JP5491764B2 - Furnace wall structure of molten metal manufacturing furnace and method for suppressing wear of furnace wall refractories - Google Patents

Description

  The present invention relates to a molten metal production furnace for producing a molten metal mainly containing iron by melting an iron-containing raw material, and more particularly to a furnace wall structure of a molten metal production furnace and a method for suppressing wear of a furnace wall refractory.

  Liner refractories are used to protect the furnace body in electric furnaces or converter-type metal melting furnaces and metal smelting furnaces, but since the temperature of the molten metal and exhaust gas is high and the refractory liners melt, The repair material is sprayed on the damaged part to extend the life of the refractory.

  However, in order to spray the repair material, it is necessary to periodically stop the operation of the furnace, and the operation rate of the furnace decreases. In particular, when the melting rate of the refractory is high, the repair frequency increases, and the basic unit of the repair material also increases, resulting in an increase in the manufacturing cost of the molten metal.

  Therefore, in recent years, for the purpose of reducing furnace material costs and reducing the burden of repair work, a water-cooled panel is installed on the back of the refractory to forcibly cool down, ”) Is made a water-cooled structure instead of a refractory structure, and attempts have been made to suppress refractory melting of the entire furnace (see, for example, Patent Documents 1 and 2). ).

  However, in the method using the water-cooled panel or the water-cooled structure, the heat efficiency of the furnace decreases due to an increase in the amount of heat removed by water cooling, so the energy intensity increases. Moreover, in addition to high initial equipment costs, there is a risk of causing a water vapor explosion by reacting with the molten metal in the furnace in the case of water leakage in operation, which is difficult to manage. Furthermore, the energy recovered with the cooling water cannot be effectively used because of its low temperature, resulting in an increase in the manufacturing cost of the molten metal.

  On the other hand, as a new iron making method that replaces the conventional blast furnace and smelting reduction method, the applicant of the present invention preliminarily reduced the carbonaceous agglomerate in a rotary hearth furnace to form solid reduced iron. The hot metal manufacturing process which melt | dissolves and obtains hot metal was proposed (refer patent document 3).

  However, when this process is put to practical use, in order to further reduce the manufacturing cost of molten metal mainly composed of iron such as pig iron, a lining is used in a melting furnace (molten metal manufacturing furnace) without using a water cooling panel or a water cooling structure. There has been a strong demand for the development of technology that can suppress the wear of refractories (furnace wall refractories).

JP-A-8-20814 JP-A-8-291316 JP 2007-291252 A

  Accordingly, an object of the present invention is to provide a furnace wall structure and a method for suppressing the wear of a furnace wall refractory that can suppress the wear of the furnace wall refractory without using a water cooling panel or a water cooling structure in a molten metal production furnace. And

The invention according to claim 1 is a furnace wall structure of a molten metal production furnace for producing a molten metal mainly composed of iron by melting an iron-containing raw material, and includes a refractory layer inside the iron skin. The protective iron plate can be lowered by providing a certain gap inside the refractory layer, and a carbonaceous material agglomerated ore and / or reduced iron derived from the carbonaceous material agglomerated mineral (hereinafter, “ A supply means for supplying a carbonaceous material-incorporated agglomerated mineral or the like.) The protective iron plate is soaked in a slag layer at its lower end, and in order from the furnace ceiling in order to compensate for the melted portion A furnace wall structure of a molten metal production furnace, characterized in that it can be supplied .

  The invention according to claim 2 is the furnace wall structure of the molten metal production furnace according to claim 1, wherein the molten metal production furnace is cylindrical.

  The invention according to claim 3 is the molten metal manufacturing furnace having the furnace wall structure according to claim 1 or 2, wherein the protective iron plate has its lower end immersed in a slag layer in the furnace, Filling gaps with carbonaceous material agglomerated minerals, etc., the protective iron plate is sequentially supplied from the furnace ceiling of the molten metal production furnace to compensate for the melted, A method for suppressing wear of a furnace wall refractory in a molten metal production furnace, wherein the melted portions are sequentially replenished.

  In the invention according to claim 4, the amount of carbon remaining after the carbonaceous material agglomerated mineral or the like has reduced the metal oxide to the metal with carbon of the interior carbonaceous material is the carbonaceous material agglomerated mineral or the like. 4. The method for suppressing wear of a furnace wall refractory in a molten metal production furnace according to claim 3, wherein the content is 5% by mass or more based on mass.

  According to the present invention, the heat load on the refractory layer is reduced by covering the high heat load portion of the refractory layer with a protective iron plate and a carbonaceous material-incorporated agglomerate, and a water-cooled panel or a water-cooled structure is used. In addition, the melting rate of the refractory layer can be reduced. As a result, the energy intensity can be reduced, the refractory life can be extended, and the molten metal cost can be further reduced.

