JPS58199829A - Manufacture of uncalcined lump ore - Google Patents

Abstract

PURPOSE:To provide prescribed hardness by molding iron ore contg. a specified amount of grains having a specified grain size and aging and hardening the molded ore in satd. steam at a specified temp. or in the air at ordinary temp. in a state where external force causing cracking and breaking such as impact force or pressurizing force is not applied. CONSTITUTION:A binder is added to iron ore contg. 10-80% grains having 1- 10mm. grain size. Water is optionally added, and >=1 kind of substance contg. a reducing agent or an oxide such as CaO, SiO2 or MgO may be added furthermore. They are molded, and the resulting lump material is aged and hardened in satd. steam at 20-90 deg.C or in the air at ordinary temp. for >=2hr in a state where external force causing cracking and breaking such as impact force or pressurizing force is not applied to the lump material immediately after the molding. The lump material is then aged under known conditions until prescribed strength is obtd., and it is dried and crushed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing unfired agglomerated ore used in a blast furnace, and aims to improve the yield of unfired agglomerated ore and prevent quality deterioration.

A typical example of unfired agglomerate ore used in blast furnaces is cold bond pellets, which are made by adding a hydraulic binder (usually cement) and appropriate moisture to fine ore powder. In other words, the conventional cold pond benz) is made by adding cement and water to powdered ore having a particle size of 4 or less, then mixing it, forming it into paper and granulating it using a pelletizer or briquette machine, After curing and hardening in a furnace etc., it becomes strong enough to be used as a blast furnace charge, and then used as a blast furnace charge.

However, the uncalcined agglomerated ore produced by such a method has the disadvantages of (1) a small angle of repose due to its shape and uneven distribution in the blast furnace, and (2) poor high-temperature properties. As a countermeasure for (2), there is a method of improving the shape by crushing, which is commonly used in fired pellets, but it tends to be smaller as a blast furnace charge and is easier to powder. , shape improvement by crushing was not desirable. In addition, as countermeasures for (2), methods to improve gangue composition and methods to improve reducibility are known, but the former method
The latter method reduces cold strength,
There were problems such as powdering during reduction.

As a method to solve these problems, the present inventors proposed the following method for producing uncalcined agglomerate ore.

This method involves adding a binder and water if necessary to iron ore with a particle size of 10cm or less and 1m or more, and adding a solid reducing agent, CIO, Sing, 14g if necessary.
In this method, one or two or more substances containing oxides such as 0 or the like are added, and after molding, curing and hardening are performed to produce a non-calcined agglomerate. This method allows the use of relatively low-grade ores, provides a large angle of repose and good gas flow, and produces uncalcined agglomerates with good high-temperature properties. It is very good in terms of its advantages. However, this method uses coarse-grained ore, which tends to cause cracks and breakage after molding; ■Conventional pellets and briquettes have highly filled surfaces and are strong, but this method makes it evenly formed! Since the weight of one piece is larger compared to Glycera F, when handled and cured in the same way as conventional Pelletz F, briquettes, etc., in other words, some impact force When stress such as pressurizing force is applied, cracks and destruction occur, resulting in a decrease in product yield II and deterioration in quality O. Therefore, it is necessary to adopt a different method for curing in this method of manufacturing uncalcined agglomerate ore than that used in the conventional Beret F medium and Purikat F method.

This invention was made to meet these demands, and its gist is that the particle size is 10M or less and 1m or more is 1m or more.
0-8.- Add a binder and water if necessary to the iron ore containing, and if necessary, a solid reducing agent.

Adding one or eight or more substances containing oxides such as Cab, Si(%), M(O), curing and hardening after molding,
In the method of manufacturing non-calcined agglomerated ore, the agglomerate immediately after being formed is placed in saturated steam at a temperature of 20 to 90°C or in room temperature air without applying external forces such as impact force or pressure that may cause cracks or destruction. A method for producing a non-calcined agglomerate is characterized by curing and hardening for at least 2 hours or more.

This invention method will be explained in detail below.

First, the reason for limiting the raw material ore in the method for producing uncalcined agglomerated ore, which is the object of the ζO invention, will be explained. That is, in the case of cold bond ore, ores of 0.5 to 1 cm or less react with the cement F1 auxiliary material and form a uniform molten structure, but ores of 1 mg+ or more remain in the 11 state,
It hardly contributes to softening shrinkage. The reason for this is that the reaction between ore grains and cement t occurs on the surface, and the 7-men 1) II formation does not diffuse into the interior of the ore, and the amount of gangue in the ore is small. When we change the amount of ore that reacts with this cement and examine the high-temperature properties, we find that if the ore contains particles with a particle size of 1 m or more and 10 or more, it is considered to be a normal blast furnace raw material, as shown in Section 1II. Equivalent softening properties can be obtained. In addition, when examining the relationship between the amount of ore at one or more locations and the rotational strength, we find that
As shown in FIG. 2, if the ratio of ore grains with a diameter of 1 or more exceeds 80, the rotational strength of the target value of 85, which can withstand practical use, becomes lower than 85, making it impractical. The reason for this is presumed to be that, while the high-temperature properties become better as the ratio of ore grains of 1 m or more increases, the filling properties deteriorate as fine ore decreases.

For the above reasons, we use powdered ore containing 10 to 80 ore grains with a particle size of 10111 or less and 1 m or more in diameter. This is because ores larger than ioms do not need to be agglomerated in any way.

