SE448184B - DC arc furnace for metal oxide redn. - Google Patents

Abstract

A d.c. arc furnace, of the type in which powdered material is fed through a through- channel in the electrode(s), has a roof which, in addition to an insulating portion around the electrode(s), comprises a plane suspended portion defining the upper limit of an exhaust gas outlet, the lower limit of the outlet being defined by a threshold. The furnace is useful for melt redn. of oxides of e.g. iron, nickel, cobalt and chromium and materials contg. such oxides, by the methods of GB1455221 and 1467542. The design provides ample space at the side of the furnace vessel for the gas outlet thus reducing the gas flow rate and consequent rapid wear of the furnace lining, esp. at the outlet. The plane roof portion reverses the direction of upwards gas flow thus returning dust to the lower part of the furnace. Additionally, the roof is very easy to repair and can have a constant internal height close to the theoretical maximum height. Only a minor portion of the electrode(s) may extend into the furnace to reduce the risk of electrode rupture.

Description

The invention relates to one or more gas outlets for this. gas at an arc DC furnace, and the invention is characterized in that the gas outlet is drawn between a lower part of the furnace wall, formed as an edge or threshold, and the furnace vault, and after the threshold pulled downwards and then at an angle upwards, wherein in said angle lower part is arranged a dust separator or a dust trap. It prevents unnecessary radiation losses from the oven Via ï Viaet Via ß fl- SUÜHGEII and by suitable sizing of the sockets you can get a low gas velocity with accompanying low lining wear. Dust from the oven dish does not disappear with the gas but stays in the said. dust trap, and radiation from the 'counties 85-1' GJ into the surroundings and does not unnecessarily heat the walls of the gas outlet.

Inventions: are further exemplified in the accompanying figures, of which. figure 1 shows a direct current arc furnace in vertical section and figure 2 corresponding, seen from above, partly in horizontal section.

The figures show a DC arc axis with at least one graphite or Söderberg electrode 1 with central feed channel 2 for metal oxide such as iron oxide or similar oxide containing powders (e.g. iron ore) and carbon, boiling or other carbonaceous solid reducing agents (may also be at least partially In this way, the melt is added to another and possibly slag formers, such as lime.

Arranged in the bottom of the ignition channel 2 is a melting coil 4, in contact with a bottom contact S. The bottom contact 5 is connected as an anode and the electrode / electrodes 1 as a cathode to a direct voltage source (not shown).

The furnace electrode 1 is relatively long, for example 15 m with a smaller part, 5 m, in the furnace edge. An arc is created between electrode 1 and melt, and the slag is driven to the side. Oxide is reduced in duct, in arc and / or in molten to pure metal, such as pig iron, and gas CO is formed, as well as any hydrogen gas, which is to be fed to a gas supply system for energy use.

The gas outlet, one or more 6, is drawn over a threshold in the ugis wall, obliquely downwards (see at B) in order to prevent rectilinear gas escape with accompanying large dust escape from the oven, radiation losses, etc.

The outlet 6 is continued by an upwardly directed part 9, and at the angle at its lower part a dust separator 10 or dust trap is arranged, where dust (oxide or metal) is separated and possibly returned to the process.

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Claims (2)

The angled gas outlet 7 is designed as a steam boiler unit or precursor to a trailing steam boiler. To this steam preparation unit, the leachate is led from the previously mentioned suspension devices for the vault tile together with other kiln leachate water and is fed into this unit as preheated steam boiler water. The walls of the outlet, in particular the upper ones 11, are fireproof, and the outlet dimensions are such that the gas velocity therein becomes low. The task of the threshold thus becomes. to prevent dust leakage and to slow down the outlet and reduce radiation loss. Tröekeln 7 can be made of refractory brick and / or stamping compound, possibly with refractory cladding. The gas outlet 6 can also have the same design, but always in such a way that rectilinear gas outlet is made impossible. The device as above can be varied. in many ways within the scope of the following claims. PATENT REQUIREMENTS 1. Apparatus for amelectric reduction of metal oxides in powder form, such as iron oxide, nickel, cobalt, chromium and / or oxides of metals within the iron ore of the periodic table, or such oxides containing materials, such as iron ore slag, and for gas generation, comprising a direct current arc furnace must have at least one electron (1) through the channel (2), aamt aan fan supply to this channel / channels of said powder and reducing agents, such as carbon, coke or other carbonaceous, solid reducing agent and any slag , wherein from the furnace barrel (5) is drawn at least to a hole socket (6) for 1 electrode, arc and / or melt formed gas, characterized in that the gas socket is pulled between a lower part (7) of the furnace wall, formed as an edge or threshold (7), and the furnace arch, and after the threshold pulled downwards and then at an angle upwards, wherein in the lower part of said angle than other atoftavamljara (10) all: an ntaftfälla. Device according to claim 1, characterized in that the gas outlet (6), at least at its upper walls, is clad with refractory material (11).