CN110195139B - Iron ore low-temperature reduction-normal-temperature slag-iron separation-electric furnace steel making process - Google Patents
Iron ore low-temperature reduction-normal-temperature slag-iron separation-electric furnace steel making process Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/004—Making spongy iron or liquid steel, by direct processes in a continuous way by reduction from ores
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/0066—Preliminary conditioning of the solid carbonaceous reductant
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/0073—Selection or treatment of the reducing gases
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/08—Making spongy iron or liquid steel, by direct processes in rotary furnaces
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/52—Manufacture of steel in electric furnaces
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Abstract
The invention relates to a process for preparing steel from an iron ore by low-temperature reduction, normal-temperature slag iron separation and an electric furnace, wherein in the reduction process of a rotary kiln for pellet ore or block iron ore, low-rank coal is sprayed into the middle and rear sections of the rotary kiln through compressed air, the coal is pyrolyzed into tar, pyrolysis coal gas and carbon residue in the rapid heating process of the high-temperature section, the pyrolysis coal gas is used as a reducing agent of a material to be reduced, the tar is used as a fuel of the rotary kiln, the pellet ore or block iron ore selectively reduces the iron in the iron ore, the reduced material and the carbon residue mixture are subjected to dry magnetic separation, the obtained carbon residue is returned and mixed into the material to be fed into the kiln for recycling, and the obtained metal material is subjected to dry grinding, dry magnetic separation, iron powder briquetting and electric furnace smelting to obtain pure steel. The invention greatly utilizes tar, pyrolysis gas and carbon residue in the low-rank coal, only reduces iron but not other elements in the selective reduction process, and lays a foundation for preparing pure steel.
Description
Technical Field
The invention belongs to the technical field of metallurgy and mineral engineering, and relates to a process for manufacturing steel by using an electric furnace, which comprises the steps of low-temperature reduction of iron ore, normal-temperature slag-iron separation and electric furnace.
Background
Blast furnace iron making has been developed for hundreds of years, and the process has reached a fairly perfect stage. Blast furnace iron making mainly comprises the working procedures of coking, sintering, pelletizing, blast furnace and the like, is the leading flow of modern steel smelting, and has the characteristics of high yield and high product quality. But the problems of long flow, large investment, environmental pollution and the like are brought while the iron burning production process is increasingly perfect and large-scale. Blast furnace iron making requires high-grade lump or certain size burden, but with the rapid development of the steel industry scale, high-grade iron ore resources are gradually reduced. When lean ore is used as an iron-making raw material, the lean ore needs to be ground and magnetically separated, then iron concentrate needs to be sintered and agglomerated, and meanwhile, blast furnace iron making needs to consume a large amount of coking coal, so that the demand of the coking coal is rapidly increased, but because the coking coal is limited in reserve, insufficient in supply and poor in resources, the price of the coking coal is gradually increased, and the iron-making cost of the blast furnace is increased. In addition, the three wastes generated in the processes of agglomerate agglomeration, pellet production, coking coal coking and blast furnace iron making seriously pollute the atmosphere, land and water resources, and people are forced to find some economic and environment-friendly non-blast furnace iron making methods which do not depend on coking coal.
The non-blast furnace ironmaking uses non-coking coal as energy, saves the procedures of sintering, pelletizing and the like in the traditional process, shortens the production flow, has strong adaptability to raw materials and fuels, good controllability of the process, low energy consumption and little pollution, and is considered as an ironmaking process with energy conservation, environmental protection, small investment and low production cost. In non-blast furnace iron making, main equipment for coal-based direct reduction comprises a rotary kiln, a shaft furnace, a tunnel kiln and the like. The tunnel kiln method for producing the direct reduced iron is suitable for small-scale production and has small investment. At present, the main reasons for non-blast furnace ironmaking development are as follows: (1) the reduction of the coal reserves for coking and the quality reduction, and an iron-making method without coke is required to be searched; (2) the non-blast furnace ironmaking uses no or less coke, can use coal, oil, coal gas and the like as energy sources, can save the coking process of the conventional process, does not use gas making, simplifies the steel production flow, and has the characteristics of less investment, quick effect taking and suitability for the development of medium and small steel enterprises. (3) The non-blast furnace iron making has strong adaptability to raw materials, the common iron ore can be utilized without treatment, and the composite iron ore with symbiotic metal can be utilized, so that not only can the materials such as lump ore, pellet ore, concentrate powder, powder ore and the like be used, but also iron-containing dust and industrial waste materials such as blast furnace dust, converter furnace dust, gas ash, sintering process ash and the like can be widely treated, and the method is also an important method for developing comprehensive utilization of resources.