Next, the curing conditions of the ζO invention method KJiP key will be explained. The inventors believed that the crushing yield of uncalcined agglomerate ore indicates stability against impact force and pressing force, and investigated the relationship between the rotational strength index and the crushing yield.

As a result, as shown in Figure 3, the crushing yield of non-calcined agglomerate ore increases as the strength O decreases, and when external force is applied to this non-calcined agglomerate at low strength, the yield decreases. It was found that this caused a decline in quality. In addition, as the target yield, aOs
If you adopt this, you can understand that it is only necessary to cure it in a situation where no external force is applied and the rotational strength index becomes 40 or more.

It is known in the field of regular concrete and concrete that the strength of cement hardened products changes depending on the curing conditions, so the relationship between curing temperature and strength is shown in Figure 4. As a fairy tale, the strength increases as the curing temperature increases, but when the curing temperature increases to 90°C or higher, the strength decreases, and at 100°C, it drops sharply.

The sample cured at a temperature of 10 G'C had fine cracks, and it is estimated that the strength decreased due to these cracks. Therefore, the curing temperature is preferably 90°C or lower.

On the other hand, the lower the curing temperature, the lower the strength, and below 10℃, the development of hydraulic properties of Shichimen F is delayed.

In this case, unlike the case where the temperature is 100°C or higher, there is no problem if the curing is carried out for a long time. However, from the viewpoint of productivity etc., it is desirable to shorten the curing time as much as possible, and the lower limit of the curing temperature is also determined by the size of the equipment. A temperature of 20°C, which is about the same as room temperature, is suitable.

Further, Fig. 5 shows the results of investigating changes in strength O over time in saturated steam at a curing temperature of 20 to 90°C and in the atmosphere.

As is clear from Figure 6, there is no big difference in the rotational strength index over time in the temperature range of 20 to 90°C, and after 2 hours of curing, the rotational strength index is around 40). It has the same strength as uncalcined agglomerated ore, and it is judged that it will not cause an extreme decrease in yield or quality even if it is handled normally.

The atmosphere during curing does not necessarily have to be 4-saturated steam as long as the moisture in the uncalcined agglomerated ore is difficult to evaporate, and preferably the humidity is 80 to 90% or more.

Based on the above findings, in this invention, the saturated steam Nakajima pipe at a temperature of 20 to 90'C is heated to room temperature without applying any external force such as impact force or pressurization force that causes cracks or destruction to the lumps immediately after IJ. It is sufficient to cure and harden in the atmosphere for at least 2 hours, and then to cure, dry, and crush under known conditions until a predetermined strength is obtained.

In the method of the present invention, as a method for curing the lump after molding 11 without applying any external force such as impact force or pressurizing force that causes cracks or destruction, for example, the bottom plate and side frame of the molding frame can be cured. There is a method in which the parts are separated from each other, pressure molded on a roller conveyor, and after molding, only the side frame is removed, the bottom plate is attached, and the material is slid on the roller bomber until it reaches the platform, and then the product is cured on top of that. ' As mentioned above, the ζO invention applies impact force to the lump immediately after molding.
It is a non-fired agglomerated ore that grows long in the absence of external forces such as pressurizing force and at a temperature that provides a specified strength, so if external forces such as impact force or pressurizing force are applied immediately after forming, it is likely to crack or break. Even if there is a high yield and stable quality, it is possible to obtain products with high yield and stable quality.

Examples of the present invention will be described below.

〔Example〕

s1 The raw materials having the composition shown in Table 1 and the particle size structure shown in Table 2 are mixed, and 50 pieces of 1 to 10 pieces are included, and medium 1 is mixed.
It is molded into a block with the size of 50cm x length 4QQss x thickness Zoom, and this is cracked by impact force, pressing force, etc.

After being placed in a molding frame that does not apply external forces that may cause destruction and curing under various conditions such as room temperature air at a temperature of 20 to 90 degrees Celsius, saturated steam, etc., it is crushed (wAK) Maximum particle size: 501
The strength and yield p of 9 cold bond ore crushed to 11
Shown in the table. For comparison, Table 3 also shows the strength and yield of cold-bonded knitting, which is obtained by handling and curing a lump after molding.

From Table 3, it is clear that according to the method of the present invention, high quality products can be obtained with a yield of 70 or more.

Table 1 Composition of raw materials used [ " Table 2 Particle size composition of raw materials used ) , 11 spears 1

[Brief explanation of the drawing]

Figure 1 is a chart showing the relationship between the proportion of ore grains larger than lss and the degree of shrinkage in this invention; (Figure 4 is a chart showing the relationship between the rotational strength index and crushing yield of non-calcined agglomerated ore in this invention. Figure 4 is a chart showing the relationship between the curing temperature and rotational strength index in the same as above. Figure 6 is a chart showing the relationship between the rotational strength index in the same as above.) This is a chart showing the relationship between the rotational strength index and the rotational strength index.Applicant: Agent Sumitomo Metal Industries, Ltd. H1

Claims (1)

[Claims] The particle size is. , Hereinafter, □, , To the iron ore containing 10 to 8 degrees of the above, add pine paste and water if necessary, and if necessary, add one or two of the substances containing oxides such as solid reducing agent e C60e S 1oss MgO etc. In the method of producing unfired agglomerated ore by adding seeds or more and curing and hardening after shaping, the agglomerate immediately after forming is subjected to impact force, pressurizing force, etc. Temperature 20-9 without applying any external force that may cause damage
A method for producing uncalcined agglomerate ore, which is characterized by curing and hardening in saturated steam at 0°C or in the atmosphere at room temperature for at least 2 hours.