Extraction of Crude Metal From Concentrated Ore

What is Crude Metal?

Metal extraction from a concentrated solution The refining of metals from the compounds in which they are found to their original condition is known as ore. After converting the concentrated ore to oxide, the metal is extracted by reducing the oxide to metal with an appropriate reducing agent. The extraction of metals occurs over three major stages.

1. Concentration of Ore
2. Isolation of metal from concentrated Ore
3. Purification of the metal

Table of Contents

• Recommended videos
• Conversion to Oxide
• Calcination process
• Roasting Process
• Reduction of Oxide to Metal
• Smelting Process
• Alumino Thermite Process
• Frequently Asked Questions

Recommended Videos

Conversion to Oxide

In this process, metal refining is done by heating the ore in a limited supply or absence of air. This is done with the aim of bringing about thermal decomposition and removing volatile compounds from the ore leaving behind a metal oxide.

This is completed in the two processes (i) Calcination Process or (ii) Roasting Process

(1) Calcination Process

Calcination may be defined as the process of heating the ore below its melting point in the absence of air. As a result of calcination, the following changes take place.

Some hydrated ores become anhydrous.

Some carbonate ores are converted into the oxide form.

(2) Roasting Process

Metal extraction here is done by heating the ore with a regular supply of hot air in the furnace. This is done to encourage solid-gas reaction between the ore and the air. Sulphide ores of elements such as Zinc, Lead and Copper are treated using this method.

The sulphur in the ore, at elevated temperature, reacts with the oxygen to create Sulphur Dioxide and escapes out of the ore into the air.

Reduction of Oxide to Metal

The oxide of the metal obtained as a result of Calcination or roasting is converted into a free state by reduction.  Reduction of metal oxide means removal of oxygen to refine the metal to its free state. This is done with the help of reducing agents such as Carbon (C) , Carbon Monoxide (CO),  Hydrogen (H₂), Aluminium (Al).

(1) Smelting Process

In this process, the roasted ore in the form of its oxide is mixed with carbon and heated to a temperature above its melting point in a furnace when the oxide of the metal is reduced to the molten metal.

The carbon under the right condition reacts with metal oxide and takes the oxygen with it thereby reducing the metal and leaving it as carbon monoxide gas. If CO is used as a reducing agent then the gas produced will be carbon dioxide.

(2) Alumino Thermite Process:

Aluminium metal which is highly electropositive can be effectively used for the isolation of metal like chromium, manganese, iron etc. from their ore.

For example: 

Cr₂O₃  + 2Al  → Al₂O₃ + 2Cr

Fe₂O₃  + 2Al → Al₂O₃  + 2Fe 

• A mixture of ferric oxide and aluminium powder is called thermite.
• Aluminothermic reduction is exothermic in nature and liberates a large amount of energy.
• Aluminothermic reduction of Fe₂O₃ also called Thermite Reduction.This is used in the welding of iron. 

We use so many kinds of metals in our daily life and the refining of metals and their eventual extraction and usage affects all of us directly. Metallurgy is a vast treasure-trove of essential knowledge. Come explore it with expert tutors at BYJU’S.