Procedure

The siemens-martin process is a technical advancement that up to then well-known possibilities of the steelmaking in substantial difference consists of the fact that the temperature in the furnace up to 1800 is increased "°C and liquid steel is produced. As fuel generator gas or oil serves. The original capacity of the Siemens-Martin open-hearth furnaces of under 10 t tapping mass was increased in the course of the development with liquid employment in the USA and Russia on over 600 t.

In order to produce out in the blast furnace for won pig iron steel, the contained accompanying elements must be removed such as carbon, manganese, silicon, phosphorus and other one. That is done via the carbon elimination in such a way specified. The escort substances are oxidized and to escape either gaseously (e.g. CO2) or swim as cinder of firm oxides on the liquid steel.

With the siemens-martin process the oxidative effect is reached by the addition of a certain portion of scrap iron, pig iron ores or lime, the oxygen to the melt to deliver. This firm employment is brought into hollows by means of Chargiermaschinen into the open-hearth furnace. With the liquid employment the pig iron is tilted over a gutter into the open-hearth furnace.

Usually the open-hearth furnace is usually combined with the Siemens regenerativ firing, which is accommodated in an underlying chamber. During the regenerativ firing in regeneration chambers the gaseous fuels are preheated by the exhaust gases from the furnace, in order to achieve the necessary temperature from 1800"°C to. Also the hot flaming gases have oxidative effect and directly into the melt are led.

Technological operational sequence

The fusion process is divided into several sections, which are to be separated not strictly:

1. Furnace care: Torkretieren of the top furnace, cleaning of the and front walls, control of the measuring technique (approx. 0.5 h)
2. Begin: Chargieren of the metallic employments and additives for the cinder formation (approx. 2 h)
3. Melt: Liquefy the employment (approx. 3.5 h)
4. Finish: Work for adjustment the tap analysis and tapping temperature (approx. 1.5 h)
5. Deoxidizing and alloyage
6. Tap with reaching the necessary temperature and analysis (approx. 6 - 17 min)

Total time approx. 8 h

Immediately after the tap pouring the liquid steel takes place in mold after solidifying the blocks/slabs to the subsequent treatment in the rolling mill is transported.

Structure of a Siemens-Martin open-hearth furnace

The Siemens-Martin open-hearth furnace consists of waiter and lower furnace.

The top furnace is the bloom and/or stove area, in which the metallic employment (scrap iron) is melted. Individual parts of the top furnace are the stove, the the front and rear wall, heads and tapping spout beside the structural steelwork consist the furnace predominantly of fireproof of material burner tips with gas and draft of air serve for the heating/melting Rohmaterials.Die filling effected with a Chargierkran on the

In the lower furnace are the clinkering and regenerativ chambers. In the cinder chambers the dust and cinder particles are taken up. In the regenerativ chambers by the utilization of the exhaust gas heat the combustion air and/or the generator gas is preheated. The chambers are brick-lined with a Gitterung from fireproof material. Advantage: By the regenerativ firing the energy contained in the exhaust gases for preheating the heating gases and air used, for this is necessary periodic switching of the chambers in 8 to 20 minute intervals. The control/change-over takes place from the control stand. Lower furnace and fire-place are connected by channels.

History

In the year 1856 Friedrich Siemens had announced a patent on its invention of the regenerativ furnace. This new furnace was based on a system for the production of highest temperatures by preheating gas and air. William Siemens experimented with it several Jahre.So this invention was also important already, did not succeed it to the Siemens brothers first not to manufacture liquid steel because at the reached temperatures of 1600 "°C also the brick lining of the furnace melted. Friedrich Siemens would successfully use the procedure of the regenerativ furnace with the production of glass and became thereby largest glass manufacturer of Europe.

In France the experts for smelting Pierre and Emile Martin (father and son) became attentive to the large advantages of the regenerativ furnace and acquired from William Siemens design and license for the operation Ofens.Den of the Martins succeeded the break-through with application, because they used temperature-steadier stones for the Ofenzustellung. The procedure for the steelmaking in the sour, regenerativ fired reverberatory furnace was born.

the Martins for its outstanding steel and the brothers Siemens for the furnace highest honors received 1867 on that to Paris world exhibition.

The siemens-martin process was over 100 years one of the most important technologies for the steelmaking. The economic meaning of the siemens-martin process lies in the characteristic of the high scrap iron employment.

The era of the Siemens Martin steel production began on 8 April 1864 in the French place Sireuil. Into Germany the first Siemens-Martin open-hearth furnaces went 1869 into meals with Alfred Krupp and into Berlin into enterprise; about at the same time in England, Austria, Sweden, Italy and also in North America. At the beginning 20. Century were overcome the development and initial difficulties.

Starting from 1915 the portion of the Siemens Martin steel rose in Germany to over 50%: End of the 40's world-wide already were 75%. In the year 1965 highest production on a worldwide scale with 278 million tons was reached. Afterwards the production numbers decreased/went back strongly.

1985 were already no longer considerable and only the portion of Siemens Martin steel in Western Europe in Eastern Europe and China meaning.

The end of the era of the Siemens-Martin open-hearth furnaces

In Western Europe the siemens-martin process was displaced by the ld-process, is still isolated used to a large extent in the USA and Russia the procedure. Dominating in the competition of the steelmaking are today the converter and the electrical furnace.

The last Siemens-Martin open-hearth furnace in Western Europe is in Brandenburg to the Havel. In the autumn 1990 with the retreating longwall system of the Siemens-Martin open-hearth furnaces in the steel plant Brandenburg was begun, before the work with the last tap was shut down on 13 December 1993. Today it is the industrial museum Brandenburg, there is now also

The last Siemens-Martin open-hearth furnace in Western Europe

The former Siemens-Martin open-hearth furnace XII went on 12 October 1967 in the VEB stealing and rolling mill Brandenburg into operatingoriginal as attempt furnace should with it point results be achieved. The research contract for this read: To test "“the new design features and technologies up to production-ready ones and to achieve optimal achievement and result indices, those the world conditions with full-oil-heated SM-furnaces under the conditions of the firm employment and the application of oxygen"”. The results should be used for the modernization of all Brandenburger SM-furnaces. A characteristic was from the outset that furnace XII with a sheet metal fire-place was operated. 1968 were used the furnace however as No. XII for the fulfilment of the Planaufgaben and thus its task as research furnace was obstructed. It appeared that the furnace would not achieve the planned parameters particularly during the furnace achievement, with the heat consumption, with the furnace durability and at the repair times; on the development of the furnace therefore one continued to work. Since the given national plan editions for the steel plant were not reached, 1970 began a comprehensive were reconstruction-begun with the furnace XII. 1975 was converted all 12 furnaces in the stealing and rolling mill.

Design features and the substantial changes

• Top furnace with hanging retaining structure in segmental construction according to the March Boehlens principle
• Introduction of the large, two-piece cinder cars
• Air circulation for the top furnace cooling in the structural steelwork
• Enlargement of the hearth area on 83 m
• Development of stove tub series
• Installation of the two-stage regenerativ chambers lying next to each other
• Modern exhaust gas slide valves
• Full oil heating

Related links

• Industrial museum Brandenburg

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