CN106011357A - Hydrogen plasma smelting reduction iron making method and system - Google Patents

Abstract

The invention discloses a method and a system for making iron by hydrogen plasma smelting reduction. The method comprises the following steps: putting hydrogen and argon mixed gas into a plasma spraying gun, ionizing the hydrogen and argon mixed gas into plasmas under the action of high-frequency voltage and electric arc, and spraying the plasmas from a nozzle, to form high-temperature plasma flame; feeding iron ore powder into the plasma flame area, to smelt the iron ore powder through the high-temperature plasma flame, generating reduction reaction with the hydrogen plasmas to form smelted metal iron, and then performing subsequent processing treatment. The system for making iron by hydrogen plasma smelting reduction comprises a power supply system, a gas supply system, the plasma spraying gun, a powder supply system and a smelting reduction reaction furnace. According to the method and the system, the dependency of the conventional metal iron smelting method on fossil fuel is changed, and pollution of harmful gas produced in a smelting process to the surrounding environment is avoided.

Description

Hydrogen plasma smelting reduction ironmaking method and system

technical field

The invention relates to the field of industrial metallurgy, in particular to a method and system for hydrogen plasma smelting reduction ironmaking.

Background technique

After entering the 20th century, blast furnace ironmaking developed rapidly. At present, blast furnace ironmaking technology is very mature, and it is also the main production method of ironmaking. However, with the development of blast furnaces, the problems it faces are becoming more and more severe, mainly reflected in the fact that blast furnace ironmaking requires bulk and certain-sized furnace materials, but with the rapid development of the iron and steel industry, high-quality iron ores are gradually disappearing. For lean ore, it can only be selected, and then the fine material is sintered into agglomerates, and the cost of ironmaking remains high; at the same time, the consumption of coking coal in blast furnaces is too much, and the demand for coking coal is growing rapidly, but the reserves of coking coal are limited and the supply of coking coal is insufficient. Resources are becoming increasingly scarce, and the price of coking coal is also gradually increasing, which increases the cost of ironmaking; in addition, the "three wastes" produced in the process of sintering, pelletizing, coking, and blast furnace production seriously pollute the air, land, and water. One of the factors causing severe smog in my country. These forces people to start looking for some ironmaking methods other than blast furnace ironmaking, looking for ironmaking methods that do not rely on coking coal and are more economical and environmentally friendly.

The currently developed non-blast furnace ironmaking methods mainly include direct reduction and smelting reduction. The product of the direct reduction process is solid sponge iron, and the product of the smelting reduction process is liquid pig iron. The direct reduction method is limited to using gaseous fuel, liquid fuel or non-coking coal as the energy source, and is a method for obtaining metallic iron by reduction below the softening temperature at which iron ore (or iron-containing agglomerates) is solid. Due to the low reduction temperature, the product has a porous low-density sponge-like structure, low carbon content, and the metal iron product that does not exclude gangue impurities is called direct reduced iron (DRI) or sponge iron.

Smelting reduction is another non-blast furnace ironmaking process. The proposed principle of smelting reduction is that carbon-containing molten iron reacts with iron-containing slag, that is, molten iron ore, in a high-temperature molten state. The reduction reaction speed between high temperature liquid is much faster than that between gas and solid. Later, with the progress of practical work, non-coking coal was widely used as energy source to reduce iron oxides in a high-temperature molten state. The slag and iron can be completely separated, and the process of obtaining carbon-containing molten iron similar to a blast furnace is called smelting reduction. According to the process mode, smelting reduction can be divided into three-stage, two-stage, one-stage and electrothermal methods. The three-stage smelting reduction process can be divided into two parts: reduction and smelting gas production. The reduction part is the reduction section, and the smelting gas production part includes the smelting gas production section and the gas conversion section in the same equipment. Its structural characteristics are melting A layer of carbonaceous material exists above the pool. The two-stage type is also composed of a reduction part and a smelting gas-making part, so it is collectively referred to as a two-step method with the three-stage type. The main difference between the two-stage type and the three-stage type is that there is no carbon-containing material layer above the molten pool in the smelting gas-making furnace In some two-stage processes, in order to solve the problem of reducing gas composition and temperature, a reducing gas reforming furnace is added between the smelting furnace and the reducing furnace. The one-stage process has only a smelting section and no reduction section. Both the modern one-stage process and the two-stage process use iron bath furnace smelting equipment, so the two are collectively referred to as iron bath method. The three-stage process is composed of coal-based process and coke-based process, and the two-stage and one-stage process are composed of coal-based process. The above three types are sometimes called oxygen-coal process, and the electric heating method is called electric-coal process.

