Smelting reduction furnace
A smelting reduction furnace (engl .: S ubmerged A rc (-resistance) F urnace , SAF) is a special form of the electric arc furnace .
Application area
Typical areas of application are the melting of alloy components , ferro alloys or so-called aggregates . The products from smelting reduction furnaces are mainly used in metallurgy , for example to convert undesired constituents of a melt into slag and thus remove them from the melt.
Nickel , calcium carbide or metallurgical silicon are smelted on a larger scale , with the furnaces being specially designed for the molten material.
Another application of melt-reduction furnaces is the reaction of calcium phosphate in the form of minerals phosphorite or apatite with coke and quartz sand to white at temperatures around 1400 ° C phosphorus to win.
Heat generation
In contrast to the electric arc furnace with the unloaded between the weld and the electrode arc , the electrode is immersed in the slag. The heating power arises primarily from the flow of current through the slag, which acts as an electrical resistance, as well as partly from arcs that form inside the slag. The melt itself does not have to be electrically conductive.
The 3-electrode version supplied with three-phase alternating current in star connection is common , with round furnaces the electrodes themselves are arranged in an equilateral triangle.
If the melting material is electrically conductive, the number of electrodes can be reduced to one. Such ovens are operated with direct current; the melt represents the opposite pole.
Either the Söderberg electrode or screwable, pre-baked electrodes made of carbon with binders are commonly used as the electrode design.
literature
- DEC Corbridge: Phosphorous: An Outline of Its Chemistry, Biochemistry and Technology . 5th edition. Elsevier Science Ltd., 1995, ISBN 978-0-444-89307-9 .