JPS5910495B2 - How to detect sintered layer depth - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method for producing sintered ore from iron ore using an endless moving grate, in which the sinter layer depth or sinter layer depth profile is detected online. Regarding how to.

As is well known, in modern iron metallurgy, powdered iron ore, lime, and coke are kneaded with an appropriate moisture content, and the sintering raw materials are turned into pseudo-granules using moving grate-type sintering equipment. (Usually D
Dwight Lloyd type sintering equipment known as L sintering equipment is used, and this equipment will be described as an embodiment of the present invention.

) is used as sintered ore as the main raw material. In the iron ore sintering method using the endless moving grate described above, in order to obtain high quality sintered ore that has sufficient crushing strength even at high temperatures, is difficult to powder, and maintains high air permeability,
It is necessary to constantly monitor whether firing is progressing properly according to standards and to appropriately control firing.

For example, in DL sintering equipment, if the pallet movement speed is too fast, sintering will be insufficient.

Since sufficient sintering reaction does not proceed to the lower layer of the tab rivet, the yield decreases and the resulting product has low drop strength. On the other hand, if the moving speed of the pallet is too slow, the sintering reaction will be sufficient, but oxidation will proceed too much and the reduction powdering index will deteriorate, that is, the productivity will drop significantly. As mentioned above, even if we consider only the pallet moving speed as one of the conditions for proper firing, the air permeability of PET changes depending on the state of different raw material compositions, so the pallet moving speed should be adjusted accordingly. The optimal value of also changes. That is, in normal operation, the raw material composition, moisture content, raw material filling degree, etc. constantly change, so it is necessary to change the pallet moving speed accordingly. In other words, it is required to maintain the firing rate at a value determined from past technical experience, but since there is no suitable index for determining the firing rate, conventionally the sinter cake fracture surface in the ore discharge area was Methods were adopted, such as making judgments based on observation results such as the shape, thickness, and brightness of the combustion zone, and operating so that the exhaust gas temperature distribution in the latter half of the strand was constant. In other words, the progress of firing and whether the firing speed is suitable or not can be directly monitored online.
Currently, there is no means to provide effective information for firing control. Therefore, the present inventors researched a method of directly detecting the progress of sintering, and as a result, developed the method of the present invention. A method used in which one or more magnetic detection ends are moved in the width direction and/or length direction of the pallet close to the surface layer of the sintered raw material after ignition, and changes are made as the firing progresses. A method for detecting the depth of a sintered layer, characterized in that the amount of magnetic deviation is detected, and the depth of the sintered layer or the depth profile of the sintered layer is detected from the amount of magnetic deviation, and a method further improved from the above method, that is, an endless method. A method used for sintering iron ore using a moving grate, in which one or more magnetic detection ends are placed close to the surface layer of the sintered raw material after ignition, and the width of the pallet is measured through a measuring interval holding means. Sintering characterized by detecting the amount of magnetic deviation that changes according to the progress of firing while moving in the direction and/or length direction, and detecting the sintered layer depth or the sintered layer depth profile from the amount of magnetic deviation. This is in the layer depth detection method. The present invention will be explained in detail below using the drawings.

Figure 1 shows a well-known DL used to implement the present invention.
This shows a schematic diagram of the sintering equipment, in which 1 is a sprocket wheel, 2 is a bullet, 3 is a bedding ore supply device, 5 is an ignition furnace, 6 is a bedding layer, 7 is an unsintered layer, and 8 is a bedding layer. 9 indicates a layer in which firing is in progress, that is, a combustion zone, and 9 indicates a layer in which firing has been completed, that is, a sintered layer. For convenience of explanation, a part of the pallet 2 is omitted and not shown, but the pallet 2 usually has a sprocket wheel 1 of 1 to 5w! It is moved at a speed of /m. The layer thickness of the sintered raw material on the pallet 2 is about 30 to 50α, and after the sintered raw material is ignited on the surface layer in the ignition furnace 5, it is sucked and aerated downward in the wind box 10 provided at the bottom of the pallet 2. Firing is performed. The sintered zone 8 is usually 2
0~3011a! /1!Moves downward at a speed of 11t,
The ore is controlled to reach the lowest layer in the ore discharge section 11. In the present invention, the speed at which the combustion zone 8 moves downward from the surface layer is referred to as the sintering speed, and the sintering progress refers to the depth of the sintered layer at any position in the bullet's moving direction, that is, the length or width direction.

