JP5935979B2 - Method for producing pseudo-particles for producing sinter and method for producing sinter - Google Patents

Description

  The present invention provides a pseudo ore for sinter production that is advantageously used when producing a high strength sintered ore while maintaining high productivity when producing a sinter using a Dwytroid type sintering machine. The present invention relates to a method for producing particles and a method for producing sintered ore using the pseudo particles.

In recent years, the steel industry is regarded as a problem of the effect on global warming caused by carbon dioxide ( CO ₂ ) discharged in large quantities, and has a serious problem of reducing CO ₂ emissions. In response to such problems, the operation of a low reducing material ratio is desired for the recent blast furnace operation. In general, the reducing material ratio is the total amount of reducing material blown from the tuyere and coke charged from the top of the furnace used to produce 1 ton of hot metal. Is called “RAR (Reducing Agent Ratio)”. In order to perform low RAR operation in a blast furnace, the following method is considered effective.
(A) To reduce the particle size of the iron-containing raw material charged in the blast furnace and increase the heat receiving efficiency and the reaction interface area with the reducing gas.
(B) Improving the reducibility of the iron-containing raw material charged into the blast furnace.
(C) At the time of blast furnace operation, the gas flow rate should be improved by suppressing the surrounding gas flow.
(D) To reduce the amount of heat removed from the blast furnace body.

  However, during low RAR operation, the ratio of the iron-containing raw material to be charged and the coke increases, resulting in deterioration of air permeability in the upper part of the furnace, deterioration of air permeability in the lower part of the furnace due to deformation and enlargement of the cohesive zone. Invited, stable blast furnace operation may be difficult. Therefore, in order to realize a stable low RAR operation, the properties of sintered ore, which accounts for about 70% of the iron-containing raw material, are very important.

The sintered ore used as a blast furnace raw material is generally manufactured through a process as described below.
(1) First, in addition to iron ore powder having a particle size of 10 mm or less, return ore, a secondary raw material made of a SiO ₂ containing raw material made of silica, serpentine, various smelting slags, or a CaO containing raw material such as limestone, and powder coke Alternatively, solid fuel powder serving as a heat source such as anthracite is added with an appropriate amount of water, mixed in a drum mixer, and granulated to produce pseudo particles for sinter production.

(2) Next, the pseudo particles are charged on a pallet of a Dwytroid type (DL) sintering machine so as to have a thickness of, for example, about 500 to 700 mm, and are deposited on the pallet by the charging. The solid fuel in the surface portion of the packed bed of particles (hereinafter referred to as “raw material packed bed”) is ignited, and the solid fuel in the raw material packed bed is combusted by using the air sucked downward, and the combustion heat generates pseudo particles. Sinter into a sintered cake. Thereafter, the sintered cake is crushed and sized so that a product having a certain particle size or more is used as a product sintered ore. In addition, the thing with a small particle diameter after sizing is reused as a sintering raw material as a return ore.

  In general, as one of the factors affecting the operation of a blast furnace, there is a reducibility of the product sintered ore (hereinafter simply referred to as “sintered ore”). The reducibility of the sinter is related to the gas utilization rate in the blast furnace and has a good negative correlation with the RAR. When the reducibility of the sinter is improved, the RAR in the blast furnace decreases. To do. In addition, the cold strength of the sintered ore is also an important factor in ensuring air permeability in the blast furnace, and a lower limit is set for the cold strength in the operation of the blast furnace.

However, in recent years, the use of sintered ore tends to increase due to high blast furnace ratio operation of the blast furnace, or the deterioration of raw material quality (increase in high crystal water ore, increase in Al ₂ O _{3 in} the ore, As a result of the increase in fine ore, etc.), it is becoming difficult to ensure good air permeability of the raw material packed layer deposited on the pallet of the sintering machine and to ensure sufficient sintering time. There are concerns about a decrease in yield, a decrease in yield, and a decrease in the cold strength of sintered ore.

