JPH01184236A - Production of mgo-containing sintered ore - Google Patents

Abstract

PURPOSE:To produce a sintered ore which is uniformly dispersed with MgO and has high strength by using MgO-contg. raw materials such as serpentine and dolomite as a bedding material on a sintering pallet and depositing ordinary sintering raw materials thereon, then sintering the materials from above to below at the time of producing the MgO-contg. sintered ore. CONSTITUTION:The grains, sized 7-30mm, of the MgO-contg. raw materials such as serpentine or green dolomite are used as the bedding material on the endless pallet of a sintering machine and the sintered ore raw materials consisting of powders of iron ore and coke, etc., are deposited thereon, then the upper part is ignited to sinter the coke in the raw materials from the upper part to the lower part in order to produce the molten ore contg. MgO and having a low S content by forming basic slag in a blast furnace as the sintered ore for the blast furnace. The MgO-contg. bedding material are calcined and the part thereof is half fusion-bonded with the sintered ore by the sintering reaction heat of the middle and lower layers in the sintering raw materials. Such sintered raw ore is disintegrated and the high-basicity sintered ore into which the MgO is uniformly incorporated is obtd.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for producing sintered ore used in a blast furnace.

(Prior art) Generally, when producing pig iron by reducing iron ore in a blast furnace, a method is adopted in which MgO-containing materials such as serpentine or dolomite are directly added to increase basicity and reduce S in the pig iron. has been done.

However, in this method, since the amount of addition needed to adjust the basicity is small, it is extremely difficult to distribute it evenly in the furnace, resulting in reaction inhibition or poor furnace conditions. Also,
Increasing the amount added to prevent this reaction inhibition will result in an increase in the amount of slag produced by the reaction and an increase in the amount of heat supplied.
This will result in a deterioration of the iron production ratio or unit heat consumption, or poor furnace conditions.

In order to improve these drawbacks, various methods have been proposed in the past, and one typical method is to add MgO materials such as serpentine, dolomite, Ni slag, etc. to the sintering raw material and perform sintering. A method has been proposed, such as Tetsu-to-Hagane, 8O-842, which can be expected to improve the bending.

(Problem to be solved by the invention) However, when using the above-mentioned MgO-containing material as a sintering raw material,
．． When 0% is added and sintered, this MgO has a high melting point, so if the particle size is 0.25 to 0.5 mm or more, only the outer periphery of the particle undergoes a melting reaction, resulting in extremely poor reactivity.

This is clear from the fact that the diffusion state of the Mg element in the melting reaction zone is about 70μ when dolomite is added as an example. Therefore, when these MgO-containing sintering raw materials are sintered, the strength of the product decreases due to poor sintering, and the yield of the product also deteriorates.
It increases as the amount of gO added increases.

Furthermore, due to its high melting point, in order to perform sufficient sintering, it is necessary to increase the amount of fuel such as coke or oil mixed into the sintering raw material, leading to an increase in the fuel consumption rate.

In this way, using MgO-containing materials for sintering improves the quality of the finished product.
This leads to deterioration in yield, production efficiency, fuel consumption, etc.
Obtaining MgO-containing sintered ore involves major technical challenges.

Therefore, the present invention provides an effective method for producing MgO-containing sintered ore that solves the above-mentioned technical problems in the production of MgO-containing sintered ore, and also aims to improve blast furnace reaction efficiency and stabilize operation.

(Means for Solving Problem A) The present invention provides a continuous sintering method in which sintering raw materials and sintering fuel are charged into a sintering pallet and sintered by burning from above. The method is characterized in that one type of serpentinite or raw dolomite or a mixture thereof is laid on the bed, and the sintering raw materials are charged onto the bed and sintered sequentially from above, and then the materials are crushed and classified. This is a method for producing MgO-containing sintered ore.

(Function) The present inventors have found that all the problems can be solved by dividing and firing the layers using a sintering pallet, and then mixing the divided layers to form MgO-containing sintered ore.

