JP6001487B2 - Method for producing sintered ore for iron making - Google Patents

Description

  The present invention relates to a method for producing a sintered ore for iron making.

Conventionally, not only iron ore mined but also sintered ore obtained by firing powder ore has been used as a blast furnace raw material. Various techniques for producing such sintered ore have been developed as shown in Patent Documents 1 to 7 below.
In Patent Document 1, in a method for producing a sintered ore by sintering a sintered raw material containing various ores and auxiliary materials, 50% or more of the ore to be mixed with the sintered raw material is pisolite ore, and other ores Ore containing 2% or more and less than 5% of SiO ₂ and 3% or more and less than 6% of bound water, and pellet feed or ore containing SiO ₂ of less than 2%. Patent Document 1 discloses a composition as a goethite (Fe ₂ O ₃ · 2H ₂ O), but the composition of goethite is Fe ₂ O ₃ · H ₂ O, which is erroneous. It is.

In Patent Document 2, in a sintered ore production method in which 30 to 50% of iron ore raw material is pisolite ore, 70 to 80% of the whole pisolite ore, iron ore raw material excluding pisolite ore, limestone, serpentine and coke are used. The remaining 20-30% of pisolite ore is mixed and charged into a sintering machine for sintering.
In addition to Patent Documents 1 and 2, there are methods shown in Patent Documents 3 to 5 as methods for producing sintered ore. Although not in the steel field, Patent Documents 6 and 7 disclose techniques for producing color pigments used in cosmetics and paints using iron hydroxide as a raw material.

  Moreover, in performing sintering, there exist some which are shown to patent documents 8-10 as a technique using gaseous fuel or liquid fuel. In performing sintering, there are those shown in Patent Documents 11 to 14 that use exhaust gas, and those shown in Patent Documents 15 and 16 that apply a load to the raw material.

Japanese Patent Laid-Open No. 10-245638 Japanese Patent Laid-Open No. 08-176688 JP 05-098359 A JP 05-105969 A Japanese Patent Laid-Open No. 04-080327 JP 2005-255500 A Japanese Patent Laid-Open No. 10-204318 JP 2009-228133 A JP 2010-106342 A JP 2012-026001 A JP 2001-241863 A Japanese Patent Laid-Open No. 08-260062 JP 2002-121620 A JP 2010-126774 A JP 09-020934 A Japanese Patent Laid-Open No. 60-234927

Patent Documents 1 and 2 are techniques for producing sintered ore using a raw material having a valence n of 1.0 or less when iron hydroxide is represented by Fe ₂ O ₃ .nH ₂ O. That is, as shown in the techniques of Patent Documents 1 and 2, in the field of producing sintered ore, the idea of producing sintered ore using iron hydroxide having a valence n exceeding 1.0 is There was nothing at all. In addition, even if other patent documents 3-5 are seen, there is no technique which manufactures a sintered ore using the iron hydroxide whose valence n exceeds 1.0 similarly. In addition, although the technique of using iron hydroxide whose valence n exceeds 1.0 is shown in Patent Documents 6 and 7, these techniques are completely different from the technique of manufacturing sintered ore for iron making. Is.

Moreover, in performing sintering, although it is disclosed in Patent Documents 8 to 16 as applying a load to gaseous fuel, liquid fuel, exhaust gas, or raw material, sintering is not performed using iron hydroxide. Even if this technique is used, the fact is that it is impossible to produce sintered ore using iron hydroxide having a valence n exceeding 1.0.
The present invention has been made in view of the above-mentioned problems, and is an inferior iron ore (iron hydroxide with a valence n exceeding 1.0, in other words, an ultrahigh crystal water-containing ore that could not be used conventionally. It is an object of the present invention to provide a method for producing a sintered ore for iron making that can be used as a raw material for iron making such as a blast furnace.

In order to achieve the above-described object, the present invention takes the following technical means.
In the method for producing a sintered ore for iron making according to the present invention, Fe ₂ O ₃ .nH ₂ O has an iron hydroxide of n exceeding 1.0 and 4.0 or less, a CaO source, and a CaO / Fe ₂ O _3. The mixture is mixed so that the molar ratio is more than 0.5 and less than 2.0, and the mixed mixture is charged at 2% by mass or more and less than 30% by mass with respect to other sintering raw materials and sintered. In the length direction of the sintering machine that performs sintering, when the sintering section starting from the ignition furnace and starting from the discharge portion is defined as 100%, a combustible gas and / or a combustible liquid is used during sintering. Is supplied while it becomes 10% to 90% of the sintering section.