  In order to improve the air permeability of the raw material packed layer, conventionally, a method for granulating a sintered raw material has been studied for such problems. For example, in Patent Document 1, in a method of manufacturing a sintered raw material by forming pseudo particles by rolling while adding water to one or more blends of sintered raw materials containing coarse particles and fine powders Before the addition of the moisture, the moisture concentration distribution of the sintering raw material is calculated as a function of the moisture concentration after addition using the brought-in moisture concentration of the sintering raw material, and the calculated moisture concentration distribution and the sintering The pseudo-particle size distribution is calculated based on the particle size distribution of the binding raw material, and the post-addition water content is such that the pseudo-particle size distribution is a particle size distribution in which the amount of the pseudo-particles having a particle size of 2 mm to 10 mm is the maximum. A method is disclosed in which the concentration is determined and the amount of water added is controlled with the water concentration after the addition as a target.

  Further, Patent Document 2 describes the moisture concentration at which the sintered raw material has adhesive strength from the saturated water absorption rate and the pre-granulation particle size distribution of each of the plural types of sintered raw materials individually accommodated in a plurality of sintered raw material tanks. A critical moisture concentration which is a lower limit value is calculated for each of the sintering raw materials, and among the sintering raw materials respectively accommodated in the plurality of sintering raw material tanks, at least the sintering water having a large saturated water absorption rate. After adding moisture to the binding raw material to obtain a moisture concentration equal to or higher than the saturated water absorption rate, blending a plurality of types of the sintering raw materials while adding moisture so that the moisture concentration is equal to or higher than the critical moisture concentration, Disclosed is a method of forming pseudo particles by rolling.

  However, for these methods of adding the amount of water corresponding to the target water concentration proposed in Patent Document 1 and the saturated water absorption rate disclosed in Patent Document 2, the water content is due to the dispersibility of water. However, there is a problem that the fine powder does not sufficiently spread, the adhesion of the fine powder is not sufficient, and the granulation effect is small.

  In Patent Document 3, a raw material for sintering whose moisture is adjusted to 7.5% or more and 9.0% or less by mass% is granulated, and the moisture of the granulated raw material is transferred from the granulator to the sintering machine. A method for granulating a sintered raw material, characterized in that it is reduced by using a high-temperature gas between the delivery sides of the feed section and used as a raw material for sintering, is disclosed.

However, when the sintering raw material falls below the moisture having adhesive force in the course of the drying process, the adhesive force is lost and the powder is pulverized. If the sintered raw material exceeds the moisture concentration having adhesive force in the process, the void between the pseudo particles is filled with excess water, which causes a problem that the flow of air passing through the raw material packed bed is hindered.

  Further, in Non-Patent Document 1, FIG. 2 discloses the relationship between the amount of added water, the air permeability of the raw material packed layer, and the particle size of the pseudo particles. According to the disclosed contents of Non-Patent Document 1, up to 7.5 mass% of moisture, the absorption of moisture into the pseudo-particles is gradually saturated, resulting in a binder effect due to moisture that wets the particle surface, and granulation. It has been reported that the pseudo particle size of the particles is increased and the air permeability is improved.

  However, if the water content exceeds 7.5 mass%, the diameter of the pseudo particles tends to continuously increase, but the excess water fills the gaps between the pseudo particles, so that it passes through the raw material packed bed. The problem arises in that the flow of air is disturbed.

JP 11-61281 A JP 2000-1725 A JP 2006-336064 A “Iron and Steel” Japan Iron and Steel Institute 68 (1982), p. 2174

  The techniques disclosed in the above-mentioned documents are mainly methods for predicting an appropriate amount of moisture before manufacturing pseudo particles and dealing with fluctuations in the quality of sintered raw materials. However, productivity cannot be significantly improved only by setting an appropriate moisture at the time of granulation of the sintered raw material.

  The object of the present invention is to solve the above-mentioned problems of the prior art and to improve the air permeability of the raw material packed bed during operation of the sintering machine, without causing a decrease in strength and yield. The object is to propose a method for producing pseudo-particles and a method for producing sintered ore used for producing sintered ore, which are effective in improving the production rate of ore.

