Aluminum production from ore to ingot

Main Stages of Aluminum Production

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1. Mining Bauxite

• Bauxite is the primary ore, rich in aluminum oxide (30–70%).

• It is extracted through open-pit mining and crushed into fine particles.

2. Bayer Process – Producing Alumina (Al₂O₃)

• Crushed bauxite is treated with sodium hydroxide (NaOH) under high pressure and temperature.

• Aluminum oxide dissolves, while impurities (iron, silica, titanium) remain as “red mud.”

• The solution yields aluminum hydroxide (Al(OH)₃), which is then calcined (heated to ~1000 °C) to form alumina (Al₂O₃).

3. Hall-Héroult Electrolysis – Reducing Alumina

• Alumina is dissolved in cryolite (Na₃AlF₆), which lowers the melting point.

• Electrolysis occurs in large cells:

  • Cathode (carbon lining): aluminum ions are reduced → molten aluminum collects at the bottom.

  • Anode (carbon blocks): oxygen reacts with carbon → releases CO₂.

• This step is energy-intensive, consuming ~13–15 MWh per ton of aluminum.

4. Molten Aluminum Collection

• Pure aluminum (99.7%) accumulates at the bottom of the electrolytic cell.

• It is periodically siphoned off and transferred to casting facilities.

5. Casting Aluminum Ingots

• Molten aluminum is poured into molds and cooled.

• The result: ingots, the standard form for further processing (rolling, extrusion, alloying).

• Ingots are then used across industries: construction, transportation, aerospace, packaging, and consumer goods.

Key Notes

• Energy demand: Electrolysis is the most costly stage, so smelters are often located near cheap electricity sources.

• Environmental impact: Bayer process generates red mud, a major waste management challenge.

• Recycling advantage: Secondary aluminum requires only ~5% of the energy compared to primary production.