JP2013076105A - Method for manufacturing sintered ore - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a high-intensity and high-quality sintered ore having an excellent reducibility at a high yield, by using a downward-suction type sintering machine to combust a carbonaceous material and gas fuel in a charged layer.SOLUTION: The method includes steps of: charging a sintered material containing a fine ore and the carbonaceous material on a circulating pallet to form the charged layer; igniting the carbonaceous material of a surface of the charged layer; sucking air above the charged layer containing the gas fuel diluted to a combustion lower limit concentration or lower with a wind box located under the pallet to lead the air into the charged layer; and combusting the gas fuel and the carbonaceous material in the charged layer to manufacture the sintered ore. Part of high porosity is formed on both sides of the pallet of the sintering machine in the width direction.

Description

  The present invention relates to a method for producing a high-quality sintered ore for blast furnace raw material having high strength and excellent reducibility by using a downward suction type dwytroid sintering machine.

  Sinter ore, which is the main raw material of the blast furnace ironmaking method, is generally manufactured through a process as shown in FIG. The raw materials for sintered ore are iron ore powder, sintered ore sieving powder, recovered powder generated in steelworks, CaO-containing auxiliary materials such as limestone and dolomite, granulation aids such as quick lime, coke powder and anthracite Yes, these raw materials are cut out from each of the hoppers 1. The cut out raw material is added with an appropriate amount of water by the drum mixers 2 and 3 and the like, mixed and granulated to obtain a sintered raw material which is pseudo particles having an average diameter of 3 to 6 mm. This sintered raw material is then transferred to 400 to 800 mm on an endless moving type sintering machine pallet 8 from the surge hoppers 4 and 5 arranged on the sintering machine through the drum feeder 6 and the cutting chute 7. The charge layer 9 is charged with a thickness and is also referred to as a sintered bed. Thereafter, the carbon material on the surface of the charging layer is ignited by an ignition furnace 10 installed above the charging layer 9, and the air above the charging layer is passed through a wind box 11 disposed immediately below the pallet 8. By sucking downward, the carbonaceous material in the charging layer is sequentially burned, and the sintered raw material is melted by the combustion heat generated at this time to obtain a sintered cake. The sintered cake thus obtained is then crushed and sized, and an agglomerate of about 5 mm or more is recovered as a product sintered ore and supplied to a blast furnace.

  In the above manufacturing process, the carbonaceous material in the charging layer ignited by the ignition furnace 10 is continuously burned by the air sucked from the upper layer toward the lower layer in the charging layer, and has a width in the thickness direction. A combustion / melting zone (hereinafter also simply referred to as “combustion zone”) is formed. The melted portion of the combustion zone hinders the flow of air that is sucked in, so that the sintering time is extended and productivity is lowered. The combustion zone gradually moves from the upper layer to the lower layer as the pallet 8 moves downstream, and after the combustion zone has passed, the sintered cake layer ( Hereinafter, simply referred to as “sintered layer”) is generated. In addition, as the combustion zone moves from the upper layer to the lower layer, the moisture contained in the sintering material is evaporated by the combustion heat of the carbon material and concentrated in the lower sintering material that has not yet risen in temperature. To form a wet zone. If this moisture concentration exceeds a certain level, the voids between the sintered raw material particles that become the flow path of the suction gas are filled with moisture, which becomes a factor that increases the airflow resistance as in the melting zone.

  FIG. 2 shows that in the charging layer when the combustion zone moving in the 600 mm thick charging layer is at a position of about 400 mm on the pallet in the charging layer (200 mm below the charging layer surface). This shows the distribution of pressure loss and temperature, and the pressure loss distribution at this time shows that about 60% is in the wet zone and about 40% is in the combustion zone.

By the way, the production amount (t / hr) of the sintering machine is generally determined by the production rate (t / hr · m ² ) × sintering machine area (m ² ). That is, the production amount of the sintering machine varies depending on the width and length of the sintering machine, the thickness of the raw material charging layer, the bulk density of the sintering raw material, the sintering (combustion) time, the yield, and the like. Therefore, to increase the production of sintered ore, the permeability (pressure loss) of the charge layer is improved to shorten the sintering time, or the yield is increased by increasing the cold strength of the sintered cake before crushing. It is considered effective to improve the above.

