JP6350189B2 - Slag adhesion suppression method for tilting slag supply device - Google Patents

Description

  The present invention relates to a method for suppressing slag from solidifying and adhering to a bottom surface of a tilting slag supply device.

  Steelmaking slag generated in large quantities in the steelmaking process contains metal components such as Fe and Mn, and P, etc., but due to expansion and collapse due to containing a large amount of CaO, roadbed materials and aggregates The use to etc. was restricted. However, in recent years, recycling of resources has been actively promoted, and many methods for recovering valuable materials from steelmaking slag have been proposed so far (see Patent Documents 1 to 9 and Non-Patent Document 1).

  However, the conventional method for recovering valuable materials is low in processing efficiency because the steelmaking slag in a molten state is processed every predetermined amount (that is, batch processing), and a plurality of steps are required until a recycling resource is obtained. In the end, there is a problem that the recycling cost increases.

  Therefore, a reduction treatment method has been proposed in which molten steelmaking slag is directly charged into a reduction furnace for treatment (see Patent Documents 10 to 12).

  For example, Patent Document 10 proposes a reduction treatment method in which slag is continuously charged from a slag pot into an opening of a reduction furnace. However, in this reduction treatment method, a solidified slag layer is formed on the slag surface and the bottom of the slag pan, and the amount of slag that can be treated is significantly reduced.

  In the reduction treatment methods of Patent Documents 11 and 12, solidification of the slag surface in the slag supply container can be prevented, but slag adheres to the bottom surface of the slag supply container and gradually accumulates. If slag adheres and accumulates on the bottom surface of the slag supply container, the amount of slag contained in the container decreases, and the slag reduction treatment efficiency naturally decreases because it is necessary to remove the attached and accumulated slag.

Japanese Patent Laid-Open No. 52-033897 JP-A-53-054196 Japanese Patent Laid-Open No. 55-10092 Japanese Unexamined Patent Publication No. 07-223857 Japanese Patent Application Laid-Open No. 08-198647 Special table 2003-520899 gazette JP 2004-331449 A JP 2009-132544 A Australian Patent AU-B-20553 / 95 Specification JP 2006-528732 A Japanese Patent No. 5522320 Japanese Patent No. 5541423

Scandinavian Journal of Metallurgy 2003; 32: p.7-14

  As described above, the reduction treatment method in which molten steelmaking slag is directly charged into the reduction furnace and processed, the slag solidifies and deposits on the bottom surface of the slag supply device that supplies the steelmaking slag to the reduction furnace. The problem is that the reduction efficiency is reduced.

  That is, when the slag supply device is tilted continuously or intermittently and the molten steelmaking slag is directly charged into the reduction furnace, the steelmaking slag solidifies and deposits on the bottom surface of the slag supply device, and the slag supply In some cases, the total weight of the device increases to reach the limit weight, or the slag capacity of the device decreases to reach the limit capacity and the slag supply device must be replaced.

  Naturally, the replacement of the slag supply device significantly reduces the operating rate of the reduction furnace, so it is necessary to reduce the frequency of replacement of the slag supply device, or to avoid the replacement of the slag supply device as much as possible. .

  Therefore, the present invention suppresses an increase in the solidification adhesion amount of the slag or reduces the solidification adhesion amount of the slag on the bottom surface of the tilting slag supply device, thereby reducing the molten slag to the reduction furnace (hereinafter referred to as the slag solidification adhesion amount). In particular, there is a need to stabilize the direct charging of molten steelmaking slag and to ensure stable operation of the reduction furnace, and to provide a slag adhesion suppression method that solves this problem The purpose is to do.

  The inventor has intensively studied a method for solving the above problems. As a result, when the tilting slag supply device is empty, the molten metal is charged into the device, and the slag solidified and adhered to the bottom surface of the tilting slag supply device with the heat of the hot metal (hereinafter referred to as “adhesion slag”) It was found that the increase in the amount of adhered slag on the bottom surface of the tilting slag supply device can be suppressed as much as possible by melting the surface layer of the slag supply device and letting it flow into the reduction furnace together with the hot metal.

