CN105755195A - Method for directly preparing molten steel from high-silicon iron ores - Google Patents

Method for directly preparing molten steel from high-silicon iron ores Download PDF

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CN105755195A
CN105755195A CN201610225839.4A CN201610225839A CN105755195A CN 105755195 A CN105755195 A CN 105755195A CN 201610225839 A CN201610225839 A CN 201610225839A CN 105755195 A CN105755195 A CN 105755195A
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carbon
molten steel
pelletizing
silicon iron
iron ore
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CN105755195B (en
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唐惠庆
秦艳齐
付秀峰
董志磊
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Beijing University of Technology
University of Science and Technology Beijing USTB
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University of Science and Technology Beijing USTB
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    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21BMANUFACTURE OF IRON OR STEEL
    • C21B13/00Making spongy iron or liquid steel, by direct processes
    • C21B13/10Making spongy iron or liquid steel, by direct processes in hearth-type furnaces
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21BMANUFACTURE OF IRON OR STEEL
    • C21B13/00Making spongy iron or liquid steel, by direct processes
    • C21B13/0006Making spongy iron or liquid steel, by direct processes obtaining iron or steel in a molten state
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21BMANUFACTURE OF IRON OR STEEL
    • C21B13/00Making spongy iron or liquid steel, by direct processes
    • C21B13/12Making spongy iron or liquid steel, by direct processes in electric furnaces
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21BMANUFACTURE OF IRON OR STEEL
    • C21B13/00Making spongy iron or liquid steel, by direct processes
    • C21B13/14Multi-stage processes processes carried out in different vessels or furnaces
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00Preliminary treatment of ores or scrap
    • C22B1/14Agglomerating; Briquetting; Binding; Granulating
    • C22B1/24Binding; Briquetting ; Granulating
    • C22B1/242Binding; Briquetting ; Granulating with binders
    • C22B1/244Binding; Briquetting ; Granulating with binders organic

Abstract

The invention discloses a method for directly preparing molten steel from high-silicon iron ores. The method comprises the following steps of: preparation and grinding of biomass charcoal, grinding and ball milling of the high-silicon iron ores, preparation of carbon-containing pellets, direct reduction, and separation of high-temperature iron slag. Compared with existing methods for processing the high-silicon iron ores, the method has the advantages that biomass charcoal is prepared from wide-source agricultural biomass waste and is utilized as a reducer for preparing the carbon-containing pellets, and the carbon-containing pellets are subjected to direct reduction and electric furnace high-temperature melting by virtue of a commercial FASTMELT process; by controlling reduction conditions, high metallized pellets with extremely carbon residue are obtained in a direct reduction stage; and the molten steel with the quality directly reaching or exceeding converter tapping standards is directly obtained in a high-temperature melting stage. The method has the advantages that the recovery rate of iron is high, the quality of the obtained liquid-state low-carbon and low-silicon molten steel is good, and the like. According to the method, the conventional sintering-blast furnace-converter flow for iron-making and steel-making is avoided, so that the flow of processing the high-silicon iron ores is greatly simplified.

Description

A kind of method directly preparing molten steel from high-silicon iron ore
Technical field
The invention belongs to belong to Ferrous Metallurgy-non-blast furnace ironmaking field, relate to difficulty and select high-silicon iron ore (high siliceous hematite) Utilize technique, a kind of method directly preparing molten steel from high-silicon iron ore.
Background technology
Along with abundant ore source the poorest in worldwide, some unvalued iron ore deposits started to be opened in the past Adopt and utilize.Owing to the gangue content of these iron mines is high, and it is difficult to improve Iron grade or reduction by conventional technique of preparing Gangue content, therefore, the utilization of these Complex Iron Ores is just very restricted.Wherein high-silicon iron ore (the highest siliceous red ferrum Ore deposit) it is a kind of common iron mine difficult inferior, at the more southern provinces (such as Hainan Province) of China, such high-silicon iron ore ratio Relatively universal (Hainan mining and metallurgy, 1 (1997): 1-3).Simultaneously as import price is extremely low, China also from overseas (such as African country's hair Li Taniya) some such high-silicon iron ores of import.The mineral phase structure of these mineral is mainly bloodstone, quartz and pole A small amount of calcium oxide, magnesium oxide and alumina impurities, quartz with small particulate form be embedded in bloodstone mutually in;Remaining is harmful to Element such as sulfur, the extremely low even trace of phosphorus content.After conventional ore dressing, the Iron grade in this ore deposit has a more substantial increase, Ke Yida To more than 55wt%, but the content of silicon dioxide is between 9-14wt%.