The present invention has by granulation by adding excess water than the proper moisture sintering raw material powder, the particle size larger than the particle size to be formed under該適positive moisture, the water fine layer Forming pseudo particles, and then drying the pseudo particles having the water-containing fine powder layer to reduce the moisture of the pseudo particles after drying to (appropriate moisture-1) mass% to (appropriate moisture + 1) mass%. It is the manufacturing method of the pseudo particle for the sinter manufacture characterized by the above.

Further , by adding granulation to the sintering raw material powder in excess of the appropriate moisture and granulating, the pseudo particle having a hydrous fine powder layer having a particle size larger than the particle size to be formed under the appropriate moisture The pseudo particles having the water-containing fine powder layer are dried, and the moisture of the pseudo particles after drying is reduced to (appropriate moisture-1) mass% to (appropriate moisture + 1) mass%, and the moisture is reduced. The quasi-particles are charged into a sintering machine and sintered to produce a sintered ore.

The present invention can be more preferably implemented by the following configuration.
(1) The appropriate moisture is moisture that maximizes the air permeability of the raw material packed layer filled with pseudo particles.
(2) The excess moisture is 1.1 to 1.5 times the appropriate moisture,
(3) The excess moisture is 1.25 to 1.5 times as much as the appropriate moisture,
(4) The excess water is 1.3 to 1.45 times the appropriate water ,
(5 ) The said drying is a drying process which makes the water | moisture content of the pseudo-particles after drying the water | moisture content of appropriate water mass%-(appropriate water +0.5) mass%.

  According to the present invention having the above-described configuration, once the water is added in excess of the appropriate moisture and granulated in a state where the moisture is sufficiently distributed to the fine powder, the particles formed under the appropriate moisture Pseudo particles with a particle size larger than the diameter, and then dried to near the proper moisture so that the pseudo particles do not break after granulation or the pseudo particles do not break even if they are placed By processing, excess added moisture that contributed to the large particle size is removed, so that the air permeability of the raw material packed layer expected when adding excessive moisture is not simulated, The effect of expanding the particle size of the particles can be enjoyed.

  By adopting such a configuration, in the present invention, the air permeability of the raw material packed layer is improved, and as a result, the sintering time can be shortened, so the cold strength and yield of the product sintered ore are reduced. The production rate of sintered ore can be improved without incurring.

It is a figure which shows the outline | summary of the sintering test process according to a conventional method. It is a figure which shows the relationship between granulation water | moisture content and air permeability. It is a figure which shows the outline | summary of the sintering test process according to this invention. It is a figure which shows the relationship between the water | moisture content before drying and after drying, and the arithmetic mean diameter of a pseudo particle. It is a figure which shows the relationship between granulation water | moisture content and the weight ratio of the pseudo-particles after drying. It is the cross-sectional photograph of the pseudo particle granulated by appropriate water | moisture content +3.0 mass%, and was dried, and its schematic diagram. It is the cross-sectional photograph of the pseudo particle granulated by appropriate water | moisture content +5.0 mass%, and dried, and its schematic diagram. It is a figure which shows the relationship between the water | moisture content before drying, and after drying, and sintering time. It is a figure which shows the relationship between the water | moisture content before drying, and after drying, and a production rate. It is a figure which shows the relationship between the water | moisture content before drying, and after drying. It is explanatory drawing of the sintering test process used in the Example. It is a figure which shows the relationship between the water | moisture content of the pseudo particle and the arithmetic mean diameter of a pseudo particle explaining the effect of an Example. It is a figure which shows the relationship between the water | moisture content of the pseudo particle and the arithmetic mean diameter of a pseudo particle explaining the effect of an Example. It is a figure which shows the relationship between the water | moisture content of the pseudo particle and the arithmetic mean diameter of a pseudo particle explaining the effect of an Example.

