JP6460293B2 - Method for producing sintered ore - Google Patents

Description

  The present invention relates to a method for producing sintered ore used as an ironmaking raw material in a blast furnace or the like. Specifically, the present invention relates to a two-layer carbonaceous material-containing sintered ore (carbonaceous material interior) in which the periphery of the carbonaceous material core is coated with a mixed powder containing iron-containing raw material powder such as iron ore powder and CaO-containing raw material powder. The present invention relates to a method for producing agglomerated minerals) with a sintering machine.

  In the blast furnace ironmaking method, massive ore, sintered ore, pellets, and the like are currently used as ironmaking raw materials. Here, the sintered ore is obtained by charging the quasi-particles, which are raw materials for sinter ore production, into a pallet that circulates in the sintering machine, burning the solid fuel contained in the quasi-particles, and sintering it. It is a kind of agglomerated ore obtained by crushing and sizing the resulting sintered cake and recovering a product having a certain particle size or more as a product. The pseudo particles include an iron-containing raw material, a CaO-containing raw material, a secondary raw material as a melting point adjusting agent other than the CaO-containing raw material, and a granulated raw material including a solid fuel (carbon material) that is a coagulant such as powdered coke or anthracite. It is manufactured by adding an appropriate amount of water to the mixture, mixing and granulating using a drum mixer or the like.

As the iron-containing raw material constituting the pseudo particles, in addition to iron ore having a particle size of 10 mm or less, dust generated in the place, mill scale, and the like are used. As the CaO-containing raw material, limestone, quicklime, slag, or the like is used. As auxiliary materials other than the CaO-containing material, a melting point adjusting agent, SiO ₂ -containing materials such as silica, serpentine, dolomite and refined nickel slag, and MgO-containing materials such as magnesia clinker and dolomite are used.

  In addition, pellets are iron-making raw materials produced by the steps of grinding or adjusting iron ore, producing raw pellets with a granulator, drying, firing, and cooling the produced raw pellets. It is a kind.

  In recent years, the agglomeration has attracted attention as a material in which iron-containing raw materials such as iron ore and dust and carbon materials such as coke are arranged in close proximity. This is because, for example, when an iron-containing raw material such as iron ore and a carbon material are arranged close together in one agglomerate, a reduction reaction (exothermic reaction) on the iron-containing raw material side and a gasification reaction (endothermic reaction) on the carbon material side This is because the reaction) occurs repeatedly at a high speed, thereby improving the reduction efficiency and lowering the temperature in the furnace such as a blast furnace.

  As the agglomerate, for example, Patent Document 1 discloses that coal containing raw material powder generated in the iron making process such as blast furnace dust, converter dust, rolling scale, sludge, iron ore powder, or the like is used as a raw material. An iron-making raw material pellet is disclosed in which a carbonaceous material such as coke and coke and starch are added, mixed and kneaded, and further supplied with a starch solution with a granulator to be granulated. However, since the pellet disclosed in Patent Document 1 burns away the carbonaceous material in the pellet at the time of firing, the iron-containing raw material such as iron ore and the carbonaceous material are actually arranged close to each other. Not. If the particle size of iron ore or charcoal is simply reduced for the purpose of close placement in this pellet manufacturing process, the resistance to the movement of the heat-propagating gas becomes too high, and on the contrary, the reaction rate decreases. Invites reduction efficiency.

  Then, some techniques aiming at the proximity | contact arrangement | positioning of an iron-containing raw material and a carbon material are proposed (for example, refer patent documents 2-5). The technology disclosed in these is basically a mixture of iron-containing raw materials such as iron ore and carbonaceous materials such as coke, and then agglomerated by hot forming or without firing. The raw particles are used as raw materials for iron making in blast furnaces. However, since these agglomerates are non-fired products made of a uniform mixture or a multilayered granulated product, the strength is insufficient and the powdering is intense. Therefore, if these are inserted into a blast furnace or the like, dehydration or reduction powdering is caused and the air permeability of the blast furnace is hindered, so that there is a problem that the amount used is limited.

