JPS5941493B2 - Sintered ore manufacturing method and equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in a method and apparatus for producing sintered ore using a Dwight Lloyd sintering machine.

In the Dwight Lloyd type sintering machine, the surface layer of the mixed raw materials is ignited in the ignition furnace, and then air is sucked downward, so that the sintering reaction in the mixed raw materials gradually moves from the surface layer to the lower layer. It takes approx. 2 to complete the sintering reaction throughout the layer.
It usually takes 0 minutes.

The optimal operation direction for producing sintered ore is to maintain the quality of the obtained sintered ore, maximize productivity, and minimize coke consumption. It goes without saying that it is better to keep the sintering reaction time as short as possible within the range of maintaining the quality of the sintered ore, and to minimize the amount of coke added as fuel.

In the Dwight Lloyd type sintering machine, various actions are taken to improve the granulation properties of the compounded raw materials and actions are taken in the charging method to improve the air permeability of the sintering bed and improve productivity. Operations are being implemented to reduce the coke consumption rate by reducing the amount of coke in the fuel by using more coke oven gas for heating and heat retention, or by increasing the thickness of the upper layer and the amount of heat retained to improve the yield.

However, the former raw materials, coke, and coarse grained limestone can be expected to increase production efficiency by improving air permeability, but the problem is that the coke consumption rate worsens due to a decrease in the strength and yield of sintered ore. There is.

Furthermore, if a large amount of coke oven gas is used for heat retention in the ignition furnace, the yield in the upper layer will be improved and the coke consumption rate will be good, but there will be a significant decrease in production efficiency due to the extension of sintering time. well known.

In other words, in the production of sintered ore, it is extremely difficult to simultaneously increase production efficiency with the aim of achieving high productivity and energy savings while reducing coke consumption.
The current situation is that there is still no established operating method that combines high quality.

The present invention was made in view of these circumstances, and makes possible a sintering operation method that is oriented toward improving productivity, significantly reducing coke consumption, improving quality, and reducing NOx.

That is, the present invention has the following advantages: (1) A plurality of blended raw materials with different coke contents are placed on a pallet so that the raw materials with low coke content are in the lower layer and the raw materials with high coke content are in the upper layer. A method for producing sintered ore, characterized in that only the upper layer of the charge on the pallet filled in this way is dried and preheated by hot air suction, and then ignited and sintered, and (2) Dwight Lloyd sintering. At the machine, a plurality of ore feeding devices are installed in the direction in which the pallets move to supply mixed raw materials onto the pallets, and a hot air supply device is installed between the last ore feeding device of these ore feeding devices and the ignition furnace. The gist of the present invention is a sintered ore manufacturing apparatus, characterized in that it is configured to guide high-temperature gas discharged from a cooler and/or a wind box of a sintering machine to the hot air supply apparatus.

The present invention will be described in detail below based on the drawings.

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

As shown in FIG.
The material is continuously supplied onto the pallet 7 via the drum feeder 3 and the sloping plate 5, and the sprocket 4 on the raw material feeding side is rotated to move the charge (filled mixed raw materials) 8 on the pallet γ at low speed. from the wind boxes 9, 9, .
2, the upper surface of the charge 8 is ignited in the ignition furnace 6, and the charge 8 on the pallet 7 is continuously sintered so that the sintering reaction is completed over the entire layer while it reaches the ore discharge section. In a Dwight Lloyd type sintering machine for producing ore, a plurality of ore feeding devices are installed in the advancing direction of the pallet 7 to supply raw materials to the pallets 1 and 7. In other words, in FIG.
Separately from the ore feeding device consisting of the drum feeder 3 and the sloping plate 5, an ore feeding device consisting of the hopper 2' and the drum feeder 3ζ sloping plate 5' is installed on the upstream side of the ore feeding device, and the ore feeding device on the upstream side The blended raw material 1' with a low coke content is supplied onto the pallet 7 from the device, and the blended raw material 1 with a high coke content is supplied from the ore feeding device installed on the downstream side. The raw material, ie, the charge 8, is continuously fed in layers such that the coke content is high in the upper layer and lower in the lower layer.

Even when three ore feeding devices are installed, the coke content is similarly fed so that the lower the layer, the lower the coke content.

Only the upper layer of the raw materials supplied onto the pallet is dried and preheated before the upper surface is ignited.

That is, hot air is blown from a hot air supply device 19 provided between the ignition furnace 6 and the ore feeding device at the last stage, and air is sucked in from below to dry and preheat only the upper layer of the charge 8.

Charge 8 in which only the upper layer is dried and preheated in this way
enters the ignition furnace 6, where the L layer portion of the charge is ignited, and after ignition, sintering is performed by sucking cold air from the ignition furnace 6 to discharge.

In the hot air supply device 19 according to the present invention, the cooler 1 of the sintering machine
It is advantageous to use the hot air obtained from 6 and also the hot exhaust gas obtained from the wind box 10.

That is, high-temperature exhaust gas of up to 500°C is obtained from the cooler 16, and conventionally it was dissipated into the atmosphere without being used. An exhaust stack from which air can be obtained is selected, and high-temperature air is supplied from there to the hot air supply device 19 through the conduit 21.

