Tap hole drilling machine for blast furnace, drill bit for use i

Details Tap hole drilling machine for blast furnace, drill bit for use i Tap hole drilling machine for blast furnace, drill bit for use i

1999-01-07

2000-07-11

Kastler, Scott

Metallurgical apparatus

Process

Plugging or tapping

266 46, 266271, C21B 712, C21B 710

Patent

active

060868163

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a tap hole drilling machine for producing a molten iron in a blast furnace molten iron making process. The present invention further relates to a drill bit for use in the tap hole drilling machine, and a tap hole drilling method. Particularly, the present invention relates to a tap hole drilling machine, a drill bit for use in it, and a tap hole drilling method, in which a high pressure nitrogen gas is used as a carrying gas for the tap hole drilling, and water mist mixed with cold water is spouted to cool the drill bit, so that the refractory material of the tap hole can be speedily drilled, thereby efficiently carrying out the tap hole drilling operation.
2. Description of the Prior Art
Generally in the blast furnace operation, as shown in FIG. 1, a plurality of tap holes 104 which are formed on the bottom of a blast furnace 100 are either periodically drilled by using a tap hole drilling machine 110, or the tap holes are drilled by using a round bar and by hitting by means of a hammer (not shown in the drawings). Then a slag 101 and a molten iron 120 are tapped through the tap hole 104.
The tap holes 104 are variously different depending on the blast furnace 100, but generally the depth from the blast furnace shell 100a to the inner region of the blast furnace is about 3 m.
Generally in a blast furnace 100 having an interior capacity of 3000 m.sup.3 or more, there are 3-4 tap holes 104 in a blast furnace 100. Among them, one is periodically repaired, while 2-3 of them are used in turns. Generally, the molten iron tapping time is 120-150 minutes.
Now the operation of the blast furnace will be described in detail. That is, the molten iron 120 and the slag 101 are tapped through the tap hole 104 which is formed in a tap hole wall 105 of FIG. 1. Upon completion of the tapping of the molten iron 120 and the slag 101, the tap hole 104 is closed by means of a refractory material 103. Under this condition, the refractory material 103 is calcined by the high pressure and the high temperature of the internal region of the blast furnace 100, and therefore, the strength of the refractory material is increased. When an operation through one tap hole 104 is completed, another tap hole is used, and in this manner, all the tap holes 104 are ultimately used.
Thus, upon completion of the operation through one tap hole 104, the relevant tap hole 104 is closed. As the time elapses, the refractory material 103 which has been closing the tap hole 104 is more calcined. Therefore, when the tap hole 104 is drilled for reuse, the drilling becomes very difficult.
Meanwhile in the conventional drilling operation, the tap hole 104 of the wall 105 is drilled by using a drill rod 106 and drill bit 107 which is fitted to a main body 118 of the tap hole drilling machine. Or the tap hole 104 is drilled by hammering and by using a round bar.
Under this condition, the refractory material 103 has been calcined and hardened within the blast furnace 100, and therefore, due to impacts of the drilling and the hammering, cracks are easily formed. Consequently, the refractory material 103 is detached in the blast furnace 100, and a gap is formed. Therefore the melt is leaked through the gap, and this leakage molten iron forms a solidified iron (to be called "inside crack") P, with the result that the drilling is rendered significantly more difficult. Accordingly, in the region of the solidified iron P, the drilling efficiency is significantly lowered.
Therefore, in the case where the drilling or hammering becomes difficult, a last means is applied in such a manner that oxygen is injected through a pipe (not shown in the drawings), and that the solidified iron P is dissolved, thereby opening the tap hole 104.
However, in the case where oxygen is injected, the flame of oxygen expands the tap hole 104 or damages the tap hole 104. Further, the opening time for the tan hole 104 is extended, and therefore, the molten iron tapping time is shortened, with the result

REFERENCES:
patent: 4456083 (1984-06-01), Gozeling et al.
patent: 4895349 (1990-01-01), Broom
Japanese Patent Abstract No. JP358224104A Dec. 1983.
Japanese Patent Abstract No. JP362107008A May 1987.

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