The Production Of Aluminum Ingots Primarily Consists Of Two Stages:Alumina Production (Bayer Process)AndAluminum Electrolysis (Hall-Héroult Process), Followed By Casting To Form Ingots. Below Is A Detailed Breakdown:

I. Alumina Production (Bayer Process)

1. Raw Material Preparation

• Bauxite Ore (Containing Al₂O₃) Is Crushed And Ground Into Fine Powder, Then Mixed With Sodium Hydroxide (NaOH) Solution.

2. High-Pressure Digestion

• The Slurry Is Heated In Autoclaves (140–250°C), Where Alumina Reacts With NaOH To Form Sodium Aluminate Solution:Al2O3+2NaOH→2NaAlO2+H2O

3. Settling & Separation

• The Digested Slurry Undergoes Sedimentation To Remove Insoluble Impurities (E.G., Iron, Silica, Forming "Red Mud").

4. Precipitation & Crystallization

• The Sodium Aluminate Solution Is Cooled, And Aluminum Hydroxide Seed Crystals Are Added To Precipitate Al(OH)₃:NaAlO2+2H2O→Al(OH)3↓+NaOH

5. Calcination

• Aluminum Hydroxide Is Roasted At 1000–1200°C To Produce Alumina (Al₂O₃):2Al(OH)3High Temp.Al2O3+3H2O

II. Aluminum Electrolysis (Hall-Héroult Process)

1. Electrolytic Cell Setup

• Alumina Is Dissolved In Molten Cryolite (Na₃AlF₆) To Form An Electrolyte (~950°C), Lowering The Melting Point.

2. Electrolysis

• Direct Current Is Applied, Triggering The Reaction Between Alumina And Carbon Anodes:2Al2O3+3C→4Al+3CO2↑

• Molten Aluminum Collects At The Cathode, While CO₂ Gas Is Released At The Anode.

3. Tapping

• Liquid Aluminum Is Periodically Siphoned From The Cell Using Vacuum Ladles And Transferred To Holding Furnaces.

III. Ingot Casting

1. Refining

• The Molten Aluminum Undergoes Degassing (E.G., Argon Purging) And Filtration To Remove Impurities. Alloying Elements May Be Added.

2. Casting

• The Refined Aluminum Is Poured Into Molds (E.G., Rectangular Ingot Molds) And Cooled To Solidify.

3. Post-Processing

• Ingots Are Marked (With Batch Numbers, Composition), Stacked, And Stored Or Shipped For Further Processing.

Key Notes

• Energy Consumption: Electrolysis Is Highly Energy-Intensive (~13,500 KWh/Ton Of Al), Accounting For >40% Of Production Costs.

• Environmental Impact: The Process Emits CO₂ And Perfluorocarbons (PFCs). Modern Technologies (E.G., Inert Anodes) Aim To Reduce Emissions.

• Recycling: Smelting Scrap Aluminum Consumes Only ~5% Of The Energy Required For Primary Production, Making It A Sustainable Alternative.