JP7147505B2 - Method for producing sintered ore - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sintered ore production method capable of producing sintered ore with a high yield.

In general, sintered ore consists of sintering raw materials (main raw material iron ore [powder], secondary raw materials limestone, quicklime, peridotite, etc., fuel [carbon material] coke, anthracite, etc., miscellaneous raw material scales, etc., and Return ore, ) is mixed and granulated, the granulated pseudo-particles are charged into a sintering machine, and after igniting the fuel on the surface layer, it is sintered by downward ventilation.

In the firing process of the sintering raw material (pseudo-particles), the sintering raw material is heated to around 1300°C by the combustion heat of the fuel (coke fine, anthracite, etc.). A melt is formed, and the amount of melt increases as the temperature rises, finally forming a binder phase between the coarse-grained iron ores.

The quality and yield of sintered ore basically depend on the quality of iron ore (powder), but in fact, the amount of binder phase generated in the sintering process, the degree of spreading, and / or bonding heavily influenced by mode. In order to increase the strength of the sintered ore, in the firing process of the sintered raw material, the fuel (carbonaceous material) in the sintered raw material is efficiently burned in a piled state in which the pseudo-particles are in close contact with each other. A bonded phase must be formed.

In order to realize the above-mentioned combustion that enhances the quality and yield of sintered ore, the aspect of pretreatment consisting of blending, mixing, and granulation of sintering raw materials is important. A number of methods for producing improved sintered ore have been disclosed.

For example, in Non-Patent Document 1, a mixer for mixing sintering raw materials has two stages, in the first stage, coke mainly composed of fine powder is added as part of the coke, and in the second stage, the granulation time is 40. A pretreatment technique (coke split addition method) is disclosed in which coarse-grained coke (5 to 20% of total coke) is added as the remaining coke at 10% (intermediate). This technique improves yield and doubles productivity.

In Patent Document 1, in the production of sintered ore using anthracite as part of the fuel for sintering, prior to mixing the anthracite with other sintering raw materials, the anthracite and sintered ore of 5 mm or less are mixed. A method of using anthracite coal as a fuel for sintering is disclosed, characterized by mixing. According to the method for using anthracite coal of Patent Document 1, it is possible to easily handle the anthracite coal, which is sticky and dust-generating.

Patent Document 2 describes a method for producing sintered ore in which coke fines and anthracite are blended with sintering raw materials, mixed and granulated, charged into a sintering machine and fired, in which coke fines are coarsely ground. The particle size is adjusted to 80 wt% or more from 0 to 5.0 mm, and the anthracite is finely pulverized to have a particle size of 80 wt% or more from 0 to 2.0 mm and blended in the sintering raw material. A method for producing sintered ore is disclosed.

According to the production method of Patent Document 2, the product yield of sintered ore can be improved, and the NOx emission can be suppressed.

Patent Document 3 discloses a method for granulating a raw material for sintering by mixing and granulating a powdered iron source, a powdered carbonaceous material, and fine limestone in a drum mixer, wherein the powdered iron source is fed from a feed section of the drum mixer. is charged and granulated, and the powdery carbonaceous material and A method of granulating a sintering raw material (particle size change rate = (d - D _I )/(D _O −D _I ) (1) d: Average particle size of pseudo-particles at any position in the drum mixer (mm) D _I : Average particle size of powdered iron source in feed section (mm ) D _O : Average grain size (mm) of three-layer pseudo-grains in the ore discharge zone.

According to the granulation method of Patent Document 3, the pseudo-particles of the sintering raw material can be granulated by simple means at low cost, and the RI value (%) and productivity of the sintered ore are improved.

In Patent Document 4, iron ore, SiO ₂ -containing powder raw material, limestone-based powder raw material and solid fuel-based powder are used as pretreatment for the process of producing sintered ore for blast furnace using a downward suction Dwight Lloyd sintering machine. When granulating the sintered raw material made of raw materials using a drum mixer, the sintered raw material excluding the solid fuel system powder raw material is charged from the charging port of the drum mixer and granulated, and the solid fuel system Adding the solid fuel-based powdered raw material in a region set in the middle of the downstream side where the residence time until the sintered raw material excluding the powdered raw material reaches the discharge port of the drum mixer satisfies 10 to 120 seconds, A method for producing a raw material for sintering is disclosed, which is characterized in that the powdery solid fuel-based raw material is adhered to and formed on an exterior portion of the raw material for sintering before reaching the discharge port.

