JPS5848609A - Monitoring method for progressing condition of sintering - Google Patents

Abstract

PURPOSE:To control sintering speed adequately and to improve the hot reduction powdering index and cold strength of sintered ore in the stage of producing sintered ore with a Dwight-Loyd sintering machine by detecting the moisture in sintering raw materials by making use of neutrons. CONSTITUTION:Pallets 3 of a Dwight-Lloyd sintering machine are rotated by means of a sprocket 31. Bedding ore and moisture-controlled sintering raw materials are loaded onto the pallets from a bedding hopper 33 and a charging hopper 34 to a uniform thickness. The carbon materials in the sintering raw materials are ignited by an ignition furnace 35 and the heat is retained by a heat retaining furnace 36. Air is passed from the top to the bottom surfaces to sinter the raw materials. In this case, neutron moisture meters 2 consisting of neutron sources 21 in the lower parts of the pallets and neutron detectors 22 are disposed in the midway of the pallets 3. While the neutrons emitted from the sources 21 pass through the sintering raw material layers, the neutorons are converted to thermal neutrons according to the varying contents of the moisture contained in the raw materials; therefore the moisture in the sintering raw materials is detected precisely by measuring the transmittance of the neutrons through the sintering raw materials with the detectors 22, by which the sintering operations are controlled optimally.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for monitoring the progress of sintering of a raw material by detecting moisture in the raw material during firing using total neutrons.

The Dwight Lloyd sintering machine, which is widely used in general, drives a large number of pallets arranged in an endless manner, sequentially supplies sintering raw materials at the feed end, and ignites the surface of the pallets. The air is sucked in by the air collection box placed under the moving area of the pallet and blows through from the surface of the sintered raw material on the MLf pallet to the lower surface side, so that the firing progresses downward from the surface of the raw material, and the pallet The firing of the raw material is completed just before the sintered ore reaches the ore discharge end, and the sintered ore is sent out from the ore discharge end toward the primary cooling device.

If sintering is not completed before the pallet reaches the discharge end, the ore will be discharged from the pallet in an unsintered state, and the sintering process will be repeated again as return ore.
If the retention rate decreases, and if the sintering progresses too quickly, it tends to cause unevenness in the sintering, and not only does the amount of return ore increase, but also the amount of heat generated increases, making it easy to burn out the pallet.Therefore, the sintering process It is necessary to appropriately control the moving speed of the pallet, the negative pressure of the air collection box, etc., which affect the firing completion position, but as a prerequisite for this, it is necessary to accurately understand the sintering progress status. . Conventionally, the following methods have been used to monitor the progress of sintering. That is, in the sintered packing layer on the pallet -
Or, by inserting thermocouples at multiple locations, it is determined from the vertical and horizontal temperature distribution in the sintered packed bed that approximately 1 sintered raw material is in the combustion front in the sintered packed bed, that is, in the pallet movement direction.
A method of monitoring the sintering progress by estimating a line connecting points heated to 00°C, or a method of monitoring the combustion front or combustion zone based on the exhaust gas temperature, air volume, or gas analysis information from the air collecting box. A method has been proposed for detecting an area where the sintering raw material is heated to 1000° C. or higher and monitoring the progress of sintering.

However, all of the above-mentioned methods have drawbacks such as being difficult to carry out continuously on-line and the progress of sintering being difficult to grasp.

