Pig iron is a solid form of hot metal, obtained from iron ore or scrap recycling, and it is processed with a blast furnace or an electric arc furnace. They are used as a raw material for iron steel making and most of this material was imported. Pig iron is also known as crude iron. It is obtained from a smelting furnace in the form of oblong blocks and has a very high carbon content of 3.5 – 4.5 as it contains 90% iron.
Merchant pigs are cold pig iron cast ingots. It’s then sold to third parties as feedstock for steel and ferrous casting industries. Different types of merchant pig iron are basic, foundry, and high-purity pig iron. Well, in this reading, we’ll explore what pig iron is, its applications, properties, composition, types, and how it becomes steel.
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What is a Pig Iron?
Pig iron is a product of smelting iron ore with a high-carbon fuel and reductant like coke and limestone that serve as a flux. Anthracite and charcoal can also be used as fuel and reductant. Pig iron is produced in a blast furnace by smelting iron ore or by smelting ilmenite in an electric furnace.
The majority of pig iron is produced and used within a steel mill, which is one of the major uses of pig iron. Pig iron in this context is known as blast furnace iron, transferred directly to the steel plant in liquid form. This is also known as hot metal, which can be supplied in a variety of ingot sizes and weights, ranging from 3 kg up to more than 50 kg.
Applications
The applications of pig iron in an electric arc furnace are for steelmaking. High-purity pig iron is used in foundries for producing ductile iron castings. Pig iron is also used in foundry pig iron in grey iron castings.
Pig iron is refined into wrought iron through melting and the introduction of hot air. Additionally, pig iron can be converted into gray iron. Historically, pig iron was extracted from the furnace’s bottom and transported to a steel mill for further processing. Currently, the metal is transformed into pellets before shipping.
What are the Properties of pig iron?
Pig iron is also known as crude iron. It is obtained from a smelting furnace in the form of oblong blocks and has a very high carbon content of 3.5 – 4.5 as it contains 90% of iron. It is produced by smelting iron ore with high-carbon fuel and reductants such as coke usually with limestone which serves flux. Other materials like anthracite and charcoal are used as fuel.
The term ‘pig iron’ derives from the old manner of dealing with molten iron. It was run off direct from the furnace into, open channels which feed into numerous short channels on either side, bearing a faint semblance to a sow suckling iron piglets. Pig iron was broken off from the sow when solid. A small amount of cold iron is still known as pig iron today. The term ‘hot metal’ is used to denote molten iron.
Composition of Pig iron
Pig iron contains about 90-95% of elemental iron together with several other elements mainly carbon, silicon, phosphorus, manganese, and sulfur – in varying proportions depending on the compositions of the raw materials and the mode of an operating blast furnace.
Pigs may hold from 3.0 – 4.5% of carbon, 0.5 – 4.0% of silicon, 0.025 – 2.5% phosphorus, 0.15 – 2.15% manganese, and up to 0.2% sulfur. The composition required for steel making differs from that required for use in foundries to make iron castings.
What are the Types of Pig Iron?
Pig Iron consists of three primary types: BASIC PIG IRON, primarily use in electric arc steelmaking; FOUNDRY PIG IRON, predominantly use for the production of grey iron castings through cupola furnaces; and NODULAR PIG IRON (SG GRADE), which is used for the manufacture of ductile iron castings. Pig iron serves various applications, including steel production, foundry work, alloy manufacturing, and automotive and other iron-based castings.
What is Merchant Pig Iron?
Merchant pigs are cold pig iron cast ingots. It’s then sold to third parties as feedstock for steel and ferrous casting industries. It is produced by the dedicated merchant plant (all production is sold to external customers), an integrated steel mill with iron that is surplus to their internal requirements and cast into ingots, and sold to the merchant market.
Types of Merchant Pig Iron
Merchant pigs are basically of three main types:
1. Basic: it is mainly used in electric arc steelmaking
2. Foundry: it is known as hematite pig iron, used mainly in manufacturing grey iron castings in cupola furnaces.
3. High purity: it is known as nodular pig iron, and is used for manufacturing ductile. High-purity pig iron is also called spheroidal graphite – SG iron castings.
How Does Pig Iron Become Steel?
The conversion of pig iron to steel is achieved through the Bessemer process and the basic oxygen furnace. The process involves the extraction of carbon from the iron. Afterward, it produces a metal characterized by its lighter weight, improved flexibility, and rust resistance, known as steel. Steel primarily consists of iron as its key component.