According to the production method of Patent Document 4, the productivity of sintered ore is improved.

Patent Document 5 discloses a method for granulating a sintering raw material for iron making in the presence of coke fine and/or anthracite coal, wherein the granulation treatment method for the sintering raw material for iron making includes coke fine and/or anthracite coal. is subjected to hydrophobic treatment with an aqueous emulsion of a hydrophobic substance, and then the fuel after the hydrophobic treatment is granulated with part or all of the remaining sintering raw material for ironmaking. Disclosed is a method of granulating sintering raw materials for sintering.

According to the granulation treatment method of Patent Document 5, the granulation properties of the raw material for sintering are improved, the ignitability and combustibility are improved, and the productivity of sintered ore is improved.

JP-A-10-176228 JP-A-10-298670 JP-A-2002-285250 Japanese Patent Application Laid-Open No. 2003-160815 JP 2009-275270 A

Steel Research, No. 288 (1976), pp. 11797-11806

Anthracite has a low N content and is an effective fuel (charcoal material) in terms of suppressing the generation of NOx. There are few pretreatment technologies for sintering raw materials that are used as (see Patent Documents 1 and 2), and when coke and anthracite are used together as fuel (carbon material), anthracite that can increase the yield of sintered ore No useful knowledge regarding the blending / addition of is found.

Therefore, in view of the current state of the prior art, the present invention provides a method for producing sintered ore by firing sintering raw materials that are granulated using both coke and anthracite coal as fuel (carbon material). It is an object of the present invention to find a suitable addition technique to increase the yield of sintered ore, and to provide a method for producing sintered ore that solves the problem.

The present inventors diligently studied methods for solving the above problems. As a result, as a carbonaceous material to be added to the sintering raw material, a part or all of anthracite used in combination with coke is added to the sintering raw material during granulation, and then granulated and fired to obtain coarse iron ore. It was found that a strong binding phase could be formed between them, and the yield of sintered ore was improved.

The present invention was made based on the above findings, and the gist thereof is as follows.

(1) In a method for producing sintered ore in which a sintering raw material granulated using both coke and anthracite as main carbon materials is fired,
(i) In the granulated sintering raw material, the total amount of coke and anthracite is 90% by mass or more based on the total carbon material, and the amount of anthracite is 20 to 40% by mass based on the total carbon material. and
(ii) In the process of granulating the raw material for sintering, 1/2 to the total amount of anthracite coal to be added in an amount of 20 to 40 % by mass based on the total carbon material is added by the following formula ( A method for producing a sintered ore, characterized by adding to a sintering raw material during granulation at a time Tx that satisfies 1), and further granulating.
0.45≤Tx/Tf≤0.60 (1)
Tx: Time from start of granulation to addition of anthracite (minutes)
Tf: Time from start of granulation to end of granulation (minutes)

(2) The method for producing sintered ore according to (1) above, wherein the anthracite has an average particle size of 1.5 to 1.8 mm.

According to the present invention, since a firm binding phase can be formed between coarse-grained iron ores, the yield of sintered ore is improved.

FIG. 4 is a diagram schematically showing a mode of adding anthracite to the sintering raw material during granulation, mixing and granulating the sintering raw material, and firing the sintering raw material. FIG. 4 is a diagram schematically showing another embodiment in which anthracite coal is added to the sintering raw material during granulation, mixed, granulated, and fired when the sintering raw material is granulated.

