iron and steel manufacturing process.ppt

Iron And Steel Manufacturing Process

Four steps:

Iron Making Process

producing iron from iron ore

Methods in iron Making Process

1. Coke-oven-Sinter-BF route 2. Direct Reduction Technique3. Smelting Reduction Technologies

Coke-oven-Sinter-BF route

used by integrated steel plants that produce steel from iron ore.

In this process, the iron ore is first subjected to a sintering process.

Sintering Processis the technology for agglomeration of iron ore fines into useful ‘Blast Furnace’ burden material.

• The treated iron from the sintering plant is fed in to the Blast furnace along with coke. The blast furnace basically does the function of converting iron oxide in to liquid iron. Coke is used as a reducing agent as well as fuel. The output from the furnace is the pure iron in molten stage, which is called hot metal.

•The hot metal output from the Blast furnace is either directly fed in to the Basic Oxygen Furnace or used for producing ‘pig iron’.

Direct Reduction Technique

an alternative to the Blast furnace technique.

This technique produces 97.0 percent pure iron, which is called, solid Sponge Iron.

Smelting Reduction Technologies

In this process, the hot metal (liquid iron) is produced from iron ore in two steps. Ores are partly reduced in the first step and then final reduction and melting, takes place in the second stage.

Corex TechniqueHere coal is directly used in a melter

gesifier as an energy carrier & reducing agent, thereby eliminating the need for a Blast Furnace, Sinter Plant & Coke Ovens

Other techniques used:

- Hismelt- Ausmelt- Romelt- Plasmasmelt- Iron Smelting Reduction (DIOS)

Steel Making Process

producing steel from iron

Types of techniques:

1. Basic Oxygen Furnace (BOF) type

2. Electric arc furnace (EAF) type.

Basic Oxygen Furnace (BOF)

used for producing steel from the refined iron.

Basic Oxygen Furnace (BOF)

• Hot metal from the Blast furnace, which is a pear shaped furnace or reduced iron from the smelting plant is fed in to the Basic Oxygen Furnace (BOF) after pre-treatment to remove undesired elements like sulfur, silicon or phosphorous.

• Molten Steel in liquid form is obtained.• Impurities go out in gaseous form and as slag.

Electric arc furnace (EAF)

Steel scrap is melted using heat generated with the aid of an electric arc produced by graphite electrodes.

In this technique, the output is crude steel which is used in either ingots or fed in the continuous casting process cycle.

Ingot Molten steel cast in vertical cast

iron moulds intended for rolling after heating in two stages i.e. in a primary mill and then in a finishing mill.

Continuous Steel Casting process

liquid steel is directly cast into semi-finished products, which eliminates the need for primary rolling of ingots.

The crude steel or liquid steel is poured into a reciprocating refractory-lined receptacle, called a Tundish.

Below the Tundish are water-cooled copper moulds of desired size.

The steel solidified in the moulds is slowly pulled out to produce an "endless" strand, which is gas-cut to desired lengths.

This steel is called semi-finished steel. The semi-finished steel is fed in to re-rolling mills to get finished steel products.

Finished steel products are classified in to two types:

Finished Carbon Steel- steel that has properties

made up mostly of the element carbon, and which relies on the carbon content for structure.

Classifications:1. Long products2. Flat products3. Other carbon steel product

Long products they are used used in the

construction and engineering industry and, to some extent, in the manufacturing sector.

(e.g. rods, channels, angles and other structural materials)

Flat productsThey may be hot-rolled, cold-rolled or

galvanized and find use mainly in automobile, shipbuilding and the white goods/consumer durables sectors.

Finished Alloy Steel

Alloy steel is defined as a material containing Iron, carbon (less than 2.0 percent), Silicon, Manganese plus Alloy elements like Chromium, Vanadium, Molybdenium, Tungsten, Nickel, Lead, Naboium, Copper etc.

Stainless steel is alloy steel that contains more than 10.0 percent chromium, with or without other alloying elements. Stainless steel has special properties like high level of corrosion resistance and the ability to maintain its strength at high temperatures.