Fig. 3 shows the change in temperature and time at a certain point in the charging layer when the sintered ore productivity is high and low, that is, when the pallet moving speed of the sintering machine is fast and slow. It is. The time for which the sintering raw material particles start to melt is maintained at a temperature of 1200 ° C. or higher is represented by T ₁ when the productivity is low and T ₂ when the productivity is high. Because at high productivity faster moving speed of the pallet, the high temperature zone holding time T _2, is shorter than the T ₁ of the at low productivity. However, if the holding time at a high temperature of 1200 ° C. or more is shortened, the firing becomes insufficient, the cold strength of the sintered ore is lowered, and the yield is lowered. Therefore, in order to produce a high-strength sintered ore in a short time with a high yield and high productivity, some measures are taken to extend the time for which the high-temperature sintered ore is held at a high temperature of 1200 ° C. or higher. It is necessary to increase the cold strength. In general, SI (shutter index) and TI (tumbler index) are used as indices representing the cold strength of sintered ore.

  FIG. 4 shows that the carbon material in the surface of the charging layer ignited in the ignition furnace is continuously burned by the sucked air to form a combustion zone, which sequentially moves from the upper layer to the lower layer of the charging layer. It is the figure which showed typically the process in which is formed. FIG. 5A shows the temperature distribution when the combustion zone is present in each of the upper layer portion, middle layer portion, and lower layer portion of the charging layer shown in the thick frame shown in FIG. It is shown schematically. The strength of the sintered ore is influenced by the product of the temperature and time maintained at a temperature of 1200 ° C. or higher, and the greater the value, the higher the strength of the sintered ore. Therefore, the middle layer and lower layer in the charging layer are preheated by being transported by the air sucked by the combustion heat of the carbon material in the upper charging layer, so that it can be held at a high temperature for a long time. On the other hand, the upper portion of the charge layer is not preheated, and therefore the combustion heat is insufficient, and the combustion melting reaction (sintering reaction) necessary for sintering tends to be insufficient. As a result, the yield distribution of the sintered ore in the cross section in the width direction of the charging layer becomes lower in the upper layer portion of the charging layer as shown in FIG. Also, the pallet both width end side cannot secure sufficient holding time in the high temperature range necessary for sintering due to heat dissipation from the pallet side wall and supercooling due to the large amount of air passing through, so the yield is also high. Lower.

  In order to cope with these problems, conventionally, the amount of carbonaceous material (powder coke) added to the sintered raw material has been increased. However, by increasing the amount of coke added, as shown in FIG. 6, the temperature in the sintered layer can be increased and the time for maintaining the temperature at 1200 ° C. or more can be extended. The maximum reached temperature exceeds 1400 ° C., and for the reasons explained below, the reducibility of the sintered ore and the cold strength are reduced.

  Non-Patent Document 1 shows the tensile strength (cold strength) and reducibility of various minerals produced in the sintered ore during the sintering process, as shown in Table 1. In the sintering process, as shown in FIG. 7, a melt starts to be generated at 1200 ° C., and calcium ferrite having the highest strength among the constituent minerals of sintered ore and relatively high reducibility is generated. To do. This is the reason why a sintering temperature of 1200 ° C. or higher is required. However, when the temperature rises further and exceeds 1400 ° C., more precisely, 1380 ° C., calcium ferrite is reduced to amorphous silicate (calcium silicate) having the lowest cold strength and reducibility, and reduced. It begins to decompose into skeletal secondary hematite that is easy to powder. In addition, secondary hematite, which is the starting point for reducing powderization of sintered ore, is obtained from Mag. As shown in the phase diagram of FIG. ss + Liq. Since it precipitates when it is heated up to the zone and cooled, it is possible to suppress the reduction powdering by producing sintered ore through the path (2) instead of the path (1) shown on the phase diagram. It is important to do.

  That is, in Non-Patent Document 1, in order to ensure the quality of sintered ore, the control of the maximum temperature reached during combustion and the holding time in the high temperature range are very important management items. It is disclosed that the quality of the ore is almost determined. Therefore, in order to obtain a sintered ore that is excellent in reduced powder (RDI), high strength, and excellent reducibility, the calcium ferrite produced at a temperature of 1200 ° C. or higher is decomposed into calcium silicate and secondary hematite. Therefore, it is important that the temperature in the charging layer is 1200 ° C. (calcium ferrite) without exceeding the maximum reached temperature in the charging layer during sintering of over 1400 ° C., preferably over 1380 ° C. It is necessary to keep the temperature above (solidus temperature) for a long time. Hereinafter, in the present invention, the time maintained in the temperature range of 1200 ° C. to 1400 ° C. will be referred to as “high temperature range retention time”.