In the method for producing sintered ore of the present invention (hereinafter sometimes referred to as "the production method of the present invention"), part or all of anthracite used in combination with coke is added as a carbonaceous material to the sintering raw material during granulation. The basic idea is to add it to the sintering raw material, and specifically, in the method for producing sintered ore in which the sintering raw material is granulated using both coke and anthracite as the main carbon material,
(i) In the granulated sintering raw material, the total amount of coke and anthracite is 90% by mass or more based on the total carbon material, and the amount of anthracite is 20 to 40% by mass based on the total carbon material. and
(ii) In the process of granulating the raw material for sintering, 1/2 to the total amount of anthracite coal to be added in an amount of 20 to 40 % by mass based on the total carbon material is added by the following formula ( It is characterized in that it is added to the sintering raw material during granulation at the time Tx that satisfies 1), and is further granulated.
0.45≤Tx/Tf≤0.60 (1)
Tx: Time from start of granulation to addition of anthracite (minutes)
Tf: Time from start of granulation to end of granulation (minutes)

Further, the production method of the present invention is characterized in that the anthracite has an average particle size of 1.5 to 1.8 mm.

The production method of the present invention will be described below.

Raw materials for sintering (pseudo-particles) include iron ore [powder] as the main raw material, limestone, quicklime, peridotite, etc. as secondary raw materials, coke, anthracite, etc. as fuel [carbon material], scales as miscellaneous raw materials, and return ore. are blended at a predetermined ratio and granulated. The raw material for sintering (pseudo-particles) is fired under normal firing conditions.

Table 1 shows a blending example of the sintering raw material (pseudo-particles).

The return ore is a powdery sintered ore that is unsuitable as a raw material for blast furnaces and is obtained under a sieve after pulverizing and sizing the sintered ore. Carbonaceous materials are mainly coke and anthracite. Miscellaneous heat sources other than coke and anthracite are, for example, CDQ powder and carbon-containing dust.

The mixing ratio of return ore and carbonaceous material is usually indicated by the outside number of (main raw material + auxiliary raw material). The mixing ratio of the return ore and the carbon material is appropriately set according to the amount and composition of (main raw material + auxiliary raw material) and the firing conditions. The carbonaceous material is 2.5-5.0% by mass.

The particle size of coke is not particularly limited to a specific range, but it is necessary to ensure sufficient combustion heat in the sintering raw material (pseudo-particles), and without hindering the granulation of iron ore (raw material). Considering maintenance, an average particle size of 1.5 to 2.0 mm is preferable. The particle size of the anthracite coal is not particularly limited to a specific range, but considering that it is added to the sintering raw material during granulation to uniformly adhere the anthracite coal to the surface layer of the sintering raw material (pseudo-particles), the average particle size is is preferably 1.5 to 1.8 mm.

The particle size of the granulated sintering raw material (pseudo-particles) is not particularly limited to a specific range, but the sintering machine ensures the air permeability of the deposited sintering raw material layer and ensures heat transfer of combustion heat. Considering this, the average particle size is preferably 2 to 5 mm.

The average particle size is an average value calculated by weighting the median value of each particle size category by the mass fraction of each particle size category.
In the production method of the present invention, the total amount of coke and anthracite coal is 90 mass % or more based on the total carbon material, and the amount of anthracite coal is 20 to 40 mass % based on the total carbon material. Preferably, the total amount of coke and anthracite is at least 95% by weight and the amount of anthracite is between 23 and 37% by weight. The reason for limiting the total amount of coke and anthracite and the reason for limiting the amount of anthracite will be described later.

Next, the feature of the production method of the present invention (addition of anthracite during granulation) will be described with reference to the drawings.

FIG. 1 schematically shows a mode in which anthracite coal is added to the sintering raw material during granulation, mixed, granulated, and fired during granulation of the sintering raw material.

In FIG. 1, coke is stored in the coke tank 1, anthracite is stored in the anthracite tank 2, and iron ore, limestone, quicklime, peridotite, and other raw materials are individually stored in the raw material tank 4, The carbon material tank 3 stores carbon materials other than coke and anthracite (miscellaneous heat sources: CDQ powder, carbon-containing dust, for example).

A predetermined amount of sintering raw material X cut out and blended from the coke tank 1, the raw material tank 4, and optionally from the carbon material tank 3 and/or the anthracite tank 2 is conveyed to the granulator 5, and the required amount of water, binder, etc. is added and granulated, and finally, as a sintering raw material (pseudo-particles) to be fired in the sintering machine 6, (a) the total amount of coke and anthracite is 90% by mass or more of the total carbon material and (b) a sintering raw material (pseudo-particles) Y containing 20 to 40% by mass of anthracite with respect to the total carbonaceous material.