It is a flowchart which shows the outline of the hot metal manufacturing equipment based on implementation of this invention. It is a section perspective view showing the outline of the furnace wall structure of the hot metal manufacturing furnace concerning the implementation of the present invention.

(Embodiment)
Regarding the present invention, reduced iron (HBI) derived from a carbonaceous material agglomerated ore as an iron-containing raw material, hot metal as a molten metal mainly composed of iron, and a molten metal production furnace as an example of a molten metal production furnace This will be described in detail.

  FIG. 1 shows a schematic flow of hot metal production equipment according to the embodiment of the present invention. Carbonaceous material agglomerated ore is heated and reduced in a rotary hearth furnace (not shown) to produce reduced iron A, and this reduced iron A is hot-formed with a hot briquette machine at a high temperature to form HBI (hot briquette iron). A ′. Then, HBI A ′ as an iron-containing raw material is charged into an iron bath melting furnace (hot metal production furnace) 1 together with coal as a melting heat source and carburizing material, quick lime as a flux, etc., and oxygen is blown up. Then, HBI A ′ is dissolved to produce hot metal B as a molten metal.

  Next, FIG. 2 shows an outline of the furnace wall structure of the hot metal production furnace. The hot metal production furnace 1 includes a refractory layer 3 inside an iron shell 2, a fixed gap 4 is further provided inside the refractory layer 3, and a protective iron plate 5 can be lowered. A supply means 7 for supplying reduced iron (after cooling) 6 derived from a material-incorporated agglomerated mineral is provided.

  Thereby, since the surface of the refractory layer 3 is covered with the packed layer of the reduced iron 6 and further with the protective iron plate 5, the refractory layer 3 does not come into direct contact with the corrosive hot gas or slag, Moreover, since the packed layer of reduced iron 6 functions as a heat insulating layer, the surface temperature of the refractory 3 is kept low, and the refractory layer 3 is effectively prevented from being damaged.

  The protective iron plate 5 is preferably in a state where its lower end is immersed in the slag layer D in the furnace so that the surface of the refractory layer 3 can be completely isolated from the corrosive high temperature gas. The protective iron plate 5 is preferably made of a high melting point low carbon (for example, C: 0.5 mass% or less) steel plate so as not to melt immediately even when exposed to a high-temperature furnace atmosphere. Further, even if a part of the protective iron plate 5 is melted, the protective iron plate 5 is configured to be lowered. Therefore, the protective iron plate 5 may be lowered sequentially by the amount of the molten metal. Moreover, the protective iron plate 5 is installed so as to protrude upward from the furnace ceiling of the hot metal production furnace 1, and is configured so that it can be sequentially supplied from the furnace ceiling according to the amount of erosion loss. The physical layer 3 can be protected.

  Further, since the protective iron plate 5 is made of iron, even if it is melted, it only becomes a part of the hot metal, so there is no problem.

  The reduced iron 6 filled in the gap 4 between the protective iron plate 5 and the refractory layer 3 forms a filled layer upward from the surface of the metal layer C, but the reduced iron 6 in contact with the metal layer C is Although it dissolves sequentially in C, it is possible to maintain a packed bed of reduced iron 6 in the gap 4 by sequentially supplying the amount corresponding to the dissolved amount by the supply means 7. Further, even if the reduced iron 6 is melted, it only becomes a part of the hot metal and slag, so no problem arises.

  If the thickness of the protective iron plate 5 is too thin, the strength will be insufficient. On the other hand, if the thickness is too thick, the weight will be excessive and the mechanism for lowering will be increased in size and cost will increase. For example, 2-10 mm, 3-8 mm, In particular, 4 to 6 mm is recommended.

  Moreover, in order to avoid the stress concentration by the deformation | transformation and distortion by the heat | fever of the protection iron plate 5, it is preferable that the hot metal manufacturing furnace 1 is made into a vertical cylinder shape, and the protection iron plate 5 is also formed in a vertical cylinder shape. In this case, there is no problem in manufacturing if the inner diameter of the protective iron plate 5 is about 2 m, for example.

  The size of the gap 4 between the refractory 3 and the protective iron plate 5 is at least twice as large as the average diameter of the reduced iron 6 and more than three times in order to sufficiently exhibit the heat insulation effect by the packed bed of the reduced iron 6. It is preferable to do this. However, if the gap 4 is too large, the thickness of the entire furnace wall becomes excessive, and the ratio of the effective volume of the melting part to the total volume of the furnace body decreases, so that the average diameter of the reduced iron 6 is 6 times or less, and further 5 It is recommended to keep it under twice.

