JP2000246177A - Raw material sieving method and sieving apparatus - Google Patents

Abstract

(57) [Summary] [PROBLEMS] When sieving raw materials using a plurality of sieves having an inclined sieve surface, the size of the target particle size can be reduced while downsizing the sieving apparatus to reduce the equipment cost burden. Provided are a raw material sieving method capable of efficiently sieving a raw material, and a sieving apparatus for performing the method. SOLUTION: A plurality of stages are arranged from top to bottom in the order of the size of the sieves, and the raw materials are sieved while sequentially flowing down the sieves of the respective stages from the uppermost sieve. Further, in the sieving method of the raw material to be sieved, when sieving while flowing the sieved raw material of the former sieve in each of the second and subsequent stages, after the supply part of the raw material from the former stage (downstream side), A raw material sieving method, characterized in that the raw material on the former stage is supplied again and sieved together with the raw material on the lower stage from the former stage,
A sieving device for performing this method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sieve for a raw material used for adjusting the particle size of iron ore raw materials such as iron ore, sinter ore, limestone and coke to be charged into a blast furnace within a predetermined particle size range. The present invention relates to a separation method and a sieving apparatus.

[0002]

2. Description of the Related Art Conventionally, for example, in order to stably maintain the operation efficiency of a blast furnace, it is necessary to adjust iron ore, sinter, limestone, coke, and other iron-making raw materials to a predetermined particle size range.
For this purpose, a sieving apparatus is used. In order to respond to the demand for downsizing, for example, as shown in FIG. 3, this sieving apparatus has two upper and lower sieves, an upper sieve 21 having a large sieve and a lower sieve 22 having a small sieve disposed below the upper sieve 21. Are used to reduce the installation area on the plane of the sieve and reduce the amount of handling of the lower sieve that determines the lower limit particle size.

The upper and lower sieves 21 and 22 used here are:
It has inclined screen surfaces 23 and 24, and the supplied raw material 25 is sieved while flowing down the inclined screen surfaces 23 and 24. Here, the raw material 25 is supplied to the uppermost part of the upper sieve 21 from the supply supply device 26, and is sieved while flowing down the inclined sieve surface 23, and the raw material 27 of the upper sieve 21 rolls on the inclined sieve surface 23. Then, it is supplied to the transfer device 28 and transferred to the blast furnace (not shown).

On the other hand, the raw material 29 under the upper sieve 21 is supplied to the uppermost part of the lower sieve 22 through the chute 30 and is sieved while flowing down the inclined sieve surface 24 of the lower sieve 22.
The on-screen raw material 27 of the lower sieve 22 is supplied to the conveying device 28 by rolling on the inclined sieve surface 24, and is supplied to the conveying device 28, similarly to the above-screen raw material 29 of the upper sieve 21, and the blast furnace (not shown) ).

On the other hand, the raw material 29 below the lower sieve 22 is temporarily stored in a storage hopper 32 via a chute 31. The under-sieving raw material 29 of the lower sieve 22 has a particle size smaller than the lower limit of the predetermined particle size range, and when charged into a blast furnace, causes clogging in the furnace, which is preferable. Timely, because the operation efficiency is reduced due to the inability to obtain a
It is sent from the storage hopper 32 to a processing plant such as a sintering plant or a pellet plant.

[0006] In the conventional sieving apparatus configured as described above, those having a particle size equal to or smaller than the lower limit of the predetermined particle size range adhere and mix in the raw material 27 on the upper screen 2 to reduce the sieving efficiency. In addition to this, there is a disadvantage that the raw material is transferred to the blast furnace as a raw material of the blast furnace. Therefore, it is necessary to take measures such as increasing the size of the blast furnace or increasing the number of stages.

Further, in the case of a sieving apparatus, the cost of equipment increases with an order higher than the first-order proportion because of an increase in the area of the sieving surface and a design reason for securing the strength of the sieving frame member and the vibrating apparatus. In particular, large-scale processing in the steel and mining industries is required,
When using a large sieving apparatus, the tendency is remarkable. In addition, in a plant that has already been installed, when it is necessary to increase the capacity of an existing sieving apparatus for reasons such as capacity increase, it is often difficult to significantly change the layout due to site restrictions. Therefore, there is also a problem that it is difficult to newly install a large sieve adapted to the required capacity.

As shown in FIG. 4, the inclined sieve surface is divided into a larger sieve surface 33 and a smaller sieve surface 34.
It is also conceivable to improve the sieving efficiency while reducing the size of the sieving apparatus using sieves 35 arranged in three or more stages. That is, the raw material 25 from the supply device is sieved on the primary inclined sieve surface 33, the raw material on the sieve 27 is supplied to the conveying device, and the raw material 29 below the sieve is sieved on the secondary inclined sieve surface 34,
It is also conceivable to supply the on-sieve raw material 36 to the transport device and temporarily store the under-sieve raw material 37 in the storage hopper 32 via the chute 30.

