JP2622483B2 - Quicklime production method in sintering machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a limestone powder which is stacked and charged on the top of a compounding material on a sintering machine pallet, calcined the limestone powder by the heat of an ignition furnace to form quicklime, and the obtained quicklime powder. And a recovery hood from the raw material sintered on the downstream side of the ignition furnace.

[0002]

2. Description of the Related Art FIG. 4 illustrates a sintering operation. The blended raw material 2 cut out from the feeder hopper 4 is laminated and supplied on the bedding ore cut out on the pallet 1 from the bedding hopper 3. The blended raw material 2 is ignited by the ignition device 15 and the coke breeze in the blended raw material is burned by the exhaust air of the main blower 14, and the blended raw material 2 is fired to become sintered ore. The sintered ore is pulverized by a pulverizer 5, cooled by a cooler 6, and then classified by a sieve 7. The product having a particle size of 8 to 16 mm on the sieve is returned to the bedding hopper 3 as bedding ore 10, and the remainder is transferred to the blast furnace as a sintered mineralized product 13. The classified particles having a particle size of -5 mm or less are mixed with the new raw material 12 by the mixer 8 as returned ore 11 and then returned to the feed hopper 4.

Generally, as a means for improving the air permeability of the blending material 2 on the pallet 1, a binder may be mixed into the blending material 2. As a binder, normal quicklime (Ca
O) is often used. Japanese Patent Application Laid-Open No. 58-133331 discloses a method for producing and utilizing this CaO at low cost. Limestone (CaCO ₃ ) powder 9 is cut out by a lime powder hopper 19 and laminated on the uppermost part of the compounding raw material 2.
A method has been proposed in which the lime powder is converted into quick lime (CaO) powder by the heat in 5 and recovered together with the ore return 11 by a sieve 7 and used as a binder.

However, in this method, (1) the sintered ore 13 and the ore 11 are not completely separated by the sieve 7, and a binder is mixed into the ore 13. (2) A part of the manufactured quicklime powder binder is scattered by the ventilation cooling in the cooler 6. There are problems such as.

Therefore, in Japanese Patent Application Laid-Open No. 1-147023, in order to improve the recovery yield of quicklime compared with the method of classifying by sieving, the specific gravity of the burnt quicklime is utilized by using a scraper, a blower or the like on a pallet. There has been proposed a method of absorbing and recovering the water. However, in this recovery method, the production of the sintered ore or the quick lime recovery equipment is greatly affected by the point at which the quick lime is absorbed and recovered in the longitudinal direction of the sintering machine, and is not stable.

For example, if the coke is recovered immediately after ignition, the coke has not yet completely burned or the quicklime is still at a high temperature, which adversely affects the recovery equipment. Further, when the ore is collected in the vicinity of the mining section, the ore must be fired while the quicklime powder is stacked in the upper layer between the mining section and the mining section. In that case, there is a problem in that the quicklime layer hinders the passage of air required for ore calcination, thereby reducing the production of sinter.

In Japanese Patent Application No. 3-54689, the temperature of the suction airflow to the suction hood is measured, and the suction hood is moved to a position where the measured temperature is within the target temperature range in the longitudinal direction of the sintering pallet. In addition, a method has been proposed in which quick lime powder is collected on a sintering pallet with a minimum residence time. However, according to this method, if the hot lime remains due to uneven scorching in the quicklime layer, the temperature of the suction airflow to the suction hood rises, so it is necessary to move the suction hood to the mining part side. Therefore, there is a problem that the residence time of the quicklime powder on the sintering pallet is prolonged.

[0008]

As described above, in the prior art, when scorching occurs in the quicklime layer, the recovery position moves in the direction of the mining section, and therefore,
The quicklime powder stays on the sintering pallet for a long time, which impairs the ventilation for sintering, and lowers the productivity of the sinter. An object of the present invention is to solve such a problem and to provide a method for producing quicklime in a sintering machine that suppresses the occurrence of scorching in the quicklime layer.

[0009]

The cause of the scorching in the layer of quicklime is the layer thickness disturbance due to the explosion of limestone after ignition. This explosion is a phenomenon in which, after ignition, CO ₂ gas decomposed inside relatively large particles in limestone powder blows off external quicklime. Once the thickness of the quicklime layer is disturbed, firing in a place where the layer thickness is large is delayed, and uneven burning occurs. Therefore, unevenness can be suppressed by smoothing the quicklime layer thickness immediately after the explosion occurs. The present invention has been made based on the above findings.

According to the present invention, limestone powder mixed with coke breeze is charged into the uppermost layer of raw materials on a sintering machine pallet, ignited in an ignition furnace to produce quicklime powder, and the produced quicklime powder is fired. The following method was applied to a method for producing quicklime in a sintering machine that sucks and collects from the machine. That is, while smoothing the disturbance of the raw material layer thickness due to the explosion of limestone powder after ignition, continuously measuring the temperature of the suction airflow at the suction and collection position of quicklime, moving the suction hood to a position where the measured temperature becomes a predetermined temperature. This is a method for producing quicklime with a sintering machine, wherein the quicklime is collected while being suctioned.

[0011]

According to the present invention, since the disturbance of the raw material layer thickness due to the explosion occurring after leaving the ignition furnace is smoothed and prevented before the collection of the quicklime powder, the uneven burning due to the disorder of the quicklime powder layer thickness is suppressed. be able to. In addition, since explosion marks occur most often immediately after ignition, it is effective to smooth them once on the exit side of the ignition furnace, and it is also necessary to smooth the explosion marks that occur later in the lower part of the quicklime layer. Therefore, it is preferable to provide at least two or more smoothing devices between the recovery device and the ignition furnace.

