Difference Between Sponge Iron and Pig Iron

The key difference between sponge iron and pig iron is that we can produce sponge iron by direct reduction of iron ore through reducing agents whereas the production of pig iron is by melting iron ore with charcoal and limestone at very high pressures.

Sponge iron and pig iron are different forms of iron that we can produce from iron ores that occurs naturally under the surface of the earth. Both pig iron and sponge iron have various uses because of difference in properties. Though there are similarities, there are also some differences between pig and sponge iron that we will be discussing in this article.

CONTENTS

1. Overview and Key Difference
2. What is Sponge Iron
3. What is Pig Iron
4. Side by Side Comparison – Sponge Iron and Pig Iron in Tabular Form
5. Summary

What is Sponge Iron?

Sponge iron is a form of iron that we can produce directly from iron ore through a reduction process. This is why we can call it also as “direct reduced iron”. There, the ore is exposed to various reducing agents such as natural gas or gas that emits from coal. Furthermore, we can produce sponge iron from many types of furnaces such as blast furnace, charcoal ovens and oxygen furnaces.

Sponge iron has many advantages over other similarly smelted iron forms. Sponge iron is superior to pig iron as it is richer in iron content. Because of this property, it has many uses in electric furnaces. We can mix sponge iron, in its powdered form with many other metals to manufacture a variety of iron-containing products.

For instance, we can produce wrought iron from sponge iron. It is one type of iron that we use to make ornamental items such as grills and patio furniture. Wrought iron furniture is in high demand and lasts for years if we take proper care of it. Latest methods of making sponge iron have done away with the use of reducing gases; thus, there is no need to melt the ore even.

What is Pig Iron?

Pig iron is a form of iron that we can produce by melting iron ore along with charcoal and limestone under very high pressure. After cooling, the resultant product, which we call pig iron is an iron form that has very high carbon content. Thus, it becomes brittle and unstable that we cannot use directly in this form.

However, we can refine this iron form through further melting and blending to produce wrought iron, cast iron and steel that 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 most widely used materials on earth.

What is the Difference Between Sponge Iron and Pig Iron?

Sponge iron is a form of iron that we can produce directly from iron ore through a reduction process whereas pig iron is a form of iron that we can produce by melting iron ore along with charcoal and limestone under very high pressure. Hence, the key difference between sponge iron and pig iron is that we can produce sponge iron by direct reduction of iron ore through reducing agents whereas the production of pig iron is by melting iron ore with charcoal and limestone at very high pressures.

Furthermore, another difference between sponge iron and pig iron is that the sponge iron is porous while pig iron is not porous, and thus, comparatively denser. Apart from that, there is also a difference between sponge iron and pig iron in their production process. That is; the production process of sponge iron is a liquid state process whereas it is a solid state process for pig iron.

Summary – Sponge Iron vs Pig Iron

Both sponge iron and pig iron are two basic forms of iron that we can obtain via processing natural iron ore. The key difference between sponge iron and pig iron is that we can produce sponge iron by direct reduction of iron ore through reducing agents whereas the production of pig iron is by melting iron ore with charcoal and limestone at very high pressures.

Reference:

1. “Sponge Iron.” :: WELSPUN STEEL LIMITED :. Available here
2. “Pig Iron.” Wikipedia, Wikimedia Foundation, 6 Oct. 2018. Available here

Image Courtesy:

1.”Iron bloom”By Morgan Riley – Own work, (CC BY-SA 3.0) via Commons Wikimedia  
2.”Pig iron”By Mfields1 at en.wikipedia, (CC BY 3.0) via Commons Wikimedia