However, in general, it is necessary to frequently replace the sieve mesh forming the sieve surface. When a plurality of inclined sieve surfaces 33 and 34 as shown in FIG. It takes time to replace the sieve mesh that forms the inclined sieve surface 34, and the time required for periodic repairs increases. In the process of continuous operation such as sintering furnace and blast furnace, if there is no spare machine, it is necessary to install a spare machine because the whole factory needs to be stopped, which is uneconomical. There's a problem.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a raw material sieving apparatus using a multistage sieve having an inclined sieve surface.
A raw material sieving method capable of efficiently sieving a raw material having a desired particle size while reducing the equipment cost burden by downsizing the sieving apparatus, and advantageously solving the problems with the conventional sieving apparatus, An object of the present invention is to provide a sieving apparatus for performing the method.

[0011]

Means for Solving the Problems The first invention of the present invention is:
Sieves having different sizes of sieves having inclined sieve surfaces are arranged in a plurality of stages from top to bottom in the order of the size of the sieves, and the raw materials are sieved while sequentially flowing down the sieves of the respective stages from the uppermost sieve. In the raw material sieving method in which the raw material under the sieve is further sieved by the next sieve, when the raw material under the sieve of the previous sieve is flowed down in each of the second and subsequent stages, the sieve from the former stage is used. A raw material sieving method characterized in that a raw material on a previous stage is supplied to a downstream side from a supply position of a lower raw material, and the raw material is sieved together with a raw material below the raw material from the previous stage.

According to a second aspect of the present invention, there is provided a sieve apparatus in which sieves having different sizes of sieves each having an inclined sieve surface are arranged in a plurality of stages from the top to the bottom in the descending order of the size of the sieves. A raw material characterized in that a supply unit for the pre-staged raw material is provided at the top of the raw material, and a supply unit for the pre-stage raw material is provided downstream of the supply position of the raw material for the previous stage in each stage. , Which is positioned as an example of the sieving apparatus for implementing the first invention.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a percolation phenomenon (for example, a mixed raw material of fine particles and agglomerated particles is rolled on a slope) in the raw material on the sieve which has been sieved by the former (upper) sieve. In the case where the fine particles are moved, fine particles that cannot reach the sieving surface and are not sieved are mixed due to the phenomenon that the agglomerates are separated upward and the fine particles are separated downward. To the lower end of the upper sieve, and the raw material on the sieve is fed onto the raw material under the previous sieve being sieved with the next (lower) sieve, The fine particles that have not been sieved with the sieve described above are reliably sieved with the lower sieve to improve the sieving accuracy (efficiency).

The feed position of the raw material on the upper screen to the raw material on the lower screen of the upper sieve being sifted by the lower sieve is downstream of the raw material for supplying the raw material of the upper screen. Thereby, sufficient sieving efficiency can be secured. For example, it is conceivable to set the supply position of the raw material on the upper sieve to the same position as the raw material supply position of the lower sieve in the upper sieve. Since the sieving is performed on the entire sieving surface of the lower sieving screen, the sieving ability is greatly reduced. In addition, here, a large amount of fine particles finally sieved in the lower stage is mixed, and the drop efficiency of the fine particles mixed in the raw material under the sieve and the raw material on the sieve supplied mixed thereto is reduced. There is a problem that the sieving efficiency is greatly reduced due to a large decrease.

The raw material supplied to the lower sieve is sieved in the upper and lower sieves so that fine particles having a size smaller than the mesh size of the lower sieve are not mixed as much as possible. ,area,
It is also necessary to select the sieve opening conditions and to select the feed position of the raw material on the upper sieve to the lower sieve.

The sieving efficiency is determined from the probability that the fine particles to be excluded by sieving come into contact with the sieve mesh (sieve surface) and the probability that the fine particles fall from the sieve mesh.
Basically, the sieving efficiency is improved by increasing the contact probability of the former. Further, in the present invention, it is possible to secondarily prevent the adhesion of fine powder particles and the sticking of small-diameter particles into the sieve mesh by the impact of the raw material on the sieve from the previous sieve, and the clogging of the sieve mesh of the sieve mesh. To prevent a decrease in sieving efficiency.

The present invention is applied to a sieve in which sieves having inclined sieve surfaces having different sieve sizes are arranged in multiple stages from top to bottom in the order of larger sieves. A sufficient effect can be obtained by arranging two stages. When the sieves are arranged in three stages, the application of the present invention between the stages is not meaningless, but does not significantly increase the effect.

