JPS5989704A - Electromagnetic desulfurizer - Google Patents

Abstract

PURPOSE:To provide a titled device which stirs and heats a molten metal and desulfurizes effectively said metal by providing a vessel for molten metal consisting of a refractory material in a cylindrical induction coil, and communicating the lower part of the vessel and a charging port positioned at the same level as the upper part of the vessel. CONSTITUTION:An induction coil 1 formed by winding a water cooling pipe into a cylindrical shape is supported together with an iron core 5 by annular supports 2, 3, and a vessel 4a for molten metal consisting of a refractory material is provided in the coil 1. A communication pipe 4b of a refractory material which communicates the bottom of said vessel and a charging port 4c positioned at the same level as the vessel 4a is provided, whereby a furnace body 4 is constituted. The molten metal R supplied, via an inflow spout 6 for the molten metal, from a cupola, (not shown in figure), is added with a desulfurizing agent from an addition pipe 7 for the desulfurizing agent in the vessel 4a; at the same time, stirring flow is induced therein in an arrow direction by the coil 1 and the molten metal is heated, whereby the molten metal is effectively desulfurized. The desulfurized metal overflows from the port 4c into a casting mold (not shown in figure) according to the supply rate of the molten metal from the cupola.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electromagnetic desulfurization device that effectively obtains a desulfurization effect while preventing a drop in the temperature of a molten metal to be desulfurized.

Cupolas are widely used in iron foundries as a means of obtaining molten metal. Meanwhile, in order to obtain high quality cast iron,
It has been considered to add a spheroidizing agent to the molten metal before pouring it into a mold to obtain spheroidal graphite cast iron.

The production volume of this spheroidal graphite cast iron is increasing, but since the molten metal produced using the cupola contains a high concentration of sulfur derived from coke as a fuel, it is necessary to add a spheroidizing agent. The progress of graphite spheroidization is insufficient and it cannot be put to practical use.

For this reason, in the production of spheroidal graphite cast iron using molten metal produced in a cupola, it is common to provide a desulfurization step before adding the spheroidal additive. This desulfurization requires adding a desulfurizing agent to the molten metal and stirring to promote the reaction, and there are several methods available in the prior art. The first method is called the porous plug method, in which N2 gas that does not react with the molten metal is blown up from the bottom of the molten metal container through a porous plug installed at the bottom of the container, and the molten metal in the container is stirred by the upward force of the N2 gas bubbles. The second method is called the gas injection method, in which a refractory tube is immersed in the molten metal, and N2 gas is injected as a carrier gas together with powdered carbide through the tube to obtain stirring and reaction.

By the way, these two methods are considered problematic as they are the backbone of the actual desulfurization process. Typical examples of the porous plug method are as follows. In other words, [550°C at the time of tapping the Cubola → Temperature inside the porous plug desulfurization equipment 1450'C → 1400°C at the time of tapping after adding the desulfurizing agent.
'c→casting'.

However, if the product is a small or thin product, the casting temperature will be 1400°C to 1430'C.
Considering the temperature drop during transport to the mold after addition of the desulfurizing agent and during sequential casting into a plurality of molds, it can be seen that the above temperature conditions are not practical.

Because of this problem, when producing spheroidal graphite cast iron using a cubera as melting equipment (which is usually used in most cases from the point of view of cost), it is common to provide means for raising the temperature of the molten metal after desulfurization treatment. As a means for this purpose, there is a general tendency to use a channel induction furnace, but it is difficult to introduce it in relatively small-scale production plants because of its large expense ratio.

An object of the present invention is to provide an electromagnetic desulfurization apparatus equipped with electromagnetic means that has both stirring power and temperature raising ability for uniformly distributing the desulfurization agent.

The illustrated embodiment will be specifically described below. 1st
The figure is a sectional view of the desulfurization apparatus according to the present invention, and FIG. 2 is a plan view excluding the means for adding molten metal and desulfurization agent. In each figure, reference numeral 1 denotes an induction coil, which is formed by winding a water-cooled pipe into a cylindrical shape, and circular supports 2 and 3 arranged above and below the induction coil.
It is assumed that it is supported by bolts (not shown).

Reference numeral 4 denotes a furnace body, which is formed by hardening the furnace material, and forms a molten metal container 4a in the area surrounded by the coil.
a and the induction coil 1 constitute a so-called crucible-shaped induction furnace. Reference numeral 4b denotes a communicating pipe, which is formed, for example, from a pipe made of the same type of material as the molten metal to be treated, and is formed based on melting with the molten metal. This communication pipe 4b is connected to the container 4.
The bottom part of a is connected to the pouring spout 4c. Incidentally, the level of the melt coming out of the pouring port 4e is adjusted when the level of the molten metal supplied into the molten metal container 4a reaches the upper end of the induction coil 1. Reference numeral 5 denotes iron cores, which are arranged at appropriate intervals around the induction coil 1, facing vertically. A molten metal inlet trough 6 supplies the molten metal produced from a not-shown A cubera to the molten metal container 4a of the desulfurization apparatus. Reference numeral 7 denotes a desulfurizing agent addition pipe, which cuts out an appropriate amount of desulfurizing agent into the molten metal container according to the amount of molten metal R supplied to the molten metal container 4a per unit time.

