JPS5881933A - Preparation of massivated iron ore - Google Patents

Abstract

PURPOSE:To obtain a product excellent in crushing strength and reducibility at a high temperature, when pulverized iron ore is formed into pellets or briquets useful in a blast furnace, by using phenol resin as a binder and heating the product at a specified temperature. CONSTITUTION:In making an iron source material useful in a blast furnace by forming pulverized iron ore into pellets or briquets, about 5% novolak-type phenol resin as a binder for the pulverized iron ore is added to and mixed in the pulverized iron ore, and the mixture is compression-formed into pellets or briquets. The product is cured by heating it at 130-280 deg.C. The obtained product is not pulverized in a blast furnace because of its high crushing strength at a high temperature in the blast furnace, but excellent in reducibility in the blast furnace since it has few closed pores.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing iron ore pellets (KII) or briquettes, in particular to a low temperature curing process using a phenolic resin as a new additive.

Conventionally, iron ore pellets or briquettes are manufactured by adding bentonite as a binder to fine ore mainly composed of less than 144 μm, and adding a small amount of water to granulate (or ml), and then producing raw pellets. Gradually dry,
The product is preheated and finally fired and hardened at around 1300"0.

However, since such conventional methods require preheating and firing at high temperatures, they require an enormous amount of fuel such as heavy oil and require large-scale equipment, which is economically disadvantageous. Because the pellets are mainly slab-bonded, they have many closed pores.For this reason, when these pellets are used as a raw material for blast furnaces, only the outer periphery of the pellets is reduced, and the ridge core is made up of unreduced wustite. There is a problem in that the residual amount remains, and the addition and use of bentonite also has the disadvantage that the amount of pulse failure increases.

The present invention was made with the aim of overcoming the above-mentioned conventional disadvantages and drawbacks, and is made by adding and blending a suitable amount of phenolic resin as a binder to concrete IL mold powder ore, granulating or forming it, and then forming a powder of 130 to 280 b. It is characterized by being heated and cured.

That is, as a result of various experiments and research, the present inventors have found that pellets made by adding phenolic resin to powdered ore (or briquette λ80 ~.ant+) instead of the conventional beretonite (or product pellets heated and hardened with briquette λ80 ~.ant+) are suitable for use in blast furnaces. It has been found that it maintains sufficient strength to withstand water and has excellent reducibility.

Hereinafter, the present invention will be described in detail, focusing on the experimental results of the present inventors.

First of all, the uninventor Go uses powdered iron ore (MBR) having the components listed in Table 1 as the main raw material, and adds Novo 2 Tsuku type phenolic resin powder (Ceradic 3337-8) to it (by weight). 2 tons of the added mixture was compressed using a die to form cylindrical briquettes with a diameter of 10 mm, a height of 5 mm, and the briquettes were maintained at a temperature of 150 t3 in the atmosphere for 2 hours. In addition to investigating the crushing strength of the product briquettes obtained in this way, the briquettes were further heated to 400 tons each in KN, assuming the usage conditions in a blast furnace. , 600
b, 800”C and Hi 1000t+ Chisel 1 degree?
The crushing strength was also measured for the samples held for 1 hour.

Table 112 shows the crushing strength test results of these phenolic resin-containing briquettes.For comparison, the same table also shows conventional briquettes based on the same raw material with 5m of bentonite added and 51s of PVA added. Similar test results for Bricella K are also shown.

@Table 1 Chemical composition of sample iron ore powder Table 2 Crushing strength (hg) of product briquettes From the results in Table 2, the phenolic resin-containing briquette according to the present invention has a high strength of 9292 kg during intermediate hardening, and after that it is Although the heat-treated material tends to decrease as the temperature rises, it has been found that even 1000'b has a strength of 34 kg, which is sufficient as a raw material for papermaking and blast furnaces. On the other hand, those with PVA added have a strong ijFilO after curing.
It can be seen that if the weight is extremely low (kg, 400 t) or more when reheated, it no longer has any strength and is completely unsuitable for practical use. In addition, 415 containing conventional bentonite
The strength at 0@O is as low as 6 kg, and the strength similarly disappears at 40G@O or higher.