Further, the distance from the surface of the combustion zone 8 at an arbitrary position is referred to as the combustion zone depth. Furthermore, the sintered layer depth, that is, the sintered layer thickness, of the combusted raw material in the pallet in the width and length directions of the pallet is displayed as the depth from the surface to the interface with the combustion zone, and the shape of the interface is shown. is referred to as a profile. However, when the firing is completed, the thickness of the sintered layer is the same as the bedding layer. Now, whether or not the firing is being carried out satisfactorily is determined by detecting the combustion layer profile in the moving direction of the pallet, that is, the length direction and/or the width direction. It can be determined whether the layer profile matches the reference sintered layer profile or not by comparing it with the reference sintered layer profile. This point will be explained in more detail.

The second diagram schematically shows the progress of firing from the ignition furnace to the ore discharge section.
It can be expressed as shown in the figure.

In the figure, 7 is the unsintered layer, 8 is the combustion zone, and 9 is the sintered layer that has been completely fired.Now, by taking an arbitrary point in the moving direction of the pallet, the combustion zone in the vertical direction A-N is determined. If the intersections of the upper edge 13a and the lower edge 13b of the diagonally shaded portion 13 and the vertical plane 14 are B and B', respectively, the distance between B and B indicates the thickness of the combustion zone 8.

The temperature distribution of the unsintered layer 7, combustion zone 8, and sintered layer 9 is schematically illustrated along the vertical plane 14 as shown in FIG. In FIG. 3, the horizontal axis represents temperature (° C.), and the vertical axis represents the distribution of the unburned layer 7, combustion zone 8, and sintered layer 9, that is, the distribution of the sintered raw material in the thickness direction. By the way, when we investigate the magnetic properties of burnt ore, we find that the magnetic properties change as the temperature changes, as shown in Figure 4. In the figure, the horizontal axis represents temperature (°C) and the vertical axis represents magnetic permeability. As shown in curve 15, there is not much change in magnetic permeability up to 400°C, but at the Curie point near 800°C, magnetic permeability changes significantly. Therefore, when a magnetometer, that is, a magnetic detection end whose output changes in proportion to the change in magnetic permeability, is used, the output change approximates the curve 15.

Therefore, by measuring the magnetic properties of the sintered layer in the vertical direction from near the surface of the sintered layer, it becomes possible to know the firing progress, that is, the depth of the sintered layer. Hereinafter, a method for determining the sintered layer depth using the magnetic detection end will be described in detail.

FIG. 20 is a conceptual diagram of an experiment in which the output of the magnetic detection end is investigated using a device that can arbitrarily increase or decrease the layer thickness of the packed layer 46 made of sintered ore at room temperature, for example, in units of 5011. The magnetic detection end is placed close to the surface layer 46a of the filling layer 46 using a measurement interval of 50 degrees.

Figure 21 is a graph comparing the output of the magnetic detection end with the layer thickness changed, and the horizontal axis is the sintered ore layer thickness (M7IL).
, the vertical axis indicates the output (MV) of the magnetic detection end. As is clear from Fig. 21, as the layer thickness of the sintered ore increases, the curve 47
The output VMM of the magnetic detection end, represented by , increases in proportion to the depth of the sintered layer, as shown in equation (1) below. However, like Z: sintered layer depth, the layer thickness of the sintered layer in actual sintering equipment has a three-dimensional spread, but if you create a calibration curve that shows the relationship with the magnetic detection end output, the magnetic detection end By measuring the output
It becomes possible to know the sintered ore layer thickness, that is, the sintered layer depth.

Next, the theoretical formula for the output of the magnetic detection end is as follows (2
) is shown in the formula.

By the way, the temperature within the sintered layer 9 on the pallet is not constant as shown in FIG. 3, but has a temperature distribution in the layer height direction.