The granulator 5 may be any granulator having a function of granulating the raw material for sintering, and is not limited to the drum-type granulator. good.

Then, when granulating the sintering raw material X with the granulator 5, 1/2 to the entire amount of anthracite added to the sintering raw material at a rate of 20 to 40% by mass with respect to the total carbon material. After the start of granulation, it is added at time Tx satisfying the following formula (1), and granulated. This point is a feature of the production method of the present invention, and the addition of this anthracite during granulation improves the yield of sintered ore.
0.45≤Tx/Tf≤0.60 (1)
Tx: Time from start of granulation to addition of anthracite (minutes)
Tf: Time from start of granulation to end of granulation (minutes)

Here, at the time of starting granulation, the sintering raw material X mixed with the required raw materials is conveyed to the granulator 5, water is added, the granulator 5 is operated, and the sintering raw material X is produced. It is the time to start granulation, and the time to end granulation is the time to discharge the sintering raw material (pseudo-particles) Y from the granulator 5 after the granulation of the sintering raw material X is completed.

In the granulation of the raw material for sintering using one sintering machine 5, the granulation time is from the start of granulation to the end of granulation, which is usually 3 to 6 minutes.

The total amount of coke and anthracite coal in the raw material for sintering, the amount of anthracite coal, and the amount and timing of adding anthracite to the raw material for sintering during granulation will be described later.

FIG. 2 schematically shows another embodiment in which anthracite coal is added to the sintering raw material during granulation, mixed, granulated, and fired when the sintering raw material is granulated. The granulation mode shown in FIG. 2 is a mode in which the raw material for sintering is granulated by two granulators arranged in series.

In FIG. 2, coke is stored in the coke tank 1, anthracite is stored in the anthracite tank 2, and iron ore, limestone, quicklime, peridotite, and other raw materials are individually stored in the raw material tank 4, The carbon material tank 3 stores carbon materials other than coke and anthracite (miscellaneous heat sources: CDQ powder, carbon-containing dust, for example).

A predetermined amount of sintering raw material X cut out and blended from the coke tank 1, the raw material tank 4, and optionally from the carbon material tank 3 and/or the anthracite tank 2 is conveyed to the granulator 5a, and the required amount of water, binder, etc. is added to granulate. Then, to the sintering raw material Ya discharged from the granulator 5a, from the anthracite tank 2, (1/2 to the whole amount) of the total amount of anthracite (20 to 40% by mass of the total carbon material) is added to the granulator. Add between 5a and granulator 5b.

The sintering raw material Ya to which the required amount of anthracite is added is conveyed to the granulator 5b, and if necessary, the required amount of water, binder, etc. are added and further granulated, and finally the sintering machine As the sintering raw material (pseudo-particles) to be fired in 6, (a) the total amount of coke and anthracite coal is 90% by mass or more of the total carbon material, and (b) the amount of anthracite coal is 20 to 40% by mass of sintering raw material (pseudo-particles) Yb is produced.

The granulator 5a and the granulator 5b may be any granulator having a function of granulating the raw material for sintering. A type granulator may be used, or the granulator 5a and the granulator 5b may be different types of granulators.

Then, when the sintering raw material X is granulated by the granulator 5a and the granulator 5b, the amount of anthracite finally added to the sintering raw material at a rate of 20 to 40 mass with respect to the total carbon material is 1/2 to the entire amount is added at the time Tx satisfying the following formula (1) after the start of granulation, and granulation is further performed. As described above, this point is a feature of the production method of the present invention, and the addition of this anthracite during granulation improves the yield of sintered ore.
0.45≤Tx/Tf≤0.60 (1)
Tx: Time from start of granulation to addition of anthracite (minutes)
Tf: Time from start of granulation to end of granulation (minutes)

Here, at the start of granulation, the sintering raw material X mixed with the required raw materials is conveyed to the granulator 5a, water is added, the granulator 5a is operated, and the sintering raw material X is produced. This is the time to start granulation, and the time to finish granulation is when the sintering raw material Ya granulated by the granulator 5a is conveyed to the granulator 5b, water is added as appropriate, and the granulator 5b is turned off. This is the time when the sintering raw material Ya is further granulated, and the sintering raw material Ya is discharged from the granulator 5 as the sintering raw material (pseudo-particles) Yb.

