Concentration And Processes of Isolation of Elements

Only a few transition metals occur naturally as free metals. Practically all metallic elements are extracted from their metal oxide or metal sulphide ores. Metallurgy is a collection of procedures for extracting metals from their ores and converting them to more usable forms. 

Metals like sulphur and silicon are stored in the Earth’s crust. Some important metals, such as chloride, can also be present in seawater. They can be found in both a free and a combined state. Gold and platinum, for example, are available in their pure form, whereas other metals are found in a mixed form. Noble metals are metals that exist in their natural condition and have the least amount of chemical reactivity. The metal present in the combined condition, on the other hand, can quickly react. The term “mineral” refers to a naturally occurring material that contains metal. 

Extraction of metals

The extraction of metal from their ores is called mining. Ores are the mixture of metals and some impurities present in the Earth’s crust. The impurity is called gangue. Isolation of metals from ores is necessary to get the desired metal because ores contain metals with other metals and impurities. The process of extraction completes in three steps:

1. The concentration of ore.
2. Extraction of metal from the concentrated ore.
3. Purification of the metal.

Varieties of metals and their ores 

1. Aluminium: Aluminium is used in making wires, utensils, and kitchen items. 

Ores: 

Bauxite- Al₂O₃.₂H₂O

Corundum-Al₂O₃

Felspar- K Al Si₃O₈ Fe₂O₃

Cryolite- Na₃AL F₆ 

Alunite- K₂ SO₄Al₂(SO₄)₃ 4Al (OH)₃

Kryolite- Na₃Al

2.Iron: Iron is an important metal. It is a strong metal and is used in making things such as rods, buildings, vehicles, etc.

Ores: 

Haematite: Fe₂O₃

Magnetite: Fe₃O₄

Siderite: FeCO₃

Iron pyrites: FeS₂ 

3.Zinc: It is an essential mineral that the body needs. It helps in cell growth and heals damages in the body.

Ores: 

Zinc blend: ZnS

Zincite: ZnCO₃

Calamite: ZnO

4.Copper: It is a soft metal used in making utensils, wires, etc., and has high electrical and thermal conductivity.

Ores:

Copper pyrites: CuFeS₂ 

Cuprite: Cu₂ O

Copper glance: Cu₂ S

Malachite: CuCO₃.Cu(OH)₂ 

5.Calcium ores: Dolomite, calcite, gypsum, fluorspar, etc.

6.Silver ores: Ruby Silver and Horn silver.

7.Gold ores: Calaverite and silvenites

Different extraction methods

1. Hydraulic washing: This method is based on gravity separation. The metal and the gangue have specific gravity. To flow over the ground particles, a water jet is used. The impurities are lighter than the ore particles that contain metal. They wash down, while the heavier particles settle in the inclined table’s grooves.
2. Froth flotation method: This method is based on the difference in wetting of the metal and impurities. The ore is finely wetted with water and oil. The ore mixed with water remains in the bottom, and the oil-soaked impurities are eliminated. This method is generally used for sulphide ores. 
3. Magnetic separation: This is an interesting method in which a leather belt (which is magnetic on one side) is rolled. When the ore travels over the belt, the magnetic ore attracts to the magnet. This method is used in extracting rutile, chromite, wolframite, etc.

Leaching or chemical separation: Chemical separation is one method of concentrating the ore. The powdered ore is dissolved with an appropriate chemical reagent, while impurities remain insoluble in the reagent. Bauxite is separated from SiO₂ , Fe₂ O₃, and TiO₂  with the use of NaOH.

Conclusion:

Metallurgy is a branch of science and engineering which investigates the physical and chemical properties of metallic elements. Metallurgy is often known as metal technology or the application of science to metals. Metals are important to us, whether in manufacturing & industrialisation or for usage in vehicles. Metals are extracted from the Earth’s crust by using different extraction methods. Metals are found in a mixed form on Earth. They are then purified and used for many purposes.