IRON AND STEEL PROCESSINGFuentes, Shirley Morre, Henelaine Tanlangit, MerryJay

What is Iron?

Iron is a metal that is very commonly found on the Earth and even in the Sun and other stars. Because it is so common and has many uses, it is the most used and cheapest of all metals.

has a long history of being used in building bridges, ships, and buildings.

What is steel?

Steel is an alloy made by combining iron and other elements, the most common of these being carbon. When carbon is used, its content in the steel is between 0.2% and 2.1% by weight, depending on the grade. harder than iron and does not rust as easily

Raw materials in iron and steel production

Iron production requires these raw materials: iron ore coal and stone (LIMESTONE) Steel production requires: iron steel scrap flux ("lime" - calcined limestone)

The process of iron and steel making

IRON MAKING

begins as iron ore, which is melted in a blast furnace and blown through with air. Then it is manipulated so Coke is the partially graphitized solid residue left after the volatile components of bituminous coal are removed by heating in coke ovens. At regular intervals, ore, coke and stone are introduced through the top of the blast furnace. As they slowly descend down the furnace shaft, these materials ("burden") are heated by rising hot gases. The carbon monoxide in these gases reacts with the iron oxides in the ore to form metallic iron and carbon dioxide. The iron formed melts and, as it percolates through the coke column, dissolves carbon. By the time it reaches the hearth, it is saturated with carbon, and it also contains silicon, phosphorus, manganese and sulphur. The stone and ore form a low-melting, free-running liquid slag, which absorbs most of the sulphur entering the furnace (coke is the main sulphur source). Liquid slag, composed of gangue minerals and oxide components of stone, floats on the liquid iron and is separated from the molten metal during furnace tapping. The coke does not melt; it burns on contact with the pressured, preheated air ("blast") entering through the tuyres located just above the hearth.as to limit its content of carbon and other impurities

Direct Reduction Several solid-state reduction processes have been developed in which iron ore is converted to metallic iron without melting. Because there is no separation of iron from gangue in the reduction facility, high-grade ores or concentrates (>90% Fe) must be used. Many of these solid-state processes use natural gas as the fuel and as the reducing agent (carbon monoxide and hydrogen). Sidbec-Dosco operates such a process, known as the Midrex Process, at Contrecoeur, Qu. Solid-state reduced ore and/or pellets, known as DRI (Direct Reduced Iron), are melted in electric arc furnaces and converted to steel in the same way as scrap metal. During the steelmaking process, the gangue in DRI is removed; the gangue minerals contained in DRI combine with the added lime to form a fluid slag. DRI is superior to scrap in purity and uniformity of composition but these benefits come at a higher cost.

STEEL MAKING

Steel is manufactured by the chemical reduction of iron ore, using an integrated steel manufacturing process or a direct reduction process. In the conventional integrated steel manufacturing process, the iron from the blast furnace is converted to steel in a basic oxygen furnace (BOF). Steel can also be made in an electric arc furnace (EAF) from scrap steel and, in some cases, from direct reduced iron. BOF is typically used for high-tonnage production of carbon steels, while the EAF is used to produce carbon steels and low tonnage specialty steels. An emerging technology, direct steel manufacturing, produces steel directly from iron ore. This document deals only with integrated iron and steel manufacturing; that on Mini Steel Mills addresses the electric arc stee process and steel finishing processes. Steel manufacturing and finishing processes discussed in that document are also employed in integrated steel plants. In the BOF process, coke making and iron making precede steel making; these steps are not necessary with an EAF. Pig iron is manufactured from sintered, pelletized, or lump iron ores using coke and limestone in a blast furnace. It is then fed to a BOF in molten form along with scrap metal, fluxes, alloys, and high-purity oxygen to manufacture steel. In some integrated steel mills, sintering (heating without melting) is used to agglomerate fines and

Types of iron and steel Cast

iron is a type of iron that has a great structural strength. example: cook wares (iron pans) iron If all the carbon is removed from the iron to give high purity iron, it is known as wrought iron. Wrought iron is quite soft and easily worked and has little structural strength. example: decorative gates and railings, but these days mild steel is normally used instead.

Wrought

Mild steel-is iron containing up to about 0.25% of carbon. The presence of the carbon makes the steel stronger and harder than pure iron. The higher the percentage of carbon, the harder the steel becomes.-used for lots of things - nails, wire, car bodies, ship building, girders and bridges amongst others.

High carbon steel -contains up to about 1.5% of carbon. The presence of the extra carbon makes it very hard, but it also makes it more brittle. High carbon steel is used for cutting tools and masonry nails (nails designed to be driven into concrete blocks or brickwork without bending).

Special steels These are iron alloyed with other metals

For example:

stainless steel titanium steel manganese steel