In the granulation of the sintering raw material using the two sintering machines 5a and 5b, the granulation time in the first sintering machine 5a and the granulation time in the second sintering machine 5b is the substantial total granulation time, which is usually 3 to 6 minutes.

When the raw material for sintering is granulated in the granulation mode shown in FIG. 2, Tx and Tf are specifically as follows.
Tx: (granulation time in granulator 5a)
Tf: (granulation time in granulator 5a) + (granulation time in granulator 5b)

In the granulation of the sintering raw material, FIG. 1 shows the case of granulating using one granulator, and FIG. 2 shows the case of granulating using two granulators. , The number of granulators is not limited to one or two. Three or more sintering machines may be used for granulating the raw material for sintering. Even in this case, the sum of the granulation times of all the granulators is Tf, the first granulator is the starting point, and the sum of the granulation times of the granulators until anthracite is added in the middle is Tx. (1) can be applied.

In the production method of the present invention, as a carbon material to be added to the sintering raw material, part or all of anthracite used in combination with coke is added to the sintering raw material during granulation, and then granulated and fired to obtain sintered ore The reason why the quality and yield are improved is presumed as follows.

When the anthracite coal is attached around the sintering raw material (pseudo-particles), the granulation of the sintering raw material (pseudo-particle size) is improved compared to the state in which the anthracite is uniformly dispersed throughout the sintering raw material (pseudo-particles). A strong sintered raw material (pseudo-particles) is formed. In the sintering raw material layer charged with this sintering raw material (pseudo-particles), the amount of fine powder is reduced, and air permeability is appropriately ensured.

Furthermore, since the anthracite exists around the sintering raw material (pseudo-particles), it has good contact with oxygen. A strong bonding phase is formed between the granular iron ores.

Next, the total amount of coke and anthracite coal in the raw material for sintering, the amount of anthracite coal, and the amount and time of addition of anthracite during granulation of the raw material for sintering will be described.

First, the total amount of coke and anthracite in the sintering raw material and the amount of anthracite will be explained.

Total amount of coke and anthracite coal: 90 mass% or more of all carbon materials From the required amount of iron ore, limestone, quicklime, peridotite, other raw materials, and the required amount of carbon materials (coke, anthracite, other carbon materials) In the raw material for sintering, the total amount of coke and anthracite is set to 90% by mass or more with respect to the total carbonaceous material.

When the sintering raw material (pseudo-particles) is fired, the carbonaceous material burns to heat the sintering raw material (pseudo-particles) and contributes to the formation of the binder phase necessary to secure the strength of the sintered ore. If the total amount of anthracite is less than 90% by mass with respect to the total carbonaceous material, sufficient combustion heat cannot be obtained, and the amount of binder phase required to secure the strength of the sintered ore cannot be formed. and anthracite should be 90% by mass or more of the total carbonaceous material. It is preferably 95% by mass or more, and the upper limit is 100% by mass.

Amount of anthracite: 20 to 40% by mass of the total carbon material
Anthracite has a low N content and is therefore a preferable carbonaceous material, but its combustibility is lower than that of coke, so there is an upper limit to the amount used. If the amount of anthracite is less than 20% by mass relative to the total carbonaceous material, the amount of NOx in the exhaust gas increases. Preferably, it is 23% by mass or more.

On the other hand, if the amount of anthracite exceeds 40% by mass based on the total carbonaceous material, the firing rate of the sintering raw material (pseudo-particles) is delayed, and sufficient combustion heat cannot be secured in the surface layer of the pseudo-particles, resulting in sintering. The amount of anthracite coal is set to 40% by mass or less with respect to the total carbonaceous material because it is difficult to form the binder phase necessary to ensure the strength of the ore. Preferably, it is 37% by mass or less.

Next, the reasons for limiting the amount and time of addition of anthracite to the sintering raw material (pseudo-particles) during granulation will be explained.

Amount of anthracite added during granulation: 1/2 to whole amount of 20 to 40 mass of anthracite in total carbon material The amount is 20 to 40% by mass with respect to the total carbonaceous material, and 1/2 to the whole amount of the amount (20 to 40% by mass) is added to the sintering raw material (pseudo-particles) during granulation. are added at time points (see Figures 1 and 2).

