JPH06100917A - Method for direct reduction of iron-containing metal oxide - Google Patents

Abstract

PURPOSE: To provide an improved method to directly reduce iron containing metal oxide to a metal iron product.

CONSTITUTION: A direct reduction method of iron containing metal oxide, by which iron containing metal oxide is directly reduced to obtain a DRI metalized iron product, consists of a process to supply heavy oil to a decomposing region at the upstream side of a reduction reactor 10 under a condition controlled so as to form a decomposed product rich in CH₄ and successively, a process to directly supply the decomposed product to a reaction region 12, the reformed reduction gas rich in H₂ and CO by the reaction region 12 is formed and is brought in contact with an iron oxide material and by this means, the reduction of the iron oxide material is executed in the reaction region 12.

COPYRIGHT: (C)1994,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a direct reduction method of iron-containing metal oxides for directly reducing iron-containing metal oxides to metallized iron products.

[0002]

BACKGROUND OF THE INVENTION Direct reduction of iron oxide in the form of pellets or lumps of ores to solid metallic iron has become a commercial reality worldwide in recent years. The annual total capacity of direct reduction iron plants currently in operation or under construction exceeds 15,000 tons (metric) for direct reduced iron products, which are mainly used as feedstock in electric arc melting furnaces. Has been done. In order to meet the increasing demands of the world for such feedstock, an electric arc melting furnace has been additionally constructed, and the world demand for additional direct reduced iron has been high at a high rate for many years. It is clear that it will increase.

A known method for directly reducing iron oxide to metallic iron utilizes a reformed gas as a reducing agent. Natural gas is used as a raw material for producing reformed gas. The reformed gas used in the direct reduction method is produced by contacting natural gas with a substance containing oxygen in the presence of a catalyst (usually a nickel catalyst) in a unit called a reformer. It activates the quality reaction to produce a reformed gas rich in hydrogen H ₂ and carbon monoxide CO. The reformed gas collected from the reformer is then supplied to the reduction reactor containing the iron oxide material, and the reduction reactor directly performs the reduction reaction. Thus, the conventionally known direct reduction methods require two different reaction zones to carry out the actual direct reduction process. These conventional processes require treatment of the reformed gas product in the first zone to remove carbon dioxide CO ₂ and / or water vapor before entering the reduction zone.

[0004]

As mentioned above, natural gas is used as a source for producing reformed gas. Natural gas is a valuable natural resource with many uses,
The use of resources other than natural gas as a source to produce reformed gas would be of great benefit. In particular, it is extremely beneficial in that it is possible to use heavy oil which is easily available as a supply source for producing the reformed gas. Conventionally, the use of heavy oil in the above-mentioned known ordinary direct reduction method has been impractical because the sulfur present in the heavy oil reduces the power of the catalyst used in the reformer. As a result of the above, any conventional process using heavy oil requires treatment of the heavy oil in order to desulfurize it so as not to reduce the power of the catalyst used in the reformers of known direct reduction processes. To do.

Therefore, it is possible to use heavy oils having a high sulfur concentration as a source for producing the reformed gas used for the direct reduction of iron oxides to metallic iron, and iron-containing metals which do not require pretreatment of heavy oils. It would be highly desirable to provide a method for the direct reduction of oxides.

Accordingly, it is a primary object of the present invention to provide an improved process for the direct reduction of iron-containing metal oxides to metallic iron products.

A particular object of the present invention is to provide a method for the direct reduction of iron-containing metal oxides using heavy oil as a natural gas source for producing the reformed gas used in the direct reduction method.

Another object of the present invention is to provide a method for direct reduction of iron-containing metal oxide in which a gas is reformed and a metal oxide is directly reduced in a single reaction zone of a direct reduction reactor.

Still another object of the present invention is to use a DRI material as a catalyst for directly producing a reformed gas in a single reaction zone of a direct reduction reactor, the reformed gas contacting a metal oxide in the reaction zone. And to provide a direct reduction method of an iron-containing metal oxide for reducing a metal oxide to a metal iron product.

Other objects and advantages of the present invention will be made clear below.

[0011]

According to the present invention, the above objects and advantages are easily obtained.

The present invention is an improved iron-containing metal that directly reduces iron-containing metal oxides to metallized iron products using heavy oil as a source to produce reformed gas in the direct reduction of iron oxide particles. The present invention relates to a direct reduction method of oxides.

