JPS593511B2 - Method for producing small pellets using fine coke - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing small pellets using fine coke, particularly fine coke having a particle size of 149 μm or less.

The coke charged into the blast furnace at a steelworks is carefully controlled in terms of its pulverizability, cold and hot strength, and harmful components such as sulfur content, as well as to ensure a certain level of air permeability within the blast furnace. Particle size control of charged coke is strictly controlled along with particle size control of other charged raw materials.

The coke charged into the blast furnace is generally 75 m long if it is large.
Depending on the operating conditions of the blast furnace, the grain size is arbitrarily selected from a particle size of 1571t7IL to a small particle size of 1571t7IL, and the particles are sized by crushing and sieving.

These fine particles unsuitable for blast furnace charging, which are generated during the sizing of coke charged into the blast furnace, are further crushed and adjusted to a particle size suitable for use as fuel for sintering powdered iron source raw materials such as powdered iron ore. Ru.

In general, fuel coke for sintering is considered to have a diameter in the range of 1 to 3 mm. For example, relatively coarse powder coke with a particle size of more than 3 or 5 mm will cause thermal distribution to be uneven in the sintered layer. On the other hand, if the grain size is small, e.g. 0.2
Fine coke particles with a diameter of 5 mm or less impede air permeability in the sintering raw material charging layer and deteriorate sintering efficiency, so these fine coke particles are not preferred.

Therefore, fine coke powder, which is not suitable as a fuel for sintering, is used not only during the sizing of coke charged in the blast furnace and during sizing of coke for sintering, but also during handling such as coke manufacturing or coke transportation. occurs in large quantities.

Although these fine coke particles are collected by dust collection equipment, they are not used as fuel for sintering, let alone in blast furnaces, and are often stored in yards, etc., but some of them are converted into charcoal or briquettes. used as raw material.

However, although it is desired that these fine coke powder be used effectively in steel plants as a useful fuel, it is not possible to do so because they have sharp protrusions on the particle surface and are porous and have no caking property. It is extremely difficult to roll and granulate iron ore powder, etc., and it is often compressed into briquettes or pulverized charcoal in a mold with the addition of a binder.

The present inventors have conducted various studies on granulation methods for forming fine coke powder, which has poor granulation properties and has not yet been effectively utilized, into particles suitable for use, for example, as sintering fuel. The present invention has been completed and will be described in detail below.

That is, in the granulation of fine coke powder of the present invention, prior to transfer granulation, the fine coke powder is kneaded with cement in a rotary dish that is equipped with a high-speed rotary blade and rotates at a low speed in the opposite direction to the high-speed rotary blade. The method is characterized by carrying out a preliminary treatment to form bonded granulation nuclei through collision and bonding of fine coke particles during the kneading process.

As mentioned above, the coke powder used in the granulation of the present invention is mainly composed of fine powder with a particle size of 149 μm or less, which is generated in coke manufacturing or during sizing as coke for blast furnaces or sintered fuel. This is fine powder coke as illustrated.

Since the above-mentioned fine coke powder has almost no caking property, it can hardly be granulated by transfer granulation alone.Therefore, prior to transfer granulation, pretreatment specified by the present invention is required. shall be.

In other words, cement is added as a binder to coke powder, which is mainly composed of fine powder with a particle size of 149 μm or less, and water is added to control the humidity to adjust the raw material to a state suitable for the formation of fine transferred granulation nuclei. .

In the above raw material preparation of the present invention, the amount of cement added to the fine coke powder is 7% based on the dry weight of the fine coke particles.
A range of 19 to 19 is preferable; below the lower limit, the amount added is too small to obtain the necessary consolidation strength, while above the upper limit, it is uneconomical and the fuel components are diluted.

In addition, it is preferable to control the humidity of the raw material so that the moisture content is within the range of 20 to 30 parts, and the larger the particle size distribution of the fine coke powder or the larger the amount of cement mixed, the larger the amount added should be within the above range. It is.

In addition, the cement added as a binder in the present invention is
Although not particularly limited, Al2O3Mgo causes a decrease in sintering productivity when used as a sintering fuel.
It is recommended to use ordinary Portland cement or early-strengthening cement, which has a relatively low content.

The fine coke powder thus prepared is then placed into a rotating plate which has a high-speed rotating blade eccentrically inside and is rotated at a low speed in a direction opposite to that of the high-speed rotating blade.

The rotating plate is rotated together with the input fine coke at a relatively low speed, for example, 25 to 80 rpm, but within the rotating plate, the rotating plate rotates at a speed of 350 to 1,500 rpm in the opposite direction to the rotating plate.
The rotor blades, which rotate at a relatively high speed such as rpm, compress the fine coke in the rotary dish with a strong impact, and also move in the opposite direction to the direction of rotation of the dish to push it back and agitate it.