  This invention was made | formed based on the said knowledge, and the summary is as follows.

(1) In a tilting slag supply device that also serves as an exhaust gas path for a reduction furnace, in a reduction treatment in which molten slag is continuously or intermittently charged into the reduction furnace and the slag is reduced, the tilting slag supply device A method of suppressing an increase in the amount of slag that solidifies and adheres to the bottom surface,
The tilting slag supply device is required until the molten slag in the tilting slag supply device has been charged into the reduction furnace and then the new molten slag is charged into the tilting slag supply device. Tilt-type slag, characterized in that it is held at an inclination angle of, and hot metal having a temperature exceeding the melting point of the slag is charged, and the hot metal is directly charged into a reduction furnace through a tilt-type slag supply device. A method for suppressing slag adhesion of a supply device.

  (2) The tilting slag supply according to (1), wherein the tilt angle is an angle formed by a bottom surface of the tilting slag supply device and a horizontal plane, and is an angle of 10 ° or more above the horizontal plane. A method of suppressing slag adhesion of a device.

(3) In a tilting slag supply device that also serves as an exhaust gas path for a reduction furnace, in a reduction process in which molten slag is continuously or intermittently charged into the reduction furnace and the slag is reduced, the tilting slag supply device A method of suppressing an increase in the amount of slag that solidifies and adheres to the bottom surface,
In the tilting slag supply device, the molten slag in the tilting slag supply device has been charged into the reduction furnace, and then the new molten slag is charged into the tilting slag supply device. A method for suppressing slag adhesion in a tilting slag supply device, wherein hot metal having a temperature exceeding the melting point of the slag is charged, and the tilting slag supply device is swung at a swing angle in a range in which the hot metal does not flow out to the reduction furnace. .

  (4) The tilting type according to (3), wherein the peristaltic angle is an angle between a bottom surface of the tilting slag supply device and a horizontal plane, and is an angle of 15 ° to 10 ° below the horizontal plane. Slag adhesion suppression method of slag supply device.

  (5) The temperature of the hot metal is 1400 ° C. or more, The method for suppressing slag adhesion of the tilting slag supply device according to any one of (1) to (4).

  (6) The adhesion slag suppression method for a tilting slag supply device according to any one of (1) to (5), wherein the molten slag is a molten steelmaking slag.

  According to the present invention, even the adhered slag having a low thermal conductivity is melted and discharged to the reduction furnace, and the increase in the amount of adhered slag on the bottom surface of the tilting slag supply device is suppressed or the amount of adhered slag is reduced. Therefore, direct charging of the molten slag into the reduction furnace can be stabilized, and stable operation of the reduction furnace can be ensured.

It is a figure which shows the aspect which suppresses the growth of the adhesion slag of the bottom part surface of a tilting-type slag supply apparatus. It is a figure which shows the relationship between the frequency | count of charging of molten slag, the charging amount and adhesion amount of molten slag. It is a figure which shows another aspect which suppresses the growth of the adhesion slag of the bottom part surface of a tilting-type slag supply apparatus.

The method for suppressing slag adhesion of a tilting slag supply device according to the present invention (hereinafter sometimes referred to as “the method of the present invention”) is a tilting slag supply device that also serves as an exhaust gas path of a reduction furnace. In the reduction process of intermittently charging into a reduction furnace and reducing the slag, it is a method of suppressing an increase in the amount of slag that solidifies and adheres to the bottom surface of the tilting slag supply device,
After the molten slag in the tilting slag supply device has been charged into the reduction furnace, the tilting slag supply device is required until the new molten slag is charged into the tilting slag supply device. The hot metal having a temperature exceeding the melting point of the slag is charged while being held at an inclination angle, and the hot metal is charged as it is into the reduction furnace through the tilting slag supply device.