Preferably, during the sintering, exhaust gas is recovered from the sintering machine between 60% and 100% of the sintering section, and the recovered exhaust gas is supplied while it becomes 10% to 90% of the sintering section. Good.
Other means of the method for producing the sintered ore for iron making according to the present invention is as follows: Fe ₂ O ₃ .nH ₂ O has an iron hydroxide of n exceeding 1.0 and 4.0 or less, a CaO source, and a CaO / The mixture was mixed so that the molar ratio of Fe ₂ O ₃ was more than 0.5 and less than 2.0, and the mixed mixture was charged in an amount of 2% by mass or more and less than 30% by mass with respect to other sintered raw materials. In the length direction of the sintering machine for sintering, when the sintering section starting from the ignition furnace and starting from the discharge section is defined as 100%, during sintering, the sintering section The exhaust gas is recovered from the sintering machine between 60% and 100%, and the recovered exhaust gas is supplied while it becomes 10% to 90% of the sintering section.

Preferably, at the time of sintering, the raw material containing the mixture and the other sintered raw materials is compacted by applying a load on the exit side of the ignition furnace of the sintering machine.
Other means of the method for producing the sintered ore for iron making according to the present invention is as follows: Fe ₂ O ₃ .nH ₂ O has an iron hydroxide of n exceeding 1.0 and 4.0 or less, a CaO source, and a CaO / The mixture was mixed so that the molar ratio of Fe ₂ O ₃ was more than 0.5 and less than 2.0, and the mixed mixture was charged in an amount of 2% by mass or more and less than 30% by mass with respect to other sintered raw materials. At the time of sintering, the raw material containing the mixture and the other sintered raw materials is weighted and consolidated on the exit side of the ignition furnace of the sintering machine.

  According to the present invention, inferior iron ore (iron hydroxide with a valence n exceeding 1.0, in other words, ultra-high crystal water-containing ore) that could not be used conventionally is used as a raw material for iron making such as a blast furnace. can do.

It is a figure which shows the whole sintering machine. It is a figure which shows a heat pattern when performing sintering. It is a relationship figure of n of iron hydroxide when a production rate is 2.3-2.5 (t / m < ² > / h), and a yield. It is a related figure of n of iron hydroxide when a production rate is 1.7-1.9 (t / m < ² > / h), and a yield. It is a _CaO-Fe 2 _{O 3} binary phase diagram. It is the figure which showed the combined state of the mixture before and behind sintering (before and after baking), and a sintering raw material. It is a related figure of the compounding quantity and yield of a mixture in case a production rate is 2.3-2.5 (t / m < ² > / h). It is a related figure of the compounding quantity and yield of a mixture in case a production rate is 1.7-1.9 (t / m < ² > / h). It is the figure which showed the sintering area | region and combustion area | region (combustion zone) in sintering. It is a change figure of a combustion zone at the time of supply of flammable gas and flammable liquid. It is a figure which shows the heat pattern at the time of supplying combustible gas and a combustible liquid. It is a general view of the sintering machine which supplies a combustible gas and a combustible liquid. It is a figure which shows the heat pattern at the time of supplying waste gas. It is a general view of the sintering machine which supplies exhaust gas. It is a figure which shows the change of the sintering raw material when compacting. It is a figure which shows the relationship between the pressure when a pressure is applied to a sintering raw material layer, and a yield. 1 is an overall view of a sintering machine that performs consolidation. FIG. It is a general view of the sintering pot for a test. It is the figure which showed the relationship between the calorie | heat amount and a yield in an Example.

The manufacturing method of the iron ore sintered ore of the present invention will be described.
Conventionally, in a blast furnace, an iron ore (or ore) containing iron ore is introduced from the upper part of the furnace body and hot air is blown from the lower part. Pig iron is produced by a series of reactions such as reduction and dissolution. This blast furnace is a counter-current reactor that continuously performs heat exchange / reduction reactions with the gas ascending in the furnace. For this reason, it is important that the charge to be charged into the blast furnace, particularly the sintered ore, has a dust resistance (strength) that does not impede gas passage in the furnace and good reducibility.

Therefore, in the manufacturing process of sintered ore, calcium ferrite (hereinafter referred to as CF) is synthesized as much as possible, and by forming a connective structure due to the CF-based melt between the particles of the sintering raw material, strength and It becomes possible to produce a sintered ore excellent in reducibility.
In the process upstream of the blast furnace (sintering pretreatment process in the iron making process), for example, a sintered ore is manufactured by using a droidoid type sintering machine in which a pallet is configured in an endless belt shape. First, the sintering machine will be described in detail.

