JP2010270963A - Electric smelting furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric smelting furnace for melting and reducing oxide material, capable of efficiently obtaining desired molten metal while minimizing generation of flame spewing phenomenon, even when the material composed of oxide having high ZnO content is melted and reduced. <P>SOLUTION: This electric smelting furnace 10 includes a furnace body 12, a furnace cover 14, a material charging pipe 16 fitted and inserted to a material inlet 14a formed on the furnace cover 14 at its downstream end, an electrode 18 disposed in a state of vertically penetrating through the furnace cover 14, and a grate damper 42 disposed on an intermediate section of the material charging pipe 16, wherein a shelf sweeping device 20 for striking shelf t of the oxide material formed in the furnace body 12, by moving a striking shaft 48 forward and backward from an exhaust gas outlet 14c into the furnace body 12, is disposed at the exhaust gas outlet 14c formed on the furnace cover 14, and the grate damper 42 is provided with a grate damper remote control device 22 for remote-controlling an opening of the grate damper 42. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electric smelting furnace used for melting and reducing steel by-products.

  In recent years, from the viewpoint of saving resources, steelmaking dust generated in the steelmaking process, scale generated in the annealing process, waste acid sludge generated in the pickling process, etc. are used as raw materials (oxide raw materials), and this is made into a briquette shape. It is practiced to recover a valuable metal such as Ni, Cr, Fe, Mn by melting and reducing a molded material (hereinafter, also simply referred to as “briquette”) in an electric smelting furnace (for example, Patent Document 1). reference).

  FIG. 3 is a schematic view showing a conventional electric smelting furnace 1 used for recovering such valuable metals. As shown in this figure, the electric smelting furnace 1 is generally composed of a furnace body 3, a furnace lid 4, a throwing pipe 5 and an electrode 7.

  The furnace body 3 is an upper opening container to which the briquette m that is to be heated is supplied and melted, and the furnace lid 4 that seals the upper opening of the furnace body 3 is charged with raw materials such as the briquette m. The downstream end of the projecting pipe 5 is inserted. In addition, the furnace body 3 is attached with a plurality of electrodes 7 made of graphite that penetrates the furnace lid 4, the tip of the furnace body 3 is disposed in the furnace body 3, and is supported to be moved up and down by an electrode lifting device 9. ing. By supplying electric power to the electrode 7, current flows through the briquette m through the electrode 7 in the furnace body 3, and Joule heat is generated, and the briquette m is heated and melted.

  When recovering valuable metals from raw material briquettes m made of oxides such as steelmaking dust, scale and waste acid sludge using this electric smelting furnace 1, carbonaceous materials and generation After blending an adjusting material (for example, lime) for adjusting the fluidity of the slag, these are put into the furnace body 3 and heated. Then, the oxide raw material constituting the briquette m is melted and reduced by C (carbon) contained in the briquette m or added as a carbonaceous material, and separated into a metal component and a slag component, Ni, Cr, Fe, Valuable metals such as Mn are recovered.

JP 2008-240138 A

  In the conventional electric smelting furnace 1, the inside of the throwing pipe 5 fitted into the furnace lid 4 is always filled with the raw material. That is, the in-furnace raw material layer extends to the lower end of the thrown pipe 5, and the raw material is always replenished through the thrown pipe 5 from the raw material hopper H on the furnace by the amount that the raw material is melted by electric heating and the volume is reduced. It has a structure. Therefore, the thickness of the in-furnace raw material layer depends on the insertion length of the thrown pipe 5 into the furnace and cannot be changed according to the in-furnace situation.

  By the way, when the raw material briquette m made of oxide is melted and reduced, a bumping phenomenon of the molten metal S occurs at a certain frequency. In particular, when the content of ZnO (zinc oxide) in the briquette m is large, the flame ejection phenomenon is likely to occur by the following mechanism.

  That is, ZnO in briquette m becomes Zn when it is reduced with C, and evaporates at about 900 ° C. Then, the evaporated Zn is oxidized again by oxygen in the air in the furnace body 3 to become ZnO, and is attached to the briquette m present in the upper part of the furnace body 3 and solidifies.

  Here, in the vicinity of the exhaust gas outlet 4a opened on the ceiling portion of the furnace lid 4, ZnO re-oxidized by oxygen in the air taken from the surrounding secondary air intake (not shown) becomes briquette m. When adhering and solidifying, adjacent briquettes m are joined together to form a shelf t in the raw material layer.