Further, the method of the present invention is a tilting slag supply device that also serves as an exhaust gas path of a reduction furnace, and in a reduction process in which molten slag is continuously or intermittently charged into the reduction furnace and the slag is reduced, the tilting type A method of suppressing an increase in the amount of slag that solidifies and adheres to the bottom surface of the slag supply device,
After the molten slag in the tilting slag supply device has been charged into the reduction furnace, the slug type slag supply device is charged with the slag until the new molten slag is charged into the tilting slag supply device. The hot metal having a temperature exceeding the melting point is charged, and the tilting slag supply device is rocked at a rocking angle in a range in which the hot metal does not flow out to the reduction furnace.

  The method of the present invention will be described below with reference to the drawings.

  In FIG. 1, the aspect which suppresses the growth of the adhesion slag of the bottom part surface of a tilting-type slag supply apparatus is shown.

  The reduction furnace 1 includes a furnace bottom 1d, side walls 1a and 1b, and an upper lid 1c. The reduction furnace 1 includes an electrode 2 that passes through the upper lid 1c. It has an inlet 3 for molten slag supplied by a tilting slag supply device 7 arranged integrally. The reduction furnace 1 is usually a DC type or AC type fixed electric furnace having a sealed structure, and contains a molten metal 5 having a temperature of about 1450 ° C. and a molten slag 6 subjected to a reduction treatment of about 1550 ° C. on the molten metal 5. ing.

  The side wall 1a or 1b of the reduction furnace 1 is provided with a tap hole (not shown) for discharging the molten slag 6 and a tap hole (not shown) for discharging the hot metal 5.

  At the charging port 3, the tilting slag supply device 7, which is integrally connected to the reduction furnace 1 via the charging pipe 4 and is a discharge path for the exhaust gas of the reduction furnace 1, has a slag pan (not shown). The molten slag to be supplied is temporarily stored / held, and then the flow rate is controlled in the reduction furnace 1 through the inlet 4 and continuously or intermittently on the molten slag 6 layer on the hot metal 5. And it is a device that pours statically.

  The tilting slag supply device 7 is composed of a bottom portion 9, an upper portion 9 b, and a side portion 8 made of a water-cooled refractory wall. An opening 8 a through which molten slag flows out on a surface facing the side portion 8, and melting An inlet pipe 4 for introducing slag to the charging port 3 is provided, and an exhaust port 13 for exhausting the gas in the tilting slag supply device 7 is provided in the upper portion 9b, and a slag pan (not shown) is an inlet 14 for introducing molten slag (input) The lid for closing the mouth is not shown), and includes an oxygen-containing gas blowing lance 10 for blowing oxygen-containing gas into the tilting slag supply device 7.

  An oxygen-containing gas is blown into the tilting slag supply device 7 from the oxygen-containing gas blowing lance 10, and the combustible components of the exhaust gas entering the tilting slag supply device 7 from the reduction furnace 1 are burned, and the ambient temperature is set. Hold the molten slag at a high temperature. One or more oxygen-containing blowing lances 10 may be provided on the upper part 9 and / or the side part 8.

  The tilting slag supply device 7 is provided with a temperature measuring point (not shown) for measuring the ambient temperature on the side portion 8 adjacent to the opening 8a, and the weight of the device is provided below the tilting slag supply device 7. A weighing machine (not shown) capable of measuring at any time is arranged.

  The tilting slag supply device 7 is provided with a tilting device (not shown). The tilting slag supply device 7 is tilted about a tilting shaft (not shown) by the tilting device, and the molten slag charged from the charging port 14 is charged into the reduction furnace 1 via the charging port 4. .

  In the method of the present invention, the molten slag in the tilting slag supply device 7 is charged continuously or intermittently and statically into the reduction furnace 1, and then the new molten slag is tilted. From the hot metal ladle 11 until the tilting slag supply device 7 is in an empty state and held while the tilting slag supply device 7 is tilted. The hot metal 5 ′ is charged through the charging port 14, and the hot metal is supplied as it is to the reduction furnace 1 through the tilting slag supply device 7.

  The molten slag subjected to the reduction treatment is not limited to steelmaking slag. Any slag containing a valuable component may be used, or a slag obtained by mixing several slags may be used.

