In nature, metals are not available in pure form. They are found contaminated with other elements in materials called ores. The unwanted material in an ore is called gangue. The process of removing the gangue from the ore to obtain the pure metal is called the concentration of ores. In this article, we look at the four major methods of concentration of ores.
What is an ore?
It is a naturally occurring solid material from which the metal is extracted.
What is gangue?
It is an unwanted material that is part of minerals and is removed during extraction to obtain pure metal.
Concentration of ore:
It is a process of removing gangue from the ore is known as concentration or benefaction. There are numerous methods, and it is based on the properties of the material(ore).
Methods of concentration of ore:
Hydraulic washing:
In this process, the upward-running water stream is used for washing the powdered ore. The gangue particle is washed off leaving heavier ore particles in it. It can be considered as a type of gravity separation.
Use of hydraulic washing:
Used only for ores that have tin or lead because they are heavier than the gangue particles.
Magnetic separation:
If ore particles or gangue are capable of getting attracted in a magnetic field, then magnetic separation can be used.
Ore is kept in a conveyor which is passed through the magnetic roller.
It’s based on the principle of magnetic properties of ore components.
Froth flotation process
It is used to remove gangue from sulfide ores. Suspension is created in water and ore is powdered and this collector and froth stabilizers are added. Collectors in this increase the non-wettability of the metal part of ore, which allows it to form froth. And the froth stabilizers sustain the froth. Oil wets metal and water wets gangue. Paddles constantly stir up the suspension to form froth. And then this froth metal is skimmed off the top and dried to recover the metal.
Leaching
This process is used when the ore is soluble and insolvent. The powdered ore is dissolved in a strong solution of NaOH, this chemical solution dissolves the metal in the ore and is extracted and separated from the gangue by extraction of the chemical solution. From bauxite ore, the extraction of aluminum metal is done using this process.
See Also
Neutralization reaction
Examples of neutralization reaction
Binary compounds
Conductivity of water
Benedict’s test
15 differences between oxidation reaction and reduction reaction
