JPH08176688A - Production for sintered ore - Google Patents

Abstract

PURPOSE: To improve the yield, productivity and property to be reduced of sintered cores by mixing pisolite cores as a raw material behind a granulating mixer. CONSTITUTION: The total pisolite cores in an amount of 70-80wt.% are granulated together with iron cores 2 as a raw material exclusive of the pisolite ore, limestone 4, serpentine 5 and coke 3 in a drum mixer 9 and, thereafter, the remaining 20-30wt.% of pisolite cores 1 are mixed therewith and the mixture is charged into a sintering machine 11 through a raw material hopper 10 to sinter the mixture as a sintered cores-production method in which 30-50% of the raw material iron cores are pisolite cores. In this way, by improvement of the yield, productivity and property to be reduced and reduction-powdering resisting strength, improvement of quality of the sintered cores, stabilization of operation, and further, reduction of operating cost are attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a sinter, which is a main raw material for blast furnace steelmaking.

[0002]

2. Description of the Related Art Pisolite ores have a high assimilation rate during the sintering process. The reason for this is that the assimilation reaction is C at around 1200 ° C.
Since the aO.Fe ₂ O ₃ system melt is generated and the iron ore is melted in this melt, the assimilation rate of the pisolite ore that has become porous due to the decomposition of goethite becomes faster.

As a result, an over-melted state occurs in the sintered layer,
It impairs the air permeability of the sintering, causing a decrease in productivity and a decrease in yield. The countermeasure is to suppress assimilation with the melt.

A method for suppressing assimilation by attaching serpentine to the surface of a pisolite ore disclosed in Japanese Patent Laid-Open No. 03-047927, and Japanese Patent Laid-Open No. 03-1303.
There is a method in which the pisolite ore disclosed in Japanese Patent No. 26 is heated and densified in advance and then sintered.

[0005]

However, these techniques require a facility for granulating pisolite ore and serpentine in advance in the former, and a heating furnace for preheating in the latter, both of which are manufactured. There is a problem of high cost.

Pisolite ore is granulated in advance,
There is a technology to secure air permeability by confining the melt in cracks of pisolite ore (Materials and Processes, 199
4. VOL7,993), which is similar to the above method,
The goal is only to improve breathability, and these technologies cannot be expected to improve reducibility.

As described above, in all of the conventional methods, the manufacturing cost of the sinter becomes high and the reducibility cannot be improved.

According to the present invention, the pisolite ore is mixed after the granulation mixer to suppress contact with the CaO source, and the mineral structure of the sinter becomes a needle-like calcium ferrite bond. Provided is a method for stably producing a sintered ore by improving productivity and reducibility.

[0009]

According to the present invention, in a method for producing a sintered ore in which 30 to 50% of iron ore raw material is pisolite ore, 70 to 80 wt% of the entire pisolite ore and iron ore raw material excluding pisolite ore are used. , Limestone, serpentine and coke are granulated, and then the remaining 20 to 30 wt% of pisolite ore is mixed, charged into a sintering machine, and sintered to produce a sintered ore. is there.

[0010]

The operation of the method for producing a sintered ore according to the present invention will be described below together with the operation.

Generally, 5 m for iron ore of 10 mm or less
Add limestone of less than m, silica stone and serpentine, and add basicity (C
aO / SiO ₂ ) = 1.8 to 2.0, SiO ₂ = 5.3
Approximately 4% by weight of the new raw material with the ingredients adjusted to 5.5%
Add 5% to 5% coke of 3 mm or less and 6 to 7% water and mix and granulate with a drum type mixer. The granulation time at this time is about 3 to 5 minutes.

Here, the ore of 1 mm or less adheres to the surface of the ore of 1 mm or more serving as the nucleus, and particles having a double structure are produced. This is called a pseudo particle. The pseudo particles are filled in the pallet of the sintering machine. The packing density at this time is 1.8 t / m ³ . The raw material layer thickness is about 500 mm. Coke is ignited on the surface of this raw material with an ignition burner, and a sintered ore is manufactured while sucking with a blower from below.

A problem when using pisolite ore is that since a large amount of goethite (Fe ₂ O ₃ .2H ₂ O) is contained, bound water evaporates during heating and a huge crack occurs at the goethite portion. In the sintered layer, the initial melt starts to be generated when the temperature is 1200 ° C. or higher. The melt penetrates into the cracks,
Since the assimilation of the ore is promoted, the inside of the layer is over-melted and the ventilation is obstructed during the sintering operation.

As a result, the sintering rate is lowered and uneven burning occurs. The former lowers productivity and the latter lowers yield. In order to suppress such assimilation of ore, it is most effective not to contact the pisolite ore with the melt during sintering. The present invention relates to pisolite ore and Ca
This is a manufacturing method in which contact with the O source is avoided as much as possible.

FIG. 1 shows an example of the granulation flow of the present invention. First, 20 to 30 wt% of pisolite ore 1 is separated by a separator 6, and the remaining 70 to 80% of pisolite ore is mixed with other ore 2, coke 3, limestone 4 and serpentine 5 in a drum mixer 9 and granulated. .