  As shown in FIG. 1, in the sintering machine 10, rollers 11 are arranged on the supply side of the sintering raw material and on the discharge side of the sintered ore. The sintering machine 10 has a plurality of pallets, and the pallets are connected to each other to form an endless belt. Each pallet can be moved from the supply side to the discharge side by rollers 11 and 11. On the supply side of the sintering raw material, a raw material supply device 13 for supplying the sintering raw material is provided. On the downstream side (exhaust side) of the raw material supply device 13, the sintering raw material is ignited from above. An ignition furnace 14 is provided. The sintering machine 10 is provided with a plurality of wind boxes 15 along the length direction of the sintering machine 10. The exhaust gas is collected by an exhaust fan communicating with the wind box 15.

  When manufacturing sintered ore, first, sintered raw materials consisting of ore, solid fuel (coke powder, etc.), auxiliary materials, etc. are moved to the pallet moving from the sintered raw material supply side to the sintered ore discharge side. Are sequentially supplied and filled to form a sintered raw material layer. Then, in the ignition furnace, by igniting the upper part of the sintering raw material layer and allowing air to pass downward, the combustion proceeds toward the lower part of the sintering raw material layer, and until the exhaust raw material side, This is done by completing the firing.

Here, looking at the sintering process, the sintered raw material charged on the pallet contains solid fuel (coke powder) called a coagulant. When the combustion gas is further sucked by the blower, the frame accompanying the combustion of the solid fuel descends in the sintering material layer, and the sintering material is heated and heated around and below the frame. The part where the frame has already passed is continuously cooled by the gas supplied from above. In the sintering raw material layer, the heat pattern at a certain fixed point from when it is charged on the pallet until it is discharged is as shown in FIG.

On the other hand, the CaO source contained in the sintering raw material is heated and heated during the sintering, and when the temperature exceeds a certain temperature, the synthesis of CF is started by the solid phase reaction between the iron ore and the CaO source, and reaches the melting point of CF. Then, a part of the synthesized CF is eluted as a melt between the particles of the sintering raw material. In the subsequent cooling process, this solidifies to form a connective structure that firmly bonds the sintered raw materials.
Since the connective tissue is formed by solidifying what is eluted as a melt, if the heat pattern is the same, the time during which connective tissue can be formed is the time when the CF that has already been synthesized by solid-phase reaction is used. It is thought to be the time from melting to solidification. Conventionally, an approach and a technique for improving the heat pattern and extending the formation time of a suitable connective tissue have been reported. However, these prior arts involve major modifications of equipment and processes.

In the present invention, iron hydroxide having a structure of Fe ₂ O ₃ .nH ₂ O is used as a part of the sintering raw material, and the synthesis (generation of CF) is performed by mixing this iron hydroxide and a CaO source. ). When sintering is performed using iron hydroxide, the temperature is raised by heating as the sintering raw material layer as shown in FIG. 2 rises, and thermal decomposition starts at around 300 ° C. At this time, iron hydroxide has a specific surface area and a surface shape that is very active. When such a surface-shaped iron hydroxide is mixed with a CaO source, the synthesis of CF by a solid-phase reaction is started at a lower temperature than before.

  That is, even if sintering is performed with the same heat pattern as in the past, by mixing iron hydroxide ore and CaO source as in the present invention and proceeding with sintering, solid phase reaction can be performed from an early stage. CF can be synthesized, and the CF time by solid phase reaction can be lengthened. That is, as shown in FIG. 2, in the past, for example, CF synthesis was started at arrow B in FIG. 2, but in the present invention, CF synthesis can be started at an early stage of arrow C. .

As a result, when the CF melting start temperature is reached (when entering the section A in FIG. 2), a larger amount of CF melt than before is eluted, and when cooling, a larger amount of CF connective tissue is formed than before. Can be formed. The section A is an example of a connective tissue formation section (time from elution of CF melt to solidification).
As described above, it is considered that a large amount of CF can be generated by mixing the iron hydroxide of Fe ₂ O ₃ .nH ₂ O and the CaO source to accelerate the synthesis of CF, but promote the synthesis of CF. In order to achieve this, it was considered advantageous to use particles having a large reaction interfacial area and high surface reactivity, and verified what kind of iron hydroxide was suitable.

Iron hydroxide that is Fe ₂ O ₃ .H ₂ O (n = 1) is called goethite, and when this goethite is used, as shown in FIGS. In addition, it is not possible to use a goethite with a low charge yield and substantially n = 1. Further, it is considered that n = 0 to 1 is composed of n = 1 goethite and Fe ₂ O ₃ (hematite) containing no bound water. Even if it is, the yield of the charge is not improved as in the game site.

