阅读说明：本技术 烧结矿的制造方法 (Method for producing sintered ore ) 是由 竹原健太 山本哲也 广泽寿幸 石井邦彦 渡边宗一郎 泷川洋平 半田英司 于 2018-07-03 设计创作，主要内容包括：提供一种除去局部性地强度低的部分并提高整体的强度的烧结矿的制造方法。烧结矿的制造方法向一次破碎后的烧结矿(1)施加冲击力(步骤S103),然后,对被施加了冲击力的烧结矿(1)进行筛选(步骤S104)。(Provided is a method for producing a sintered ore, wherein a part having locally low strength is removed and the strength of the whole is improved. The method for producing sintered ore applies an impact force to the sintered ore (1) after primary crushing (step S103), and then screens the sintered ore (1) to which the impact force is applied (step S104).)

1. A method for producing a sintered ore,

and applying an impact force to the once crushed sintered ore, and screening the sintered ore to which the impact force is applied.

2. The method of manufacturing sintered ore according to claim 1,

the impact force is applied to the sintered ore by a dropping method or a drum method.

3. The method of manufacturing sintered ore according to claim 2,

the falling height of the sintered ore in the falling method is 0.5m to 2.0 m.

4. The method of producing sintered ore according to claim 2 or 3,

the dropping method is a method of dropping the sintered ore plural times.

5. The method of producing sintered ore according to any one of claims 1 to 4,

the impact force is applied one or more times, the sintered ore is classified before at least one of the impact forces is applied, and only the undersize sintered ore is subjected to the impact force, so that the undersize sintered ore to which the impact force is applied is mixed with the oversize sintered ore.

6. The method of manufacturing sintered ore according to claim 2,

the drum method is a method in which the sintered ore is put into a drum and subjected to rotation treatment.

7. The method of manufacturing sintered ore according to claim 6,

the inner diameter of the rotary drum is more than 1m and less than 4 m.

Technical Field

The present invention relates to a method for producing a sintered ore for the purpose of improving the strength of a sintered ore as a blast furnace raw material.

Background

A blast furnace used in the iron making industry is an apparatus that uses lump ore or sintered ore as an iron source, and melts and reduces the iron source by charging a blast furnace raw material containing the iron source from the upper portion and blowing a reducing gas from the lower portion. In order to promote the reaction between the reducing gas and the iron source, the gas in the blast furnace needs to flow in a sufficient amount, and it is important to improve the productivity of molten iron and to reduce the cost when the gas permeability in the furnace is improved.

In order to improve the air permeability in the blast furnace, it is necessary to suppress the powder rate (5mm or less) of the blast furnace raw material, and it is intended to use a high-strength blast furnace raw material for the purpose of reducing the powder rate. Therefore, various methods have been carried out to improve the strength of the sintered ore as the main raw material.

As a method for producing a sintered ore for improving the strength of the sintered ore, for example, a method shown in patent document 1 is known.

The method for producing sintered ore disclosed in patent document 1 is a method for producing sintered ore by supplying various gaseous fuels from above a charged layer of sintering material deposited on a pallet of a sintering machine, wherein a gaseous fuel diluted to a lower-limit-of-combustion concentration or less is used as the gaseous fuel supplied from above the charged layer on the pallet, and when sintering is performed by supplying the gaseous fuel, the supply position, the maximum arrival temperature of the charged layer, or the holding time in a high-temperature region are adjusted to be at least one of the above.

With this method for producing sintered ore, during the operation of the downward suction type sintering machine, the diluted gaseous fuel is supplied to the charged layer, so that deterioration in the air permeability of the entire charged layer is avoided, and sintered ore having high strength can be produced with high yield.

As another example of a method for producing sintered ore for improving the strength of sintered ore, a method shown in patent document 2, for example, has been known in the past.

The method for producing sintered ore shown in patent document 2 is a method for producing sintered ore using high crystal water ore as a raw material, wherein dolomite is used as a sintering auxiliary raw material as an MgO source, and the dolomite is preferentially distributed to the lower layer of the pallet of the sintering machine and fired.

As another example of a method for producing sintered ore for improving the strength of sintered ore, a method shown in patent document 3, for example, has been known in the past.

In the method for supplying sintered ore to a blast furnace disclosed in patent document 3, impact energy of 200 to 600J/kg in total is applied to a conveying path of the sintered ore from an ore discharge portion of a sintering machine to charging into the blast furnace in advance or in 1 or more times in the middle of the conveying path, and then the sintered ore is classified.

