US 4,456,476 A · Continuous steelmaking and casting

Abstract

In a continuous steelmaking process, a molten metal bath is maintained within a rotary furnace heated by oxy-fuel burners at the charge and discharge ends. Metallic iron charge material such as iron and steel scrap or sponge iron is preheated primarily by heat transferred from the furnace exhaust gases, on an enclosed recuperative conveyor before being introduced through the charge end opening. Molten metal is withdrawn through a siphon tube submerged in the bath through the furnace discharge end opening into a vacuum chamber which is part of an integral vacuum chamber-tundish combination incorporating a molten metal column under vacuum in one leg and a molten steel tundish casting pool under atmospheric pressure as the other leg, connected via a submerged channel. As steel is cast out of the tundish through a submerged nozzle, it is replenished by way of the column from vacuum-induced flow through the siphon tube, metal surface levels in column and tundish remaining substantially constant once casting has been established. Several means are provided for regulating withdrawal and casting rate, including the use of slide-gate valves and varying the vacuum pressure.

Claims23

Dependent claims

A process for continuous steelmaking and casting from a rotary furnace, comprising the combination of the following steps:

(a) maintaining a molten metal bath within a rotary furnace having an axial discharge end opening with the bath surface exposed to substantially atmospheric pressure;
(b) maintaining an enclosed molten metal column external to the furnace having the top surface exposed to a controlled vacuum pressure and confined within an enclosed vacuum chamber having a siphon tube having the exit end connecting into said chamber, and the entry end inserted through the axial furnace discharge opening down through the bath surface and submerged in said bath;
(c) maintaining a molten steel casting pool in a steel casting tundish in direct communication with said column via a submerged channel, with the top surface of said pool at a level higher than said column bottom level extremity and subjected to a substantially constant reference gas pressure, for example, atmospheric pressure by allowing flow of metal from within said column into said casting pool by way of said submerged channel connecting between them;
(d) allowing pouring of molten steel through at lest one submerged nozzle opening from said casting pool, directly into a casting mold without transfer to an intermediate vessel;
and
(e) withdrawing molten metal from said bath into said column under the influence of said vacuum pressure via said siphon tube at a rate providing for continual replenishment of the steel pouring from said casting pool for casting.

3 more elements

A process for continuous steelmaking and casting from a rotary furnace, comprising the combination of the following steps:

(a) maintaining a molten metal bath within a rotary furnace having an axial charge end opening and an axial discharge end opening with the bath surface exposed to substantially atmospheric pressure;
(b) maintaining an enclosed molten metal column external to the furnace having the top surface exposed to a controlled vacuum pressure and confined within an enclosed vacuum chamber having the exit end connecting into said chamber, and the entry end inserted through the axial furnace discharge opening down through the bath surface and submerged in said bath;
(c) withdrawing molten metal from said bath into said column under the influence of said vacuum pressure via said siphon tube;
(d) allowing flow of metal from within said column out through a submerged opening under the influence of gravity at an average rate corresponding to the rate of withdrawing molten metal from said bath;
(e) conveying metallic iron charge material along a preheater conveyor having the exit end discharging directly into the furnace through said charge end opening and covered substantially along its length by an enclosure directly connecting with the furnace charge end in direct communication with the interior of said furnace;
(f) introducing heat by combustion from an oxygen-fuel burner directed through said charge end opening for melting said metallic from charge;
(g) introducing heat by combustion from an oxygen-fuel burner directed through said discharge end opening for maintaining said metal bath in a molten condition at controlled temperture;
(h) effecting flow of hot combustion products within said furnace countercurrent to the general charge movement out through said charge end opening and directly into said enclosure to pass in continuous contact with said charge on said conveyor without separate hot gas passageways between furnace and preheater, in a manner to effect continuous preheating of said charge material;
and
(i) discharging preheated charge material from said conveyor into said furnace through said charge end opening at an average rate corresponding to the average rate of said withdrawing molten metal from said molten metal bath.

7 more elements

A process for continuous steelmaking and casting from a rotary furnace comprising the steps of:

inserting the entry end of a refractory siphon tube beneath the surface of a molten metal bath contained in a rotary furnace, connecting the exit end of the siphon tube into the interior of an enclosed vacuum chamber which is in direct communication with a steel pouring tundish near said furnace, temporarily blocking communication between the interior of the enclosed vacuum chamber and tundish, withdrawing molten metal into said vacuum chamber via said siphon tube under the influence of controlled vacuum pressure within said chamber forming a molten steel column within said vacuum chamber, enabling communication to resume between the interior of the enclosed vacuum chamber and tundish so that metal within the vacuum chamber can flow into the tundish, allowing a steel pool within the tundish to increase to a pre-selected depth above at least one submerged nozzle opening leading from the tundish, and continuously maintaining the molten steel pool within the tundish to said depth by continual replenishment of the poured metal with metal supplied from the furnace through the siphon tube and through the enclosed vacuum chamber to enable pouring from the tundish over protracted periods of casting.

Dependencies are inferred from the claim text.

Continuous steelmaking and casting

Life of this patent

Continuous steelmaking and casting

Life of this patent

Abstract

Claims23