  Several techniques have been proposed in the past for improving the yield reduction in the upper layer of the charging layer and improving the productivity. For example, in Patent Document 1, when producing sintered ore, in addition to coke added to the sintering raw material, an exothermic gas is added to the air sucked into the sintering raw material, A technique for improving the strength, production rate, and product yield of sintered ore has been proposed. However, since the technique of this patent document 1 raises the highest reached temperature at the time of sintering by burning coke and gaseous fuel, and aims at the improvement of the intensity | strength of a sintered ore, a production rate, and a yield, product sintering There is a problem that the reducibility (RI) of the ore is deteriorated.

  Therefore, as a technique for solving the above-mentioned problems, the inventors reduced the amount of carbonaceous material added to the sintering raw material, and then variously diluted below the lower combustion limit concentration downstream of the ignition furnace of the sintering machine. By introducing gaseous fuel into the charging layer from above the pallet and combusting the gaseous fuel in the charging layer, both the maximum temperature reached in the charging layer and the holding time in the high temperature range are controlled within an appropriate range. Techniques are proposed in Patent Documents 2 to 4 and the like.

Japanese Examined Patent Publication No. 46-027126 JP 2008-095170 A JP 2010-047801 A JP 2008-291354 A

“Mineral Engineering”; Hideki Imai, Toshihisa Takeuchi, Yoshiki Fujiki, (1976), p. 175, Asakura Shoten

  Applying the techniques of Patent Documents 2 to 4 to the method of producing sintered ore using a downward suction type sintering machine, reducing the amount of carbonaceous material added to the sintered raw material, and lowering the concentration below the lower limit of combustion When the diluted gaseous fuel is introduced into the charging layer, and the gaseous fuel is burned in the charging layer, the gaseous fuel burns in the sintered layer after the carbonaceous material burns. The width of the combustion / melting zone can be expanded in the thickness direction without causing the maximum temperature of the melting zone to exceed 1400 ° C., and the holding time of the high temperature region can be effectively extended.

  However, as shown in FIG. 5B, the product yield of sintered ore in the pallet not only has a distribution in the height direction, but also has a yield distribution in the width direction. The reduction in product yield at both width ends is large. However, the techniques of the above Patent Documents 2 to 4 are such that the gas flow distribution in the width direction of the sintering machine, that is, the air or gas fuel flow distribution in the width direction of the sintering machine under gaseous fuel blowing, The actual situation is that sufficient study has not been made on the influence on the sinterability and the quality of sintered ore.

  The present invention has been made in view of the above-described problems of the prior art, and its purpose is to sinter by burning a carbonaceous material and a gaseous fuel in a charging layer using a lower suction type sintering machine. An object of the present invention is to propose a method for producing a high-quality sintered ore with a high yield by optimizing the gas flow in the width direction of the sintering machine.

  The inventors have intensively studied to solve the above problems. As a result, by forming a portion with a high porosity at both width end portions where the yield is low in the pallet width direction of the sintering machine, a large amount of air and gaseous fuel can be supplied to that portion. The present inventors have found that a sintered ore having a high strength and excellent reducibility can be obtained at a high yield by extending the high temperature region holding time of the portion, and the present invention has been completed.

  That is, the present invention is to charge a sintered raw material containing fine ore and carbonaceous material on a circulating pallet to form a charging layer, ignite the carbonaceous material on the surface of the charging layer, and lower combustion lower concentration The air above the charging layer containing the diluted gaseous fuel is sucked in the wind box arranged under the pallet and introduced into the charging layer, and the gaseous fuel and the carbonaceous material are burned in the charging layer. In the method for producing a sintered ore, a method for producing a sintered ore is characterized in that portions having a high porosity are formed on both width end portions of the pallet of the charging layer.

  In the manufacturing method of the present invention, the both width end portions are within ¼ of the pallet width W.

  The high porosity portion in the production method of the present invention is a groove formed by inserting a rod-like body or plate-like body having a width of 5 to 30 mm to a depth of 10 to 60% of the charging layer thickness. It is characterized by the shape.

