Table of content
Introduction
Pig iron is widely used in metallurgy and construction. What is the role of pig iron? How is pig iron related to the common carbon steel and stainless steel? And what is pig iron? How is it made?
This article will explain these questions. I hope it can be helpful to those who don’t know about this product.
What Is Pig Iron?
Pig iron is a crude iron produced by high-temperature smelting. Pig iron contains carbon (3.5%-4.5%), silicon, manganese and sulfur. Pig iron is brittle and cannot be directly used in some products. Therefore, it is often used as some additive raw materials. It can be added to steel, cast iron or wrought iron.
Why Is It Called “Pig Iron”?
The name pig iron is named after the manufacturing method. The production method is to pour molten iron into a mold, which will be divided into several small channels. The main channel is called the runner, and the smaller mold is called the “pig”.
Pig iron is mainly in the form of blocks or ingots.
How Is Pig Iron Made?
Pig iron is made by high-temperature smelting, a process in which coke and limestone are added to the furnace during continuous heating.
Process flow:
1. Iron ore, coke and limestone are added to the top of the smelting furnace.
2. Hot air is injected from the bottom to ignite the coke.
3. As the material descends, the coke reduces the iron ore to molten iron.
4. The limestone reacts with impurities to form slag, which floats to the top of the furnace.
5. The heavier pig iron collects at the bottom and is discharged.
Chemical Composition of Pig Iron
Pig iron typically contains:
92–94% Iron (Fe）
3.5–4.5% Carbon (C)
1–3% Silicon (Si)
0.1–1% Manganese (Mn)
Trace amounts of sulfur and phosphorus
High carbon and other impurities make pig iron brittle, but suitable for further refining.
Types of Pig Iron
Based on the use of pig iron and the content of impurities, pig iron can usually be divided into the following types:
- Basic pig iron: mainly contains low sulfur and low phosphorus, mostly used for steelmaking.
- Casting pig iron: contains a high content of silicon, mostly used to make cast iron.
- High-purity pig iron: has a relatively pure iron content, mostly used for ductile iron or precision casting processing.
- Alloy pig iron: contains elements such as chromium and nickel, mostly used to produce alloy steel.
What Is Pig Iron Used For?
Pig iron cannot usually be used directly in consumer products, but it is mostly used in the industrial industry as an added element to source materials.
Its main uses are:
Steel production: pig iron is added to the raw materials for steel production, and steel is made using a basic oxygen converter or electric arc furnace.
Cast iron manufacturing: composed of some other metal elements, it can be used to produce steel pipes, engine cylinders and other equipment.
Wrought iron: pig iron is made by refining.
Alloy steel raw materials: special pig iron is added with other elements to produce high-grade alloy steel.
Pig Iron vs Cast Iron
Both are high carbon iron, but there are differences.
| Property | Pig Iron | Cast Iron |
|---|---|---|
| Carbon Content | 3.5–4.5% | 2–4% |
| Use | Intermediate material | Final product |
| Form | Ingots or blocks | Molded shapes |
| Brittleness | Very brittle | Less brittle, more durable |
The above table shows the difference between the two. Pig iron is the precursor and cast iron is the finished material.
Pig Iron vs Steel
Steel is formed by reducing the carbon content in pig iron and removing excess impurities.
| Property | Pig Iron | Steel |
|---|---|---|
| Carbon Content | High (3.5–4.5%) | Low (0.1–1.5%) |
| Strength | Brittle | Strong and ductile |
| Processing | Raw material | Refined end product |
Pig iron is usually not used directly, but is used as raw material for further processing.
Global Production and Trade
China, India, Russia and other major steel industry countries are the main sources of steel and are the main producers of pig iron. Global trade has shipped pig iron to all parts of the world. It is just that pig iron is needed wherever there is a need for steel.
Summary
Pig iron is produced through the blast furnace ironmaking process. As a kind of raw material for finishing, it is very important in the industrial steel pipe industry. It can be processed into raw materials such as steel and cast iron to further produce steel pipes, pipe fittings or other industrial supplies.
In short:
Pig iron has a high carbon content.
It is smelted in a blast furnace from iron ore, coke and limestone.
It is mainly used to produce steel and cast iron.
Understanding pig iron is the basis for producing steel and some finished products. Therefore, this article mainly introduces pig iron, hoping to be helpful to beginners.