Here, even if the temperature inside the sintered layer has a temperature distribution, if the temperature inside the layer is below 400℃,
As is clear from the relationships shown in FIGS. 4 and 21, the output of the magnetic detection end can be considered to be determined only by the depth of the sintered layer, regardless of temperature. However, as shown in Figure 4, although the magnetic detection end has detection power in the temperature range below the Curie point of approximately 800°C, the output decreases in the high temperature range of 400°C or higher, so temperature correction is required. Therefore, it is preferable to detect the sintered layer thickness within a temperature range of 800° C. or lower. Therefore, the present inventors will accurately estimate the depth of the sintered layer from the surface layer of the sintered layer to an arbitrary temperature surface by investigating in detail the correlation between the output of the magnetic detection end and the temperature pattern within the sintered layer. invented a method. An example of the method will be explained with reference to FIG. 22. Fig. 22 shows the magnetic detection end device of the embodiment shown in Fig. 9, which will be described later, being moved at a speed equal to the moving speed of the pallet in DL sintering equipment, and the magnetic detection end output as the firing depth changes. Although not shown, the depth within the sintered raw material layer immediately below the magnetic detection end is 100W! Lll5OmlL,2
A thermocouple was inserted at the position of OOll and the temperature inside the sintered layer was 300℃, 400℃, 500℃...
・・・・Corresponding to the magnetic detection end output at 800℃,
This diagram illustrates the relationship between the distance (depth) from the surface layer of the sintered layer, the output of the magnetic detection end, and the temperature inside the sintered layer. In FIG. 22, for example, line segment 48 indicates that the internal temperature of the sintered layer is 80.
The line segment 49 represents the relationship between the sintered layer depth at the interface at 0° C. and the magnetic sensing end output, and similarly, the line segment 49 represents the relationship between the sintered layer depth at the interface at a temperature of 700° C. and the magnetic sensing end output. Therefore, the depth of the sintered layer can be easily determined by measuring the temperature at the lower end of the sintered layer, or under conditions where the temperature can be approximately estimated from operational experience or other parameters. If the temperature of the lower end surface of the sintered layer is 700° C., the depth of the sintered layer can be easily estimated from the relationship between the line segment 49 and the magnetic detection end output. In other words, to explain with Fig. 22, the sintered layer depth when the magnetic detection end output is 30 mV is the intersection point q of the horizontal line drawn from the intersection p of the horizontal line passing through the vertical axis 30 m and the line segment 49 and the horizontal axis.
(16511 in this example). According to the research results of the present inventors, it has been confirmed that the relational expression of the line segments shown in Fig. 22 is almost similar under various different operating conditions. By determining this in advance, the sintered layer depth can be accurately estimated from the magnetic detection end output. In other words, the conditions in which the sintering raw material is ignited, the sintering progresses and it changes to sintered ore, and the depth from the surface layer to which it changes to sintered ore, that is, the vertical thickness of the sintered layer, i.e. sintering. Layer depth can be detected at any time and location as a comprehensive comparison of independent points, ie, a sintering pattern, or as a variation over time of each measurement point. Furthermore, since the magnetic detection end detects the above-mentioned magnetic properties, it is preferable from the viewpoint of detection accuracy to set it closer to the surface layer of the sintered raw material. However, due to differences in the function of the magnetic detection end itself, the presence or absence of equipment that causes magnetic changes in the measurement field, differences in the physical properties of the object to be measured, the amount and layer thickness of the object to be measured, or the magnitude of the measurement effect. Therefore, the measurement position or scanning position of the magnetic detection end should be determined. In the present invention, providing a magnetic detection end close to the surface layer of the sintered raw material is used in the above-mentioned meaning, and determining the profile of the sintered layer depth of the sintered raw material layer refers to the width of the pallet as described above. This means determining the shape of the interface between the sintered layer and the combustion zone in the direction and/or length direction, that is, determining the shape of the continuous interface.
Furthermore, since the magnetic permeability changes significantly in each part of the combustion zone, the sintered layer in the present invention is not clearly separated from the combustion zone 8 as shown as the sintered layer 9 in FIG. It should be understood that this refers to a layer in which a significant change in magnetic permeability has occurred when based on the sintered raw material of .

