JPS60138020A - Production of raw material to be sintered - Google Patents

Abstract

PURPOSE:To produce sintered ore having high quality with a reduced cost by using pulverous powder after screening and granulating in the stage of using high alumina contg. powder iron ore having hard sinterability as a raw material for the sintered ore. CONSTITUTION:Powder of the iron ore which contains much Al2O3 and is hardly sinterable is stored into a bunker 2 by a belt conveyor 1a. Such iron ore is screened by a screening machine 3 having 2-4mm.phi mesh. The oversized ore is fed directly to a mixer 4 and the undersized pulverous powder is fed to a kneader 5 where water is added thereto and the powder is kneaded and thereafter the kneaded powder is fed to a granulator 6 such as a pan pelletizer or the like. Water is further added to the granules if necessary and the ore is granulated to 2-5mm. pseudo particles which are then fed to the mixer 4. Raw materials such as crude granular iron ore, returns, quartz stone, serpentine, coke, etc. are charged from bunkers 20 into the mixer 4, by which the materials are thoroughly mixed and thereafter the mixed materials are fed to the bunker of a sintering machine. The sintered ore having high quality is produced by using the pulverous iron ore of high alumina type having hard sinterability.

Description

[Detailed description of the invention] Technical fields> The present invention relates to a method for producing a sintered raw material.

<Technical Background and Prior Art> As is well known, sintered ore is produced by mixing powdered iron ore (hereinafter referred to as powdered ore) with auxiliary materials such as limestone, serpentine, and iron sand, and coke powder. The raw material that has been pre-treated for granulation is charged onto the grate of a sintering machine, and the coke formed on the surface of the raw material on the grate is ignited and fired. In recent years, there has been a tendency for the above-mentioned fine ore to have a high alumina (A/, os) content, for example. Although the price of such high A/2o3 fine ore is low, it has poor sintering properties even if it is subjected to all the general pre-treatments mentioned above, and it causes various problems such as lowering productivity and deteriorating the quality of sintered ore. There were problems and many restrictions on its use. Therefore, the present inventors have developed the above-mentioned high A403-containing fine ore (
In order to effectively use sintering materials (hereinafter referred to as difficult-to-sinter materials) as sintering materials on an industrial level, we have repeatedly conducted various experimental studies. As a result, it was found that it is extremely effective to pre-granulate only the fine ore powder to form pseudo particles among the powder ore particles, and then mix it with other raw materials. By the way, the technique of granulating the fine powder ore is disclosed in, for example, Japanese Patent Publication No. 39-1801 and Japanese Patent Application Laid-Open No. 1423-1983.
This method has already been proposed by No. 01 and others. However, in the techniques proposed in Japanese Patent Publication No. 39-1801 and Japanese Patent Application Laid-Open No. 53-142301, it is difficult to sinter the particle size as it is, or it has an unfavorable influence on sinterability.

or 0.7 wx J21. Is it possible to pre-granulate the ultrafine ore below and make it into a lump of a predetermined size or more? It was just something that made it seem possible.

<the purpose> The present invention further improves the method for producing the pseudo-particles.

The object of the present invention is to provide a method for producing a sintered raw material that increases the usability of the difficult-to-sinter raw material and allows production of high-quality sintered ore with less energy consumption and at a lower cost.

Structure and operation> The gist of the present invention is to perform sieving using powdered iron ore of 2 to 4 Mφ as a reference, and to transform the fine particles of ili'F into pseudo particles with a particle size of 2 to 5 uφ, and then to remove the coarse particles and the coarse particles on the sieve. The purpose is to mix it with other raw materials to produce pseudo-granule t-S for sintering raw materials.

By the way, as mentioned above, there are many restrictions on the use of raw materials, which have been categorized as difficult-to-sinter materials.
First of all, as a result of research, high AI! Even in z03-containing fine ores, there is AI in the fine powder, which is said to be directly involved in the production of melt during the sintering process! It has been found that higher operating systems have many negative effects. That is, AI in the fine powder!
When the amount of fine ore with a high 203 content is increased, the RDI (reduction index a) deteriorates under high heat levels, and conversely, productivity and SI (fall strength) decrease under low heat levels.