Since uneven burning can be suppressed in this way, it is possible to prevent a rise in the temperature of the suction airflow due to unburned residue, and to continuously measure the temperature of the suction airflow at the suction and recovery position of the quicklime to recover the quicklime. Since the suction and collection are performed immediately when the temperature reaches a level that does not hinder the equipment, the residence time of quicklime on the pallet can be minimized. That is, it is possible to minimize the hindrance to the passage of air (air required for calcination of the ore) by the quicklime. Therefore, it is possible to increase the layer thickness of the sintering raw material, and it is possible to reduce the basic unit of coke.

FIG. 1 is an explanatory view of an apparatus capable of suitably implementing the present invention. A limestone hopper 19 is installed between the mining hopper 4 and the ignition device 15. The limestone powder 9 and the coke breeze 18 are mixed and charged into the limestone hopper 19, and the limestone hopper 19 is layered on the compounding raw material 2 and cut out. Ignition is performed by the igniter 15, the coke breeze burns, and the limestone powder is thermally decomposed into quicklime (CaO).

A smoothing device 28 is provided immediately downstream of the ignition device 15.
Another set of smoothing devices 29 (in this example, cantilevered leveling plates) is installed at an interval further from the movable collection hood 21 at an interval. A thermometer 22 is attached near the tip of the heat-resistant hose 20 for suction and recovery connected to the movable collection hood 21, the temperature of the suction airflow by the collection hood 21 is measured, and the movable collection hood 21 is controlled via the controller 23. The pallet 1 is constantly moved in the longitudinal direction of the pallet 1 via the rail 24 to a position where the suction airflow reaches the target temperature. That is, while continuously measuring the temperature of the suction airflow with the thermometer 22 at the optimum position of the quick lime recovery on the pallet 1 which changes due to the change of the coke mixing ratio, the change of the ignition calorie of the ignition device 15, etc., the temperature becomes the optimum value. Mobile hood 2 on rail 24
1 to remove the quicklime on the blending material 2 and heat-resistant hose 20
, And sucked into the blower 26 to be collected in the hopper 25.

[0015]

[Example] Sinter production 6700-6900 (dry-
t / day), the amount of new raw material used (excluding coke, bedding ore, and returned ore) In a DL-type sintering machine with 7200 to 7500 (dry-t / day), the quicklime mixing ratio is 1.0% (based on the new raw material). ), And a conventional method (Japanese Patent Application No. 3-54689) was compared with the present invention on the premise of production of sintered ore (target CaO%: 9.5%). At this time, quicklime was produced on the uppermost layer of the sintering machine pallet under the following conditions and collected by suction. Table 1 shows the particle size distribution of the limestone, Table 2 shows the components of the limestone, and Table 3 shows the particle size distribution of the coke used.

Coke compounding ratio: 12.5% Layer thickness: 50 mm Limestone surface temperature by ignition device: 1100 ° C.

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

[Table 3] In the present invention, in order to recover the quicklime quickly, the target temperature of the suction airflow is set in the range of 85 to 105 ° C. Conventionally, the sintering machine was collected at a position 1/4 from the upstream side, so in this example, 1/20 (= 1
/ 4-1 / 5), the collecting position can be shifted to the upstream side.

As a result, the air permeability of the blended material layer after suction of quick lime is improved, and the layer thickness of the blended material can be increased in advance by that much. As a result, the sensible heat of the exhaust gas was used more effectively, and the basic unit of coke per ton of sintered ore could be reduced. Also, comparing the present invention with the conventional example,
As shown in FIGS. 2 and 3, the layer thickness can be increased by 5 mm, and the basic unit of coke can be reduced by 0.2 (kg / t-sinter).

[0021]

As described above, according to the present invention, suction and collection can be performed by setting the residence time of quicklime on the pallet to the minimum required time. Therefore, the gas permeability of the raw material layer after recovery is improved, and the thickness of the raw material layer can be increased in advance, and the basic unit of coke per ton of sintered ore can be reduced. As a result, the cost of the sintering process can be reduced as compared with the conventional method.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an apparatus capable of suitably implementing the present invention.

FIG. 2 is a graph showing the transition of the sintering raw material layer thickness and the basic unit of coke of the present invention.

FIG. 3 is a graph showing the transition of the sintering raw material layer thickness and the coke basic unit of the conventional example.

FIG. 4 is an explanatory view of a conventional sintering operation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pallet 2 Raw material 3 Bed hopper 4 Mineral feed hopper 5 Crusher 6 Cooler 7 Sieve 8 Mixer 9 Limestone powder + Coke coke 10 Bed litter 11 Returned ore 12 New raw material 13 Product 14 Blower 15 Ignition device 20 Heat resistant hose 21 Mobile Collection hood 22 Thermometer 23 Controller 24 Rail 25 Hopper 26 Blower 28 Smoothing device (front) 29 Smoothing device (back)

Claims (1)

(57) [Claims] 1. A limestone powder mixed with coke breeze is charged into the uppermost layer of raw materials on a sintering machine pallet, ignited in an ignition furnace to produce quicklime powder, and the produced quicklime powder is sintered. In a method for producing quicklime in a sintering machine that suctions and recovers from above, the turbulence of the raw material layer thickness due to explosion of limestone powder after ignition is smoothed, and the temperature of the suction airflow at the suction and recovery position of quicklime is continuously measured. A method for producing quick lime using a sintering machine, wherein a suction hood is moved to a position where a measurement temperature becomes a predetermined temperature while suction is collected.