The present inventors conducted experiments and research on the relationship between the progression of combustion m-rays of the sintering raw material on a pallet and related factors, particularly moisture, and as a result, the following findings were obtained. In other words, sintering raw materials are generally supplied onto pallets with their moisture content adjusted to a constant level (approximately 5 to 7%), but when sintering is completed, the moisture content is approximately zero, and the In the process, changes occur as shown in Figures 1 (a) and (b). FIG. 1(a) is a schematic diagram showing the ignition of the sintered packed bed, that is, the firing progress from the start of firing to the completion of firing;
Figure 1 (cut) is a graph showing the distribution of moisture content in a vertical cross section of each part of the sintered packed layer, with the horizontal axis showing the moisture content and the vertical axis showing the position in the layer thickness direction. As is clear from the graph, assuming that the moisture content of the sintering raw material charged into the pallet is 5%, when firing starts, combustion zone B
1. In the completed firing zone C, the moisture content becomes almost zero, and on the other hand, some of the moisture vaporized in this area condenses during the process of passing through the unburned zone A by the wind blowing downward from the top surface of the sintered raw material. The moisture content in combustion zone A increases from 5% to about 8% (Fig. 1 (corresponding to position b in Fig. 1 (a))
→See graph). As firing progresses, the regions of combustion zone B and completed firing zone C, that is, the moisture content region, gradually expand, but the moisture content 'kk of unburned zone A reaches a saturated state at approximately 8%, and remains unchanged. However, the water content of 8% water [IK] is maintained and the area is reduced (1
(Refer to the graph in Figure (B)), when viewed in a vertical section, the overall moisture content decreases as the pallet moves. When the combustion zone B reaches the bottom of the pallet and the unburned zone A becomes visible, the moisture content becomes approximately zero over almost the entire vertical section. Therefore, from the above results, conversely, if we can detect the moisture content in the vertical 11g1 for each part of the combustion material on the pallet after the ignition position, from this moisture content, we can determine the combustion front position of combustion zone B,
If it is sandwiched, it is possible to detect the thickness of the unburned @ area. The inventors of the present invention have concluded that the moisture content in the sintered raw material as described above can be accurately, continuously and efficiently measured using a neutron moisture meter.

The present invention was made in view of the above circumstances, and its purpose is to accurately measure the position of the combustion front of the sintered raw material on the pallet by detecting the moisture content of the sintered raw material during firing. It is an object of the present invention to provide a method for monitoring the progress of sintering, which allows precise control of the sintering rate, and which is capable of producing sintered ore with excellent hot reduction powdering index and cold strength.

A sintering status monitoring method according to the present invention includes placing a neutron source and a neutron detector above and below a sintered packed layer during firing, and detects neutrons emitted from the neutron source and transmitted through the sintered packed layer into a neutron detector. It is characterized by detecting the advancing position of the combustion IIg line in the sintered packed bed based on the output of the neutron detector.

Next, the steps of the sintering progress monitoring method according to the present invention (hereinafter referred to as the method of the present invention) will be explained. In general, fast neutrons are slowed down by hydrogen atoms and have the property of becoming thermal neutrons. Therefore, when fast neutrons are emitted toward a substance containing hydrogen atoms, such as a substance containing water, the In other words, whether there is a lot of water or a little water! At t5, the amount converted to thermal neutrons in the material increases or decreases, and as a result, the number of fast neutrons that pass through the material decreases or increases.
By measuring the transmittance of fast neutrons, it is possible to detect the amount of water in a substance. FIG. 2 is a diagram illustrating the above principle. FIG. 2 is an explanatory diagram showing the principle of the method of the present invention. In the figure, 1 indicates a sintered packed bed which is an object to be monitored, and 2 indicates a neutron moisture meter. The neutron moisture meter 2 consists of a neutron source 21, a neutron detector 22, and a display section 28, and includes a neutron #21. Neutron detectors 22ij: are arranged above and below the sintered packed layer 1, and the neutron source 21 is made of Z-241/Be (Americium-241/Berylicum).

2S2Cf (Calfonicum 252) or the like, and as the neutron detector 22, a proportional counter or the like submerged in paraffin is used. From the neutron source 21, alpha rays emitted from the Am-241 that make up the source collided with Be1.
Fast neutrons generated by a mysterious nuclear reaction form a sintered packed layer 1.
Some of the neutrons are decelerated by collisions with hydrogen atoms and become thermal neutrons, and the other part passes through the sintered packed bed 1 and reaches the neutron detector 22. Since the neutron detector 22 is submerged in paraffin, most of the fast neutrons that reach the detector are converted into thermal neutrons by the hydrogen atoms in the paraffin, and the number of thermal neutrons is counted. By determining the counting rate of thermal neutrons by the neutron detector 22, in other words, the number of transmitted fast neutrons, the water content in the sintered packed bed 1 can be detected.

