The present invention relates to equipment and method for tapping molten metal and for controlling the flow out of a furnace used in metallurgy, or out of a corresponding metallurgic vessel.

For tapping molten metal from a furnace, there are developed tapping mechanisms that are described in the patent publications US 3,973,761 and US 5,820,815. In these publications, the technique is based on that the metal contained in the furnace is solidified at the taphole, so that said metal forms a plug, and the flowing of the molten metal out of the taphole is prevented. Among the problems connected to said techniques, let us point out that in the beginning of every tapping step, a frozen metal plug must be opened by a cumbersome method.

According to the prior art, molten copper is tapped from an anode furnace onto the casting equipment by tilting a cylindrical, horizontal anode furnace that is tumable with respect to its lengthwise axis, so that molten copper flows through a continuously open taphole to a chute or a suitable intermediate launder. Several different drawbacks are connected to said technique. Molten copper is easily splashed during the pouring step, and along with the melt, also slag accumulated on the surface of the molten metal is transferred to the chute or the intermediate launder. Current practice often requires that the melt is poured from a considerable height to a wide melt tank, from where the melt is conducted further along the chute.

In connection with the casting of metals, melt is tapped several times per day. Therefore the equipment for tapping melt must be easy to use, and the need for maintenance and connected manual work during usage must be minimal. It is necessary to be able to adjust the flowing of melt rapidly and accurately, according to the operation of the casting machine. The need for achieving reliable and user-friendly equipment is particularly great when tapping and casting metals with a relatively low melting point. Among the targets of application for this kind of equipment, let us point out the casting of aluminum, copper, zinc, lead, tin and alloys thereof, for example.

The object of the present invention is to eliminate the problems connected to the prior art and to achieve a novel mechanism and method for tapping molten metal from a furnace.

The invention is a sliding gate mechanism to be installed in the taphole of a metallurgic furnace or vessel for tapping molten metal from the furnace, said sliding gate mechanism being provided with means for feeding gas into the taphole in order to keep the molten metal in motion and to keep the metal contained in the vicinity of the taphole in molten form.

Remarkable advantages are achieved by means of the invention. By using the invention, it is possible to tap and cast metals with a fairly low melting point as well as their alloys without the risk of the metal being solidified in the taphole even during short breaks in the tapping process. By means of the invention, the jet of the metal tapped or cast can be directed precisely to the desired spot without splashes.

The sliding gate mechanism according to the invention for tapping molten metal into a tapping channel from a metallurgic furnace or vessel includes a counterplate that can be permanently installed with respect to the taphole of the metallurgic furnace or vessel, which counterplate is provided with a flow channel for the flowing of the metal, and with an adjusting plate that is fitted between the counterplate and the plate of the tapping channel, to move slidably with respect to the counterplate, for controlling the flow into the tapping channel. The adjusting plate is provided with at least one flow channel that can be slid between the flow channel of the counterplate and the tapping channel for adjusting the flow of the metal, and the adjusting plate is provided with at least one gas feed channel made of porous material, through which channel gas can be fed to at least one flow channel of the sliding gate mechanism. According to an embodiment of the invention, the element defining the tapping channel is permanently arranged in the adjusting plate. According to another embodiment of the invention, the element defined by the tapping channel is permanently arranged with respect to the counterplate, so that the adjusting plate is arranged to slide with respect to the counterplate and the element defined by the tapping channel.

The element defined by the tapping channel may include or be provided with a suitable melt control pipe for conducting molten metal in a controlled fashion to the desired target, such as a chute, trough or a casting mold.

Gas is fed into the gas feed channel at a sufficient pressure, so that the molten metal is suitably set in motion in the flow channel and in the taphole of the furnace or a corresponding vessel and in the vicinity thereof. The aim is to prevent the molten metal from being solidified in the taphole and in the channels of the sliding gate mechanism. The gas can be an inert gas or a gas mixture, for example nitrogen or argon. The gas can also be a reactive gas, such as air, natural gas, propane, hydrogen, chloride, steam or carbon dioxide or a mixture of these, or a reactive gas diluted with an inert gas.

According to an embodiment of the invention, the porous part of the feed channel is defined by the housing of the adjusting plate and by the metal flow channel made in the adjusting plate, which makes it possible to feed gas into the metal flow channel of the adjusting plate during the flowing of the metal. According to another embodiment of the invention, the porous part of the gas feed channel is defined by the housing of the adjusting plate and surrounds the metal flow channel made in the adjusting plate, in which case gas can be fed into the metal flow channel made in the adjusting plate during the flowing of the metal. The various embodiments of the invention are described in more detail below, with reference to the appended drawings.

Figure 1 illustrates a sliding gate mechanism according to the invention, arranged in the taphole of a metallurgic furnace.

Figures 2 and 3 illustrate a sliding gate according to a preferred embodiment of the invention, viewed in a position where molten metal has free access to flow into the tapping pipe.

Figures 4 and 5 illustrate the sliding gate according to figures 2 and 3, viewed in a position where gas flows into the taphole.

Figures 6 and 7 illustrate the sliding gate according to figures 2 and 3, viewed in the off-position.