  The inventors first considered giving sufficient adhesion to the fine powder by sufficiently spreading moisture to the fine powder. Therefore, when producing granulated pseudo particles to be charged into a DL sintering machine, first, the moisture content of the raw material packed layer formed by depositing the pseudo particles is higher than the proper moisture content of the pseudo particles that maximizes the air permeability. Add water to get moisture. Thereby, pseudo particles having a large particle size are obtained. Thereafter, various studies were made on drying conditions for preventing the voids between the pseudo particles from being filled with excessive moisture. At that time, it was discovered that by drying to the vicinity of the appropriate moisture, a pseudo fine particle having a water-containing fine powder layer composed of moisture and agglomerated fine powder on the outer side of the pseudo particle, and having a large particle size, was obtained. Led to the development. That is, in the present invention, when producing granulated pseudo particles to be charged into a DL sintering machine, firstly, the amount of water is more than the appropriate amount of water, that is, an excessive amount of water is added to the proper amount of water. In this method, pseudo particles having a large particle size are used, and then dried to the vicinity of appropriate moisture.

  Therefore, in the present invention, in particular, the water is added in excess of the appropriate water, granulated, and immediately dried to near the appropriate water without curing. As a result, since the pseudo particles have a water-containing fine powder layer in which fine powders are aggregated on the outside, they become pseudo particles having a large particle size without being reduced to a pseudo particle size formed with appropriate moisture.

  In this way, since moisture is removed by drying until it is close to the appropriate moisture, the flow of air passing through the raw material packed bed by filling the voids between the pseudo particles during the sintering operation as in the past On the other hand, since it has a water-containing fine powder layer in which fine powder is aggregated, the effect of enlarging the particle diameter can be enjoyed. Moreover, the product sintered ore can improve the productivity of the sintered ore without causing a decrease in cold strength and yield.

  The present invention developed under such a concept has been discovered through tests as described below. That is, the inventors clarified the general mechanism for improving the air permeability of the raw material packed bed formed by inserting the pseudo particles on the pallet of the sintering machine and the production rate of the sintered ore. Granulation and sintering tests were performed with a testing machine as shown in FIG. 1 simulating the sinter production process. In this test, coarse iron ore (less than 8mm), fine iron ore (0.125mm to 0.063mm), iron ore raw materials including return ore, basicity adjustment silica, quick lime, limestone, etc. Powder coke as an auxiliary material and heat source is blended, and the resulting sintered raw material powder 1 is mixed with a disk-type mixer 2, and then the mixed sintered raw material powder is transferred to a drum mixer 3 to add water. Then, the drum mixer 3 was rotated and granulated to obtain pseudo particles.

  Next, in order to estimate the appropriate moisture that maximizes the air permeability of the raw material packed layer in the sintering machine, the inventors, as shown in Table 1, have two levels of sintering in which the ore type and its blending ratio are different. About raw material mixing | blending, the relationship between granulation water | moisture content and air permeability (JPU index) was measured. FIG. 2 shows the relationship between the measured granulated moisture and air permeability (JPU index). As seen in this figure, the air permeability of the raw material packed layer varies greatly depending on the blending ratio of the sintered raw material powder used, and the air permeability is 7.6 mass% at level 1 and 5.5 mass% at level 2. It turned out to be the maximum. The air permeability can be obtained by air permeability (JPU index) = (air volume / suction area) × (layer thickness / suction negative pressure) 0.6, and the larger the JPU index, the better the air permeability. .

  In general, the appropriate moisture depends on the type of sintered raw material powder (determined by the properties of the ore and the blending ratio), and is in the range of 3.5 to 10.0 mass%.

  Furthermore, in order to investigate the superiority of the present invention, a pseudo-particle production test was conducted in which the excess moisture was added to the appropriate moisture and granulated, and then immediately dried. In this test, a sintered raw material powder whose main component composition is shown in Table 2 after blending was used. The amount of water added to the drum mixer 3 shown in FIG. 3 is based on the above-mentioned appropriate moisture T1: 7.6 mass% corresponding to the appropriate moisture, and on the other hand, T2 is an example in which moisture is excessively added. 8.6 mass% (appropriate moisture + 1 mass%), T3: 9.6 mass% (appropriate moisture + 2 mass%), T4: 10.6 mass% (appropriate moisture + 3 mass%), T5: 11.6 mass% (appropriate moisture + 4 mass%), T6: Tested at 6 levels of 12.6 mass% (appropriate moisture +5 mass%).