  Moreover, the manufacturing method of this invention forms the said high porosity part with the space | interval of 200-1000 mm.

  Moreover, the manufacturing method of this invention forms the said high porosity part so that the high temperature area holding time hold | maintained at 1200 to 1400 degreeC in the width direction both side part may be 150 second or more. Features.

  According to the present invention, it is possible to form a portion with a high porosity on the pallet both width end side of the sintered ore where the amount of sintering heat is insufficient, and more gaseous fuel and air can be supplied than other portions, Since the high temperature region holding time on the pallet both width end side can be extended, it is possible to greatly improve the product yield on the pallet both width end side.

It is a schematic diagram explaining a sintering process. It is a graph explaining the temperature distribution and pressure loss distribution in a sintered layer. It is a figure explaining the temperature distribution in the charging layer at the time of high production and low production. It is a schematic diagram explaining the change in the charging layer accompanying sintering progress. It is a figure explaining the temperature distribution when a combustion zone exists in each position of the upper layer part of the charging layer, the middle layer part, and the lower layer part, and the yield distribution of the sintered ore in the width direction cross section of the charging layer. . It is a figure explaining the temperature change in the charging layer by the change (increase) of the amount of carbon materials. It is a figure explaining a sintering reaction. It is a figure explaining the process in which a skeleton-like secondary hematite produces | generates. It is a figure explaining the example which forms a part with a high porosity in a charging layer. It is a figure explaining the influence which the part with a high porosity has on sintering. It is an example figure explaining the structure of the sintering test pot used for an example. It is a figure explaining the charging conditions of the sintering raw material to the sintering test pot in Example 1. FIG. It is a figure explaining the charging conditions of the sintering raw material to the sintering test pot in Example 2. FIG.

The basic technical idea of the present invention will be described.
As shown in FIG. 5 (b), the product yield of sintered ore in an actual sintering machine not only has a yield distribution in the pallet height direction (thickness direction), but also has a yield distribution in the pallet width direction. is there. In the techniques of Patent Documents 2 to 4 described above, the main focus is on improving the yield distribution in the height direction of the pallet. For improving the yield distribution in the width direction, the pallet width end sides (side walls) It was only possible to increase the number of pipes and nozzles for supplying gaseous fuel to the side). However, since the gaseous fuel supplied from above the charging layer is injected at a high speed from the small discharge holes, it is instantly diluted and uniformed. The expected effect could not be obtained.

  Therefore, the inventors have changed the idea from the prior art, and a method for facilitating the introduction of the uniformly diluted gaseous fuel into the charging layer on the both width end portions where the yield is low in the pallet width direction. Repeated examination. As a result, with respect to the charging layer in the conventional pallet shown in FIG. 9 (a), a portion having a high porosity is formed on both side ends of the pallet as shown in FIG. 9 (b). It has been found that by introducing gaseous fuel and air preferentially into the charging layer, a large amount of gaseous fuel and air are supplied to the ends of both widths, the retention time in the high temperature range is extended, and the yield is improved. It was.

  That is, as shown in FIG. 10 (a), when gaseous fuel is not supplied, if a portion with a high porosity is formed on both width end portions, the amount of carbon material in that portion decreases, so Although the heat is insufficient and the yield decreases, as shown in FIG. 10B, when gaseous fuel is supplied, the amount of gaseous fuel supplied to that portion increases, so the yield is improved. . However, the amount of gaseous fuel supplied is slightly reduced in the portions other than the width end portions, but since this portion is the portion where the highest temperature at the time of sintering tends to exceed 1400 ° C., the amount of gaseous fuel is reduced. Almost no influence by.

Next, the manufacturing method of the sintered ore of this invention is demonstrated concretely.
The method for producing a sintered ore according to the present invention uses a downward suction type sintering machine to charge a sintered raw material containing fine ore and carbonaceous material on a circulating pallet to form a charging layer. While igniting the charcoal on the surface of the charging layer, the air above the charging layer containing gaseous fuel diluted below the lower combustion limit concentration is sucked into the charging layer and introduced into the charging layer. In the point which is a method for producing a sintered ore by burning the gaseous fuel and the carbonaceous material in the charging layer, it is the same as the techniques of the conventional patent documents 2 to 4. However, the feature of the present invention is to supply a large amount of gaseous fuel and air by forming a portion with a high porosity in the charging layer on both width end portions where the product yield is low in the pallet width direction of the sintering machine. It is in. That is, since the pallet both width end sides cannot sufficiently secure the high temperature region holding time necessary for sintering only by the combustion heat of the carbonaceous material added to the sintering raw material, the yield is lowered. Therefore, in the present invention, a large amount of gaseous fuel is supplied to the both pallet width end sides and burned, so that a sufficient high temperature region holding time is secured at all positions in the width direction in the charging layer, and high quality is achieved. It is characterized by obtaining sintered ore.

