Abstract An electric arc furnace has a side wall lining with at least one portion bombarded by the arc flare from one of the furnace arcing electrodes. A magnet is positioned on the outside of this portion and ferro-magnetic particles are fed to its inside, the magnet forming a magnetic flux field traveling through this lining portion and on the latter''s inside magnetically holding the particles to form an arc flare shield protecting this portion''s inside from the arc flare. As the particles heat to their Curie point temperatures, they become non-magnetic and fall into the melt of the furnace, a supply of fresh and relatively cold particles being fed to the flux field as required to maintain the effectiveness of the arc flare shield formed by the particles. The wall thickness of this portion is reduced from its outside inwardly to form a recess in its outside and in which the magnet is positioned to reduce the distance the flux field must travel to the inside to hold the ferro-magnetic particles. Between the magnet and this thin wall portion a water cooled plate is positioned to cool the thin wall portion of the lining. In this way the travel path of the magnetic flux is reduced in length without risking possible overheating of the lining, permitting the use of a less powerful magnet construction, this being an electromagnet and requiring electric solenoids, a core or cores with pole pieces and a suitable mounting arrangement. A temperature measurement sensor is installed in the thin wall of the lining portion protected by the flare shield, and equipment is provided for controlling the feed rate of the ferro-magnetic particles which form the shield, automatically in response to the temperature measurements obtained from this sensor, this assuring maintenance of the effectiveness of the shield. The water-cooled plate may be made of non-magnetic metal to avoid interference with the flux travel through the plate.
An electric arc furnace comprising at least one electrode having an end forming an arc producing an arc flare, a side wall lining having at least one portion having an inside positioned to be bombarded by said flare, said portion having an outside, a magnet having pole-piece ends on said outside forming a magnet flux field traveling through said portion and beyond said inside and on said inside holding ferro-magnetic particles forming a flare shield until the particles are heated to their Curie point temperatures, and a feeder for feeding said field with replacement ferro-magnetic particles at temperatures lower than their Curie point temperatures; wherein the improvement comprises said lining having an outer surface in which a recess is formed at said portion so that said portion has a reduced wall thickness through which said flux field must travel, and means between said magnet and recess for water-cooling said portion of reduced wall thickness.
Claim 2
Dependent Claim
154 words
An electric arc furnace comprising at least one electrode having an end forming an arc producing an arc flare, a side wall lining having at least one portion having an inside positioned to be bombarded by said flare, said portion having an outside, a magnet having pole-piece ends on said outside forming a magnet flux field traveling through said portion and beyond said inside and on said inside holding ferro-magnetic particles forming a flare shield until the particles are heated to their Curie point temperatures, and a feeder for feeding said field with replacement ferro-magnetic particles at temperatures lower than their Curie point temperatures; wherein the improvement comprises said lining having an outer surface in which a recess is formed at said portion so that said portion has a reduced wall thickness through which said flux field must travel, and means between said magnet and recess for water-cooling said portion of reduced wall thickness.
Claim 3
Dependent Claim
19 words
The furnace of claim 1 in which said flare shield is formed by iron ore particles in powder form.
Claim 4
Dependent Claim
17 words
The furnace of claim 1 in which said magnet pole piece ends are inside of said recess.
Claim 5
Dependent Claim
27 words
The furnace of claim 3 in which said means is a water-cooled non-magnetic plate positioned against said outside between the latter and said magnet pole piece ends.
Claim 6
Dependent Claim
29 words
The furnace of claim 4 in which said feeder has a feed rate controller and means for actuating said controller automatically in response to the temperature of said portion.