Method for producing sintered ore

Abstract

To produce sintered ore having higher quality by using a mixed dry distilled material obtained by mixing iron ore with biomass and dry distilling the mixture.SOLUTION: A particle size adjustment step of adjusting the particle size of the biomass and the iron ore to a predetermined particle size, a carbonization step of carbonizing a mixture of the biomass and the iron ore having the adjusted particle size to produce a mixed carbonized product which is a mixture of a biomass carbide and a reduced ore, and a sintering step of producing sintered ore using the mixed carbonized product, wherein the predetermined particle size of the biomass is a top size of 3 mm or more and 7 mm or less, and the predetermined particle size of the iron ore is a top size of 7 mm or more and 10 mm or less, wherein a particle diameter ratio of a top size is 0.3 or more, a mass ratio of the biomass and the iron ore in the mixture is 0.2 or more, a dry distillation temperature in the dry distillation step is 700 °C or more and 900 °C or less, and a reduction rate of the reduced ore produced in the dry distillation step based on hematite is 70% or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present application relates to a method for producing sintered ore. [Background technology]

[0002] In order to reduce CO2 emissions from sintering machines that produce sintered ore, biomass, a so-called carbon-neutral carbonaceous material, has been used as a sintering carbonaceous material (agglomerate). Patent Document 1 discloses an invention in which a mixture of biomass and an iron-containing material (iron ore), each pulverized to a specific particle size, is carbonized in a rotary furnace, and the resulting mixed carbonized product is used in an iron-making process. The invention discloses that the mixed carbonized product, which is biomass charcoal and the carbon-precipitated iron-containing material, can be pulverized or molded as is without classification and used in the iron-making process. The invention also discloses that after separating the biomass charcoal and the carbon-precipitated iron-containing material by classification based on differences in specific gravity, the biomass charcoal can be used as a reducing agent and the iron-containing material can be used as an iron source in the iron-making process. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-51676 Summary of the Invention [Problem to be solved by the invention]

[0004] However, Patent Document 1 does not disclose anything about producing sintered ore using the mixed dry distillate or the biomass charcoal and iron-containing material obtained by classifying the mixed dry distillate as raw materials for sintering.

[0005] The present application aims to provide a method for producing higher quality sintered ore by mixing iron ore and biomass, carbonizing the mixture, and using the resulting carbonized mixture. [Means for solving the problem]

[0006] The present application has been made to solve the above problems, and its gist is as follows.

[0007] (1) a particle size adjustment step of adjusting the particle sizes of the biomass and the iron ore to predetermined particle sizes; a dry distillation step of dry distilling the mixture of the biomass and the iron ore whose particle size has been adjusted in the particle size adjustment step to produce a mixed dry distillate which is a mixture of biomass carbide and reduced ore which is reduced iron ore; a sintering step of producing sintered ore using the mixed dry distillate produced in the dry distillation step, The predetermined particle size of the biomass adjusted in the particle size adjustment step is 3 mm or more and 7 mm or less in top size, The predetermined particle size of the iron ore is 7 mm or more and 10 mm or less in top size, The particle size ratio of the biomass to the top size of the iron ore (top size of biomass / top size of iron ore) is 0.3 or more, The mass ratio of the biomass to the iron ore in the mixture (mass of biomass / mass of iron ore) is 0.2 or more, The dry distillation temperature in the dry distillation step is 700°C or higher and 900°C or lower, A method for producing sintered ore, wherein the reduced ore produced in the dry distillation step has a reduction rate of 70% or less based on hematite.

[0008] (2) a separation step of separating the mixed dry distillate into the biomass charcoal and the reduced ore by magnetic separation, gravity separation, or flotation separation; and a consolidation step of compressing the biomass charcoal separated in the separation step to produce a consolidated biomass charcoal. In the sintering step, sintered ore is produced using the compacted biomass carbide and the reduced ore separated in the separation step, The reduction rate of the reduced ore produced in the dry distillation step is 11% or more based on hematite, The densified biomass charcoal used in the sintering step has an apparent density of 0.6 g / cm 3 The method for producing sintered ore according to (1) above, characterized in that the top size is 7 mm or less.

[0009] (3) The consolidation step a compression step of compressing and molding the biomass carbonized material to produce a compressed product; a grinding step of grinding the compressed product; (2) A method for producing sintered ore according to (2) above, further comprising a sizing step of sizing the pulverized material produced in the pulverization step.

[0010] (4) The method for producing sintered ore according to (3) above, characterized in that in the sizing step, the crushed material that falls under the 5 mm sieve and over the 1 mm sieve is used as the consolidated biomass carbide in the sintering step.