On the other hand, sintering raw material (the raw material after pre-treatment of mixing and granulating the aforementioned powdered ore, auxiliary raw materials, coke, etc. is hereinafter referred to as sintering raw material, and the raw material before pre-treatment is simply referred to as raw material) It is well known that when the pseudo-graining condition is expressed by the pseudo-graining index (hereinafter referred to as GI) shown in the following equation (1), when the GI improves, the air permeability and the sintering rate improve.

GI=(A1-”+A snow-B2)xloo (1)
AIA.

GI: Pseudo-granulation index Al: Proportion of 0, 5 to 025 u in the particle size distribution of pseudo particles (weight ratio) Al: Proportion of 0, 25 u or less in the particle size distribution of pseudo particles (weight ratio) B1: True of pseudo particles Ratio of 0.5 to 0.25 U in particle size (weight ratio) B snow: Ratio of 0.25 U or less in true particle size of pseudo particles (weight ratio) Therefore, the present inventors investigated the properties of pseudo particles and sintered ore. We investigated the relationship between drop strength and yield, etc.

Figure 1 shows the production process by mixing powdered ore with an average particle size of 2 to 3Uφ or less as shown in Table 1 below with other raw materials (pulverized ore powder, auxiliary raw materials, coke, etc.) and then varying the amount of water added. The granulated pseudo-particles were sintered using a pot tester to investigate the drop strength (8I), air permeability before ignition (JPU), sintering speed, and product yield. It is something.

Table 1 In Table 1, the content of A/203 in the fine particles of 0.5 ag or less was 2.1% for the sample work, and 2.
．． 5%, which corresponds to sample (1) using a large amount of the above-mentioned difficult-to-sinter raw material.

From FIG. 1, it can be seen that when the amount of water added during granulation is increased, the GI is improved, and the permeability before ignition and the sintering rate are also improved accordingly. This is because the number of fine particles in the sintering raw material decreases, and as mentioned above, it has been generally known in the past. The aim is to improve However, there is an optimum moisture range for drop strength and product yield, and this almost coincides with the range in which the content of pseudo particles of 2 to 5 Mφ in the sintering raw material is maximum. In other words, new findings were obtained from the above examples that by increasing the content of pseudo particles of 2 to 5 diameter in the sintering raw material, the drop strength and yield of finished products were improved for both pigments I and II. Now, FIG. 2 shows a better granulation property than that shown in FIG. 1. or.

It is well known that the granulation properties of fine particles are better than those of coarse particles when using the same raw material.

Therefore, the present inventors sieved Hamasley, which is one of the high ki203-containing ores, using a Senrokugozo sieve 3 as shown in FIG. 3, and made the fine particles under the sieve into pseudo particles using a pan pelletizer 60. Thereafter, the particles were combined with the coarse particles on the sieve and the particle size distribution was measured.

Is Figure 4 an example of the measurement results? It shows.

(a) in FIG. 4 is a pan pelletizer 6°051
/hour, and as the capacity per pan pelletizer 60 increases, the granulation time becomes shorter. From FIG. 4, when the sieving standard was set to 2 to 4 Mφ, the proportion of pseudo particles of 2 to 5 u could be reduced to 60% or more, and the proportion of fine particles of 2 u or less to 20% or less. In particular, it was confirmed that those sieved on the basis of 3Hφ exhibited excellent effects regardless of the length of the granulation time. Next, various fine ore f 3 m
The particles were sieved using the f standard, and the granulation properties of fine particles with a diameter of 3 mm or less were investigated. Figure 5 shows an example of the survey results.
/2o3-containing ore is blended with the above-mentioned Hammersley, Mt.
2 mφ or less), falling collapse rate (pseudo particles 1.5
The percentage of pseudo particles disintegrated when dropped three times from a height of m) and the moisture content during powdering are shown, respectively. Figure 5+al is a combination of Hammersley and other fine-grained ores, Figure 5 (bl is a mixture of Mt. Newman and all other fine-grained ores, and when granulated under optimal moisture, it is a single fine-grained ore containing high A/2O3. However, it was superior to other fine-grained ores in terms of granulation properties and falling disintegration rate.

