JP6446970B2 - 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 the 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 slag on the bottom surface of the slag supply device or reduces the solidification adhesion amount of slag, thereby reducing the molten slag to the reduction furnace (hereinafter referred to as “melting”). In particular, it is intended to stabilize the direct charging of molten steelmaking slag and to ensure stable operation of the reduction furnace, and to provide a method for suppressing slag adhesion that solves the problem With the goal.

  The inventor has intensively studied a method for solving the above problems. As a result, when the slag supply device is empty, if the device is tilted and the ambient temperature of the device is maintained at a required high temperature, the surface layer of slag (adhering slag) that has solidified and adhered to the bottom surface of the slag supply device Is melted and flows out to the reduction furnace, and then the newly exposed surface layer of the attached slag melts and flows out to the reduction furnace, so that the increase in the amount of solidified slag on the bottom surface of the slag supply device can be suppressed as much as possible. I found it.

  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,
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,
The tilting slag supply device is held with the bottom surface of the device tilted by 10 ° or more from the horizontal plane , and the atmospheric temperature of the device is maintained at a temperature exceeding the melting point of the slag,
The outflow of surface melting of the slag adhering to the bottom surface of the device into the reducing furnace, tilting type slag, characterized in that the deposition amount of the slag at the bottom surface of the tilting type slag feeder below a predetermined amount A method for suppressing slag adhesion of a supply device.

( 2 ) An oxygen-containing gas is blown into the tilting slag supply device, the combustible component of the exhaust gas generated in the reduction furnace and entering the device is burned, and the ambient temperature of the device exceeds the melting point of the slag. The slag adhesion suppressing method of the tilting slag supply device according to the above (1 ), wherein the method is held as described above.

( 3 ) When the amount of exhaust gas generated in the reduction furnace and passing through the tilting slag supply device is small, a combustible gas is blown into the reduction furnace and is induced and burned into the tilting slag supply device. The method for suppressing adhesion of slag in a tilting slag supply device according to (1 ) above, wherein the atmospheric temperature of the device is maintained at a temperature exceeding the melting point of the slag.

( 4 ) The temperature exceeding the melting point of the slag is 1200 ° C. The method for suppressing slag adhesion of the tilting slag supply device according to any one of (1) to ( 3 ).

(5) The slag adhesion suppressing method for a tilting slag supply device according to (2 ), wherein a burner is disposed around the tilting slag supply device instead of the squeezing of the oxygen-containing gas.

( 6 ) The slag adhesion suppressing 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 adhesion slag having a low thermal conductivity is melted and allowed to flow out to the reduction furnace, and an increase in the amount of slag adhesion on the bottom surface of the slag supply device is suppressed or the amount of slag adhesion is reduced. Therefore, it is possible to stabilize the direct charging of the molten slag into the reduction furnace and ensure stable operation of the reduction furnace.

It is a figure which shows the aspect which suppresses slag adhesion to 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 the relationship between the charging frequency of molten slag, the charging amount of molten slag, and the adhesion amount in this invention.

The method for suppressing slag adhesion of the tilting slag supply device of the present invention (hereinafter sometimes referred to as “the method of the present invention”)
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,
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,
The tilting slag supply device is held with the bottom surface of the device tilted by 10 ° or more from the horizontal plane , and the atmospheric temperature of the device is maintained at a temperature exceeding the melting point of the slag,
The outflow of surface melting of the slag adhering to the bottom surface of the device to the reduction furnace, characterized in that the deposition amount of the slag at the bottom surface of the tilting type slag feeder below a predetermined amount.

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

  In FIG. 1, the aspect which suppresses slag adhesion to 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 and a combustible gas blowing lance 3 that penetrates the upper lid 1c. 1 is provided with an inlet 4 for molten slag that is supplied by a tilting slag supply device 7 that is disposed integrally with the slag 1. 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. In addition, you may install the combustible gas blowing lance 3 so that removal is possible.

  The tilting slag supply device 7, which is integrally connected to the reduction furnace 1 at the charging port 4 and serves as an exhaust gas discharge path of the reduction furnace 1, temporarily supplies molten slag supplied by a slag pan (not shown). , Storing and holding, and then flowing into the reduction furnace 1 continuously or intermittently and statically into the molten slag 6 layer on the hot metal 5 through the inlet 4 while controlling the flow rate. It is.

  The tilting slag supply device 7 is composed of a bottom portion 9 made of a non-water-cooled refractory wall, an upper portion 9b made of a water-cooled refractory wall, and a side portion 8, and a molten slag is formed on a surface facing the side portion 8. It has an opening 8a that flows out, an exhaust port 13 that exhausts the gas in the tilting slag supply device 7 in an upper part 9b, and an input port 14 that a slag pan (not shown) inputs molten slag (the lid that closes the input port is And an oxygen-containing gas blowing nozzle 10 for blowing oxygen-containing gas into the tilting slag supply device 7.