  Moreover, the technique which solves the problem of the technique of patent documents 2-5 is proposed. For example, in Patent Document 6, a core is formed of a raw material containing 5% by mass or more of metallic iron and / or 5% by mass or more of carbon, and a raw material containing 10% by mass or more of metallic iron and 5% by mass or less of carbon. A method for producing an agglomerate for iron making is proposed, in which one or more outer peripheral layers containing the nucleus are formed and then fired and agglomerated in an oxidizing atmosphere at 300 to 1300 ° C. However, in the production method disclosed in Patent Document 6, it is essential to use metallic iron as a raw material, and since there are quantitative restrictions on the raw material used, there is a restriction on the amount that can be produced as an agglomerate for iron making. There is a problem that there is.

  Then, carbon material interior agglomeration has been proposed as a technique for overcoming the above-mentioned problems of Patent Documents 1-6.

  For example, in Patent Document 7, iron oxide powder containing metal iron such as iron-making dust and mill scale is coated around a carbon material core made of small coke by using a granulator and has a low oxidation degree. After forming the iron oxide shell, the iron oxide shell having a high oxidation degree is applied only to the surface of the iron oxide shell by performing an oxidation treatment in the atmosphere at a temperature of 200 ° C. or higher and lower than 300 ° C. for 0.5 to 5 hours. Carbonaceous interior agglomerated minerals with a hard thin layer made of

  In Patent Document 8, iron oxide powder such as iron-making dust or mill scale or iron ore powder and charcoal are mixed and granulated using a granulator, and then metallic iron is formed on the outer surface of the granulated product. Is coated with iron oxide powder containing a low oxidation degree, and after the formation of the iron oxide shell, it is heated in the atmosphere at a temperature of 200 ° C. or higher and lower than 300 ° C. for 0.5 to 5 hours. The coke powder having a size of 3 mm or less is dispersed in the iron oxide powder or iron ore powder in which a hard thin layer made of iron oxide having a high degree of oxidation is formed only on the surface of the iron oxide shell. Carbonaceous material agglomerates have been proposed.

  In Non-Patent Document 1, a green ball is prepared by coating an anthracite coal on a green ball and coating the pellet feed with the anthracite coal. The result of having evaluated the reactivity in the atmosphere in a blast furnace about the carbonaceous material inclusion sintered ore which carried out the sintering by charging a sintering raw material is reported.

JP 2001-348625 A JP 2001-294944 A JP 2001-303143 A JP 2005-344181 A JP 2002-241853 A JP-A-10-183262 JP 2011-195943 A JP 2011-225926 A

CAMP-ISIJ vol. 24 (2011), 194

  As described above, Patent Document 7 and Patent Document 8 have an appropriate size and sufficient strength as an iron-making raw material, and the iron-containing raw material and the carbonaceous material are arranged close to each other, easily cause an iron-making reaction, and have a low temperature. A carbonaceous agglomerated mineral with a structure that can be reduced is disclosed.

  However, in patent document 7 and patent document 8, the coating layer which consists of a low oxidation degree iron oxide shell is formed using the iron oxide powder containing metallic iron, and as this iron oxide powder containing metallic iron, Since the generation amount of suitable iron-making dust, mill scale, and the like is limited, there is a problem that the production amount of the carbonaceous material agglomerated mineral is limited. If iron oxide powder containing metallic iron is intentionally produced as a raw material for the production of carbonaceous agglomerated minerals, the production cost of the carbonaceous material agglomerated minerals will increase, and the ironmaking process will be reduced. The problem of efficiency arises. In addition, Patent Document 7 and Patent Document 8 do not mention anything about the method for producing the carbonaceous material-containing granulated particles used for the production of the carbonaceous material-containing agglomerated mineral.

  The present invention has been made in view of the above circumstances, and its purpose is to limit the production amount without using iron oxide powder containing metallic iron such as iron dust and mill scale. By providing a method for producing a sintered ore that can produce a two-layered carbon material-containing sintered ore (coal material-containing agglomerated mineral) in which the iron-containing raw material and the carbon material are arranged close to each other. is there.