  When the shelf t made of briquette m and ZnO grows to a certain size and cannot withstand its own weight and falls into the molten metal S, CO (carbon monoxide) is generated by a rapid reduction reaction by C. At the same time, the residual moisture of the briquette m is abruptly vaporized, causing a small explosion in the molten metal S, and a flame is ejected from the secondary air intake port.

  When such a flame ejection phenomenon occurs, the working environment around the electric smelting furnace 1 is exposed to danger, and the furnace body 3 and the furnace lid 4 are damaged, and the recovered valuable metal There has also been a problem that the mixing ratio and the yield are changed.

  Here, in the conventional electric smelting furnace 1, if the insertion length of the thrown pipe 5 inserted in the furnace body 3 is short, the raw material layer in the furnace becomes thick, resulting in a temperature difference between the upper and lower sides of the raw material layer. Becomes larger and the shelf t is likely to grow. On the other hand, in order to suppress the growth of the shelf t, it is only necessary to lengthen the insertion length of the thrown pipe 5, but as a result, the raw material layer in the furnace becomes thin, resulting in a high temperature up to the upper surface of the raw material layer and a large energy loss. In addition, the tip of the thrown pipe 5 is exposed to a high temperature, and the life of the thrown pipe 5 is significantly shortened. Therefore, as the best mode of operation, when the shelf t grows, the furnace raw material layer is thinned to suppress the growth of the shelf t, and when the operation is stable, the furnace raw material layer is thickened to reduce the energy loss. Although it is desirable to suppress the load on the refractory and the conventional electric smelting furnace 1, the thickness of the raw material layer in the furnace cannot be changed during such operation.

  It should be noted that when the supply of the raw material into the furnace main body 3 is stopped for maintenance, or conversely, when the supply is started, the loss damper 5a (see FIG. 3) provided at the intermediate portion of the throwing pipe 5 The operator can manually open and close. However, it is dangerous and a safety problem to operate the rooster damper 5a in order to control the raw material supply amount during operation and suppress the flame blowing phenomenon. Therefore, conventionally, as a method for avoiding the above-mentioned flame ejection phenomenon, for example, measures such as limiting the ZnO content in the raw material have been taken, but this method increases the cost because of the pretreatment of the input raw material. There was a problem of becoming.

  Therefore, the main problem of the present invention is to obtain a desired molten metal safely and efficiently by minimizing the occurrence of a flame ejection phenomenon even when a raw material made of an oxide having a high ZnO content is melted and reduced. It is to provide an electric smelting furnace for melting / reducing oxide raw materials.

The invention described in claim 1
(A) A furnace main body 12 for melting the oxide raw material inside, a furnace lid 14 provided so as to close the upper portion of the furnace main body 12, and a raw material inlet 14a having a downstream end opened in the furnace lid 14 The electric smelting furnace 10 is provided with an injection pipe 16 that is inserted into the furnace body 12 and introduces an oxide raw material into the furnace body 12 and an electrode 18 that penetrates the furnace lid 14 in the vertical direction. And
(B) A striking shaft 48 advances and retreats from the exhaust gas outlet 14 c into the furnace body 12 at the exhaust gas outlet 14 c opened in the furnace lid 14, and the oxide raw material formed in the furnace body 12 A shelf dropping device 20 for hitting the shelf t is provided.

  In the present invention, the shelf dropping device 20 in which the striking shaft 48 advances and retreats from the exhaust gas outlet 14 c into the furnace body 12 is provided in the vicinity of the exhaust gas outlet 14 c opened in the furnace lid 14. When a large amount of oxide raw material is melted and reduced, the oxide raw material shelf t (see FIG. 3) formed in the vicinity of the exhaust gas outlet 14c falls into the molten metal S under its own weight, and causes a flame ejection phenomenon. Prior to growth, the shelf t can be knocked down into the molten metal S and melted safely.

The invention described in claim 2 is the electric smelting furnace 10 according to claim 1,
(C) A rooster damper 42 is provided at an intermediate portion of the throwing pipe 16, and
(D) In the rooster damper 42, the inside of the furnace main body 12 is controlled so as to suppress the growth of the oxide raw material shelf t formed in the furnace main body 12 by remotely controlling the opening and closing of the rooster damper 42. A roster damper remote control device 22 for freely controlling the amount of the oxide raw material charged into is attached.