If the total amount of anthracite is not added to the sintering raw material during granulation, 20 to 40% by mass of the total carbon material (1/2 to the total amount) Less than anthracite coal (the amount of anthracite not added during granulation) is added in advance to the sintering raw material before being supplied to the granulator.

If the amount of anthracite added to the sintering raw material (pseudo-particles) during granulation is less than 10% by mass (=20% by mass/2), the amount of anthracite attached around the sintering raw material (pseudo-particles) In the sintering raw material layer where the sintering raw material (pseudo-particles) is charged, air permeability cannot be properly secured, and high combustion heat is obtained in the surface layer and inside of the sintering raw material (pseudo-particles) during firing. can't

As a result, a strong bonding phase is not sufficiently formed between coarse-grained iron ores, and the yield of sintered ore is not improved. 10% by mass (=20% by mass/2) or more. Preferably, it is 15% by mass or less.

Time point at which anthracite coal is added during granulation: Tx time point satisfying the following formula (1): 0.45 ≤ Tx/Tf ≤ 0.60 (1)
Tx: Time from start of granulation to addition of anthracite (minutes)
Tf: Time from start of granulation to end of granulation (minutes)

The addition of 20 to 40% by mass (1/2 to the total amount) of anthracite to the total carbonaceous material to the sintering raw material during granulation (see FIGS. 1 and 2) is based on the above formula (1). It is done at the Tx time point that satisfies.

If the anthracite coal is added when Tx/Tf is less than 0.45, the anthracite coal is added when the shape of the pseudo-particles is not stable. Since the shape of the particles is difficult to stabilize, anthracite should be added at a time when Tx/Tf is 0.45 or more. Preferably, it is the time when Tx/Tf is 0.48 or more.

On the other hand, when the anthracite coal is added when Tx/Tf exceeds 0.60, the anthracite coal is added when the shape of the pseudo-particles is stable. is difficult to adhere evenly, the anthracite should be added when Tx/Tf is 0.60 or less. Preferably, it is the time when Tx/Tf is 0.57 or less.

Next, examples of the present invention will be described. The conditions in the examples are one example of conditions adopted for confirming the feasibility and effect of the present invention, and the present invention is based on this one example of conditions. It is not limited. Various conditions can be adopted in the present invention as long as the objects of the present invention are achieved without departing from the gist of the present invention.

(Example 1)
Anthracite is added to the granulated sintering raw material (pseudo-particles) and the sintering raw material in the middle of granulation by changing the addition time and amount, and further granulated sintering raw material (pseudo-particles) A sintering pot test was carried out for and the yield of sintered ore was measured.

In the sintering pot test, a cylindrical sintering pot is filled with sintering raw materials, the surface of the raw material packed layer in the sintering pot is ignited, and then air is blown by a blower from a wind box installed at the bottom of the sintering pot. This test simulates the firing process of the sintered raw material layer in an actual machine by sucking and firing the raw material packed layer.

(Granulation of sintering raw material)
Table 1 shows the composition of the sintering raw materials used. Here, the sum of coke, anthracite, and CDQ powder was set to 3.6% by mass (fixed) as an external number based on the blended raw materials, and the respective blending ratios were changed as shown in Table 3.

The sintering raw material blended at the required blending ratio is charged into a drum-type granulator with a diameter of 1 m, and after granulating for a predetermined time with a target moisture content of 7.5%, anthracite is added at the addition time shown in Table 3. and added amount, and further granulated. Total granulation time is 4 minutes. CDQ powder was used as a miscellaneous heat source.

(Sintering pot test device)
Table 2 shows the specifications and test conditions of the test equipment used in the sintering pot test.

(Yield measurement)
The sintered body fired in the sintering pot is dropped 2 m × 4 times and crushed, and the collected sintered body (sintered ore) is classified with a sieve mesh of 5 mm, and the sieved (sintered ore) and the sieved ( The mass of return ore) was measured, and the yield of sintered ore (over sieve) was calculated by the following formula.

Yield (%) = 100 x (5 mm above sieve) / [(5 mm above sieve) + (5 mm below sieve)]
The results are also shown in Table 3.