  The inventors of the present invention have made extensive studies to solve the above problems. As a result, first, carbonaceous material-containing granulated particles having a two-layer structure in which a carbonaceous material core is covered with a mixed powder containing iron ore powder and CaO-containing raw material powder are produced. Next, the iron oxide powder containing metal iron such as iron-making dust and mill scale is used by firing the particles of this two-layer structure with the pseudo-particles that are the raw material for conventional sinter ore production. The present inventors have found that it is possible to produce a two-layered carbonaceous material-containing sintered ore in which the iron-containing raw material and the carbonaceous material are arranged close to each other. Moreover, the water content at the time of manufacturing the carbonaceous material-internally granulated particles is set to 8 to 10% by mass of the total mass of the mixed powder, the carbonaceous material core, and the moisture, that is, The present inventors have found that controlling the water content during granulation of granule particles to 8 to 10% by mass is effective in terms of strength of the carbonaceous material-containing granule particles produced.

The present invention has been made based on the above findings, and the gist thereof is as follows.
[1] Charcoal material obtained by firing carbon material-containing granulated particles having a two-layer structure in which a carbon material core is coated with a mixed powder containing iron-containing raw material powder and CaO-containing raw material powder with a pallet of a sintering machine A method for producing a sintered ore for producing an interior sintered ore,
The carbonaceous material-containing granulated particles are a method for producing a sintered ore in which the water content at the time of granulation is 8 to 10% by mass of the total mass of the carbonaceous material core, the mixed powder, and moisture.
[2] The method for producing a sintered ore according to [1], wherein the iron-containing raw material powder is iron ore powder, and the mixed powder is composed of iron ore powder and CaO-containing raw material powder.
[3] The sintering machine together with the sintered raw material of the pseudo-particles obtained by adding water to the iron-containing raw material, CaO-containing raw material, solid fuel (carbonaceous material), mixing and granulating the carbon-containing granulated particles. The method for producing a sintered ore according to [1] or [2] above, wherein the sintered ore is fired on a pallet.
[4] The sintered ore production method according to [3], wherein the pseudo-particle sintering raw material further includes an auxiliary raw material as a melting point adjusting agent other than the CaO-containing raw material.
[5] A part of the moisture contained in the carbonaceous material-containing granulated particles according to any one of the above [1] to [4], which is previously contained in the mixed powder before granulation. A method for producing sintered ore.
[6] Manufacture of sintered ore according to any one of [1] to [5], wherein a part of moisture contained in the carbonaceous material-containing granulated particles is newly added during granulation. Method.

  According to the present invention, iron-containing raw material powder such as iron ore powder and CaO-containing raw material powder are surrounded around the carbonaceous material core without using iron oxide powder containing metal iron such as iron dust and mill scale. It is possible to manufacture a two-layered carbon material-containing sintered ore (carbon material-containing agglomerated mineral) covered with the mixed powder.

  Moreover, since the moisture content at the time of granulation of the carbonaceous material-incorporated granulated particles is 8 to 10% by mass, the carbonaceous material-incorporated granulated particles are converted into the conventional sinter-manufactured pseudo particles in the sintering machine. When firing together with the sintered raw material, it is possible to produce carbonaceous material-containing granulated particles having a strength that can withstand the load applied by the surrounding charged raw materials. As a result, the outer layer of the carbon material-containing granulated particles is not broken and the carbon material core is not exposed, and the carbon material can be efficiently left in the sintered ore.

FIG. 1 is a schematic view showing an example of a granulation facility for producing carbonaceous material-containing granulated particles for producing a carbonaceous material-containing sintered ore. FIG. 2 is a graph showing the relationship between the water content and the crushing strength at the time of granulation of the carbonaceous material-containing granulated particles. FIG. 3 is a graph showing the relationship between the water content at the time of granulation of the carbonaceous material-containing granulated particles and the maximum temperature reached in the inner and lower layers of the sintered layer. FIG. 4 is a graph showing the relationship between the moisture content at the time of granulation of the carbonaceous material-containing granulated particles, the reducibility of the carbonaceous material-containing sintered ore, and the residual carbon concentration of the carbonaceous material-containing sintered ore. . FIG. 5 is a graph showing the crushing strength of the carbonaceous material-containing granulated particles in levels 11 to 14 in Example 2.