  In the present invention, since the rooster damper remote control device 22 for remotely controlling the opening and closing of the rooster damper 42 is attached to the rooster damper 42 provided in the middle part of the throwing pipe 16, the rooster damper 42 is operated during operation. It is possible to control the thickness of the in-furnace raw material layer freely by controlling the supply amount of the oxide raw material charged into the furnace body 12 by remotely operating the opening and closing. By controlling the thickness of the in-furnace raw material layer in this way, the temperature of the raw material layer can be set to a temperature at which it is difficult for the shelf t to be generated, and the growth of the shelf t can be suppressed. However, the rooster damper 42 can be remotely closed and the oxide raw material charged into the furnace body 12 can be narrowed to suppress the flame ejection phenomenon. By providing such a remote control device 22 for the rooster damper, it is not necessary for the operator to go to the rooster damper 42 on the furnace and manually operate the damper 42. Even in such a case, the rooster damper 42 can be operated extremely safely.

  According to the present invention, the flame blowing phenomenon of the electric smelting furnace can be minimized, so that the working environment around the electric smelting furnace is exposed to danger and the furnace body is effectively damaged. While being able to suppress, it can reduce that a change arises in the mixture ratio and yield of the valuable metal collect | recovered in a molten metal.

  Therefore, even when a raw material made of an oxide having a high ZnO content is melted and reduced, it is possible to melt and reduce the oxide raw material that can safely and efficiently obtain a desired molten metal by minimizing the occurrence of the flame ejection phenomenon. An electric smelting furnace for reduction can be provided.

It is a block diagram which shows the outline | summary of the electric smelting furnace of one Example of this invention. It is a perspective view which shows an example of a shelf dropping device. It is a block diagram which shows the outline | summary of the conventional electric smelting furnace.

  Hereinafter, the present invention will be described in detail according to illustrated embodiments. FIG. 1 is a configuration diagram showing an outline of an electric smelting furnace 10 according to an embodiment of the present invention. As shown in this figure, the electric smelting furnace 10 of the present embodiment is roughly composed of a furnace body 12, a furnace lid 14, a throwing pipe 16 (and a rooster damper 42 attached thereto), an electrode 18, and a shelf dropping device 20. And the rooster damper remote control device 22.

  The furnace body 12 is an upper opening container that is made of a refractory material 24 such as a carbon stamp and obtains a molten metal S by melting an oxide raw material therein. On the side wall of the bottom of the furnace body 12, there is provided a tapping path 12a through which the molten melt S of the oxide raw material melted in the furnace body 12 passes, and the outer surface of the side wall of the tapping path 12a. A tap opening / closing device 25 that opens and closes the tap opening 12b is attached to the opening on the side, that is, the tap opening 12b. A tap mouth dust collector 26 for removing dust generated when the molten metal S is discharged from the tap mouth 12b is attached above the tap mouth 12b. The tap mouth dust collector 26 is provided with a damper 28 via a damper 28. A cyclone dust collector and a harmful gas removing device (not shown) are connected. Further, an air cooling jacket 12 c is attached to the outer surface of the furnace bottom of the furnace body 12, and the furnace bottom is cooled by the air supplied from the air cooling fan F. The upper portion of the furnace body 12 is sealed with a furnace lid 14.

  In addition, the codes | symbols 30a and 30b in FIG. 1 are the taps which guide the molten metal S taken out from the tap port 12b, the code | symbol 32 is a ladle, and the code | symbol 34 is a slag receptacle. Reference numeral 36 a is a thermocouple that measures the temperature of the furnace bottom of the furnace body 12, and reference numeral 36 b is a thermocouple that measures the temperature of the side wall of the furnace body 12.

  The furnace lid 14 is a lid formed by covering the inside of the outer skin 14a formed of a metal such as stainless steel with a refractory 38 such as an alumina refractory.

  One or a plurality of raw material charging holes 14a are formed in a substantially central portion of the furnace lid 14, and a downstream end of a projecting pipe 16 described later is fitted into each of the raw material charging holes 14a. In addition, one or a plurality of electrode insertion holes 14b through which electrodes 18 to be described later are inserted are formed at positions in the vicinity of the raw material introduction holes 14a in a substantially central portion of the furnace lid 14. Further, one or a plurality of exhaust gas outlets 14c and an inspection / secondary air intake port (not shown) are opened on the outer periphery of the furnace lid 14, and the exhaust gas outlet 14c includes a flange or the like. The T pipe joint 40 is attached via the attaching means. In addition, the code | symbol 36c in FIG. 1 is a thermocouple which measures the temperature of the interior space upper part of the furnace main body 12 with which the furnace cover 14 was attached.