In the prior non-blast furnace iron making production in China, although the problem of coke is solved by the direct reduction process of the iron ore, the requirement of the concentrate is higher than that of a high furnace, and the solid sponge iron product is mainly supplied to an electric furnace for steel making and cannot meet the requirement of large-scale production of a converter or a blast furnace. In order to solve the problem, a new process for directly carrying out melting reduction on high-grade concentrate powder is provided, and the basic idea is to divide the blast furnace action into two steps to complete the process: the first step is pre-reduction, and the main task is to extract oxygen from iron ore concentrate and provide a pre-reduction raw material; the second step is deep reduction, and the main tasks are melting, refining and slag iron separation, and high-temperature reducing coal gas is provided for the pre-reduction furnace. This is in fact equivalent to dividing the blast furnace operation into two parts independent and closely linked to each other, with their respective efforts reaching the highest targets. None of the above inventions simultaneously solves the following four problems: (1) the reducing gas is produced on the basis of comprehensive utilization of low-rank coal; (2) the iron pellets or the lump ore are selectively reduced by using reducing gas instead of being excessively reduced; (3) cleaning and smelting the reduction product to obtain pure steel; (4) energy saving, environmental protection and low cost. Therefore, none of them can be compared in an integrated way with the currently commonly used "blast furnace-converter" flow.
According to the characteristics of low investment, quick response and high ore reduction quality of rotary kiln equipment, the invention provides a low-temperature reduction-normal-temperature slag-iron separation-electric furnace steel making process of rotary kiln iron ore for improving the traditional iron burning production process, shortening the production flow, reducing coke consumption and reasonably utilizing system energy on the basis of the traditional direct reduction production process of rotary kiln iron ore.
Disclosure of Invention
The invention provides a low-temperature reduction-normal-temperature slag-iron separation-electric furnace steel making process of iron ore, which adopts low-rank coal which cannot be coked as an energy source and a reducing agent, adopts a metalized material produced by a rotary kiln, and adopts an air-magnetic synchronous combined selection technology to prepare high-purity iron powder for the metalized material, so that a new steel smelting process which is simple in process, energy-saving and environment-friendly and can obtain pure iron powder by one-step is formed, and a material basis is laid for the research and development of a process technology of 'metallurgical coal-based reduction (low-temperature iron making)' -dry grinding and dry separation (normal-temperature slag-iron separation) '-electric furnace (steel making)'.
The process of iron ore low-temperature reduction, normal-temperature slag iron separation and electric furnace steel making is divided into four parts: firstly, pyrolyzing low-rank coal into 3 products of tar, pyrolysis gas and carbon residue; secondly, the carbon residue after pyrolysis is used as a raw material and is reduced with water vapor or CO generated in the process of reducing the iron ore2Reacting to prepare reducing gas; thirdly, carrying out selective gas-based direct reduction reaction on the pyrolysis coal gas and the reducing gas when the pyrolysis coal gas and the reducing gas pass through the material layer of the pellet ore or the lump ore, and only reducing iron in the pyrolysis coal gas to obtain a metalized material; and fourthly, performing air magnetic synchronous combined selection on the metalized material after dry grinding to prepare the ultrapure metalized iron powder.
Specifically, the process for producing steel by using iron ore through low-temperature reduction, normal-temperature slag iron separation and electric furnace uses low-rank coal as an energy source and a reducing agent for reducing pellets or lump ores. Pure iron powder is prepared according to the following method:
A) mixing pellets with the particle size of 8-16mm or massive iron ore with the particle size of 10-30mm with 5-10mm carbon residue according to the proportion of 100:12-15, and adding the mixture from the kiln inlet end of the rotary kiln. The temperature of the materials is gradually increased under the action of high temperature in the rotary kiln, when the temperature reaches 400-450 ℃, the iron ore starts to perform reduction reaction with carbon, and when the temperature reaches 1000-1100 ℃, the reduction reaction is vigorously performed.
