JP2012001758A - Method of charging sintering raw material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of charging a sintering raw material, capable of improving the productivity of sintered ore manufacturing further.SOLUTION: The method of charging a sintering raw material is characterized as follows. When charging the sintering raw material onto a pallet of a sintering machine to form a sintering raw material packed bed, when bisecting the formed sintering raw material packed bed into the upper half to be an upper layer part and the remaining lower half to be a lower layer part, while particle size segregation and charging of the sintering raw material are performed so as to increase the average particle diameter of the sintering raw material as approaching the lower part in the upper layer part, the sintering raw material is charged without performing the particle size segregation in a height direction in the lower layer part.

Description

  The present invention relates to a method of charging a sintering raw material onto a pallet of a Dwightroid (DL) type sintering machine.

  Sintered ores are usually baked with a mixture of multiple grades of powdered ore, mixed raw materials such as scales and reverse minerals, auxiliary raw materials such as limestone, quicklime, silica and serpentine, and carbon materials such as coke powder. After adding moisture to the blended raw material and mixing and granulating it with a drum mixer or a disk pelletizer to form pseudo particles, the pseudo raw particles are converted into a DL type sintering machine (hereinafter simply referred to as “sintering machine”). ), Ignited the carbon material of the surface layer portion of this sintered raw material packed layer (hereinafter also simply referred to as “packed layer”), and fired by sucking the air downward. can get.

Here, the productivity of the DL type sintering machine is greatly influenced by the product yield, which is the rate at which the product sintered ore can be collected from the firing rate and the sintered cake after firing.
Since the firing rate increases as the air permeability of the sintered material packed layer increases, it is intended to charge the sintered material by segregating the particle size in the height direction of the packed layer in order to improve the air permeability.

  As a concrete means for charging the sintered raw material by segregating the particle size in the height direction of the packed bed, the sintered raw material cut out by the drum feeder is classified using a sloping chute, roller feeder, ring slit wire (rsw), etc. In addition, fine particles are arranged on the upper layer side of the packed bed and coarse particles are arranged on the lower layer side (see, for example, Patent Documents 1 to 4). FIG. 1 is a typical example of the average particle size distribution in the packed bed height direction when the particle size segregation is intended.

  Here, at the time of firing, the upper layer side of the packed bed sucks air at room temperature simultaneously with the combustion of the carbonaceous material, so that the heat level is low and heat shortage easily occurs, whereas the lower layer side adds to the combustion heat of the carbonaceous material. Since the high-temperature combustion gas from the upper layer side is sucked, the heat level is high and heat surplus is likely to occur. On the other hand, since the coarse-grained sintered raw material is difficult to transfer heat to the inside, a higher heat level is required than the fine-grained sintered raw material for sufficient firing.

  Therefore, by the above charging means, a fine-grained sintering raw material is placed on the upper layer side of the packed bed with a low heat level, and a coarse-grained sintering raw material is placed on the lower layer side with a high heat level. Thus, it was thought that uniform firing could be achieved and the product yield was improved.

  However, as shown in FIG. 1 above, the segregation charging is performed so that the average particle diameter of the sintering raw material gradually increases from the uppermost surface of the packed bed toward the lower side and the average particle diameter is maximized in the lowermost layer. And the tendency for the product yield after baking to deteriorate was recognized.

  The reason why the product yield after firing deteriorates due to the segregation charging as described above was examined as follows.

  FIG. 2 shows the product yield after firing pseudo particles (sintering raw material) in a certain particle size range in relation to the particle size of the pseudo particles. Here, the product yield was evaluated based on the mass ratio of particles having a particle size of 10 mm or more after dropping 10 kg of a sinter cake having a particle size of 10 mm or more onto the iron plate 4 times from a height of 2 m. As shown in the figure, the product yield tends to decrease as the particle size of the pseudo particles increases. The reason for this is considered to be that the raw material packed layer formed of pseudo particles having a large particle size has a large gap. That is, in the sintering reaction, fine iron ore and auxiliary materials react at a high temperature to form a melt, and a sintered structure is formed in which unmelted coarse ore and the like are combined. At this time, if the gap of the raw material packed layer is large, the required amount of the melt filling one gap increases. Moreover, since the specific surface area is small when the particle size of the pseudo particles is large, the heat transfer rate is lowered, and the melt generation rate is also lowered. Therefore, the time required for the melt to fill one gap is also increased. For this reason, it is considered that if the firing time is substantially the same, voids are likely to remain, and such residual voids act as a starting point of breakage, and the strength of the sintered cake after firing is reduced and the product yield deteriorates.