[0011] (5) In the sizing step, The pulverized material on the 5 mm sieve is returned to the pulverization step. The method for producing sintered ore according to (4) above, wherein the crushed material that falls below the 1 mm sieve is returned to the compression step. [Effects of the Invention]

[0012] According to the present application, it is possible to provide a method for producing higher quality sintered ore by mixing iron ore and biomass, carbonizing the mixture, and using the resulting carbonized mixture. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 2 is a diagram illustrating a flow of a method for producing sintered ore according to an embodiment. [Figure 2] FIG. 4 is a diagram illustrating a flow of a method for producing sintered ore according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] (First embodiment) The method for producing sintered ore according to this embodiment will be described with reference to the drawings. Fig. 1 is a diagram illustrating the flow of the method for producing sintered ore according to this embodiment. The method for producing sintered ore according to this embodiment uses biomass and iron ore as raw materials and includes a biomass particle size adjustment step 1, an iron ore particle size adjustment step 2, a blending step 3, a carbonization step 4, and a sintering step 10. The biomass is used as a carbonaceous material for sintering (agglomerating agent).

[0015] The biomass used in the method of this embodiment may be any biomass. For example, woody biomass (such as cedar chips, beech, and cypress), palm kernel shells (PKS), waste-based biomass (such as sewage sludge, almond shells, walnut shells, rice husks, rice straw, and municipal solid waste), and food-based biomass (such as coffee grounds) can be used. Biomass other than those listed here may also be used.

[0016] Iron ore is an iron oxide-containing raw material used to produce sintered ore for blast furnaces. In this embodiment, any iron ore may be used. For example, hematite (Fe2O3) may be used. One type of iron ore may be used, or multiple types of iron ores may be mixed and used.

[0017] Each step of the sintered ore manufacturing method will be described. First, in particle size adjustment steps 1 and 2, particle size adjustment is performed on the raw materials, biomass and iron ore, respectively. In particle size adjustment steps 1 and 2, the raw materials are adjusted to a predetermined top size. The top size is the maximum particle size (nominal top size) specified in JIS K 2151 (2004) Cokes - Testing Method. Specifically, the top size is the size of the smallest sieve opening (nominal dimension) of a test sieve (JIS Z 8801-2, see square holes) that results in a sieve retention rate of 5% or less of the sample. Hereinafter, the top size in this embodiment refers to the particle size determined by this method.

[0018] In the particle size adjustment step 1, the top size of one of the raw materials, biomass, is adjusted. Specifically, the top size can be adjusted to 3 mm or more and 7 mm or less. By adjusting the top size of the biomass to 3 mm or more and 7 mm or less, the biomass charcoal obtained after the dry distillation step 4 (hereinafter also referred to as "biomass charcoal") functions more effectively as a carbon material in the sintering step. Biomass of a predetermined top size can be obtained by sieving the biomass through a sieve with the openings of the corresponding top size and collecting the biomass that falls below the sieve. For example, to obtain biomass with a top size of 5 mm, the biomass can be sieved through a sieve with 5 mm openings and the biomass that falls below the sieve can be collected. Note that if biomass whose top size has been adjusted to the specified range in advance is used as the raw material biomass, the particle size adjustment step 1 may be omitted.

[0019] In the particle size adjustment step 2, the top size of the other raw material, iron ore, is adjusted. Specifically, the top size can be adjusted to 7 mm or more and 10 mm or less. By adjusting the top size of the iron ore to 7 mm or more and 10 mm or less, excessively large iron ore can be removed. Excessively large iron ore may not be reduced sufficiently in the carbonization step 4 and may hinder the production of homogeneous sintered ore in the sintering step 10. Iron ore of a specified top size can be obtained by collecting iron ore that falls below the sieve openings of the specified top size, as with biomass. Note that if iron ore such as fine ore for sintering, whose top size has been adjusted to the specified range in advance, is used as the raw iron ore, the particle size adjustment step 2 may be omitted.

[0020] The particle size ratio of the biomass and iron ore that have been adjusted in particle size adjustment steps 1 and 2 and are then fed to the next blending step 3 can be 0.3 or more. The particle size ratio is the ratio of the top sizes, (Top size of biomass / Top size of iron ore) If the particle size ratio is less than 0.3, it may be difficult to mix the biomass and iron ore in the next blending step 3, which may result in uneven reduction of the iron ore. The upper limit of the particle size ratio can be 1 or less. In other words, the particle size ratio can be 0.3 or more and 1 or less.