Now, of the raw materials shown in Table 2, Rope River F
, 1vlt Newman FI Hamasley Fvi#3關φ
After sieving based on the sieve and mixing the fine particles under the sieve, that is, 311aφ or less, to obtain pseudo particles of 2 to 5uφ,
The pseudo-particles are coarse particles having a size of 3 or more diameters on the sieve and the above-mentioned Roblino-F, Mt.

Newman F, Hamasley Ft - Removal The resulting particles were hereinafter referred to as pseudo-grain agglomerates). In this example, for the raw materials shown in Table 2, coke powder was 3.
1% was added.

FIG. 6 shows the investigation of the particle size of the pseudo-granules. Based on the present invention, when only fine particles of 3wφ or less were made into pseudo-particles in advance, 2 to 5
I was able to increase the 111 go of the cabinet to over 50%. On the other hand, when all raw materials are mixed at the time of tltJ using the conventional method, even when mixed for 6 minutes (Comparative Example ■), the percentage is at most 40%, and when mixed for 3 minutes (Comparative Example ■), the percentage is 40%.
%.

Furthermore, as mentioned above, the pseudo particles have a high water content of 8 to 9%, but when mixed with other raw materials with low water content, the water content as a sintering raw material becomes 6 to 65%. Fig. 7 shows the results of investigating the SI, RDl, production rate, etc. by sintering the pseudo grain agglomerates using a pot testing device. As is clear, by implementing the present invention, SI, product yield, RDl,
Excellent effects incomparable to conventional methods were confirmed in terms of production rate, JPD, etc.

As described above, the present invention sieves fine ore based on a preset sieving point within the range of 2 to 4 uφ, and granulates the fine particles under the sieve under optimal moisture. After forming pseudo particles with a diameter of 5 mm, they are mixed with the coarse particles on the sieve and other raw materials such as auxiliary raw materials and coke, and then granulated to produce pseudo granule agglomerates. Therefore, in the present invention,
The entire amount of powdered ore used as a sintering raw material is subjected to the sieving described above, and the fine particles under the sieve are made into pseudo particles of 2 to 5Hφ (by performing the sieving, the fine particles under the sieve are made into pseudo particles) (hereinafter referred to as one-selective granulation), but according to the experience of the present inventors, when a difficult-to-sinter raw material is not used, as the amount of the selectively granulated pseudo-particles increases, the present invention The above-mentioned functions can be further enhanced. However, high A
/xo, since the contained sintering-resistant raw materials have various problems as mentioned above, in order to fundamentally solve these problems, at least 15% of the amount of flame-retardant raw materials used is %
It was necessary to selectively granulate the above.

<Examples> Next, specific examples of the present invention will be described. FIG. 8 is an equipment flow diagram showing an embodiment based on the present invention.

In this embodiment, fine ore is transported via a belt conveyor 1a and stored in a dump truck 2. The fine ore cut out from the bunker 2 is sieved by a sieving machine 3 according to a preset sieving standard.