The method of direct reduction of iron-containing metal oxides according to the present invention comprises a single reaction zone comprising a bed of partially metallized iron oxide material and a direct reduced iron within the single reaction zone. (DRI or sea surface iron). The combustion chamber is provided immediately upstream of the single reaction zone. The heavy oil is atomized by the top gas recirculated from the reduction reactor so as to improve the combustion efficiency and supplied to the first region of the combustion chamber, where it is mixed with the preheated oxidant and is rich in oxygen. The body is formed. The mixture is then combusted under controlled temperature and time conditions to maximize the amount of natural gas (CH
A decomposed product containing ₄ ) is formed. The cracked product is then mixed with a portion of the top gas recycled from the reduction reactor by the second region of the combustion chamber, C
A reactor feed gas mixture consisting of H ₄ , CO ₂ and H ₂ is formed. The reactor feed gas mixture is then fed from the second zone of the combustion chamber to the single reaction zone of the reduction reactor under controlled temperature conditions, where there is direct reduced iron acting as a catalyst. React with the feed gas mixture to form a reformed reducing gas rich in H ₂ and CO in the reaction zone, the reformed gas contacts the iron oxide material in the reaction zone, and the iron oxide material is subjected to DRI. Reduce to a metallized iron product.

According to the invention, the reformed gas produced in the reaction zone is essentially 42-48% by volume H ₂ , 30-.
From 36% by volume CO, 2-4% by volume CO ₂ , 2-5% by volume CH ₄ , 10-16% by volume N ₂ , 2-5% by volume steam and 1-2% by volume SO _2. Composed, 0.05-
It has an oxidation degree of about 0.09 and a reduction ability of about 11 to 29. According to the direct reduction method of iron-containing metal oxides of the present invention, in order to provide sufficient energy to reform the feed gas, the feed gas mixture is subjected to a single reaction at a temperature of about 1000-1150 ° C. CH ₄ / of the supply gas supplied to the area
The ratio of CO ₂ + H ₂ O is preferably about 0.6: 1 to 0.7: 1. According to another characteristic of the process according to the invention, the activated heavy oil has a ratio of air to oxygen of about 7: 1 to 7: 2.
It is advisable to mix it with oxygen-rich air. Further, as mentioned above, the feed gas mixture fed to the single reaction zone at a controlled temperature should contain CH ₄ , CO ₂ and H ₂ O, preferably the mixture is based on 32 to 38
Volume% of H _2, 15 to 22 volume% of CO, 16 to 20 volume% of CO _2, 15 to 20% by volume of CH _4, 10 to 18 volume% of N _2, 4 to 8% by volume of water vapor, 2 ~ 4% by volume of C ₂
It is composed of H ₆ and 1 to 3% by volume of SO ₂ .

[0015]

In the direct reduction method of iron-containing metal oxide of the present invention,
Uses a single reaction zone of a direct reduction reactor for simultaneous formation of reformed gas for use in reduction processes and actual direct reduction of iron-containing oxidizing materials without the need for heavy oil pretreatment to desulfurize the heavy oil Heavy oil can be used as a source for producing the reformed gas. Therefore, the method of the present invention using heavy oil as a natural gas source for use in a simultaneous reforming / reduction process in a single reaction zone within a reduction reactor greatly improves the overall efficiency of previously known direct reduction processes. .

[0016]

EXAMPLE The present invention is an improved iron-containing metal that reduces iron-containing metal oxides directly to metallized iron products using heavy oil as a source to produce reformed gas in the direct reduction of iron oxide particles. The present invention relates to a direct reduction method of oxides.

With reference to FIG. 1, the apparatus used in the method of the present invention is a reduction reactor 10 having a combined single reaction zone 12 in which reformed gas is formed and reduction reactions are conducted simultaneously.
including. Above the single reaction zone 12 is a preheat zone 14 for preheating the iron-containing metal oxide to be reduced. The iron-containing metal oxide may be transferred from the storage container 16 to the residual heat area 14
Is supplied to. The DRI generated in the reforming / reduction reaction region 12 is cooled and discharged from the reduction reactor 10 via the outlet 18.

The top gas from the reduction reactor is removed therefrom via line 20 and introduced into wash zone 24, where the gas is cooled to remove reducing water. The top gas in the cleaning area 24 is also freed of solid particles that may be contained therein.

The iron-containing metal oxide introduced into the reactor may be in the form of pellets, for example about 63-68.
Contains iron by weight. DRI obtainable by the method of the invention
Is, for example, about 85 to 90% by weight of iron and 3 to 4% by weight.
Including carbon.

The top gas removed via line 20 has the following composition: That is, about 27 to 36% by volume of hydrogen, about 17 to 23% by volume of carbon monoxide, about 15 to 20% by volume of carbon dioxide, about 3 to 8% by volume of methane, about 14 to 20% by volume of nitrogen, about 12 to 20% by volume. % Of water vapor.