The conventional example is an example in which the raw material for sintering shown in Table 1 (charcoal material: 3.6% by mass as an external number) was granulated and fired. The yield of sintered ore remains at 86.4%.

In Invention Example 1, as a carbonaceous material, 0.72% by mass of external number was added to the sintering raw material in the middle of granulation, which was blended with 2.70 (= 3.6 0.75)% by mass of external number. (= 3.6 0.20, 20% by mass with respect to the total carbon material) of anthracite was added at the time when Tx/Tf satisfies the above formula (1), and was further granulated and fired. This is an example of adding the entire amount in the middle. The effect of adding anthracite coal during granulation is fully manifested, and the yield of sintered ore is 87.4%.

In Invention Example 8, as a carbonaceous material, 1.98 (= 3.6 0.55) mass% of coke alone was blended in the sintering raw material during granulation, and 1.44 mass% of the external number was added. (= 3.6 0.40, 40% by mass with respect to the total carbonaceous material) of anthracite was added in its entirety at the point where Tx/Tf satisfies the above formula (1), and then granulated and fired. This is an example of adding the entire amount in the middle. The effect of adding anthracite coal during granulation is fully manifested, and the yield of sintered ore is 87.1%.

In Comparative Example 3, only coke as a carbonaceous material was blended with 1.58 (= 3.6 0.44) mass% of the external number in the sintering raw material during granulation, and 1.80 mass% of the external number was added. (= 3.6 0.50, 50% by mass of the total carbonaceous material) of anthracite was added in its entirety at the time of addition where Tx/Tf satisfies the above formula (1), then granulated and fired. This is an example of adding the entire amount in the middle. Since the amount of anthracite coal is 50% by mass with respect to the carbonaceous material, and it exceeds 40% by mass, the effect of adding anthracite coal during granulation is not sufficiently exhibited, and the yield of sintered ore remains at 86.0%. there is

In invention examples 2 to 7 and 9 and comparative examples 1, 2 and 4, a part of anthracite added as a carbonaceous material to the sintering raw material was added to the sintering raw material during granulation, and further This is a “partially added example” of granulating and baking.

In Invention Example 2, as the carbonaceous material, coke is 2.70 (= 3.6 0.75) mass% in external number, and anthracite is 0.36 (= 3.6 0.10) in external number. 10% by mass of the total carbonaceous material (1/2 of 20% by mass of the carbonaceous material, 0.0% by mass of the sintering raw material) 36% by mass) of anthracite was added at the point of addition of 0.45 at which Tx/Tf satisfies the above formula (1), and then granulated and fired.

In Invention Example 3, as the carbonaceous material, coke is 2.34 (= 3.6 0.65) mass% in external number, and anthracite is 0.36 (= 3.6 0.10) in external number. 20% by mass of the total carbonaceous material (2/3 of 30% by mass of the carbonaceous material, 0.0% by mass of the sintering material) 72% by mass) of anthracite was added at the point of addition of 0.50 where Tx/Tf satisfies the above formula (1), and then granulated and fired.

In Invention Example 4, as the carbonaceous material, coke is 2.34 (= 3.6 0.65) mass% in external number, and anthracite is 0.54 (= 3.6 0.15) in external number. 15% by mass of the total carbonaceous material (1/2 of 30% by mass of the carbonaceous material, 0.0% by mass of the sintering raw material) 54% by mass) of anthracite was added at the point of addition of 0.50 where Tx/Tf satisfies the above formula (1), and then granulated and fired.

In all of Invention Example 2, Invention Example 3, and Invention Example 4, the amount of anthracite coal added midway and the point of time of midway addition are within the scope of the present invention, so the effect of adding anthracite coal midway through granulation is sufficient. Expressed, the yield of sintered ore exceeds 87.0%.

In Invention Examples 5, 6, and 7, as carbonaceous materials, coke is 1.98 (= 3.6 0.55) mass% in terms of the outside number, and anthracite is 0.72 in the outside number. (= 3.62 0.2) 20% by mass of the total carbonaceous material (1/2 of 40% by mass of the carbonaceous material, sintering raw material 0.72% by mass as an external number) of anthracite at the time when Tx / Tf satisfies the above formula (1) (Invention Example 1: 0.45, Invention Example 2: 0.50, and Invention Example 3: 0.60, all within the range of 0.45 to 0.60), granulated, and fired.