  FIG. 3 is an example showing the relationship between the average particle size of the pseudo particles and the carbon concentration in the pseudo particles. In this example, the raw material ore having a particle size of 15 mm or less and the carbon material having a particle size of 6 mm or less are granulated, and the resulting granulated product (pseudo particles) is 10 mm, 5 mm, 3 mm in a wet state. Sieving with a sieve, -3mm pseudo particles are attached to the sieve mesh in a wet state and do not screen well, so after drying sufficiently with a dryer, further sieve with a 0.25mm sieve, The chemical analysis was performed for each particle size range, and the carbon concentration (based on the dry weight) was measured and obtained. In addition, the arithmetic average diameter of the upper and lower limit values of the mesh was adopted as the average particle diameter of the pseudo particles. However, the average particle diameter of 13 mm or more was assumed to be 16 mm assuming that the upper limit of the sieve mesh was 16 mm. As shown in the figure, it is recognized that the carbon concentration decreases as the average particle size of the pseudo particles increases. As in this example, there is often a particle size difference (raw material ore particle size> carbon material particle size) between the raw material ore and the carbon material, and therefore, in the region where the coarse pseudo particles gather, the carbon material is insufficient. The amount of heat necessary for firing is insufficient. For this reason, by providing an extreme particle size segregation in the packed bed, the calorific value is insufficient in the lower layer where the coarse pseudo particles gather, resulting in insufficient firing, and the yield of sintered ore after firing is reduced.

  In this way, by providing particle size segregation of the sintered raw material in the height direction of the raw material packed layer, the air permeability of the packed layer is improved and the firing rate can be increased, but the sintered ore after firing is increased. Since the product yield declines, it is not possible to improve productivity as a whole.

Japanese Patent Laid-Open No. 11-257872 JP 2000-63961 A JP 2005-226113 A JP 2005-320560 A

  Then, an object of this invention is to provide the charging method of the sintering raw material which can further improve the productivity of sintered ore manufacture.

  According to the first aspect of the present invention, when forming a sintered raw material packed layer by charging a sintered raw material onto a pallet of a sintering machine, the upper half of the formed sintered raw material packed layer is an upper layer portion. In addition, when the remaining lower half is divided into the lower layer portion, the upper layer portion is charged with particle size segregation so that the average particle size of the sintered material increases as it goes downward, while in the lower layer portion, A method for charging a sintered material, wherein the sintered material is charged without causing segregation in the height direction.

  According to the second aspect of the present invention, when forming a sintered raw material packed layer by charging a sintered raw material onto a pallet of a sintering machine, the upper half of the formed sintered raw material packed layer is an upper layer portion. When the remaining lower half is divided into the lower layer part, the average particle diameter of the sintered raw material increases in the upper layer part as it goes downward, and the ratio between the maximum value and the minimum value of the average particle diameter is 1.5. While the particle size segregation of the sintered raw material so as to be ~ 3.0, the maximum value of the average particle size of the sintered raw material in the lower layer portion and the average particle size of the sintered raw material in the entire lower layer portion In this method, the sintered raw material is charged with as little segregation as possible so that the ratio becomes 1.2 or less.

  According to the present invention, by providing particle size segregation in the height direction in the upper layer portion of the raw material packed layer and uniformly charging the sintered raw material so as not to cause particle size segregation in the lower layer portion, the air permeability of the entire packed layer is improved. As a result, it is possible to increase the product yield of sintered ore after firing by increasing the firing rate and preventing insufficient firing of the lower layer due to excessive particle size segregation. It has become possible to further improve the productivity of sinter production compared to the charging method in which the particle size is segregated to the lower part.

It is a graph which shows the particle size distribution of the sintering raw material in the height direction of the raw material filling layer formed by the conventional sintering raw material charging method. It is a graph which shows the relationship between the average particle diameter of a pseudo particle, and the product yield of the sintered ore after baking. It is a graph which shows the relationship between the average particle diameter of a pseudo particle, and the carbon concentration in a pseudo particle. It is a graph which shows the distribution of the average particle diameter and carbon concentration of a sintering raw material in the height direction of a raw material filling layer of the present invention example and a comparative example. It is a graph which compares and shows the product yield of the sintered ore after baking of the example of this invention and a comparative example. It is a graph which shows the temperature history in each part in a raw material packed bed of the example of this invention and a comparative example. It is the schematic which shows the structure of the charging apparatus of the sintering raw material which concerns on this invention. It is the schematic which shows another structure of the charging apparatus of the sintering raw material which concerns on this invention.

  Hereinafter, the present invention will be described in more detail.