The present invention uses a downward suction sintering machine to create a bed of sintered pallets with MgO-containing serpentinite or green dolomite.
The seeds or their mixture are charged in the appropriate layer thickness. At this time, the layer thickness is set to such an extent that the conventional bedding function is not impaired, and the size of the serpentine and raw dolomite is 7 to 30 mm. Next, commonly used sintering raw materials such as iron ore and coke are charged onto this MgO-containing bed, and ignited from above to sequentially sinter downward. Through this reaction, each of the sintering raw materials is sintered independently, and the bedding part is fired at Ototemperature due to the heat of the sintering reaction in the middle and lower layers, and a part of it is semi-fused with the sintered ore, forming the sintered ore. Integrate by firmly welding. Thereafter, by crushing and classifying the sintered ore, MgO-containing sintered ore is obtained in which the fired part of the single MgO-containing material and the MgO-containing material semi-fused with the sintered ore are uniformly dispersed.

By charging this MgO-containing sintered ore into a blast furnace, the dispersibility in the furnace is greatly improved and a uniform concentration can be maintained. As this can be promoted, refining efficiency and operational stability can be greatly improved. In addition, since the MgO-containing sintered ore produced by the method of the present invention does not directly sinter the MgO-containing material by adding it to the sintering raw material, the strength of the sintered ore may decrease due to poor sintering of the MgO-containing material. In addition, there is no need to make the particles fine to promote the reaction of the MgO-containing material, and therefore, there is no obstruction of ventilation, and there is no problem with the sintering operation. Moreover, since this MgO-containing material is used as a bedding, there is no need for the conventional bedding of sintered ore, which is extremely advantageous in terms of yield, thermal efficiency, productivity, etc.

The particle size of the MgO-containing material used as the bedding here is 7-30.
ffff1. Preferably, it is 10-20+m111, but if the bedding material is smaller than 71, the falling from the grate will increase, a stable bedding layer will not be formed, and there will be poor ventilation due to clogging between the grate, The bedding loses its original meaning. Moreover, if it is larger than 30 mm, there are problems such as mixing of raw materials into the bedding material, making it impossible to form a stable bedding layer, and causing cracks due to thermal strain. For these reasons, by setting the thickness to 7 to 30 mm, preferably 10 to 20 mm, both the ventilation as a bedding and the contradictory bedding effects can be sufficiently satisfied, and the semi-fusion rate and dispersion into the sintered ore can be improved. Most stable. Further, by using either serpentinite or raw dolomite or a mixed combination as the MgO-containing source, it becomes easy to produce low-SiO□ sintered ore, and the quality of the sintered ore is improved.

(Example) The manufacturing method of the present invention was applied to an actual machine, and serpentinite 10 to 201 as the M and O material was placed on a sintered pallet 7) as a bedding.
The sintering material was charged so as to have a layer thickness of 0IIIO, and a normal sintering raw material mixed with coke and others was charged onto this bedding and sintering was performed. The results are shown in Table 1 in comparison with a conventional example in which MgO content was directly added to sintered ore, and it is clear that the method of the present invention is approximately 2% higher in both strength and yield, demonstrating an improvement effect. Recognize.

In addition, each of these sintered ores is charged into a blast furnace and MgO
As a result of comparing the dispersibility of steel, blast furnace operability, etc., there was almost no difference in dispersibility, but the method of the present invention was superior in both desulfurization and operational stability, as shown in the hot metal S value shown in Figure 1 as a representative characteristic. .

Table 1 (Effects of the Invention) As described above, the method for producing MgO-containing sintered ore of the present invention makes it possible to maintain good yield, fuel consumption, etc. without impairing the strength of the sintered ore product, and Dispersion uniformity and operational stability during blast furnace charging are extremely improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the S value in hot metal when MgO-containing sintered ores according to Examples and Conventional Examples are charged into a blast furnace.

Claims (1)

[Claims] (1) In the continuous sintering method in which sintering raw materials and sintering fuel are charged into a sintering pallet and sintered by burning from above, one or more types of serpentinite or green dolomite with a size of 7 to 30 mm are used. A method for producing MgO-containing sintered ore, which comprises laying a bed of a mixture of the above, charging sintering raw materials onto the bed, sequentially sintering them from above, and then crushing and classifying them.