Next, the present inventors used powdered iron ore with the same composition as in Table 1 as the main raw material, added 5% phenolic resin to it, and granulated it into pellets with a diameter of 13 mm using a pan pelletizer. This was then held at 150°C for 1 hour to harden, and the resulting pellets were placed in a reduction/testing apparatus, with a heating rate of 1d"O/min while supplying and discharging reducing gas.
heated to 1350"O, 950't3,1200t
Cough pellets at temperatures of l and 1350'b OO~*
The middle stage of so'b is a mixture of gases to 70QO-1-10C, and the late stage above 960°C is 4G'jQO+6ON,
A mixed gas of Table 3 shows the reduction rate of the pellets obtained in this reduction test.The same table also shows the pellets obtained by adding the same amount of PVA in place of the phenol resin for 5 hours and granulating them at 15Q"C. PVA-containing pellets and bentonite that have been hardened by heating and holding for an hour are added and granulated, then preheated and fired (firing temperature 1250 h) L
, 9 The same test results for conventional pellets are also shown. It should be noted that the PV pellets were agglomerated and powdered at 500b, making it impossible to measure the reduction rate.

Table 3 Reduction rate of product pellets (H) Therefore, from the results in the same table, it was found that the pellets according to the present invention have excellent reducibility. A remarkable difference can be seen when compared with In other words, conventional pellets have many closed pores because they have gone through a firing stage, and their reducibility has already deteriorated, resulting in high temperatures that may occur during papermaking. Due to its low melting point, the slag existing in the internal unreduced part elutes and blocks the pores, further promoting reduction stagnation, but in the case of the pellets of the present invention, the low temperature of around 150°C Since the pellets are hardened at high temperatures, there are very few closed pores and most of the pores are open pores, so reduction progresses better at low temperatures, and until the pellets reach high temperatures, the pellets remain open until a very small part of the center of the pellet is removed. This is because the reduction proceeds smoothly even in a high temperature range of 1200 m or higher, without clogging the pores by the low melting point slab.

Now, as mentioned above, the present invention involves adding and blending a phenolic resin to fine ore, granulating or molding it, and then heating and curing it at a low temperature.
Bg'b K must be maintained.

The reason for this is that at low temperatures below 130°C, the curing reaction by the phenol resin is insufficient, leading to a lack of strength in pine products.
Finally, at high temperatures exceeding 280°C, the resin burns and burns out due to oxygen in the atmosphere, and its strength decreases.

That is, Fig. 1 shows the raw materials in Table 1 added with 5 g of novolac type phenolic resin powder, which are similarly compression-molded to form cylindrical briquettes, which are 100"b, 12"b.
0t3. This is a graph illustrating the strength of product briquettes obtained by holding each temperature at 150°b, 2oob, aoob and 330°C for 2 hours. When the strength is 100 kg or more, it is found that the material has sufficient quality as a raw material for papermaking, blast furnaces, etc., but when it is outside the above range, the strength decreases significantly and it is found that it is unsuitable as the raw material.

Next, as for the phenol resin that is added after hardening, a novolac type (usually powder) was used in the embodiment, but a resol type (liquid) may also be used, for example. Furthermore, regarding the amount added, 5 to 10% (weight) of the total raw materials is particularly preferable. In other words, if the amount of phenolic resin added is less than 5%, the strength of the product due to the effect of the resin will be insufficient, making it unsuitable as a raw material for blast furnaces.On the other hand, if the amount of phenolic resin added exceeds 10%, If the iron content is relatively reduced and disadvantages such as reduced reducibility are caused, it becomes K.

As described above, according to the present invention, conventional preheating is performed.

This invention eliminates the need for a sintering process and allows the production of superior quality agglomerated ore with sufficient strength and high reducibility as a raw material for blast furnaces, etc., and is an extremely beneficial invention from an economic and technical perspective. It can be said that

[Brief explanation of drawings]

FIG. 1 is a graph illustrating the relationship between temperature conditions and strength of agglomerated ore according to the present invention. Patent applicant Kobe Steel, Ltd.

Claims (1)

[Claims] A method for producing n-ore agglomerates, which comprises adding and blending an appropriate amount of phenolic resin to fine ore powder, granulating or molding the mixture, and then heating and hardening the mixture with 13 G-280'O.