JPS60248830A - Production of quicklime for binder by sintering machine - Google Patents

Abstract

PURPOSE:To produce efficiently quicklime as a raw material for sintered ore by utilizing the waste heat during production of the sintered ore in the stage of producing the sintered ore with a DL type sintering machine by using limestone as bedding ore on a pallet. CONSTITUTION:The limestone L sized to 5-10mm. is supplied from a bedding ore hopper 6 onto the pallet 7a as a bedding material in the stage of using the sintered ore to be used for a blast furnace in the DL type sintering machine 7. The sintering raw material R which consists of powder iron ore, coke powder, sinter returns, quicklime, etc. and is made into pseudo-particles is supplied in a laminar state onto said material and is sintered while the material is moved toward the right. The material is thus sintered. The sintering raw material is sintered by the downward suction ventilation by the wind box below the pallet and the limestone as the bedding ore is calcined to quicklime by the exhaust air generated in the stage of sintering at a high temp. The quicklime is separated together with the fine granular sinter returns of the sintered ore from the sintered ore and is used as the raw material for the sintered ore.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing quicklime, which is a binder for sintering raw materials, using a sintering machine at the same time as producing sintered ore in a sintered ore production plant.

[Conventional technology]

In a sintering operation, adding a binder (quicklime or slaked lime) to the sintering raw material increases the sintering production rate and increases the strength, so the amount of heat required during sintering can be reduced accordingly. In particular, quicklime has a large effect when added, as shown in Figures 3 and 4.
8°Mar, 1982).

However, quicklime is very expensive as an additive for sintered ore lime (approximately 3 to 4 times the price of limestone), which reduces the overall cost benefit.

Quicklime has traditionally been produced by placing limestone in a shaft furnace and firing it to cause a decomposition reaction. However, this would be expensive, so JP-A-52-71306 and JP-A-58
-31041, it is possible to use the firing heat of sintering to produce quicklime from inexpensive limestone in the process of sintering operation, return it to the sintering raw material, and use it to produce sintered ore in place of limestone. Proposed.

In JP-A-52-71306, when charging limestone into pallets, it is charged in layers on top of bedding ore, so it is necessary to separately install limestone charging equipment.
-31041, when charging by mixing with fuel in advance, there is a problem in that extra fuel is required. It has also been suggested that the supply be mixed with bedding ore, but in that case, the powder would be sucked into the wind box through the gaps between the pallet grate, making it impossible to achieve the purpose. Can not.

[Problem that the invention seeks to solve]

The purpose of the present invention is to provide a method that improves the drawbacks of the above-mentioned conventional methods. When producing sintered ore using a sintering machine, the waste heat is used to directly obtain quicklime from inexpensive limestone. is recycled into raw materials for sintering along with return ore.
In this case, the present invention provides a method that can be carried out efficiently without requiring separate equipment for supplying limestone to the sintering machine, using existing equipment, and without using extra fuel. .

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention is characterized in that when charging the sintering compound raw material into the balent, limestone is supplied as a bedding ore, and the sintering raw material is supplied on top of it for sintering. The gist of this article is a method for producing quicklime for binder using a sintering machine.

The present invention will be explained below with reference to the drawings.

The manufacturing process of quicklime for sintered binder in the present invention is schematically shown in FIGS. 1 and 2.

Limestone sized to a size of 5 to 10 mm is supplied to the bedding ore dumper 6. The limestone used in the present invention is one that has the property of being easily pulverized by crushing after a decomposition reaction.

On the other hand, a sintering raw material tank 1a, a coke tank 1b, a powdered limestone tank 1
Each raw material is supplied to conveyor 2.
The sintered raw material R is fed into a drum mixer 3, where water is added and adjusted, and then fed to the feed hopper 4 as a pseudo-particle sintered raw material R.

As shown in FIG. 2, while the pallet 7a is being moved in the direction of the arrow, limestone is first supplied from the bedding hopper 6, and the sintering raw material R is supplied thereon. The sintering raw material charged onto the pallet 7a is ignited by the igniter 5, and then moves from the upper layer by downward suction ventilation to cause a sintering reaction and is transferred to the ore discharge section of the sintering machine. reach. In this way, the entire sintering reaction is completed, and the sintered raw material on the pallet becomes sintered ore. The temperature of the exhaust gas sucked in the windbox is at room temperature in the ore supply side windbox, but increases as the sintering raw material sequentially moves to the ore discharge side, reaching a high temperature of 350°C to 450°C.