In the 1980s, Sweden's SKF company transformed a direct reduction device for producing sponge iron into a Plasmared (plasma reduction) device, and the use of plasma as a heat source to produce direct reduced iron was realized industrially. In this process, the plasma generator is installed on the plasma gasifier for the coal gasification process. Coal or other fuel reacts with an oxidizing agent (such as water or oxygen) to produce direct reducing gas, which is mainly composed of H2 and CO. The high-temperature reducing gas passes through the desulfurization device, desulfurizes with dolomite, and provides it to the shaft furnace for direct reduction. Most of the heat required for coal gasification in the gasifier depends on the heat released by the carbon-oxygen combustion reaction, and a small part is supplied by the plasma generator to maintain an appropriate gasification temperature, thereby ensuring complete gasification and well controlling the quality of the reducing gas and slag temperature. The iron-containing materials used in the process are lump ore and pellets. The product is direct reduced iron with a metallization rate of 93% and a carbon content of 1.5%.

The above ironmaking processes are quite different in terms of equipment and technology, but the reliance of the technology on traditional fossil fuels has not been changed during the smelting process. Some polluting products are inevitably produced during the gasification and combustion of fossil fuels. Little improvement has been made in improving the environmental benefits of the ironmaking process.

Contents of the invention

The technical problem solved by the present invention is: to overcome the deficiencies of the prior art, to provide a hydrogen plasma smelting reduction ironmaking method and system, to change the traditional metal iron smelting method's dependence on fossil fuels, and to avoid the occurrence of The polluting gas pollutes the surrounding environment.

The technical solution of the present invention is: in order to solve the above technical problems, the smelting reduction ironmaking method of the present invention comprises the following steps,

The argon gas is fed into the plasma spray gun, and the argon gas is broken down under the action of high-frequency voltage to form an arc.

Send hydrogen and argon into the plasma spray gun at a ratio of 5:1 to 4:1. Under the action of high-frequency voltage and electric arc, hydrogen and argon are ionized into plasma, and ejected from the nozzle of the spray gun to form high-temperature plasma flame;

Send iron ore powder into the plasma flame area, so that the iron ore powder is melted by the high-temperature plasma flame, and undergoes a reduction reaction with hydrogen plasma to generate molten metallic iron;

The molten metal iron is collected for subsequent processing.

The high frequency voltage is 15000V.

In order to realize the above method, the present invention provides a hydrogen plasma smelting reduction ironmaking system, including a gas supply system, a power supply system, a plasma spray gun, a powder supply system and a smelting reduction reaction furnace; the gas supply system provides hydrogen and argon, Hydrogen and argon form a mixed gas according to the ratio of 5:1 to 4:1, which is used as the working gas of the plasma spray gun; the power supply system provides arc starting voltage and DC current for the plasma spray gun; the working gas is under the action of high-frequency voltage and arc It is ionized into high-temperature plasma, and the plasma spray gun sprays the high-temperature plasma to the smelting reduction reaction furnace to form a plasma flame; the powder supply system sends the iron ore powder to the plasma flame area of the smelting reduction reaction furnace, and the iron ore powder is heated by the high-temperature plasma The body flame melts, and undergoes a reduction reaction with hydrogen plasma to generate molten metallic iron. The smelting reduction reaction furnace is provided with a molten iron outlet and a slag outlet.