The temperature of the top gas exiting the reactor 10 is, for example, in the range of about 300 to 400 ° C. and is about 0.3.
It has an oxidation degree ηo of 3 to 0.38. Here, the degree of oxidation is the following "Equation 1"

[0022]

## EQU1 ## It is defined by CO ₂ + H ₂ O η ₀ = CO ₂ + H ₂ O + CO.

As described above, the top gas is washed in the cleaning area 24.
And cooled to a temperature of about 40-60 ° C, the moisture content of the top gas is reduced to a level of about 2-6% by volume.

The cooled and dewatered top gas is then split according to the invention into three streams. The first stream is conveyed to atomizer 30 via line 28 to activate heavy oil supplied to atomizer 30 via line 32. According to the method of the present invention, the flow rate of the top gas with respect to the heavy oil supplied to the atomizer 30 is about ³ to 4 NM ³ per liter of heavy oil. Typical heavy oils suitable for use in the method of the invention are:
API Baume degree of about 20 degrees or less and 66 ° C (15
It has a viscosity of about 100 centipoise or more at 0 ° F).

Another top gas flow is line 3
4 and is used as a heat source for the preheaters 36 and 38. The third stream, which is the majority of the top gas,
It is conveyed to the preheater 36 from there to the second region of the combustion chamber 44 for the following reasons.

According to the method of the present invention, the third stream of top gas is preheated in the preheater 36 to about 700-850 ° C, preferably about 750-800 ° C. The top gas is about 800 to 100 per ton of DRI in the reaction area.
It is supplied to the second region of the combustion chamber 44 at a flow rate of 0NM ³ .

The activated heavy oil is fed to the first region of the combustion chamber 44 where it is mixed with the oxidant to form an oxygen rich mixture. In accordance with the present invention, suitable oxidants have an oxygen O ₂ to air ratio of about 7: 1 to 7:
It is air containing a large amount of oxygen 2. The oxygen-enriched air is preferably preheated by preheater 38 and is supplied to the first region of the combustion chamber via line 46 at a temperature of about 700-800 ° C. The activated mixture of heavy oil and oxygen decomposes heavy hydrocarbons in about 0.2-1.0 seconds and is burned in the first zone at a temperature of about 1200-1400 ° C. A decomposed product rich in CH ₄ is formed.
Time and temperature of decomposition is controlled so as to obtain a degradation product having a maximum CH ₄ levels.

The CH ₄ -rich decomposed product is then fed to the second region of the combustion chamber, where essentially 3
_{2 to} 38% by volume H ₂ , 15 to 22% by volume CO, 16
20 volume% of CO _2, 15 to 20% by volume of CH _4, 10
To 18% by volume of N _2, 4 to 8% by volume of steam, it consists C ₂ H ₆ and 1-3 volume% of the SO ₂ in the 2-4% by volume,
And mixed with the top gas supplied from the preheater 36,
A feed gas mixture is formed that is at a temperature of about 1000-1150 ° C. The feed gas mixture is about 0.6: 0.7 CH.
_{It is characterized by 4} / (CO ₂ + H ₂ O) and a degree of oxidation of about 0.30 and 0.35. Then the feed gas mixture is DRI1
The DR supplied to the reforming / reduction zone 12 at a flow rate of 1000 to 1200 NM ³ per ton and heated in the reaction zone 12
Contact with I, which causes a reforming reaction, about 750
The reformed gas is formed by the following exothermic reaction that cools the reaction zone 12 to a temperature of ~ 850 ° C.

[0029]

[Number 2] _{CH 4 + CO 2 = 2H 2} + CO as described above, the reformed gas produced in the reforming reaction zone inside 12 has a temperature of about 750 to 850 ° C., basically, 42 48 volume% of H _2, 30 to 36 volume% of C
O, 2 to 4% by volume of CO _2, 2 to 5% by volume of CH _4, 10
To 16% by volume of N _2, 2 to 5% by volume of water vapor and 1-2
It is composed of volume% SO ₂ . The reformed gas is from 0.05 to
Oxidation degree of 0.09 and 11 to 2 represented by "Equation 3"
It is characterized by a reduction capacity of about 9.

[0030]

CO + H ₂ η = R CO ₂ + H ₂ O According to the method of the present invention, this reducing ability of the reformed gas results in an efficiency of 90-92% and a D containing about 3-4% carbon.
A high metallization product is obtained which gives an RI product. The sulfur content of the resulting product is similar to that obtained by the conventional DRI method using pure methane gas as the source for producing the reformed gas. The sulfur content of the heavy oil reacts in the reaction area to form SO ₂ and SO ₃ , and the top gas cleans the area 2.
The sulfur in heavy oil used in the process of the present invention does not diminish the ability of DRI as it is removed in 4 of the present invention.

[0031]

Therefore, according to the method of the present invention, the reformed gas is directly produced in the reforming / reducing zone 12 of the reduction reactor.
Using heavy oil as a source of H ₄ , it provides an efficient and effective method for direct reduction of iron-containing metal oxides to obtain DRI metallized iron products. The present invention may be embodied in other forms or carried out in other ways without departing from its spirit and basic characteristics. Therefore, the embodiment of the present invention is
In all respects, the scope of the claims should be considered as illustrative but not restrictive, and the scope of the claims embraces all such variations and equivalents.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus for carrying out the direct reduction method of iron-containing metal oxide of the present invention.

FIG. 2 is a schematic diagram of a combustion zone used in the direct reduction process of iron-containing metal oxides of the present invention to decompose heavy oil feedstock and form a gas mixture for a reduction reactor.

[Explanation of symbols]

10-reduction reactor, 12-single reaction zone,
14 ... Preheating area, 16 ... Storage container, 18 ... Outlet, 20 ... Line, 24 ... Cleaning unit, 2
8 ... Line, 30 ... Atomizer, 32 ... Line, 34 ... Line, 36 ... Preheater, 38 ...
Preheater, 40 ... Line, 44 ... Combustion chamber, 46
··line,

Front Page Continuation (72) Inventor Oscar Gee Dam Gee Venezuela Country 8015, Ed Bolivar, Putoldaz, Urban Los Saltos, Casa No. 7, Manz 12, Calle 4

Claims (12)

[Claims] 1. A reduction reactor is provided having a single reaction zone containing a bed of partially metallized iron oxide material and direct reduced iron (DRI) within the single reaction zone. A step of providing a combustion chamber immediately upstream of a single reaction zone, a step of activating heavy oil to maximize combustion efficiency, and supplying the activated heavy oil to the first zone of the combustion chamber Process and air preheated with heavy oil activated in the first area,
Mixing with oxygen and its mixture to form an oxygen-rich mixture, and burning the mixture under controlled temperature and time conditions to form a decomposed CH ₄ -rich product Mixing the decomposed product in the second region of the combustion chamber with the top gas from the reduction reactor to form a reactor feed gas mixture consisting of CH ₄ , CO ₂ and H ₂ O. Feeding the feed mixture into a single reaction zone, forming a reformed reducing gas rich in H ₂ and CO in the reaction zone, and reforming the iron oxide material in the reactor And a step of reducing the iron oxide material by bringing it into contact with gas to directly reduce the iron-containing metal oxide to obtain DRI metallized iron. 2. The method for direct reduction of iron-containing metal oxides according to claim 1, wherein the feed gas mixture fed to a single reaction zone is fed at a temperature of about 1000 to 1150 ° C. 3. CO ₂ and H ₂ O in the feed gas mixture.
The method for direct reduction of iron-containing metal oxides according to claim 1, wherein the ratio of CH ₄ to CH ₄ is about 0.6: 1 to 0.7: 1. 4. The method of direct reduction of iron-containing metal oxides according to claim 1, wherein the preheated air mixed with the activated heavy oil is preheated to a temperature of about 700-850 ° C. 5. The method for direct reduction of iron-containing metal oxides according to claim 1, wherein the top gas mixed with the decomposed product is preheated to a temperature of about 700 to 850 ° C. 6. The flow rate of the top gas to the heavy oil feedstock is
The method for direct reduction of iron-containing metal oxides according to claim 1, which is about 3-4 NM ³ / liter. 7. The method for direct reduction of iron-containing metal oxides according to claim 4, wherein air is rich in oxygen and the ratio of air to oxygen is about 7: 1 to 7: 2. 8. The direct flow of iron-containing metal oxide according to claim 1, wherein the flow rate of the feed gas mixture for direct reduced iron in a single reaction zone is about 1000-1200 NM ³ / ton DRI. Reduction method. 9. The reformed gas is basically 42-4
8% by volume H ₂ , 30-36% by volume CO, 2-4% by volume CO ₂ , 2-5% by volume CH ₄ , 10-16% by volume N ₂ , 2-5% by volume steam and The method for direct reduction of iron-containing metal oxides according to claim 1, which is composed of 1 to ₂ % by volume of SO ₂ . 10. The feed gas mixture is basically between 32 and
38% by volume H ₂ , 15-22% by volume CO, 16-2
0% by volume CO ₂ , 15-20% by volume CH ₄ , 10-1
8% by volume N ₂ , 4-8% by volume steam, 2-4% by volume
A method for direct reduction of iron-containing metal oxides according to claim 1, which is composed of C ₂ H ₆ and 1 to 3% by volume of SO ₂ . 11. The direct reduction method of iron-containing metal oxide according to claim 1, wherein the hydrocarbon is activated by a top gas recycled from the reduction reactor. 12. The reformed gas is about 0.05-0.0.
A method for direct reduction of iron-containing metal oxides according to claim 9 having an oxidation degree in the range of 9 and a reduction capacity of about 11-29.