  Hereinafter, the present invention will be specifically described.

  In the present invention, a carbonaceous material-containing granulated particle having a two-layer structure in which the periphery of a carbon material core is coated with a mixed powder containing a powder of an iron-containing raw material such as iron ore powder and a powder of a CaO-containing raw material is fired by a sintering machine. Thus, this is a technique for producing a two-layer carbonaceous material-containing sintered ore in which an iron-containing raw material and a carbonaceous material are arranged close to each other. In the present specification, a carbon material core is used as a core, and the carbon material core is covered with a mixed powder containing iron-containing raw material powder and CaO-containing raw material powder. The carbon material-containing granulated particles are defined as “two-layered carbon material-containing granulated particles”.

  When producing a two-layered carbonaceous material-containing sintered ore, in the sintering process of the sintering machine, by performing the sintering process together with the pseudo particles that are the raw material for conventional sintered ore production, The combustion heat of the solid fuel contained in the pseudo particles, which are raw materials for the production of sintered ore, can be effectively used as a heat source for firing the carbon material-containing granulated particles. It is realized to produce (material interior agglomerate).

Here, the sintered raw material of pseudo particles, which is a raw material for producing conventional sinter ore, is an iron-containing raw material, a CaO-containing raw material, a secondary raw material as a melting point adjusting agent other than a CaO-containing raw material, and powdered coke, anthracite, etc. It is manufactured by adding an appropriate amount of water to a granulated raw material containing solid fuel (carbonaceous material), which is a coagulant, and mixing and granulating using a drum mixer or the like. As the iron-containing raw material, in addition to iron ore having a particle size of 10 mm or less, dust generated in the place, mill scale, and the like are used. As the CaO-containing raw material, limestone, quicklime, slag, or the like is used. As auxiliary materials other than the CaO-containing material, a melting point adjusting agent, SiO ₂ -containing materials such as silica, serpentine, dolomite and refined nickel slag, and MgO-containing materials such as magnesia clinker and dolomite are used.

  FIG. 1 shows an example of a granulation facility for producing carbonaceous material-containing granulated particles for the production of carbonaceous material-containing sintered ore. In FIG. 1, reference numeral 1 is a granulation facility, 2 a is a hopper that contains iron-containing raw material powder, 2 b is a hopper that contains CaO-containing raw material powder, 2 c is a hopper that contains carbonaceous materials, 3 a, 3 b, 3 c, 3d is a conveyor, 4 is a kneader, 5 is a granulator, and 6 is a water supply pump. The manufacturing method of the carbonaceous material-containing granulated particles used when manufacturing the carbonaceous material-containing sintered ore according to the present invention will be described with reference to FIG.

  The powder of the iron-containing raw material and the powder of the CaO-containing raw material as a melting point modifier are charged into the kneader 4 via the transport device 3a, and the iron-containing raw material powder and the CaO-containing raw material powder are uniformly mixed by the kneader 4 Mix. The mixed powder formed by uniform mixing of the iron-containing raw material powder and the CaO-containing raw material powder is discharged from the kneading machine 4, and the discharged mixed powder is charged into the granulator 5 through the transporter 3c. At the same time when the mixed powder is charged into the granulator 5 or before and after the mixed powder is charged into the granulator 5, a carbon material (coke particles) having a particle diameter of 3.0 mm or more serving as core particles ) Is charged into the granulator 5 through the transfer machine 3b and the transfer machine 3c.

  Here, the iron-containing raw material powder is any one or two or more kinds of powder concentrates or crushed iron ore powders after the selection of iron ore, and iron-making dust or mill scale generated in the facility. It is a mixture. The particle size of the iron-containing raw material need not be specified as long as granulation is possible, but there is no problem as long as the particle size is about 1.0 mm or less. The present invention produces a two-layer carbonaceous material-containing sintered ore in which the iron-containing raw material and the carbonaceous material are arranged close to each other without using iron oxide powder containing metallic iron such as iron dust or mill scale. However, the present invention does not prohibit the use of iron-making dust, mill scale, or the like generated at steelworks as iron-containing raw materials.