The smelting reduction reaction furnace has a water-cooled copper smelting reduction reaction furnace wall.

The powder supply system includes a powder feeder, a powder feeding pipe, a water cooling jacket for the powder feeding pipe and a turbulence chamber. The powder enters the powder bin from the feeding port, and through the drive of the main shaft, the feeding screw sends the ore powder stirred by the agitator into the turbulence chamber, where the ore powder is fully mixed with the carrier gas, and the carrier gas carries the ore powder through the powder feeding tube Entering the high-temperature plasma flame in the smelting reduction reaction furnace, the powder feeding pipe is arranged in the water cooling jacket of the powder feeding pipe.

The powder feeding pipe is a double-layer ring structure, the inner powder channel is made of wear-resistant ceramic material, and the outer layer is made of high thermal conductivity metal copper.

The advantage of the present invention compared with prior art is:

(1) The clean smelting method combining physical and chemical methods has changed the dependence on fossil fuels and improved the cleanliness of the metal iron smelting process. At the same time, the obtained products have low carbon content and oxygen content, which can be used as Target iron is used.

(2) The present invention makes full use of the characteristics of high temperature and high activity of arc plasma. The temperature of arc plasma air mass can reach more than 3000K, and the center temperature can even exceed 10000K. Melting will occur inside, and at the same time, it is highly active in a high-temperature environment, which accelerates the reduction reaction of iron oxide in the ore;

(3) The present invention fully utilizes the feature of adjustable arc plasma atmosphere, selects hydrogen as the working gas of the spray gun, and directly participates in the reduction reaction of the iron ore component iron oxide as a reducing agent at the same time.

Description of drawings

Fig. 1 is a schematic diagram of the system of the present invention;

Figure 2 is a schematic diagram of the powder feeder.

Labels in the figure: 1-plasma spray gun cathode; 2-plasma spray gun anode; 3-cathode water inlet component; 4-cathode return water component; 5-anode water inlet component; ;8-water pump; 9-heat exchanger; 10-rectifier power supply; 11-smelting reduction reactor wall; 12-insulation and sealing components; 13-powder feeder; 16-motor; 17-barometer; 18-balance gas inlet; 19-feeding port; 20-powder bin; 21-leading shaft;

detailed description

The present invention will be further described in detail below in conjunction with the accompanying drawings.

The hydrogen plasma smelting reduction ironmaking method comprises the following steps:

The argon gas is sent into the plasma spray gun, and the high-frequency voltage provided by the arc starting power supply breaks down the argon gas to generate an arc. Under the action of the arc, the hydrogen and argon are ionized into plasma, which is ejected from the nozzle of the spray gun to form a high-temperature plasma flame; the iron ore powder is sent into the plasma flame area, so that the iron ore powder is melted by the high-temperature plasma flame, The reduction reaction with hydrogen plasma produces molten metallic iron, and hydrogen is used as a reaction gas to participate in the reduction reaction of iron oxide in the ore; the molten metallic iron is collected for subsequent processing.

The high frequency arc starting voltage is 15000V.