  On the other hand, when a hydroxide having n of more than 1 (n> 1) is used for sintering, a large amount of heat is required for decomposition of the bound water in the process of firing, and extra firing energy is required. It has been considered undesirable to use iron hydroxide for sintering. In other words, when iron hydroxide is used as part of the raw material constituting the sintered raw material particles, it is generated in the sintered ore raw material particles due to heat shortage due to the endothermic reaction accompanying the decomposition reaction of bound water and the release of water vapor during decomposition. Due to the cracking, the contact between the particles is insufficient, and further, since the CaO source for forming CF is not necessarily present in the vicinity of the iron hydroxide, in the solid state in the particles of the sintering raw material It has been thought that CF synthesis does not proceed efficiently, the strength of the sintered ore connective structure decreases, and the yield decreases. For this reason, as a matter of course, it has never been conceived so far to use iron hydroxide, which has a stronger effect of bonding water than when n exceeds 1.0, as a means for bonding sintered raw materials.

However, the inventors have continued to verify iron hydroxide whose n exceeds 1.0 without being caught by the conventional idea. As a result, it was found that when a hydroxide with n exceeding 1 (n> 1) was used for sintering, the yield of the charge could be improved as shown in FIGS. .
It should be noted that iron hydroxide (iron hydroxide or hydroxide ore) is expressed as Fe ₂ O ₃ .nH ₂ O is technical literature: “Steel production method, 3-1 raw material, Table 3.1 iron ore. No. 4, 163, Japan Iron and Steel Institute book, published on April 10, 1972, Maruzen Co., Ltd., and is well known among those skilled in the art. Also, in iron hydroxide, for example, as shown in "Lecture: Modern Metallurgy, Volume 1 Steel Smelting, Japan Metallurgy Society, Issue 1 pp. Pp. 98-99" In addition, it is known that the value of n does not exceed 4 mineralogically. The n of iron hydroxide is a coefficient expressing the amount of compound water, and can be determined by thermal analysis and chemical analysis. Specifically, the valence is the total iron number tFe (JIS M8212 total iron determination method), divalent iron (JIS M8213 divalent iron determination method), FeO and compound water (JIS M8211 compound water determination by chemical analysis). Method) and the amount of CW. The valence n is obtained by n = W / Hm × 2 (however, Hm = tFe / 55.85-FeO / 71.85, W = CW / 18).

Above, in the present _invention, it is possible to Fe ₂ O 3 · nH ₂ O n is the 4.0 or less iron hydroxide over 1.0, and a CaO source were mixed, to promote the formation of CF.
Now, the CaO sources mixed with the iron hydroxide described above are quick lime CaO, slaked lime Ca (OH) ₂ , and limestone CaCO ₃ . In mixing the iron hydroxide and the CaO source, any one or more of quick lime, slaked lime, and limestone may be used. Limestone and slaked lime decompose upon heating to produce CaO. Further, quick lime, slaked lime, and limestone may be mixed and used. In producing a sintered ore, JP 2004-315277 A discloses an example in which gypsum is used. However, in this method, it is necessary to remove Ca, which is an impurity, and desulfurization. Since a process is required, it is difficult to use industrially.

In summary, in the sintering pretreatment step, the mixture of Fe ₂ O ₃ .nH ₂ O in which iron hydroxide of n exceeding 1.0 and 4.0 or less and the CaO source are mixed and mixed at the time of sintering. And, this mixture is fired with another sintering raw material different from the mixture.
As described above, CF is synthesized by a solid phase reaction between iron hydroxide and a CaO source during heating and heating. In order to synthesize this CF without excess or deficiency, CaO- As shown in the Fe ₂ O ₃ binary system phase diagram, the range D including the lower limit temperature of the liquidus may be set. That is, when mixing the iron hydroxide and the CaO source, the molar ratio of CaO to Fe ₂ O ₃ (CaO / Fe ₂ O ₃ ) in the mixture is more than 0.5 and less than 2.0. Just do it.

  FIG. 6 shows the bonding state between the mixture before and after sintering (before and after firing) and the sintering raw material. As shown in FIG. 6A, before sintering, the mixture 1 and another sintered raw material (referred to as other raw material) 2 different from the mixture 1 exist in separate states. As shown in FIG. 6 (a), when sintering proceeds while the mixture 1 enters between the other raw materials 2 and 2 (between the particles of the sintered raw material), a large amount of CF ( CF solution) is eluted, and the eluted CF solution is assimilated with the other raw material 2, and after sintering, the other raw materials 2 are bonded to each other by a strong connective structure 3 as shown in FIG. 6B.