[0021] Next, in the blending step 3, biomass of a predetermined top size and iron ore are blended in a predetermined mass ratio. The predetermined mass ratio (dry basis) is (mass of biomass / mass of iron ore) The mass ratio can be set to 0.2 or more and 3 or less. If the mass ratio is less than 0.2, it may be difficult to reduce the iron ore to an appropriate reduction rate in the subsequent carbonization step 4. If the mass ratio exceeds 3, the effect of heat generated by the reduced ore in the sintering step 10 is reduced, which is undesirable. Furthermore, the mass ratio between the two is preferably 0.5 or more and 1 or less. Within this range, the reduction rate of the iron ore in the carbonization step 4 can be further improved. In the blending step 3, the biomass and iron ore can be blended using a hopper or the like so as to achieve the above-mentioned mass ratio. The raw materials may be directly charged into the carbonization apparatus from the hopper, or they may be blended in another container and then charged into the carbonization apparatus. In the blending step 3, the raw materials blended at the above-mentioned mass ratio may be stirred and mixed using a mixer or the like. The stirring process improves the contact between the biomass and iron ore in the carbonization apparatus, making it easier to reduce the iron ore to an appropriate reduction rate.

[0022] Next, in the carbonization step 4, the mixture of biomass and iron ore blended in the blending step 3 is carbonized. This mixture is a mixture blended at the above-mentioned predetermined particle size (top size and particle size ratio) and predetermined mass ratio. In the carbonization step 4, the biomass is carbonized and carbonized, and the iron ore can be reduced. The carbonization step 4 can produce a mixture of biomass charcoal and reduced iron ore (hereinafter also referred to as "reduced ore"). The mixture of biomass charcoal and reduced ore produced in the carbonization step 4 will hereinafter also be referred to as "mixed carbonized product." In the carbonization step 4, the iron ore can be carbonized (heated) to a predetermined reduction rate. Furthermore, in the carbonization step 4, the iron ore can be carbonized at a predetermined carbonization temperature. A specific description will be given below.

[0023] First, in the carbonization step 4, when the raw iron ore before reduction is hematite, it is preferable to carbonize (heat) the iron ore so that the reduction rate of the iron ore is 70% or less. To achieve a reduction rate of more than 70%, the conditions of the carbonization step 4 must be made stricter. For example, it is necessary to lengthen the reaction (retention) time, increase the particle size ratio of biomass to iron ore, or increase the mass ratio. Such strict conditions of the carbonization step 4 may result in reduced productivity and increased equipment costs. The lower limit of the reduction rate of the iron ore is not particularly limited in this embodiment, but can be set to 11% or more, for example, when the raw iron ore is hematite. A reduction rate of 11% or more reduces the hematite in the iron ore to magnetite, enabling separation using magnetic separation in the separation step described in the second embodiment. In other words, when the raw iron ore is hematite, the carbonization step 4 can reduce the iron ore to a reduction rate in the range of 11% to 70%.

[0024] The reduction rate of iron ore (reduction rate based on hematite) is an index that represents the percentage of oxygen actually removed by reduction, relative to the theoretical amount of oxygen (amount of oxygen in iron oxide before reduction) that is removed when reducing the iron in the raw material to metallic iron (M-Fe), assuming that all the iron in the raw material is hematite (Fe2O3). In this embodiment, the reduction rate (based on mass) is defined by the following equation (1): Reduction rate (%) = 100 × (mass of oxygen removed from raw material) / (mass of oxygen combined with iron, assuming all iron in the raw material before reduction is hematite) (1) For example, if the iron oxide before reduction is hematite, if all the iron ore after reduction is hematite, the reduction rate will be 0%, if all is magnetite, the reduction rate will be 11.1%, if all is wüstite (FeO), the reduction rate will be 33.3%, and if all is metallic iron, the reduction rate will be 100%. In other words, a reduction rate of 11.1% means that all the hematite has been reduced to magnetite, and a reduction rate of 60% means that metallic iron, wüstite, and magnetite are mixed together. The reduction rate of iron ore can be adjusted, for example, by changing the carbonization temperature, carbonization time, and the particle size ratio and mass ratio described above.

[0025] When the raw iron ore is an iron ore other than hematite (such as magnetite) or an iron ore containing iron ore other than hematite, it is sufficient that magnetite or iron ore having a higher degree of reduction than magnetite is obtained by the dry distillation step 4. In other words, it is sufficient that the iron ore is reduced to iron ore corresponding to the predetermined reduction rate (11% or more and 70% or less) based on the above-mentioned hematite.