In such a compression and agitation device with mutually opposite rotational directions and high-speed rotary blades, the fine coke particles are compressed by the high-speed rotary blades, and the fine coke particles are strongly pressed against each other to form a surface area of the particles. The sharp protrusions and the recessed holes are intertwined with each other to form a physical bond between the particles, and the bond is assisted by the cement, thereby forming a granulation nucleus.

These granulation nuclei undergo grain growth due to the polling effect due to transfer in the rotating plate, and peracid long grains due to the rotary blade, for example, particle size 3.
The peracid long grains with a diameter of 1 to 3 mm are finely divided by shearing.
mm granulation nuclei are formed.

The granulation core particles pre-granulated in this way are then charged and transferred together with fine coke into a transfer granulation device such as a polling disk or a polling drum, whereby the formed powder is consolidated and further grown. , spheroidized and granulated to a desired size.

This granulated material is cured in a curing field for several days to solidify the blended cement.

The method for granulating fine coke of the present invention is as described above, and examples will be further described below.

Figure 2 shows an example of a flowchart for granulation of fine coke of the present invention, in which fine particles with a particle size of 149 μm or less are sieved through a sieve containing a ratio of 68.3 as illustrated in Table 1. Ordinary portland cement 8 as a binder for dust coke
A high-speed rotary blade 2 with a rotation speed in the range of 350 to 1500 rpm is installed eccentrically inside the high-speed rotary blade 2.
When the raw material in the rotating plate 1 is fed into a rotating plate 1 that rotates at a low speed in the range of 25 to 80 rpm in the opposite direction to the rotating direction of At an eccentric position in the dish 1, the particles are captured by the rotary blades 2 rotating at high speed in the opposite direction, and the particles are impulsively pressed together and bonded to form granulation nuclei, while peracid long grains with a particle size of 3 mrIL or more are caught in the eccentric position. The particles were compressed or atomized by the impact of the installed high-speed rotary blades, and granulation nuclei with a particle size of 1 to 3 mm were generated.

The produced granules also contain some fine powder with a particle size of 0.5 mm or less, and these are supplied to a dish-shaped rolling granulator 4 via a quantitative feeder 3.

In the granulator 4, the charged material is transferred to the granulation cores as granulation growth nuclei, fine coke particles are attached and grown, or the granulation cores are contacted and bonded, and further compacted and spheroidized for a residence time of 2. In ~5 minutes, the particle size is as large as 4-5 mm, and as small as 0.5-5 mm.
Granulated into mini cold pellets of LOmm.

The particle size distribution of the mini-cold pellets thus granulated is mostly 1 to 2.2 m1t, as shown by line B in Figure 1.
It was possible to obtain an extremely stable granulation agglomeration, which was compacted and had a grain size of t.

Curve A in FIG. 1 shows the production distribution of granulation nuclei of various particle sizes obtained in preliminary granulation, but concentrated formation of granulation nuclei of a specific particle size cannot be obtained.

The mini-cold pellets granulated as described above were charged into the primary curing tank so that the layer thickness was 1 m, and after temporary curing for 2 days, the mini-cold pellets that had coagulated and solidified with each other were rotated. The pellets were supplied to a drum-type crusher 6 and crushed, and the crushed pellets were further supplied to a secondary curing tank 7 for curing for 6 days.

In the present invention, the curing step does not necessarily require a crushing step, and the crushing step can be omitted by selecting a curing method that does not cause coagulation and solidification between particles, such as by reducing the layer thickness during curing.

The mini-cold pellets thus obtained were used as fuel for sintering fine iron ore, and very good sintering productivity could be obtained.

The method for granulating fine coke of the present invention is as described above, and involves cold processing of fine coke powder, which is generated in large quantities in coke manufacturing plants, coke sizing plants, coke handling, etc., and using a press molding machine. It is possible to produce coke mini-cold pellets that can be used in practical applications, such as coke powder for sintered fuel, without using it, opening the way to the economical and effective use of fine coke powder, which has been difficult to dispose of. Ta.

[Brief explanation of the drawing]

FIG. 1 is a particle size distribution diagram of preliminary granulation and rolling granulation according to the production method of the present invention, and FIG. 2 is a granulation process diagram showing an example of the implementation of the present invention. A... Pre-granulation degree distribution curve, B...
Rolling granulation particle size distribution curve, 1...Rotating plate, 2...
...Rotary blade, 4...Dish type rolling granulator, 5.
...Primary curing tank, 6...Crusher, 7...
...Secondary curing tank.

Claims (1)

[Claims] 1. A raw material conditioning step in which cement is blended with fine coke powder with a particle size of 149 μm or less and water is added to adjust the humidity, and a high-speed rotating stirring blade is installed eccentrically inside the adjusted raw material powder, and the stirring blade is in the opposite direction. A preliminary granulation step in which the combined granulation cores with a particle size of 3 mm or less are formed by placing them in a rotary dish that rotates at a low speed, and then the combined granulation nuclei are transferred together with fine powder in a transfer granulation machine. A method for producing small pellets using fine coke, which comprises a granulation process and a curing process for curing the granules.