Bauxite is not one mineral but a heterogeneous ore containing aluminum hydroxide minerals such as gibbsite, boehmite and diaspore together with iron oxides, silica, clays and titanium minerals. Preparation is defined by the downstream alumina-refining route.
- Correct class
- Heterogeneous aluminum ore
- Main Al minerals
- Gibbsite, boehmite, diaspore
- Critical preparation input
- Reactive silica, clay and moisture behaviour
Why is bauxite not an “aluminum mineral”?
Bauxite is a natural mixture of several aluminum hydroxide minerals and impurities. Mineral proportions, especially silica, iron oxides, clay and titanium minerals, influence refinery behaviour.
Bauxite quality therefore cannot be described by total Al₂O₃ alone.
Crushing, screening and moisture management
Bauxite deposits may contain hard lumps together with fine clay-rich fractions. Crushing and screening are designed not only for size control but also for how fines and clay are managed.
High moisture and stickiness can affect dry screening, bins and transfer; flow behaviour should be observed with representative material.
Boundary with the Bayer process
The common Bayer route for alumina production includes chemical digestion and refining steps. Mechanical preparation sits upstream of that chemistry and focuses on feed size, moisture and homogeneity.
Preparation aims to produce feed at the particle-size, moisture and homogeneity conditions required by the downstream refinery.
Engineering inputs
- Gibbsite/boehmite/diaspore proportion
- Total and reactive silica plus iron oxides
- Clay and fine fraction
- Feed moisture and flow behaviour
- Refinery feed particle-size specification