[0026] The carbonization temperature (heating temperature) in the carbonization step 4 can be 700°C or higher and 900°C or lower. If the carbonization temperature is lower than 700°C, the thermal decomposition of the biomass does not proceed sufficiently, and the volatile content in the biomass char may not reach a value suitable for sintering in the sintering step 10 (approximately 10% by mass or less). Furthermore, the reduction of the iron ore may not proceed sufficiently. If the carbonization temperature exceeds 900°C, this may increase the amount of fuel required in the carbonization step 4. Furthermore, problems such as sticking (adhesion) of the iron ore may occur.

[0027] In the carbonization step 4, it is preferable to keep the volatile content of the biomass charcoal to 10% or less by mass, as mentioned above. If the volatile content is too high, substances derived from the volatile content may escape from the biomass charcoal into the exhaust gas during the sintering step and adhere to the electrostatic precipitator as oil.

[0028] Carbonization step 4 can be performed using various heating devices and systems. Examples of heating devices include, but are not limited to, a box furnace (batch furnace), an externally heated rotary kiln, an internal combustion rotary kiln, a shaft furnace, and a fluidized bed. Any type of heating device may be used. Carbonization step 4 may also be performed by mixing iron ore with the raw material of an existing biomass carbonization facility.

[0029] Next, in the sintering step 10, sintered ore is produced using the mixed dry distillate produced in the dry distillation step 4. The sintering step 10 can be carried out in an appropriate manner using a sintering machine. For example, the mixed dry distillate, untreated iron ore, and coke (coke powder) can be blended in an appropriate mass ratio, and the mixture is humidified and granulated in a mixer to produce a sinter raw material. Auxiliary materials such as limestone may be added to the sinter raw material. The granulated sinter raw material can then be loaded into a sintering machine using a hopper or drum feeder and sintered. The sintering machine is not particularly limited, but a Dwight Lloyd sintering machine, for example, can be used. The firing conditions in the sintering machine are not particularly limited, and the sintering can be carried out under appropriate conditions.

[0030] According to the present embodiment described above, a suitable method for producing sintered ore using biomass as a carbonaceous material for sintering can be provided. Specifically, by producing sintered ore using a mixed dry distillate containing biomass carbide and reduced ore according to the present embodiment, the productivity (production rate) of sintered ore is improved compared to when biomass carbide is used alone as a carbonaceous material for sintering (rather than in the form of a mixture). Furthermore, the amount of coke fines used can be reduced compared to when biomass carbide is used alone as a carbonaceous material for sintering, rather than as a mixed dry distillate. Therefore, the method of the present embodiment can further reduce CO2 emissions.

[0031] (Second embodiment) A second embodiment will be described. FIG. 2 is a diagram illustrating the flow of the method for producing sintered ore according to this embodiment. The method for producing sintered ore according to this embodiment uses biomass and iron ore as raw materials, as in the first embodiment, and includes a biomass particle size adjustment step 1, an iron ore particle size adjustment step 2, a blending step 3, a carbonization step 4, a separation step 5, a consolidation step 6, and a sintering step 10. This method differs from the first embodiment in that it further includes a separation step 5 and a consolidation step 6. In the separation step 5, the carbonized mixture is separated into reduced ore and biomass carbide. In the consolidation step 6, the biomass carbide is compressed and consolidated (high density). The production method according to this embodiment will be specifically described below. Explanations of parts common to the first embodiment will be omitted.

[0032] The particle size adjustment step 1, particle size adjustment step 2, blending step 3, and carbonization step 4 are the same as those in the first embodiment. However, when magnetic separation is used in the separation step 5 described later, it is preferable to perform each step so that the reduction rate of the iron ore after the carbonization step 4 is equal to or higher than the reduction rate that allows magnetic separation. Specifically, when the raw iron ore is hematite, it is preferable to set the reduction rate of the iron ore (reduced ore) after the carbonization step 4 to 11% or higher. As described above, if the reduction rate is 11% or higher, the hematite in the iron ore is reduced to magnetite, making separation using magnetic separation possible. As described above, the upper limit of the reduction rate may be 70% or lower. Therefore, it is preferable to perform each step so that the reduction rate of the iron ore after the carbonization step 4 is 11% or higher and 70% or lower. To achieve a reduction rate of 11% or higher, the top sizes of the biomass and iron ore supplied to the blending step 3, the particle size ratio of the top sizes of both, and the carbonization temperature in the carbonization step 4 can be set within the ranges described in the first embodiment. The reduction rate can also be adjusted by adjusting the carbonization time. When the raw iron ore is an iron ore other than hematite, it is sufficient that the carbonization step 4 produces iron ore with a reduction rate equal to or higher than that of magnetite.