Next, a concrete implementation state of the method of the present invention will be explained. FIG. 3 is a schematic side view of a Dwight Lloyd sintering machine to which the method of the present invention is applied, and FIG. 4 is a partially enlarged side view with a portion cut away. In the figure, 3 indicates a pallet. The pallet 3 has a driving sprocket 31. Idle sprocket 32
The two sprockets 31 and 32 are connected in contact with an endless track formed by a guide rail, etc. arranged between the two sprockets 31 and 32, and the drive sprockets 31 move the two sprockets in the direction of the white arrow. It is designed so that it can be rotated around 32 degrees.

On the front sprocket side, that is, on the ore feeding end side, facing above the moving area of the pallet 3, there is a bedding hopper 33. The charging hopper 34, the ignition furnace 35, and the heat retention furnace 36 are arranged in the above order toward the floating sprocket 32 side, that is, toward the ore discharge end side, and directly below the ignition furnace 35 under the transfer area of the pallet 3. A large number of air collection boxes 37 are arranged in series in the darkness from the to the vicinity of the ore discharge end.

As shown in FIG. 4, the valley pallet 3 has a large number of gray pallets 3C disposed on the upper surface of a rectangular bee-shaped pallet frame formed by reinforcing lips 3a and 3b combined in a vertical and vertical grid pattern. Side play at the required height on both sides) 3
d is installed upright, and wheels 3e, 3e are provided at the bottom of both sides, protruding to the left and right, and the wheels 3e, 3e are placed on guide rails forming an endless track. It is set up. On the pallet 3, the bedding hopper 33, the charging hopper 34 or the rough plate par 3c are charged with bedding ore and sintering raw materials at a uniform height on the ore feeding end side, and in the process of passing through the ignition furnace 35. The surface is ignited, and the heat is retained in the heat retention furnace 36. On the other hand, a suction force from an air blower (not shown) connected to each kite collection box 37 is applied to the lower surface of the pallet 3, causing air to flow downward from the upper surface of the sintering raw material. The sintering material is advanced downward from its surface, and the sintering raw material is completely fired just before the pallet 3 reaches the ore discharge end, and the sintered ore is sent to the next cooling process as sintered ore.

In the apparatus for carrying out the method of the present invention, one or more locations (
In the embodiment, there are air collection boxes 37, which are connected to each other and are located below the moving area of the let 3 (in two places).
A neutron source 21 is mounted between the edges of the pallet 370, and a neutron detector 22 is mounted above the moving area of the pallet 3 on immovable members such as the frame of the sintering machine. The neutron source 21 contains a large amount of hydrogen atoms and is fixed in a shallow storage container 23 made of acrylic resin and having an open top that functions as a shield. By operating the cylinder 24, it can be made to protrude and retract from the upper end of the cylindrical body 25 while being fitted into the acrylic resin cylinder 25. On the other hand, the neutron detector 22 is disposed under a support plate 26 at a position facing the neutron source 21, being immersed in a paraffin bath (not shown) and separated from the neutron source 21 by about 600 cm.

When the air cylinder 24 is operated to push the neutron source 21 above the cylinder 25, the shielding effect of the cylinder 25 is released and the generated high-speed neutrons are projected onto the sintered packed layer 1 from below the pallet 3. , some of them are converted into thermal neutrons on the way, and the rest passes through the sintered packed bed l and reaches the neutron detector 22, and is converted into thermal neutrons by the surrounding paraffin and counted by the neutron detector 22. As a result, the moisture content of the sintered packed layer 1 is detected.