In the above configuration, first, the molten metal R obtained from the cubera (not shown) is poured into the molten metal container 4a formed in the furnace body 4 through the molten metal inlet trough 6, and the molten metal level gradually rises. Ku. Simultaneously with the rise in the molten metal level in the container 4a, the continuous rise in the molten metal level stops, and an equal amount of molten metal flowing from the molten metal inflow gutter is supplied to a mold (not shown) from the pouring port 4C.

On the other hand, the molten metal flowing into the molten metal container 4a from the molten metal inlet trough 6 is poured into the container 4a, and a desulfurizing agent is added from the desulfurizing agent addition pipe 7, thereby alternating the desulfurization action.

To explain the operation in more detail, first, a single-phase AC voltage of 111 jJD is applied to the induction coil 1. As a result, an alternating magnetic flux is generated surrounding the vertical cross section of each part of the induction coil 1. This magnetic flux passes through the molten metal R accumulated in the container 4a, and an eddy current is generated by the magnetic flux passing through the molten metal. This eddy current not only compensates for the temperature drop within the container, but also serves to raise the temperature. Simultaneously with this temperature raising action, a current flows in the molten metal in a bundle in the opposite direction to the current flowing through the induction coil 1 due to the magnetic flux passing through the molten metal container 4A. Since these bundled currents are in the same direction, a repulsive force is generated in the molten metal R, which causes the molten metal R to move from the periphery to the center, and when the phase of the voltage supplied to the induction coil l is reversed, the current The reversal of the flow direction has a constricting effect, which promotes uniform distribution of the added desulfurizing agent and promotes the desulfurizing action. The molten metal that has completed the desulfurization action in this manner continuously flows out from the pouring port 4C. When the magnetic flux surrounding the induction coil 1 is placed outside), it concentrates on the iron core 5 and prevents induction heating of the T-frame (made of iron), not shown. does not require

The humidity of the molten metal in the apparatus of the present invention may change as follows. That is, "550° C. at the time of tapping the Cubola - Temperature in the sulfurizing device 1500'c -> Fullness at the time of tapping after desulfurization 1450' (: → Casting").

In other words, it can be seen that the temperature inside the desulfurization apparatus is normally substantially increased by 50° compared to the above-mentioned humidity condition.In addition, in order to clarify the specific concept of the electromagnetic desulfurization apparatus according to the present invention, To show the specifications using a typical example, Cubola... 2 on/Hr when hot water is tapped & M
degree 1550-C main desulfurization equipment...molten metal amount 400
kq coil power: 100 KW Molten metal residence time: 400/2000 x 60 = 12 minutes Humidity heating power: approximately 50'C.

In addition, in the above explanation, by the time the molten metal level in the desulfurization equipment rises, the amount of molten metal already in the communication pipe is very small compared to the amount of molten metal that has already entered the communication pipe. The molten metal may be discarded. Further, although the connection position of the communication pipe 4b from the container 4a, which performs heating and stirring functions, is at the bottom of the container 4a, it may be connected to the lower side of the container 4a due to the shape of the furnace body 4. However, in this case, a part of the lower part of the induction coil 1 is bent downward, and the coil 1
It may also be necessary to connect communication pipes from the sides. On the other hand, part or all of the communication tube may be placed inside the induction coil 1. Further, the guide filter 1 is not limited to a cylindrical shape, and may be any shape as long as it is cylindrical.

As described above, the electromagnetic desulfurization apparatus according to the present invention includes a cylindrical induction filter and a molten metal container formed of a refractory material inside the cylindrical induction filter, and a fireproof molten metal container that communicates with an external pouring port from the lower part of the container. The external pouring port is located at the same level as the upper part of the container, and the molten cast iron and desulfurization agent are simultaneously received as a continuous flow from the molten metal container, and the desulfurized metal overflows from the communication path. It is configured to obtain molten metal. Based on this configuration, it is possible to effectively combine both the stirring power and the temperature raising power generated by electromagnetic induction with the desulfurization effect, and in particular, it is possible to eliminate the adverse effects associated with the temperature drop in the desulfurization equipment without installing a separate temperature raising device. The practical benefit of removing it is huge. Furthermore, the same amount of molten metal introduced into the desulfurization device is obtained regardless of the size of the hole in the communication pipe, and the amount of molten metal discharged is controlled by controlling the amount of molten metal discharged from the cubera. Furthermore, since the difference in head between the receiving hot water and the hot water coming out is small,
It can be simply introduced into existing factory processes.

[Brief explanation of drawings]

FIG. 1 is a sectional view, and FIG. 2 is a partially omitted plan view. 1...Induction fill 4...
... Furnace body 4EL ... Molten metal container 4b ...
...Communication pipe 4c...Pouring port 6...
...Molten metal inflow gutter 7 ...Desulfurizing agent addition pipe Applicant Shinko Electric Co., Ltd. Agent Patent attorney Haruya Saito

Claims (1)

[Claims] 1. A molten metal container is formed using fireproof insulation in a space surrounded by a cylindrical induction coil, and a molten metal pouring port is provided at an appropriate location outside the induction coil at a level corresponding to the upper end of the induction coil in the molten metal container, and An electromagnetic desulfurization apparatus characterized in that a communication pipe connected from a lower part of the molten metal container to the pouring port is provided, and means for supplying molten metal to be desulfurized and a deflow agent to the molten metal container are provided.