Question

extraction of metals

Answer 1

Extraction of Metals

• Highly Reactive Metals

• Moderately Reactive Metals

• Less Reactive Metals

Highly Reactive Metals

1. Metals like Sodium, Potassium, Calcium and Magnesium occurs in Rock Salt ores made up of metal chlorides.

2. Aluminum occurs in it's oxide ore with 2 moles of water [Al2O3 • 2H2O] also called Bauxite.

3. By the process of electrolysis all these metals are seperated from non metals. The metals gather over the cathode (since they are cations) and non metals over anode (since they are anions).

4. For the above process the ores are first concentrated and then brought in molten state.

Moderately Reactive Metals

1. Metals in this group occur in their carbonates and sulphides. Like Zinc Carbonate (Calamine Ore) and Zinc Sulphide (Zinc Blende) are two common compounds from which Zinc is extracted.

2. By process of calcination (heating metal in absence of O2), carbonates are turned into oxides while by process of Roasting (heating metals in pressence of O2), sulphides are turned into oxides.

3. The oxides formed are then reduced by using reducing agents like Carbon (for oxides of Iron, Zinc, Lead & Tin) and Aluminum (for oxides of Manganese and Chromium).

4. During the use of aluminum powder, a large amount of heat is produced that can be used in welding broken pieces.

Less Reactive Metals

1. Such metals (Silver, Copper, Mercury etc.) often exist in their Sulphide Ores. Simply by process for Roasting and Reduction, metals like Mercury are extracted.

2. For Copper

2Cu Sulphide + 3Oxygen → 2Cu Oxide + 2Sulphur Dioxide

2Cu Oxide + Cu Sulphide → 6Cu + Sulphur Dioxide

Hence 6 copper atoms are extracted.

Metals like Gold & Platinum occurs in free state because they are unreactive enough to resist formation of Ores.

Answer 2

Extraction of metals

Metallurgy is the process in which the extraction of the metals are done to obtain the crude metal from their ores is defined as metallurgy.

The three steps involved in the process of metallurgy are:

=> Crushing or grinding of the ore into smaller pieces.

=> Concentration of the or ORE DRESSING or ENRICHMENT OF THE ORE(gangue- to remove the earthly impurities).

=> Converting into oxides by roasting (sulphide ores in presence of O2 and calcination of the carbonate ores in limited amount of O2).

=> Reduction of metal oxides into metals.

=> Refining with the help of ELECTROLYTIC REFINING.

=> Then your PURE METAL is obtained.