JPS5910497B2 - Sintered layer depth detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates primarily to a method for detecting the depth of a sintered layer used in a means for sintering iron ore.

As is well known, in modern iron metallurgy, iron ore, lime,
Coke powder is kneaded with an appropriate moisture content, and the sintering raw material is turned into pseudo-granules using a moving grate type sintering equipment (Dwight Lloyd type sintering equipment, commonly known as DL sintering equipment). The present invention will be described using this equipment as an embodiment of the present invention.

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

For example, in DL sintering equipment, if the moving speed of the pallet is too fast, sintering will be insufficient.In other words, the sintering reaction will not progress to the lower layer of the bed, resulting in a lower yield and lower product yield. It has low fall 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 atomization 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 the bed changes with different raw material compositions, so the pallet moving speed must be adjusted accordingly. The maximum value of will also change. 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 non-mine area was used. 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. That is, currently there is no means to directly monitor the progress of firing and the suitability or unsuitability of the firing speed online and to provide effective information for firing control. As a result of research into a method for directly detecting the progress of sintering, the present inventors developed the method of the present invention.The gist of the present invention is a means for sintering iron ore using an endless moving grate. A method used for A method for detecting the depth of the sintered layer to determine the depth of the sintered layer, and a method that is a further development of the above-mentioned method, that is, a method used for iron ore sintering means using an endless moving grate. A sintered layer characterized in that a magnetic detection end is provided via a measurement interval holding means to detect the amount of magnetic deviation that changes as firing progresses, and the depth of the sintered layer is determined from the amount of magnetic field deviation. It's in the 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 figure shows a schematic diagram of the sintering equipment, in which 1 is a sprocket wheel, 2 is a pallet, 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. Although a part of the pallet 2 is omitted and not shown for convenience of explanation, the pallet 2 is normally moved by the sprocket wheel 1 at a speed of 1 to 5 m/Wt. The layer thickness of the sintered raw material on the pallet 2 is about 30 to 50 m (approximately 30 to 50 m), and after the sintered raw material is ignited on the surface layer in the ignition furnace 5, it is sucked downward in the wind box 10 provided at the bottom of the pallet 2. The combustion zone 8 is usually 2
It moves downward at a speed of 0 to 3011/drive and is controlled to reach the lowest layer at the ore discharge section 11. In the present invention, combustion zone 8
The speed at which the sintered layer advances downward from the surface layer is called the firing speed, and the firing progress refers to the depth of the sintered layer at any position in the direction of movement of the pallet.

Further, the distance from the surface of the combustion zone 8 at an arbitrary position is referred to as the combustion zone depth. Now, whether or not the firing is being performed well is determined by detecting the depth of the sintered layer in the moving direction of the pallet.
The sintered layer depth that is empirically known from past operational research, that is, the reference sintered layer depth, or the aforementioned sintered layer depths measured at multiple independent points can be compared with each other. You can find out by looking at it.

This point will be explained in more detail.

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

In the figure, 7 is an unsintered layer, 8 is a combustion zone, and 9 is a 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-A'' is determined. If the intersections of the upper edge 13a and the lower edge 13b of the diagonally shaded portion 13 indicating 8 with the vertical plane 14 are B and B', respectively, then B-B'
The distance between them will indicate the thickness of the combustion zone 8.

The temperature distribution of the unburned 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 sintered 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 the magnetic permeability up to 400°C, but the magnetic permeability changes significantly at the Kyuri Δ point near 800°C. 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 crystal layer. Hereinafter, a method for determining the sintered layer depth using the magnetic detection end will be described in detail.

FIG. 12 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 28 made of sintered ore at room temperature by an arbitrary thickness, for example, in units of 5011. 501 from the surface layer 28a of the filling layer 28! The magnetic detection ends are placed close to each other using a measurement interval of l.

FIG. 13 is a graph in which the layer thickness is varied and compared with the output of the magnetic detection end, where the horizontal axis shows the sintered ore layer thickness (11) and the vertical axis shows the output (MV) of the magnetic detection end. As is clear from FIG. 13, as the layer thickness of the sintered ore increases, the output VMM of the magnetic detection end shown by the curve 29 increases in proportion to the depth of the sintered layer, as shown in equation (1) below. Similarly, 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, you can easily measure the magnetic detection end output. Therefore, it becomes possible to know the sintered ore layer, that is, the depth of the sintered layer. Next, a theoretical equation regarding the output of the magnetic detection end is shown in equation (2) below.

