How Aluminium is made from bauxite - Aluminium Factory

Summary

This video explores the aluminum manufacturing process, highlighting the extraction of bauxite, its refinement into alumina, and the subsequent smelting to produce pure aluminum. The process involves multiple steps, including crushing, digesting with caustic soda, and using large pressure tanks to create sodium aluminate. Following precipitation and calcination, the final aluminum is produced through the Hall-Héroult method. Additionally, the video emphasizes the energy efficiency of recycling aluminum, requiring only 5% of the energy needed for new production, and explains the applications of aluminum in industries such as aerospace and electronics.

Takeaways

• 😀 Aluminium is the third most common element on Earth, making up over 8% of the Earth's crust.
• 🏗️ The material is highly versatile and increasingly used in various construction applications.
• ⛏️ Bauxite is the primary raw material for aluminium manufacturing and is often mined from just a few meters below the surface.
• ⚒️ Approximately 4 to 5 tons of bauxite are required to produce 1 ton of aluminium.
• 🧪 The Bayer process is used to extract alumina from bauxite, involving crushing and digesting the bauxite with caustic soda.
• 🌊 The process generates a sodium aluminate solution and leaves behind red mud, which contains unwanted residues.
• ❄️ The sodium aluminate solution is cooled, and aluminium hydroxide seed crystals are added to initiate precipitation.
• 🔥 The resulting aluminium hydroxide crystals are calcined at over 960°C to produce alumina, a white powder.
• ⚡ The Hall-Héroult process is used for smelting alumina into aluminium, requiring high temperatures and electrical currents.
• ♻️ Aluminium recycling uses only 5% of the energy needed to create new aluminium, and recycled aluminium retains its quality.

Q & A

What is the primary raw material used in aluminium production?

The primary raw material used in aluminium production is bauxite.

How much bauxite is required to produce one ton of aluminium?

Approximately 4 to 5 tons of bauxite are required to produce one ton of aluminium.

What is the first step in processing bauxite?

The first step in processing bauxite is crushing and digesting it with a caustic soda solution in large pressure tanks.

What is sodium aluminate, and how is it formed?

Sodium aluminate is a solution formed when bauxite reacts with caustic soda during the crushing and digesting process.

What happens to the red mud during the aluminium production process?

Red mud, which contains iron, silicon, and titanium, sinks to the bottom of the tank and is removed during the settling process.

Describe the precipitation step in aluminium production.

In the precipitation step, aluminium hydroxide seed crystals are added to the sodium aluminate solution to promote the formation of large aluminium hydroxide crystals.

What is calcination, and what does it produce?

Calcination is the process of heating aluminium hydroxide crystals in rotary kilns to over 960°C, resulting in alumina or aluminium oxide.

What is the Hall-Héroult process?

The Hall-Héroult process is the method used to smelt alumina into aluminium by passing electrical currents through a mixture of alumina and molten cryolite.

How pure is the aluminium produced through the smelting process?

The aluminium produced through the smelting process is 99.8% pure.

What are the benefits of recycling aluminium?

Recycling aluminium requires only 5% of the energy needed to produce new aluminium, and it can be recycled indefinitely without losing quality.

How is recycled aluminium processed for reuse?

Recycled aluminium is sorted, cleansed, melted into molten aluminium, and then cast into ingots for rolling, casting, or extruding into new products.

What applications utilize recycled aluminium?

Recycled aluminium is widely used in the aerospace and electronics industries, among others.