As described above, in order to firmly bond other raw materials to each other by the CF solution eluted from the mixture, in the present invention, the mixture is charged (mixed) in an amount of 2% by mass to less than 30% by mass with respect to the other raw materials. It is said.
As shown in FIGS. 7 and 8, when the blending amount of the mixture with respect to other raw materials is less than 2% by mass, a sufficient amount of connective structure cannot be formed in the sintered raw material layer, and the yield is not improved. . That is, if the mixture of the other raw materials is less mixed, the ratio of the mixture contained between the particles of the other raw materials is smaller than the entire sintered raw material layer, so that the strength of the entire sintered raw material layer can be improved. However, the yield could not be improved sufficiently.

When the blending amount of the mixture with respect to other raw materials is 2% by mass or more, the yield is rapidly improved. As the charging amount of the mixture is gradually increased from 2% by mass, the total amount of CF melt eluted from the mixture increases. Although a certain amount of CF melt acts as a connective structure and contributes to the bonding of other raw materials, the excess CF melt that did not work as a connective structure is located below the sintered raw material layer due to the downward ventilation during sintering. Although it moves, it solidifies in the middle of the sintering raw material layer (for example, in the vicinity of the middle lower layer portion), and there is a possibility that the suction of the combustion gas by the blower may be hindered. That is, when the CF melt moving by the downward air flow is excessive, the gas passing through the sintering raw material layer drifts, increasing the generation rate of the so-called non-uniform sintered structure called burn unevenness, and increasing the yield. May decrease.

As shown in FIGS. 7 and 8, when the blending amount of the mixture with respect to the other raw materials and the state of the yield are seen, the yield is improved when the blending amount of the mixture with respect to the other raw materials is 2% by weight or more, but 30% by weight. Above this, the yield decreased. Therefore, the mixture needs to be 2% by mass or more and less than 30% by mass with respect to other sintering raw materials.
Summarizing the above, in the present invention, n of Fe ₂ O ₃ .nH ₂ O exceeds 1.0 and is 4.0 or less, and the molar ratio of CaO / Fe ₂ O ₃ is 0.00. Mixing so that it exceeds 5 and less than 2.0, and charging the mixed mixture to 2 to 30% by mass with respect to other sintering raw materials to produce sintered ore, improving yield I am going to let you.

In order to promote the formation of CF, the formation of connective tissue, etc., in the present invention, when sintering the sintered ore with a sintering machine, the sintering is performed by the following methods (i) to (iii). To do. In the sintering, at least one method (i) to (iii) may be used.
(i) At the time of sintering, either flammable gas or flammable liquid, or both flammable gas and flammable liquid are supplied during 10% to 90% of the sintering section (combustion supply) Method).

(ii) During sintering, exhaust gas is recovered from the sintering machine between 60% and 100% of the sintering section, and the recovered exhaust gas is supplied while it becomes 10% to 90% of the sintering section ( Exhaust gas supply method).
(iii) At the time of sintering, on the exit side of the ignition furnace of the sintering machine, the raw material containing the mixture and other raw materials is applied with a load and consolidated (consolidation method).
In addition, as shown in FIG. 9, the sintering section refers to the longitudinal direction of the sintering machine (the sintering machine) with the exit side of the ignition furnace of the sintering machine as the starting point and the end point where the ore is discharged. It is the section of the machine length direction). In the sintering section, the starting point side is set to “0%” and the end point side is set to “100%”.

Hereinafter, (i) to (iii) will be described in order.
(i) Combustion Supply Method As the combustible gas, a gas composed of blast furnace gas, coke oven gas, city gas, natural gas, methane gas, ethane gas, propane gas, and other hydrocarbon compounds is used. As the flammable liquid, a liquid composed of alcohols, ethers, petroleums, and other hydrocarbon compounds is used.

  As shown in FIG. 9, when looking at the change in the combustion region of the sintering raw material, the fuel region gradually moves from the upper side to the lower side as it goes to the discharge side due to the influence of downward ventilation (blower). . On the other hand, the combustion region moves from the supply side of the sintering raw material to the discharge portion side as the pallet moves. Therefore, when sintering is performed, the combustion of the sintering raw material proceeds from the uppermost layer to the lowermost layer until the pallet reaches the discharge side from the supply side along the length direction of the sintering machine. The heat pattern at this time is as shown in FIG.

  As in the present invention, when a flammable gas or a flammable liquid is supplied to a sintering raw material (including a mixture and other raw materials) during sintering, the flammable gas or the flammable liquid moves by downward ventilation, and a combustion region Burns near (combustion zone). Thus, by supplying the combustible gas or the combustible liquid, as shown in FIG. 10, the width of the combustion zone is expanded as compared with the case where the combustible gas or the combustible liquid is not supplied, and at a predetermined fixed point. Can increase the time during which the temperature rises (high temperature holding time). Even when both the combustible gas and the combustible liquid are supplied to the sintering raw material, the same effect can be obtained and the high temperature holding time can be extended.