Therefore, it can usually be considered to be a layer that has been converted to sintered ore. Next, details of the magnetic detection end used in the present invention will be explained. Now, in the present invention, as mentioned above, a well-known magnetic detection end can be used as long as it has the function of detecting changes in magnetic permeability in close proximity to the surface layer of the sintered raw material, but in particular, the present inventor invented and applied for a patent application. It is more appropriate to use the principle of the magnetic detection end filed in Japanese Patent Application No. 100995/1982, and an embodiment of the magnetic detection end suitable for the purpose of the present invention will be described in FIG.

As mentioned above, in order to use the magnetic detection end in an open state in equipment composed of iron structures such as DL sintering equipment, magnetic influences from fixed structures and moving structures such as cranes must be avoided. It is necessary to devise a method to eliminate only the change in the magnetic properties of the sintered raw material. The magnetic detection terminal shown in FIG. 5 has a magnetic core divided into two parts M, , M2, and reversed windings are applied to the two parts so that they act differentially.

Therefore, two switching transistors Trl and Tr2
When excited, in this example, oscillations of around 40 degrees occur due to the nonlinearity of the magnetic cores M1 and M2. At this time, the magnetic core M,,
If an increase or decrease in the magnetic substance, that is, a change in the firing progress described above in the present invention occurs in the vicinity of either one of M2, the magnetic oscillation will be distorted because it is generated by the built-in excitation magnet G1, and a DC component proportional to the amount of distorted magnetism will occur. is output. Tl,T
2 shows the output terminal, E is the power supply, and Rl and R are the adjustment resistors, but some parts of the circuit such as the differential winding are omitted for convenience to avoid complication, and the connection terminals P1 to P, In the subsequent windings, the connections after P1 to P3 and the connections after P, -P, and after are the same. 6 and 7 respectively show the output waveform in a magnetically balanced state and the output waveform in a magnetically unbalanced state at the magnetic detection end described above, and in the embodiment of the present inventors, the period T .

was approximately 25μ8eC. Also, the level difference is 1. becomes the DC component. Next, FIG. 8 shows a schematic diagram of an embodiment of an apparatus for carrying out the method of the present invention.

In the figure, reference numeral 16 denotes a magnetic detection end, which is installed so as to face the vicinity of the surface 9a of the sintered layer 9 via a fixing device 50 that is detachable from a beam 51 attached to a moving traveling device (not shown). .

Ml and M2 are the aforementioned two-divided magnetic cores, and G1 is an exciting magnet. The magnetic cores MO, M2, excitation magnet G1, etc. are made of non-magnetic material, for example stainless steel case 5.
2, which is shown in longitudinal section in the figure. If the vertical vibration of the pallet 2 is small and the layer thickness of the sintered raw material is stable, and as a result, the distance variation between the surface 9a of the sintered layer 9 and the magnetic detection end 16 is extremely small, as shown in FIG. It is possible to use one or more magnetic detection ends 16 by moving them in the width direction and/or length direction of the pallet.

In other words, the firing progress at the measurement location is detected in advance by actually taking samples, etc., and compared with a set reference sintered layer profile at that location, or by comparing changes in detected values, the suitability of firing is determined. You can know.
Next, FIG. 9 shows another embodiment of the present invention in which a magnetic detection end is provided via a measurement gap holding means. In FIG. 9, reference numeral 17 denotes a distance detection end of a level holding device 18 for keeping the separation distance between the magnetic detection end 16 and the surface 9a of the sintered layer 9, that is, the measurement interval, approximately constant. A distance meter of, for example, an air micrometer type or an optical type attached to the sintered layer detects a change in distance to the surface 9a of the sintered layer and transmits a signal to the distance adjustment control device 22 via a conductive wire 21. The distance adjustment control device 22 compares the magnetic detection end 16 with a preset and stored reference measurement interval, and sends a correction command via a conductive wire 23 to a magnetic detection end lifting device 24, such as a barometric pressure, hydraulic pressure, or balance type. , and operates so that the magnetic detection end 16 always maintains a set measurement interval with the surface layer 9a of the sintered layer. The distance detecting end 17 is shown as a non-contact type, but a contact type such as a wheel that rolls in contact with the surface of the sintered raw material may also be used. Then, using the apparatus of the embodiment shown in FIG.
The graph in Figure 10 shows an example in which the magnetic detection end output is determined as the firing depth changes while the device is moved at the same speed as the pallet movement speed in DL sintering equipment, and then compared with the theoretically determined firing progress. Shown below. In the figure, the horizontal axis is the pallet movement distance 00, and the vertical axis is the magnetic detection end output (MV).
Curve 25 is the magnetic detection end output, and curve 26 shown by a dotted line is the firing speed of 20m1/7! i! The change in firing depth calculated theoretically as t is the curve 26. It has been confirmed that this curve 26 approximates the actual value based on research such as bed temperature measurements in actual equipment and cross-sectional temperature distribution in the ore discharge area. It is something that In this example, the wave-like vibrations in curve 25 were caused by the presence of steel beams of the building that supported the wind boxes at 4 m intervals;
It is clear that the firing progress can be accurately estimated from