As shown in Figure 1, the hydrogen plasma smelting reduction ironmaking system includes a gas supply system, a power supply system, a plasma spray gun, a powder supply system and a smelting reduction reaction furnace; the gas supply system provides hydrogen and argon, wherein hydrogen and argon Gas is mixed according to the ratio of 5:1 to 4:1 to form a mixed gas, which is used as the working gas of the plasma spray gun. The power supply system includes a DC rectifier power supply 10 and a high-frequency arc starting power supply. The rectifier power supply adopts the latest power electronic component IGBT (insulated gate bipolar type transistor) as the core rectification element, the main circuit adopts twelve-phase rectification, and the output DC current fluctuation rate is less than or equal to 2%; the output current of the DC rectification power supply is set to 10, and the gas supply system sends argon gas into the plasma spray gun through the intake assembly 7, The high-frequency arc-starting power supply applies high-frequency voltage between the spray gun cathode 1 and the spray gun anode 2, and the argon gas between the electrodes is instantly broken down to generate an arc, and then the DC rectifier power supply system outputs a stable DC current to maintain the arc in the plasma spray gun. Stable, the gas supply system mixes hydrogen and argon in the above ratio and continuously sends them into the plasma spray gun. Under the action of high-frequency voltage and electric arc, hydrogen and argon are ionized into high-temperature plasma, which is ejected from the nozzle of the spray gun to the melting reduction reaction Furnace, forming a high-temperature plasma flame. Therefore, the plasma flame is actually a high-temperature rotating hydrogen and argon plasma flow at high speed. On the one hand, the high-temperature rotating flow at the outlet of the spray gun realizes the cyclone stable arc, and on the other hand, it can increase the mixing reaction time of the high-temperature plasma and ore powder.

The powder supply system sends iron ore powder to the plasma flame area of the smelting reduction reaction furnace. The iron ore powder is melted by the high-temperature plasma flame, and the ionized hydrogen becomes hydrogen plasma as a reducing agent, which undergoes a reduction reaction with iron oxide in the ore to form Metallic iron in molten state. The molten iron contained in the ore and obtained by iron oxide reduction flows out from the molten iron outlet at the bottom of the smelting reduction reaction furnace and enters subsequent equipment for processing. The impurity components and oxides in the ore float on the surface of the molten iron in a molten state. The slag flows out from the outlet and enters the subsequent equipment for processing. The smelting reduction reaction container furnace has a water-cooled copper smelting reduction reaction furnace wall 11, a molten iron outlet, a molten slag outlet and a high temperature resistant insulating sealing assembly matched with the plasma spray gun.

The powder supply system includes a powder feeder 13 , a powder feed pipe 15 , a water cooling jacket 14 for the powder feed pipe and a turbulence chamber 24 . As shown in Figure 2, the powder feeder 13 includes a feeding port 19, a powder bin 20, a main shaft 21 arranged in the powder bin 20, an agitator 22 and a feeding screw 23, and the iron ore is crushed by a crusher, pulverizer The ore powder dried by the grinding and drying machine enters the powder bin 20 through the feeding port 19, and through the transmission of the main shaft 21, the feeding screw 23 sends the ore powder stirred by the agitator 22 into the turbulence chamber 24, and the ore powder and the The carrier gas is fully mixed. The carrier gas can be argon or other inert gas. The carrier gas carries the ore powder through the powder feeding pipe 15 into the root of the high-temperature plasma flame in the smelting reduction reaction furnace, and mixes and exchanges heat with the high-temperature plasma. Under the action of the plasma flame, the ore powder is melted in a short time, and the iron oxide component in the ore produces a chemical reduction reaction with the highly active hydrogen plasma. During operation, calculate the powder feeding speed of the powder feeder by measuring the front and rear weights of the powder bin (the change in the weight of the powder bin per unit time is the powder feeding speed), and control the powder feeding amount by adjusting the motor 16 speeds. At the same time, in order to ensure smooth and even powder falling , A stream of gas is drawn from the carrier gas outside the bin as a balance gas and enters the powder bin through the balance gas inlet 18, and the barometer 17 is used to monitor the air pressure in the powder bin. The powder feeding pipe 15 is arranged in the powder feeding pipe water cooling jacket 14 on the periphery of the spray gun to protect the powder feeding pipe from being burned by the high temperature in the reaction furnace. The powder feeding pipe 15 is a double-layer ring structure, the inner powder channel is made of wear-resistant ceramic material, and the outer layer is made of high thermal conductivity metal copper.