In figure 1 , in the taphole 13 of a metallurgic furnace 100 there is arranged a sliding gate mechanism 110 for tapping molten metal 102 from the furnace to the tapping channel 18. The taphole 13 is a channel arranged in the wall structure 101 of the furnace 100. The sliding gate mechanism 110 includes a counterpiece 14, fixed permanently in the furnace taphole 13 by means of an adjusting plate; said counterpiece is provided with a flow channel 15. From the furnace 100 illustrated in figure 1 , molten metal 102 can be discharged to the taphole 13, when the furnace 100 is suitably inclined. The flowing of the molten metal discharged from the flow channel 15 is adjusted by means of an adjusting plate 16 that is arranged to slide with respect to the counterpiece 14. In the adjusting plate 16, there is made a flow channel 17, through which molten metal has free access to flow into the tapping channel 18. The solid section of the adjusting plate 16 can be slid between the flow channel 15 and the tapping channel 18, so that that the flowing of metal to the tapping channel 18 is prevented. In the position illustrated in figure 1 , the sliding gate 110 allows the metal to flow into the tapping channel 18. The adjusting plate 16 is provided with a porous ceramic gas feed channel 112 for feeding gas to the flow channel 15 of the counterpiece 14. The gas feed channel 112 can be slid to cover the whole flow channel 15 of the counterpiece, in which case the gas flows into the flow channel 15. The pipe 19 of the tapping channel is permanently fitted in the adjusting plate 16. According to an embodiment of the invention, the pipe of the tapping channel is arranged in a stationary fashion with respect to the counterplate. In the embodiment according to figure 1 , the motion of the adjusting plate is arranged to be winding, but according to another embodiment of the invention, the motion of the adjusting plate is arranged to proceed in a linear fashion.

Figures 2 and 3 illustrate a sliding gate mechanism according to a preferred embodiment of the invention. Figure 3 illustrates a view of figure 2, seen along the section B - B. The counterpiece 24 is permanently fitted in the furnace wall structure 201 by means of an adjusting plate 230. The wall structure 201 includes the furnace taphole 23. The flow channel 25 of the counterpiece is arranged at the furnace taphole 23, so that the melt can flow unobstructed to the channels 23 and 25. By means of the adjusting plate 26, the flowing of metal from the channel 25 to the furnace tapping channel 28 is adjusted. The tapping channel 28 is attached to a fastening plate 214. The tapping channel 28 and the respective fastening plate 214 are arranged in a stationary fashion with respect to the counterpiece 24. According to another embodiment of the invention, the tapping channel 28 is permanently attached to the adjusting plate 26. The adjusting plate 26 is arranged to turn with respect to the gas feed aperture 213 and to slide against the counterpiece 24 and the fastening plate 214 of the tapping channel 28. The adjusting plate 26 is provided with a moving mechanism 203 for turning the adjusting plate with respect to the gas feed aperture 213 and for turning the adjusting plate 26 in various different functional positions. The feeding of gas to the flow channel 27 of the adjusting plate is arranged through the gas feed channel 212 of the adjusting plate 26. The gas feed channel 212 is made of porous ceramic material that on one side is bordered by the adjusting plate flow channel 27, so that gas can be fed into the flow channel 27 also when melt flows therein. The gas feed channel 212 is arranged to be bordered also by that surface of the adjusting plate 26 that is on the side of the counterpiece 24, in which case the gas is arranged to be fed to the flow channel 25 of the counterpiece when the gas feed channel 212 is turned in front of the channel 25. Gas is fed to the gas feed channel 212 from the side that is opposite to the surface bordered by the counterplate 24, and the gas feed aperture 213 leads the gas to said channel. Gas is fed along the pipe 231 to a hole of the adjusting plate 230, which hole opens into the gas feed aperture 213. The adjusting plate 26 includes two adjusting plate flow channels 27, 271 and two gas feed channels 212 and 272. This is an advantageous arrangement, because the flow channel 27 or 271 wears in use, and now it can be replaced by a new one simply by turning an unused pair of flow channel (27 or 271) and gas feed channel (212 or 272) to be employed in operation.

In an arrangement according to an embodiment of the invention, the feeding of gas to the porous channel of the adjusting plate is arranged through a gas feeding pipe arranged in the adjusting plate.

In an arrangement according to an embodiment of the invention, the porous part of the feed channel is defined by the housing of the adjusting plate and surrounds the metal flow channel of the adjusting plate, so that gas can be fed into the metal flow channel of the adjusting plate when the metal is flowing.

According to an embodiment of the invention, the counterplate is provided with at least two flow channels that can be turned separately to between the adjusting plate channel and the furnace taphole for controlling the flowing of metal, so that a worn flow channel can be replaced by an unused flow channel by changing the position of the counterplate.

In figures 4 and 5, the sliding gate mechanism described in figures 2 and 3 is in a position where gas is fed to the counterpiece flow channel 25, and to the furnace taphole 23 through the gas feed channel 212 or 272, in which case the gas flush keeps the molten metal in motion in the taphole and prevents it from being solidified.

In figures 6 and 7, the sliding gate mechanism of figures 2 and 3 is in a completely closed position, so that the solid part of the adjusting plate 26 is turned to block the flow channel 25 provided in the counterpiece.

100 metallurgic furnace 101 , 201 wall structure and lining of furnace 102 molten metal 110 sliding gate mechanism 13, 23 furnace taphole 14, 24 counterpiece 15, 25 flow channel of counterpiece 16, 26 adjusting plate 17, 27, 271 flow channel of adjusting plate 18, 28 tapping channel 19, 29 part/guide pipe bordering the tapping channel 112, 212, 272 gas feed channel 203 adjusting plate moving mechanism 213 gas feed aperture 214 fastening plate of guide pipe 230 mounting plate 231 gas feed pipe