The granulated material is conveyed by the belt conveyor 8 to the hopper 1
0 is charged into the hopper 10, but the pisolite ore sent from the belt conveyor 7 of another system before the charging is charged into the conveyor 8 and lightly mixed on the conveyor, and then both are charged into the hopper 10. Charge. The raw material cut out from the hopper 10 is charged into the sintering machine 11 according to the amount of sinter production at that time.

This granulation flow is about 32 t / d / m ²
It is adjusted to a production amount of more than 35 t / d / m ² or less, but the reason why the ratio of the pisolite ore mixed after granulation is preferably 20 to 30 wt% is 30 wt%.
If the content exceeds 20%, segregation of the pisolite ore occurs in the hopper, causing uneven burning. If the content is less than 20 wt%, the yield, tumbler strength (T.
This is because the effect on I) and the like is small.

Next, the filling state of the raw material in the sintered layer after the raw material treatment in the sintered bed layer is shown in FIG. 3, in which the limestone 4 which is the CaO source is granulated with another ore 2. Pisolite ore 1 fills the space between the granules.
The basicity of a usual granulated product is about 1.8 to 2.0,
Since this granule normally takes in the limestone component attached to the pisolite ore, the basicity has risen to nearly 3.0.

The structure of the sinter having a basicity of 2.0 in the normal state is a structure mainly composed of porphyritic hematite and silicate slag. Such a structure has reduced reducibility. Further, the assimilation structure of pisolite ore produces a large amount of pores and forms a spongy fragile structure structure, which causes a decrease in yield and strength.

On the other hand, when the basicity is close to 3.0, the viscosity of the melt is lowered and needle-like calcium ferrite (CF) is likely to be produced. Needle-like CF is Ca in a short time of about several seconds.
Since it is generated by the solid-liquid reaction between O and iron oxide, the amount of the permeation of the melt into the pisolite ore is reduced and assimilation is suppressed.

Since the pisolite ore has a porous structure, it is useful for improving the reducibility if it is left without being assimilated. In addition, it has been confirmed in an actual machine test that sinter ore mainly having an acicular CF structure has improved productivity, yield, reducibility and strength (iron and steel: 1985, VOL71, A193).

As described above, in the present invention, productivity, yield, and reducibility are improved by mixing a part of pisolite ore from the normal raw material granulating step after the other raw materials are granulated and sintering. Improve and produce sinter with high cold strength.

[0023]

[Examples] Fig. 2 shows a tumbler strength (T · T) against the ore ratio when the pisolite ore mixed after granulation is mixed at a ratio of 0 to 45 wt% by a 50 kg sintering pot test.
I), the production rate, and the result of measuring the yield are shown.

The compounding raw material is 30% by weight of pisolite ore,
Other ore 40wt%, the rest is limestone 20wt% and serpentine 10wt%, the basicity of the whole raw material is set to 2.0 according to the site operation, and the coke is 4 with respect to the above total.
It was set to wt%. The proportion of pisolite ore mixed after granulation is 20 to 30 wt%, which improves yield, production rate and strength,
In particular, it showed the maximum value when 30% by weight of pisolite ore was mixed.

From this, it was found that it is preferable to mix at least 30% or less of the pisolite ore after granulation. This is because if it exceeds 30%, segregation of the pisolite ore occurs in the hopper, and the ideal packing structure is not obtained.

FIG. 4 shows an example in which the present invention is applied to actual machine operation. In this test, 30% of pisolite ore was mixed after granulation. As a result, application of the present invention improved the yield by 5.5 points, the production rate by 6 t / d / m ^2, and the tumbler strength by 2.5 points. Reduction powder resistance (R
DI) improved by 4 points.

[0027]

As described above, by applying the present invention, the pisolite ore in the iron ore is set to 30 to 50 wt% and the ratio of the pisolite ore mixed after granulation is 20 to 20%.
By setting the content to 30 wt%, the yield, the productivity and the reduced rate can be improved, and the reduction pulverization resistance can be improved, so that the quality of the sinter ore and the stable operation of the sinter can be enjoyed. It is possible to further reduce the operating cost.

[Brief description of drawings]

FIG. 1 is a drawing showing an example of a raw material processing flow of a method for producing a sinter according to the present invention.

FIG. 2 is a drawing showing the relationship between the proportion of pisolite ore that is mixed in after the raw material is granulated and the ratio of TI, production rate, and yield.

FIG. 3 is a drawing showing a filling structure of a raw material in a sintered layer after the raw material is processed by the manufacturing method of the present invention.

FIG. 4 is a drawing comparing the RDI, production rate, yield, and strength of sinter before and after application of the present invention in actual machine operation.

[Explanation of symbols]

 1 Pisolite Ore 2 Other Ore 3 Coke 4 Limestone 5 Serpentine 6 Separator 7,8 Belt conveyor 9 Drum mixer 10 Raw material hopper 11 Sintering machine

Claims (1)

[Claims] 1. A method for producing a sintered ore in which 30 to 50% of iron ore raw material is pisolite ore, and 70 to 80 wt% of the entire pisolite ore, iron ore raw material excluding pisolite ore, limestone, serpentine and coke. After granulating
A method for producing a sinter, comprising mixing the remaining 20 to 30 wt% of pisolite ore, charging the sinter, and sintering.