The plasma spray gun includes a spray gun cathode 1, an anode 2, a cathode water inlet assembly 3, a cathode return water assembly 4, an anode water inlet assembly 5, an anode return water assembly 6 and an air intake assembly 7, and the cooling water passes through the cathode water inlet assembly 3 respectively And the anode water inlet assembly 5 enters to cool the anode and the cathode, preventing the electrodes from being ablated by the high temperature arc. Both the cathode and the anode of the plasma torch are designed as a tubular structure. In the application, different product production scales can be realized by adjusting the power of the plasma torch, the number of spray guns, the amount of powder supplied and the volume of the reaction furnace.

The cooling water system consists of a deionized water tank, a water pump and a heat exchanger to provide cooling water for the above-mentioned systems.

The content that is not described in detail in the description of the present invention belongs to the well-known technology of those skilled in the art.

Claims (6)

1. A hydrogen plasma smelting reduction ironmaking method is characterized in that comprising the steps: Send argon gas into the plasma spray gun, and the argon gas is broken down under the action of high-frequency voltage to form an arc; Send hydrogen and argon into the plasma torch at a ratio of 5:1 to 4:1. Under the action of high-frequency voltage and electric arc, hydrogen and argon are ionized into plasma, which is ejected from the nozzle of the plasma torch to form a high temperature plasma flame; Send iron ore powder into the high-temperature plasma flame area, so that the iron ore powder is melted by the high-temperature plasma flame, and undergoes a reduction reaction with hydrogen plasma to generate molten metallic iron; The molten metal iron is collected for subsequent processing. 2. The hydrogen plasma smelting reduction ironmaking method according to claim 1, characterized in that the high frequency voltage is 15000V. 3. A system for realizing the hydrogen plasma smelting reduction ironmaking method described in claim 1 or 2, characterized in that it comprises a gas supply system, a power supply system, a plasma spray gun, a powder supply system and a smelting reduction reaction furnace; The gas system provides hydrogen and argon to the plasma spray gun, and the hydrogen and argon form a mixed gas according to the ratio of 5:1 to 4:1, which is used as the working gas of the plasma spray gun; the power supply system provides the arc starting voltage and DC current for the plasma spray gun The working gas is ionized into high-temperature plasma under the action of high-frequency voltage and electric arc, and the plasma spray gun sprays the high-temperature plasma to the smelting reduction reaction furnace to form a high-temperature plasma flame; the powder supply system sends the iron ore powder to the smelting reduction reaction In the high-temperature plasma flame area of the furnace, the smelting reduction reaction furnace is provided with a molten iron outlet and a molten slag outlet. 4. The hydrogen plasma smelting reduction ironmaking system according to claim 3, characterized in that, the smelting reduction reaction furnace has a water-cooled copper smelting reduction reaction furnace wall (11). 5. The hydrogen plasma smelting reduction ironmaking system according to claim 3, characterized in that, the powder supply system comprises a powder feeder (13), a powder feed pipe (15), a powder feed pipe water cooling jacket (14) And the turbulence chamber (24), the powder feeder (13) includes a feeding port (19), a powder bin (20) and a capstan (21), an agitator (22) and a feeding screw arranged in the powder bin (20) (23), the ore powder enters the powder bin (20) from the feeding port (19), and through the transmission of the capstan (21), the feeding screw (23) sends the ore powder stirred by the agitator (22) into the turbulence chamber ( 24), the ore powder is fully mixed with the carrier gas in the turbulence chamber (24), and the carrier gas carries the ore powder through the powder feeding pipe (15) into the high-temperature plasma flame in the smelting reduction reaction furnace, and the powder feeding pipe (15) is arranged at Inside the water cooling jacket (14) of the powder feeding pipe. 6. The hydrogen plasma smelting reduction ironmaking system according to claim 5, characterized in that, the powder feeding pipe (15) is a double-layer ring structure, the inner layer powder channel is made of wear-resistant ceramic material, and the outer layer Copper is a metal with high thermal conductivity.