JPS60184642A - Manufacture of unfired lump ore - Google Patents

Abstract

PURPOSE:To manufacture easily unfired lump ore having superior strength and water resistance without carrying out sintering by mixing fine iron ore with cement and water, compression-molding the mixture into flakes, and curing the flakes. CONSTITUTION:Fine iron ore is mixed with cement and water, and the mixture is compression-molded into flakes of about 6-15mm. thickness with a pair of press molding rolls. The flakes are crushed optionally to about 10-50mm. grain size, aged for <= about 24hr, and charged into a blast furnace. Any of hematite, magnetite and limonite type fine iron ores may be used as said fine iron ore, and the preferred grain size is <= about 5mm.. Portland cement, mixed cement or the like is added as said cement by 2-8wt%, and water is added by 4-8wt%.

Description

[Detailed Description of the Invention] Technical Field> The present invention prevents scattering of powder when charging iron ore powder or iron oxide powder in a blast furnace, and maintains air permeability in the furnace for smelting. This invention relates to preliminary treatment of raw material iron ore powder to allow the reaction to proceed smoothly.

<Prior art> In recent years, the particle size of iron ore charged into blast furnaces has been becoming smaller due to demands such as increasing the pig iron production ratio or reducing the coke ratio. The amount of iron ore powder handled is increasing due to necessity, and dust collection is being strengthened to prevent dust pollution at pig iron factories, etc., so the use of iron ore powder is increasing. There is a tendency. Charging these iron ore powders into the blast furnace as they are causes poor or uneven ventilation, an increase in the amount of gas ash generated, and poor unloading, resulting in an increase in the coke ratio or a decrease in the tapping ratio. Iron ore powder must be agglomerated using an appropriate method because it has a significant negative effect on blast furnace operations.

The following methods are currently used industrially to agglomerate raw materials such as iron ore powder or iron oxide powder.

Mouth I Sintering method Iron ore powder of about 5-100 ml or less is mixed with coke of a suitable particle size and limestone powder if necessary, and 1200-1000 g
A method in which iron ore is calcined at a temperature of 400"C, a part of the iron ore is melted in a bath, sintered, and after cooling crushed to form suitable particles.

(2) Pulverized by Beretsutai Nong Gu Calcining Method: An appropriate amount of moisture and bentonite, lime, etc. are added to the ore powder as needed, and it is granulated using a rotating drum, two rotating plates, etc., and then calcined in a rotary kiln. A method to obtain sufficient strength by tying the knots together.

(3) Pelletizing - Cold hardening method A mixture of finely ground iron ore powder and Portland cement or Portland cement clinker powder is mixed with a mixture of iron ore powder and Portland cement or Portland cement clinker powder using a method commonly known as the cold bonding method, and the mixture is prepared using a rotating drum or rotating plate. A method in which the material is granulated using, for example, granules, and then cured to obtain sufficient strength.

Although it is roughly divided into the above three methods, methods +11 and (h) both use some method to add strength to the iron ore powder granules or pellets. is being fired.

This firing does not require large-scale equipment;
There is a phenomenon in which SOx, NOx, dust, etc. generated from the firing furnace become a source of pollution. For this reason, method (3) above has been developed as a non-fired agglomeration method, but method (3) has the following drawbacks and is still not sufficient.

b) Since it takes a long time (usually 7 to 10 days) to develop strength, large-scale curing equipment is required.

Since d-lets are spherical, their angle of repose is small, and when they are introduced into a blast furnace, they are unevenly distributed in the center of the furnace, making blast furnace operation extremely unstable. To avoid this, the amount used is limited to a very small amount (usually 10 to 20% by weight).

c) In order to achieve sufficient strength, it is necessary to add a large amount of cement (usually 7% or more), which increases the slag ratio during blast furnace operation, which reduces the tap iron ratio, coke ratio, and pre-furnace workability. etc. become worse.

2) Since the pellet is spherical and the reduction reaction proceeds topochemically, unreduced FeO tends to remain inside the pellet.

Po) 8! ! Since the raw material iron ore needs to be finely pulverized during the production process, the power cost for pulverization is low.

<Purpose of the invention> The present invention develops strength after forming without sintering in advance, has water-repellent properties, is resistant to reducibility in a blast furnace, and is capable of melting iron ore powder. It is an object of the present invention to provide a method for producing uncalcined agglomerated ore having sufficient strength to maintain its shape until it reaches a temperature using simple equipment.

<Configuration of the Invention> In order to achieve the above object, the configuration of the present invention includes compression molding a mixture of iron ore powder, cement, and water into flakes using a pressure molding roll, and then curing the mixture.

The iron ore powder used in the present invention may be hematite-based, magnetite-based, or limonite-based. Rutland cement, mixed cement, alumina cement or Portland cement clinker powder can be used.

The particle size of the iron ore powder should be smaller than the roll gap of the roll forming machine used, and is usually preferably 51III+ or less.