  An oxygen-containing gas blowing nozzle is used to burn the combustible components of the exhaust gas entering the tilting slag supply device 7 from the reducing furnace 1, maintain the atmospheric temperature at a high temperature, melt the attached slag, and flow it out to the reducing furnace. 10, oxygen-containing gas is blown into the tilting slag supply device 7. One or more oxygen-containing blowing nozzles 10 may be provided in the upper part 9b and / or the side part 8.

  By providing an oxygen-containing gas blowing nozzle, it is possible to constantly heat up the atmosphere in the device to the vicinity of the tip without arranging a burner facility with a large occupied area around the tilting slag supply device And the amount of exhaust gas can be reduced. However, if the existing burner equipment can be used, the burner equipment is used.

  The tilting slag supply device 7 is provided with a temperature measuring point for measuring the ambient temperature at the side portion 8 adjacent to the opening 8a, and the weight of the device is measured at the lower part of the tilting slag supply device 7 as needed. A weighing machine (not shown) is arranged.

  The tilting slag supply device 7 is provided with a tilting device (not shown). The tilting device is tilted with a tilting slag supply device 7 about a tilting axis (not shown), and the molten slag generated by melting the surface layer of the solidified slag is passed through the inlet 4 in the reduction furnace 1. Spill.

The method of the present invention is a tilting-type slag supply device that also serves as an exhaust gas path of a reduction furnace, and after the molten slag has been charged continuously or intermittently and statically into the reduction furnace, then a new molten state Until the slag is introduced into the tilting slag supply device, the tilting slag supply device is held with the bottom surface of the device tilted at least 10 ° from the horizontal plane , and the ambient temperature of the device is adjusted to the melting point of the slag. held at a temperature in excess of, the outflow of surface melting of the slag adhering to the bottom surface of the device into the reducing furnace, to the adhesion amount of the slag at the bottom surface of the tilting type slag feeder below a predetermined amount It is characterized by.

  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.

  The molten slag is continuously or intermittently and statically charged into the reduction furnace until the new molten slag is charged into the tilting slag supply device, that is, the tilting type. While the slag supply device is empty, the tilting slag supply device is tilted and held, and the atmospheric temperature of the device is maintained at a temperature exceeding the melting point of the slag. This is a feature of the method of the present invention.

  In an empty state in which the tilting slag supply device has charged molten slag into the reduction furnace, solidified slag is adhered to the bottom surface of the device with a required thickness. Adhering slag has the function of protecting the bottom surface of the tilting slag supply device, but accumulates and increases in thickness during repeated charging of molten slag.

  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. It can be seen that the amount of slag deposited on the bottom surface of the slag supply device increases with an increase in the number of slag charging. For example, the number of slag insertions is 5 times, reaching approximately 30t.

  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 the increase in the total weight and / or the decrease in the storage amount leads to the replacement of the tilting slag supply device, it is necessary to always suppress the thickness of the attached slag to a required thickness or less.

  If the tilting slag supply device is tilted and the atmospheric temperature of the device is maintained at a required high temperature, the surface layer of the attached slag on the bottom surface of the slag supply device melts and flows out to the reduction furnace, and then is newly exposed. The surface layer of the adhered slag melts and flows out to the reduction furnace. Even a solidified slag having a low thermal conductivity is melted by being exposed to a high temperature, so that an increase in the thickness of the adhered slag on the bottom surface of the inclined slag supply device can be suppressed as much as possible.

  FIG. 3 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. As shown in FIG. 3, even when the number of slag charging is increased, the amount of slag attached to the bottom surface of the slag supply device is maintained at about 20 t or less. The difference is obvious compared to the relationship.

  The tilt angle of the tilting slag supply device is such that the bottom surface of the device is 10 ° or more from the horizontal plane. Preferably, it is 15 ° or more. The inclination angle is appropriately set in consideration of the form of attached slag on the bottom surface of the inclined slag supply device.

An oxygen-containing gas is blown into the tilting slag supply device, and the combustible components (CO, H ₂ ) of the exhaust gas generated in the reduction furnace and intruded into the device are combusted, and the atmospheric temperature of the device exceeds the melting point of the slag Hold at temperature.

  When the amount of exhaust gas entering the tilting slag supply device from the reduction furnace is small, a combustible gas is blown into the reduction furnace, and the gas is induced and burned into the tilting slag supply device to create an atmosphere. Maintain the temperature above the melting point of the slag.

  Although the temperature exceeding the melting point of the slag depends on the component composition of the slag and cannot be limited to a specific temperature, for example, in the case of steelmaking slag in which the component composition is substantially determined, 1200 ° C. or higher is preferable.