In addition, the fast neutrons emitted from neutron source 2.1 are
It passes through the reinforcing lips 3a, 3b and the great par 3C of the pallet 3, or passes through the air completely unrelated to these and reaches the sintered packed layer l, but the degree of attenuation by the metal material is small; By experimentally determining the degree of capital reduction due to these factors in advance, it is possible to easily correct the amount.

Next, test results regarding the method of the present invention will be explained.

Figure 5 (a) is a graph showing the transition of the combustion zone in the sintered packed bed. The depth is shown by ). Figure 5 (→ is a graph showing the neutron count rate from the ignition of the sintered packed bed to the firing completion point, the horizontal axis shows the time (minutes) from the ignition to the firing completion point, and the vertical axis shows the counting rate (
X10"cpm). In addition, Fig. 5 (
b) The middle vertical line area indicates the combustion zone. In addition, the broken line in the same graph connects the positions where the pallet frame, which is heated as firing progresses, exhibits a temperature of approximately 100°C (hereinafter - front F).
(referred to as FP).

Comparing both graphs, it is clear that as the firing progresses, the distance from the top surface of the sintered packed bed to the combustion front increases as shown in Figure 5 (a); It can be seen that the neutron transmittance, that is, the counting rate increases, and when the combustion front reaches the bottom of the pallet, the counting rate reaches its upper limit, and thereafter shows a constant value regardless of the transition of the combustion zone. That is, as is clear from the above two clears, the combustion front and the counting rate are the period after the W zone and the end of firing, except for the W zone which is a certain period immediately after ignition, and the combustion zone and the counting rate are the period after the W zone and the end of firing. Except for the two zones, the X and Y zones, which are intermediate periods, exhibit a corresponding relationship. The X and Y zones are periods in which the combustion zone and sintering completion zone gradually increase in the sinter-filled JlA layer, and the moisture content in the vertical plane as a whole is open, and the moisture content and the fast neutron count rate change. Of course, the count rate also indicates the position of the combustion front (or combustion zone).

Note that in the W zone, the combustion front (or combustion zone) and the counting rate do not show a corresponding relationship because the moisture content does not substantially change; however, by making appropriate corrections to the counting rate, the combustion front It is possible to detect the position.

As described above, in the method of the present invention, moisture contained in the sintered packed bed is detected by detecting the transmission rate of fast neutrons, and based on this, the position of the combustion front in the sintered packed bed is determined. Since the sintering process is detected, it is possible to accurately and continuously grasp the sintering progress state from the start of firing of the sintered packed bed to the completion of firing, which improves the quality of the sintered ore and improves the quality of the sintered ore. The EJ4 produced by the present invention has excellent effects, such as being able to reduce the amount of ore and greatly improve the yield.

[Brief explanation of drawings]

Figure 1 (a) is a schematic diagram showing the firing progress of the sintered packed bed, Figure 1 (o) is a graph showing the distribution of moisture content in the vertical cross section of each part of the sintered packed bed, and Figure 2 is An explanatory diagram showing the principle of the method of the present invention, FIG. 3 is a schematic side view of Dwight Lloyd sintered camphor to which the method of the present invention is applied, FIG. Figure (A) is a graph showing the transition of the combustion zone in the sintered packed bed, and Figure 5 (B) is a graph showing the neutron count rate from the ignition of the sintered packed bed to the point at which firing is completed. 1... Sintered packed bed 2... Neutron moisture meter 3...
Pallet 21... Neutron source 22... Neutron detector 31... Drive sprocket 3T... Idle sprocket 33... Bedding hopper 34... Charging hopper 35... Ignition furnace 36... Heat retention furnace 37...Air collection box patent Licensed by Akihito Sumitomo Metal Industries, Ltd. Patent attorney Noboru Kono Inu

Claims (1)

[Claims] 1. A neutron source and a neutron detector are placed above and below the sintered packed layer during firing, and the neutrons transmitted from the neutron source through the sintered packed layer are captured by the neutron detector, and the output of the neutron detector is A method for monitoring the progress of sintering in which the progress position of the combustion jMl line in the sintered packed bed is detected based on the percentage.