B) When the reduction reaction of the iron ore in the high-temperature section of the rotary kiln is carried out to the middle and later stages, the reduction reaction speed is reduced, at the moment, the low-rank coal is sprayed into the middle and later stages of the rotary kiln by using compressed air through a spray gun, and after the coal is contacted with the high-temperature material in the rotary kiln, the coal can be pyrolyzed when the temperature reaches 500-900 ℃ in the temperature rise process at the temperature of 800 ℃/min for adding heat to obtain spongy carbon residue and byproduct pyrolysis coal gas and tar, and the tar can be used as the fuel of the rotary kiln.
C) The pyrolysis gas in the rotary kiln is contacted with the iron ore in the process of flowing in the material layer and escaping from the material layer, so that the iron ore can be further reduced, and CO generated by the reduction of the iron ore2And water vapor and carbon residue are subjected to carbon gasification reaction at 800-1100 ℃, CO and H with higher reducibility can be obtained2(ii) a Due to H2The molecular radius of the catalyst is smaller, and the catalyst has higher reducibility when contacting with the iron ore, so that the low-temperature hydrogen reduction of the iron ore can be realized.
D) The temperature of the reduction section of the rotary kiln is controlled to be 1050 ℃ and 1050 ℃, the high-temperature reduction time is 60-90min, so that the pellet ore or the massive iron ore and the reduction gas in the kiln can be subjected to selective gas-based direct reduction to obtain a reduction product of the reduced iron mixed with other unreduced oxides;
E) in the reduction process of the iron ore, gas escaping from the interior of the material contains certain combustible components, combustion air is blown into the middle-rear section of the rotary kiln to combust the combustible components, and heat generated by combustion is supplied to the rotary kiln for self utilization.
F) After the 900-plus 950-DEG C high-temperature reducing material from the rotary kiln is subjected to indirect anaerobic cooling, the normal-temperature reducing material is subjected to dry magnetic separation by using a drum-type dry separator to obtain a metalized material and carbon residue, and the carbon residue is returned to a batching system to be used as a batching for pellet ore or blocky iron ore for recycling.
G) The metal material is ground to minus 200 meshes by a dry grinding mill and accounts for more than 90 percent, and then dry magnetic separation is carried out by an air-magnetic synchronous combined separation device, so that high-purity iron powder with the iron grade of more than 90 percent, the metallization rate of more than 95 percent and the metal recovery rate of more than 90 percent can be obtained after normal-temperature slag-iron separation is realized.
H) The high-purity iron powder is cold-pressed into a cold-pressed block of 5-40mm by a briquetting machine, and then the cold-pressed block is added into an electric furnace for smelting, so that the pure steel can be obtained by a one-step method.
Further, the metal cold-pressed block is added into an electric furnace with an alkaline furnace lining, and the auxiliary material lime is added for smelting for 1-2 hours at the smelting temperature of 1600-1680 ℃, so that the pure steel can be obtained. Wherein the addition amount of lime is (SiO) in the reduction product2+P2O5+A1203) 2-4 times of the total mass.
The invention controls the low-rank coal to be heated to 500-900 ℃ at the heating rate of 600-800 ℃/min for pyrolysis, so that the ratio of tar to pyrolysis gas obtained in the pyrolysis process is 1: 2-6, namely, each ton of low-rank coal can be pyrolyzed to obtain 80-150Kg of tar and 200 Nm of pyrolysis gas3And 400-700Kg of carbon residue. Wherein about 50-l00Kg ash is mixed in the carbon residue.
The invention mixes the carbon residue obtained by pyrolysis into pellet ore or massive iron ore, when the temperature of the ore-coal mixture rises to 800-2The generated carbon gasification reaction is used for preparing reducing gas, and the obtained reducing gas contains (CO + H)2) The volume ratio reaches more than 80 percent, and the reducing gas and the pellet ore or the blocky iron ore are subjected to selective gas-based direct reduction reaction in the material layer, so that the iron ore can be rapidly reduced at high temperature.
The selective gas-based direct reduction reaction of the invention means that the reducing gas only reduces the iron oxide in the pellet ore or the lump iron ore and does not reduce other oxides in the pellet ore or the lump iron ore in the reduction process, and the effect is realized by controlling the retention time of the pellet ore or the lump iron ore in the reduction section of the rotary kiln under the reduction reaction condition.
The retention time of the pellet ore or the lump iron ore at the temperature in the reduction section of the reduction kiln is controlled, so that the SiO in the pellet ore or the lump iron ore can be ensured2、P2O5Oxides such as MnO and the like are not reduced, but only oxides of iron therein are reduced.