Prior art documents

Patent document

Patent document 1: japanese patent laid-open No. 2008-95170

Patent document 2: japanese patent laid-open publication No. 2000-336434

Patent document 3: japanese patent laid-open publication No. 2000-336434

Disclosure of Invention

Problems to be solved by the invention

However, sintered ores produced by the methods for producing sintered ores described in the above-described conventional patent documents 1 and 2 also include portions having locally low strength, and have a problem of reducing the overall strength.

In addition, in the case shown in patent document 3, although the control based on the impact energy is performed, there is a problem that, with respect to the sintered ore which is a brittle material, even if a small impact energy is applied, the crushing does not progress, and it is difficult to obtain an improvement in the strength of the sintered ore.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for producing a sintered ore, in which a portion having a locally low strength is removed to improve the strength of the whole sintered ore.

Means for solving the problems

In order to achieve the above object, a method for producing sintered ore according to an aspect of the present invention is characterized in that an impact force is applied to sintered ore after primary crushing, and then the sintered ore to which the impact force is applied is sorted.

Effects of the invention

According to the method for producing sintered ore of the present invention, it is possible to provide a method for producing sintered ore in which an impact force is applied to sintered ore after primary crushing, and then the sintered ore to which the impact force is applied is screened, thereby removing a portion having a locally low strength and improving the strength of the whole sintered ore.

Drawings

Fig. 1 is a diagram schematically showing a sintered ore, (a) is a schematic diagram showing a state where a crack is generated in the sintered ore, and (B) is a schematic diagram showing a state where a weak portion is formed in the sintered ore.

Fig. 2 is a diagram showing a flow of a method for producing sintered ore according to an embodiment of the present invention.

Fig. 3 is a graph showing a relationship between an impact force applied to a sintered ore and a drop height in the dropping method.

Fig. 4 is a graph showing the relationship between the weight percentage of each particle size in the drop test of example 1 and the number of drop tests.

Fig. 5 is a graph showing the relationship between the weight percentage of each particle size in the drop test of example 2 and the number of drop tests.

Fig. 6 is a graph showing the relationship between the drop strength index rise value and the number of drop tests in the drop tests of examples 1 and 2.

Fig. 7 is a graph showing the drop strength index when the rotation process by the drum method is not performed and the drop strength index when the rotation process is performed.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings. The drawings are schematic, and it should be noted that the dimensional relationship, the ratio, and the like of each element may be different from those in reality. The drawings may include portions having different dimensional relationships or ratios from each other.

First, the inventors considered that the sintered ore had a structure in which both a low-strength portion and a high-strength portion were mixed, not a uniform structure. For example, as shown in fig. 1(a), a plurality of cracks 2 or defects which become starting points of fracture exist in the sintered ore 1. Further, as shown in fig. 1(B), not only the cracks 2 but also the cracks are difficult to be uniformly sintered during the firing process, and a plurality of weak portions 3 are inevitably formed at the points of the structure and structure. Therefore, the present inventors have conceived that the strength of the sintered ore as a whole is increased by removing the portion of the crack 2, the weak portion 3, and the like, which is formed during the manufacturing process and becomes a factor of strength reduction, before the sintered ore is completed, and increasing the ratio of the high-strength portion.

As a method of this type, the present inventors have found that in order to remove a low-strength portion, a low-strength portion is broken by an external force, and the portion is separated from a high-strength portion.

Therefore, the method of manufacturing sintered ore according to the present embodiment applies an impact force to the sintered ore 1 after primary crushing, and then screens the sintered ore 1 to which the impact force is applied. By screening the sintered ore 1 to which the impact force is applied, the portion such as the crack 2 or the weak portion 3 having a low strength can be removed, the ratio of the portion having a high strength can be increased, and the strength of the sintered ore as a whole can be increased.

Further, since the sintered ore to which the impact is applied is the sintered ore after the primary crushing, the sintered ore in which the portion of the sintered ore that becomes the brittle material is removed by the primary crushing progresses the crushing even if the impact energy is applied small, and the strength of the sintered ore can be easily improved.

In describing the method for producing sintered ore according to the present embodiment, as shown in fig. 2, first, sintered ore 1 is produced in step S101. In the production of the sintered ore 1, the sintered ore 1 is produced by a general method from a CaO-containing raw material such as iron ore powder, limestone, or dolomite, a granulation aid such as quick lime, and a raw material such as coke powder or smokeless carbon, using a downward suction type dehetter-laeger (DL) sintering machine.