By the way, as shown in FIG. 3, the temperature within the sintered layer 9 on the pallet is not constant 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 13, 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 about 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 this method will be explained with reference to FIG.

Fig. 14 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 sintering depth changes. Although not shown in the figure, when calculating the
Thermocouples are inserted in the 0U120011 position and connected simultaneously, and the temperature inside the sintered layer is 300℃, 400℃, 500℃・
......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 was determined by matching the output of the magnetic detection end at 800℃. This is what is illustrated. In FIG. 14, for example, line segment 30 represents the relationship between the sintered layer depth and the magnetic detection end output at the interface where the internal temperature of the sintered layer is 800°C, and similarly, line segment 31 represents the relationship between the sintered layer depth and the magnetic detection end output at the interface where the internal temperature of the sintered layer is 700°C. It shows the relationship between the depth and the output of the magnetic detection end, and 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 operating experience or other parameters. becomes possible. 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 31 and the magnetic detection end output. In other words, to explain with reference to FIG. 14, when the magnetic detection end output is 30 m, the sintered layer depth is the depth ( In this example, it is calculated as 1651!). According to the research results of the present inventors, it has been confirmed that the relational expression of the line segments shown in Fig. 14 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, that is, the sintered ore. Determine the formation depth at any time and position by comprehensively measuring multiple independent points.
It can be detected as a comparison, that is, 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 that it be installed closer to the surface layer of the sintered raw material. However, due to differences in the functions of the magnetic detection end itself, the presence or absence of equipment that causes magnetic changes in the measurement field, or differences in the physical properties of the object to be measured, the amount and layer thickness of the object to be measured, etc. The measurement position should be determined. In the present invention, the provision of a magnetic detection end close to the surface layer of the sintered raw material is used in the above-mentioned meaning, and the determination of the sintered layer depth is used at any position in the moving direction of the pallet as described above. This refers to detecting the thickness of the sintered layer and detecting changes in the thickness of the sintered layer as the firing progresses, as necessary. Furthermore, since the magnetic permeability changes significantly in each part above the combustion zone, the sintered layer in the present invention refers to the combustion zone 8 as shown as the sintered layer 9 in FIG.
Rather, it should be understood that it refers to a layer in which a significant change in magnetic permeability has occurred when based on the sintered raw material before firing.

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. In the present invention, as described above, any 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. It is more appropriate to utilize the principle of the magnetic detection end filed in Japanese Patent Application No. 100995/1983, 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 end shown in FIG. 5 has a magnetic core divided into two parts M1 and M2, and windings are reversed so that the two parts act differentially.

Therefore, two switching transistors Tr, Tr2
In this example, oscillations of around 40 mm occur due to the nonlinearity of the magnetic cores Ml, M2.
If any of the above causes an increase or decrease in the magnetic substance in the vicinity of one of them, that is, a change in the firing progress described above in the present invention, distortion will occur in the magnetic oscillation due to the built-in excitation magnet G1, resulting in a direct current component proportional to the amount of distorted magnetism. is output. Tl, T,
indicates the output terminal, E is the power supply, and R, , R2 are the adjustment resistors, but some parts of the circuit such as the differential line are omitted for convenience and convenience to avoid complication, and the connection terminals P, ~ In the windings after P7, the connections after P1 to P3 are the same as the connections after P5 to P and after. 6 and 7 respectively show the output waveform in a magnetically balanced state and the output waveform in a magnetically unbalanced state at the above-mentioned magnetic detection terminal, and in the embodiment of the present inventors, the period T. (approximately) 25 μSec.

