JPS5842733A - Manufacture of sintered ore - Google Patents

Abstract

PURPOSE:To obtain sintered ore with superior cold strength and a high FeO content at a low coke unit in a high yield without increasing the negative pressure of the blower of a sintering machine by using a starting material with a specified high gas permeability or above and regulating the thickness of a layer of the material on the sintering pallet to a specified value or above. CONSTITUTION:Coke breeze 10 as a heat source is added to a starting material 9 composed of iron ore 1, limestone 2, miscellaneous starting materials 6 such as mill scale 3, converter slag 4 and electric furnace slag 5, and return ore 7, and the blended starting material 11 is mixed by means of a drum mixer 12. The mixture is fed to a disk pelletizer 27 to prepare a starting material 14 with >=70 JPU gas permeability, and a layer 21 of the material 14 on the pallet 16 of a sintering machine 15 is sintered while regulating the thickness of the layer 21 to >=700mm. fixed value.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing sintered ore, and in particular to a method for producing sintered ore, which has two excellent qualities such as sintered ore strength and reduced Fe○ in the finished sintered ore, and has a low coke consumption rate. The present invention relates to a method for producing sintered ore that can be obtained at a high yield.

As is well known, sintered ore is produced by mixing raw materials such as iron ore, 9 limestone, and coke powder as a heat source in a drum mixer, adding moisture and granulating the raw material, and charging the raw material onto the DL2 sintering machine pallet. It is produced by forming a raw material layer, igniting it in an ignition furnace, and firing it while drawing air downward while gradually guiding the combustion of coke breeze from the upper layer to the lower layer. The raw material mixing and granulation step in the sinter production process is as shown in FIG. 1: iron ore 12 limestone 2. Mill scale 3. Converter slag4.
Miscellaneous auxiliary raw materials such as electric furnace slag5 etc.6. Mixed raw material 11 made by adding coke powder 10 as a heat source to return ore 7 (quicklime °C as a binder may also be blended) and other raw materials 9 - 1st and 8th drum mixers 12 and 13 The raw materials 14 charged to the sintering machine are obtained by mixing and granulating the raw materials 14.

The raw material 14 is supplied to the pallets 16 of the DL sintering machine 15 by dropping the raw material 14 from the hopper 18 of the raw material supply device 17 via a drum feeder, an feeder 19, or a belt feeder (not shown) into a sloping pump. ``shi''-to 2
The raw U layer 21 of a predetermined thickness is continuously formed on the pallet 16 of the sintering machine through the sintering machine pallet 16.

The raw material layer 21 includes 22 groups of wind boxes provided under the pallet 16, 23 groups of exhaust branch pipes, and an exhaust gas exhaust duct 2.
4. Blower! While air is sucked in the direction of 25A, ignition is performed in the ignition furnace 26 downstream of the raw material supply device 1-1, and the coke breeze in the raw material layer 21 is gradually guided from the upper layer to the lower layer and sintered. be done.

The goals of the sinter operation described above are three points: 0 quality (satisfying strength and composition standards, ■ increasing productivity, and ■ lowering the coke consumption rate. The current levels of the above target values are as follows.

That is, the negative pressure of the blower 725 of the sintering machine 15 is 1000~
At about 1600 to Aq, the layer thickness of raw material 6 square 2] is 300-5
00frIjn, production rate is 1.4~1.5T/h
r/m2 (approximately 33,6-3e, oTB-D), and the quality of the sintered ore is FI30 (finished product F).
ed) has a food content of 6 to 11%.

For example, raw material 9 with the blending ratio shown in Table 1 and raw material 11 with the particle size distribution shown in Table 3 to which 3.2% of powder cox 10 with the particle size shown in Table 2 was added are mixed and manufactured using drum mixers 12 and 13. The average particle size of the granulated raw material 14 is 2.5 to 3.5 m.
m, '1.0 mm 20 to 30%, and the index showing the air permeability of this raw material 14 was 40"JIU to 50 JPU. This raw material 14 with an air permeability of 50.TPU was subjected to -DL sintering with the specifications shown in Table 4. A raw material layer 21 with a layer thickness of 500 m is formed by charging the raw material supply device 17 into the machine 15, and the production rate is 35 T/
Sintered at +m'・D.

As a result of this operation, the finished product walk @ '7.5%, the cold strength (S
X)/'T -S and it was over. Table 5 also shows the sintered ore components.

(1971), is the six-point strength index of sintered ore.

Note (2) The air permeability P (,, TPU), which indicates the air permeability of the raw material 14, is 1. The material is placed in a glass container shown in Figure 2 and sucks air at 75λ/wR. However, if the suction pressure of this sowing is Sr++mAq, then the air permeability P is calculated using the following formula.