Next, the process proceeds to step S102, where the manufactured sintered ore 1 is crushed once. This makes it possible to obtain a sintered ore in which a portion of the sintered ore of a brittle material is removed by primary crushing.

Next, the sintered ore 1 subjected to the primary crushing in step S102 is subjected to an impact force in step S103.

The impact force is applied to the sintered ore 1 by a dropping method or a tumbling method. The dropping method is a method of dropping the sintered ore 1 from a predetermined height and breaking the sintered ore by acceleration due to gravity and impact with a floor, and is considered to be an effective method for the sintered ore 1 containing iron having a relatively high specific gravity. Here, the floor may be made of any material that can withstand impact, but a highly rigid material such as metal or ceramic may be observed to stabilize the impact force applied to the sintered ore 1 and to be damaged more stably than a material having elasticity such as a conveyor belt of a conveyor. In addition, as a material of the floor panel, since the hard resin can be reduced in weight although it has lower rigidity than metal or ceramics, it is suitable for a case where the foothold of the replacement work is narrow. Further, since the sintered ore 1 may be dropped onto the sintered ore by filling the sintered ore in a box-shaped container, the floor replacement is not necessary, and therefore, the replacement work is difficult. The drum method is a method of putting the sintered ore 1 into a rotating drum and performing a rotation process, and since an external force is applied to a portion such as the crack 2 or the weak portion 3 having a low strength a plurality of times, it is effective to break the portion.

Here, if an impact force is applied to the sintered ore 1, a high-strength portion of the sintered ore 1 may be broken depending on the magnitude of the impact force. Therefore, the magnitude of the impact force on the sintered ore 1 with respect to the falling height in the falling method was studied.

The impact force p (kgf) is calculated from the following equation (1) based on the conventional model and the use of the aggregate and the steel material.

[ mathematical formula 1]

Here, K is represented by the following formula (2).

[ mathematical formula 2]

In addition, V₀: the relative velocity (m/s) at the time of collision is represented by the following expression (3).

[ mathematical formula 3]

Where M is the mass (kg) of the sintered ore, r is the radius (M) of the sintered ore, v_SPoisson's ratio (-) v for sinter_WIs the Poisson's ratio (-), E of the floor_SYoung's modulus (Pa), E for sintered ore_WYoung's modulus (Pa) of the floor, h drop height (m), and g acceleration of gravity (Pa). Assuming that 0.3 is used as the Poisson's ratio v of the sinter_SYoung's modulus E of sintered ore of 1GPa_SWhen the high-strength steel material is used as the floor, the physical property value of the common steel and the Poisson ratio v of the floor are used_W0.3, Young's modulus E of the floor_WIs 210 GPa. Furthermore, the sintered ore has a radius r of usually 2cm and a density of 3g/cm³Treated as balls.

As a result, as shown in fig. 3, it can be confirmed that the higher the drop height is, the higher the impact force on the sintered ore 1 is. As a blast furnace raw material, it is considered that the strength impact resistance of the sintered ore 1 needs to be 100 kgf. Therefore, the impact force applied to the sintered ore 1 must be suppressed to 100kgf or less. This is because, when an impact force larger than 100kgf is applied to the sintered ore 1, a high-strength portion having sufficient strength may be broken. Referring to fig. 3, it is understood that the falling height needs to be 2m or less in order to suppress the impact force applied to the sintered ore 1 to 100kgf or less. Therefore, the falling height of the sintered ore 1 by the falling method is set to 2.0m or less.

On the other hand, when considering the lower limit of the falling height of the sintered ore 1, the present inventors focused on calcium silicate as a structure having a weak strength in the sintered ore 1. It is known that calcium silicate is weak in the structure of the sintered ore 1, and the following documents report that the tensile strength of calcium silicate is 19 MPa.

"Mineral Engineering", ASAKURA PUBLISHING CO., LTD, 1976, p.175

The calcium silicate has a tensile strength of 19MPa and a finished sintered ore 1 of +5mm in size, and therefore, when the force required to break a calcium silicate having a diameter of 5mm (assuming a circular shape) is calculated, it becomes 19MPa x (0.0025)²×π＝38kgf。

Referring to fig. 3, the 38kgf was 0.45m in terms of the falling height of the sintered ore 1. Therefore, the sintered ore 1 requires a drop height of 0.45m or more for breaking the weak portions such as the cracks 2 and the weak portions 3, and a drop height of 0.5m or more for safety reasons.

