JPS60169527A - Production of sintered ore - Google Patents

Abstract

PURPOSE:To improve air permeability of a sintering layer and to produce sintered ore having uniform quality at a good yield by sieving a sintering raw material, granulating the pulverous powder, grinding the coarse particles, supplying only the raw material having an adequate particle size to a sintering machine and sintering said material. CONSTITUTION:A sintering raw material formed by compounding about 60% iron 1, about 10% limestone 2, about 20% sinter returns 3 and about 10% powder coke 4 is passed through a dryer 21 to about 0.5% moisture and thereafter the raw material is sieved by a 5mm. screen 22 then 1mm. screen 23. The coarse particles of >=5mm. obtd. by the sieving are passed through a grinding machine 26 and are the successively sieved by a 1mm. screen 24 and a 5mm. screen 25. The coarse particles of >=5mm. are returned again to the machine 26. The pulverous powder of <=1mm. obtd. by the sieving is pulverized by a grinding machine 27 and is then granulated to 5-1mm. by a pelletizer 28. Only the raw material of 5-1mm. particle size obtd. by the screens 22, 23, 24, 25 and the pelletizer 28 is thus uniformly mixed in a drum mixer 29 and is then supplied to a sintering pan 30, by which the material is sintered and the sintered ore is obtd.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method for producing sintered ore.

More specifically, the present invention adjusts the particle size of the sintered ore raw material, improves the permeability of the sintered raw material in the sintering machine, and produces sintered ore with uniform quality without uneven firing. Regarding how to.

Conventional technology sintering raw materials usually contain about 40% of fine particles of 1 mm or less and 1
Composed of approximately 0% coarse grains of 5 mm or more, and fine grains]11
The grain size ratio is large. For this reason, a method is used in which a coagulant for pseudo-granulation is added to granulate the fine powder raw material, and then the raw material is fed to a sintering machine. However, even with this kind of treatment, the amount of fine powder less than 1 mm still exists at around 20%, and only 5.
The amount of coarse particles larger than mm increases to about 20%, and the effect of making the particle size uniform is small.

If the particle size of the raw Fl is uneven and the particle size ratio of fine powder and coarse particles is large, the fine powder will fill the gaps between the coarse particles, resulting in poor air permeability. When stacked on a sintering machine, the filling state becomes uneven and uneven ventilation occurs in the sintered layer. The sintering reaction is difficult to proceed in areas with poor air permeability and little ventilation 17j, and the sintered ore is discharged from the sintering machine with insufficient firing, resulting in a poor yield of sintered ore and large variations in quality.

To explain in more detail, the raw materials used in sintering are the first
As shown by the solid line in the figure, coarse particles and fine particles coexist, so as a pretreatment, water is added and then granulated using a drum or the like. In the mixing granulation process in the production of sintered ore according to the prior art, as shown in Fig. 2, iron ore, which is the main raw material, is
, return ore 3 and coke powder 4 are added to auxiliary raw materials 2 such as limestone to form a blended raw material 5, and this blended raw material 5 is first mixed into 1 ton.
6, and add the required amount of water to it and mix. After further mixing, the blended raw materials 5 are passed through two wide rotary drums 1 and 7.
Add an appropriate amount of water to create a pseudo-granule.
The granules are discharged and charged into the sintering machine 8.

The particle size distribution of the discharged granules is as shown by the dashed line in Figure 1, with approximately 20% of fine particles of 1 mm or less present, and 5.
It is in a coarse powder mixed state in which approximately 20% of coarse particles with a diameter of mm or more are present. As a result, the gaps between the coarse grains are filled with fine powder, and the -C ventilation path is blocked, resulting in insufficient suction of air into the coke combustion chamber, and the progress of sintering is hindered. In addition, the abundance ratio of coarse particles and fine particles in the raw material is not constant, and the raw material filling properties differ significantly in the vertical and horizontal directions of the sintering machine. Raw material filling performance affects air permeability, and the sintering progress rate, which depends on ventilation, changes at each position in the sintering machine, resulting in some unfired parts, causing a decrease in yield. , and the variation in quality also increases.

A commonly used measure against this problem is the Special Publication No. 53828.
This is a method of accelerating granulation by adding a specific caking powder, as disclosed in No. 3 Yuki Publication. However, in the known methods 1 and 2, the phenomenon of granulation of fine powder and ]II-'r L
Since a phenomenon in which fine powder adheres to the surface of the -C roughness "L" also occurs, although there is an effect of increasing the overall average particle size, the effect of making the particle size uniform cannot be obtained.