, v: ventilation volume (-/body) = near 5XIO 赫i ・A: I & drawing area (rn') = a, 4zx1o
rr? h: Charging layer thickness (m) ==0.3'm B: Suction pressure (wnAq) Table 1 Mixing ratio of raw materials.

, ・Table 2 Raw material coke powder Table 3 Particle size distribution table of raw materials Table 4 Sintering machine Table 5 Sintered ore components Cold strength, finished product FeO
This product provides a manufacturing method that can produce sintered ore with low coke consumption and high yield, and its technical philosophy is to sinter highly permeable raw materials in a high thickness layer. .

The method for producing sintered ore of the present invention will be explained below.

The present inventors charged the raw material 14 with an air permeability of 50 JPU after the drum mixer 13 in FIG. to 5
The sintered ore was divided and the Feo and cold strength of the sintered ore at each layer height were investigated. The results are shown in FIGS. 3 and 4. From this, it is clear that FeO decreases as the layer becomes lower in the layer thickness direction, while the strength increases as the layer becomes lower, and becomes almost constant from about 400 to the upper layer.

Based on these investigation results, the present inventors were able to reduce FeO and increase the cold strength of the finished product by increasing the lower layer with relatively low FeO and high cold strength in the layer thickness direction. I focused on the points.

Therefore, the raw material 14 was placed in a test pot with a layer thickness of 600,700 mm, which is larger than the current layer thickness of 500 mm. The sintered ore was charged so as to have an angle of 50°800, was fired, and after firing, the FeO and cold strength of the sintered ore at each position in the layer thickness direction were investigated.

Among these survey results, the results for the '75 ot+m layer thickness are also shown in Figures 3 and 4. From this test result, with the current layer thickness of 500rran, the average FeO in the layer thickness direction was 5.56%, and the average cold strength in the layer thickness direction was 76.1%, but 600,70ρ,'i' 50°800y
It was found that at a high layer thickness of nm, the ratio of low FeO part and cylindrical strength part increases, and the average product FeO in the layer thickness direction and the average cold strength in the layer thickness direction change in the direction j as shown in Table 6.

Table 6 From the above investigation results, in the present invention, sintering is performed at a layer thickness of 700 rrrm or more, which has a sufficient margin for improvement in both F, eO, and cold strength compared to a layer thickness of 5C+Omm.

Next, the influence of the blending ratio of coke 1O in the raw material 9 in the sintered ore manufacturing flow shown in FIG. 1 on the product strength and product FeO was investigated.

Specifically, in the flow of diagram g1, the blending ratio of coke 10 to the raw material 9 is 3, O, , 3, 2, 3, 4° 3
, the coke blending ratio obtained by adjusting it to 6% 3. O, '3.
A pot test similar to that described above was carried out using the raw material 14 of 2°3.4% and 3.6% for two types of layer thickness: 500 m and 750 m. The results are shown in FIG. From Figure 5, the coke blending ratio necessary to ensure product strength (S work) of 88% is 11 layers from 500+mm to 7501MI.
By increasing the thickness of the upper layer, it decreased by 0.28%, and the product F
It was revealed that eO also decreased by 1.1%.As shown in 2, by sintering to a layer thickness of more than 'i'oom, sintered ore with improved product strength and product FθO can be produced with low coke. However, with the existing DL sintering machine where the blower negative pressure is a predetermined value, the current 5'O
When the layer thickness increases from O■ layer thickness to 700 or more, the permeability of the raw material layer on the pallet deteriorates. This will inevitably lead to a drop in production rate.

For example, FIG. 6 shows the relationship between the layer thickness and productivity of the raw material with air permeability P=50 JPH in the sintering machine shown in Table 4 with a blower negative pressure of 1500 mAq. That is, for example, layer thickness f: 500y+
If from on to 7oOwn, productivity Id is 35
T/i・D decreases to 30T/m2-D.

Furthermore, for example, if the layer thickness is 800cm, the productivity is 35T/fn2.
・If you try to maintain D, the blower negative pressure will be 250
0? +1mA C1 is required.

Therefore, the present inventors investigated a method of maintaining the productivity at the current i5oomm layer thickness without increasing the blower negative pressure of the sintering machine even when the layer thickness is increased to i'70 ot++ m or more. . As a result, the mixed granulated raw material 14 is charged onto a pallet and forms a raw material layer 21 with a predetermined thickness.
The idea was to increase the ventilation r(JPU)k'M. Then, the air permeability P (JPU) and productivity (Tk”/D) of the raw material 14 using the layer thickness as a parameter under the blower negative pressure of 1500 mAq
) was newly discovered as shown in Figure 7. That is,
At a layer thickness of 00 m, the required air permeability P of the raw material 14 is 70 J.
It is more than PU and is more than 80 JPU in soo scream.

Therefore, the inventors next determined that the air permeability P is 70 to 80 JPU.
A method for obtaining highly air permeable raw material 14 was studied.

