Effect of Mixing Methods Prior the Decomposition Process on the Decomposed Ferronickel Slag

“…Furthermore, it has various opportunities to recycle [3]. Previous studies were conducted to utilize ferronickel slag as materials for cement [4] - [7], concrete [8]- [11], polymer [12], mortar [7], [8], magnesium [13] - [15], magnesium metal and ferro alloy [16] as well as for refractory [17]. The ferronickel slag contains SiO2 41 -46%, MgO 30 -41%, Fe2O3 10 -14%, Al2O3 2 -5%, Cr2O3 1,4 -1,9% and other compounds including rare earth elements (REE) in the amount of less than 1% [15], [18].…”

“…Previous studies were conducted to utilize ferronickel slag as materials for cement [4] - [7], concrete [8]- [11], polymer [12], mortar [7], [8], magnesium [13] - [15], magnesium metal and ferro alloy [16] as well as for refractory [17]. The ferronickel slag contains SiO2 41 -46%, MgO 30 -41%, Fe2O3 10 -14%, Al2O3 2 -5%, Cr2O3 1,4 -1,9% and other compounds including rare earth elements (REE) in the amount of less than 1% [15], [18]. It allows ferronickel slag to be used as secondary raw materials for Si, Mg and REE as well through pyrometallurgy, hydrometallurgy, and combination of both processes.…”