  In a normal sintering operation, the pseudo particles immediately after granulation by the drum mixer 3 are directly charged on a pallet of a sintering machine as shown in FIG. However, in the pseudo particle production test, as shown in FIG. 3, the pseudo particles obtained by granulation are placed in the vat 4 and immediately put in the dryer 5 set to 200 ° C. for a predetermined time (5 to 20 minutes). ) Dried. However, it is not preferable to completely dry, for example, more than necessary, because the pseudo particles are destroyed. Desirable drying time is measured in advance with the time-dependent change in the amount of water evaporated, and the moisture content of the pseudo particles after drying is about ± 1 mass% of the initial appropriate moisture (a value close to returning to about 7.6 mass%). Adjusted to return. The above pseudo-particles granulated with excess moisture and dried to the vicinity of suitable moisture retain the moisture necessary for the fine ore to form pseudo-particles. The particle size suitable for ensuring the air permeability of the packed bed can be maintained. Further, the value of the proper moisture ± 1 mass% is a range that can be dried to such an extent that even if it is dried, the pseudo particles whose particle diameter has been increased by adding more water than the proper moisture does not collapse. In addition, it is preferable to adjust so that it may return to a suitable water | moisture content +/- 0.5 mass%.

  Table 2 shows a typical chemical composition after blending of the sintering raw material powder used in this test, and Table 3 shows the ratio of moisture added during granulation and the dryness (appropriate moisture ± 1 mass) measured immediately before the sintering test. The moisture content of the pseudoparticles after drying to%) is shown.

  FIG. 4 shows the arithmetic average diameter of the pseudo particles (in the figure, the moisture at the time of granulation and the moisture after the drying are displayed) measured and calculated using a sieve after drying after granulation by the drum mixer 3. As shown in FIG. 4, when the water content during granulation is 8.6 to 11.6 mass%, the arithmetic average diameter of the particles increases as the granulated water content increases. The reason for this is that when moisture is added excessively, when moisture absorption into the pseudo-particles is saturated, the excess moisture stays on the particle surface to form a water film, and the moisture exerts a binder action. It is considered that the fine powder aggregates in the water film portion, and the particle diameter of the pseudo particles granulated by forming the water-containing fine powder layer is increased.

  FIG. 5 shows sifting of pseudo particles obtained by granulation by adding water in excess of the proper moisture of 10.6 mass% or 12.6 mass% with respect to the original proper granulated moisture: 7.6 mass%. Shows the particle size distribution. As is apparent from FIG. 5, when the particle size distributions of granulated moisture 7.6 mass%, 10.6 mass%, and 12.6 mass% are compared, when the moisture during granulation increases, the granulated moisture 10 In the case of 0.6 mass%, the ratio of coarse particles of 8.0 to 1.0 mm is increased, and the ratio of fine powder of -1 mm is decreased.

  On the other hand, as shown in FIG. 4, in the region where the granulated moisture is +12.6 mass%, the arithmetic average diameter of the pseudo particles decreases as the granulated moisture increases. That is, as can be seen from the results shown in FIGS. 4 and 5, the addition of 12.6 mass%, which is +5 mass% over the appropriate moisture of 7.6 mass%, causes the core particle part to collapse and rather does not aggregate. It can be seen that the fine powder ratio increases.

  Therefore, in the case of the present invention, the excess water added is in the range of 1.1 times the appropriate moisture (granulated moisture 8.4 mass%) to 1.5 times (granulated moisture 11.4 mass%). preferable. More preferable excess water is 1.25 times to 1.5 times, more preferably 1.30 times to 1.45 times the proper water content.

FIG. 6 is a cross-sectional photograph of a pseudo particle that has been granulated with an appropriate moisture + 3.0 mass% and dried, and a schematic diagram thereof.
FIG. 6 (a) is a cross-section of the pseudo-particle showing a state in which hemispherical core particles and fine powder particles are granulated to a water content of 10.6 mass% by adding water in excess of the appropriate water and placed on the preparation. It is a photograph and its explanatory drawing.
FIG. 6B is a cross-sectional photograph of the pseudo-particles and an explanatory diagram showing a state in the middle of drying to an appropriate moisture equivalent (7.5 mass%).
FIG. 6C is a cross-sectional photograph of the pseudo-particles and an explanatory view thereof showing a state of drying to an appropriate moisture equivalent (7.5 mass%).