The heat generated by mixing and burning the tar generated after the pyrolysis of the low-rank coal in the rotary kiln and the gas products escaping from the interior of the materials after the reduction reaction of the iron ore and the combustion air can meet the heat requirement in the direct reduction of the iron ore in the whole rotary kiln.
Furthermore, the direct reduction material adopts dry grinding for monomer dissociation of metal iron and slag, and the ground material adopts an air-magnetic synchronous combined selection device for normal-temperature slag iron separation, so that high-purity iron powder can be obtained under the condition that the metallized iron powder is not oxidized.
The invention has the beneficial effects that:
(1) the reducing gas prepared from the low-rank coal is pyrolyzed at a medium heating rate, and tar and all pyrolysis gas accounting for 8-15% of the total mass of the low-rank coal are extracted to the utmost extent. The low-rank coal which is low in price and cannot be coked is pyrolyzed under the heating condition in the rotary kiln, so that tar, pyrolysis coal gas and residual carbon in the low-rank coal are obtained to the maximum extent, the pyrolysis coal gas is used as reducing gas, the residual carbon is returned to ingredients by adopting a carbon circulation technology for utilization, and the tar is used as fuel of the rotary kiln for utilization.
(2) In the coal-based direct reduction process, the selective reduction is realized by controlling the process parameters, only iron is reduced, and other elements are not reduced, so that the foundation is laid for preparing the super-pure steel.
(3) The invention can make the oxidation period and the reduction period disappear at the same time in the traditional electric furnace smelting process, namely the complex process of oxygen blowing, deoxidation, refining and impurity removal in the steelmaking process does not exist, and the high-purity iron powder is obtained by using a simpler process.
(4) Compared with the traditional blast furnace-converter flow, the realization of the process flow of the invention not only enables the iron and steel smelting to completely get rid of the history of iron making depending on coke, but also enables the flow of obtaining pure steel to be greatly simple. The invention has less emissions, is more concise, energy-saving and environment-friendly, reduces the environmental emission pressure of the ferrous metallurgy process of a blast furnace-converter and has obvious cost advantage.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Detailed Description
The invention relates to raw materials and equipment, which comprises the following components: pellet ore or lump iron ore, a mixer, a rotary kiln, an anaerobic cooler, a dry magnetic separator, a dry powder mill, a wind-magnetic synchronous combined separator set, an iron powder briquetting machine, an electric furnace and the like.
Example 1
(1) After pellets with the particle size of 8-16mm or massive iron ore with the particle size of 10-30mm and residual carbon with the particle size of 5-10mm are mixed according to the proportion of 100:15, the mixture is added from the kiln inlet end of the rotary kiln. The temperature of the materials is gradually increased under the action of high temperature in the rotary kiln, when the temperature reaches 400-450 ℃, the iron ore starts to perform reduction reaction with carbon, and when the temperature reaches 1000-1100 ℃, the reduction reaction is vigorously performed.
(2) When the reduction reaction of the iron ore in the high-temperature section of the rotary kiln is carried out to the middle and later stages, the reduction reaction speed is reduced, at the moment, the low-rank coal is sprayed into the middle and later stages of the rotary kiln by using compressed air through a spray gun, and after the coal is contacted with the high-temperature material in the rotary kiln, the coal can be pyrolyzed when the temperature reaches 500-900 ℃ in the temperature rise process at the temperature of 800 ℃/min for adding heat to obtain spongy carbon residue and byproduct pyrolysis coal gas and tar, and the tar can be used as the fuel of the rotary kiln.
(3) The pyrolysis gas in the rotary kiln is contacted with the iron ore in the process of flowing in the material layer and escaping from the material layer, so that the iron ore can be further reduced, and CO generated by the reduction of the iron ore2And water vapor and carbon residue are subjected to carbon gasification reaction at 800-1100 ℃, CO and H with higher reducibility can be obtained2(ii) a Due to H2The molecular radius of the catalyst is smaller, and the catalyst has higher reducibility when contacting with the iron ore, so that the low-temperature hydrogen reduction of the iron ore can be realized.
(4) The temperature of the reduction section of the rotary kiln is controlled to be 1050 ℃ and the high-temperature reduction time is controlled to be 60min, so that the pellet ore or the massive iron ore and the reduction gas in the kiln can be subjected to selective gas-based direct reduction to obtain a reduction product of the reduced iron mixed with other unreduced oxides;
(5) in the reduction process of the iron ore, gas escaping from the interior of the material contains certain combustible components, combustion air is blown into the middle-rear section of the rotary kiln to combust the combustible components, and heat generated by combustion is supplied to the rotary kiln for self utilization.