  One or a plurality of raw material hoppers H that store oxide raw materials such as briquettes m that are adjusted in advance so that the blending ratio of the valuable metals becomes a predetermined one are provided above the furnace lid 14 attached to the furnace body 12. is set up. Each raw material hopper H is attached with a load cell 41 for detecting a change in the weight of the oxide raw material stored in the raw material hopper H. A detection signal of the change in the weight in the raw material hopper H detected by the load cell 41 is as follows: The signal is supplied to the control means 64 (described later) via a signal line (not shown).

  The throwing pipe 16 is a pipe for guiding an oxide raw material such as briquette m stored in the raw material hopper H into the furnace main body 12, and its downstream end is provided in the furnace lid 14 as described above. The material is inserted into the material charging hole 14a.

  A plurality of shafts (not shown) installed so as to cross the inside of the throwing pipe 16 are taken in and out of the middle part of the throwing pipe 16 so that the inside of the throwing pipe 16 is passed through the furnace body 12. A rooster damper 42 is attached to control the amount of the raw material metal to be introduced into the.

  The electrode 18 is mainly composed of graphite, and generates high-temperature Joule heat in the oxide raw material by the supplied power in order to heat and melt the oxide raw material charged into the furnace body 12. The electrode 18 is supported by an electrode elevating device 42 so as to be movable up and down, and its tip is inserted into an electrode insertion hole 14 b provided in the furnace lid 14 and arranged in the furnace body 12.

  Here, when three-phase alternating current is used as the power supplied to the electrode 18, three electrodes 18 are provided. On the other hand, when a DC power is used, one or a plurality of the electrodes 18 are provided, and a bottom electrode (not shown) is provided on the furnace bottom of the furnace body 12.

  The shelf dropping device 20 is a device for striking and dropping the oxide raw material shelf generated in the vicinity of the exhaust gas outlet 14c into the molten metal S when the oxide raw material having a high ZnO content is melted and reduced, as shown in FIG. In general, it includes a support frame 44, a guide rail 46, a striking shaft 48, a driving device 50, and the like.

  The support frame 44 is suspended from a ceiling surface or a rack near the furnace lid 14 and supports the guide rail 46, and one end of a guide rail connecting member 52 to which the guide rail 46 is connected is provided at the lower end thereof. Is attached to be swingable.

  The guide rail 46 is a rail member having a substantially H-shaped horizontal section that guides the striking shaft 48 in its forward / backward direction, and the back side (front side in FIG. 2) of one end in the longitudinal direction (lower end in FIG. 2) is connected to the guide rail. The other end of the member 52 is pivotally attached. A striking shaft 48 is inserted into the front side (the back side in FIG. 2) of one end of the guide rail 46 in the longitudinal direction, and a guide cell 54 for guiding the striking shaft 48 is attached and attached. A driving device 50 is attached to the other end in the longitudinal direction (the upper end in FIG. 2). The intermediate connecting portion 56 provided at the back intermediate portion of the guide rail 46 and the guide rail connecting member 52 are linked by the guide cell left and right cylinders 58, whereby the guide rail 46 (more specifically, the striking shaft 48). Of the guide rail connecting portion 52 can be swung by 10 ° to the left and right.

  The striking shaft 48 is a rod-shaped member made of a metal material such as stainless steel, and the lower end side thereof is inserted into the guide cell 54 and the upper end side thereof is connected to the guide rail 46 via an air breaker 60 of the driving device 50 described later. It is attached to the front side.

  The driving device 50 is a device that drives the striking shaft 48 to advance and retreat along the guide rail 46. The driving device 50 is attached to the front side of the guide rail 46 so as to be movable along the guide rail 46, and the upper end of the striking shaft 48 is connected. At the same time, the air breaker 60 that applies a striking force to the striking shaft 48 and the air breaker 60 that has moved to the lower end side of the guide rail 46 together with the striking shaft 48 are moved to the upper end side of the guide rail 46 that is the home position by a chain feed (not shown). And an air feed motor 62 for lifting.

  As shown in FIG. 1, the shelf dropping device 20 configured as described above is disposed in the vicinity of the exhaust gas outlet 14 c of the furnace lid 14, and the striking shaft 48 extends the exhaust gas outlet 14 c from the upper opening 40 a of the T fitting 40. It is installed to pass through and enter the furnace body 12. The side opening 40b of the T pipe joint 40 is connected to an exhaust gas passage (not shown).