The method for sieving raw materials and an example of a sieving apparatus according to the present invention will be described below. Here, an example of an iron ore sieving apparatus to be charged into a blast furnace will be described with reference to FIGS. In this example, the sieve is arranged in two stages, upper and lower. In FIG. 1, reference numeral 1 denotes a raw material sieving apparatus of the present invention, which is an upper sieve 2 having an inclined sieve surface 2c, and an inclined sieve surface 3 below which an upstream side partially overlaps with the upper sieve 2 when viewed planarly.
The lower sieve 3 having a c is provided, and a chute 4 is disposed below the upper sieve 2. Outlet 4a of this chute 4
Is located above the uppermost stream of the lower sieve 3, and feeds the raw material 12 from the upper sieve 2 to the uppermost part of the lower sieve 3 via the chute 4.

A chute 6 is provided below the lowermost end of the inclined sieve surface 2c of the upper sieve 2. The lower end of the chute 6 is located above the middle part of the inclined screen 3 c of the lower screen 3, and the raw material 13 from the upper screen 2 passes through the chute 6 to the middle of the inclined screen 3 c of the lower screen 3. Supply. A chute 7 is provided below the lower sieve 3. This chute 7 is used for the raw material 14
Is supplied to a storage hopper 8 provided separately from the sieving apparatus 1.

A chute 9 and a belt conveyor 10 are disposed below the lower end of the inclined sieve surface 3c of the lower sieve 3. This belt conveyor receives the on-screen raw material 15 of the lower sieve 3 and converts it into, for example, a blast furnace (not shown).
To be transported to Reference numeral 11 denotes a raw material supply device disposed close to the uppermost part of the upper sieve 2, the supply end of which is located above the uppermost stream part of the upper sieve 2, and feeds the raw material 5 to be sieved to the uppermost part of the upper sieve 2. It is supplied to the upstream part.

The sieving operation of the raw material by the sieving apparatus 1 will be described with reference to FIG. The raw material 5 is supplied from the raw material supply device 11 to the uppermost part of the upper sieve 2 and the inclined sieve surface 2
The sieve material 12 having passed through the sieve surface 2 c is supplied to the uppermost stream of the lower sieve 3 via the chute 4. The upper raw material 13 of the upper sieve 2 is supplied to the intermediate portion of the inclined sieve surface 3c of the lower sieve 3 by rolling the inclined sieve surface 2c of the upper sieve 2. At this time, on the inclined sieve surface 3c of the lower sieve 3, the raw material 12 from the upper sieve 2 is flowing down.
The raw material 13 from the upper sieve 2 supplied to the intermediate portion of the inclined sieve surface 3c is supplied thereon, and merged therewith and sieved.

When the raw material 13 from the upper screen 2 is supplied to the lower screen 3, the raw material 13 in the upper screen 2 contains
The mixing of the particle size less than the mesh size of the lower sieve 3 is small,
In addition, since the raw material having a particle size equal to or smaller than the mesh size of the lower sieve 3 is in the lower layer, the probability of contact between the particles and the sieve net to be sieved is not reduced. Therefore, the sieving efficiency does not decrease.

When the raw material 13 from the upper screen 2 is supplied to the lower screen 3, the raw material 1 is supplied to the lower screen 3.
Since the drop impact of No. 3 is applied, the separation and falling of the fine particles attached to the raw materials 13 and 12 and the sieve net are promoted, and the sieving efficiency is improved. Raw material on screen 13, 1, sieved through lower screen 3
5 is supplied to a belt conveyor 10 via a chute 9 and conveyed to a blast furnace. On the other hand, the raw material 14 sieved through the lower sieve 3 is supplied to the storage hopper 8 via the chute 7.

[0024]

EXAMPLE Using the raw material sieving apparatus of the present invention as shown in FIG. 1, the ore charged in the blast furnace was sieved to evaluate the effect of the present invention. Hereinafter, the execution conditions, the execution results, and the evaluation results are shown in comparison with the case of the comparative example. The comparative example here is the case of the conventional example in which the sinter on the upper sieve is not supplied to the lower sieve. In addition,
In this example, sintered ores having a particle size of 20 mm or more to be charged into a blast furnace were sieved from sintered ores having a particle size distribution as shown in Table 1.

As shown in Table 2, the evaluation was as follows: (1) Recovery rate of sintered ore of 20 mm or less recovered under the lower sieve (wt%) (2) Sinter ore on the lower sieve The test was carried out at a mixing ratio (wt%) of fine powder having a particle size of 5 mm or less.