(6) After the 900-plus 950-DEG C high-temperature reducing material from the rotary kiln is subjected to indirect anaerobic cooling, the normal-temperature reducing material is subjected to dry magnetic separation by using a drum-type dry separator to obtain a metalized material and carbon residue, and the carbon residue is returned to a batching system to be used as a batching for pellet ore or blocky iron ore for recycling.
(7) The metallic material is ground to-200 meshes by a dry grinding mill and accounts for more than 90%, and then dry magnetic separation is carried out by an air-magnetic synchronous combined separation device, so that high-purity iron powder with the iron grade of 94%, the metallization rate of 95% and the metal recovery rate of 93% is obtained after normal-temperature slag-iron separation is realized.
(8) The high-purity iron powder is cold-pressed into a cold-pressed block of 5-40mm by a briquetting machine, and then the cold-pressed block is added into an electric furnace for smelting, so that the pure steel can be obtained by a one-step method.
Example 2
(1) After pellets with the particle size of 8-16mm or massive iron ore with the particle size of 10-30mm and residual carbon with the particle size of 5-10mm are mixed according to the proportion of 100:12, the mixture is added from the kiln inlet end of the rotary kiln. The temperature of the materials is gradually increased under the action of high temperature in the rotary kiln, when the temperature reaches 400-450 ℃, the iron ore starts to perform reduction reaction with carbon, and when the temperature reaches 1000-1100 ℃, the reduction reaction is vigorously performed.
(2) When the reduction reaction of the iron ore in the high-temperature section of the rotary kiln is carried out to the middle and later stages, the reduction reaction speed is reduced, at the moment, the low-rank coal is sprayed into the middle and later stages of the rotary kiln by using compressed air through a spray gun, and after the coal is contacted with the high-temperature material in the rotary kiln, the coal can be pyrolyzed when the temperature reaches 500-900 ℃ in the temperature rise process at the temperature of 800 ℃/min for adding heat to obtain spongy carbon residue and byproduct pyrolysis coal gas and tar, and the tar can be used as the fuel of the rotary kiln.
(3) The pyrolysis gas in the rotary kiln is contacted with the iron ore in the process of flowing in the material layer and escaping from the material layer, so that the iron ore can be further processedReduction of iron ore to CO2And water vapor and carbon residue are subjected to carbon gasification reaction at 800-1100 ℃, CO and H with higher reducibility can be obtained2(ii) a Due to H2The molecular radius of the catalyst is smaller, and the catalyst has higher reducibility when contacting with the iron ore, so that the low-temperature hydrogen reduction of the iron ore can be realized.
(4) The temperature of the reduction section of the rotary kiln is controlled to be 1050 ℃ and the high-temperature reduction time is controlled to be 90min, so that the pellet ore or the massive iron ore and the reduction gas in the kiln can be subjected to selective gas-based direct reduction to obtain a reduction product of the reduced iron mixed with other unreduced oxides;
(5) in the reduction process of the iron ore, gas escaping from the interior of the material contains certain combustible components, combustion air is blown into the middle-rear section of the rotary kiln to combust the combustible components, and heat generated by combustion is supplied to the rotary kiln for self utilization.
(6) After the 900-plus 950-DEG C high-temperature reducing material from the rotary kiln is subjected to indirect anaerobic cooling, the normal-temperature reducing material is subjected to dry magnetic separation by using a drum-type dry separator to obtain a metalized material and carbon residue, and the carbon residue is returned to a batching system to be used as a batching for pellet ore or blocky iron ore for recycling.
(7) The metal material is ground to-200 meshes by a dry grinding mill and accounts for more than 90%, and then dry magnetic separation is carried out by an air-magnetic synchronous combined separation device, so that high-purity iron powder with the iron grade of 95%, the metallization rate of 96% and the metal recovery rate of 92% is obtained after normal-temperature slag-iron separation is realized.
(8) The high-purity iron powder is cold-pressed into a cold-pressed block of 5-40mm by a briquetting machine, and then the cold-pressed block is added into an electric furnace for smelting, so that the pure steel can be obtained by a one-step method.