[0033] In the separation step 5, the mixed dry distillate produced in the dry distillation step 4 is separated into biomass carbide 50 and reduced ore 51. The separation method (separation device) is not particularly limited, and an appropriate method (device) can be used. For example, magnetic separation, gravity separation, and flotation separation can be used as the separation method. In the case of magnetic separation, a magnetic separation device can be used. The type of magnetic separation device is not particularly limited, and a magnetic separation device capable of separating magnetite ore can be used.

[0034] Next, in the consolidation step 6, the separated biomass carbide 50 is compressed to produce a biomass carbide with a higher density (hereinafter also referred to as "consolidated biomass carbide"). The consolidation step 6 in this embodiment can be composed of a compression step 7, a pulverization step 8, and a sizing step 9. The consolidation biomass carbide 91 obtained in these steps is a consolidated particulate biomass carbide produced by pulverizing the compressed molded product. The consolidation biomass carbide 91 produced in the consolidation step 6 and the reduced ore 51 separated in the separation step 5 are blended again to produce a sintering raw material, and sintered ore is produced in the sintering step 10. The consolidation step 6 will be described in detail below.

[0035] First, in the compression step 7, the separated biomass charcoal 50 is compression-molded to produce a compression-molded product. The compression molding method (apparatus) is not particularly limited, and any method capable of applying pressure to biomass charcoal to produce a compression-molded product may be used. For example, a roller-type (ring die type, flat die type) compression molding machine or a screw-type extrusion molding machine may be used as a compression molding machine to produce a compression-molded product. Alternatively, a roll press method using a roll rotation compression molding machine or a tableting method using a biaxial compression molding machine may also be used. When compressing the biomass charcoal using these methods, a binder may be used, or water may be used together with the binder. Examples of binders that can be used include cornstarch (starch), bentonite, coal tar, biomass tar, petroleum pitch, and cement. Prior to the compression step 7, the biomass charcoal 50 may be pulverized in a pulverizer, and the pulverized biomass charcoal may be used for compression molding.

[0036] Next, in the pulverization step 8, the compression molded product of biomass carbide produced in the compression step 7 is pulverized to obtain a pulverized product. The pulverization method (apparatus) is not particularly limited, but for example, a rod mill, hammer crusher, roll crusher, super sander, jaw crusher, or fret mill can be used for pulverization. In the pulverization step 8, the compression molded product is pulverized to approximately 10 mm or less.

[0037] Next, in the sizing process 9, the particle size of the pulverized material produced in the pulverization process 8 is adjusted. In the sizing process 9, the particle size of the pulverized material is adjusted to a pulverized material with a top size of 7 mm or less. The sizing process 9 produces particulate consolidated biomass carbide 91 with a particle size adjusted to a top size of 7 mm or less. The consolidated biomass carbide 91 is supplied to the sintering process 10. This pulverized material with a top size of 7 mm or less can be produced by sieving the material through a sieve with openings of 7 mm or less and collecting the pulverized material that falls below the sieve. If the top size exceeds 7 mm, the biomass carbide may be unevenly distributed in the sintering process 10. The uneven distribution of the biomass carbide may lead to a decrease in the yield in the sintering process 10. The coarse pulverized material 92 that remains on the sieve in the sizing process 9 can be returned to the pulverization process 8.

[0038] In this sizing step 9, the particle size of the compacted biomass charcoal can be made even more uniform than with the method described above. Specifically, the pulverized material produced in the pulverization step 8 can be sized to a particle size of 1 mm to 5 mm. Specifically, by using a 1 mm sieve and a 5 mm sieve and collecting the material that falls below the 5 mm sieve and above the 1 mm sieve, a pulverized material with a particle size of 1 mm to 5 mm can be obtained. Furthermore, the coarse pulverized material 92 that falls above the 5 mm sieve (particle size greater than 5 mm) can be returned to the pulverization step 8 and pulverized again. Similarly, the fine pulverized material 93 that falls below the 1 mm sieve (particle size less than 1 mm) can be returned to the compression step 7 and compressed again.

[0039] In the consolidation step 6, the apparent density of the consolidated biomass charcoal 91 is 0.6 g / cm 3 It is preferable to set the density to 0.6 g / cm or more. 3If the density is less than this, the combustion rate during the sintering process will be too high, which may result in a decrease in the production yield of sintered ore. Apparent density is a value (bulk density) measured by the bead volume displacement method using a density measurement device (Micromeritics / GeоPyc). The bead volume displacement method, adopted by Micromeritics, is a volume displacement method using DryFlo (pseudo-fluid), a highly fluid bead. Specifically, the volume of the beads placed in the sample chamber alone is first measured, and then a sample is placed on the bead layer in the sample chamber and the volume is measured. The difference between the two volumes is used to calculate the volume of the measured sample, including pores and cavities. Apparent density is the mass of the measured sample divided by the calculated volume.