Next, it is preferable that the amount of cement that can be added to the iron ore powder as a binder is as small as possible, but if it is less than 2 weight, the cold southward strength will decrease, so it is not preferable.
In this case, even if more than this amount is added, the strength will not be improved so much, so the amount added is preferably 2% by weight or more and less than 8% by weight.

The iron ore powder, cement, and water may be mixed when the iron ore is crushed, or may be mixed using a common concrete mixer or the like.

The amount of water added to the mixture of iron ore powder and cement varies depending on the fineness of the iron ore powder, but the amount of water added to the mixture is 4M or more.
Less than 8% by weight is preferable; if it is less than 4% by weight, the cold drop strength of the unfired agglomerated ore is small, and if it is more than 8% by weight, the added water 9 will seep out of the molded product during molding. Not a drug.

When the mixed raw materials are compression-molded using a pair of pressure-forming rolls, a molded product is continuously produced in the form of flakes. Also, by changing the roll fJJ gap, the thickness of the υ flakes can be controlled. The thickness of the flakes is preferably 6 m or more and less than 15 m. If it is less than 6 m, the cold drop strength will be low, while if it is more than 15 m, the reducible properties of the uncalcined agglomerate will be poor, so these are not preferable.

If necessary, the molded product is crushed to a predetermined particle size using a crusher, approximately 10
After being crushed to ~50 mm, it is cured. For curing of the molded product, steam curing is preferable when charging the molded product into a blast furnace after curing for less than one day, and room temperature curing may be used when curing for more than one day. In addition, it is preferable that the edge 5, whether steam-cured or room-temperature cured, be subjected to forced drying at 100° C. or higher after curing. Forced drying is preferred because it increases the strength of the molded product and also reduces the amount of moisture entering the blast furnace.

<Effect of the invention> The present invention described above has the following advantages.

B. SOx is added to cold agglomerate iron ore powder.

Air pollution prevention measures against NOx and dust etc. [No measures are required.

B. Since it is manufactured in the form of flakes, the angle of repose is larger than that of conventional non-fired pellets, and the phenomenon of uneven distribution at high U=feeding can be prevented.

C. Conventional non-fired pellets can also significantly reduce curing time and suppress the slag ratio during blast furnace operation.

E. Conventional non-fired pellets can also reduce crushing power costs.

It has excellent reducibility and improves the smelting effect.

Experimental example Experimental examples of the present invention are shown below.

Experimental Example 1 Each level was made of 150 kp # of iron ore (hematite type) powder from Prasol Rio Doce, which was dried at 105°C and then crushed to a size of less than 1 pound, mixed with 1% to 10% by weight of early strength Portland cement. did. Thereafter, 100 g of the mixture and 6 g of water were mixed in a concrete mixer, and compression molded into flakes with a pair of pressure molding rolls.

1F = 1 and 7 at 20℃ relative humidity 80% or higher
After curing for a day, strong fall suction was measured according to JIS M8711, and the results shown in Figure 1 were obtained.

Roll diameter: 450mm Roll width: 300m + Molding pressure: 8
00~1000 kg/cyd! +, Figure 1 to light C)
It can be seen that when cement is added to iron ore powder, it is preferable to add 2% to 8% by weight.

Experimental Example 2 After mixing 941 parts of copper of Riodoce iron ore powder used in Experimental Example-1, 6 parts by weight of early-strength Portland cement, and 5 parts by weight of water in a pug mill, the same roll machine as used in Experimental Example-1 was used. Using J I S
The final reduction rate was measured according to MB 713, and the results shown in FIGS. 2 and 3 were obtained.

The thickness of the flakes formed from Figures 2 and 3 is 6.
It can be seen that a value of simple or more and 15 or less is preferable. That is, when it is less than 6 fins, the drop strength is low, and when it is more than 15 IaI+, the reducibility of the flakes becomes poor, which is not preferable.

Experimental example 3 Iron ore (hematite type) from Australia's Masley
The mixture was pulverized to less than 5 minutes, and then 6 wt. After curing the flakes under various conditions, the angle of repose, falling strength, final reduction rate, and maximum pressure drop value were measured.
I got the result.

For comparison, briquette machine molded products and unfired pellets (ordinary Portland cement IO, w-to--1.Uto-hJ+1=Kijima→+n1JspOutetsu QS2p
ie, crushed to a clear residue of 1.2% using a dish-type granulator 13-1
Granulation to a diameter of 5 mm) was also prepared and tested.

Table I M-shaped blade method and product yield It is clear that the roll forming method according to the present invention has a significantly high product yield.

II & steam curing, the test was discontinued because many cracks were generated on the pellet surface.

From Table 2, it can be seen that the cold drop strength of the EE@ molded products formed by the roll of the present invention is significantly higher than that of other molded products.

On the other hand, the effect of accelerated curing or long-term curing is small for products formed by briquette machines. This is thought to be because the non-uniformity of the molded product, which occurs because the molding pressure does not act uniformly on the molded product, is not resolved by curing.