The system of low silicon smelting generally carried out by current blast furnace.First the low silicon smelting of blast furnace is that blast furnace self ironmaking is energy-conservation Requirement.If SiO in blast furnace burden2Content high, blast furnace ironmaking cost can be caused to be substantially increased.Mainly show themselves in that blast furnace refines The iron coke per ton ratio of ferrum rises;Sintering feed alkalescence CaO flux addition to increase;The ton scum amount of blast furnace ironmaking rises;In molten iron Silicone content rises.Next to that the requirement that follow-up pneumatic steelmaking is to molten iron silicon content.Converter current steel-making does not typically allow into stove ferrum Water silicone content is more than 0.3wt%.And less-slag operation and the silicone content of molten iron being had higher requirement without slag steel-making.With this The Steel Production Flow Chart of blast furnace-converter requires that in sintering deposit, dioxide-containing silica not can exceed that 5wt%.Therefore, for SiO2Contain The amount high-silicon iron ore more than 10wt%, the viewpoint of most domestic iron and steel enterprise is " the type high-silicon iron ore is given for free and all do not wanted ". Based on above reason, in some iron and steel enterprise, such high-silicon iron ore only by with other fine iron breeze rational ore matchings after Can obtain a small amount of application on sintering, the addition of this type of high-silicon iron ore is about 10% left side of sintering breeze total amount at present Right.Larger-scale for sintering-flow process of blast furnace ironmaking is difficult to realize.As wanted to remove titanium dioxide in this high-silicon iron ore further Silicone content is to meet the requirement of blast furnace ironmaking, and common beneficiation method cannot realize, and needs to use complicated technique of preparing.At present Such iron mine is carried ferrum and includes except the method for silicon: sodium roasting associating magnetic separation (mining metallurgical engineering, 35 (2015): 117-123), point Level the combined and staged magnetic separation of fine grinding (mining metallurgical engineering, 31 (2011): 36-39) and multi-stage magnetic separation associating multistage flotation (mining metallurgical engineering, 32 (2012): 62-66) etc..Long flow path and complexity due to these methods so that beneficiation cost is substantially increased;Simultaneously for such The high-silicon iron ore of type, above method there is also following shortcoming: owing to silicon dioxide gangue mineral is with superfine little granularity disperse Be embedded in iron mineral mutually in, it is necessary to mineral are milled to superfine granularity (less than 20 μm) it is possible to so that silicon dioxide stone-like pulse with Iron Ore Powder is separated thus obtains preferable desiliconization effect, and therefore iron loss is high.The defect of above-mentioned complex ore dressing flow process makes Blast furnace ironmaking use high-silicon iron ore the most uneconomical.
In addition to the Steel Production Flow Chart of blast furnace-converter, non-blast furnace ironmaking technology has obtained quick development in recent years.Its Middle rotary hearth furnace direct-reduction associating electric furnace melts division technique, and (i.e. FASTMELT, by MIDREX company of the U.S. and Japan's KOBE iron and steel public affairs Department's invention) and commercialized running more than 30 year (JOM, 63 (2001): 36-43;JOM, 65 (2003): 30-34).Burn with tradition Knot-blast furnace ironmaking flow process is compared, and FASTMELT technique is low to ingredient requirement, and various iron-bearing materials and carbon raw material may be used to The preparation of carbonaceous pelletizing;And rotary hearth furnace direct-reduction working condition is flexible, by adjusting carbonaceous pelletizing composition and controlling reduction Condition, can carry out accurate chemical composition to metallized pellet product and degree of metalization controls.
In blast furnace ironmaking, if SiO in sintering deposit2Too high levels, due to SiO in blast furnace2And the reaction (reaction between C 1), will make blast-melted in silicone content uncontrollable at reduced levels.From the behavior of silicon in blast furnace, if to ferrum In water, C content is controlled, it is possible to suppress silicon by slag to the migration of molten iron, such that it is able to the silicon efficiently controlled in molten iron Content.
(SiO2)+2C=2 [Si]+2CO (g) (1)
In FASMELT, rotary hearth furnace direct-reduction is main at present uses coal base carbonaceous pelletizing, and reducing agent is mainly coal dust or Jiao Powder.Owing to the gasification performance of coal dust or coke powder is relatively low, in carbonaceous pelletizing must excess join carbon (carbon oxygen mol ratio be more than 1.0) and Molten degree of metalization (more than 80%) required stage by stage just can be obtained, therefore at higher reduction temperature (more than 1200 DEG C) Residual carbon content in metallized pellet product is higher, melting stage by stage subsequently, relates to the reaction mainly reaction (1-of carbon residue 2), therefore, the quality of FASMELT technique gained molten iron is little with blast-melted mass difference.If it is it is clear that directly sharp With conventional FASTMELT PROCESS FOR TREATMENT high-silicon iron ore, it is impossible to suppress silicon from slag to the migration of molten iron.
(FeO)+2C=2Fe+2CO (g) (2)
During molten point, the Si in molten iron and the FeO in slag can also have following reaction (3) to occur.
2 (FeO)+[Si]=[SiO2]+2Fe (3)
But, after slag sluicing system, above reaction (3) is the interfacial reaction between slag ferrum, and this interfacial reaction speed is existed by Si Ferrum liquid and FeO be the restriction of diffusion rate in slag, after especially in molten iron, silicone content is reduced to 0.15wt%, molten iron pretreatment Desiliconization difficulty is the biggest.Must extend between molten timesharing or use enhancements (such as stirring).Secondly refractory material is had by the FeO in slag Bigger corrosion function, extends and means between molten timesharing that molten point stove lining durability greatly shortens.