Figure 11 shows a case where the movement of pallets was stopped and sintering work was carried out (this is a typical situation in terms of operating conditions, and corresponds to a temporary stoppage of pallet movement due to equipment failure).

Curve 27 shows the output of the magnetic detection end obtained at time T, when the movement of the pallet stopped and firing progressed at time T. At time T2, the output is saturated, indicating that sintering is complete. In this example, detection ended at time T3, but the sampling results confirmed that the entire layer had become a sintered layer at time T2, and it is clear that curve 27 can be treated as indicating the firing progress at the time of detection. It became. In this example, it is approximately 10m from the ignition furnace.
The measurement was performed at a position close to the moving direction, the time from time t1 to time T2 was about 10 minutes, and the thickness of the sintered layer was about 40 mm. It was hot. Based on the above results, the present inventors conducted scanning in the width direction and/or length direction of the pallet using one or more magnetic detection ends, that is, a plurality of magnetic detection ends, to determine the sintered layer depth or the sintered layer depth. It was invented to detect the profiles of people.

FIGS. 12 and 13 are schematic top views of the pallet and illustrate the situation in which the magnetic detection end 16 is moved in the width direction of the pallet while scanning. As shown in the figure, when the magnetic detection end is moved like 16a, 16b, and 16c, the sintered layer depths 28a, 28b, and 28c are obtained for each measurement position, and when these are continuously measured, the sintered layer depth in the width direction is A layer depth profile 29 is obtained. FIGS. 14 and 15 show examples in which the sintered layer depth profile was similarly determined by scanning in the length direction of the pallet.
In this way, the sintered layer depth and sintered layer depth profile at any position can be determined. In Figs. 13 and 14, 16d to 16z indicate measurement positions, and 2
8d to 28z indicate the sintered layer depth at the measurement location, and curve 30 shows the sintered layer depth profile along the length of the pallet. In the present invention, the technical scope of the present invention is continuous measurement rather than measurement at fixed measurement positions as shown in FIGS. 12 to 14. Next, FIG. 16 shows an embodiment of the apparatus used to scan the pallet in the longitudinal direction.

In the figure, reference numeral 31 denotes a ceiling beam, and 32 and 32'' support beams supporting rails 33 and 33, which extend in the length direction of the pallet 2 and are fixed to the ceiling beam 31.

The frame 34 is mounted on rails 33, 33'11 through bearing stands 35, 35'' and wheels 36, 36' so that it can run freely. 37 is an electric motor for running, which has a pinion 38 and a drive shaft 39.
, the wheels 36, 36 via gear devices 40, 40''
Rotate '.

16, 16 male support rods 41, 41', holding device 42,
This is a magnetic detection end installed on the pedestal 34 via 47.

43 and 4 indicate the work floor, and 44 indicates the sintering raw materials charged to the pallet 2.

When the pallet 2 is scanned in the longitudinal direction with the above-mentioned apparatus, two longitudinal sintered layer depth profiles as shown in FIG. 15 can be obtained. By comparing the respective Q-shape formation depth profiles, it is possible not only to accurately know the balance of firing on both sides of the pallet, but also to quickly detect whether firing is appropriate or not in the length direction. becomes. In FIG. 16, the traveling electric motor 37
The control mechanism and the signal processing device of the magnetic detection ends 16, 16'' are not shown in the figure, but they may be controlled by a wireless remote control or a push button switch using a conductive wire, within the range that does not deviate from the purpose. Therefore, any control device may be used.