Father, unfired pellets made of dish-shaped granules require 7 hours of curing at room temperature to achieve 95% drop strength.To shorten this time, steam curing at 80°C for 3 hours r#J+ results in the following results: mI
There is a problem that cracks occur and damage the product. However, the molded product of the present invention reaches a drop strength of 91% after 3 hours of steam curing at 80° C., making it possible to develop rice with high strength in a short period of time.

Next, looking at reducibility, compared to briquette machine molded products or conventional dish-shaped granules, the reducibility of the molded products according to the present invention is as clear from Table 3, with a final reduction rate of 9.
It can be seen that at 5%, the difference is quite large.1 This indicates that the molded product of the present invention has a f-77 lake shape, and its thickness is approximately 10%.
This is thought to be the result of the reduction reaction progressing to the inside of the reservoir, which is as thin as m. Moreover, the swelling index of the molded product of the present invention is the same as that of the conventional molded product, and it can be seen that there is no problem in this respect.

Table-4 Molding method and angle of repose Note) Measuring method of angle of repose: Sample (10-50 fine particle size)
30 k7 was placed in a 150 mφ cylinder, and the angle of repose after the cylinder was pulled out was measured.

Furthermore, the angle of repose was measured for the molded product of the present invention and the molded product of the comparative example. The results are shown in Table 4.

As is clear from Table 4, the angle of repose of the molded product of the present invention is larger than that of conventional molded products, and it is found that it is convenient when charged into a blast furnace.

Experimental Example 4 Iron ore (magnetite type) from Tatsusu, Canada was crushed into pieces of 1 m or less and made into ordinary SF Portland cement.

Mixture 1 after adding 5% by weight of 7% coke powder and mixing
After adding 6 parts by weight of water to 00 parts by weight and mixing with a 9-gum mill, the mixture was molded using the roll molding machine used in Experimental Example 1 at a molding pressure of 1500 k4/m. The thickness of the flakes was 13 mm.

Curing the molded product at room temperature for 1 day, steam curing at 80°C for 4 hours, and
After steam curing for 034 hours, the samples were cured at various levels of drying at 250° C. for 2 hours, and then the cold drop strength, final reduction rate, and blistering index were measured according to JIS, and the results shown in Table 5 were obtained.

Table 5 As is clear from Table 5, the final reduction rates in this experimental example were all 91 to 92%, indicating greater reducibility than the conventional one, as in Experimental Example 3. It can be seen that

Example 5 Iron ore from Robe River, Australia (limonite type)
pulverized to 3W or less, then early-strength Portland cement 2
5fold i%, 88μt! After adding and mixing 5 parts by weight of limestone powder and 11% by weight, add 7 parts by weight to 1 part iJ of water to 100 parts by weight of the mixture.
After mixing with a gum mill, the mixture was molded using the roll molding machine used in Experimental Example 1 at a molding pressure of 5001 f/m 2 . The flake thickness was 8.0 m.

Curing the molded product at room temperature for 1 day, steam curing at 90'C 2:11,
After steam curing at 90° C. for 2 hours and drying at 200° C. for 2 hours, the cold drop strength, final reduction rate, and blistering index were measured according to JIS, and the results shown in Table 6 were obtained.

Table 6 As is clear from Table 6, the final reduction rates in this experimental example were all 95% to 96%, and as in the case of Experimental Example 3, the reducibility was greater than that of the conventional method. I know that there is. It is also found that it is possible to develop short-circuit J strength by steam curing.

[Brief explanation of drawings]

1 to 3 relate to the molded product of the present invention, FIG. 1 is a graph showing the relationship between cement addition Ms and falling strength, and FIG. 2 is a graph showing the relationship between flake thickness and falling strength,
FIG. 3 is a graph showing the relationship between flake thickness and final reduction rate. Patent Applicant: Onoda Cement Co., Ltd. Nippon Steel Corporation Representative: Patent Attorney: Shibu Moto Ishi (and 1 other person) Fig. 1 Fig. 2: Flake thickness (mm) Continued from page 1 0 Inventor: Kenji Shima Onoda Tsuchi Oaza Onoda @
Inventor Akira Suzuki 5-chome, Tokai-cho, Tokai City 0 Inventor Junsuke Haruna 5-chome, Tokai-cho, Tokai City 0 Inventor Masami Fujimoto 6276 Edamitsu Steel Works, Hata-ku, Kitakyushu City Onoda Cement Co., Ltd. Company Chuoken 1-1-1
Nippon Steel Corporation Yawata

Claims (1)

[Claims] (11) A method for producing a non-calcined agglomerate, which comprises compressing a mixture of iron ore powder, cement, and water into flakes using a pressure forming roll, and then curing the mixture. (21) In the above mixture, the amount of cement added is 21-M
The method for producing uncalcined agglomerate ore according to claim 8r1.1, wherein the amount of water added is 4% to 8 times by weight.