Definitions [8]
The process used for extraction of metals in their pure form from their ores is referred to as Metallurgy. Metallurgy deals with the production and purification of metals and manufacture of alloys.
Ores are crushed into a fine powder in big jaw crushers and ball mills. This process is called Pulverisation.
The process of removing gangue, the rocky impurities like SiO2 present in an ore, is called concentration of an ore or ore dressing and the purified ore is called concentrated ore.
If an ore is a carbonate or a hydrated oxide, it is heated in the absence of air to a temperature that is high but insufficient to melt the ore. The process is known as Calcination.
Roasting is a process of heating the concentrated ore to a high temperature in presence of air.
The arrangement of metals in the decreasing order of their reactivity is called the activity or reactivity series of the metals.
When a mixture of aluminium powder and iron oxide is ignited, the latter is reduced to metal. This process is called aluminothermy.
Refining is the process by which crude metal is purified.
Key Points
- Ore dressing removes impurities (gangue) from ore; the result is concentrated ore.
- Gravity separation uses water to separate denser ore from lighter impurities.
- Magnetic separation separates magnetic ores from non-magnetic impurities.
- Froth flotation separates sulphide ores by forming froth with pine oil and air.
- Leaching dissolves the ore using chemicals; flux is added later to form removable slag.
- Refining means purifying a crude metal by removing impurities.
- Distillation is used for metals such as zinc and mercury, which have low boiling points.
- Liquation is used for soft metals such as lead and tin, which have low melting points.
- Electrorefining uses electricity to purify metals like copper and silver.
- Pure metal collects at the cathode; impurities settle as anode mud.
Important Questions [11]
- The process of heating the concentrated ore in a limited supply or absence of air is ______.
- Complete the Following by Selecting the Correct Option from the Choices Given: the Metal Whose Oxide, Which is Amphoteric, is Reduced to Metal by Carbon Reduction ____________
- Name the Compound Added to Pure Alumina to Lower the Fusion Temperature During the Electrolytic Reduction of Alumina.
- Give Appropriate Scientific Reasons For Zinc Oxide Can Be Reduced to Zinc by Using Carbon Monoxide, but Aluminium Oxide Cannot Be Reduced by a Reducing Agent
- An Element L Consists of Molecules. When L is Heated with Iron Metal, It Forms a Compound Fel. What Chemical Term Would You Use to Describe the Change Undergone by L?
- Name the Following: a Metal Oxide that Can Be Reduced by Hydrogen.
- Write a Balanced Chemical Equation for Each of the Following Reactions : (I) Reduction of Copper (Ii) Oxide by Hydrogen
- The following sketch represents the electroplating of an Iron cup with Nickel metal. During electroplating, the iron cup is placed at the cathode. Why?
- Answer the following questions with reference to the electrorefining of copper: Write the reaction taking place at the cathode.
- Answer the following question with reference to the electrorefining of copper: What is the anode made of?
- Answer the following question with reference to the electrorefining of copper: What do you observe at the cathode?