(Sieving conditions) Target raw material: sinter ore Supply amount: 1200 t / h Particle size distribution: as shown in Table 1 Sieve Upper sieve Model: Fixed grizzly Area: 15 m ² (width 3 m × length 9 m) Incline angle : 36 degree sieve mesh opening: 40 mm lower sieve Model: linear vibration type vibrating sieve Area: 27 m ² (width 3 m x length 9 m) Inclination angle: 17 degree sieve mesh opening: 20 mm upper sieve to lower sieve Supply position of sinter on the sieve: approximately in the middle of the inclined sieve surface

[0027]

[Table 1]

[0028]

[Table 2]

As shown in Table 2, in the embodiment of the present invention,
(1) A recovery rate (wt%) of the sintered ore of 20 mm or less collected under the lower sieve was 85%. That is, it was greatly improved with respect to the comparative example which was 60%. (2) The ratio (wt%) of fine particles having a particle size of 5 mm or less mixed in the sintered ore on the sieve in the lower sieve is 2%, that is, the particle size charged to the blast furnace is more than 20 mm. 2% of fine particles adhering and mixing in the sintered ore of No. 1 was significantly improved as compared with Comparative Example having as much as 12%.

As described above, by practicing the present invention, the sieving efficiency can be greatly improved, and the sintered ore having a predetermined particle size range in which the adhesion of fine powder particles is extremely small is reduced to the lower sieve. Was efficiently sieved as a raw material.

The present invention is not limited to the above example. For example, in the above example, the sinter to be charged into the blast furnace was subjected to sieving.However, iron ore, limestone, other ironmaking raw materials such as coke, and general lump in other fields,
It can be applied to raw materials such as a mixture of granules and powders, and the flow distance, inclination angle, size of sieves, number and arrangement of sieves, the former stage The conditions such as the sieve structure such as the supply position of the raw material on the sieve, the structure, size, arrangement, etc. of various chutes and other components are sieved, processing amount, particle size distribution, predetermined particle size range on the sieve, sieve There are some changes depending on the sorting conditions and the like.

[0032]

According to the present invention, in a raw material sieving apparatus using a multi-stage sieve having an inclined sieve surface, the raw material on the former sieve in which fine grains are mixed is sieved by the next sieve. By feeding on the raw material under the sieve of the previous sieve and sieving together with the raw material under the sieve of the former sieve, the falling of fine particles mixed in the raw material on the sieve at the former sieve is promoted, and the sieving accuracy (Efficiency) can be improved. It is also possible to reduce the equipment cost burden by realizing a compact sieving device.

[Brief description of the drawings]

FIG. 1 is an explanatory side view illustrating a structural example of a sieving apparatus of the present invention.

FIG. 2 is an explanatory side view schematically showing a flow of raw materials to be sieved by the sieving apparatus of the present invention.

FIG. 3 is an explanatory side view schematically showing a structural example of a conventional sieving apparatus.

FIG. 4 is a side view schematically showing a structural example of a sieving apparatus for improving sieving efficiency.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 sieving device 2 upper sieve 2c inclined sieve surface 3 lower sieve 3c inclined sieve surface 4 chute 4a outlet 5 raw material 6 chute (for raw material above upper sieve) 7 chute (for raw material below lower sieve) 8 storage hopper 9 Chute (for raw material on the lower sieve) 10 Conveyor 11 Material supply device 13,15 Raw material on the sieve 12,14 Raw material on the sieve

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tsuyoshi Urabe 1 Kimitsu, Kimitsu-shi, Chiba Nippon Steel Corporation Kimitsu Works (72) Inventor Takashi Aramaki 1-3-3 Nakaharashinmachi, Tobata-ku, Kitakyushu, Fukuoka Prefecture No. In Adachi Co., Ltd. (72) Inventor Masashi Nakayama 3-1-1 Higashikawasaki-cho, Chuo-ku, Kobe-shi, Hyogo F-term in Kawasaki Heavy Industries, Ltd. Kobe Factory 4D021 AA03 AB03 CA01 CA07 DA01 DA13 DA15 DA20 DB20 EA05 EA10 4K001 AA10 BA04 CA02

Claims (2)

[Claims] 1. A plurality of sieves having different sizes of sieves having an inclined sieve surface are arranged in a plurality of stages from top to bottom in the order of the size of the sieves. In the method of sieving the raw material, in which the raw material under the previous sieve is further sieved with the sieve of the next stage, when sieving the raw material under the sieve of the former stage in each of the second and subsequent stages, A method for sieving a raw material, comprising supplying a raw material on a previous stage to a downstream side of a supply position of a raw material from a former stage and sieving the raw material on the former stage. 2. In a sieving apparatus in which sieves having different sizes of sieves each having an inclined sieve surface are arranged in a plurality of stages from the top to the bottom in the descending order of the sieves, the uppermost part of each of the second and subsequent stages from the top. A raw material sieving characterized in that a feed unit for the raw material of the former stage is provided at a downstream side from a supply position of the raw material for the former stage in each stage, and a supply unit of the raw material for the former stage is provided in each stage. apparatus.