  The photograph in FIG. 6 (a) is a granulated state in which excess moisture within the scope of the present invention is added and is sufficiently granulated, and the pseudo particles have a large particle size due to excess moisture and fine powder. Is obtained. The photograph in Fig. 6 (b) shows a state in the middle of drying to an appropriate moisture equivalent (7.5 mass%), and the fine powder existing in the vicinity is agglomerated on the surface of the quasi-particle by riding on the convection generated as the moisture decreases. It can be observed that it has a water-containing fine powder layer composed of water and agglomerated fine powder on the outside of the pseudo particles, and there are few unagglomerated fine powders. As a result, as shown in the photograph of FIG. 6B and the schematic diagram on the right side, it is a pseudo particle having a large particle size that does not contain excessive moisture.

  On the other hand, FIG. 6 (c) is a diagram in which excess moisture within the scope of the present invention is added and granulated, and then it is removed to remove about 3 mass% of water corresponding to appropriate moisture (7.5 mass%). The state after processing is shown. In addition, even after the fine powder remaining as non-aggregated / non-adhered is agglomerated and adhered to the surface of the pseudo particle and the phenomenon of increasing the particle size of the pseudo particle is dried to an appropriate moisture equivalent (7.5 mass%). It can be observed that it is maintained.

  Next, FIGS. 7 (a) to (c) are examples outside the scope of the present invention, and as excess moisture, granulate after adding an excess moisture of 5.0 mass% to the appropriate moisture, Then, it is an example when it is dried. In this example, as shown in the photograph and schematic diagram of FIG. 7 (b), which is in the middle of drying to an appropriate moisture equivalent, the interval between the pseudo particles and the fine powder existing in the surroundings increases due to the large amount of moisture, The water-containing fine powder layer composed of a water film and agglomerated fine powder as shown in FIG. 6 (b) is observed as a residual fine powder that does not agglomerate due to the convection of moisture generated in the coagulation drying process due to moisture reduction. Fine powder that cannot be contained is generated. Therefore, it turns out that the fine powder of this example does not contribute to expansion of a pseudo particle size. As shown in the photograph and schematic diagram of FIG. 7 (c), it appears more clearly when dried, and a lot of fine powder remaining as non-aggregated / unattached is observed, and the effect of the present invention does not occur. I understand that.

  Next, FIG. 8 and FIG. 9 show the relationship between the moisture before and after drying the pseudo particles, the sintering time, and the production rate when the method suitable for the method of the present invention is performed. As shown in these figures, the appropriate moisture for granulation: 7.6 mass%, while granulation moisture (moisture before drying) is excessively added as 10.6 mass% and 11.6 mass%, It can be seen that the settling time is shortened and the production rate is improved. On the other hand, if this moisture exceeds 11.6 mass% to 12.6 mass%, that is, if the moisture added excessively exceeds 1.5 times the appropriate moisture, the air permeability deteriorates, the sintering time increases, and the production rate Has also declined.

  FIG. 10 shows the effect on the yield of sintered mineral products of +10 mm investigated after the sintering test. As can be seen from this figure, at least the amount of water added in accordance with the method of the present invention is about 1.1 times (appropriate moisture + 1 mass%) to about 1.5 times (appropriate moisture + 4 mass%) of appropriate moisture. No decrease in yield was observed, but the yield decreased at over 1.5 times (12.6 mass%).

  As described above, according to the present invention, when the pseudo particles to be charged into the sintering machine are granulated while adding water with a drum mixer, they are originally required for granulation. The pseudo-particles are granulated by adding excess moisture to the proper moisture of the above, thereby forming pseudo-particles having a large particle size, and then the pseudo-particles are desirably dried immediately, The pseudo particles are dried to a moisture equivalent to appropriate moisture. This improves the air permeability of the raw material packed bed on the pallet during operation with the sintering machine, and improves the productivity of the sintered ore without reducing the cold strength and yield of the sintered ore. It becomes possible to improve.