The temperature of the supplied air is 10.0°C or higher, preferably 20°C.
The temperature should be 0°C or higher and 400°C or lower due to restrictions on the use of the blower, and the dust content should be 0.2g/Nm or less, preferably 0, to prevent problems caused by dust such as dust accumulation in conduits and hot air supply equipment and nozzle clogging. It is effective to set it to .1 g/Nm or less.

When using high-temperature exhaust gas in the main duct 10, select a position where exhaust gas at a predetermined temperature can be obtained through the introduction pipe 20, and then operate the flow rate adjustment valve 18, dust remover 11', and suction blower 12'.
, supplies hot gas to the hot air supply device 19 via the conduit 22.

Further, the exhaust from the cooler 16 and the high-temperature exhaust gas in the main duct 10 may be used individually, or both may be used simultaneously.

It is also possible to mix the two in advance and supply the mixture to the hot air supply device 19.

In the present invention, the reason why a plurality of ore feeding devices for supplying mixed raw materials onto the pallet is installed in the direction in which the pallet moves is that when the sintering reaction progresses from the upper layer to the lower layer on the pallet,
In order to correct the thermal imbalance in which the upper layer of the charge 8 has insufficient heat while the lower layer has an excessive amount of heat, the coke mixing ratio of the upper and lower layers of the charge 8 has been adjusted to the upper layer. It is necessary to feed the blended raw materials in layers from pallet 1 to the top so that the bottom layer is small.

Changing the coke mixing ratio in the thickness direction of the charge on the pallet in this way is not only effective in correcting the above-mentioned thermal imbalance, but also has the effect of the hot air supply device described below. Due to the synergistic effect with
The coke consumption rate can be reduced, the quality and productivity of the obtained sintered ore can be improved, and the generation of NOx can also be suppressed.

That is, from the hot air supply device 19 according to the present invention, 30
High-temperature gas of about 0°C is blown onto the upper layer of the charge, drying and preheating only the upper layer of the charge 8, and then igniting it in the ignition furnace 6. Drying and preheating of the upper layer prevents the destruction of pseudo particles in the upper layer of the charge at the time of ignition, prevents deterioration of ventilation in this area, and increases the amount of sensible heat brought in by supplying hot air, which increases the temperature of the upper layer. This has the effect of improving quality.

In other words, when the blended raw materials 8 charged into the pallets 7 are rapidly heated in the ignition furnace 6, which is at a high temperature of 1000°C or more from room temperature, the upper surface of the charged materials receives a large thermal shock, and as a result, the loading The pseudo particles on the surface of the container are destroyed, resulting in poor air permeability, which affects until the end of sintering and increases the sintering time.However, in the present invention, the ignition furnace 6 Since the pseudo particles in the upper layer of the charge are dried and preheated by hot air before entering the charge, rapid evaporation of moisture in the ignition furnace and destruction of pseudo particles by the heat bomber can be alleviated, and pseudo particles in the upper layer can be prevented from collapsing. This prevents the deterioration of air permeability caused by this, and since the drying/preparation zone is expanded, the width of the moisture condensation zone with high airflow resistance is narrowed, improving the overall air permeability and shortening the sintering time. Furthermore, in the conventional sintering force method, the sintering reaction was carried out with almost no drying zone in the upper layer of the charge. However, in the present invention, the surface layer of the charge is dried and preheated by the hot air supply device before entering the ignition furnace, so that the sintered ore is dried and preheated before the sintering reaction begins. A preheating zone occurs and the quality of the upper layer improves.

Furthermore, since the upper layer has a higher proportion of coke as a heat source than the lower layer, the thermal deficiency is further eliminated, and the synergistic effect of these effects further improves the quality of the upper layer. The adverse effects caused by the expansion of the heat pattern can be eliminated by reducing the proportion of coke mixed in the lower layer. The sintering time can be further shortened by improving air permeability by preventing the expansion of the heat pattern toward the lower layer.

Example: Coke, return ore, and water were added to the blended raw materials and mixed and granulated.
Sintered ore was produced in a 9 test pot under a negative pressure of 1700 mmAq.

Tables 2 and 3 show the raw material brands, blending ratios, and particle size compositions.

As shown in Table 1, the test conditions were as follows: In the method of the present invention, the blended raw materials were divided into two equal parts in the height direction, and the coke blending ratio in the upper layer was 34%, and the coke blending ratio in the lower layer was 30%.

Then, before igniting, 300℃ hot air is applied to the surface layer of the blended raw materials.
After spraying for a minute, it was ignited and sintered.

For comparison, we used the conventional method, Comparative Example 1 (mixed raw materials in a single layer and no preheating before ignition), Comparative Example 2 (mixed raw materials in a single layer and with preheating), and Comparative Example 3 (mixed raw materials in two layers and preheated). (none) was also tested.

The test results are described below.

(1) Wind speed passing through the raw material layer Figure 2 shows the relationship between the wind speed passing through the raw material layer and the elapsed time from ignition.

