Skip to main content

What is Pig iron? and how its manufacturing?

Image
By
Pig iron is the crude form of iron and is used as a raw material for the production of various other ferrous metals, such as cast iron, wrought iron and steel. The pig iron is obtained by smelting iron ores in a blast furnace.

The iron ores are found in various forms as shown below:
The metallic contents of these iron ores are given in the following table:
The haematite is widely used for the production of pig iron. Since pyrite contains only 30 to 40% iron, therefore it is not used for manufacturing pig iron.
The pig iron is obtained from the iron ores in the following steps:
1. Concentration. It is the process of removing the impurities like clay, sand etc. from the iron ore by washing with water.
2. Calcination or roasting. It is the process of expelling moisture, carbon dioxide, sulphur and arsenic from the iron ore by heating in shallow kilns.
3. Smelting. It is process of reducing the ore with carbon in the presence of a flux. The smelting is carried out in a large tower called blast furnace.
The blast furnace is a chimney like structure made of heavy steel plates lined inside with fire bricks to a thickness of 1.2 to 1.5 metres. It is about 30 metres high with a maximum internal diameter of 9 meters as its widest cross-section. The portion of the furnace above its widest cross-section is called stack. The top most portion of the stack is called throat through which the charge is fed into the furnace. The charge of the blast furnace consists of calcined ore (8 parts), coke (4 parts) and lime stone (1 part). The portion of the furnace, below its widest cross-section is known as bosh or the burning zone (or zone of fusion). The bosh is provided with holes for a number of water jacketed iron blowing pipes known as tuyers. The tuyers are 12 to 15 in number and are connected to bustle pipe surrounding the furnace.

In the lower part of the blast furnace (called zone of fusion), the temperature is 1200° C to 1300° C. In the middle part of the blast furnace (called zone of absorption), the temperature is 800° C to 1000°C. In the upper part of the blast furnace (called zone of reduction), the temperature is 400° C to 700° C.

At the bottom of the blast furnace, the molten iron sinks down while above this floats the fusible stage which protects the molten iron from oxidation. The molten iron thus produced is known as pig iron. The slag from the blast furnace consists of calcium, aluminum and ferrous silicates. It is used as a ballast for rail roads, mixed with tar for road making and in the cement manufacture.

The pig iron from the blast furnace contains 90 to 92% of iron. The various other elements present in pig iron are carbon (1 to 5%), silicon ( 1 to 2%), manganese (1 to 2%), sulphur and phosphorus (1 to 2%).

Note : Carbon plays an important role in iron. It exists in iron in two forms i.e. either in a free form (as graphite) or in a combined form (as cementite and pearlite). The presence of free carbon in iron imparts softness and a coarse crystalline structure to the metal, while the combined carbon makes the metal hard and gives a fine grained crystalline structure.




Labels:

Comments

Post a Comment

Popular posts from this blog

Team Work - Meaning and Tips for better Team Work

By
A single brain is not always capable of making key decisions on its own. To come up with an efficient solution, an individual requires the help and advice of others. A team is established when individuals get together on a common platform with the common goal of completing a task. To guarantee optimum compatibility, team members should ideally come from similar backgrounds and have a single aim. To provide their best, the team members must complement each other and function as a single unit in tight cooperation. "There is no I in Team Work," as the saying goes, and each member must put the needs of his team first. Personal interests must take a second seat. Any team's performance is directly proportionate to the relationship between its members and their combined efforts. What is the definition of teamwork? Teamwork is defined as the sum of each team member's efforts toward the fulfilment of the team's goal. In other words, any team's backbone is its ability t
Post a Comment
Read more

Scientists discover a new theory / The fundamental property of light – 150 years after Maxwell

By
Light plays a vital role in our everyday lives and technologies based on light are all around us. So we might expect that our understanding of light is pretty settled. But scientists have just uncovered a new fundamental property of light that gives new insight into the 150-year-old classical theory of electromagnetism and which could lead to applications manipulating light at the nanoscale. It is unusual for a pure-theory physics paper to make it into the journal Science. So when one does, it’s worth a closer look. In the new study, researchers bring together one of physics' most venerable set of equations – those of James Clerk’s Maxwell’s famous theory of light – with one of the hot topics in modern solid-state physics: the quantum spin Hall effect and topological insulators . To understand what the fuss is about, let’s first consider the behaviour of electrons in the quantum spin Hall effect. Electrons possess an intrinsic spin as if they were tiny spinning-tops,
Post a Comment
Read more

19 Types Of Content Writing Services For Your Business

By
  It’s hard to know which type of content writing service is the best for your business.  There are so many  different types of content writing services  out there that it’s easy to get confused. You end up wondering if you’re choosing the right one for you. In this post, we’ll get rid of this confusion, once and for all. I’m going to list out the different kinds of writing services you could use.  By the end of this article, you’ll know whether you need a copywriter, a content writer, or a social media marketer and how they can help you achieve your business goals. This post is also useful for writers who want to hone their writing skills in a specific area. Let’s dive in and learn what types of content writing services exist and when you should use them. (Bonus – if you want to  hire the top 1%  of writers, go to the bottom to learn how). Types of Content Writing Services As we go through the list of content writing services, you will find that many of them overlap. That’s perfectly
Post a Comment
Read more