  Here, the high temperature region holding time is a time during which the temperature is maintained at 1200 ° C. or higher and 1400 ° C. or lower, and 150 seconds or longer in order to produce a sintered ore with high strength and excellent reducibility at a high yield. It is desirable to ensure. The region where the high temperature region holding time is insufficient for 150 seconds or less only with the combustion heat of the carbonaceous material is a thermoelectric power at a predetermined depth inside the charged layer surface at a predetermined position in the pallet width direction of the actual sintering machine. It can be identified by inserting a pair and measuring the change over time of the temperature during sintering at that position. However, since the longer the high temperature region holding time, the higher the yield, the region where the high temperature region holding time is insufficient may be estimated from the yield distribution in the pallet cross section as shown in FIG. .

In order to extend the high temperature region holding time in the region where the high temperature region holding time is insufficient, it is necessary to supply the gaseous fuel at the stage where the sintering reaction of the portion is in progress. For example, in a 20% region on the pallet width direction end side (40% for both widths), when the high temperature region holding time is insufficient, the ignition furnace exit side in which the sintering reaction of that portion is proceeding It is necessary to supply a large amount of gaseous fuel to the area during the period up to the excavation part (effective captain). Further, it is preferable to supply the gaseous fuel in the longitudinal direction in the upstream region on the exit side of the ignition furnace because the high temperature region holding time tends to be insufficient in the surface layer side region of the raw material charging layer. -You may carry out in the whole area | region until completion of sintering.
However, as described above, in the prior art, it was difficult to supply the gaseous fuel only to a specific position in the machine width direction of the sintering machine. Therefore, in the present invention, a portion having a high porosity is formed in a region where a large amount of gaseous fuel is desired to be supplied, and the gas containing the gaseous fuel is made to flow easily, so that more gaseous fuel is supplied.

  As a method of forming a portion with a high porosity, a plate-like air slit or a rod-like air rod is inserted into the charging layer in the pallet of the sintering machine, and the stage before the charging layer enters the ignition furnace. If the pallet moves in the advancing direction in advance, a groove-like (slit-like) portion with a high porosity can be formed in the inserted portion.

  In addition, it is preferable that the ventilation slit or the ventilation rod has a width of about 5 to 30 mm and is inserted from the surface of the charging layer to a depth of 10 to 60% of the layer thickness. If the width is less than 5 mm or the depth is less than 10% of the layer thickness, the effect of improving the porosity formation is not sufficient, while the width is more than 30 mm or the depth is less than the layer thickness. If it exceeds 60%, a large amount of gaseous fuel flows in the gap forming part, and the gaseous fuel in other parts is excessively reduced, or the effect is saturated due to the self-destruction of the gap forming part. The cross section of the rod-like body or plate-like body used as the ventilation slit or the ventilation rod may be any shape such as a circle, an ellipse, a rectangle, a polygon.

  Moreover, when forming a part with a high porosity in a pallet width direction, it is preferable that the space | interval of the pallet width direction shall be the range of 200-1000 mm. If it is less than 200 mm, the movement of the sintering raw material may be hindered by a ventilation slit or a ventilation rod inserted in the charging layer, and if it exceeds 1000 mm, a portion with a high porosity may be formed. This is because a region where the effect does not reach occurs.