  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. A flammable gas injection nozzle was detachably installed on the upper lid of the reduction furnace.

(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 blowing nozzles 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, a weighing machine capable of measuring the weight of the device at any time is installed at the lower part of the tilting slag supply device.

Example 1
(1) Molten steelmaking slag 30t was introduced from the slag pot into the tilting slag supply device from the inlet.

  (2) The tilting-type slag supply device was tilted and charged into the reduction furnace from the charging inlet intermittently at 5 to 10 t at an average of 1 t / min.

(3) After the slag charging into the reduction furnace has been completed and the tilting slag supply device has been emptied, a waiting time of 10 minutes has occurred until the next slag charging. While tilting up to 0 ° C., oxygen 2,000 Nm ³ / h was blown from an oxygen-containing gas blowing lance to burn the combustible components of the exhaust gas flowing in from the reduction furnace, and the ambient temperature was raised. Note that the CO concentration was measured with an analyzer placed on the outlet side of the tilting slag supply device, and was almost zero, so it was confirmed that there was no shortage of oxygen.

  (4) At that time, since the atmospheric temperature measured by the thermocouple provided in the tilting slag supply device was 1230 ° C., it was held for 10 minutes in the same posture (inclination of + 20 °). As a result, the total weight of the tilting slag supply device was reduced by 2 t compared to before the start of oxygen gas blowing. It was found that the reduced 2t slag melted and flowed into the reduction furnace.

(Example 2)
(1) Although the same operation as in Example 1 was performed, the arrival of molten slag from the slag pan was delayed, the amount of exhaust gas entering the tilting slag supply device from the reduction furnace was reduced, and the tilting type The atmospheric temperature of the slag supply device decreased to 1150 ° C.

(2) Therefore, the reduction furnace, a combustible gas blowing lance, coke oven gas (COG) 2,000 Nm ³ / h blowing, blowing of oxygen 2,000 Nm ³ / h from the oxygen-containing gas blowing lance Continued.

  (3) As a result, the atmospheric temperature of the tilting slag supply device recovered to 1200 ° C. or higher, so that the inclination (+ 20 °) of the tilting slag supply device was maintained and the arrival of the molten slag was awaited.

  (4) When the molten slag arrives 30 minutes later and the weight of the tilting slag supply device at that time is measured, the weight is determined by blowing the combustible gas due to surface melting of the adhered slag and outflow to the reduction furnace. It was reduced by 3 tons from the weight at the time of loading.

  According to the present invention, even adhesion slag having a low thermal conductivity is melted and allowed to flow out to the reduction furnace, and an increase in the amount of slag adhesion on the bottom surface of the slag supply device is suppressed or the amount of slag adhesion is reduced. Therefore, it is possible to stabilize the direct charging of the molten slag into the reduction furnace and ensure stable operation of the reduction furnace. 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 Combustible gas injection nozzle 4 Charging inlet 5 Hot metal 6 Molten slag 7 Slag supply apparatus 8 Side part 8a Opening 9 Bottom part 9a Bottom part 9b Upper part 10 Oxygen containing gas injection Nozzle 11 Temperature measuring point 12 Adhering slag 13 Outlet 14 Inlet

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,
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,
The tilting slag supply device is held with the bottom surface of the device tilted by 10 ° or more from the horizontal plane, and the atmospheric temperature of the device is maintained at a temperature exceeding the melting point of the slag,
A tilting slag characterized in that the amount of slag adhering to the bottom surface of the tilting slag supply device is reduced to a predetermined amount or less by surface melting of the slag adhering to the bottom surface of the device and outflow to a reduction furnace. A method for suppressing slag adhesion of a supply device.   An oxygen-containing gas is blown into the tilting slag supply device, generated in a reduction furnace, and combustible components of exhaust gas entering the device are combusted, and the atmospheric temperature of the device is maintained at a temperature exceeding the melting point of the slag. The method for suppressing adhesion of slag in a tilting slag supply device according to claim 1.   When the amount of exhaust gas generated in the reduction furnace and passing through the tilting slag supply device is small, a combustible gas is blown into the reduction furnace and is induced to burn in the tilting slag supply device. The method for suppressing slag adhesion of a tilting slag supply device according to claim 1, wherein the temperature is maintained at a temperature exceeding the melting point of the slag.   The temperature exceeding the melting | fusing point of the said slag is 1200 degreeC, The slag adhesion suppression method of the tilting-type slag supply apparatus of any one of Claims 1-3 characterized by the above-mentioned. The method for suppressing adhesion of slag in a tilting slag supply device according to claim 2, wherein a burner is disposed around the tilting slag supply device instead of the nozzle that blows in the oxygen-containing gas.   The method for suppressing slag adhesion of 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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