  The method of charging the sintered raw material according to the present invention includes, for example, a plurality of brands of powdered ores, miscellaneous raw materials such as scales and return minerals, auxiliary raw materials such as limestone, quicklime, silica and serpentine, and powder coke, Mix an appropriate amount of carbonaceous material such as powdered anthracite, add moisture to this, mix and granulate with a drum mixer or disk pelletizer to make pseudo particles into a sintering raw material, and then use this sintering raw material for the sintering machine When forming the sintered raw material packed layer by charging on the pallet, the upper half of the formed sintered raw material packed layer is divided into the upper layer portion and the remaining lower half is divided into the lower layer portion. While the particle size segregation of the sintering material is increased so that the average particle size of the sintering material increases as it goes to the lower portion, the sintering material is charged without particle size segregation in the height direction ( That is, it is characterized by uniform charging).

  As shown in FIG. 3, pseudo particles (sintered raw materials are introduced by particle size segregation charging so that the average particle diameter of the sintered raw materials increases toward the lower layer in the upper layer portion). ), The carbon concentration in the pseudo-particles decreases, so that the carbon concentration distribution in the height direction in the upper layer portion of the packed bed is the highest on the top surface of the packed bed (that is, the amount of carbon material) Is the most), and decreases toward the bottom (that is, the amount of carbon material decreases).

  Due to the average particle size distribution and carbon concentration distribution of the pseudo particles in the height direction in the upper layer of such a packed bed, the combustion calorific value of the carbonaceous material is maximized near the top surface of the packed bed, and a high heat level is realized. At the same time, the heat transfer rate to the pseudo particles is maximized, and the lack of heat is more reliably resolved. And as it goes downward from the uppermost surface of the packed bed, the average particle size of the pseudo particles increases and the carbon concentration decreases, the calorific value of combustion of the carbon material decreases, and the heat transfer rate to the pseudo particles also decreases. However, since the high-temperature combustion gas from the uppermost surface side of the packed bed is sucked, a high heat level is maintained. As a result, high sinter strength is ensured over the entire height direction of the upper layer portion.

  On the other hand, the average particle diameter of the pseudo particles (sintering raw material) is made as constant as possible in the lower layer portion of the packed bed by “loading the sintering raw material in the lower layer portion without causing segregation in the height direction”. By approaching, coarse pseudo particles are prevented from concentrating on the lowermost layer of the packed bed, and an excessive decrease in the carbon concentration in the lowermost layer is prevented, and the sinter strength of the lowermost layer is also secured. Is done. As a result, high sinter strength is ensured over the entire height direction of the lower layer.

  Therefore, as described above, high sinter strength is ensured throughout the height direction of the packed bed, so that the yield of sintered ore after firing is reliably improved.

  As the degree of particle size segregation charging in the upper layer portion, the ratio of the maximum value and the minimum value of the average particle size of the sintered raw material in the upper layer portion is 1.5 to 3.0 (more preferably 1.7 to 2). 7, particularly 1.9 to 2.4), while the degree of non-particle size segregation charging (uniform charging) in the lower layer portion is the average grain size of the sintered raw material in the lower layer portion. It is preferable that the ratio between the maximum value of the diameter and the average particle diameter of the sintered raw material in the entire lower layer portion is 1.2 or less (more preferably 1.15 or less, particularly 1.1 or less).

  The ratio of the maximum value and the minimum value of the average particle size of the sintered raw material in the upper layer portion is 1.5 to 3.0 (more preferably 1.7 to 2.7, and particularly 1.9 to 2.4). The reason is that if this ratio is too small, the particle size segregation becomes insufficient, which may lead to insufficient heat at the top of the packed bed, while if the ratio is too large, the particle size segregation becomes excessive, This is because the fine particles gather at the uppermost part of the packed bed and the air permeability may deteriorate.

  Further, the ratio of the maximum value of the average particle diameter of the sintered raw material in the lower layer part to the average particle diameter of the sintered raw material in the entire lower layer part is 1.2 or less (further 1.15 or less, particularly 1 .1 or less), if this ratio is too large, coarse particles are collected in the lowermost layer, and the carbon concentration is also lowered, which may cause heat shortage.

  In order to realize a particle size distribution in the height direction of the packed bed in which the upper layer portion has particle size segregation and the lower layer portion has as little particle size segregation as described above, for example, as shown in FIG. The two feeders 5 and 6 are provided in the front and rear along the direction, and the raw material cut out by the drum feeder 5a from the upstream feeder 5 is directly charged onto the pallet 1 to form the lower layer 3. Then, the raw material cut out from the downstream feeder 6 by the drum feeder 6a is charged through the sloping chute 2 to form the upper layer portion 4. Alternatively, as shown in FIG. 8, only one mining device 5 is used, and the raw material cut out by the drum feeder 5 a is distributed to the upstream side and the downstream side in the traveling direction of the pallet 1 by the branch chute 7. The raw material distributed to is directly charged onto the pallet 1 to form the lower layer portion 3, and then the raw material branched downstream is charged through the sloping chute 2 to form the upper layer portion 4. You may do it.