In addition, 5 m
There is a method of classifying coarse particles with a size of 5 mm or more, pulverizing them to 0 or 25 mm or less, which makes it easier to granulate coarse particles with a size of 5 mm or more, and then adding it to the original raw material of 5 mm or less and granulating it with a drum, etc. Disclosed. This method also has the disadvantage that it is difficult to obtain the effect of uniformizing the particle size because the phenomenon of granulation of the fine powders and the phenomenon of adhesion of the fine powders to the surface of the coarse particles occur in parallel.

In such pre-processing methods proposed so far,
17. It was difficult to simultaneously achieve the two effects of improving air permeability by increasing the average particle size and uniformizing the air permeability by making the particle size uniform.

OBJECTS OF THE INVENTION The object of the present invention is to solve the problems of the prior art described above and to produce sintered ore with uniform quality and no uneven firing by using an appropriate pretreatment method for sintering raw materials.

Structure of the Invention According to the present invention, sintered raw material) l'4 is sieved through 1 mm and 5 mm sieves, fine particles of 1 mm or less are granulated to 5 to 1 mm, and coarse particles of 5 mm or more are crushed and further 1 mm and 5 mm. Provided is a method for producing sintered ore, characterized in that only raw materials having a particle diameter of 5 to 1 mm are sifted through a sieve and sintered by supplying them to a sintering machine.

That is, the present invention was developed as a method for improving the productivity, yield, and quality fluctuation of sintered ore, and it not only classifies the raw material charged to the sintering machine by the upper limit diameter, but also by the lower limit diameter. However, by classifying and controlling the particle size range to an appropriate value, it is possible to eliminate the mixed state of coarse particles and improve air permeability, thereby improving productivity, product yield, and quality fluctuations. The present invention provides a method.

The present invention will be explained below with reference to Examples, but it goes without saying that these Examples do not limit the present invention in any way.

Example First, three types of blended raw materials used in a normal sintering machine were dried and their particle size distribution is shown in Figure 3.
Q) The bottom Δ of the three types of raw materials is raw material 8 that is not subjected to classification treatment.
i; [, B has an average diameter of 1. '2mm and Δ are the same, but the grain size has been adjusted to 05-5mm, and C is ■3
and 1- The particle size ratio of the limit and lower limit is the same and the average particle size is 2.7 mm.
This has been increased to . The air permeability of these raw materials was evaluated using the apparatus shown in FIG.

In the figure, 13 is diameter 600fflLI + height 6 (10mm
cylinder, 10 is a wind box, 11 is 2 (1 mm thick bedding ore, 12 is a rosdol, 13 is a pressure gauge, 14 is a flow meter, 15
16 represents a wind blower, 16 represents a wind speed i-+, and the portion 17 was filled with the raw materials from above to C to a layer height of 5'80 mm, and the air permeability and wind speed distribution were measured. Note that the air permeability was calculated using the following formula ( ]).

10 Air permeability (, I P U ), Δ: Cylindrical cross-sectional area (m
'), ○: Air flow rate (m'/min, ), If: Raw material bed height (m), P' negative pressure (1ηΔq) Table 1 shows the measurement results of air permeability. From these results, it can be seen that the air permeability increases by reducing the particle size ratio to the lower limit (Zunawai particle sizing) and, at the same particle size ratio, as the average particle size becomes larger.

Moreover, FIG. 5 shows the measurement results of the wind speed distribution on the surface of the raw material. However, Fig. 5(a) shows the measurement position 1σ, and Fig. 5(b)
) indicate the measurement results at those positions. It can be seen that by decreasing the particle size of 2 and the lower limit by 1, variations in wind speed are reduced and uniform ventilation becomes possible.

The following are the results of cold measurements, but these effects are also considered to be effective in the hot sintering process, and we conducted a firing test to confirm these effects.

FIG. 6 shows the raw material processing flow during the firing test.

In the figure, 21 is a dry mulch machine, 22, 23, 24, and 25 are sieves,
26. 27 is a crusher, 2) is a pelletizer, 29 is a drum, and a mixer.

:30 does not indicate sintered steel. Also, as in Figure 2, ■ indicates iron ore, 2 indicates limestone, 3 indicates return ore, and 4 does not indicate coke.

The blending ratio of raw material 1゛ζ1 was 60% iron ore, 10% limestone, 20% return ore, and 1% coke, and this blending ratio was always kept constant and used as the blending raw material. If the diameter range is -1, the limit is 5 m, and the lower limit of m is 1 mm, 22, ?
3. The openings of the sieves 24 and 25 are 5 mm and 1 m, respectively.
m, l mm, 5 nun.

Note that the blended raw materials have a moisture content of 0.5% in advance in the dryer 21, and the raw materials supplied to the pelletizer 28 are such that the particle size of the granulated product from the pelletizer 28 is 5 to 11111.
It is a raw material that has been ground to a particle size of 0.25 mm or less, which is easy to adjust to TI.