[0040] In the sintering step 10, sintered ore is produced using the reduced ore 51 separated in the separation step 5 and the consolidated biomass carbide 91 produced in the consolidation step 6 (from the compression step 7 to the sieving step 9). Specifically, the reduced ore 51, the consolidated biomass carbide 91, untreated iron ore, and coke (coke fines) are blended in an appropriate mass ratio. As in the first embodiment, the blended raw materials are subjected to humidity control and granulation in a mixer to produce a sintered raw material. Auxiliary materials such as limestone may be added to the sintered raw material. The granulated sintered raw material can be charged into a sintering machine and sintered. Sintering in the sintering machine can also be performed in the same manner as in the first embodiment.

[0041] The biomass carbide 50 and reduced ore 51 separated in the separation step 5 can also be used for purposes other than sinter production. For example, the biomass carbide can be used as a blast furnace (PCI) feedstock or a power generation (boiler) fuel. The reduced ore can be used as a blast furnace feedstock or a carbon-containing agglomerate feedstock.

[0042] According to the method of the present embodiment, after producing a mixed carbonized product by carbonizing iron ore and biomass, the biomass carbide is separated and consolidated, and then mixed with reduced ore again to be used as a sintering raw material, thereby further improving the productivity (production rate) of sintered ore. In addition, this method is preferable because it allows for a further reduction in the amount of coke fines used compared to when biomass carbide produced by carbonizing only the biomass carbide, rather than the mixed carbonized product, is consolidated and used as a carbonaceous material for sintering. [Example]

[0043] The present embodiment will be further described with reference to examples.

[0044] (Dry distillation test) A test was conducted to actually carry out the carbonization step 4 in the sinter ore manufacturing method of this embodiment to produce a mixed carbonized product. The test was conducted by carbonizing (heating) a mixture of biomass and iron ore in a small coke manufacturing test furnace (EREMA furnace).

[0045] ·Raw materials Cedar chips were used as biomass. The moisture content, proximate analysis, and elemental analysis values ​​of the cedar chips used are shown in Table 1. Robe River ore was used as the iron ore. The chemical composition of the iron ore is shown in Table 2. In Table 2, CW is water of crystallization and LOI is loss on ignition.

[0046] [Table 1]

[0047] [Table 2]

[0048] Testing Method The cedar chips and Robe River ore were each adjusted to a predetermined top size particle size. The size-adjusted cedar chips and Robe River ore were mixed in a predetermined mass ratio and charged into a small coke production test furnace (Erema furnace). The temperature of the test furnace was raised from room temperature to a predetermined temperature at a rate of 10°C / min up to a predetermined carbonization temperature, and then carbonized by holding at that carbonization temperature for 3 hours to obtain a mixed carbonized product. The above test conditions (particle size (top size) and particle size ratio of the raw materials subjected to carbonization, mass and mass ratio, and carbonization temperature) for each test example (Examples 1 to 5 and Comparative Examples 1 to 3) are shown in Table 3.

[0049] Evaluation of mixed distillate The mixed dry distillate from each test example was separated into reduced ore and cedar carbide (biomass carbide) by magnetic separation. For samples where magnetic separation was difficult, the reduced ore and biomass carbide were visually collected. The reduction ratio of the reduced ore (iron ore) after dry distillation was then determined. The reduction ratio was calculated using equation (1) described in the description of the embodiment. The reduction ratio was determined by calculating the amount of oxygen bound to iron from the total iron (T-Fe) content (JIS-M8212), iron oxide II (FeO) content (JIS-M8213), and metallic iron (M-Fe) content (JIS-M8213 explanation method) in the reduced ore, which were determined by analysis, and the iron oxide III (FeO) content, which was calculated by calculation. The residual volatile content of the cedar carbide was also measured using the method specified in JIS-M8812. Table 3 shows the reduction rate (mass%) of the iron ore and the volatile content (mass%) of the cedar carbide.

[0050] [Table 3]

[0051] As can be seen from the results shown in Table 3, reduced ores with sufficient reduction rates were obtained in all of Examples 1 to 5. Furthermore, the volatile content of the cedar carbide biomass was also 10% or less in all cases, meaning that biomass carbide with a volatile content suitable for use as carbon material in the sintering process was obtained.