  The reduced iron 6 is the carbon of the interior carbonaceous material remaining without being consumed by the reduction in the rotary hearth furnace, and the unreduced iron oxide (metal oxide) is reduced to metallic iron (metal). It is preferable to contain carbon so that the amount of carbon remaining later is 5 mass% or more with respect to the mass of the reduced iron 6. Thereby, since the reduced iron 6 is carburized with the contained carbon and melts at a very low temperature of about 1200 ° C., the surface temperature of the protective iron plate 5 in contact with the reduced iron 6 can be kept at a low temperature of about 1200 ° C., It is possible to more reliably prevent the protective iron plate 5 from being melted. In order to obtain such reduced iron 6, it is preferable to adjust the amount of interior carbon material blended in the carbon material interior agglomerated before being charged into the rotary hearth furnace (before reduction).

(Modification)
In the said embodiment, although HBI which hot-formed high temperature reduced iron was illustrated as the iron containing raw material A, you may use the reduced iron cooled by the shape (pellet shape or briquette shape) as it is, without hot forming. .

  Moreover, in the said embodiment, although reduced iron (HBI) derived from a carbonaceous material agglomerated ore was exemplified as the iron-containing raw material A, gas-based reduced iron, scrap, cold iron, etc. may be used alone, Alternatively, two or more of these can be used in combination.

  Moreover, in the said embodiment, although the case where hot metal was manufactured as the molten metal B mainly containing iron was illustrated, this invention is applicable also when manufacturing molten alloy irons, such as ferrochrome, ferromanganese, and ferronickel. In this case, the iron-containing raw material A may be an alloy iron raw material containing non-ferrous metals such as Cr, Mn, and Ni as main components in addition to Fe.

  Moreover, in the said embodiment, although the example using only reduced iron (thing after reduction | restoration) derived from a carbonaceous material agglomerated mineral was shown as carbonaceous material agglomerated mineral 6 etc., a carbonaceous material agglomerated mineral (unreduced) May be used alone or in combination.

  In particular, when using only unreduced materials, or when using both unreduced materials and those after reduction, they are heated by heat transfer from the high temperature part in the furnace, Since unreduced iron oxide is reduced by the interior carbon material and a large amount of caloric gas mainly composed of CO is generated, for example, a vent hole is provided in the furnace ceiling above the gap 4, and this caloric gas is recovered. It is recommended to use it effectively.

  In addition, when using only the above unreduced one, or when using both the unreduced one and the one after reduction, the reduction of iron oxide by the interior carbon material is an endothermic reaction. It can be expected that the heat insulation effect is enhanced as compared with the case of using only.

  In the above embodiment, an example in which the reduced iron A is filled in the gap 4 between the refractory layer 3 and the protective iron plate 5 is shown. However, another protective iron plate is installed so as to be in contact with the inner surface of the refractory layer 3. Reduced iron A may be filled between two protective iron plates. Thereby, although equipment cost rises, it becomes possible to suppress the wear of a refractory layer more reliably.

  Moreover, in the said Example, although the iron bath melting furnace was illustrated as a hot metal manufacturing furnace, this invention is applicable also to an electric furnace.

1: Molten metal production furnace (hot metal production furnace)
2: Iron skin 3: Refractory layer 4: Gap 5: Protective iron plate 6: Carbonaceous material agglomerated mineral (reduced iron derived from carbonaceous material agglomerated mineral)
7: Supply means A: Iron-containing raw material (reduced iron derived from carbonaceous material agglomerated ore, HBI)
B: Molten metal (hot metal)
C: Metal layer D: Slag layer

Claims (4)

A furnace wall structure of a molten metal production furnace for producing a molten metal mainly containing iron by melting an iron-containing raw material, comprising a refractory layer on the inner side of the iron shell, and further on the inner side of the refractory layer Provided with a certain gap so that a protective iron plate can be lowered, and in the gap, a carbonaceous material agglomerated mineral and / or reduced iron derived from the carbonaceous material agglomerated mineral (hereinafter referred to as “carbonaceous material agglomerated mineral”) The protective iron plate is constructed so that its lower end is immersed in a slag layer and can be sequentially supplied from the furnace ceiling in order to compensate for the melted portion. A furnace wall structure for a molten metal manufacturing furnace, characterized in that:   The furnace wall structure of the molten metal production furnace according to claim 1, wherein the molten metal production furnace is cylindrical. The molten metal manufacturing furnace having a furnace wall structure according to claim 1 or 2, wherein the protective iron plate has its lower end immersed in a slag layer in the furnace, and a carbonaceous material agglomerated mineral or the like in the gap. filled with the protective iron plate, as well as the manufacturing molten metal furnace of the furnace roof or al sequentially supplied to compensate for erosion was divided, the carbonaceous material interior mass Naruko etc., to sequentially supply the dissolved amount A method for suppressing the wear of a furnace wall refractory in a molten metal production furnace.   The amount of carbon remaining after the carbonaceous material agglomerated or the like has reduced the metal oxide to the metal with the carbon of the interior carbonaceous material is 5% by mass or more based on the mass of the carbonaceous material agglomerated mineral or the like. The method for suppressing wear of a furnace wall refractory in a molten metal production furnace according to claim 3.

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