Example 1
FIG. 11 is a flow diagram of a granulation-sintering test apparatus under a lab-scale method consistent with the present invention. In this example, various dried sintered raw material powders were mixed in a mixer, then charged into a drum mixer, and water was added to granulate for 360 seconds. Thereafter, a part of the granulated particles was sampled, and the moisture and particle size distribution of the pseudo particles were measured. This was made into the pseudo particle diameter before drying. The remaining pseudo particles were charged into a subsequent drum mixer and granulated while introducing hot air at 300 ° C. with a hot air generator. The degree of drying was adjusted by adjusting the number of revolutions of the drum mixer and adjusting the granulation time. A portion of the pseudo particles after drying was sampled, and the moisture and particle size distribution of the pseudo particles were measured. This was set as the pseudo particle size after drying. These pseudo particles were introduced into the same sintering test apparatus as shown in FIG. 1 and subjected to a sintering test.

  FIG. 12 shows the relationship between the moisture of the pseudo particles and the arithmetic average diameter. Arithmetic mean diameter of base condition: 3.6 mm of pseudo particles having a moisture content of 8.6 to 9.3 mass% before drying, which is granulated by adding more moisture than the base condition, is the arithmetic mean diameter after drying Is 4.2 to 4.6 mm. And the thing with the water | moisture content of 10.3-11.6 mass% of the pseudo | simulation particle | grains before drying granulated by adding an excessive water | moisture content was 4.9-5.2 mm in arithmetic mean diameter after drying. In general, when the added water is equal to or higher than the appropriate water, the water is present beyond the capillary region, so that the influence of the capillary force between the particles is impaired, and the particle strength is reduced. Therefore, it is not preferable in consideration of the subsequent transport process. However, on the exit side of the drum mixer, the state of a large particle size is maintained before it is subjected to a transport impact. On the other hand, when the moisture content of the pseudo particles before drying becomes 10.3-11.6 mass%, the particle strength decreases, so that the chance of being destroyed inside the mixer increases before reaching the exit side of the drum mixer. The slope of the pseudo-particle growth line becomes smaller.

  When these pseudo particles obtained by adding water excessively are dried to appropriate moisture, the particle size of the pseudo particles increases as compared with the base condition. That is, the pseudo particles having a moisture content of 8.6 to 9.3 mass% before drying have an arithmetic average diameter of 4.2 to 4.6 mm after being dried to about 7.6 mass%. The pseudo-particles having a moisture content of 10.3 to 11.6 mass% have an arithmetic average diameter of 4.9 to 5.2 mm after drying. In short, the particle size of the pseudo particles after drying is lower than that before drying because uneven drying inevitably occurs in the mixer. This is thought to be because the fine powder peels off.

(Example 2)
This example explains the effect of the present invention when a raw material mainly composed of South American ore is used. FIG. 13 shows granulation with 7.4 mass% of moisture, which is 1.23 times the excess moisture with respect to proper granulation moisture of 6.0 mass%, and then to 6.0 mass%. The change of the arithmetic average particle diameter of the pseudo particles when dried is shown. South American ore raw materials have a small amount of proper granulation moisture because there are few pores inside the ore. Furthermore, since the adhesion between the fine particles is poor, if a large excess of water is added, the particle size of the pseudo particles no longer increases and the particle size of the pseudo particles decreases. Therefore, in this raw material, the addition of about 7.4 mass% of water was the limit for increasing the pseudo particle size. Moreover, the particle size of the pseudo particles increased after the drying step with hot air, and the effect of the present invention was confirmed.

(Example 3)
The effect of the present invention in a raw material in which pellet feed ore (-64 μm is 80% or more) with respect to Australian ore will be described. FIG. 14 shows the results when excess moisture was added to the moisture content of 10.3 mass% and 11.3 mass% with respect to the appropriate granulated moisture of 8.5 mass%. When pellet feed is blended, the amount of fine powder increases, so that the appropriate granulated moisture increases. After the drying step with hot air, the particle size of the pseudo particles increased, and the effect of the present invention was confirmed.