  In the empty state where the tilting slag supply device 7 has finished charging the molten slag into the reduction furnace 1, the bottom surface 9a of the device 7 is attached to the bottom surface 9a of the required thickness by which the molten slag has solidified as shown in FIG. 12 is attached. The adhered slag has a function of protecting the bottom surface of the tilting slag supply device, but the molten slag solidifies and accumulates while the molten slag is repeatedly charged, and the thickness increases.

  As the thickness of the attached slag at the bottom surface of the tilting slag supply device increases, the total weight of the tilting slag supply device increases or the slag capacity of the device decreases. Since an increase in the total weight of the tilting slag supply device and / or a decrease in the slag accommodation amount leads to replacement of the tilting slag supply device, it is necessary to always suppress the thickness of the adhered slag to a required thickness or less.

  In the method of the present invention, as shown in FIG. 1, the tilting slag supply device 7 is inclined at a required inclination angle θ1 (an angle formed by the bottom surface 9a and the horizontal plane), and the slag is fed from the hot metal ladle 11 to the device. When a predetermined amount of hot metal 5 ′ having a temperature exceeding the melting point is charged through the charging port 14, the surface layer of the adhered slag 12 is melted by the retained heat of the hot metal 5 ′ and flows out to the reduction furnace 1 together with the hot metal 5 ′.

  Even the adhering slag in which the molten slag having a low thermal conductivity is solidified is melted by the retained heat of the hot metal, so that the thickness of the adhering slag on the bottom surface of the tilting slag supply device can be reduced.

  FIG. 2 shows the relationship between the number of times molten slag is charged, the amount of molten slag charged, and the amount of adhesion when the method of the present invention is used. It can be seen that the amount of slag attached to the bottom surface of the slag supply device increases with an increase in the number of times of slag charging. For example, the number of slag insertions is 5 times, reaching approximately 30t.

  Here, when the method of the present invention was applied and the hot metal was passed through the slag supply device, the slag adhesion amount was reduced by about 8 t. This means that the attached slag has melted.

  The tilt angle θ1 of the tilting slag supply device is such that the bottom surface of the device is at least 10 ° from the horizontal plane. Preferably, it is 15 ° or more. The inclination angle θ1 is within an angle range in which the hot metal can sufficiently come into contact with the attached slag and can stably flow out to the reduction furnace in consideration of the attached state of the attached slag on the bottom surface of the inclined slag supply device. Set as appropriate. The upper limit of the tilt angle θ1 is the limit of the tilt angle of the tilting slag supply device or the limit at which hot metal can be introduced from the hot metal ladle through the inlet, but is actually assumed to be 30 ° or less.

  It was set in consideration of the state of the adhered slag on the bottom surface of the tilting slag supply device until the molten slag was charged in the reduction furnace and then the new molten slag was charged into the tilting slag supply device. The tilting slag supply device is tilted and held at an inclination angle θ1, and hot metal having a temperature exceeding the melting point of the slag is charged.

  The surface layer of adhering slag is melted by the retained heat of the hot metal, and the molten slag generated by melting rises and flows out together with the pig iron into the reduction furnace via the inlet, thus reducing the thickness of the adhering slag. Can do. The amount of pig iron charged in the tilting slag supply device held at the inclination angle θ1 is the thickness of the attached slag on the bottom surface of the tilting slag supply device, and the thickness of the slag layer necessary for protecting the bottom surface. Is set as appropriate.

At this time, oxygen-containing gas is blown in advance from an oxygen-containing gas blowing nozzle (see “10” in FIG. 1) so that the atmospheric temperature of the tilting slag supply device does not drop and the surface temperature of the attached slag layer does not drop. The combustible components (CO, H ₂ ) of the exhaust gas generated in the reduction furnace and entering the apparatus may be burned.

  Although the temperature exceeding the melting point of the hot metal slag cannot be limited to a specific temperature because the melting point of the slag depends on the component composition of the slag, for example, in the case of steelmaking slag whose component composition is substantially determined, it is approximately 1200 ° C. Therefore, the temperature exceeds 1200 ° C. However, since there is a temperature drop until the hot metal comes into contact with the attached slag and flows into the reduction furnace, the temperature of the hot metal charged into the tilting slag supply device is preferably 1400 ° C. or higher in consideration of this reduction.

