JPS5950733B2 - Iron ore sintering method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for sintering iron ore used as a raw material for blast furnaces.

The condition that determines the quality and productivity of sintered ore for blast furnaces is the sintering reaction temperature in a sintering machine, and the optimum temperature varies depending on the raw material composition, but in current sintering machines, the combustion heat of coke, which is This is maintained by the amount of fuel coke that is evenly blended into the coke layer.

In this case, the sintering process progresses from the upper layer D to the lower layer E as the sintered raw material A advances from the charging side B to the extraction side C, as shown in FIG.

Therefore, the upper layer D is occupied by the thermally sintered ore that has completed sintering, and the lower layer E is occupied by the unsintered ore. This will be occupied by raw materials containing moisture and raw materials that are being preheated. Further, near the charging side B, the air H drawn from the upper layer D passes through the thin thermal sintering layer where the sintering of the upper layer D has been completed, and immediately reaches the sintering reaction layer.

Therefore, the excess air remains at a relatively low temperature and acts as combustion air for the coke, and the excess air, together with the coke combustion gas, becomes a drying and preheating source for the raw materials in the lower layer E, and itself becomes low-temperature exhaust gas for the sintering machine. It is emitted as exhaust gas. on the other hand,
The induced air near the extraction side C passes through the thick layer after sintering is completed and reaches the sintering reaction layer at a relatively high temperature. The difference in the amount of heat preheated and absorbed in the layers makes the amount of heat on the extraction side C in excess and surplus with respect to the charging side B, and the difference in amount of heat reaches 5 to 10% of the heat source unit of the sintering machine.

In reality, this difference is somewhat alleviated by the heat input to the ignition furnace and heat retention furnace on the charging side B.

Regarding air permeability, with the sintering reaction zone G as the border, the air resistance of the wet raw material layer and dry raw material layer on the charging side B is large, and the ventilation resistance on the extraction side C is large.
Since the ventilation resistance of the porous sintered layer is small, the extraction side C tends to have a bit of excess air, which means the sintering reaction temperature on the extraction side C tends to be slightly lower, and the difference in heat amount is alleviated, and the partial Even if it is not suitable in terms of performance, it is operated within an acceptable range on average, and productivity and quality are maintained at a certain level. However, the current pot yield of the sintering machine is 60-70%.
Although this includes the yield due to the unavoidable generation of fine particles due to methods such as the crushing process after the sintering machine, it is difficult to say that the pot yield is fully satisfactory.

This is because one of the main conditions for the quality of sintered mineral products is the strength of the finished product, and this strength is basically determined during the sintering reaction process of the sintered layer, and this strength affects the yield in the subsequent process. .
Therefore, it is thought that by making the current variation in sintering reaction temperature more uniform, the pot yield rate will further improve, and in turn, the heat loss will be reduced and the heat unit consumption will be reduced. In this invention, in order to improve product strength and pot yield and reduce heat consumption, sintering raw materials with evenly mixed coke are charged into a sintering machine and sintered from the charging side to the extraction side. In an iron ore sintering method in which the sintering raw material is sintered while moving the raw material, the necessary air that is attracted to the sintering raw material by the combustion heat of gas fuel or liquid fuel is charged into the sintering machine. The purpose is to correct the heat imbalance in the raw material charging and extraction directions in the sintering reaction zone by sequentially heating in a gradient manner, with more on the side and less on the extraction side.

Hereinafter, one embodiment of the present invention will be described based on FIG. 2. The sintering raw material is mainly made of granular iron ore, and granular coke necessary for heating and sintering is mixed therein, and fine particles are attached to larger particles and granulated to increase the permeability of the raw material layer. It is kneaded with a small amount of water added. Sintering raw materials are flatly charged from a charging hopper 12 of a sintering machine 1 onto a grade type conveyor pallet 3.

