JPS6233537A - Molten slag pelletizer - Google Patents

Abstract

PURPOSE:To improve pelletization efficiency and to recover the sensible heat of slag by designing agitating vanes for transferring molten slag while agitating and cooling the same so as to have the lead angle which is stepwise or continuously increased toward the transfer direction. CONSTITUTION:The agitating vanes in the 1st stage of the melting section are constituted to have the small pitch P1 and lead angle theta1 and a large number of vanes. The molten slag is slowly transferred toward the direction of a pelletized slag discharge port 23 while the slag is kept agitated. The sensible heat of the molten slag is recovered by the cooling medium flowing inside and outside during this time. The slag expands in volume to form large lumps at the outlet of the 1st stage. The agitating vanes are constituted to have the pitch P2 and lead angle theta2 larger than the 1st stage and the smaller number of vanes in the 2nd stage of the melting - half-solidifying section so that the expanded slag is moved without being stagnated in a casing 21 and the large lumpy slag is disintegrated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a molten slag granulation device that efficiently granulates molten slag and recovers sensible heat from the slab.

[Conventional technology]

As an apparatus for granulating molten slag while stirring and cooling it, for example, there is an apparatus disclosed in Japanese Utility Model Application Publication No. 57-90735. As shown in FIGS. 6 and 7, this apparatus is equipped with a semi-cylindrical casing 1 and a transfer rotary body 5 inside the casing 1, which granulates the molten slab while stirring and cooling the molten slab. The semi-cylindrical casing 1 has a molten slab supply port 2 at one end, a granulated slag discharge port 3 at the other end, and a cooling medium passage 4 on the outside. The transfer rotary body 5 extends from one end to the other end in the casing 1, has stirring blades 6 arranged in a spiral shape around the outer periphery, and has a cooling medium passage 7 inside.

The stirring blade 6 is used exclusively for stirring and transporting the molten slag, and there are two cases in which one blade is arranged in a continuous spiral as shown in FIG. In some cases, a large number of blades are planted and arranged in a spiral pattern. In either case, the pitch and lead angle of the stirring blades 6 are constant throughout, regardless of the state of the molten slag being stirred, cooled, and transferred, that is, the state of melting and solidification. Therefore, the molten slag supplied from the molten slag supply port 2 is granulated while being stirred and cooled at a constant pitch and at a constant lead angle, and is transferred to the granulated slag discharge port 3 provided at the other end of the casing 1.

[Problem that the invention seeks to solve]

By the way, in blast furnaces of 3,000 to 5,000 m' class, the amount of slag generated is several tons/m at its peak.
Reach 1 n or more. In order to continuously stir and granulate the molten slag even at peak times, it is necessary to efficiently cool it and to transport and discharge it. However, conventional apparatuses have a problem in that when the throughput exceeds a certain level, the cooling function or the conveying/discharging function is insufficient, and the processing cannot be performed any further.

For example, the rotation radius of the stirring blade is 600ffi+11,
For equipment arranged with a lead angle of 20°, the throughput is 50°.
0kg/min is the limit, 800-1000 kg/m
If it becomes in, slabs will accumulate in the coagulation section and the conveyance function will be lost.

Moreover, at 800 to 1000 kl/min, the cooling function is insufficient and a satisfactory granulation process cannot be performed.

When the present inventor investigated the cause, it was found that the low throughput was due to the pitch and lead angle of the stirring blade.

Therefore, the present invention provides a molten slag granulation device that efficiently granulates molten slag and recovers the sensible heat of the slag by changing the grip and lead angle of the stirring blade according to the melting/solidification state of the slag. The purpose is to

[Technical means to solve the problem] In order to achieve the above object, the present invention provides a casing having a molten slag supply port at one end, a granulated slag discharge port at the other end, and a cooling medium passage on the outside. In a molten slag granulation device, the molten slag granulator is equipped with a stirring blade that stirs, cools, and transports the molten slab from one end of the casing to the other end, and is equipped with a transfer rotor having a cooling medium passage; The IJ angle is increased stepwise or continuously in the transport direction.

The true specific gravity of molten slag is approximately 2.5, and when it is solidified and granulated,
``The bulk specific gravity is approximately 1.5, and the volume increases by approximately 1.7 times during the melting/solidification granulation process.Therefore, if the lead angle of the stirring blade is kept constant as in the past, the volume expansion causes the conveyance to increase by a factor of 1.7. If the discharge function is reduced and the transfer rotor is rotated faster to increase this capacity, the cooling function will be reduced and a satisfactory granulation process will not be possible, resulting in a limit to processing capacity. Breaking through this limit. It is necessary to change the transfer speed according to the melting and solidification process of the slag.Since the volume of the slag expands during the process of melting and solidifying, the lead angle of the stirring blade should be increased to match the increase in the volume of the slag. It is necessary.

Furthermore, when increasing the processing capacity, the rotational speed of the transfer rotary body is increased, and the stirring/cooling period is generally shortened. Therefore, in order to ensure a sufficient cooling period, it is desirable to set the pitch of the stirring port blades to be small near the molten slab supply capacity and to be large near the granulated slag discharge port. The efficiency is highest when the ratio of the lead angle near the granulated slag discharge port to the lead angle near the molten slag supply port is set in accordance with the volume increase rate of the slag. As mentioned above, the volume increase rate of the slab is about 1.7, but the value changes depending on the addition of coolant etc. or the slag composition.
It ranges from about 1.2 to 3. Therefore, the above ratio is 1.2~
It is desirable to set it to 3. A stirring blade having such a pitch and lead angle can be constructed by winding a single plate in a spiral shape, or it can be constructed as an aggregate of small pieces of stirring blades in a substantially spiral shape, or by spirally winding a single plate. In the case of the latter, the stirring capacity is excellent, and since the number of stirring blades can be changed for each stage, the throughput can be further increased.