That is, by supplying either or both of the flammable gas and the flammable liquid at the time of sintering, as shown in FIG. 11, the heat pattern in the sintering is changed to a pattern having a long time for high temperature. be able to.
When the high temperature holding time in the fuel zone is extended, the reaction time of the mixture of iron hydroxide and CaO source can be extended, and the formation of connective tissue can be promoted. In other words, by increasing the high temperature holding time, it is possible to increase the time for synthesizing CF and the time for assimilating CF to other surrounding raw materials. Even when both the combustible gas and the combustible liquid are supplied to the sintering raw material, the same effect can be obtained and the high temperature holding time can be extended.

  In this way, during sintering, the formation of connective tissue can be promoted by supplying a combustible gas or a combustible liquid fuel from above, but the section less than 10% in the sintering section is an ignition furnace. Since it is immediately after igniting the upper part of the sintering raw material layer (temperature rise process), there is a risk of burning up if a combustion product is supplied in this section. On the other hand, in the section exceeding 90% in the sintering section, the combustion area reaches the lowermost layer, and even if the fuel is supplied, the synthesis of CF and the promotion of the formation of the connective structure cannot be promoted. The effect of extending the holding time cannot be expected.

For this reason, the section for supplying the combustibles (flammable gas and / or flammable liquid or both) is 10% or more and 90% or less of the sintering section. When supplying the combustion product during sintering, as shown in FIG. 12, the combustion product supply device 16 for supplying the combustion product is provided between 10% and 90% of the sintering section, and the combustion product is sintered. Supply toward the top.
(ii) Exhaust gas supply method
In (i), the combustion product was supplied during 10% to 90% of the sintering zone, and the temperature of the combustion zone was raised, but in (ii), a high temperature gas was supplied during sintering. I am going to do that. In the sintering section, at 60% to 100%, the combustion region is in a state of progressing from the middle layer to the lower layer, and high-temperature exhaust gas can be recovered. Therefore, the high-temperature gas recovered in 60% to 100% of the combustion region is supplied toward the sintering raw material from above.

As described above, even when high-temperature exhaust gas is supplied to the sintering raw material (including the mixture and other raw materials), the exhaust gas can be moved by the downward ventilation to increase the temperature of the sintering raw material layer. In other words, when exhaust gas is supplied, the heat pattern can be changed to a pattern that becomes entirely high as shown in FIG.
Also in the exhaust gas supply method, since the mixture of iron hydroxide and CaO source can be kept at a high temperature, the reaction time of the mixture of iron hydroxide and CaO source can be extended as in (i). , Can promote the formation of connective tissue.

  Even in the case of supplying high-temperature exhaust gas, if it is less than 10% of the sintering section, it is close to the ignition furnace 14 and is a section immediately after ignition. is there. Also, if it exceeds 90% of the fuel section, the combustion region has reached the lowest layer, so it is not possible to promote the synthesis of CF or the formation of connective tissue, and the effect of extending the high temperature holding time is I can't expect it.

  For this reason, the section for supplying high-temperature exhaust gas is also set to 10% or more and 90% or less of the sintering section. When supplying the exhaust gas during sintering, as shown in FIG. 14, an exhaust gas circulation device 18 for circulating the exhaust gas recovered from the wind box 15 side to the exhaust gas supply hood 17 is provided, and 60% to 100% of the sintering section Only the exhaust gas recovered in step 1 is supplied using an exhaust gas supply hood 17 installed in the range of 10% to 90% of the sintering section.

The method (ii) described above and the method (i) may be combined to supply the combustible gas, the combustible liquid, and the exhaust gas to the sintering raw material (including the mixture and other raw materials).
(iii) Consolidation method Unlike the above-mentioned (i) and (ii), the consolidation method consolidates the raw material (sintered raw material layer) from the outlet side of the ignition furnace to the downstream side by applying a load from above. doing. That is, a sintered raw material containing a mixture of iron hydroxide and a CaO source and another raw material is compacted by applying a load after leaving the ignition furnace.

As shown in FIG. 15, in a state where the compaction is not performed, the mixture and the other raw materials are separated from each other, and a gap may be generated between them. By performing consolidation as in the present invention, the mixture and other raw materials are close to each other and easily come into contact with each other. Therefore, although CF is generated by the iron hydroxide and the CaO source, since the diffusion of CF is promoted, the assimilation with other raw materials can be advanced quickly. When CF produced by iron hydroxide and a CaO source is melted, the CF melt can be combined with a larger amount of other raw materials, so that the molded structure after firing can be densified and the strength can be improved. . It is conceivable to consolidate the raw material before the ignition furnace, but if it is consolidated before the ignition furnace, the ignition to the sintered raw material layer may be worsened.
Consolidation is performed downstream from the exit side of the ignition furnace. In addition, when the load applied to the sintered raw material layer is small for consolidation, the mixture and the other raw materials are not sufficiently brought close to each other, and the yield cannot be sufficiently improved. On the other hand, when the load is too large, the raw materials are too close to each other, the air permeability of the combustion gas and the like is deteriorated, and the yield may be reduced. FIG. 16 shows the relationship between the pressure at which a load is applied (squeezed down) to the sintered raw material layer and the yield. As shown in FIG. 16, the reduction load in consolidation is preferably in the range of 0.3 t / m ^{2 to} 1.2 t / m ² .

For this reason, on the exit side of the ignition furnace of the sintering machine, the raw material containing the mixture and other raw materials is applied with a load and consolidated. In performing the compaction, as shown in FIG. 17, a compacting roller (compacting device) 19 capable of compacting the moving sintering raw material layer from above is provided on the exit side of the ignition furnace 14, and this compaction is performed. Consolidation is performed by the roller 19.
The above-mentioned methods (i), (ii), and (iii) are combined to supply the combustible gas, combustible liquid, and exhaust gas to the sintered raw material, and to compact the sintered raw material. Good.

  Tables 1 to 8 summarize the examples sintered by the method for producing a sintered ore for iron making according to the present invention and comparative examples in which sintering was performed by a method different from the present invention.

In Examples and Comparative Examples, sintering was performed using a test sintering machine. As shown in FIG. 18, the test sintering machine is a sintering pot having a diameter of 300 mm and a height of 350 mm, and this sintering pot is made of steel and has a grading bottom surface. It can be sucked. The component target of the sintering raw material was SiO ₂ : 7.0 mass%, CaO: 18.0 mass%, Al ₂ O ₃ : 1.8 mass%, and the pseudo particle average particle size was about 3 mm. Ore A which is a sintering raw material is mined by Hamasley (made by Hamasley), and ore B is made by Rio Doce. In the sintering test, raw materials including a mixture of iron hydroxide and a CaO source (quick lime, slaked lime, limestone), ore A, ore B, limestone, and dolomide are mixed and granulated using water or the like, and sintered for testing. The machine was charged and the surface was ignited by an ignition burner, and air was sucked from below and baked.

  When supplying combustible gas, the hood was covered with the hood from the upper part, and combustible gas was supplied in the said hood. As the combustible gas, “COG”, “LPG”, “CH4”, and “CO” were used. When supplying the flammable liquid, the hood was covered with the hood from the top, and the flammable liquid was supplied into the hood. As the flammable liquid, waste oil, heavy oil, light oil, and ethanol were used. In addition, waste oil is various waste oil, for example, lubricating oil such as engine oil, cutting oil, fuel oil such as kerosene, gasoline, discarded oil such as solvent, edible oil, mineral oil composed of organic compounds, fatty oil Waste oil. In the examples and comparative examples, the waste oil used in the turbine was used.

  In addition, when supplying exhaust gas, after covering the hood, high-temperature air simulating exhaust gas was supplied. Furthermore, in performing the compaction, a circular plate having a diameter of 280 mm was placed on the sintering raw material layer from the upper part of the sintering pan, and a load was applied by placing a weight on the upper part of the circular plate. When the flame reached the bottom of the test sintering machine (sintering pan), it was finished and cooled. As shown in FIG. 9, since the sintering proceeds from the upper side to the lower side as it proceeds in the length direction of the sintering machine, the position in the sintering section is based on the position of the combustion zone in the sintering pot. Judgment was made. For example, in the body part (straight body part) of the sintering pan, the upper end is the start point, the lower end is the end point, and the section from the start point to the end point is replaced with the sintering section (0 to 100%) to determine the position. It was.

After sintering, the sintered cake was dropped on the iron plate 4 times from a height of 2 m, and the weight ratio of the sintered ore 5 mm or more after being dropped 4 times was used as the yield. That is, the yield was determined by the mass of sintered ore having a particle size of 5 mm or more / the mass of sintered cake. The production rate was determined by “Production rate = mass of sintered ore having a particle size of 5 mm or more / effective area of the sintering machine / sintering time”.
The sintering time was defined as the time required for the flame to reach the lowest layer from ignition in a test sintering machine.