  Moreover, it is preferable that the gaseous fuel introduce | transduced in a charging layer in this invention is gaseous fuel diluted below the combustion minimum density | concentration of the gaseous fuel. If the concentration of the diluted gaseous fuel is equal to or higher than the lower combustion limit concentration, combustion may occur above the charging layer, and the effect of supplying the gaseous fuel may be lost or an explosion may occur. In addition, if the diluted gaseous fuel is at a high concentration, it will burn in the low temperature range where the sintering reaction has ended, even if it does not burn above the charge layer, which can effectively contribute to extending the high temperature range retention time. This is because there is a risk of not. Therefore, the concentration of the diluted gaseous fuel is preferably 3/4 (75%) or less of the lower combustion limit concentration at normal temperature in the atmosphere, more preferably 1/5 (20%) or less, more preferably combustion. It is 1/10 (10%) or less of the lower limit concentration. However, if the concentration of the diluted gas fuel is less than 1/100 (1%) of the lower limit of combustion, the calorific value due to combustion is insufficient, and the effect of improving the strength and yield of sintered ore cannot be obtained. It is preferable to set it to 1% of the lower limit of combustion. Looking at this for natural gas (LNG), the lower limit concentration of LNG at room temperature is 4.8 vol%, so the concentration of diluted gas fuel is preferably in the range of 0.05 to 3.6 vol%.

  The air containing the gaseous fuel diluted below the lower combustion limit concentration is a mixture of gaseous fuel previously diluted below the lower combustion limit concentration in the air above the charging layer, or in the air above the charging layer. Alternatively, it may be one that is instantly diluted below the lower combustion limit concentration by injecting (raw) gaseous fuel with high concentration at high speed and mixing it with air.

  Moreover, it is preferable to reduce the amount of carbonaceous material added to the sintering raw material (coke amount) equal to or more than the amount corresponding to the calorific value of the gaseous fuel added to the air. This is because when the gaseous fuel is added without changing the amount of the carbonaceous material, the total calorific value becomes excessive and the maximum temperature exceeds the upper limit (1400 ° C.) of the temperature range appropriate for sintering. This is because the production ratio of calcium ferrite decreases, calcium silicate increases, and the sintered ore is low in strength and inferior in reducing property. Therefore, in the present invention, the amount of carbonaceous material in the sintering raw material is a temperature range of 1200 to 1400 ° C., which is the highest temperature during sintering, depending on the amount of gaseous fuel added to the air (combustion heat). Desirably, it is necessary to adjust appropriately so that it may become the temperature range of 1200-1380 degreeC. Incidentally, when viewed in terms of calorific value, the gaseous fuel corresponding to 1 mass% of the amount of carbon material is about 1 vol% for LNG (liquefied natural gas) and about 0.5 vol% for propane gas.

  The sintering raw material having the blending ratio shown in Table 2 was put into a drum mixer and granulated to a size of about 5 mmφ. At this time, the silica in the obtained sintered ore was adjusted to be 4.9 mass% and the basicity was 2.0. Next, a carbonaceous material (powder coke) is added to the granulated particles to have the same structure as the test pan shown in FIG. 11, and the pan dimensions are depth: 400 mm × width: 800 mm × height: 400 mm. The test pan was filled to form a charging layer. At this time, as shown in FIG. 12A, the charging layer is formed by simply charging the sintering raw material (charging condition 1) and as shown in FIG. 12B. After inserting the sintering raw material, insert a ventilation slit in the width direction half part (400mm) of the pan, and slit of width: 10mm x depth: 200mm x depth: 200mm (part with high porosity) 2 were formed (charge condition 2).

Next, in a cold state without igniting the charged layer surface, gas was sucked from below the test pan with a blower, and the gas flow velocity on the charged layer surface was measured. The results are shown in Table 3.
From this result, in the charging condition 1 in which no groove is formed, the gas flow rate in the width direction is almost constant and 0.50 m / sec, whereas in the charging condition 2 in which the groove is formed, the gas flow rate in the charging condition 2 is The groove forming side is 0.57 m / sec, the non-grooved side is 0.46 m / sec, the average gas flow rate is 0.515 m / sec, and by forming a portion with a high porosity, It was confirmed that the air permeability was improved.