[0052] On the other hand, in Comparative Example 1, where the carbonization temperature in the carbonization process was 600°C, separation by magnetic separation was difficult, so the reduced ore and cedar carbide were visually collected and analyzed. The cedar carbide in Comparative Example 1 had a volatile content of over 10%, at a level that required restrictions on the amount used when used as carbon material in the sintering process. The reduction rate of the reduced ore was low at 6.6%. Magnetic separation was also difficult in Comparative Example 2, where the mass ratio was less than 0.2. Analysis of the visually collected sample showed that the reduction rate of the iron ore was low at 9.5%. Magnetic separation was also difficult in Comparative Example 3, where the particle size ratio was less than 0.3. Analysis of the visually collected sample showed that the reduction rate of the reduced ore was low at 7.7%.

[0053] (Sintering test) A sintering test was carried out to produce sintered ore using the dry distillate mixture produced by the method described in this embodiment. The productivity and yield were evaluated by the sintering test.

[0054] Sintering raw materials In the test example of Example 6, the mixed dry distillate was used as a sintering raw material without being compacted, and was prepared as follows. First, the mixed dry distillate (reduced ore and cedar carbide) prepared in Example 2 above and coke were blended in a predetermined mass ratio and charged into a drum mixer (diameter 380 mm, rotation speed 32 rpm). The mixture was mixed in the drum mixer for 1 minute, and then 7% by mass (excluding figures) of water was added to the raw materials. The mixer was rotated for another 4 minutes to granulate the mixture, which was used as the sintering raw material of Example 6. The top size of the cedar carbide in the mixed dry distillate was measured using a test sieve for the cedar carbide separated by magnetic separation from the dry distillation mixture of Example 2.

[0055] Examples 7 and 8 are test examples (Examples 7 and 8) in which the separation step 5 and the consolidation step 6 were performed on the mixed dry distillate of Example 2. Specifically, in Example 7, the mixed dry distillate was first separated into reduced ore and cedar carbide (biomass carbide) using a magnetic separator. Next, the cedar carbide was crushed to 5 mm or less using a crusher, and a binder (cornstarch) and water were added and kneaded in a mixer. The kneaded cedar carbide was placed in a ring die extrusion molding machine and compression-molded. The molded product was dried in a dryer to produce a compression-molded cedar carbide product with a diameter of 10 mm and a length of 10 mm. This compression-molded product was placed in a tumbler for a rotational strength test and crushed by 30 rotations. Next, the crushed product was sieved to a particle size of 7 mm. The sized pulverized material, reduced ore separated from the mixed dry distillate, and coke fines were blended in a predetermined mass ratio, mixed and granulated in the same manner as in Example 6, to prepare the sinter raw material for Example 7. In Example 8, sieves with 1 mm and 5 mm openings were used in the sizing step, and the pulverized material obtained by collecting the particles that fell under the 5 mm sieve and over the 1 mm sieve (1-5 mm pulverized material) was used. The other conditions were the same as in Example 7.

[0056] Comparative Example 4 is an example in which sintered ore was produced using a sintering raw material in which Robe River ore and coke fines shown in Table 2 were blended in a predetermined mass ratio. Comparative Example 5 is an example in which a portion of the coke in Comparative Example 4 was replaced with cedar carbide. Specifically, cedar carbide separated by magnetic separation from the mixed dry distillate of Example 2, Robe River ore, and coke fines were blended in a predetermined mass ratio and granulated to produce sintered ore. In other words, this is an example in which sintered ore was produced by combining untreated iron ore and only the biomass carbide from the mixed dry distillate. The above test conditions for each test example (raw material blending amount (mass), apparent density of cedar carbide, particle size (top size, 1-5 mm crushed material ratio (mass%)) are shown in Table 3.

[0057] The apparent density of the cedar charcoal was measured by the bead volume displacement method using a density measuring device (Micromeritics / GeOPyc) as shown in the embodiment. The cedar charcoal sample was placed in a layer of DryFlO (pseudo-fluid), and the volume (apparent volume) of the sample, including the pores and cavities, was measured. The apparent density was then calculated from the apparent volume and the mass of the sample. For Example 6 and Comparative Example 5, the apparent densities were measured for cedar charcoal separated by magnetic separation from the dry distillation mixture of Example 2 used in the sintering test. For Examples 7 and 8, the apparent densities were measured for the pulverized material (consolidated biomass charcoal) after sieving and before sintering.