In this study process, the inventors first investigated the particle size structure of the blended raw material 11 and the granulated raw material 14 discharged from the drum mixer 13 in the process shown in FIG. FIG. 8 shows the results of the investigation, and the broken line indicates the blended raw material 11, and the dashed line indicates the granulated raw material 14.

Although the particle size distribution of the granulation raw material 14 has decreased in the fine part, there are still 20% of -2 φ particles, and these fine particles impede the air permeability of the raw material layer, and the permeability P is reduced. 50JP
It was found that it remained at a low rank of U.

Therefore, when granulating the blended raw materials for the purpose of strengthening granulation, we changed the granulation machine to the drum mixer 13 and used a disk-type pelletizer, and as a result, the permeability P of the granulated raw materials was reduced to 80 J.
I was able to make it P and U. At this time, the disk type pelletizer used had a diameter of 6 mφ, and the operating conditions were a disk rotation speed of 9 r, p, m de, an isk angle of 54°, and a raw material supply rate of 130 T/H.

FIG. 8 also shows the particle size distribution of the raw material obtained by granulating the mixed raw material from the drum mixer 12 using the disk type pelletizer as described above.

In this way, in the disk-type pelletizer granules, the adhesion of fine particles to coarse particles is promoted, the average particle size is improved, and the particle size distribution is made uniform. As a result, the air permeability of the granulated raw material was improved, and the air permeability of the raw material was 80 JPU.

From the above study results, the current layer thickness ranges from 500 to '700.
Low coke consumption by making the layer thicker than g
Although it is possible to obtain finished product FeO and sintered ore with excellent cold strength, the current pre-treatment method for charging raw materials has a permeability P of about 50.7 PU, and the current sintering machine's processor In order to eliminate the drawback that productivity decreases unless the negative pressure is increased, the present invention uses, for example, granulating the blended raw materials with a disk-type pelletizer.
We obtained a raw material with high air permeability of U or higher, and this air permeability P is '70J.
It uses a highly air permeable raw material that is higher than PU.

In other words, a highly air permeable raw material with an air permeability of 70 JPU or more is layered with a layer thickness of 70 JPU or more.
By sintering with a high layer thickness of ooto+ or more, the current 5
A layer thickness of 500? llIn
The blower of the existing sintering machine that is sintered with the blower of the existing sintering machine produces excellent quality sintered ore with low coke consumption, low finished product FθO, and high cold strength without increasing the negative pressure or reducing productivity. can be manufactured.

Production 70-' carrying out the method for producing sintered ore of the present invention
An example is the passage in FIG. In FIG. 9, a disk-type pelletizer 27 is installed in place of the drum mixer 13 in FIG. layer 2
The layer thickness of No. 1 is set to a constant value of 700 WrTn or more.

Table 6 shows examples of the present invention method along with the conventional method. In addition, methods for obtaining highly air permeable raw materials of 70 JPU or more include not only the method using the disk type pelletizer described above, but also various methods such as adding a binder such as bentonite with excellent granulation ability and granulating it with a drum mixer. method can be adopted. However, the method using a disk type pelletizer is
It is economically superior as it allows you to obtain highly air permeable raw materials without using special binders etc.

[Brief explanation of drawings]

1117J is an explanatory diagram of a conventional method for manufacturing sintered ore, Figure 2 is an explanatory diagram of a method for measuring the permeability of raw materials, and Figures 3 and 4 are
The figure is an explanatory diagram of the investigation results of FeO and cold strength of sintered ore at each position in the layer thickness direction, and Figure 5 is the relationship between the coke blending ratio, which is the layer thickness t parameter, and the product strength and product FeO Figure 6 is an explanatory diagram of the relationship between layer thickness and productivity. Figure M is an explanatory diagram of the relationship between raw material permeability and productivity.
The figure is an explanatory diagram of the raw material grains before granulation and the raw material grains after granulation, and FIG. 9 is an explanatory diagram of the uninvented method for producing sintered ore. l○... ... Coke powder J... Blended raw material U2... Drum mixer] 3... Drum mixer 14...
Charged raw material 15...DL sintering machine 16... Pallet 17... Raw material supply device 21... Raw material layer 22... Wind box 23... ...Exhaust branch pipe 24...Exhaust gas discharge duct 25...Blower 26...Ignition furnace 27...Applicant for disc type pelletizer
Nippon Steel Corporation Figure 1 Figure 4111ffi, Figure 5

Claims (2)

[Claims] (1) When producing sintered ore with a sintering machine, the air permeability '7
A method for producing sintered ore, characterized in that the material layer on a sintering machine pallet has a layer thickness of 7 oofi or more using a highly air permeable raw material of 0 JPU or more. (2) The method for producing sintered ore according to claim (1), wherein the highly air permeable raw material having an air permeability of '70 JPU or more is obtained by granulating the blended raw materials with a disk-type pelletizer.