In all of Invention Example 5, Invention Example 6, and Invention Example 7, the amount of anthracite coal added during granulation and the timing of addition during the process are within the scope of the present invention, so the effect of adding anthracite coal during granulation is sufficient. Expressed, the yield of sintered ore exceeds 87.0%. In particular, in invention example 2 where the addition time points Tx/Tf are 0 and 50, the yield of sintered ore reaches 87.2%.

Inventive Example 9 is a "partially added example" in which the distribution of carbonaceous materials and the point of addition are the same as in Inventive Example 2, but the average grain size of anthracite coal is refined to 1.7 μm. Since the average particle size of the anthracite coal was refined, the effect of adding the anthracite coal during the granulation process was more pronounced, and the yield of the sintered ore reached 87.5%.

In Comparative Examples 1 and 2, as the carbon material, coke was 1.98 (=3.6 0.55) mass% in terms of the external number, and anthracite was 0.72 (=3. 6.0.2) 20% by mass of the total carbonaceous material (1/2 of 40% by mass of the carbonaceous material, 1/2 of 40% by mass of the carbonaceous material, 0.72% by mass in terms of external number) of anthracite at the time when Tx / Tf satisfies the above formula (1) (Invention Example 1: 0.45, Invention Example 2: 0.50, and Invention Example 3: 0.60, all within the range of 0.45 to 0.60), and then granulated and fired.

In Comparative Example 1, Tx/Tf is 0.30 (less than 0.45), which does not satisfy the above formula (1), so the effect of adding anthracite coal during granulation is not sufficiently exhibited, and sintered ore The yield remains at 86.5%. In Comparative Example 2, Tx/Tf is 0.70 (exceeding 0.60), which does not satisfy the above formula (1). The yield remains at 86.5%.

In Comparative Example 4, as the carbon material, coke was 1.98 (= 3.6 0.55) mass% in terms of the external number, and anthracite was 1.12 (= 3.6 0.31) in the external number. 20 mass% of the total carbonaceous material (3/5 of 31 mass% of the carbonaceous material, 0.72 ( = 3.6 0.20) mass% of anthracite was added at the addition point of 0.50 (within the range of 0.45 to 0.60 of the present invention) at which Tx/Tf satisfies the above formula (1). This is a “partially added example” in which the powder is further granulated and baked.

In Comparative Example 4, the amount of miscellaneous heat sources is 14% by mass, the total amount of coke and anthracite is 86% by mass, and the total amount of coke and anthracite is less than 90% by mass. Therefore, the effect of adding anthracite coal during granulation is not sufficiently exhibited, and the yield of sintered ore remains at 85.9%.

As described above, according to the present invention, a strong binding phase can be formed in the entire sintered ore, so the quality and yield of the sintered ore are improved. Therefore, the present invention has high applicability in the steel industry.

REFERENCE SIGNS LIST 1 coke tank 2 anthracite coal tank 3 carbon material tank 4 raw material tank 5, 5a, 5b granulator 6 sintering machine X sintering raw material Y sintering raw material (pseudo-particles)
Ya sintering raw material (pseudo-particles)
Yb sintering raw material (pseudo-particles)

Claims (1)

In a method for producing sintered ore in which a sintering raw material granulated using both coke and anthracite as main carbon materials is fired,
(i) In the granulated sintering raw material, the total amount of coke and anthracite is 90% by mass or more based on the total carbon material, and the amount of anthracite is 20 to 40% by mass based on the total carbon material. and
(ii) In the process of granulating the raw material for sintering, 1/2 to the total amount of anthracite added to the total carbon material in an amount of 20 to 40% by mass is added by the following formula (1 ) is added to the sintering raw material during granulation at the time Tx to satisfy ), and is further granulated ,
(iii) the anthracite has an average particle size of 1.5 to 1.8 mm;
A method for producing sintered ore, characterized by:
0.45≤Tx/Tf≤0.60 (1)
Tx: Time from start of granulation to addition of anthracite (minutes)
Tf: Time from start of granulation to end of granulation (minutes)

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