It addition, carbon residue more in metallized pellet exists, reaction between carbon and oxygen (reaction violent during molten point can be caused (2)), simultaneously because the quick consumption of ferrous oxide in slag, the ferrous oxide content in slag is the lowest, so that slag viscosity liter High, it is easy to form foamed slag.Therefore melt slag ferrum during dividing to mix seriously, it is impossible to realize the sharp separation of slag ferrum.Needs add Adding extra flux carrying out slag (such as magnesium oxide), these measures make the quantity of slag of the ton ferrum of molten point process increase and technique mistake Journey complicates.
From the point of view of the part of test results of the present inventor, use the FASTMELT technique that coal-based direct reduction+high temperature melting divides Such high-silicon iron ore of route processing, after the molten metallized pellet dividing degree of metalization to be 90%, the silicon in the metallic iron of final gained contains Amount is 0.5~1.5wt%, and gained ferrum sample poor quality, wherein contains more field trash and pore.It is to say, use Coal-based direct reduction, part SiO in metallized pellet stone-like pulse2It is reduced during molten point in entrance molten iron.Cannot be fitted Close the hot metal containing low silicon needed for pneumatic steelmaking.
In addition to coal dust and coke powder, biomass carbon is also a kind of reducing agent containing carbon rich, therefore can also be as directly also Former reducing agent.Biomass carbon is also referred to as charcoal, biological coke, is biomass high temperature (< 700 under anaerobic or nearly anaerobic state DEG C) the carbon rich material matter of first stability that pyrolysis charring produces, it is mostly powdered granule.The raw material preparing biomass carbon is mainly agriculture The crop produced in industry activity and forest stubble, wood-curing waste etc..Such as straw charcoal, corn cob charcoal, rice straw charcoal, bamboo charcoal, wood Charcoal etc..China is a large agricultural country, and the raw material sources of biomass carbon are quite varied and cheap, in addition its production technology phase To simply, easily realize industrialization and produce (Scientia Agricultura Sinica, 46 (2013): 3324-3333).The present invention also contributes to China Effective utilization of huge agriculture waste resource.Biomass carbon is used to prepare carbonaceous pelletizing at CO2In/CO mixed atmosphere directly also Former.Compared with coal or coke, there is following advantage in part biological matter charcoal: [1] .CO2Under the conditions of gasification reaction (4) gasification Start temperature low;[2]. under high temperature (more than 800 DEG C), to reaction (4), biomass carbon has preferably gasification than coal dust or coke powder Performance.
C+CO2(g)=2CO (g) (4)
Feature based on the above biomass carbon, the present inventor proposes to use biomass carbon to make direct-reduction reducing agent, Use the process route of FASTMELT PROCESS FOR TREATMENT high-silicon iron ore.Particularly as follows: initially with prepared by suitable biomass carbon containing Carbon pellets;Secondly, under suitable reducing condition, obtained the metallized pellet of extremely low carbon residue by rotary hearth furnace direct-reduction;? After, low carbon residue metallized pellet directly obtains low carbon low silicon molten steel by high temperature slag sluicing system.In high temperature sludge ferrum separation process, Owing to the residual carbon content of metallized pellet is low, SiO in therefore can suppressing stone-like pulse mutually2Reduction, molten point of product of gained is low silicon Low-carbon (LC) molten steel.Meanwhile, in metallized pellet, the FeO of a small amount of residual can form FeO-SiO stage by stage molten2The slag system of-CaO, It is effectively reduced the viscosity of slag, promotes that slag ferrum is quickly completely separated and reduces the field trash in gained molten steel.Be conducive to improving steel The cleanliness factor of water.
Summary of the invention
It is an object of the invention to provide and a kind of efficiently utilize the method for difficult high-silicon iron ore resource i.e. from high-silicon iron ore The method directly preparing molten steel.The present invention is primarily directed to Iron grade more than 55wt% and SiO2The content high silicon more than 10wt% Iron mine.The present invention intends using cheap biomass carbon to prepare carbonaceous pelletizing+CO2/ CO mixed atmosphere direct-reduction+high temperature slag sluicing system Technology path.In the present invention, the raising of biomass carbon gasification performance is to use suitable preparation condition, containing biomass carbon pelletizing Can obtain the metallized pellet of low carbon residue after rotary hearth furnace is reduced directly, the metallized pellet of low carbon residue is divided by high temperature sludge ferrum again Low carbon low silicon molten steel is directly obtained after from.
