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 A steel mill or steelworks is an industrial plant for the manufacture of  steel.

Steel is an alloy of iron and carbon. It is produced in a two-stage process. First, iron

ore is reduced or smelted with coke andlimestone in a blast furnace, producing molten iron which is

either cast into pig iron or carried to the next stage as molten iron. In the second stage, known

as steelmaking, impurities such as sulfur , phosphorus, and excess carbon are removed

and alloying elements such as manganese, nickel, chromium and vanadium are added to produce

the exact steel reuired. Steel mills then turn molten steel into blooms, ingots, slabs and sheet

through casting, hot rolling and cold rolling.

In the late !"th and early #$th centuries the world%s largest steel mill was the &arrow 'ematite Steel

(ompany steelworkslocated in &arrow-in-Furness, )nited *ingdom. +oday, the world%s largest steel

mill is in wangyang, South *orea.!#

Contents

  hide

• ! Integrated mill

• # /inimill

• 0 See also

• 1 2eferences

• 3 Further reading

• 4 5xternal links

Integrated milledit

6lan of the 7ackawanna Steel 6lant ca. !"$0, showing the various elements of an integrated steel mill.

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&last furnaces of +8inec Iron and Steel 9orks

Interior of a steel mill

 An integrated steel mill has all the functions for primary steel production:

• iron making ;conversion of ore to liuid iron<,

• steelmaking ;conversion of pig iron to liuid steel<,

• casting ;solidification of the liuid steel<,

• roughing rolling=billet rolling ;reducing si>e of blocks<

• product rolling ;finished shapes<.

+he principal raw materials for an integrated mill are iron ore, limestone, and coal ;or coke<. +hese

materials are charged in batches into a blast furnace where the iron compounds in the ore give up

excess oxygen and become liuid iron. At intervals of a few hours, the accumulated liuid iron is

tapped from the blast furnace and either cast into pig iron or directed to other vessels for further

steelmaking operations. 'istorically the &essemer process was a ma?or advancement in the

production of economical steel, but it has now been entirely replaced by other processes such as

the basic oxygen furnace.

/olten steel is cast into large blocks called @blooms@. uring the casting process various methods

are used, such as addition of aluminum, so that impurities in the steel float to the surface where they

can be cut off the finished bloom.

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&ecause of the energy cost and structural stress associated with heating and cooling a blast

furnace, typically these primary steelmaking vessels will operate on a continuous production

campaign of several years duration. 5ven during periods of low steel demand, it may not be feasible

to let the blast furnace grow cold, though some ad?ustment of the production rate is possible.

Integrated mills are large facilities that are typically only economical to build in #,$$$,$$$ ton per

year annual capacity and up. Final products made by an integrated plant are usually large structural

sections, heavy plate, strip, wire rod, railway rails, and occasionally long products such

as bars and pipe.

 A ma?or environmental ha>ard associated with integrated steel mills is the pollution produced in the

manufacture of coke, which is an essential intermediate product in the reduction of iron ore in a blast

furnace.

Integrated mills may also adopt some of the processes used in mini-mills, such as arc furnaces and

direct casting, to reduce production costs.

9orld integrated steel production capacity is at or close to world demand, so competition between

suppliers results in only the most efficient producers remaining viable. 'owever, due to the large

employment of integrated plants, often governments will financially assist an obsolescent facility

rather than take the risk of having thousands of workers thrown out of ?obs. not specific enough to verify 

Minimilledit

 An ingot of steel entering a rolling mill

 A minimill is traditionally a secondary steel producerB however, Cucor  ;one of the world%s largest steel

producers<, as well as one of its competitors, (ommercial /etals (ompany ;(/(< use minimills

exclusively. )sually it obtains most of its iron from scrap steel, recycled from used automobiles and

euipment or byproducts of manufacturing. irect reduced iron ;2I< is sometimes used with scrap,

to help maintain desired chemistry of the steel, though usually 2I is too expensive to use as the

primary raw steelmaking material. A typical mini-mill will have an electric arc furnace for scrap

melting, a ladle furnace or vacuum furnace for precision control of chemistry, a strip or

billet continuous caster  for converting molten steel to solid form, a reheat furnace and a rolling mill.

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Driginally the minimill concept was adapted to production of bar products only, such

as concrete reinforcing bar , flats, angles, channels, pipe, and light rails. Since the late !"E$s,

successful introduction of the direct strip casting process has made minimill production of strip

feasible. Dften a minimill will be constructed in an area with no other steel production, to take

advantage of local resources and lower-cost labour. /inimill plants may speciali>e, for example,making coils of rod for wire-drawing use, or pipe, or in special sections for transportation and

agriculture.

(apacities of minimills varyB some plants may make as much as 0,$$$,$$$ tons per year, a typical

si>e is in the range #$$,$$$ to 1$$,$$$ tons per year, and some old or specialty plants may make as

little as 3$,$$$ tons per year of finished product. Cucor (orporation, for example, annually produces

around ",!$$,$$$ tons of sheet steel from its four sheet mills, 4,$$,$$$ tons of bar steel from its !$

bar mills and #,!$$,$$$ tons of plate steel from its two plate mills.

Since the electric arc furnace can be easily started and stopped on a regular basis, minimills can

follow the market demand for their products easily, operating on #1 hour schedules when demand is

high and cutting back production when sales are lower.