As is clear from this figure (temperature of suction hot air before ignition: 300°C), when using the method of the present invention, the above conventional method (Comparative Example 1
The wind speed passing through the raw material layer was faster than that of any of the methods 3) to 3), and therefore the sintering time was the shortest.

(2) Figure 3 shows the temperature change in the layer for the Hea 1 pattern, with the vertical axis representing the temperature and the horizontal axis representing the elapsed time after ignition.

This heat pattern was measured using a pot testing device with a layer thickness of 400m7rL by inserting thermocouples into the upper, middle, and lower layers at 100-square intervals.Examples are shown in comparison with the conventional method above. There is.

From Figure 3, Comparative Example 2, in which the -L layer was preheated and sintered with hot air at 300°C before ignition in a single layer, had a coke blending ratio 0.2% lower than Comparative Example 1. Despite this, the heating curve advances in the upper, middle, and lower layers, and the maximum temperature rises, so the high temperature maintenance time becomes longer, and the amount of heat becomes excessive in the lower layer.

In addition, in order to eliminate such excess heat in the lower layer, the coke blending ratio in the upper layer was kept the same as in the conventional method, and in Comparative Example 3, where only the coke blending ratio in the lower layer was reduced, the lower layer became underheated.

However, in the method of the present invention, 300°C hot air is sucked in and sintered before ignition, so the heating curve advances in the upper layer and the maximum temperature reached increases, and the cooling curve remains the same as in the conventional method, so the high temperature The holding time is longer and the sintering reaction is sufficiently carried out, and since the amount of coke is reduced in the middle and lower layers, the high temperature holding time does not increase significantly, and the heat pattern in the upper, middle and lower layers is almost the same. The high temperature maintenance time is reached.

That is, in the method of the present invention, the upper, middle, and lower layers of the charge undergo almost the same thermal history, so that the quality is improved and sintered ore with extremely little variation can be obtained.

(3) The quality, production rate, product yield of sintered ore obtained as a result of testing regarding the production rate, coke consumption rate, quality, etc. of sintered ore,
Table 4 shows the coke consumption, falling strength, low temperature reduction powdering index, etc.
and are summarized in Figure 4.

From Table 4 and Figure 4, it is clear that when the sintering method according to the present invention is implemented, the sintering time is greatly shortened and the production rate is improved. The powdering index is also improved.

Of course, it can be seen that compared to the conventional method, the coke consumption rate of the example is significantly reduced.

Furthermore, results were obtained in which the total amount of NOx emissions was also reduced.

In addition, in the method of the present invention, the hot air suction temperature before ignition is 20
As a result of the first experiment, it has become clear that 0 to 400°C is appropriate, and even if the suction time is 3 minutes or more, no commensurate effect can be obtained.

As described above, according to the present invention, the air permeability is improved, which can shorten the sintering time and increase the production rate, and also improve the product yield and coke mixture in the lower layer of the sintering bed. By reducing the amount, the coke consumption rate can be significantly lowered.

In addition, the quality of sintered ore, as indicated by drop strength and low-temperature reduction powdering index, tends to improve.

In other words, the present invention improves various factors that are difficult to reconcile, such as increasing the production rate, significantly reducing the coke consumption rate, improving quality, and suppressing the amount of NOx generated, and its effects are extremely significant.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing the amount of combustion air suctioned during sintering, FIG. 3 is a heat pattern diagram, and FIG. 4 is a diagram showing the production rate according to the method of the present invention. Sintering time, product yield, coke consumption rate, falling strength, low temperature reduction powdering index,
FIG. 3 is a diagram showing the influence on total NOx emissions. 1.1': Mixed raw materials, 2.2': Hopper, 3, 3'
Nidrum feeder, 4: Sprocket, 5,5' varnish roving plate, 6: Ignition furnace, 7: Pallet, 8:
Charge (mixed raw materials), 9: Wind box, 10: Main duct, 11: Exhaust gas dust collector, 11': Dust remover, 1
2.12': Suction blower - 113: Crusher, 14: Hot screen, 15: Vibration supply feeder, 16: Cooler, 17: Exhaust stack, 18: Flow rate adjustment valve, 19: Hot air supply device, 20: Inlet pipe , 2L22: Conduit.

Claims (1)

[Claims] 1. A plurality of mixed raw materials mixed with different coke contents are fed onto a pallet so that the raw materials with low coke content are in the lower layer and the raw materials with high coke content are in the upper layer. A method for producing sintered ore, characterized in that only the upper layer of the charge on a packed pallet is dried and preheated, and then the upper layer of the charge is ignited and sintered. 2. In a Dwight Lloyd type sintering machine, multiple ore feeding devices are installed in the direction in which the pallets move to supply mixed raw materials onto the pallets, and a space between the last ore feeding device and the ignition furnace is installed. 1. A sintered ore manufacturing apparatus, characterized in that a hot air supply device is provided in the sintered ore production device, and the hot air supply device is configured to guide high-temperature gas discharged from a cooler of a sintering machine and/or a wind hox.