For achieving the above object, the present invention is by the following technical solutions:
A kind of method directly preparing molten steel from high-silicon iron ore, said method comprising the steps of:
Step one, the preparation of biomass carbon, completely cut off abandoned biomass air thermal dissociation under the conditions of 300-500 DEG C and make life Material charcoal, gained biomass carbon is through ball milling beading shape charcoal powder;
Step 2, mineral aggregate are broken, and high-silicon iron ore is prepared as breeze;
Prepared by step 3, pelletizing, breeze, biomass charcoal powder and CaO are sufficiently mixed according to default ratio, adds certain Pelletizing is made after the organic binder bond of ratio and water;
Step 4, pelletizing are dried, by the driest for prepared pelletizing;
Step 5, direct-reduction, according to rotary hearth furnace direct-reduction technique, by dried pelletizing at CO and CO2Mixing is also Reduce under Primordial Qi atmosphere;
Step 6, high temperature melting divide, high temperature slag sluicing system, directly obtain molten steel.
Further, in described step one, the fixed carbon content of prepared biomass charcoal powder is more than 60wt%, volatile matter Content is more than 30wt%, and content of ashes is less than 5wt%, and the granularity of acinous biomass charcoal powder is less than 80 μm, at 1000 DEG C and CO2 Dividing potential drop is more than under conditions of 0.5atm, and granularity is gasified totally in 10 minutes less than this powdered carbon of 80 μm.
Further, in described step 2, all iron content of described high-silicon iron ore is more than 55wt%, and dioxide-containing silica is big In 10wt%;Described powder particle size is less than 80 μm.
Further, in described step 3, when breeze and biomass charcoal powder mix, fixed carbon in biomass charcoal powder Mol ratio (m with the oxygen in iron oxides in breezeC/mO) in the range of 0.70-0.80.
Further, in described step 3, the CaO percentage by weight in described pelletizing and SiO after interpolation CaO2Weight Ratio (the CaO wt%/SiO of percentage ratio2Wt%) it is 1.0-2.0.
Further, in described step 3, the organic adhesive dosage used in the process of ball processed is less than 2%, and water used contains Amount is less than 10%.
Further, in described step 4, baking temperature is 200-300 DEG C, and drying time is 2-3h.
Further, in described step 5, reduction temperature is 1100-1200 DEG C, and the recovery time is 15-20min;Reducing gases CO and CO in atmosphere2Intrinsic standoff ratio PCO2/PCOIt is 1.0.In the metal pelletizing obtained after carrying out reduction, degree of metalization is more than 80%, Residual carbon content is less than 1.0wt%.
Further, in described step 6, molten point temperature 1550-1600 DEG C that high temperature melting divides, 5-10min between molten timesharing, Atmosphere is N2Or noble gas.Gained steel quality meets or exceeds pneumatic steelmaking tapping standard.
The invention has the beneficial effects as follows:
[1]. biomass charcoal source is the agricultural biomass garbage of wide material sources, and its pyrolytical condition is easily controlled.Have Biomass easily prepare the biomass carbon of high gasification property.
[2]. owing to the content of ashes of biomass carbon is low, high temperature melting divides process ton scum amount few.Ash is brought into simultaneously Harmful element (sulfur and phosphorus) content is few.
[3]. equipment of direct reduction is rotary hearth furnace, and molten subset is that production equipment is iron and steel needed for electric arc furnace, the present invention Maximization ripe in industry produces equipment, with short production cycle, and efficiency is high.
[4]. carbonaceous pelletizing prepared by biomass carbon exists and there is easy efflorescence and the low problem of intensity in reduction process, at this In invention, owing to employing owes to join carbon technique, (C/O mol ratio is 0.7-0.8 and adds appropriate CaO, neutralizes in reduction process After reduction, the efflorescence of carbonaceous pelletizing is inhibited, and can keep enough intensity in pelletizing reduction process.
[5]. during molten point, in metallized pellet, the appropriate ferrous oxide of residual can effectively reduce the viscous of melting slag Degree, it is no longer necessary to extra slagging agent just can realize the preferable separating effect of slag ferrum.Gained molten iron inclusion content is few.
[6]. the high-quality molten steel of molten point of gained is conducive to the step of follow-up refine being greatly reduced and reducing energy consumption.Gained Molten steel is also conducive to manufacturing high added value steel products.
[7]. the present invention is simultaneously applicable to the direct steelmaking of general iron ore, has processed iron mineral quickly and efficiently.Keep away Exempt from the iron-making and steel-making flow process of conventional sintering-blast furnace-converter.
Accompanying drawing explanation
Fig. 1 is that the present invention utilizes biomass carbon to realize the process chart of high-silicon iron ore direct steelmaking;
Fig. 2 is biomass charcoal powder gasification performance (gasification condition: biomass charcoal powder maximum particle size prepared in embodiment one Less than 80 μm, abundant devolatilization and moisture at 1000 DEG C, gasification atmosphere is PCO/PCO2=1.0);
In Fig. 3: (a) is to be reduced directly in gained sample microsctructural photograph metallized pellet in embodiment one in the present invention The microscopic appearance of the breeze of breeze;B () is the microstructure of region A in (a);C () is the EDS power spectrum at (b) midpoint 1;(d) be The EDS power spectrum at (b) midpoint 2;
In Fig. 4: (a) is that in the present invention, in embodiment one, metallized pellet high temperature melting divides the microcosmic of rear gained typical metal sample Microscopic appearance;B () is the microstructure of region B in (a);C () is the EDS power spectrum at (b) midpoint 1;
Fig. 5 is the (gasification condition: coal dust maximum particle size is less than 80 μm, at 1000 DEG C of coal dust gasification performance used by embodiment five The most abundant devolatilization and moisture, gasification atmosphere is PCO/PCO2=1.0).