Moreover, as a powder of the CaO containing raw material used when manufacturing the carbonaceous material interior granulated particles, any of the powders of quick lime (CaO), limestone (CaCO ₃ ), and slaked lime (Ca (OH) ₂ ) One or a mixture of two or more is preferred. The particle size of the CaO-containing raw material need not be defined as long as granulation is possible, but there is no problem as long as the particle size is about 1.0 mm or less.

  Water is supplied to the mixed powder mixed in the kneading machine 4 through the water supply pump 6 and / or water is supplied to the granulator 5 through the water supply pump 6. The water content with respect to the granulation raw material (total mass of the carbonaceous material, mixed powder and water) at the time of granulation is adjusted to 8 to 10% by mass. By adjusting the moisture content of the carbonaceous material-containing granulated particles at the time of granulation to 8 to 10% by mass, the carbonaceous material having a large particle size is used as a core, and the iron-containing raw material powder and the CaO-containing raw material are surrounded around it. The mixed powder in which the powder is uniformly mixed is coated by the liquid crosslinking force of water. Thus, the carbonaceous material-containing granulated particles having a two-layer structure in which the periphery of the carbonaceous material core is coated with the mixed powder containing the powder of the iron-containing raw material and the powder of the CaO-containing raw material are formed. The formed carbon material-containing granulated particles have a carbon material core with a diameter of 3 to 10 mm, a coating layer thickness of 7 mm or less, and a particle diameter of 8.0 mm to 24.0 mm.

  Then, the carbonaceous material-containing granulated particles produced in this way are conveyed to, for example, a Dwydroid-type sintering machine, and then the carbonaceous material-containing granulated particles and the sintered raw material of the pseudo-particles for producing conventional sinter ore Are mixed together and mixed with carbonaceous material-internally granulated particles and a conventional sintered raw material of pseudo-particles for producing sinter ore and carried into a surge hopper of a sintering machine. In this case, from the viewpoint of effectively using the combustion heat of the solid fuel contained in the sintered raw material pseudo particles as a heat source for firing the carbonaceous internal granulated particles, the mass of the carbonaceous internal granulated particles and the sintered raw material pseudo particles is It is preferable to join the two so that the ratio falls within the range of 1: 9 to 3: 7.

In addition to the iron ore, as mentioned above, the sintering raw material of pseudo particles for producing conventional sintered ore includes CaO-containing raw materials such as limestone and quicklime, SiO2 such as silica stone, serpentine, and refined nickel slag. _2. Add a suitable amount of water to a granulated raw material containing a secondary raw material as a melting point modifier such as a raw material, solid fuel (charcoal) such as powdered coke and anthracite, and mix and granulate using a drum mixer. Hereinafter, the conventional sintering raw material of pseudo particles is also referred to as “sintering raw material pseudo particles”.

  Through a surge hopper that contains the carbonaceous material-inner granulated particles and the sintered raw material pseudo particles, the carbonaceous material-inner granulated particles and the sintered raw material pseudoparticles are mixed in the sintered machine circulation. Load the moving pallet. Then, the sintering process of the carbonaceous material interior granulated particles and the sintered raw material pseudo particles charged in the pallet is performed.

  In the sintering process, the solid fuel contained in the sintered raw material pseudo particles charged in the pallet is ignited in an ignition furnace of a sintering machine. After ignition, the solid fuel contained in the sintered raw material pseudoparticles burns sequentially from the upper part of the charged raw material layer toward the lower part, and the sintering reaction and sintering reaction between the sintered raw material pseudoparticles by the combustion heat of this solid fuel. The conventional sinter is produced. At the same time, the coating layer of the mixed powder containing the powder of the iron-containing raw material and the powder of the CaO-containing raw material on the surface layer side of the carbonaceous material-containing granulated particles is fired by the combustion heat of the solid fuel contained in the sintered raw material pseudo particles, Sintering reaction, further melting reaction proceeds, and has an unburned carbon material inside, and the surface layer side is a carbon material interior having a strong coating layer containing iron-containing raw material powder and CaO-containing raw material powder Sinter is produced.