[0058] Sintering test conditions The raw materials for each test example were sintered using a sintering pot tester, a smaller version of the sintering machine. A sintering pot with a diameter of 100 mm and a bed thickness of 445 mm was used. Air was supplied at a flow rate of 0.08 Nm. 3 The firing was carried out with an air flow rate of 1 / min. For each test example, the production rate and yield were calculated and evaluated as follows. The calculated production rate and yield are shown in Table 4.

[0059] Production rate The production rate is 1m2 of firing area. 2 The production rate P [t / d / m 2 ] can be calculated using the following formula (2).

[0060] P = Ms / (S × ts) × 60 × 24 (2) Ms [t] is the mass of the sintered ore on the sieve obtained by dropping the sinter cake obtained after sintering from a height of 2 m four times and then sieving it through a sieve with 5 mm openings. S [m 2 ] is the effective area of ​​the sintering pot in a plan view, and ts [min] is the sintering time. The sintering time was measured by measuring the temperature of the exhaust gas discharged from the bottom of the sintering pot, and was defined as the time from ignition to the point at which this temperature reached its peak.

[0061] Yield The mass percentage of the sinter particles (+5 mm particles) remaining on the sieve with 5 mm openings in the above productivity test relative to the total mass of the sinter cake was determined as the yield in this test.

[0062] [Table 4]

[0063] In Example 6, the productivity was significantly higher than in Comparative Example 4, in which sintered ore was produced using ordinary iron ore and coke fines. Normally, the use of charcoal results in a lower yield, but due to the effect of the reduced ore contained in the sinter raw material as a mixed carbonized product, the yield was comparable to that of Comparative Example 4, which used a conventional method. Furthermore, in Example 6, the same biomass carbide was used, but in combination with untreated iron ore instead of reduced ore, both the productivity and yield were significantly higher than in Comparative Example 5.

[0064] In Examples 7 and 8, in which a compaction process was carried out, the productivity and yield were further improved compared to Example 6. In Example 8, in which the particle size was sized to a narrower particle size range (1-5 mm) than in Example 7 (top size 7 mm) in the sizing process after compression in the compaction process, it was confirmed that the productivity and yield were further improved. Furthermore, in all Examples, the amount of NOx generated was significantly reduced compared to Comparative Examples 4 and 5.

Claims

1. a particle size adjusting step of adjusting the particle sizes of the biomass and the iron ore to predetermined particle sizes, respectively; a dry distillation step of dry distilling the mixture of the biomass and the iron ore whose particle size has been adjusted in the particle size adjustment step to produce a mixed dry distillate which is a mixture of biomass carbide and reduced ore which is reduced iron ore; a sintering step of producing sintered ore using the mixed dry distillate produced in the dry distillation step, The predetermined particle size of the biomass adjusted in the particle size adjustment step is 3 mm or more and 7 mm or less in top size, The predetermined particle size of the iron ore is 7 mm or more and 10 mm or less in top size, a particle size ratio of the biomass to the top size of the iron ore (biomass top size / iron ore top size) of 0.3 or more; a mass ratio of the biomass to the iron ore in the mixture (mass of biomass / mass of iron ore) of 0.2 or more; The dry distillation temperature in the dry distillation step is 700°C or higher and 900°C or lower, The method for producing sintered ore, wherein the reduced ore produced in the dry distillation step has a reduction rate of 70% or less based on hematite.

2. a separation step of separating the mixed dry distillate into the biomass charcoal and the reduced ore by magnetic separation, gravity separation, or flotation separation; and a consolidation step of compressing the biomass charcoal separated in the separation step to produce a consolidated biomass charcoal. In the sintering step, sintered ore is produced using the compacted biomass carbide and the reduced ore separated in the separation step, The reduction rate of the reduced ore produced in the dry distillation step is 11% or more based on hematite, The densified biomass charcoal used in the sintering step has an apparent density of 0.6 g / cm ３ 2. The method for producing sintered ore according to claim 1, wherein the top size is 7 mm or less.

3. The consolidation step a compression step of compressing and molding the biomass carbonized material to produce a compressed product; a grinding step of grinding the compressed product; 3. The method for producing sintered ore according to claim 2, further comprising a sizing step of sizing the pulverized material produced in the pulverization step.

4. 4. The method for producing sintered ore according to claim 3, wherein in the sieving step, the crushed material that falls under the 5 mm sieve and over the 1 mm sieve is used as the consolidated biomass carbide in the sintering step.

5. In the sizing step, The pulverized material on the 5 mm sieve is returned to the pulverization step.

5. The method for producing sintered ore according to claim 4, wherein the crushed material that falls below the 1 mm sieve is returned to the compression step.

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