  FIG. 3 shows another aspect of suppressing the growth of slag adhesion on the bottom surface of the tilting slag supply device. In the figure, the same members as those constituting the reduction furnace and the tilting slag supply device shown in FIG.

  In another aspect of the method of the present invention shown in FIG. 3, the molten slag in the tilting slag supply device is completely charged in the reduction furnace, and then a new molten slag is charged into the tilting slag supply device. Meanwhile, a required amount of hot metal 5 ′ having a temperature exceeding the melting point of the slag is introduced into the tilting slag supply device 7 in which the adhered slag 12 has grown thick on the bottom surface 9a, and the hot metal 5 ′ does not flow out to the reduction furnace. The tilting slag supply device is swung at a swing angle θ2 in the range (an angle formed by the bottom surface 9a with the horizontal plane).

  The peristaltic angle θ2 of the tilting slag supply device may be an angle within a range in which the hot metal does not flow out to the reduction furnace, and is appropriately determined in consideration of the adhesion state of the attached slag on the bottom surface of the tilting slag supply device and the amount of molten iron charged. Although it sets, the angle which the bottom part surface of a tilting-type slag supply apparatus makes with a horizontal surface is an angle of the range of -15 degrees--10 degrees (-: angle below a horizontal surface).

  The surface layer of the adhering slag is melted by the retained heat of the hot metal, and the molten slag generated by melting rises and flows out together with the pig iron into the reduction furnace via the inlet, so that the thickness of the adhering slag is reduced. The amount of pig iron introduced into the tilting slag supply device is appropriately set in consideration of the thickness of the attached slag on the bottom surface of the tilting slag supply device and the thickness of the slag layer necessary for protecting the bottom surface. .

At this time, the oxygen-containing gas is previously supplied from the oxygen-containing gas blowing nozzle (see “10” in FIG. 3) so that the atmospheric temperature of the tilting slag supply device does not decrease and the surface temperature of the attached slag does not decrease. The combustible components (CO, H ₂ ) of the exhaust gas that is blown in and generated in the reduction furnace and enters the apparatus may be combusted. As described above, the temperature exceeding the melting point of the hot metal slag is preferably 1400 ° C. or higher.

  Next, examples of the present invention will be described. The conditions in the examples are one example of conditions used for confirming the feasibility and effects of the present invention, and the present invention is based on this one example of conditions. It is not limited. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.

(Example)
First, the reduction furnace and tilting slag supply device used in the examples will be described.

(I) Reduction furnace The reduction furnace is a fixed hermetic reduction furnace with an input power of 30 MW, and the amount of molten iron in the furnace is 100 to 150 t and the amount of slag in the furnace is 40 to 70 t. The total amount of hot metal (150 t) was changed once per 10 h.

(II) Tilt-type slag supply device The tilt-type slag supply device has a slag capacity of 60 t, and the tilt angle of the bottom surface is −15 to + 20 ° with the horizontal plane as the reference plane (+: above the reference plane, − ; Below the reference plane). It is integrally connected to the reduction furnace and doubles as an exhaust gas flow path. One or a plurality of oxygen-containing gas blows are installed in the upper part or the side part close to the opening through which the steelmaking slag flows.

  In addition, a thermocouple for measuring the ambient temperature in the apparatus is installed on the side portion close to the opening. Furthermore, it is possible to measure the weight of the tilting slag supply device at any time below the tilting slag supply device.

(III) Dissolution of adhered slag by hot metal (III-1) In order to replace the entire amount of hot metal in the reducing furnace once every 10 hours, the entire amount of hot metal in the reducing furnace was discharged. Thereafter, the tilting-type slag supply device was tilted upward from the horizontal plane until the bottom surface became 10 ° or more, the lid of the slag inlet was opened, and hot metal at 1400 ° C. or more was charged for 100 t.

