JPH0250921A - Method for operating sintering apparatus - Google Patents

Abstract

PURPOSE:To utilize the excess heat of a sintered cake and to increase yield by forming a grate protecting bed having a prescribed thickness between the grate of a sintering apparatus and ore to be sintered with ore having a prescribed small diameter as the lower limit of diameter collected from ore as raw material. CONSTITUTION:Ore having 2-5mm diameter as the lower limit of diameter is collected from ore as raw material including return ore and unsintered iron ore. A grate protecting bed is formed between the grate of a sintering apparatus and ore to be sintered with the collected ore and the thickness of the bed is regulated to 20-70mm. The dropping of raw material is prevented without considerably reducing gas permeability, the excess heat of a sintered cake is utilized and yield is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a method of operating a sintering machine, and more specifically, to a method of collecting and using bedding ore.

(b) Prior Art First, a typical method for extracting bedding ore in a conventional sintering machine and its usage will be explained. The sintered cake discharged from the sintering machine is crushed by a crusher and then classified into products, return ore, and bedding ore.

Figure 1 shows the details of classification. Generally 15mm for sieving
and sieves A and B with openings of around 5 mm are used. Return ore of less than 5 mm is used as return ore, and that of 5 mm or more is used as products. Bed ore is extracted from the part of the product that has a slightly smaller particle size. In this case, the particle size (hereinafter sometimes referred to as F size)
Those around 5 to 15 mm become bedding ore. Even when bedding ore is extracted from iron ore on a separate line, the same size is extracted.

The bedding ore collected in this manner is transported onto the grate of the sintering machine 1 before the raw material is charged, and is piled up to a thickness of several centimeters.

The function of the bedding ore is to prevent the raw material from falling through the gaps between the grate and to prevent the sintered cake from sticking to the gray h, thereby facilitating the ore discharge.

In other words, the gap between the crates is normally about 5 mm, and if raw materials are charged directly onto this, some of the raw materials are considerably smaller than 5 mm, so the amount that falls through the gap can be ignored. do not have. Therefore, the gap between the gray 1 and the raw material is appropriately closed, and a packed layer of bedding ore is provided between the gray 1 and the raw material to prevent the raw material from falling.

Furthermore, even if the falling of raw materials is negligible, without the intervening bedding layer, the grate will come into direct contact with the sintered cake whose maximum temperature exceeds 1300°C, resulting in thermal shock. The service life of the grate may be significantly shortened, or the grate and cake may seize, preventing smooth ore discharge. Therefore, a bedding layer is provided between the cake and the crete to absorb excess heat from the cake, protect the grate, and prevent seizing.

Considering the latter anti-seize function, the bedding ore takes over the thermal load from the sintered cake to the grate. In other words, bedding ore absorbs a considerable amount of heat, and attempts have been made to effectively utilize this surplus heat. For example, Tokuko Sho 53-3408
There is a method of forming a layer of return ore on bedding ore, charging raw materials thereon, and sintering, as in No. 2 and JP-A No. 58-61240. In this method, the surplus heat is absorbed into the return ore layer, and the return ore is sintered and agglomerated using the heat, thereby improving the yield.

However, in this method, equipment costs are higher than usual because it is necessary to add a return ore charging device and a return ore transport line to the ore supply section in order to form a return ore layer. That soil,
The particle size of the return ore is small, with an average particle size of about 2 cocoons, about 1 m.
Since it also contains a lot of powder with a diameter of less than m, the layer has poor air permeability. As a result, a decrease in production rate occurs. In order to avoid this, if the return ore layer is made thinner, the amount of agglomerated ore is also reduced accordingly, resulting in problems such as a decrease in the utilization rate of surplus heat.

(c) Problems to be Solved by the Invention The problems to be solved by the present invention are to create a sintering machine that can improve the yield by effectively utilizing the surplus heat of the sintered cake while minimizing equipment modification. The goal is to provide a method of operation.

(d) Means for Solving the Problems In the present invention, in the operation of a sintering machine in which a bedding layer is provided between the crate of the sintering machine and the sintering ore, grain size of 2 to 5 mm is obtained from the raw ore. The above-mentioned problem has been solved by collecting ore with a lower limit of .

Note that the raw material ore includes the above-mentioned return ore and unsintered raw iron ore.

(P) Function The operating method of the sintering machine of the present invention is such that when extracting bedding ore, the lower limit size thereof is from 2 mm to 5 mm, and using this bedding ore, a bed of layer Jl: 20 to 70 rnm is formed. Set the bedding layer.

