Daido Tokushuko Kabushiki Kaisha

Kenji Kanada

Noboru Demukai

Tetsuo Okamoto

Saburo Sugiura

Kiyohide Hayashi

Sabro Sugiura

Senji Fujita

Tetuo Okamoto

The specification discloses a ladle furnace apparatus for refining molten steel tapped from a steelmaking furnace therein. There are introduced molten steel and a slag making material into the ladle. The outer and inner lids of the ladle furnace are put on the respective receiving surfaces of the ladle to close the opening thereof. In the interior of the ladle, the slag making material is slagged by arc heating thereby to refine molten steel introduced therein by means of the slag. During the refining process, the suction of gas is carried out from a space formed between the outer lid and the inner lid. Therefore, a dust containing gas generated by reaction of the molten steel and slag enters the space between the outer lid and the inner lid passing through a gap formed between the inner lid and the ladle or electrode holes disposed in the inner lid to be sucked therefrom. Even if the open air enters the apparatus through a gap between the outer lid and the ladle, the open air does not flow inside of the inner lid. Therefore, it is possible to prevent the temperature of slag from being lowered due to the open air. In addition, it is also possible to prevent the refining efficiency of slag on the molten steel from being lowered. Consequently, refining on the molten steel can efficiently be performed.

Ladle furnace

An improvement to a scrap melting method employing an electric arc furnace, which comprises the step of heating the scrap by a powdered coal burner prior to the step of heating the scrap by the electric arc. The burning conditions are controlled so as to reduce the amount of oxidized Fe as well as the amount of NO.sub.x contained in the exhaust gases. In preferred embodiments, a pair of furnaces are employed to heat the scrap alternately by the powdered coal burner and by the electric arc.

Scrap melting method

A powdered coal burner used for directly heating an object to be heated, particularly iron scrap, in a heating vessel. The burner is composed of an oxygen nozzle, a powdered coal nozzle, an air nozzle, disposed concentrically from the center, and a cone which is provided at the end of the opening part of the oxygen nozzle in such a way as to disperse oxygen in a radial direction and burn powdered coal. The burner burns with shortened length of flame, and temperature of the flame is not excessively high.

Powdered coal burner

During the heating of scrap in a container using sulfur-containing fuels for combustion, CaO, Ca(CO).sub.2, or CaCO.sub.3 powder is injected into the container to fix sulfur oxides generated during the combustion mainly as CaSO.sub.4. There is no need for special exhaust gas desulfurization, and, at the same time, slag formation is possible.

Scrap heating method

A method of melting iron scrap using an arc furnace with reduced electric power consumption. In one of a pair of vessels which are arc furnace bodies, melting of the scrap by heat of arc is carried out while a carbonaceous material and oxygen-containing gas are introduced therein to cause oxidation of C to CO to make use of the oxidation heat. Thus formed hot exhaust gas containing CO is introduced to the other vessel of the pair and oxygen-containing gas is added thereto to cause oxidation of CO to CO.sub.2 thereby heating the scrap loaded in the vessel. Melting is further continued by changing the roles of the two vessels to each other. Generation of the CO-containing hot gas can be performed in a separately installed gasification furnace.

Growing community of inventors

Chita, Japan

Kenji Kanada