JPS6144137A - Ferruginous conglomerated grain by product generated from direct reduction iron making mill - Google Patents

Abstract

PURPOSE:To obtain ferruginous conglomerated grains having substantial strength as an iron source by compounding cement with the powder dust generated in a reduction stage for ferruginous raw materials, pelletizing the mixture and curing and drying the conglomerated grains by means utilizing the waste gas of a reduction furnace. CONSTITUTION:The quicklime powder captured in a place where quicklime powder is generated is added to the sludge 3 captured by a dust collector 2 from the inside of the waste gas of the reduction furnace 1 and further the cement is added thereto; thereafter, the mixture is passed through a humidity controller 4 and is pelletized by a disk pelletizer 5. The pellets P1 are charged into a steam curing device 6 where the pellets are cured by the steam 10 generated by using part of the waste gas 7 from the reduction furnace as fuel and passed thereto from a steam generator 9. The cured pellets P2 are charged into a carbonization dryer 11. On the other hand, the gaseous CO2 7''' separated from the gas 7 by passing said gas through a CO2 remover 8 is added to the combustion gas of the generator 9 to form the gas 13 enriched with CO2 which is then passed through the dryer 11 and is brought into contact with the pellets P2. The pellets P2 are thus dried and hardened together with the carbonization of the lime component.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing iron-containing aggregate grains using direct reduction iron-making factory output, and more specifically, the present invention relates to a method for producing iron-containing agglomerated grains using direct reduction iron-making factory output, and more specifically, a method for removing CO2 from the reduction furnace exhaust gas of iron-containing raw materials and reducing it. Relating to a method for producing iron-containing nodules mainly from products generated in a direct reduction steel factory, such as iron-containing dust, quicklime dust, and gas generated from a reduction furnace, which have a process of reducing iron-containing raw materials that are recycled as gas. .

[Conventional technology]

Generally, in a steel factory, a wide variety of LFF1 type dust solids are generated during various manufacturing and processing steps within the factory, such as ore powder, sintered powder, cracked steel powder, rolling scale, and quicklime powder. On the other hand, a lot of hot gas is generated and discharged.

These generated solids are collected dry or wet to prevent environmental pollution and recover useful components contained, and most of them are granulated and reused. In addition, some of the generated gases utilize sensible heat having λ1,
Some are used as fuel.

[Problems to be Solved by the Invention] However, the use and treatment of useful dust generated in these factories and the use of discharged J gas are carried out in completely separate processing systems.

Further, even in direct reduction steel plants, a large amount of iron-containing dust is generated during the reduction process or steel manufacturing process, and reduction furnace gas is discharged during the reduction process.

A briquette method for the recovery and utilization of iron-containing dust from the above-mentioned direct reduction iron manufacturing plant was studied, and some binder was added to the iron-containing powder ore enriched with MeFe mixed with reduced iron powder generated during reduced iron production. For example, Japanese Patent Laid-Open No. 55-115930 discloses a method of treating ore, which involves kneading at a controlled humidity and then pressurizing, followed by curing and hardening.
Although it is described in the publication, JP-A-55-115930
The description in the publication is only for the treatment of 4'y)-like solids, and the use of other products generated within the factory, ie, the gas generated from the main furnace, is not equally considered.

CO and c from direct reduction steel plants in general and reduction furnaces in particular
The generated gas containing O2 is removed from COZ f& and blown into the reduction furnace again to be used as reducing gas, but the removed CO2 is dissipated and is not used.

Some of the present inventors developed an efficient method for treating iron-containing dust in steel factories, especially direct reduction steel factories, and
No. 8-183899 and Japanese Patent Application No. 183902/1982, the present inventors have further proposed a method for treating dust solids containing useful components such as iron-containing dust and quicklime powder, which are generated in direct reduction iron manufacturing plants. Focusing on the reduction furnace gas containing CO2 and C02 components generated and discharged in the reduction process of reduction iron manufacturing, and the CO2 gas that is separated and destroyed in order to recycle it to the main furnace, we will analyze these gases generated in the same factory. Various studies are being conducted on an economical method for producing iron-containing nodules that have sufficient strength to withstand use as an iron source using a binder with a low tensile force by rationally combining useful dust solids, exhaust gas, and emitted CO gas. This completes the present invention.

[Means for solving problems]

The present invention removes CO2 from the reduction furnace exhaust gas, which is a ferrous raw material, and uses it as a reducing gas.
There is a granulation process in which a small amount of cement is mixed with dust and quicklime dust, and this is granulated into nodule granules, and unremoved CO2 from the reduction furnace is separated and used as fuel to produce water stalks for curing and hardening. At the same time, CO2 gas separated from the reduction furnace exhaust gas is combined with this combustion gas to obtain a gas for carbonation, hardening and drying. iron-containing aggregate grains produced from a direct reduction iron-making factory, characterized by comprising a primary hardening step in which the hardened grains are carbonated with the CO2a combined combustion gas and dried at the same time. This relates to a manufacturing method.

The present invention will be described in detail below.

At the direct production + M iron factory, the preparation process of iron-containing raw materials such as ore, the loading process of iron-containing powder raw materials, '! At1.1
A large amount of iron-containing dust is generated during the manufacturing process, rolling process, etc., and these dusts are collected by dry or wet means to prevent environmental pollution and to be reused as an iron source.

Also, in steel factories, a large amount of quicklime, which is used as an auxiliary raw material, is produced in-house or purchased.

A part of this quicklime becomes dust and is collected in the steel factory equipment such as manufacturing equipment such as firing kilns, crushing equipment, or handling equipment such as storage and general transportation, and a part of it is effectively used. It is done. These iron-containing dusts have particle sizes and components as shown in Table 1, for example.

Table 1 These iron-containing powders and quicklime powders have different particle sizes depending on where they are generated, so in the present invention, it is preferable to adjust the particle size to be suitable for granulation means such as pellets or Brikent. For example, when pelletizing by a transfer means such as a polling disk or a polling drum, the particle size is 4.
It is preferable to set the grain size between 11 and 45 μm so that 65% or more is 5 μm or less, and the lower fine grain is 65910.
If it is below, the transfer granulation efficiency will deteriorate.

On the other hand, when briquette granulation is performed by pressure molding means, relatively coarse powder with a maximum particle size of 51 or less is added to the collected dust having a particle size as shown in Table 1 in order to provide appropriate air permeability. It is preferable.

In the present invention, direct reduction′! The above-mentioned iron-containing powder and quicklime powder generated within the A iron factory are used as granulation raw materials by adjusting the particle size as necessary, but in addition to this, powdered raw materials supplied from outside the factory are used as necessary. It can also be added.

A granulated raw material consisting of iron-containing powder and quicklime powder prepared mainly from powder raw materials generated in a direct reduction steel factory as described above,
Add cement as a binding agent.

The amount of cement added should be determined depending on the amount of quicklime contained in the granulation raw material and the granulation method,
When the quicklime content is low, it is increased, and when the content is high, it is decreased, but it is preferable to add the amount in the range of 2 to 10%.

If the amount of cement added is less than 2%, the lime content will substantially bind and harden, making it impossible to obtain the necessary granulation strength, while if it is more than 10%, the strength will be excessive, which is uneconomical.

As described above, the raw material for granulation, which is made of iron-containing material with the necessary binder added and powder generated in the factory, can be granulated as desired by granulation methods such as transfer granulation, pressure molding granulation, or extrusion granulation. The moisture content is adjusted to the selected amount and kneaded.

The moisture-adjusted and kneaded granulated raw material is granulated into cold pellets or burritos by any granulating means such as a transfer granulating device such as a polling disk or a polling drum, or a pressure forming device such as a twin-wheel briquette machine. be done.

Next, this granulated material is subjected to a primary hardening treatment by steam curing, and furthermore, a hardening treatment agent such as steam and CO2 gas used in a secondary hardening treatment by carbonation, and furthermore, a hardening treatment agent such as steam and CO2 gas used in a secondary hardening treatment by carbonation, and further a hardening treatment of the cured product. The most characteristic feature is that the drying gas used for drying is supplied from a reduction furnace for iron-containing raw materials.

The composition of the reduction furnace exhaust gas described above generally contains many combustible and reducible components as well as considerable amounts of CO and CO2 components, as illustrated in Table 2.

In the reduced steel mills shown in Table 2, after the CO2 gas contained in the reducing furnace exhaust gas is separated and diffused, the remaining gas is recycled to the reducing furnace as a reducing gas.

This reduction furnace exhaust gas has a relatively high exothermic value,
It also has a quantity of heat.

In the present invention, the characteristics of the above-mentioned head furnace exhaust gas and the CO separated from the head furnace exhaust gas.

This is a closed system method for processing nodules generated in the factory, which focuses on gas and uses it to harden the nodules.

That is, in the present invention, a part of the reducing furnace exhaust gas is separated before the CO2 gas is removed and used as a fuel to produce the steam for curing the nodules described above and to obtain high-humidity combustion gas.

The produced steam is introduced into the nodules curing tank to adjust the atmosphere for the primary hardening treatment of the nodule grains through water stalk air curing.

The above-mentioned steam curing in the present invention is carried out under normal conditions, for example, at a temperature of 100°C or less, preferably 70 to 80°C, after a humidity of 100% is adjusted by water vapor.