Further, the signal processing device can be constructed by appropriately employing known electronic circuits. Although FIG. 16 shows an example of scanning in the length direction of the pallet, the scanning is not limited to this, but scanning in the width direction of the pallet or a combination of width and length directions can be adopted as appropriate. Yes, Figure 17~
In the schematic top view of the palette in FIG.
As shown in 5a to 45p, the depth of the sintered layer and/or its profile obtained by changing the position and scanning alone or as a group becomes extremely accurate, providing information useful for operational control, and If the layer depth profile differs significantly from the standard sintered layer depth profile determined empirically or theoretically, various control factors such as the moving speed of the grate and the charging of sintering raw materials should be immediately adjusted. quantity, charging distribution, sintering raw material composition, wind box opening degree, ignition strength,
It is possible to optimize the operation by appropriately controlling the moisture content of the sintering raw material.

As mentioned above, the present invention not only provides important information online for determining whether firing is appropriate, but also provides information on how changing control factors affects firing. This provides an important means of searching for information.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the DL sintering equipment, Figure 2 is a schematic diagram to explain the firing progress, Figure 3 is a diagram to explain temperature distribution in the thickness direction of the sintering raw material, and Figure 4 is temperature and magnetic permeability. FIG. 5 is a schematic diagram of the magnetic detection end circuit configuration used to implement the method according to the present invention, and FIGS. 6 and 7 are graphs showing the relationship between the output and the magnetic detection end output. Output waveform and schematic diagram showing output waveform in magnetic unbalance state, No. 8
Figure 9 is a schematic explanatory diagram of the schematic configuration and operation procedure of different magnetic detection ends used to carry out the method of the present invention, and Figure 10 is a proportional relationship between the firing progress and the output of the magnetic detection end. The graph shown in Fig. 11 shows the case where the magnetic detection end is fixed,
A graph showing the magnetic detection end output obtained when firing was performed with the pallet stopped moving. 12, 13, 14, and 15 are explanatory diagrams of the scanning detection procedure according to the present invention, FIG. 16 is an explanatory diagram of the schematic configuration of the apparatus used to carry out the method of the present invention, and figure,
FIG. 18 and FIG. 19 are explanatory diagrams of the scanning locus according to the present invention,
Figure 20 is a conceptual diagram showing how to investigate the output of the magnetic detection end, Figure 21 is a graph showing the relationship between the sintered ore layer thickness and the output of the magnetic detection end, and Figure 22 is the relationship between the output of the magnetic detection end and the sintered layer temperature. It is a graph showing a relationship. 1...Sprocket wheel, 2...Pallet, 3...Bedding layer supply device, 4...Sintering raw material supply device, 5...
...Ignition furnace, 6...Bedding layer, 7...
Unsintered layer, 8... Combustion zone, 9... Sintered layer, 10... Wind box, 16, 16'
-... Magnetic detection end, 17... Distance detection end, 18... Level holding device, 19...
Support rod, 20... Support beam, 21, 23...
... Conductive wire, 22 ... Distance adjustment control device,
24... Magnetic detection end lifting device, 31...
- Ceiling component beam, 32, 37... support beam, 33, 33'... rail, 34... frame, 37... electric motor for traveling.

Claims (1)

[Claims] 1. A method used for sintering iron ore using an endless moving grate, in which one or more magnetic detection ends are placed on a pallet close to the surface layer of the sintered raw material after ignition. The sintered layer depth or the sintered layer depth profile is detected from the magnetic deviation amount by detecting the amount of magnetic deviation that changes as the firing progresses while moving it in the width direction and/or length direction. Detection method of sintered layer depth. 2. A method used for sintering iron ore using an endless moving grate, in which one or more magnetic detection ends are placed close to the surface layer of the sintered raw material after ignition via a measurement interval holding means. While moving the pallet in the width direction and/or length direction, the amount of magnetic deviation that changes as firing progresses is detected, and the sintered layer depth or sintered layer depth profile is detected from the amount of magnetic deviation. A method for detecting the depth of the sintered layer.