  After the sintering treatment, the formed sintered cake containing the carbonaceous material-containing sintered ore and the conventional sintered ore is crushed and sized, and a product having a certain particle size or more is recovered as a product. Although the carbonaceous material-containing sintered ore is recovered in a state where the conventional sintered ore is fused around the carbonaceous material-containing sintered ore, there is no problem in use as a steelmaking raw material in a blast furnace.

  In addition, since the carbonized material-incorporated granulated particles have a particle size larger than that of the conventional sintered raw material pseudo-particles, the temperature during sintering is higher than the upper side of the pallet due to segregation during charging into the pallet of the sintering machine. In the middle layer side of the pallet and the lower layer side of the pallet, and the sintering reaction of the carbonaceous material-containing granulated particles and the conventional sintering raw material can sufficiently proceed.

  When only iron ore powder is used as the iron-containing raw material powder, the carbonaceous material-containing sintered ore does not use iron oxide powder containing metallic iron such as iron dust or mill scale, and existing Since it can manufacture using a sintering machine, it is realized to produce in large quantities without restricting the production amount without preparing a new firing facility.

  Therefore, in the present invention, it is preferable to use only iron ore powder as the iron-containing raw material powder, and use a mixed powder composed of iron ore powder and CaO-containing raw material powder as the mixed powder covering the periphery of the carbonaceous material core. .

  Conventionally, by adjusting the moisture content of the granulation raw material (a combination of the carbonaceous material, mixed powder and moisture) supplied to the granulator to 8-10% by mass in the production of the carbonaceous material-incorporated granulated particles. Can be granulated by using a granulator used in, for example, either or both of a disk pelletizer and a drum mixer.

  In the present invention, the upper limit of the moisture content at the time of granulation is set to 10% by mass. When the moisture is excessive, coarse granulated particles that greatly exceed the specified particle diameter of 24.0 mm are generated in the granulator. This is to prevent generation of the coarse granulated particles. That is, if the moisture content during granulation exceeds 10% by mass, the voids between the powdered iron-containing raw materials will be filled with moisture above the crosslinking moisture, and the moisture will act like a lubricant. The coarse particles are very weak and the coating layer is broken by the load applied by the surrounding raw materials in the sintered layer, so that the carbon material core is exposed, and the carbon material core is lost by combustion. Because it ends up. Furthermore, the coating layer of coarse granulated particles is broken, so that air passages in the sintered layer are blocked, and air permeability as a sintering process may be hindered.

  On the other hand, the lower limit of the moisture content at the time of granulation is set to 8% by mass. When the moisture at the time of granulation is less than 8% by mass, the moisture as a cross-linking for binding particles of the iron-containing raw material powder is insufficient. However, the granulated particles are not formed in the first place, or the granulated particles have a very low strength. Also in this case, as in the case where the moisture is excessive, the coating layer of the granulated particles is broken in the sintered layer, and the carbon material core is exposed and lost by combustion.

  When the carbon material core is lost, the speeding up phenomenon of the reaction due to the close arrangement of the iron-containing raw material and the carbon material as described above is lost, and the effect of improving the reducibility cannot be obtained.

  As described above, according to the present invention, iron-containing raw material powder and CaO-containing raw material powder are surrounded around the carbonaceous material core without using iron oxide powder containing metallic iron such as iron dust or mill scale. It is realized to produce a two-layered carbonaceous material-containing sintered ore coated with a mixed powder containing.

  Moreover, since the moisture content at the time of granulation of the carbonaceous material-incorporated granulated particles is 8 to 10% by mass, the carbonaceous material-incorporated granulated particles are used as a sintering raw material for conventional sinter production in a sintering machine. When firing together with the pseudo particles, it is possible to produce carbonaceous material-containing granulated particles having a strength that can withstand the load applied by the surrounding charged materials. Thereby, it is prevented that the outer layer of the carbon material-containing granulated particles is broken and the carbon material core is exposed, and the carbon material can be efficiently left in the sintered ore.