  The rooster damper remote control device 22 is for remotely operating the rooster damper 42 provided in the middle part of the projecting pipe 16, and has an air cylinder 22a for opening and closing the rooster damper 42. A predetermined control signal or the like is given to the air cylinder 22a from the control means 64 installed remotely via the signal line L1 or the like, and the air cylinder 22a performs a predetermined operation by the signal or the like. The damper 42 is opened and closed.

  It should be noted that a predetermined control signal or the like is given to the control means 64 also to the shelf dropping device 20 via the signal line L2 or the like. That is, the shelf dropping device 20 can be remotely operated by the control means 64 in the same manner as the rooster damper 42.

  Next, the operation of the electric smelting furnace 10 configured as described above will be described. When recovering valuable metals by melting and reducing oxide raw materials composed of oxides such as steelmaking dust, scale and waste acid sludge using the electric smelting furnace 10, first, the oxide raw materials are not shown in the briquette. The material is put into a manufacturing apparatus, and the raw material briquette m is granulated. The briquette m is mixed with an adjustment material that adjusts the fluidity of the carbonaceous material and the generated slag as necessary, and then these are put into the furnace body 12.

  Subsequently, electric power is applied to the electrode 18 to generate Joule heat, and the briquette m is heated. By heating the interior of the furnace body 12 to a high temperature of about 1500 ° C., the oxide raw material constituting the briquette m is melted and reduced by C (carbon) contained in the briquette m or added as a carbon material. Minor and slag are separated, and valuable metals such as Ni, Cr, Fe, Mn are recovered.

  Here, in the electric smelting furnace 10 of the present embodiment, the shelf dropping device 20 in which the striking shaft 48 advances and retreats from the exhaust gas outlet 14 c into the furnace body 12 in the vicinity of the exhaust gas outlet 14 c opened in the furnace lid 14. Therefore, when the oxide raw material having a high ZnO content is melted and reduced, the oxide raw material shelf t formed in the vicinity of the exhaust gas outlet 14c serving as the cold air inlet falls into the molten metal S under its own weight. Thus, the shelf t can be knocked into the molten metal S and melted safely before it grows to a size that causes a flame ejection phenomenon.

  Moreover, the load cell 41 is installed in the raw material hopper H on a furnace, and the weight change of the raw material in this raw material hopper H can be detected. And since the rooster damper remote control device 22 which remotely controls the opening and closing of the rooster damper 42 is attached to the rooster damper 42 provided in the middle part of the throwing pipe 16, the weight of the oxide raw material in the raw material hopper H The thickness of the in-furnace raw material layer can be freely controlled by remotely operating the rooster damper 42 while viewing. By controlling the thickness of the raw material layer in the furnace in this way, the temperature of the raw material layer is set to a temperature at which the shelf t is difficult to generate, and the growth of the shelf t is suppressed. By closing the damper 42 from a remote location, the oxide raw material charged into the furnace body 12 can be throttled to suppress the flame ejection phenomenon.

DESCRIPTION OF SYMBOLS 10 ... Electric smelting furnace 12 ... Furnace main body 14 ... Furnace cover 16 ... Throwing pipe 18 ... Electrode 20 ... Shelf dropping device 22 ... Rooster damper remote control device 22a ... Air cylinder 42 ... Rooster damper 44 ... Support frame 46 ... Guide rail 48 ... Blow shaft 50 ... Drive device m ... Briquette S ... Molten metal

Claims (2)

A furnace main body for melting the oxide raw material therein, a furnace lid provided so as to close the upper portion of the furnace main body, and a downstream end fitted into a raw material charging port opened in the furnace lid, the furnace main body An electric smelting furnace comprising an injection pipe for introducing an oxide raw material therein, and an electrode disposed through the furnace lid in the vertical direction,
The exhaust gas outlet established in the furnace lid is provided with a shelf dropping device for striking a shelf of oxide raw material formed in the furnace body by moving a striking shaft forward and backward toward the furnace body. Electric smelting furnace. A roster damper is provided in the middle part of the throwing pipe,
The rooster damper is remotely controlled to open and close the rooster damper, and the oxide raw material charged into the furnace body so as to suppress the growth of the oxide raw material shelf formed in the furnace body. The electric smelting furnace according to claim 1, further comprising a remote control device for rooster damper that freely controls the amount of the smelter.