In Examples 1 to 138, n of Fe ₂ O ₃ .nH ₂ O exceeds 1.0 and is 4.0 or less, and the molar ratio of CaO / Fe ₂ O ₃ is 0.5. It was mixed so that it might become less than 2.0. Moreover, in the Example, 2 mass% or more and less than 30 mass% of the mixture with respect to the other sintering raw material were charged.
Moreover, Examples 1-33 and 70-102 sintered by the combustion substance supply method (condition A). Examples 34 to 47 and 103 to 116 were sintered by the exhaust gas supply method (condition B), and Examples 48 to 55 and 117 to 124 were sintered by the combustion material supply method and exhaust gas supply method (condition C). Went. Examples 56 to 64 and 125 to 133 are sintered by a consolidation method (Condition D), and Examples 65 to 69 and 134 to 138 are a combustion material supply method, an exhaust gas supply method, and a consolidation method (Condition E). ) Was sintered.

On the other hand, the comparative example shows the valence n of iron hydroxide (Fe ₂ O ₃ .nH ₂ O), the molar ratio of CaO / Fe ₂ O ₃ , the blending amount of the mixture with respect to other sintering raw materials, and the above-mentioned sintered ore At least one of the manufactures is different from that defined in the present invention. Moreover, in the comparative example, it sintered without using the method (condition A-condition E) of this invention mentioned above.
FIG. 19 shows the relationship between the amount of heat and the yield for the examples from Condition A to Condition E. As shown in FIG. 19, in any of the conditions A to E, the yield could be as high as 57% or more. In addition, even if it compared the Example and the comparative example, even if it was the same production rate, the high yield was able to be achieved in the Example.

That is, according to the present invention, as described above, inferior iron ore that has been considered to be unusable in the past (iron hydroxide with a valence n exceeding 1.0, in other words, ore containing ultra-high crystal water) Was used to improve the yield.
In the embodiment disclosed this time, matters not explicitly disclosed, for example, operating conditions and operating conditions, various parameters, dimensions, weights, volumes, etc. of components deviate from the areas normally practiced by those skilled in the art. However, matters that can be easily assumed by those skilled in the art are employed.

DESCRIPTION OF SYMBOLS 1 Mixture 2 Other raw materials 3 Connective tissue 10 Sintering machine 11 Roller 12 Belt 13 Raw material supply apparatus 14 Ignition furnace 15 Wind box 16 Combustion supply apparatus 17 Exhaust gas supply hood 18 Exhaust gas circulation apparatus 19 Condensation roller (consolidation apparatus)

Claims (5)

4.0 and less iron hydroxide exceed Fe ₂ O ₃ · nH ₂ O n is 1.0, and a CaO source, the molar ratio of CaO / _Fe 2 _{O 3} is less than 2.0 more than 0.5 The mixed mixture is charged with 2% by mass or more and less than 30% by mass with respect to other sintering raw materials, and sintered.
Combustion gas and / or flammable liquid is used at the time of sintering when the sintering section starting from the ignition furnace and ending at the exhausting section is defined as 100% in the length direction of the sintering machine for sintering. A method for producing a sintered ore for iron making, wherein the sintered ore is supplied during 10% to 90% of the sintering section. 4.0 and less iron hydroxide exceed Fe ₂ O ₃ · nH ₂ O n is 1.0, and a CaO source, the molar ratio of CaO / _Fe 2 _{O 3} is less than 2.0 more than 0.5 The mixed mixture is charged with 2% by mass or more and less than 30% by mass with respect to other sintering raw materials, and sintered.
In the length direction of the sintering machine for sintering, when the sintering section starting from the ignition furnace outlet side and ending with the discharge portion is defined as 100%, during sintering, 60% to 100% of the sintering section A method for producing a sintered ore for iron making, characterized in that exhaust gas is recovered from the sintering machine during the period and the recovered exhaust gas is supplied while it reaches 10% to 90% of the sintering section.   During the sintering, exhaust gas is recovered from the sintering machine between 60% and 100% of the sintering section, and the recovered exhaust gas is supplied while it becomes 10% to 90% of the sintering section. The manufacturing method of the sintered ore for iron manufacture of Claim 1 characterized by the above-mentioned. 4.0 and less iron hydroxide exceed Fe ₂ O ₃ · nH ₂ O n is 1.0, and a CaO source, the molar ratio of CaO / _Fe 2 _{O 3} is less than 2.0 more than 0.5 The mixed mixture is charged with 2% by mass or more and less than 30% by mass with respect to other sintering raw materials, and sintered.
A method for producing a sintered ore for iron making, comprising applying a load to a raw material including the mixture and the other sintering raw material at the exit side of an ignition furnace of a sintering machine during sintering.   4. The iron making baking according to claim 3, wherein the sintering is performed by applying a load to the raw material including the mixture and the other sintering raw material on the exit side of the ignition furnace of the sintering machine. Production method of ore.