  Note that the present invention is not limited to the above-described range. For example, as a heat source for firing carbonaceous material-containing granulated particles, in addition to the combustion heat of solid fuel contained in conventional sintered raw material pseudoparticles, In addition, a sintering technique for supplying gaseous fuel, and a sintering technique for supplying oxygen gas in an enriched manner can also be used.

  Changed moisture content during granulation to produce two-layered carbonaceous material-incorporated granulated particles, and produced carbonaceous material-incorporated granulated particles, as well as sintered raw materials that were separately produced as raw materials for conventional sintered ore. Charcoal obtained by mixing the particles, sintering the mixed carbon material-containing granulated particles and sintered raw material pseudo particles with a sintering machine, and firing the carbon material-containing granulated particles and the carbon material-containing granulated particles. A test was conducted to investigate the effect of moisture content during granulation on the internal sinter. Two-layered carbon material-containing granulated particles were produced using the granulation equipment shown in FIG.

As carbon material-internally-granulated particles having a two-layer structure, as a carbon material core, dry coke having a particle diameter of 4 to 5 mm is used, and as an iron-containing raw material powder that forms a coating layer covering the outer periphery of the carbon material core. A dry pellet feed powder (hematite (Fe ₂ O ₃ ): 97.7% by mass) having a particle diameter of 250 μm or less was used. Moreover, quick lime powder (CaO) having a particle diameter of 200 μm or less as a melting point adjusting agent was used as the powder of the CaO-containing raw material forming the coating layer covering the outer periphery of the carbonaceous material core. These raw materials are charged into a granulator and mixed, and water is added to the raw material in the granulator through a spray nozzle so that the coating layer has a thickness of 3 mm or more and a particle diameter of 12 to 16 mm. Granulated granulated particles were prepared and used for testing. The water content of the carbonaceous material-containing granulated particles during granulation was changed to 6 levels of levels 1 to 6 within a range of 6 to 11% by mass. Table 1 shows the water content of the carbonaceous material-containing granulated particles during granulation in levels 1 to 6.

  On the other hand, as a sintered raw material pseudo particle that is a raw material of a conventional sintered ore, as an agglomerated raw material, iron ore powder and limestone as an auxiliary raw material with an amount of CaO of 10% by mass in the sintered raw material pseudo particle The coke powder | flour as a solid fuel of the quantity in which powder and the amount of cokes become 5 mass% in sintering raw material pseudoparticles was used. These raw materials were charged into a drum mixer, stirred and mixed, and sintered raw material pseudo particles granulated to a particle diameter of 2.9 mm in arithmetic average diameter were prepared and used for the test.

  The crushing strength of each of the carbonaceous material-incorporated granulated particles of Levels 1 to 6 produced in this way was measured using a method defined in JISM8717. Further, the prepared carbonaceous material-incorporated granulated particles of level 1 to 6 and the sintered raw material pseudo particles were mixed at a ratio of carbonaceous material-internally granulated particles: sintered raw material pseudo particles = 2: 8, and mixed charcoal. The material-incorporated granulated particles and the sintered raw material pseudo particles were subjected to sintering treatment in a pot-type sintering test apparatus having a lattice-shaped disk and having a height: 400 mm × diameter: 300 mm.

  FIG. 2 shows the relationship between the water content and the crushing strength at the time of granulation of the carbonaceous material-containing granulated particles. It is calculated that 1.0 MPa or more is necessary as the strength with which the coating layer of the carbonaceous material-containing granulated particles can withstand the load applied from the surrounding charged raw material without breaking in the inner and lower layers of the sintered layer. From FIG. 2, it was found that when the water content of the carbonaceous material-containing granulated particles at the time of granulation was 8 to 10% by mass, the crushing strength was 1.0 MPa or more, and the above condition was satisfied.

