Open hearth furnaces are one of a number of kinds of furnace where excess carbon and other impurities are burnt out of pig iron to produce steel. Since steel is difficult to manufacture due to its high melting point, normal fuels and furnaces were insufficient and the open hearth furnace was developed to overcome this difficulty. Pig iron is raw iron, the immediate product of smelting iron ore with coke and limestone in a blast furnace. ... Steel making technologies: Bessemer converter LD Process Basic oxygen furnace Electric arc furnace Related topics: Steel Blast furnace This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... The old steel cable of a colliery winding tower Steel is a metal alloy whose major component is iron, with carbon content between 0. ... The melting point of a solid is the temperature at which it changes state from solid to liquid. ...

Technically perhaps, the first primitive open hearth furnace was the Catalan forge, invented in Catalonia in the 8th century, but it is usual to confine the term to certain 19th century and later steelmaking processes, thus excluding bloomeries (including the Catalan forge), finery forges, and puddling furnaces from its application. Catalonia or the Principality of Catalonia (Catalan: Catalunya or Principat de Catalunya ; Spanish: Cataluña or Principado de Cataluña; Aranese: Catalonha or Principautat de Catalonha ; French: Catalogne or Principauté de Catalogne) is a historic region in southern Europe, formerly an independent country, embracing a territory now situated in the... Alternative meaning: Nineteenth Century (periodical) (18th century — 19th century — 20th century — more centuries) As a means of recording the passage of time, the 19th century was that century which lasted from 1801-1900 in the sense of the Gregorian calendar. ... A bloomery is a type of furnace once widely used for smelting iron from its oxides. ... Iron tapped from the blast furnace is pig iron, and contains significant amounts of carbon and silicon. ... Schematic drawing of a puddling furnace The puddling furnace is a metalmaking technology to create wrought iron from the pig iron produced in a blast furnace. ...

The Siemens regenerative furnace

Sir Carl Wilhelm Siemens developed the Siemens regenerative furnace in the 1850s, and claimed in 1857 to be recovering enough heat to save 70-80% of the fuel. This furnace operates at a high temperature by using regenerative preheating of fuel and air for combustion. In regenerative preheating, the exhaust gases from the furnace are pumped into a chamber containing bricks, where heat is transferred from the gases to the bricks. The flow of the furnace is reversed so that fuel and air pass through the chamber and are heated by the bricks. Through this method, an open-hearth furnace can reach temperatures high enough to melt steel, but Siemens did not initially use it for that. Wilhelm Siemens Carl Wilhelm Siemens (en: Charles William Siemens) (April 4, 1823 – November 19, 1883) was a German engineer. ... // Events and Trends Technology Production of steel revolutionised by invention of the Bessemer process Benjamin Silliman fractionates petroleum by distillation for the first time First transatlantic telegraph cable laid First safety elevator installed by Elisha Otis Science Charles Darwin publishes The Origin of Species, putting forward the theory of evolution... Air preheater Airpreheater is a general term and represents any heater designed to heat air. ... Combustion or burning is a complex sequence of chemical reactions between a fuel and an oxidant accompanied by the production of heat or both heat and light in the form of either a glow or flames. ...

The regenerators are the distinctive feature of the furnace and consist of fire-brick flues filled with bricks set on edge and arranged in such a way as to have a great number of small passages between them. The bricks absorb most of the heat from the outgoing waste gases and return it later to the incoming cold gases for combustion.

Open Hearth steelmaking

In 1865, Emile Martin and Pierre Martin took out a licence from Siemens and first applied his furnace for making steel. Their process was known as the Siemens-Martin process, and the furnace as an "open-hearth" furnace. The rapid production of large quantities of basic steel, such as that which is used to construct tall buildings, is the most appealing characteristic of the Siemens regenerative furnace. The usual size of furnaces is 50 to 100 tons, but for some special processes they may have a capacity of 250 tons or even 500 tons. The Siemens-Martin process complemented rather than replacing the Bessemer process. It was slower and thus easier to control. 1865 (MDCCCLXV) is a common year starting on Sunday. ... The old steel cable of a colliery winding tower Steel is a metal alloy whose major component is iron, with carbon content between 0. ... Bessemer converter, schematic diagram The Bessemer process was the first inexpensive industrial process for the mass-production of steel from molten pig iron. ...

Basic oxygen steelmaking or LD process replaced the open hearth furnace. Basic oxygen steelmaking (BOS, Linz-Donawitz-Verfahren, LD-converter) is a method of converting molten iron to steel. ... Basic oxygen steelmaking (BOS, Linz-Donawitz-Verfahren, LD-converter) is a method of converting molten iron to steel. ...

Further reading

• K. Barraclough, Steelmaking 1850-1900 (Institute of Metals, London 1990), 137-203.
• W. K. V. Gale, Iron and Steel (Longmans, London 1969), 74-77.

External links

• Precursors to the Blast Furnace