Example 4
In the operation of a downward suction DL sintering machine with an effective grate area of 410 m ² and a production rate of 1.5 t / h · m ² , the method for producing a sintered ore according to the present invention was tested. In this test, two drum mixers were used, granulated by adding 10.6 mass% (appropriate moisture: 1.4 times that of 7.6 mass%) to the primary drum mixer and adding the appropriate moisture. Arithmetic mean diameter of the pseudo particles obtained below: 3.2 mm is expanded to over 3.4 mm to produce pseudo particles having a large particle size, and then hot air at 300 ° C. is blown in a secondary drum mixer. The particles were dried and dried to a moisture content of 7.9 mass% corresponding to the appropriate moisture content. At this time, the average particle size of the pseudo particles was improved by about 15%, the air permeability of the sintered packed layer was improved, and the sintering production rate was improved by about 6%. From this, if the manufacturing method of the sintered ore suitable for the present invention is adopted, the air permeability of the raw material packed bed on the pallet of the sintering machine is improved, and the cold strength and yield of the sintered ore are reduced. It has been found that it is possible to improve the productivity of sintered ore without incurring the above.

  The technology of the present invention can be applied not only to the production of pseudo particles by the exemplified drum mixer, but also to the case of granulation using other granulators such as a pelletizer, and agglomeration such as pelletizing other than the sintering raw material. It can also be applied to the technology.

1 Sintering raw material 2 Mixer 3 Drum mixer 4 Butt 5 Sintering machine

Claims (12)

  Forming pseudo-particles with a water-containing fine powder layer with a particle size larger than the particle size to be formed under the proper moisture by granulating the sintering raw material powder by adding excess moisture to the proper moisture. Then, the pseudo particles having the water-containing fine powder layer are dried, and the moisture of the pseudo particles after drying is reduced to (appropriate moisture-1) mass% to (appropriate moisture + 1) mass%. A method for producing pseudo-particles for producing ores.   2. The method for producing pseudo particles for producing sinter according to claim 1, wherein the appropriate moisture is moisture that maximizes the air permeability of the raw material packed layer filled with the pseudo particles.   The method for producing pseudo-particles for producing sinter according to claim 1, wherein the excess moisture is 1.1 to 1.5 times as much as appropriate moisture. The method for producing pseudo-particles for sinter ore production according to claim 3, wherein the excess moisture is 1.25 to 1.5 times as much as the appropriate moisture.   The method for producing pseudo-particles for producing sinter according to claim 4, wherein the excess water is 1.3 to 1.45 times as much as the appropriate water.   2. The baked powder according to claim 1, wherein the pseudo-particle having a particle size larger than the particle size formed under the appropriate moisture has a hydrous fine powder layer composed of moisture and agglomerated fine powder on the outside thereof. A method for producing pseudo-particles for producing ores.   The said drying is a drying process which makes the water | moisture content of the pseudo-particles after drying the water | moisture content of appropriate water mass%-(appropriate water +0.5) mass%. Method. By granulated with the addition of excess water than the proper moisture sintering raw material powder, the particle size larger than the particle size to be formed under該適positive moisture, the pseudo particles having a water fine layer formed And
The pseudo particles having the water-containing fine powder layer are dried, and the moisture of the pseudo particles after drying is reduced to (appropriate moisture-1) mass% to (appropriate moisture + 1) mass%,
And the pseudo particles with reduced moisture are charged into a sintering machine and sintered.
The manufacturing method of the sintered ore characterized by the above-mentioned.   The method for producing a sintered ore according to claim 8, wherein the appropriate moisture is moisture that maximizes the air permeability of the raw material packed layer filled with pseudo particles.   The method for producing a sintered ore according to claim 8, wherein the excessive moisture is 1.1 to 1.5 times as much as appropriate moisture.   The method for producing a sintered ore according to claim 10, wherein the excessive moisture is 1.25 to 1.5 times as much as appropriate moisture.   The method for producing a sintered ore according to claim 11, wherein the excessive moisture is 1.3 to 1.45 times as much as appropriate moisture.