  In FIG. 3, the relationship between the water content at the time of granulation of carbonaceous material interior granulation particle | grains and the highest achieved temperature in a sintered layer inner lower layer is shown. As shown in FIG. 3, when the water content is in the range of 8 to 10% by mass, the water content is 6% by mass, 7% by mass, and 11% by mass as compared with the maximum temperature of 1340 ° C. or less. % Indicates that the maximum temperature reached has increased. The sintered raw material pseudo particles, which are the raw materials of the conventional sintered ore subjected to the sintering treatment at the same time, have the same blending amount of the mixed powder coke regardless of the conditions. Therefore, when the moisture content is 6% by mass, 7% by mass, and 11% by mass, the coating layer of the carbonaceous material-containing granulated particles is broken, and the inner carbonaceous material core is partially burned, and this reaches the maximum. It is thought that the temperature has increased.

  Moreover, in FIG. 4, the relationship between the water content at the time of granulation of a carbonaceous material interior granulated particle, the reducibility of a carbonaceous material interior sintered ore, and the residual carbon concentration of a carbonaceous material interior sintered ore is shown. As shown in FIG. 4, the residual carbon concentration was reduced under the conditions where the water content was 6 mass%, 7 mass%, and 11 mass%. Including the results of FIG. 3 above, it can be seen that the internal carbon material nuclei are partially burned under the conditions where the water content is 6 mass%, 7 mass%, and 11 mass%. Moreover, the reducibility decreased due to a decrease in the residual carbon concentration of the carbonaceous material-containing sintered ore.

  The total value of the moisture previously added to the mixed powder before granulation and the moisture added by the spray nozzle at the time of granulation was 9% by mass, which showed high crushing strength in the test of Example 1, and both A test for changing the ratio into four types of levels 11 to 14, producing a two-layered carbon material-containing granulated particle by the same method as in Example 1, and investigating the crushing strength of the produced carbon material-containing granulated particle Went. The raw material of the carbonaceous material-incorporated granulated particles is the same as the raw material used in Example 1 for the carbonaceous material core, the iron-containing raw material powder, and the CaO-containing raw material powder.

  Table 2 shows the breakdown of moisture previously added to the mixed powder and moisture added by the spray nozzle during granulation in levels 11 to 14.

  In FIG. 5, the crushing intensity | strength of the carbonaceous material interior granulated particle in the levels 11-14 is shown. As is apparent from FIG. 5, it can be seen that there is no significant change in the crushing strength of the carbonaceous material-containing granulated particles at any level. Therefore, the moisture content at the time of granulation of the carbonaceous material-containing granulated particles may be either the moisture previously contained in the mixed powder or the moisture added during granulation, and the total value is important. It was.

DESCRIPTION OF SYMBOLS 1 Granulation equipment 2a, 2b, 2c Hopper 3a, 3b, 3c, 3d Conveyor 4 Kneading machine 5 Granulator 6 Water supply pump

Claims (6)

Carbonaceous material-containing granulated particles having a two-layer structure in which the carbonaceous material core is coated with a mixed powder containing iron-containing raw material powder and CaO-containing raw material powder are fired on a sintering machine pallet to sinter the carbonaceous material. A method for producing a sintered ore for producing ore,
The carbonaceous material- containing granulated particles are a total amount of moisture previously contained in the mixed powder before granulation and moisture added at the time of granulation. And a method for producing a sintered ore that is 8 to 10% by mass of the total mass of the mixed powder and moisture.   The method for producing sintered ore according to claim 1, wherein the iron-containing raw material powder is iron ore powder, and the mixed powder is composed of iron ore powder and CaO-containing raw material powder. Said carbonaceous material interior granulated particles, iron-containing material, CaO-containing material, water was added to the solid fuel is a condensation material, together with the sintering raw material granulated pseudo particles are mixed, the pallet of the sintering machine The manufacturing method of the sintered ore of Claim 1 or Claim 2 baked by.   The sintered ore production method according to claim 3, wherein the pseudo-particle sintering raw material further includes a secondary raw material as a melting point adjusting agent other than the CaO-containing raw material.   The part of the water | moisture content contained in the said carbonaceous material interior granulated particle is previously contained in the said mixed powder before granulation, The manufacture of the sintered ore of any one of Claim 1 thru | or 4 Method.   The method for producing a sintered ore according to any one of claims 1 to 5, wherein a part of water contained in the carbonaceous material-containing granulated particles is newly added during granulation.

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