Table 4

Comparison of the Bayer and Pedersen process [40].

Parameter Bayer Process Pedersen Process
Overall process characteristic Hydrometallurgical Pyrometallurgical
Ore type High Al2O3:Fe2O3 ratio Low Al2O3:Fe2O3 ratio
Main byproducts Red mud (not consumable) Pig iron (consumable)
Grey mud (consumable)
Leaching conditions Digestion by NaOH 150–250 °C
High pressure
Digestion by Na2CO3 40–80 °C
Atmospheric pressure
Al(OH)3 precipitation 45–80 °C; 48–70 h 70–80 °C; 6–10 h
Electric energy consumption Reference process 10% higher
Using ores rich in TiO2 and SiO2 Reference process More flexible
Raw materials costs Reference process Higher (∼ 40% in average)
Process costs per unit mass of Alumina Reference process 30–50% lower6

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