On the conveyor pallet 3, the coke in the upper layer of the sintering raw material 5 is ignited by the ignition gas burner 4 installed in the seventh position of the charging hopper 12, and the coke on the conveyor pallet 3 is ignited.
Combustion air is drawn from the upper layer to the lower layer of the sintering raw material 5 by the suction force of the exhaust gas fan 7 of the exhaust gas hopper 16, which is disposed below the sintering material 5. As the sintered raw material 5 advances toward the extraction side, the sintering process, that is, the drying, preheating, melting/sintering reaction of the sintered raw material 5 progresses from the upper layer to the lower layer, and the sintered raw material 5 is thermally sintered. The ore is extracted sequentially from the top of the conveyor pallet 3. The hot sintered ore extracted from the conveyor pallet 3 is coarsely crushed by a hot pulverizer 8, then sent to a cooler where it is cooled, and then passed through a cold crusher and a cold screen to be sized. It becomes a sintered mineral product for blast furnaces.

On the other hand, a heat retention hood 10 having a length extending from the ignition hood 9 to the vicinity of the extraction end is provided on the conveyor pallet 3, and the ceiling of the heat retention hood 10 has a plurality of heat retention hoods for supplying a correction amount of heat to the combustion air. Heating burners 1] are arranged at regular intervals from the raw material charging side to the extraction side, and air intake holes are equally spaced between each heating burner 11 so that air is evenly drawn into the raw material layer. 12 are provided.

Such a configuration allows heating of the combustion air by the combustion heat of the heating burner 11 of gas fuel or liquid fuel to be performed by the heat retention hood 1.
0, the amount is increased on the raw material charging side and less on the extraction side.

This means that during the process from charging the sintering raw material 5 with evenly mixed coke to the sintering machine 1 to extraction, the amount of heat for this sintering raw material 5 is insufficient on the raw material charging side of the sintering machine 1. In response to the excess on the extraction side, the excess or deficiency in the amount of heat is corrected. Therefore, the heat imbalance in the raw material charging/extracting direction in the sintering reaction zone can be kept small. If the hot air discharged from the cooler is used instead of the air drawn from the intake hole 12, the unit consumption of coke fuel can be reduced, and if it is used as combustion air for the heating burner, the fuel produced by the heating burner]1 can be reduced. Consumption can be reduced.

Although the gradient heat supply method using the heating burners 11 is based on the arrangement of the heating burners 11, it may also be based on the burner load capacity.

In the figure, 13 is an exhaust gas flow rate adjustment damper, 14 is a dust collection/exhaust gas treatment device, and 15 is an exhaust gas chimney. Note that some sintering machines are equipped with a heat retention furnace. The heat retention furnace is installed auxiliary after the ignition furnace because the surface layer of the sintered ore product at the initial stage of charging is rapidly cooled by contact with the atmosphere, making it difficult to obtain sufficient strength as a sintered ore product. As can be seen from the previous explanation, the reason why the surface layer does not have sufficient strength is that the amount of heat from the atmosphere attracted to the sintered layer is insufficient on the raw material charging side, and the temperature of the surface layer has not reached the appropriate temperature. This is the cause. In this method, the heat amount on the raw material charging side is set higher than the heat amount on the extraction side as a gradient heat supply method, so by accurately applying the appropriate amount of heat to the surface layer on the raw material charging side, the required strength of the finished product should be obtained. Therefore, the insulating furnace for the current purpose is unnecessary. As described above, according to the present invention, in order to suppress the heat disparity in the direction of raw material charging and extraction in the sintering reaction zone, it is possible to improve product strength and pot yield, as well as improve the heat loss, as can be seen from the explanation at the beginning. There is an advantage in reducing the heat consumption of the sintering machine by making it smaller.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a general sintering process model diagram, and Figure 2 is a configuration diagram showing one embodiment of the present invention.

Claims (1)

[Claims] 1. An iron ore sintering method in which a sintering raw material containing evenly mixed coke is charged into a sintering machine and sintered while moving the sintering raw material from the charging side to the extraction side. The combustion air for the sintering raw material is gradually heated in a gradient manner by the combustion heat of the liquid fuel, with more air being heated on the raw material charging side of the sintering machine and less air being heated on the extraction side of the sintering machine. A method of sintering iron ore.