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 near the surface 9a of the sintered layer 9 via a fixing device 50 which is detachably attached to a beam 51 attached to a support column (not shown). Ml and M2 are the aforementioned two-divided magnetic cores, and G1 is an exciting magnet. Magnetic core Ml, M2
The excitation magnet G1 and the like are housed in a case 52 made of a non-magnetic material, for example stainless steel, which is shown in a longitudinal cross-sectional view 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, the result will be as shown in FIG. The magnetic detection end 16 can be fixed in this way and used. That is, it is possible to know whether firing is appropriate or not by detecting the firing progress at a fixed measurement location in advance by actually taking samples and comparing it with a set standard firing progress at that location. 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. For example, a distance meter of an air micrometer type or an optical type is attached to the sintered layer and detects a change in distance from 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 reference measurement interval set and stored in advance, and sends a correction command via a conductive wire 23 to a magnetic detection end lifting device such as an air pressure, hydraulic pressure, or balance type. 24, and the magnetic detection end 16 is always on the surface 9a of the sintered layer.
It operates to maintain the set measurement interval. Although the distance detecting end 17 is shown as a non-contact type, it is also possible to use a contact type that uses wheels that roll in contact with the surface of the sintered raw material to maintain a direct measurement interval. .
Using the apparatus of Example 0 shown in FIG. 9, while moving the apparatus at a speed equal to the moving speed of the bullet in the DL sintering equipment, the output of the magnetic detection end as the sintering depth changes is determined, and then theoretically An example of comparison with the determined firing progress is shown in the graph of FIG. In the figure, the horizontal axis is the pallet movement distance (m), the vertical axis is the magnetic detection end output (MV), and the curve 2
5 is the magnetic detection end output, and a curve 26 shown by a dotted line shows the firing depth change theoretically determined by assuming the firing rate as 2011/Mm. The curve 26 is the temperature measurement inside the bed in actual equipment.
It has been confirmed through research on the cross-sectional temperature distribution in the ore discharge area that it approximates the actual value. 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, and it is clear that the firing progress can be accurately estimated from curve 25. be.

Figure 11 shows the results obtained when sintering work is carried out with the movement of pallets stopped (this is an irregular situation in terms of operational conditions, and involves a temporary stoppage of pallet movement due to equipment failure). The output of the magnetic detection end is shown by a curve 27, which indicates that the movement of the pallet stopped at time t1 and firing progressed. 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, the measurement is performed at a position approximately 10 m away from the ignition furnace in the moving direction, and from time t1 to time T
The time to 2 is about 10 minutes, and the thickness of the sintered layer is about 4
0c! It was n. As explained in detail above, according to the method of the present invention, it is possible to reliably detect the dawning state online, which contributes to improving operational methods for the purpose of improving productivity, energy saving, and quality. It is extremely large.

[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. Figure 5 is a schematic diagram of the configuration of the magnetic detection terminal circuit used to implement the method according to the present invention, and Figures 6 and 7 are the output in a magnetically balanced state. A schematic diagram showing waveforms and output waveforms in a magnetically unbalanced state, FIG.
Fig. 9 is a schematic explanatory diagram of the schematic configuration and operation procedure of different magnetic detection terminals used to carry out the method of the present invention, and Fig. 10 shows the proportional relationship between the firing progress and the output of the magnetic detection terminal. The graph shown in Figure 11 is a graph showing the magnetic detection end output obtained when firing was performed with the magnetic detection end fixed and the pallet stopped moving, and Figure 12 shows the procedure for investigating the output of the magnetic detection end. 13 is a graph showing the relationship between the sintered ore layer thickness and the magnetic detection end output, and FIG. 14 is a graph showing the relationship between the magnetic detection end output and the sintered layer temperature. 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... Magnetic detection end, 17.
... Distance detection end, 18 ... Level holding device, 19 ... Support rod, 20 ... Support beam, 21, 23 ... Conductive Line, 22...
- Distance adjustment pedestal device, 24...Magnetic detection end lifting device.

Claims (1)

[Claims] 1. A method used for sintering iron ore using an endless moving grate, in which a magnetic detection end is provided close to the surface layer of the sintered raw material after ignition, and the method A method for detecting the depth of a sintered layer, the method comprising: detecting the amount of magnetic deviation that changes depending on the amount of magnetic field deviation; and determining the depth of the sintered layer from the amount of magnetic deviation. 2. A method used for sintering iron ore using an endless moving grate, in which a magnetic detection end is provided close to the surface layer of the sintered raw material after ignition via a measuring interval holding means, and the method is used to monitor the progress of sintering. A method for detecting the depth of a sintered layer, characterized by detecting the amount of magnetic deviation that changes accordingly, and determining the depth of the sintered layer from the amount of magnetic field deviation.