[Effect]

Since the lead angle of the stirring blade gradually or continuously increases in accordance with the volume increase of the slag, the molten slag advances slowly near the molten slag supply port, and after being stirred and cooled, it gradually or continuously increases in accordance with the volume expansion. The granulated slag moves quickly towards the granulated slag discharge port.

In addition, the cooling capacity can be balanced with the conveying capacity by increasing the pitch according to the lead angle, so even if the transfer rotor is rotated quickly to increase processing capacity, the cooling capacity and conveying capacity will be extremely low. It never declines.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. The embodiment shown in FIGS. 1 to 5 is the best embodiment of the present invention, and the stirring blades are structured in steps from the molten slag supply port to the granulated slag discharge port. To explain sequentially according to the figures, the casing 21 has a semi-cylindrical cross section,
A molten slag supply port 22 is provided at one end, and a granulated slag discharge port 23 is provided at the other end. The granulated slag discharge port 23 is constructed by opening the other end of the casing 21. Although not shown on the outside of the casing 21, a cooling medium passage is arranged.

Inside the casing 21 is a transfer rotary body 2 extending in the longitudinal direction.
4 is rotatably supported by bearings 25 at both ends. The center of the transfer rotating body 24 is hollow and the cooling medium passage 2
6, and a large number of stirring blades 27 are installed in steps around the outer periphery. The stirring blade 27 is configured in several stages depending on the state of the slag. In this example, there are three states of slag: molten, molten to semi-solid, and solidified granulation.
It is divided into stages, and the stirring blades 27 are configured in accordance with the stages. That is, the structure of the stirring blade 27 is a melting part, a melting part,
It is divided into three stages: a semi-solidified part and a solidified granulation part, and each stage consists of several stages. The pitch and lead angle of the stirring blades 27 are different for each stage, and increase from the melting section to the solidification and granulation section. That is, the respective pitches and lead angles in the molten part, molten to semi-solidified part, and solidified granulation part are Pl,
If θ1;P2, θ2;P31θ3, then Pi<P
2<P3, θ1 x θ2 x θ3. Further, in this embodiment, the number of stirring blades 27 constituting each stage is made different for each stage. In the first stage melting section, the main focus is on stirring and cooling, and the number of stirring blades 27 is set to six as shown in Figures 2 and 3. From the second stage onwards, the main focus is on granulation transfer and stirring. The number of blades is 270, and the number of blades is five as shown in FIGS. 4 and 5.

In addition, the illustration 28 is a sprocket, 29 is a chain, and 30
The zero-order action will be explained, where is a gutter and 31 is a molten slag.

In the first stage melting section, the pitch P1t lead angle θ of the stirring blades is small and the number of blades is large, so that while the molten slag is being stirred,
3, during which the sensible heat of the molten slag is recovered by the cooling medium flowing inside and outside. The slag expands in volume at the exit of the first stage and becomes a large lump. In the second stage of melting to semi-solidification, the stirring blade pitch P21')
- The expanded slag and casing 21 because the angle θ2'' is larger than the first stage and the number of blades is reduced.
It transfers without being retained in the interior and crushes large slabs. In the solidification section of the third stage, the pitch P3+'J- angle θ3 is set even larger, and the slag crushed in the second stage is further cooled and crushed while being granulated. Although the slab further expands in volume during the granulation process, pitch P3.
Since the IJ angle θ3 is set large, the slag does not stay in the casing and the granulated slag discharge port 23
It is discharged smoothly. Further, since the pitch P3 and the lead angle θ are formed coarser than those in the previous stage, excessive crushing of the slag is prevented.

〔Effect of the invention〕

According to the present invention, since the pitch and lead angle of the stirring blades are increased stepwise or continuously in the conveying direction, the conveying force increases in accordance with the volume expansion of the slag, eliminating slag retention and cooling. The area can be used effectively. Furthermore, compared to equipment of the same scale, the granulation processing capacity is increased by 2 to 3 times.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view taken along line AA in FIG. 1, and FIG. 3 is a sectional view taken along line BB in FIG. 1.
Figure 4 is a sectional view taken along line C-C in Figure 1, and Figure 5 is a cross-sectional view taken along line D-1 in Figure 1.
D sectional view, Fig. 6 is a vertical sectional view of the conventional device, and Fig. 7 is the 6th sectional view.
The cross-sectional views in the figure and FIGS. 8 to 10 are perspective views of the transfer rotating body used in the conventional apparatus. 21... Casing, 22... Molten slag supply port,
23... Granulated slag discharge port, 24... Transfer rotating body,
26... Cooling medium passage, 27... Stirring blade. Figure 6 Figure 10

Claims (2)

[Claims] (1) A casing that has a molten slag supply port at one end, a granulated slag discharge port at the other end, and a cooling medium passage on the outside, while stirring and cooling the molten slag from one end to the other end of the casing. , in a molten slag granulator equipped with a transfer rotor having a stirring blade for transport and a cooling medium passage; the lead angle of the stirring blade is increased stepwise or continuously in the transport direction; A molten slag granulation device characterized by: (2) In claim 1, the lead angle is such that the ratio S/M of the lead angle S near the granulated slag discharge port and the lead angle M near the molten slag supply port is 1.2 to 3. A molten slag granulation device characterized by having a lead angle such that: