JPS62238310A - Production of reduced iron - Google Patents

Abstract

PURPOSE:To decrease the quantity of the heat to be supplied from the outside of the system and to reduce cost by withdrawing part of a fluid medium from the 2nd reduction furnace to reduce preliminarily reduced iron to metallic iron, separating carbonated lime therefrom and charging the same into the 1st reduction furnace. CONSTITUTION:The preliminarily reduced iron from the 1st reduction furnace as well as reducing gas and CaO are charged into the 2nd reduction furnace 2. Part of the fluid medium is withdrawn from the furnace and is magnetically separated to reduced iron and carbonated lime by a separator 5. The carbonated lime is charged together with iron ore, 2nd reduction furnace exhaust gas and oxygen into the 1st reduction furnace 1, by which the preliminary reduction of the iron ore, the regeneration of CaO of the carbonated lime and the replenishment of CaO by the supply of limestone are executed. The preliminarily reduced iron formed in such a manner is charged into the 2nd reduction furnace 2. The rate of utilization of the reducing gas is improved and the sulfur-component in the preliminarily reduced iron is decreased by the above-mentioned method.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uses CaO as a gravel medium, reduces or eliminates the amount of heat supplied from outside the yarn, and furthermore, uses CaO as a carbonated material. The present invention relates to a method for producing reduced iron that does not require a separate regeneration furnace for regenerating lime into CaO.

[Conventional technology]

In a device that reduces pre-reduced iron with reducing gas in the flow VJ layer, the conventional method for replenishing the thermal energy necessary for reducing the pre-reduced raw iron is to reduce the reducing gas introduced into the second reduction furnace before the introduction of the reduction furnace. Then, the gas was introduced into a separate heating furnace, heated to a high temperature by indirect heating in the heating furnace, and then introduced into a reduction furnace.

In addition, in a device that processes coal and iron ore in the same fluidized bed furnace to gasify coal gold and reduce pre-reduced iron using the gas, it is essential for reducing pre-reduced iron and gasifying E-1 coal. - (The conventional method of replenishing energy is one person who uses the heat of combustion of coal.) One person who uses the heating of f carrier 4 stands etc. is known, tl,.

(Problems that #i is trying to solve) However, with the method of the qiffer, the Chicoop performance of the gas heating furnace is -42, the heating temperature is limited to about 1000°C, and the amount of heat that is cheap for reduction is f+11. In order to achieve this, it was necessary to heat a larger amount of reducing gas than the stoichiometric amount of reducing gas used in the reduction reaction.Therefore, the gas heating furnace equipment had to be quite large in terms of capacity, and Since a large amount of fuel is required for its operation, it is extremely disadvantageous in terms of equipment costs and operating costs.

Furthermore, in the method of using the combustion heat of Mugiya's coal, in order to replenish the amount of heat required for the reaction, it is necessary to burn mass-produced coal, which is stoichiometrically used for the reduction reaction, resulting in a high unit consumption rate. In addition, in the method of utilizing the sensible heat of heat carrier particles, it is necessary to circulate a large amount of heat carrier particles between the reduction furnace and the heat carrier particle reheating furnace in order to replenish the amount of heat required for the reaction, which requires a large amount of equipment. There are problems such as being large-scale and uneconomical.

In order to solve the above problems, the inventors have already developed a method in which the carbonation reaction of CaO is used to replenish thermal energy for the reaction in the second reduction furnace.

In this method, the carbonated lime produced in the second reduction furnace is sequentially extracted from the second reduction furnace, heated and regenerated, and the Ca
O and is circulated again to the No. 2a main furnace, and a regeneration furnace is installed separately from the second reduction furnace for heating and regeneration.

However, when a separate regeneration furnace is provided, the regeneration furnace itself requires additional equipment such as ventilation equipment, coal supply equipment, exhaust gas treatment equipment, etc., and there is a problem in that the equipment becomes expensive.

The present invention has been made in view of the above points, and aims to provide a method for manufacturing reduced iron that can reduce or eliminate the amount of heat supplied from outside the thread, and that solves the above four points. be.

[Means and actions to solve all problems] First step in this field
The method of the invention will be described with reference to FIG. The pre-reduced iron is supplied to the second reduction reactor 2 together with particles mainly composed of caof, and at the same time, reducing gas is supplied from the lower part of the second enshrine reactor 2 to form a fluidized bed. Carbonation reaction of CaO inside the fluidized bed 4 of the furnace 2 (CaO+ Co2 → CaC○3)
to supply the thermal energy necessary for the reduction of the pre-reduced iron and reduce the pre-reduced iron to metallic iron.Meanwhile, a part of the fluid medium is extracted and the reduced iron and charcoal atomized lime and After separation, the carbonated lime is charged into the =GL Enja furnace 1, and at the same time, the exhaust gas from the second reduction furnace 2 is supplied to the lower part of the first reduction furnace 1 to form a flow IJJ layer 3. , heat and regenerate the carbonated lime inside the flow @ layer 3 of the first reduction furnace 1 to make CaO, and use the iron ore as pre-reduced iron,
It is characterized in that particles containing CaOf as a main component are anchored together with pre-reduced iron in the second reduction furnace 2 and used again.

In the method of the first invention, the second method is to separate a part of the fluidized medium extracted from the former furnace 2 into reduced iron and carbonated lime using a separator 5 such as a non-magnetic type 4 separator. Carbonated lime is placed in the first reduction furnace by four people, and is regenerated into CaO in the fluidized bed 3 that pre-reduces iron ore, which is then circulated together with the pre-reduced iron to the second Sakamoto furnace 2 for use. do. 6
is a cyclone, 7 is an exhaust gas treatment device, 8 is a supplementary limestone supply officer, and IO is an oxygen or air supply department.

Further, the method of the second invention of the present application, which will be explained with reference to FIG. Preliminary reduced iron from the first reduction furnace 1 is supplied to the second reduction furnace 2 together with particles mainly composed of Cao, and coal is supplied to the 2m main furnace, and at the same time oxygen or oxygen gas is supplied from the lower part of the 2a main furnace. Steam is supplied to form a fluidized bed 4, and a carbonation reaction of CaO (cao+c○2→CaC○3) occurs inside the fluidized bed 4 of the second reduction furnace 2.
(4) Q After separating into those whose main components are carbonated lime, char, and coal ash, the materials whose main components are carbonated lime, char, and coal ash are transferred to the first reduction furnace. l
At the same time, the exhaust gas from the second reduction furnace 2 is supplied to the lower part of the first reduction furnace 1 to completely form the fluidized bed 3, and the first reduction furnace 1
The carbonated lime inside the fluidized bed 3 is heated and regenerated to produce C.
In addition to aO, iron ore is used as pre-reduced iron, and CaO
The particles mainly composed of
It is characterized by being recycled and used.

In the method of the second invention, a part of the fluidized medium extracted from the second reduction furnace 2 is separated using a magnetic separation type separator or the like. !
5, the reduced iron and the one mainly composed of carbonated lime, chia V-, and coal ash are divided into two parts. 1 return =
1, heated and regenerated in the stream @ layer 3 for pre-reduction of iron ore to form CaO, and then transferred to the second reduction furnace 2 together with pre-reduced iron for use.

Regardless of the method 2 of the invention described above, the flue gas discharged from the first reduction furnace 1 and dust removed by the cyclone 6 contains a large amount of sensible heat, and that heat is used for preheating the raw material, etc. It is possible to use energy, and Co,
Since it has a large amount of useful components such as H2 remaining, it can be used as fuel as it is, or after exhaust gas treatment, used as a raw material for chemical synthesis, or recycled as gas introduced into the second reduction furnace 2. It is also possible to do so.

〔Example〕 Examples of the present invention will be described below.

Example 1 According to the flow shown in FIG.
: 35%, H2O: 3%, CO: 57%, co, : 5%
of reducing gas at 25°C, 122 L, 2 Nrd/h
, quicklime (CaO) was heated at 1100°C to 364.0 k (
J/h, and the second reduction furnace 2 was heated to 900'C.

I drove at 5kQ/c Ura G.

On the other hand, from the fluidized medium, 9/h was extracted at 1649.6, and reduced iron and carbonated lime were separated using a magnetic I4 type machine 5, and then the carbonated lime was transferred to the first reducing furnace. I went to ■. In addition to the above-mentioned carbonated lime, iron ore was added to the first reduction furnace 1 at 25'C to 1429.7g/P'L.
Composition is H2: 28.4%, H2O: 14.7%, CO
: 38.8%, Co2: 18°1% second reduction furnace exhaust gas (1075.1π/11'l at H900'C, oxygen 2
149.4 Nnt'/h was charged at 5°C, and the first reduction furnace 1 was operated at 1100°C and 9/dG. In the first reduction furnace, iron ore is pre-reduced, carbonated lime is
After O regeneration and CaO replenishment by limestone supply, 9/hSCaO364,0/ is added to the generated preliminary reduced iron 1286.5.
c9/l, both were charged into the second reduction furnace 2 at 1100'C. As a result, a reduced iron product of 1000 A:g,/'h was extracted. Further, the exhaust gas discharged from the first reduction furnace 1 was 1221.2 Ny&/h, and its composition was as follows.

H24.8% H2OH, 2% CO13.5% Co248.5% Example 2 According to the flow shown in Fig. 2, pre-reduced iron was supplied to the second reduction furnace 2 at 1100'c at 1286.5#/h, coal 25
428.8 in °C! //'h, oxygen at 25°C 1.
37.8 Nm'/'rl, steam at aOOoC 5
5kg/h, quicklime (Car) at 1100°C for 20
6/cq//h and heated the second reduction furnace 2 to 900°C15
I drove at kg/c4G.

On the other hand, among stream #J media, 1446. o#/h is extracted and separated into reduced iron and carbonated lime in a magnetic separation type separation tank 5.
After separating the product mainly composed of char and coal ash, the product mainly composed of carbonated lime, char and coal ash was introduced into the first reduction furnace 1. To the first reduction furnace, 1429.7 kg/h of iron ore with a composition of H2:25.6% was placed at 25°C in a pond containing carbonated lime, char, and coal ash as main components. , H2C: 13.8%, CO: 4
1.7%, CO2F 19.4% second reduction furnace exhaust gas
684.1 N go/h at 00°C, 11 N at 25°C
0.5Nd/h was charged, and the first reduction furnace was heated to 1100'c.
It was operated at 5 kg/dG. In the first reduction furnace, preliminary reduction of iron ore, CaO regeneration of carbonated lime, and supply of CaO by limestone are carried out.
286.5kg/h, CaO200k? AI was charged into the second reduction furnace 2 at 1100'C. As a result, 9/h was extracted for 1000 reduced iron products. 'I
:The amount of exhaust gas discharged from the first reduction furnace 1 was 819.
3 Nnl/”n, and moreover, the formation was like Tsuza.

I (24,0% H2C28.5% Co 14.2% Co253.8% 〔Effect of the invention〕 The first invention of the present application has the following effects.

(1) The thermal energy required for the reduction reaction is converted into CaO and C.
Since it can be replenished through an exothermic reaction with O2, it is possible to reduce or eliminate the amount of heat supplied by external heating.

(2) Since CO2, which lowers the reducing gas utilization rate, can be removed in the fluidized bed, the reducing gas utilization rate can be improved and the amount of reducing gas required for reduction can be reduced.

(3) The sulfur content contained in the pre-reduced iron is reduced to 1 in the form of CaS.
Because it can be used as a waste, not only can the sulfur content in the reduced iron product be lowered, but special desulfurization equipment is not required when exhaust gas is recycled.

(4) By heating and regenerating the carbonated lime in the first reduction furnace, there is no need to provide separate regeneration furnace equipment;
Set 1Iil! Not only can costs be reduced, but the expenses necessary for operation can also be reduced.

Further, the second invention of the present application has the following effects.

(1) It is possible to gasify coal at the same time as reducing pre-reduced iron.

(2) Since the CO2 and H2C generated by the reduction of pre-reduced iron with Co and H2 can be converted back into CO1H2 by the coal coexisting in the fluidized bed, the basic unit can be reduced.

(3) Since the thermal energy required for reducing gas generation and reduction reaction can be supplied by the exothermic reaction between CaO and CO2, the unit consumption can be reduced.

(4) Since CO2, which lowers the reducing gas utilization rate, can be removed in the fluidized bed, the reducing gas utilization rate can be improved and the basic unit can be lowered.

(5) Since the sulfur content contained in coal and pre-reduced iron can be removed in the form of CaS, it is not only possible to lower the sulfur content in the product reduced iron, but also to use special desulfurization when recycling exhaust gas. No equipment required.

(6) Since pre-reduced iron, char, and quicklime can be fluidized in a coexisting state, sintering of metallic iron, which is a +n1 problem in high-temperature gas reduction, can be prevented.

(7) By heating and regenerating carbonated lime in the first reduction furnace, there is no need to separately provide regeneration furnace equipment;
Not only can equipment costs be reduced, but the costs necessary for operation can also be reduced.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of an apparatus for carrying out the method for producing reduced iron of the present invention, and FIG. 2 is an explanatory diagram showing another example of the present invention. 1... First reduction furnace, 2... Second reduction furnace, 3.4...
・Fluidized bed, 5...minutes 4iso, 6...cyclone, 7.
...Exhaust gas treatment device, 8...Supplementary limestone supply pipe, 10
...Oxygen or air supply pipe

Claims (1)

[Claims] 1. A method in which iron ore is pre-reduced in a first reduction furnace and reduced to metallic iron in a second reduction furnace, in which the pre-reduced iron from the first reduction furnace is combined with particles containing CaO as a main component. At the same time, a reducing gas is supplied from the lower part of the second reducing furnace to form a fluidized bed, and the carbonation reaction of CaO proceeds inside the fluidized bed of the second reducing furnace to produce pre-reduced iron. While replenishing the thermal energy necessary for reduction, the pre-reduced iron is reduced to metallic iron, while a part of the fluidized medium is extracted and separated into reduced iron and carbonated lime, and then carbonated lime is The first
At the same time, the exhaust gas from the second reduction furnace is transferred to the first reduction furnace.
CaO is supplied to the lower part of the reduction furnace to form a fluidized bed, and the carbonated lime is heated and regenerated inside the fluidized bed of the first reduction furnace.
A method for producing reduced iron, characterized in that iron ore is used as pre-reduced iron, and particles containing CaO as a main component are circulated together with the pre-reduced iron to a second reduction furnace for use. 2 In a method in which iron ore is pre-reduced in a first reduction furnace and reduced to metallic iron in a second reduction furnace, the pre-reduced iron from the first reduction furnace is supplied to the second reduction furnace together with particles whose main component is CaO. Then, coal is supplied to the second reduction furnace, and at the same time, oxygen or oxygen/steam is supplied from the lower part of the second reduction furnace to form a fluidized bed, and the carbonation reaction of CaO is carried out inside the fluidized bed of the second reduction furnace. In addition to replenishing the thermal energy necessary for reducing the pre-reduced iron and gasifying coal, the pre-reduced iron is reduced to metallic iron, while a part of the fluid medium is extracted and the reduced iron and carbonated After separating the carbonated lime, char, and coal ash into those whose main components are carbonated lime, char, and coal ash, the carbonated lime, char, and coal ash are charged into the first reduction furnace, and at the same time into the second reduction furnace. The exhaust gas is supplied to the lower part of the first reduction furnace to form a fluidized bed, and the carbonated lime inside the fluidized bed of the first reduction furnace is heated and regenerated into CaO, and the iron ore is pre-reduced. A method for producing reduced iron, characterized in that particles containing iron and CaO as a main component are circulated and used in a second reduction furnace together with preliminary reduced iron.