The temperature distribution in the cross section of the sintered layer inside the sintered cake during sintering is
As illustrated in the figure, approximately 125
It is 0°C to 1350°C.

As the sintered pallet progresses, the temperature of the limestone that is filled in the lowest part of the pallet increases, and as the sintered cake reaches the ore discharge area, the temperature rises as shown in Figure 6. As shown in the example of the temperature progression, the sintered cake directly above becomes red hot and a sintering reaction occurs as a sintered zone, so the temperature rises to a maximum of about 1000°C to 1100°C. That will happen.

Considering the decarburization and decomposition-resistant reaction of limestone, the following decomposition reaction Ca CO3+ Ca O+ CO2 ΔG'=40250-34.4T is calculated from the standard free energy change ΔG0≦0 at 1170°K (897°C) and above. It can happen in

Therefore, limestone can be decomposed into quicklime under conditions for producing sintered ore such that the bedding ore reaches a high temperature range sufficient for the decomposition reaction of limestone. The quicklime is transferred to the cooler 9 along with the sintered ore through the crusher 8, and the sensible heat is removed by the dust collector 11 and the wheeler 12 if the cooler has a sensible recovery facility by upward suction ventilation through the hood lO. is recovered as steam, and the sintered ore is cooled. In this way, in a state where quicklime and sintered ore are mixed, the next process of crushing and sifting is carried out at a
-5 mm is transferred to the return ore hopper as return ore, and is subjected to sintering together with other sintering raw materials. Quicklime is also mixed in this return ore.

On the other hand, there is almost no quicklime in +5 mm, and it is sent to the blast furnace as finished sintered ore.

゛In addition, the powdered quicklime collected together with other gases I and 2 by the dust collector 15 installed in the exhaust gas duct 14 and the crushing sieve equipment 18 and the dust collector 11 installed in the exhaust heat recovery duct 10 is After being collected by a suction-type dust collection vehicle such as a pneumatic dust collector or the like and stored in a hopper 21 exclusively for powder, it is used as a sintering raw material.

In this way, the quicklime produced by the sintering machine is of two types: small lumps mixed in the return ore and powdered lime mixed in the dust, which can be used instead of the conventionally used powdered limestone. be done.

〔Example〕

In a DL type sintering machine with a production capacity of 5000t/D, 30kg/1 of the 3mm powdered limestone that was conventionally used at 130kg/t-5inter.
The amount equivalent to sinter was replaced with limestone rectified to 10 to 5 mm, and this was supplied to Palento as bedding ore. The sintered ore with a diameter of 10 to 5 mm was turned into a finished product as it was, and due to the effect of quicklime, the production volume was 5000 tons/
The production amount of D increased to 5,700 t/D, and the coke consumption rate added to the sintering raw material increased to 45 kg/D.
43 kg/t-5 from t-5inter
decreased to inter.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to easily produce quicklime in the sinter manufacturing process, and since this quicklime is used, it not only increases production volume and reduces fuel costs, but also improves quality. It brings about various effects such as improved yield, improved NOx conversion rate, and is also effective in terms of pollution prevention.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing the overall process of the present invention, and FIG.
A detailed view of the sintering machine part, Figures 3 and 4 are graphs illustrating the influence of binder on production rate and drop strength, respectively, and Figure 5 is an example of temperature distribution over time in the sintered layer. FIG. 6 is a graph illustrating the temperature distribution of bedding ore. ■... Sintering raw material tank 2... Belt conveyor 3...
Drum mixer 4...Ore feeding hopper 5...Ignition device
6...Bedding hopper 7...Sintering machine 8...Crushing machine 9...Cooling machine 10...Hood 11...Dust collector 12...Boiler 13...Wind box 14...・Exhaust duct 15...Dust collector 16...Blower 18...Crushing and sieving equipment 19...Dust collector 20...Blower 21...Powder exclusive hopper lJj Applicant: Kawasaki Steel Co., Ltd. Patent Attorney Kazunori Saito Figures 3 to 4 Material Moisture (%)

Claims (1)

[Claims] ■ A method for producing quicklime for a binder using a sintering machine, which is characterized in that when charging the sintering raw material into a pallet, limestone is supplied as a bedding, and the sintering raw material is supplied on top of it and sintered.