How is cast iron different from pig iron ?

Options

A. cast iron is purest form of iron while pig iron is impure
B. cast iron has lower carbon content (3%) as compared to pig iron (4%) and is extremely hard and brittle.
C. pig iron contains many impurities like S, P, Si and Mn while cast iron does not contain any impurity and can be casted into any shape
D. Cast iron is soft and malleable while pig iron heating it with

Explanation

To differentiate between cast iron and pig iron, we can analyze their composition, properties, and uses. Here’s a step-by-step solution:

### Step 1: Definition of Pig Iron
Pig iron is the intermediate product obtained from the smelting of iron ore in a blast furnace. It typically contains about 4% carbon along with various impurities such as sulfur, phosphorus, silicon, and manganese.

**Hint:** Remember that pig iron is the first stage in the iron production process and has a higher carbon content.

### Step 2: Definition of Cast Iron
Cast iron is produced by melting pig iron and adding a small amount of scrap iron and other alloying elements. It generally contains 2-3% carbon, which is lower than that in pig iron.

**Hint:** Cast iron is derived from pig iron and has a slightly lower carbon content.

### Step 3: Carbon Content Comparison
- **Pig Iron:** Contains approximately 4% carbon.
- **Cast Iron:** Contains about 2-3% carbon.

**Hint:** Focus on the carbon content as a key differentiator between the two types of iron.

### Step 4: Physical Properties
- **Pig Iron:** It is relatively brittle and not suitable for casting.
- **Cast Iron:** It is known for its hardness and brittleness, making it suitable for casting into various shapes.

**Hint:** Think about how the carbon content affects the hardness and brittleness of the iron.

### Step 5: Purity and Impurities
- **Pig Iron:** Contains many impurities, which can affect its quality and usability.
- **Cast Iron:** While it also contains impurities, it is often considered more refined than pig iron due to the additional processing it undergoes.

**Hint:** Consider the implications of impurities on the usability of both types of iron.

### Step 6: Applications
- **Pig Iron:** Used primarily as a raw material for making cast iron and steel.
- **Cast Iron:** Used in making cookware, pipes, and machinery due to its excellent casting properties.

**Hint:** Think about the practical uses of each type of iron to understand their differences better.

### Conclusion
In summary, cast iron differs from pig iron primarily in its carbon content, physical properties, and applications. Cast iron has a lower carbon content (2-3%) compared to pig iron (4%), making it harder and more suitable for casting. Both types contain impurities, but cast iron is often considered more refined.