In this embodiment, by replacing the sieve mesh of the sieve separator 3, the sieving reference point can be changed to 2 to φ, 3 W φ, and 4 W φ. The sieving can be carried out using the optimum sieving criteria according to the situation. Of the fine ore sieved by the sieving machine 3, the coarse particles on the sieve are
It is fed directly to the mixer 4. On the other hand, the fine particles under the sieve are kneaded in a kneading machine 5 while adding moisture, and then granulated in a granulator 6 such as a pan pelletizer while adding moisture as necessary to become pseudo particles of 2 to 5M. . The pseudo particles are combined with the coarse particles on the sieve, or are fed to the mixer 4 independently from the coarse particles, although not shown. Auxiliary raw materials such as limestone and serpentine, coke powder, and the unsifted ore powder are fed from the belt conveyor 1b to the mixer 4 via the bunker 20. In the mixer 4, the pseudo particles are mixed with the coarse particles on the sieve and other raw materials that do not pass through the sieve separator 3, and are granulated to form pseudo granule agglomerates for sintering raw materials, which are then sintered. It is sequentially fed to a binding machine (not shown).

Now, the present invention is implemented in the equipment shown in FIG. 8,
The produced sintered raw material was supplied to a DL sintering machine having an effective sintering area of 183 m to produce sintered ore. Table 3 shows the blending ratio of the sintering raw materials used in this example, and the selective granulation was performed on the fine ore shown in Table 4 using 3 ml ψ as a standard.

Table 3 After classification Table 4 Also, during the selective granulation, 1 limestone fine particles were also added and mixed. As a result, based on the present invention, quicklime'i0.
3%, coke powder can be reduced by 0.08,
Furthermore, 8I could be maintained at 86.5% (comparative example: 87.0%)1 under high production conditions with a production rate of 39.5 and a ton/rr of 1724 hours.

<Effects> The present invention can be implemented without reducing the amount of coke or limestone added without reducing the quality or productivity of sintered ore. Sinterable raw materials can now be actively and effectively used as sintering raw materials. As a result, the manufacturing cost of sintered ore was also significantly reduced.

[Brief explanation of drawings]

Figure 1 is a graph showing the results of sintering tests conducted with various moisture contents during granulation of fine ore, Figure 2 is an enlarged graph showing the granulation properties of Figure 1, and Figure 3 is the experimental equipment. 4 is a graph showing the measurement results of the particle size distribution of the raw material obtained with the apparatus shown in FIG. 3. FIG. FIG. 6 is a graph showing the investigation results of the particle size of pseudo-granules. FIG. 7 is a graph showing the results of sintering tests of pseudo-granules obtained by the method of the present invention and the conventional method.・Me + zJ Midori ni Sutenge < -f, fr town p・J number fight 20
-With my eyes... Agent: Patent attorney Masaaki Akizawa, Hikaru, and 2 other people, Makoto Makoto 8 Ai@kozen 2 7 notes IN,. 1. Indication of the case Japanese Patent Application No. 1982-247215 2. Name of the invention Process for producing sintered raw materials 3. Person making the amendment Applicant related to the case Address (residence) 2-6-3 Otemachi, Chiyoda-ku, Tokyo No. Name (665) Nippon Steel Corporation 4, Agent
Location: 12-1 Taiyo Building, Kabutocho, Nihonbashi, Chuo-ku, Tokyo, 5, tlu#□E13,111. Date of Showa year month
Date (Shipping) (υ Correct the statement "Iron ore powder 2-4Wφ" in the 8th line from the bottom of page 3 of the specification to "Iron ore powder 2-4Nφ". (2)・Page 8, line 7 of the specification (3) On page 9, line 4 of the same page, correct the phrase "at the time of powdering" to read "1 at the time of granulation." On the 3rd line from the bottom of page 11, correct "rJPD, etc." to rJPU J. (5) On page 177, line 6, correct the statement "sI is also 86.5%" to read "rsI is also 87.6%." (6) Table 3 on page 15 of the same page is corrected as follows: 1. Name of the case: 1. Name of the case: 1. λq7.lambda. Relationship with

Claims (1)

[Claims] (1) Sieve powdered iron ore based on 2-4Hφ,
After making the subsieve fine particles t1 pseudo particles with a particle size of 2 to 5 φ,
A method for producing a sintering raw material, characterized in that pseudo grain agglomerates for a sintering raw material are entirely produced by mixing together with the coarse particles on the sieve and other raw materials.