The sintering raw material having the blending ratio shown in Table 2 was put into a drum mixer and granulated to a size of about 5 mmφ. At this time, the silica in the obtained sintered ore was adjusted to be 4.9 mass% and the basicity was 2.0. Next, a carbonaceous material (powder coke) is added to the granulated particles to have the same structure as the test pan shown in FIG. 11, and the pan dimensions are depth: 400 mm × width: 800 mm × height: 400 mm. The test pan was filled to form a charging layer. At this time, the charging layer is formed as shown in FIG. 13 (a) under the condition that the sintering raw material is simply charged (charging condition 3) and as shown in FIG. 13 (b). After inserting the sintering material, insert a ventilation slit (width: 10 mm x depth: 200 mm x height: 200 mm) at a position 90 mm from the end of the test pan to form two slits (part with high porosity) As shown in Fig. 13 (c), and after charging the sintered raw materials, the ventilation slits (width: 10mm x) were placed at positions 90mm and 290mm from the end of the test pan. Depth: 200 mm × height: 200 mm) was inserted, and the three conditions (charging condition 5) were formed in which four slits (portions with a high porosity) were formed.
Next, the carbon material on the surface layer of the charging layer is ignited with an ignition device installed above the test pan, and divided into two conditions, with and without supplying gaseous fuel diluted with LNG to 0.4 vo 1% during sintering. A sintering experiment was conducted under five conditions T1 to T5 shown in Table 4. In each condition of T1 to T5, the experiment was performed by controlling the air volume during firing constant. The amount of carbonaceous material added to the sintered raw material was 5.0 mass% under the conditions of T1 and T2 where LNG was not supplied, and was reduced to 4.6 mass% under the conditions of T3, T4 and T5 where LNG was supplied. In this sintering experiment, the time required for sintering was measured, and the obtained sintered ore was measured for shutter strength SI according to JIS M8711 to determine the product yield and the production rate. Are shown in Table 4.

As a result of the above test, the condition of T2 in which a slit having a high porosity is formed without supplying gaseous fuel is compared with the condition of T1 in which no gas fuel is supplied and a portion having a high porosity is not formed. Although the sintering time is shortened, the cold strength SI and the product yield of the sintered ore are greatly reduced. On the other hand, under the condition of T3 in which only gaseous fuel is supplied without slit formation, although the sintering time is slightly extended, the cold strength SI and the product yield of the sintered ore are improved. Furthermore, with the conditions of T4 (example of the present invention) in which gaseous fuel is supplied after forming slits at the ends, the sintering time is improved over the condition of T3, and the cold strength SI and product of the sintered ore are improved. Yield is further improved. As a result, it can be seen that the production rate is greatly improved in the condition of the present invention example of T4 as compared with the condition of T1 in which neither the supply of gaseous fuel nor the formation of slits is performed.
On the other hand, in T5 in which the slit is uniformly formed in the width direction of the test pan and gaseous fuel is supplied, the sintering time is shorter than T4, but the cold strength SI and the product yield of the sintered ore are reversed. Therefore, the production rate is reduced as compared with the T3 condition in which only the gaseous fuel is supplied without the formation of slits. This is because, as shown in FIG. 5 (b), when a slit is also formed in the central portion in the width direction where the yield of sintered ore is originally high, the firing rate is uneven at that portion and the yield is reduced. It is thought to make it.

  The sintering technique of the present invention is not only useful as a technique for producing sintered ore used as a raw material for iron making, particularly as a blast furnace, but can also be used as another ore agglomeration technique.

1: Raw material hopper 2: Drum mixer 3: Rotary kiln 4, 5: Surge hopper 6: Drum feeder 7: Cutting chute 8: Pallet 9: Charging layer 10: Ignition furnace 11: Wind box 12: Cut-off plate

Claims (5)

A gaseous fuel diluted with a sintered raw material containing fine ore and charcoal on a circulating moving pallet to form a charging layer, igniting the charcoal on the surface of the charging layer and diluting below the lower combustion limit concentration Suction ore is produced by sucking the air above the charging layer, including the slag, into the charging layer by sucking it with a wind box placed under the pallet, and burning the gaseous fuel and carbonaceous material in the charging layer. In the way to
A method for producing a sintered ore, characterized in that high porosity portions are formed on both width end portions of the pallet of the charging layer. 2. The method for producing a sintered ore according to claim 1, wherein the both width end portions are within ¼ of the pallet width W. 3. The portion having a high porosity is a groove formed by inserting a rod-like body or plate-like body having a width of 5 to 30 mm to a depth of 10 to 60% of the charging layer thickness. The manufacturing method of the sintered ore of Claim 1 or 2. The method for producing a sintered ore according to any one of claims 1 to 3, wherein the high porosity portions are formed at intervals of 200 to 1000 mm. The high porosity portion is formed so that a high temperature region holding time of 150 seconds or more held at 1200 ° C. or higher and 1400 ° C. or lower on both side portions in the width direction of the pallet is formed. The manufacturing method of the sintered ore of any one of Claims 1.

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