Industrial electric heating furnaces – Electroslag remelting device
Reexamination Certificate
2000-01-26
2001-04-17
Hoang, Tu Ba (Department: 3742)
Industrial electric heating furnaces
Electroslag remelting device
C373S045000, C373S083000, C373S115000, C266S045000
Reexamination Certificate
active
06219370
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a channel arrangement for discharging molten metal from a smelting furnace.
Discharging molten metal from a smelting furnace, such as a blast furnace or a cupola furnace, is referred to by the technical term “tapping”. The liquid metal together with the liquid running slag is guided from the smelting furnace through a channel made of fireproof material. The channel is disposed in a thick lining made of refractory clay brick which is generally referred to as “lining”.
The high thermal and mechanical stress caused by the annealing liquid material which is conducted through the channel during the tapping, severely stresses the inner surfaces of the channel. This causes increased wear in the so-called slag zone in the upper region of the channel as well as in the so-called pig-iron zone in the lower region. Hence, the channel has to be replaced according to the severity of the erosion, typically in regular intervals when the sidewalls are eroded by about one half of their thickness.
The channel is then taken out of service and repaired. With conventional methods, the worn-out regions are broken away. This can be done partly with machines, partly manually using jackhammers. Thereafter, the channel is from-stripped from inside and the region to be repaired is filled with a pourable compound of a fireproof material.
Several days, including the time required for the pourable compound to dry, have to be set aside before the furnace can be tapped again. Repairing the channel and removing the material from the channel is labor-intensive and time-consuming. Accordingly, the costs associated with the conventional methods tend to be quite high.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide—based on the state of art—a channel arrangement for discharging molten metal from a smelting furnace which significantly reduces the time required to rebuild the worn-out channel, thereby reducing the overall cost.
The object is solved by a channel arrangement which includes a channel with two sidewalls and a channel bottom made of a fireproof material, and is arranged inside a formwork trough. The lateral formwork walls are provided with a transversely moveable push wall. A receiving space which can be filled with a hardenable fireproof material is provided between the formwork walls and the sidewalls.
By employing the channel arrangement according to the invention, the process of reconditioning the channel can be significantly simplified. According to one aspect of the invention, the replacement sidewalls are held in reserve behind the sidewalls of an operational channel. The replacement sidewalls are created by filling the receiving space with the fireproof material, in order to exploit hereby the operational channel and the sidewalls of the channel as form.
The steps associated with this process can be described as follows:
In the initial state, a first channel is poured in a conventional manner. The push walls form here the lateral formwork. After the channel has hardened, the push walls are moved away from the sidewalls of the channel towards the lateral formwork walls of the formwork trough. The receiving space which is thereby formed between the push walls and the sidewalls of the channel can subsequently be filled with a fireproof material.
As soon as the channel in operation is so severely worn out as to require a replacement, the channel is taken out of service and cleaned by stripping the bottom portion. The remaining sections of the sidewalls together with the replacement sidewalls located in the receiving space are then moved forwardly by a predetermined distance. The bottom of the channel is then filled with fireproof material, as is the receiving space produced behind the replacement sidewalls.
The fireproof material can be, for example, poured high-temperature concrete, pourable thixotropic material, low and ultra-low cement concrete, as well as tamping material and injection material. Dry compounds and so-called back-fill materials can also be used.
The channel arrangement according to the invention saves significant time and effort, while at the same time requiring much less fireproof material, since the already worn material remains in the aggregate and functions as a formwork for the newly formed or repaired lining. This aspect also results in significantly lower costs.
Since less pourable material is required, the disposal costs can also be reduced.
According to an advantageous embodiment of the channel arrangement of the invention, the channel is arranged on a base plate inside the formwork trough. With this arrangement, the region of the sidewalls facing the base can be more easily cleared, and the replacement sidewalls can be more easily moved on the base plate.
According to another feature of the invention an adjustment mechanism can be used to move the push walls. Different systems can be implemented. For example, the system can be implemented using a cylinder and cylinder rods or threaded adjustment spindles.
According to yet another feature of the invention the inner surfaces of the formwork trough are provided with an insulating lining. In practice, an insulation made of, for example, refractory clay bricks can be arranged underneath the base plate.
REFERENCES:
patent: 3735010 (1973-05-01), Turpin
patent: 3973076 (1976-08-01), Scott, Jr. et al.
patent: 5968447 (1999-10-01), Pavlicevic et al.
patent: 6090340 (2000-07-01), Boonacker et al.
Feiereisen Henry M.
GfT Gesellschaft für Feuerfest-Technik m.b.H.
Hoang Tu Ba
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