Detailed description of the invention
In order to make the purpose of the present invention, technical scheme and advantage clearer, below in conjunction with accompanying drawing 1-5 and enforcement Example, is explained in further detail the present invention.Should be appreciated that specific embodiment described herein is used only for explaining this Bright, it is not intended to limit the present invention.On the contrary, the present invention contains any spirit and scope in the present invention being defined by the claims On replacement, amendment, equivalent method and the scheme made.Further, in order to make the public that the present invention to be had a better understanding, below During the details of the present invention is described, detailed describe some specific detail sections.There is no this for a person skilled in the art The description of a little detail sections can also understand the present invention completely.
As it is shown in figure 1, a kind of method directly preparing molten steel from high-silicon iron ore, described method utilizes biomass carbon as containing Carbon pellets reducing agent, specifically includes following steps:
Step one, the preparation of biomass carbon: abandoned biomass completely cuts off air thermal dissociation under the conditions of 300-500 DEG C and makes biology Matter charcoal, gained biomass carbon is through ball milling beading shape charcoal powder.
In this step, in the biomass charcoal of gained, fixed carbon content is more than 30wt% more than 60wt%, volatile matter content, Ash is less than 5wt%;Through crushing and after ball milling, the granularity of acinous biomass charcoal powder is less than 80 μm.At 1000 DEG C and CO2Point Pressure is more than 0.5atm, and this biomass charcoal powder can be gasified totally in 10min.
Step 2, mineral aggregate are broken: taking high-silicon iron ore is raw material, and all iron content of described high-silicon iron ore is more than 55wt%, and two Silica content is more than 10wt%, is broken into acinous breeze with disintegrating machine and ball mill, and powder particle size is less than 80 μm.
Prepared by step 3, pelletizing: breeze and biomass charcoal powder are mixed according to certain ratio, then add a certain proportion of CaO, material after mixing adds a certain proportion of organic binder bond and water makes the pelletizing of a diameter of 10mm, and wherein, ball processed is viscous Knot agent uses organic binder bond, and the organic adhesive dosage used in the process of ball processed is less than 2%, and water content used is less than 10%.
In this step, when breeze and powdered carbon mix, in powdered carbon, fixed carbon is with iron oxides in breeze (predominantly Fe2O3Mol ratio (the m of the oxygen in)C/mO) approximate 0.70, belong to and owe to join carbon range, such as, the scope of this mol ratio is limited Between 0.70-0.80.The addition of CaO meets following condition: in the pelletizing of preparation in the percentage by weight of CaO and breeze SiO2The ratio (CaOwt%/SiO of percentage by weight2Wt%) it is 1.0-2.0.
Step 4, pelletizing are dried: in order to ensure the degree of drying of pelletizing, can by pelletizing after natural drying 24 hours, It is dried 2-3 hour under the conditions of 200-300 DEG C further, reaches fully to be dried.
Step 5, direct-reduction: the carbonaceous pelletizing prepared reduces under certain reducing condition.
In this step, in indication reducing condition, reduction temperature is 1100-1200 DEG C, and the recovery time is 15-20min, is passed through CO and CO2Gaseous mixture, reducing atmosphere keeps PCO2/PCOIt is equal or approximately equal to 1.0.In Direct Reduction, biomass carbon is same Time participate in previous reaction (4) and following reaction (5).
3C+Fe2O3=2Fe+3CO (g) (5)
Wherein, in direct-reduction early stage, biomass charcoal powder is mainly used in the direct-reduction of iron oxides in breeze and continuous Reduce (reaction (5));In the reduction later stage, along with in pelletizing, the degree of metalization of ferrum improves, the iron oxides consumption to biomass carbon Seldom, powdered carbon is mainly by the CO in surrounding atmosphere2Consume further and reduce (reaction (4)).Reduction later stage biomass carbon Gasification constantly consume while also prevent the reoxidizing, as shown in reaction (6) of metallic iron in pelletizing.In the direct-reduction later stage Breeze degree of metalization meeting fraction reduces but reduces the carbon residue in pelletizing the most further.Reducing latter stage, in metallized pellet Powdered carbon almost all consumes.
Fe+CO2(g)=FeO+CO (g) (6)
Step 6, high temperature melting divide: the pelletizing good by above-mentioned reduction, and in high temperature furnace, molten point realizes slag sluicing system.
In this step, the molten point condition that high temperature melting divides is molten point temperature 1550-1600 DEG C, 5-10min between molten timesharing, atmosphere For N2Or noble gas, to realize slag ferrum sharp separation.High temperature melting divides and directly obtains hot molten steel, wherein, and the silicon of hot molten steel Content is less than 0.05wt%, and carbon content is less than 0.05wt%, and the metallic iron response rate is more than 80%.The quality of hot molten steel has reached To pneumatic steelmaking tap time molten steel quality, after deoxidation, refine steel making working procedure can be directly entered.
