Synthesis of Magnesium Aluminate Spinel Powder from the Purified Sodium Hydroxide Leaching Solution of Black Dross

Abstract

Synthesis of magnesium aluminate spinel (MgAl2O4) was investigated by employing ball milling and co-precipitation methods. The starting materials (aluminum hydroxides) were obtained from the purified sodium hydroxide leaching solution of black dross. The characteristics of the synthesized spinel was analyzed through X-ray diffraction (XRD), scanning electron microscopy (SEM) images. In this work, the effect of calcination temperature and time on the formation of spinel by the two methods was compared. Calcination temperature showed a great effect on the formation of spinel in both methods. The results showed that the co-precipitation method has many advantages over the ball milling method. In ball milling method, complete conversion of the starting materials to spinel was impossible even at 1500 °C, while complete conversion to spinel was accomplished at 1000 °C for 5 h by the co-precipitation method. The average size of the spinel synthesized at these optimum conditions of the co-precipitation method was about 17 nm. A process can be developed to synthesize spinel from the black dross which is regarded as hazardous materials.

Synthesis of magnesium aluminate spinel—An overview

“…The precipitates were then filtered off, washed, and dried for 48 h. Spinel phase was observed upon calcination at 600 • C, whereas complete spinellization occurred at 1000 • C/5 h with an average particle size of 17 nm. 96 Recently, a similar work of synthesis of pure MgAl 2 O 4 from waste aluminum dross by the combination of leaching, coprecipitation, and calcination methods was reported by Benkhelif and Kolli. 97 The aluminum dross was chemically leached using H 2 SO 4 solution followed by MgO powder addition (8 wt.%) and precipitation using NH 4 OH solution (pH level was maintained at 9), which upon calcination at 1450 • C led to microstructural transformations yielding almost completely pure spinel (>98%) with an average particle size of 550 nm.…”

“…The coprecipitated spinel precursors were then stirred at 300 rpm at 25°C, and the pH level of the solution was maintained at 8.5 by the controlled addition of NH 4 OH solution. The precipitates were then filtered off, washed, and dried for 48 h. Spinel phase was observed upon calcination at 600°C, whereas complete spinellization occurred at 1000°C/5 h with an average particle size of 17 nm 96 . Recently, a similar work of synthesis of pure MgAl 2 O 4 from waste aluminum dross by the combination of leaching, coprecipitation, and calcination methods was reported by Benkhelif and Kolli 97 .…”

“…95 Synthesis of spinel by coprecipitation method using aluminum hydroxide obtained from purified NaOH leaching solution of black dross was reported by Nguyen and Lee. 96 The aluminum hydroxide powder was dissolved in aqua regia into which MgO powder was added (molar ratio of Al to Mg = 2:1) followed by refluxing for 2 h to prepare a homogenous solution. The coprecipitated spinel precursors were then stirred at 300 rpm at 25 • C, and the pH level of the solution was maintained at 8.5 by the controlled addition of NH 4 OH solution.…”

“…Synthesis of spinel by coprecipitation method using aluminum hydroxide obtained from purified NaOH leaching solution of black dross was reported by Nguyen and Lee 96 . The aluminum hydroxide powder was dissolved in aqua regia into which MgO powder was added (molar ratio of Al to Mg = 2:1) followed by refluxing for 2 h to prepare a homogenous solution.…”

Synthesis of Ferroalloys via Mill Scale-Dross-Graphite Interaction: Implication for Industrial Wastes Upcycling

“…Therefore, a good management method is needed for the tremendous increase in the volume of industrial waste. Aluminum dross had been utilized via several processes and can be classified into wet, dry, and without process [14][15][16][17][18][19][20][21][22][23][24]. The wet process was carried out using acid and base leaching for Al recovery [15], absorbent/catalyst [16,17], and alumina [18,19] productions.…”