Synthesis of high purity magnesia MgO from Algerian dolomite ore

Abstract

A nanometric Mg(OH)2 and MgO particles with high purity were successfully synthesized from Algerian dolomite via a leaching-precipitation-calcination process. The effect of leaching parameters, such as H2SO4 acid concentration (C), temperature (T), time (t), solid/liquid ratio (S/L), and precipitation parameters: type of precipitating base (KOH, NaOH, NH4OH), OH-/Mg2+ ratio, and temperature on the obtained product properties, were investigated using Taguchi approach. The optimal leaching conditions were selected as: C=5M, T=65°C, t=15 min, and S/L ratio=1:5. Furthermore, the potassium hydroxide (KOH) was selected as the optimal precipitating base with OH-/Mg2+ = 10.5. The calcination of the precipitates at 800°C during 2 h made it possible to produce a high purity MgO (~99.45 %) with a crystallite size of approximately 16.5 nm and particles in the form of agglomerated porous plates with a high SSA (70.42 m2/g) which may be of interest for some applications, such as catalysts or supports.

Keywords

• dolomite
• acid leaching
• precipitation
• mg(oh)2
• mgo
• calcination