Below in conjunction with specific embodiment, the method for the present invention is described in detail, high-silicon iron ore used by the embodiment of the present invention The chemical composition of powder is as shown in table 1.
Table 1 high-silicon iron ore chemical composition (wt%)
Embodiment one
[1]. prepared by biomass carbon: discarded Fructus Jujubae timber is pyrolyzed carbonization at 400 DEG C, is prepared as biomass carbon.Gained is biological The Industrial Analysis result of matter charcoal is as shown in table 2.The gasification performance of gained biomass carbon is as shown in Figure 2.Prepared biomass carbon Through ball milling, its granularity is less than 80 μm.
The Industrial Analysis result (wt%) of biomass carbon used by table 2. embodiment one
[2]. mineral aggregate crushes: take above-mentioned high-silicon iron ore 500g, tentatively crushes and after abundant ball milling, its granularity is less than 80μm。
[3]. prepared by pelletizing: above-mentioned Iron Ore Powder and powdered carbon and a certain amount of CaO mixing.Wherein biomass carbon consumption is It is 0.8 that 122g, i.e. its amount meet the mol ratio of C/O in carbonaceous pelletizing.Wherein CaO addition meets CaOwt%/SiO2Wt%= 2.0.The pelletizing of a diameter of 10.0mm made by material after mixing.Ball binding agent processed uses the secondary stock of 2.0%.
[4]. pelletizing is dried: after pelletizing natural drying 24h, further at 300 DEG C of dry 2h.
[5]. direct-reduction: reduce in following condition: using tube furnace, reduction temperature is 1200 DEG C, and the recovery time is 15min, is passed through CO/CO2P in gaseous mixture 1L/min and gaseous mixtureCO2/PCO=1.0.With simulation furnace atmosphere as PCO2/PCO= 1.0.The degree of metalization of the metal pelletizing obtained after carrying out reduction is 88%, and metallized pellet residual carbon content is 0.90wt%.Institute Obtain shown in microscopic appearance such as Fig. 3 (a) of metallized pellet, after reduction shown in the microstructure of breeze such as Fig. 3 (b).By Fig. 3 (b) Middle EDS energy spectrum analysis (Fig. 3 (c-d)) is it can be seen that short grained quartz is still embedded in metallic iron.
[6]. slag sluicing system: the pelletizing that will have reduced, melts in Si-Mo rod high temperature box furnace and divides.Molten point temperature is 1550 DEG C, it is respectively 5min and 10min between molten timesharing, it is achieved slag sluicing system.
When being 5min between molten timesharing, gained metal-like impurity content is [%C]: 0.02wt%, [%Si]: 0.02wt%, [%Mn]: < 0.01wt%, [%S]: 0.02wt%, [%P]: < 0.01wt%, [%O]: 0.178wt%, [% N]: 0.045wt%;Metal recovery rate 90%.Visible, the content of carbon, silicon, manganese, sulfur and the phosphorus of gained ferrum sample has reached The standard of converter tapping.Shown in gained metalloid microscopic appearance such as Fig. 4 (a), the microstructure of field trash such as Fig. 4 in metal-like Shown in (b).By the EDS energy spectrum analysis (Fig. 4 (c)) of Fig. 4 (b) it can be seen that in gained metal-like, field trash is less and granularity very Little.This represents that gained metal-like has good cleanliness factor.
When being 10min between molten timesharing, gained metal-like impurity content is [%C]: 0.036wt%, [%Si]: 0.03wt%, [Mn]: < 0.01wt%, [%S]: 0.02wt%, [%P]: < 0.01wt%, [%O]: 0.168wt%, [%N]: 0.049wt%;Metal recovery rate 89%.Visible, the content of carbon, silicon, manganese, sulfur and the phosphorus of gained ferrum sample has reached converter The standard of tapping.
Embodiment two
[1]. prepared by biomass carbon: with embodiment one.
[2]. mineral aggregate crushes: take above-mentioned high-silicon iron ore 500g, tentatively crushes and after abundant ball milling, its granularity is less than 80μm。
[3]. prepared by pelletizing: above-mentioned Iron Ore Powder and powdered carbon and a certain amount of CaO mixing.Wherein biomass carbon consumption is It is 0.8 that 122g, i.e. its amount meet the mol ratio of C/O in carbonaceous pelletizing.Wherein CaO addition meets CaOwt%/SiO2Wt%= 1.0.The pelletizing of a diameter of 10.0mm made by material after mixing.Ball binding agent processed uses the secondary stock of 2.0%.
[4]. pelletizing is dried: after pelletizing natural drying 24h, further at 300 DEG C of dry 2h.
[5]. direct-reduction: reduce in following condition: using tube furnace, reduction temperature is 1100 DEG C, and the recovery time is 20min, is passed through CO/CO2P in gaseous mixture 1L/min and gaseous mixtureCO2/PCO=1.0.With simulation furnace atmosphere as PCO2/PCO= 1.0.The degree of metalization of the metal pelletizing obtained after carrying out reduction is 84%, and metallized pellet residual carbon content is 0.33wt%.