Therefore, in the present embodiment, the falling height of the sintered ore 1 by the falling method is set to 0.5m or more and 2.0m or less.

In the dropping method, the number of times of dropping is not limited to 1 time, and may be plural times in order to apply the impact force to the sintered ore 1. If the number of drops is set to a plurality of times, the locally weak portions such as the crack 2 and the fragile portion 3 can be broken more than the 1-time drops.

When the impact force is applied to the sintered ore 1 by the drum method, although not shown, the inner diameter of the drum into which the sintered ore 1 is placed is set to be 1m to 4 m. If the inner diameter of the drum is 1m or more, the sintered ore 1 has an angle of repose of 45 ° or more, and therefore, it is considered that the sintered ore 1 falls from a height of 0.5m or more during rotation. Therefore, by setting the inner diameter of the drum into which the sintered ore 1 is placed to be 1m or more, the impact force applied to the sintered ore 1 becomes 38kgf or more, and thus, the locally weak portions such as the cracks 2 and the weak portions 3 can be broken. On the other hand, if the inner diameter of the drum is made larger than 4m, the falling height of the sintered ore 1 becomes larger than 2m, and therefore the impact force applied to the sintered ore 1 cannot be suppressed to 100kgf or less. Therefore, the inner diameter of the drum into which the sintered ore 1 is charged is set to 1m to 4 m.

Next, after an impact force is applied to the sintered ore 1 after the primary crushing in step S103, the sintered ore 1 to which the impact force is applied is screened in step S104.

Here, when the impact force is applied to the sintered ore 1 by the dropping method, the sintered ore 1 is screened after the dropping of the sintered ore 1 when the number of the dropping is 1. This removes locally weak portions such as the cracks 2 and the weak portions 3, which are broken by the impact force, from the sintered ore 1, and thus the sintered ore 1 having an improved strength as a whole can be manufactured.

In the case where the impact force is applied to the sintered ore 1 by the dropping method, when the number of dropping times is plural, the sintered ore 1 may be screened between dropping and dropping, the sintered ore 1 may be screened after the last dropping, or the sintered ore 1 may be screened after dropping plural times. In this way, when the sintered ore 1 is dropped plural times, if the sintered ore 1 is sorted between the dropping and the dropping, and the sintered ore 1 is sorted after the final dropping, or the sintered ore 1 is sorted after the dropping plural times, a locally weak portion such as the crack 2 or the weak portion 3 which is more broken than the dropping by 1 time can be removed from the sintered ore 1, and the sintered ore 1 having further improved strength as a whole can be manufactured.

In addition, in the case where the impact force is applied to the sintered ore 1 by the drum method, the sintered ore 1 is screened after the impact force is applied. This also removes locally weak portions such as cracks 2 and weak portions 3 that are broken by the impact force from the sintered ore 1, and thus the sintered ore 1 having an improved strength as a whole can be produced.

When the sintered ore 1 is screened through step S104, the production of the sintered ore 1 is ended.

While the embodiments of the present invention have been described above, the present invention is not limited to the embodiments, and various changes and improvements can be made.

For example, the impact force may be applied to the sintered ore 1 by a method other than the dropping method or the tumbling method, for example, by a vibration method.

The impact force can be changed depending on the strength required for the blast furnace raw material, and the falling height of the sintered ore 1 in the falling method is not limited to 0.5m or more and 2.0m or less.

Similarly, the inner diameter of the drum in the drum method is not limited to 1m or more and 4m or less.

Alternatively, the sintered ore after the primary crushing may be classified before the impact force is applied to the sintered ore, the impact force may be applied only to the sintered ore under the screen, the sintered ore under the screen to which the impact force is applied may be mixed with the sintered ore on the screen, and then the mixed sintered ore may be screened. The number of times of applying the impact force to the sintered ore after the primary crushing may be 1 or more, and in the case of 1 time, the sintered ore is classified before the impact force is applied for 1 time, the impact force is applied only to the sintered ore under the sieve, and the sintered ore under the sieve to which the impact force is applied and the sintered ore on the sieve are mixed. In addition, in the case where the sintered ore is subjected to impact force a plurality of times, the sintered ore is classified before the impact force is applied at least 1 time, only the undersize sintered ore is subjected to the impact force, and the undersize sintered ore to which the impact force is applied is mixed with the oversize sintered ore.