The nodules that have been primarily hardened by water stem air curing are then
The main component is 002 gas, which is separated from the above-mentioned reduction furnace exhaust gas and has a composition as shown in Table 4, in the combustion gas having the composition shown in Table 3 which is emitted during the production of the curing steam. CO2 10%~30
% C02 enriched gas and heated it to 150°C.
It is carbonated and dried by contacting with CO2 enriched gas adjusted to a temperature of ~250°C.

Table 3 Table 4 In the above-mentioned carbonation drying, the nodules are brought into contact with carbon dioxide gas enriched gas, and the lime contained therein is carbonated by 002 in the gas, resulting in CaCO3.5i
02 and CaCO3 and is dried.

Thus, the primary hardened particles are further hardened by the carbonation drying treatment described above.

As described above, the present invention aims to recycle particulate dust generated within a factory by accurately grasping the characteristics of each of the materials generated within the same factory, eliminating waste, and effectively combining and utilizing the waste. This is an extremely useful method of recycling waste generated in factories, which is economical and has the effect of improving the environment.

(Example) Hereinafter, an example of the present invention will be further described with reference to the flowchart shown in FIG.

The mixture of the under-sieve powder of ore pellets and throat charged into the reduction furnace (11) and the reduction furnace dust collection slurry (3) collected from the exhaust gas of the reduction furnace (1) by the dust collector (2) is further shown in the figure. 3% (by weight) of quicklime powder collected at places where quicklime powder is generated, such as unused quicklime storage potspur, was added and used as a granulation raw material.The particle size structure of these granulation raw materials is shown in Table 5. .

Table 5 8% cement as a binder in these blended raw materials
While adding and mixing, the moisture content was adjusted to 9% using a mixing and humidity control device (4).

This adjusted granulation raw material was transferred and granulated using a disk granulator (5) to obtain pellets (Pl) having a particle size of 5 to 101 times.

Next, this pellet (Pt) was placed in a steam curing device (6
), and part of the reduction furnace exhaust gas (7) is removed from CO for recycling (7') to the reduction furnace (1).
2 device (8), and this fractionated gas (7
Water stalk gas from water stalk gas generator τ(9) using fuel as fuel
0) to the steam curing device (6), and the humidity was 100.
%, water stalks were air-cured for 10 hours at a temperature of 80°C to obtain Enyu pellets P2.

Next, this cured pellet P2 was passed through a carbonation dryer (1
1). On the other hand, the combustion gas (12) at a temperature of 300°C discharged from the steam generator (9) is deco
C separated from the reduction furnace exhaust gas (7) in the second device (8)
02 gas (7~) was added to obtain 002 enriched gas (13) having the composition shown in Table 6 at a temperature of 200°C.

Table 6 This C02 enriched gas is passed through the carbonation drying device (11) and kept in sufficient contact with the steam-cured pellets (P2) for 3 hours to remove the lime contained in the pellets (P2). The pellets were dried as well as carbonated for a minute.

The thus obtained carbonated dry pellet y l (P3) is
Pressure strength 1□ despite the small cement content
The weight was 160 kg/pellet.

〔Effect of the invention〕

In this way, in the present invention, the useful dust solids and exhaust gas directly generated at the Tongyuan factory are used as an iron source by rationally combining them (this is used as an iron-containing material with sufficient strength). Agglomerates can be produced economically.

[Brief explanation of drawings]

The figure is a flowchart showing an example of implementation of the present invention. (1) Reduction furnace (2) Dust collector (3) Reduction furnace dust collection slurry (4) Mixing 8I? a Humidification device (5) Disk granulation device (6) Steam generator (7) Reduction furnace exhaust gas
(7゛) Recycling (7'') Preparation gas (7'
) COZ gas (8) CO2 removal equipment (9) Steam generator 00) Steam (11) Carbonation drying equipment (12) Combustion gas

Claims (1)

[Claims] 1. In a direct reduction steelmaking factory that has a process for reducing ferrous raw materials that removes CO_2 from the reduction furnace exhaust gas from ferrous raw materials and recycles it as reducing gas, a small amount of cement is mixed with the ferrous dust and quicklime dust that is generated. A granulation step of granulating into nodules, a separation of the unremoved CO_2 exhaust gas from the reduction furnace, and using this as fuel to obtain steam, and adding CO separated from the reduction furnace exhaust gas to this combustion gas.
A process for producing a gas for hardening the nodules by mixing the _2 gases to obtain a dry gas, a primary curing process for curing the nodules using the water vapor, and further carbonating the lime content of the hardened particles using the CO_2 mixed combustion gas. 1. A method for producing iron-containing nodules using direct reduction ironmaking factory output, comprising a secondary hardening and drying step.