[6]. slag sluicing system: the pelletizing that will have reduced, melts in Si-Mo rod high temperature box furnace and divides.Molten point temperature is 1550 DEG C, it is respectively 5min and 10min between molten timesharing, it is achieved slag sluicing system.
When being 5min between molten timesharing, each constituent content of gained metal-like is [%C]: 0.046wt%, [%Si]: 0.02wt%, [%Mn]: < 0.01wt%, [%S]: 0.03wt%, [%P]: < 0.01wt%, [%O]: 0.252wt%, [% N]: 0.039wt%;Metal recovery rate 84%.Visible, the content of carbon, silicon, manganese, sulfur and the phosphorus of gained ferrum sample has reached The standard of converter tapping.
When being 10min between molten timesharing, each constituent content of gained metal-like is [%C]: 0.016wt%, [%Si]: 0.04wt%, [%Mn]: < 0.01wt%, [%S]: 0.02wt%, [%P]: < 0.01wt%, [%O]: 0.137wt%, [% N]: 0.055wt%.Metal recovery rate 83%.Visible, the content of carbon, silicon, manganese, sulfur and the phosphorus of gained ferrum sample has reached The standard of converter tapping.
Embodiment three
[1]. prepared by biomass carbon: with embodiment one.
[2]. mineral aggregate crushes: take above-mentioned high-silicon iron ore 500g, tentatively crushes and after abundant ball milling, its granularity is less than 80μm。
[3]. prepared by pelletizing: above-mentioned Iron Ore Powder and powdered carbon and a certain amount of CaO mixing.Wherein biomass carbon consumption is It is 0.7 that 107g, i.e. its amount meet the mol ratio of C/O in carbonaceous pelletizing.Wherein CaO addition meets CaOwt%/SiO2Wt%= 2.0.The pelletizing of a diameter of 10.0mm made by material after mixing.Ball binding agent processed uses the secondary stock of 2.0%.
[4]. after pelletizing natural drying 24h, further at 300 DEG C of dry 2h.
[5]. direct-reduction: reduce in following condition: using tube furnace, reduction temperature is 1200 DEG C, and the recovery time is 15min, is passed through CO/CO2P in gaseous mixture 1L/min and gaseous mixtureCO2/PCO=1.0.With simulation furnace atmosphere as PCO2/PCO= 1.0.The degree of metalization of the metal pelletizing obtained after carrying out reduction is 84%, and metallized pellet residual carbon content is 0.28wt%.
[6]. slag sluicing system: the pelletizing that will have reduced, melts in Si-Mo rod high temperature box furnace and divides.Molten point temperature is 1550 DEG C, it is 10min between molten timesharing, it is achieved slag sluicing system.
The each constituent content of gained metal-like is [%C]: 0.026wt%, [%Si]: 0.02wt%, [%Mn]: < 0.01wt%, [%S]: 0.03wt%, [%P]: < 0.01wt%, [%O]: 0.193wt%, [%N]: 0.056wt%;Metal The response rate 81%.Visible, the content of carbon, silicon, manganese, sulfur and the phosphorus of gained ferrum sample has reached the standard of converter tapping.
Embodiment four
[1]. prepared by biomass carbon: with embodiment 1.
[2]. mineral aggregate crushes: take above-mentioned high-silicon iron ore 500g, tentatively crushes and after abundant ball milling, its granularity is less than 80μm。
[3]. prepared by pelletizing: above-mentioned Iron Ore Powder and powdered carbon and a certain amount of CaO mixing.Wherein biomass carbon consumption is It is 0.7 that 107g, i.e. its amount meet the mol ratio of C/O in carbonaceous pelletizing.Wherein CaO addition meets CaOwt%/SiO2Wt%= 1.0.The pelletizing of a diameter of 10.0mm made by material after mixing.Ball binding agent processed uses the secondary stock of 2.0%.
[4]. after pelletizing natural drying 24h, further at 300 DEG C of dry 2h.
[5]. direct-reduction: reduce in following condition: using tube furnace, reduction temperature is 1100 DEG C, and the recovery time is 20min, is passed through CO/CO2P in gaseous mixture 1L/min and gaseous mixtureCO2/PCO=1.0.With simulation furnace atmosphere as PCO2/PCO= 1.0.The degree of metalization of the metal pelletizing obtained after carrying out reduction is 82%, and metallized pellet residual carbon content is 0.10wt%.
[6]. slag sluicing system: the pelletizing that will have reduced, melts in Si-Mo rod high temperature box furnace and divides.Molten point temperature is 1550 DEG C, it is 10min between molten timesharing, it is achieved slag sluicing system.