  The inclined slag supply device played a role of dredging, and the molten iron flowed directly to the reduction furnace along the bottom surface of the device. At this time, the surface layer of the adhering slag layer adhering to the bottom surface is in direct contact with the hot metal at 1400 ° C. or higher, so that the surface layer can be efficiently melted. The weight of the tilting slag supply device was 8t lower than the weight before the hot metal charging.

  (III-2) In order to replace the entire amount of hot metal in the reduction furnace once every 10 hours, the entire amount of hot metal in the reduction furnace was discharged. Thereafter, in order to increase the melting efficiency of the adhering slag, once the hot metal 50t of 1400 ° C. or higher is introduced into the tilting slag supply device, and the lid of the inlet is closed, the angle between the bottom surface and the horizontal plane is −15 ° to Between -10 degrees, the said apparatus was agitated and the hot metal was made to flow out to a reduction furnace. After repeating this operation twice, when the weight of the tilting slag supply device was measured, it was reduced by 10 tons.

  According to the present invention, even the adhered slag having a low thermal conductivity is melted and discharged to the reduction furnace, and the increase in the amount of adhered slag on the bottom surface of the tilting slag supply device is suppressed or the amount of adhered slag is reduced. Therefore, direct charging of the molten slag into the reduction furnace can be stabilized, and stable operation of the reduction furnace can be ensured. Therefore, the present invention has high applicability in the steel industry and the slag utilization industry.

DESCRIPTION OF SYMBOLS 1 Reduction furnace 1a, 1b Side wall 1c Top cover 1d Furnace bottom 2 Electrode 3 Inlet 4 Inlet pipe 5, 5 'Hot metal 6 Molten slag 7 Tilt-type slag supply apparatus 8 Side part 8a Opening 9 Bottom part 9a Bottom part 9b Upper part 10 Oxygen containing gas Blow lance 11 Hot metal pan 12 Adhering slag 13 Exhaust port 14 Input port θ1 Inclination angle θ2 Peristaltic angle

Claims (6)

In the tilting slag supply device that also serves as the exhaust gas path of the reduction furnace, in the reduction process in which molten slag is continuously or intermittently charged into the reduction furnace and the slag is reduced, the bottom surface of the tilting slag supply device A method for suppressing an increase in the amount of slag adhered by solidification,
The tilting slag supply device is required until the molten slag in the tilting slag supply device has been charged into the reduction furnace and then the new molten slag is charged into the tilting slag supply device. Tilt-type slag, characterized in that it is held at an inclination angle of, and hot metal having a temperature exceeding the melting point of the slag is charged, and the hot metal is directly charged into a reduction furnace through a tilt-type slag supply device. A method for suppressing slag adhesion of a supply device.   2. The slag adhesion of the tilting slag supply device according to claim 1, wherein the inclination angle is an angle formed by a bottom surface of the tilting slag supply device and a horizontal plane, and is an angle of 10 ° or more above the horizontal plane. Suppression method. In the tilting slag supply device that also serves as the exhaust gas path of the reduction furnace, in the reduction process in which molten slag is continuously or intermittently charged into the reduction furnace and the slag is reduced, the bottom surface of the tilting slag supply device A method for suppressing an increase in the amount of slag adhered by solidification,
In the tilting slag supply device, the molten slag in the tilting slag supply device has been charged into the reduction furnace, and then the new molten slag is charged into the tilting slag supply device. A method for suppressing slag adhesion in a tilting slag supply device, wherein hot metal having a temperature exceeding the melting point of the slag is charged, and the tilting slag supply device is swung at a swing angle in a range in which the hot metal does not flow out to the reduction furnace. .   4. The tilting slag supply according to claim 3, wherein the swing angle is an angle formed by a bottom surface of the tilting slag supply device and a horizontal plane, and is an angle in a range of 15 ° to 10 ° below the horizontal plane. A method of suppressing slag adhesion of a device.   The temperature of the hot metal is 1400 ° C or higher, and the slag adhesion suppressing method of the tilting slag supply device according to any one of claims 1 to 4.   The adhesion slag suppression method for a tilting slag supply device according to any one of claims 1 to 5, wherein the molten slag is a steelmaking slag in a molten state.

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