What is the Difference Between Pig Iron and Wrought Iron

The key difference between pig iron and wrought iron is that pig iron is the impure form of iron, whereas wrought iron is the purest form of iron.

Iron is a metal that we can get from Earth through mining. There are impurities in this mined iron, and we can use many analytical techniques to purify the iron. Pig iron and wrought iron are two forms of iron that are categorized based on purity.

CONTENTS

1. Overview and Key Difference
2. What is Pig Iron 
3. What is Wrought Iron
4. Pig Iron vs Wrought Iron in Tabular Form
5. Summary

What is Pig Iron?

Pig iron is a form of iron we can produce by melting iron ore along with charcoal and limestone under very high pressure. After the process of cooling, the resultant product is named pig iron.  This is a form of iron that has a very high carbon content. It is brittle and unstable, and we cannot use it directly in other applications.

However, refining of this iron form through further melting and blending produce wrought iron, cast iron, and steel, which are very useful as construction materials. Pig iron is believed to have been discovered by Chinese smiths in the 11th century. Pig iron in its true form is not useful, but further processing and refining lead to wrought iron and steel, which are together the most widely used materials on Earth.

What is Wrought Iron?

Wrought iron is the purest iron available for commercial purposes. This type of iron consists of 99.5 – 99.9% iron by weight. Typically, wrought iron contains 0.02% carbon, 0.108% sulfur, 0.12% Silicon, 0.02% Phosphorous and 0.07% slag by weight. Slag contains silicates, aluminosilicates, and calcium-alumina-silicates.

The production of wrought iron includes refining and smelting pig iron in the solid-state. As the word “wrought” implies, wrought iron is made by hammering (working) at a low temperature, which implies that slag is removed by working the metal. Furthermore, we can carry out this reduction in a puddling furnace.

Moreover, wrought iron is useful to make steel and cast iron. It is ductile, tough, malleable, and strong under tensile loads. However, it cannot withstand sudden and excessive shocks. The presence of carbon, which accounts for its resistance to corrosion, makes it suitable for outdoor applications like gates, structural applications, railings, etc. A fracture surface of wrought iron reveals a fibrous structure. The crystallization of wrought iron is an aggregation of cubical crystals.

What is the Difference Between Pig Iron and Wrought Iron?

Pig iron and wrought iron are two forms of iron that are categorized based on purity. The key difference between pig iron and wrought iron is that pig iron is the impure form of iron, whereas wrought iron is the purest form of iron. Furthermore, the pig iron is manufactured by melting iron ore along with charcoal and limestone under very high pressure, whereas the wrought iron is manufactured by refining and smelting pig iron in a solid-state.

The following table tabulates the differences between pig iron and wrought iron for side by side comparison.

Summary – Pig Iron vs Wrought Iron

Pig iron and wrought iron are two forms of iron that are categorized based on purity. The key difference between pig iron and wrought iron is that pig iron is the impure form of iron, whereas wrought iron is the purest form of iron.

Reference:

1. “Wrought Iron.” Encyclopædia Britannica, Encyclopædia Britannica, Inc.

Image Courtesy:

1. “Pig iron” By Mfields1 at en.wikipedia (CC BY 3.0) via Commons Wikimedia
2. “Balcon d’un immeuble parisien” By besopha – Flickr: Le balcon (CC BY-SA 2.0) via Commons Wikimedia