In the present invention, bed ore is collected with a smaller F limit size than before, and by using this with an appropriate layer thickness, excess heat is used to agglomerate the part that did not become a product, improving the yield. do. When the lower limit size is made smaller, for example, as shown in FIG. 1, the coarse grain portion of the portion that has not become return ore is mixed with conventional bedding ore and collected. Since this coarse grain portion is close in size to the product, it has the potential to be sintered into a product even with a small amount of heat. Therefore, it is ideal for utilizing surplus heat. When this coarse grain part mixes with the bedding ore of conventional size and receives surplus heat from the cake, the coarse grains sinter together. As the process progresses, it grows to the size of the product. Since this agglomeration is performed using surplus heat, agglomeration is performed without the addition of fuel, which improves the yield.

Furthermore, regarding the air permeability of the bedding layer, since only the coarse part of the return ore is used and it is mixed with the bedding ore of conventional size, the reduction in air permeability is almost ignored.

Considering the layer thickness, if the layer thickness is small, that is, if the amount of bedding is small, excess heat cannot be fully utilized. Furthermore, if the amount is too high, the excess heat may be used without wastage or the thickness of the raw material layer will become small, so there is an appropriate value for the layer thickness of the bedding. In terms of equipment, only changing the mesh size of sieve B does not require any other additional equipment. The details of the lower limit size and appropriate values for the bedding layer thickness will be explained below.

The smaller the minimum size of the bedding ore, the more the portion that was conventionally used as return ore will be recovered as bedding ore. However,
If too small a return ore is put into the bedding ore, the amount of bedding falling from the grate will increase, and the permeability of the bedding layer will deteriorate as in the conventional method.

Figure 2 shows the results of investigating the relationship between the lower limit size of bedding ore, falling amount of bedding, and air permeability. There is almost no difference compared to the bedding, which is about 5 mm in size, so there is no problem. Regarding the amount of fallen bedding, it increases as the minimum size decreases. This increase is also small and does not cause any particular problem. However, if the lower limit size is set to about 2 mm or more in consideration of air permeability, there will be no problems in actual operation such as a decrease in production rate.

Next, Figure 3 shows the results of an investigation into the appropriate thickness of the bedding layer. Here, according to the pot test, the raw material layer thickness is 500
Investigate the yield improvement effect by changing the bedding N thickness while keeping the rnm constant. The yield improvement effect increases as the bedding layer thickness increases, but regardless of the lower limit size, when the bedding layer thickness is 7
F,) As long as it is about mm or more, the effect is fine! You can see that it is close to that.

At the same time, when the diameter was less than 20 mm, the phenomenon of burning in the crate was frequently observed. Therefore, it can be said that the appropriate bedding layer thickness is in the range of about 20 to 70 mm.

(F) EXAMPLE Investigate the effect on yield by using bedding ore with a smaller minimum size under each operating condition shown in Table 1 in a sintering machine with an effective area of 500 d. The upper limit for collecting bedding ore has been set at 15 mm, the same as before, and the lower limit size and bedding layer thickness have been changed. The lower limit size was conventionally 51 mm, but the opening of sieve B in Figure 1 was gradually reduced to 4°3.2 mm. There were two types of bedding layer thickness: 20 mm and 7 On+m, each with a test thickness of 1-1. The firing load and raw material layer thickness were kept the same as in the conventional method.

Part 1 table The yield of particles with a particle size of 5 mm or more is summarized in FIG.

When the lower limit size is reduced to 2 mm, the bedding layer thickness is 70 mm.
mm, a yield direction -L of about 7% was observed compared to the conventional method. Even in the case of the lower limit size or 4 cylinders, there was an improvement of 1 to 2%. In either case, the firing time was not extended and there were no other problems.

Note that, although not shown in the examples, the same yield improvement effect can be obtained even if the method of the present invention is applied to iron ore before sintering.

(F) Effect According to the present invention, the coarse grained portion of what was conventionally used as return ore enters the bedding ore, and this coarse grained portion absorbs the excess heat of the sintered cake and agglomerates it. , yield is improved. In addition, compared to the conventional method of using surplus heat, there is no need to add new hoppers, transportation lines, etc., and it is only necessary to change the mesh size of a specific sieve, which reduces sintering costs. can.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of typical bedding ore extraction to which the method of the present invention is applied. Figure 2 is a graph showing the influence of the minimum bedding ore size on bedding layer permeability and amount of fall from the grate. Figure 3 is a graph showing the relationship between bedding layer thickness and yield improvement effect. FIG. 4 is a graph showing the effects of the embodiment of the present invention.

Claims (1)

[Claims] In the operation of a sintering machine in which a bedding layer is provided between the grate of the sintering machine and the ore for sintering, ore with a particle size of 2 to 5 mm as the minimum is collected from the raw ore, and this ore is used to form a bedding layer with a particle size of 20 to 5 mm. 7
A method of operating a sintering machine characterized by forming a bedding layer of 0 mm.