  In order to confirm the effect of the present invention, the following sintering pot test was conducted.

  Using the same lot of sintering raw material collected at the actual sintering plant of Kakogawa Works, various average particle size distributions are formed in the raw material packed bed height direction of the sintering pot with an inner diameter of 100 mm, and the negative pressure is 3.5 kPa. (Constant) A sintering pot test was conducted under atmospheric suction conditions.

  FIG. 4A shows an average particle size distribution in the height direction of the raw material packed bed. Here, Comparative Example 1 is provided with particle size segregation throughout the packed bed height direction by charging using a slit bar feeding apparatus. Moreover, the comparative example 2 is uniformly charged in the whole packed bed height direction, and does not provide particle size segregation. In the invention example, the lower layer portion of the packed bed is uniformly charged and no particle size segregation is provided, and the upper layer portion is provided with a particle size segregation by charging using a slit bar feeder. .

  The average particle size distribution in the height direction of the packed bed is as follows. From the uppermost surface of the packed bed, the sintering raw material is sampled by the height of 1/10 of the packed bed height, and this is 10 mm, 5 mm, 3 mm, 0 Sieving with a 25 mm sieve, the arithmetic average diameter of the upper and lower limits between each sieve is taken as the representative diameter, and the average particle diameter is calculated by weighted average with the mass ratio of the sintering raw material present between each sieve It is measured by. However, for those over 10 mm, assuming that the upper limit of the sieve mesh is 16 mm, the representative diameter was 13 mm, and for those of 0.25 mm or less, the lower limit of the sieve mesh was 0 mm and the representative diameter was 0.125 mm.

  FIG. 4B shows the height direction of the packed bed for each of Comparative Examples 1 and 2 and the inventive example with reference to the relationship between the average particle diameter of the pseudo particles and the carbon concentration in the pseudo particles in FIG. 3 described above. The carbon concentration distribution is estimated and these are schematically shown.

  FIG. 5 shows comparison of the product yields after firing for each of Comparative Examples 1 and 2 and Invention Examples. As shown in the figure, in Comparative Example 1 in which particle size segregation was provided in the whole packed bed height direction, the product yield was as low as about 47%, whereas the upper layer portion of the packed bed was provided with particle size segregation, and the lower layer portion. In the invention example in which uniform charging was performed without providing particle size segregation, a high product yield of about 50% was obtained, which was almost the same as Comparative Example 2 in which uniform charging was performed without providing particle size segregation throughout the packed bed height direction. It was. Therefore, according to this invention, it turned out that a product yield improves clearly rather than the case where the particle size segregation is provided in the whole packed bed height direction.

  FIG. 6 shows the temperature history at each height of the packed bed for each of Comparative Examples 1 and 2 and Invention Example. As shown in the figure, it was found that, compared with Comparative Example 1, the inventive example can obtain a nearly equal high firing rate, but Comparative Example 2 has a lower firing rate. Therefore, according to this invention, it turned out that the high baking rate substantially equivalent to the case where the particle size segregation is provided in the whole packed bed height direction can be maintained.

  And since the productivity of sinter ore production is proportional to the product of the product yield and the firing rate, the results of FIGS. 5 and 6 show that the inventive example has higher productivity than any of Comparative Examples 1 and 2. It is clear that it is obtained, and from this, the productivity improvement effect of the present invention was confirmed.

Claims (2)

  When forming the sintered raw material packed layer by charging the sintered raw material on the pallet of the sintering machine, the upper half of the formed sintered raw material packed layer is divided into the upper layer part and the remaining lower half is divided into the lower layer part. In the upper layer portion, the sintered raw material is subjected to segregation and particle size segregation so that the average particle size of the sintered raw material increases as it goes downward. A method of charging a sintered material, which is performed without causing particle size segregation.   When forming the sintered raw material packed layer by charging the sintered raw material on the pallet of the sintering machine, the upper half of the formed sintered raw material packed layer is divided into the upper layer part and the remaining lower half is divided into the lower layer part. Then, in the upper layer portion, the average particle diameter of the sintered raw material increases as it goes downward, and the ratio of the maximum value and the minimum value of the average particle diameter is 1.5 to 3.0. While the sintered raw material is charged with particle size segregation, the ratio of the maximum value of the average particle size of the sintered raw material to the average particle size of the sintered raw material in the entire lower layer portion is 1.2 or less in the lower layer portion. Thus, the method for charging a sintered material is characterized in that the sintered material is charged as much as possible without causing segregation of particle size.