Claims (2)
1. A process for producing steel from iron ore by low-temperature reduction, normal-temperature slag iron separation and electric furnace is characterized by comprising the following steps: A) after mixing pellets with the particle size of 8-16mm or massive iron ore with the particle size of 10-30mm and carbon residue with the particle size of 5-10mm according to the proportion of 100:12-15, adding the mixture from the kiln inlet end of the rotary kiln, gradually raising the temperature of the material under the action of high temperature in the rotary kiln, starting reduction reaction between the iron ore and carbon when the temperature reaches 400-450 ℃, and violently performing the reduction reaction when the temperature reaches 1000-1100 ℃;
B) when the reduction reaction of the iron ore in the high-temperature section of the rotary kiln is carried out to the middle and later stages, the reduction reaction speed is reduced, at the moment, the low-rank coal is sprayed into the middle and later sections of the rotary kiln by using compressed air through a spray gun, and after the coal is contacted with high-temperature materials in the rotary kiln, the coal is pyrolyzed when the temperature reaches 500-900 ℃ in the temperature rise process at 800 ℃/min through 600-plus materials to obtain spongy carbon residue and byproduct pyrolysis gas and tar, and the tar is used as the fuel of the rotary kiln;
C) the pyrolysis gas in the rotary kiln contacts with the iron ore in the process of flowing upwards in the material layer and escaping from the material layer, so that the iron ore can be further reduced, and CO generated by the reduction of the iron ore2And water vapor and carbon residue are subjected to carbon gasification reaction at 800-1100 ℃ to obtain CO and H with higher reducibility2(ii) a Due to H2The molecular radius of the iron ore is smaller, and the iron ore has higher reducibility when being contacted with the iron ore, so that the low-temperature hydrogen reduction of the iron ore can be realized;
D) carrying out selective gas-based direct reduction on pellet ore or blocky iron ore and reducing gas in the kiln by controlling the temperature of a reduction section of the rotary kiln to be 1000-1050 ℃ and the high-temperature reduction time to be 60-90min to obtain a reduction product of the reduced iron mixed with other unreduced oxides;
E) in the reduction process of the iron ore, gas escaping from the interior of the material contains certain combustible components, combustion air is blown into the middle-rear section of the rotary kiln to combust the combustible components, and heat generated by combustion is supplied to the rotary kiln for self utilization;
F) after the 900-plus 950 ℃ high-temperature reducing material from the rotary kiln is subjected to indirect anaerobic cooling, the normal-temperature reducing material is subjected to dry magnetic separation by using a drum-type dry separator to obtain a metalized material and carbon residue, and the carbon residue is returned to a batching system to be used as a batching for pellet ore or blocky iron ore for recycling;
G) the metal material is ground to minus 200 meshes by a dry grinding mill and accounts for more than 90 percent, and dry magnetic separation is carried out by an air-magnetic synchronous combined separation device, so that high-purity iron powder with the iron grade of more than 90 percent, the metallization rate of more than 95 percent and the metal recovery rate of more than 90 percent is obtained after normal-temperature slag-iron separation is realized;
H) and (3) cold-pressing the high-purity iron powder into a cold-pressed block of 5-40mm by using a briquetting machine, adding the cold-pressed block into an electric furnace for smelting, and obtaining high-quality pure steel by a one-step method.
2. The process of claim 1, wherein the cold-pressed metal block is added to an electric furnace with a basic lining, and lime is added as an auxiliary material at the smelting temperature of 1600-1680 ℃ for smelting for 1-2 hours to obtain pure steel; wherein the addition amount of lime is SiO in the reduction product2+P2O5+A12032-4 times of the total mass.
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| CN113684336A (en) * | 2021-07-21 | 2021-11-23 | 酒泉钢铁(集团)有限责任公司 | Direct reduction process of iron ore coal-based step-by-step oxygenation-segmented hydrogen increasing rotary kiln |
| CN113774179A (en) * | 2021-09-24 | 2021-12-10 | 四川阳华环保科技有限公司 | Method for producing pure iron and iron-carbon alloy by adopting rotary kiln |
| CN113981164A (en) * | 2021-10-25 | 2022-01-28 | 山东大学 | Process and system for co-mechanical activation of iron ore-carbon material in reducing atmosphere |
| CN115216572B (en) * | 2022-01-06 | 2023-10-27 | 中冶长天国际工程有限责任公司 | Method and system for directly reducing iron oxide and application thereof |
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