Through the above processing flow, the particle size range was changed to 600 mm in diameter.
Made of sintered steel, bed height 600mm, suction negative pressure 1500mmA
Firing was carried out under constant q conditions.

The test results are shown in Figures 7 to 9, and they all show the influence of the particle size range (-limit particle size/de-limit particle size) on the product yield, production rate, and quality, respectively, in the -L limit particle size four parameters. it's shown.

From the influence of the coarse grain range on the product yield, which is not shown in Figure 7,
-1- It is clear that there is an appropriate value for the lower limit particle size ratio, and this appropriate value changes depending on the upper limit particle size.

If the particle size ratio is large, there will be uneven aeration due to the coexistence of coarse particles, while if the upper and lower particle size limits decrease too much, there will be insufficient melting as the entire raw material will become 111 particles. This is thought to be the cause of the -C yield deterioration.

Furthermore, when we look at the influence of the particle size limit under the minimum grain size specifications, the suitability for yield and the existence of an upper limit diameter (5 mm) are remarkable, and this is also due to uneven ventilation due to an excessively fine particle structure. This is thought to be due to insufficient melting due to coarse graining.

Next, let's talk about production efficiency.

Production efficiency is determined by the air permeability of raw materials and the product yield.31 As shown in Table 1, air permeability increases as the upper and lower limit particle size ratios become smaller, and under the same upper and lower limit particle size ratios, as the average particle size increases. That is, the larger the upper limit particle size, the better. Furthermore, the influence of the product yield shown in FIG. 7 is also involved, and the production efficiency shown in FIG. 8 is determined. From the viewpoint of air permeability, the smaller the particle size ratio and the larger the particle size, the better. 1' Efficiency should improve, but the effect of the product yield mentioned above is also strongly involved. There is a brain.

From the results in 1 below, it is clear that the appropriate upper and lower limit particle size ratio is 5.0 and the 100% grain size is 5 mm. Therefore, the appropriate i? It was confirmed that the diameter of the diameter was 5 to 1 mm.

Figure 9 shows the influence of upper and lower particle size limits on reducing quality variation, and it is clear that setting the lower limit particle size to 5.0 greatly reduces quality variation [1]. be.

The test results described above are an example in which all the raw materials of ore, limestone, return ore, and coke breeze were subjected to the preliminary granulation treatment shown in Figure 6, but if the particle size was 5 to 1 mm from the beginning. If the raw material brand is available, it is possible to omit the intermediate sieving, pulverizing and granulating steps and feed this raw material to the Doratomixie for mixing at the end.

Effects of the Invention According to the invention, the particle size of the raw material to be fed to the sintering machine is 5 to 1. m
When adjusted to m, unevenness in air permeability of the sintered layer on the sintering machine can be eliminated, and products with uniform quality can be produced with a high yield.

[Brief explanation of drawings]

FIG. 1 is a graph showing the particle size distribution of a sintered raw material before and after granulation treatment according to the prior art. FIG. 2 is a flowchart of a conventional sintering raw material mixing and granulation process. Figure 3 shows the sintering raw materials Δ, B, and C used in the embodiment of the wood invention.
It is a graph showing particle size distribution of. FIG. 4 is a schematic diagram of an apparatus for testing the air permeability of sintered raw materials. Figures 5(a) and (1)) show the measurement positions and measurement results of the wind speed distribution in the air permeability test of sintered raw materials. FIG. 6 is a flowchart of pre-treatment of sintering raw materials according to the present invention. FIG. 7, FIG. 8, and FIG. 9 are graphs showing the influence of -1- limit and lower limit particle size ratio on product yield, production efficiency, and drop strength, respectively. (Main reference number) l...Ore, ? ...Limestone, 3 ...Return ore, 4
・・・Powder Ni-J-kusu, 6.7 ・・・Rotating drum l, 8・
...zu, katsu+f='! ) number, 10...wind box, 16
... Wind speed 31, 17 ... Raw material layer, 21 ... Dryer,
22.23.24.25...Sieve, 26.27...Crusher 28...Pelletizer, 29...Driller, mixer 3
0... Sintered Steel Zej Patent Applicant Sumitomo Metal Industries Co., Ltd. Agent ㅅIX Masahiko Masahiko Arai (, fia) Figure 2 Gunmine 1) Figure 3 Figure 5α Credibility with Moxibustion Mask Figure 5b Figure 7

Claims (1)

[Claims] (1) Sieve the sintering raw material with 1 mm and 5 mm sieves, and granulate fine powder of 1 mm or less to 5 to 1 mm.
A method for producing sintered ore, characterized in that the above coarse particles are crushed and further sieved through 1 mm and 5 mm sieves, and only raw materials with a particle size of 5 to 1 mm are fed to a sintering machine for sintering. .