It is [%C]: 0.018wt% that gained obtains each constituent content of metal-like, [%Si]: 0.02wt%, [%Mn]: < 0.01wt%, [%S]: 0.01wt%, [%P]: < 0.01wt%, [%O]: 0.164wt%, [%N]: 0.037wt%;Metal The response rate 80%.Visible, the content of carbon, silicon, manganese, sulfur and the phosphorus of gained ferrum sample has reached the standard of converter tapping.
Comparative example five
[1]. reducing agent uses coal dust, its composition such as following table.Coal dust is through ball milling, and its granularity is less than 80 μm;Its gasification property Can be as shown in Figure 5.
The composition (wt%) of coal dust in table 5. embodiment five
[2]. carbonaceous pelletizing preparation meets C/O=1.0, i.e. takes coal dust 120g;Direct-reduction temperature used is 1200 DEG C, The direct-reduction time is 20min.
[3]. remaining step is with embodiment one.The residual carbon content of gained metallized pellet is 2.8wt%, and degree of metalization is 93%.
The molten point each constituent content of gained metal-like is [%C]: 1.05wt%, [%Si]: 0.55wt%, [%S]: 0.11wt%;Metal recovery rate 97%.Metallic iron sample quality is less than the standard of converter tapping molten steel, and in molten iron, [%Si] is beyond height The standard of stove molten iron.
Comparative example six
[1]. biomass carbon used is identical with embodiment one;
[2]. carbonaceous pelletizing preparation meets C/O=0.9, i.e. takes biomass charcoal powder 137g.
[3]. remaining step is with embodiment one.The degree of metalization of reduction gained metallized pellet is 91%, and wherein carbon residue contains Amount is 1.17wt%.
The molten point each constituent content of gained metal-like is [%C]: 0.13wt%, [%Si]: 0.17wt%, [%S]: 0.02wt%;Metal recovery rate 94%.Metallic iron sample quality is less than the standard of converter tapping molten steel, higher than blast-melted mark Accurate.
Although an embodiment of the present invention has been shown and described, for the ordinary skill in the art, permissible Understand and these embodiments can be carried out multiple change without departing from the principles and spirit of the present invention, revise, replace And modification, the scope of the present invention is limited by claims and equivalent thereof.

Claims (9)

1. the method directly preparing molten steel from high-silicon iron ore, it is characterised in that said method comprising the steps of:
Step one, the preparation of biomass carbon, completely cut off abandoned biomass air thermal dissociation under the conditions of 300-500 DEG C and make biomass Charcoal, gained biomass carbon is through ball milling beading shape powdered carbon;
Step 2, mineral aggregate are broken, and high-silicon iron ore is prepared as breeze;
Prepared by step 3, pelletizing, breeze, biomass charcoal powder and CaO are sufficiently mixed according to default ratio, adds certain proportion Organic binder bond and water after make pelletizing;
Step 4, pelletizing are dried, by the driest for prepared pelletizing;
Step 5, direct-reduction, according to rotary hearth furnace direct-reduction technique, by dried pelletizing at CO and CO2Mixing reducing atmosphere Under reduce;
Step 6, high temperature melting divide, high temperature slag sluicing system, directly obtain molten steel.
The method that the most according to claim 1, high-silicon iron ore directly prepares molten steel, it is characterised in that: in described step one, institute The fixed carbon content of the biomass charcoal powder of preparation is more than 30wt% more than 60wt%, volatile matter content, and content of ashes is less than 5wt%;Carefully The granularity of granular biomass charcoal powder is less than 80 μm;At 1000 DEG C and CO2Dividing potential drop is more than under conditions of 0.5atm, and granularity is less than 80 μm This powdered carbon be gasified totally in 10 minutes.
The method that the most according to claim 1, high-silicon iron ore directly prepares molten steel, it is characterised in that: in described step 2, institute The all iron content stating high-silicon iron ore is more than 10wt% more than 55wt%, dioxide-containing silica;Described powder particle size is less than 80 μm.
The method that the most according to claim 1, high-silicon iron ore directly prepares molten steel, it is characterised in that: in described step 3, ore deposit When powder and biomass charcoal powder mix, the mol ratio (m of the oxygen in iron oxides in fixed carbon and breeze in biomass charcoal powderC/ mO) in the range of 0.70-0.80.
The method that the most according to claim 1, high-silicon iron ore directly prepares molten steel, it is characterised in that: in described step 3, add CaO percentage by weight in described pelletizing and SiO after adding CaO2The ratio (CaOwt%/SiO of percentage by weight2Wt%) it is 1.0- 2.0。
The method that the most according to claim 1, high-silicon iron ore directly prepares molten steel, it is characterised in that: in described step 3, system Organic adhesive dosage used in the process of ball is less than 2%, and water content used is less than 10%.
The method that the most according to claim 1, high-silicon iron ore directly prepares molten steel, it is characterised in that: in described step 4, institute The baking temperature preparing pelletizing is 200-300 DEG C, and drying time is 2-3h.
The method that the most according to claim 1, high-silicon iron ore directly prepares molten steel, it is characterised in that: in described step 5, also Former temperature is 1100-1200 DEG C, and the recovery time is 15-20min, CO and CO in atmosphere2Intrinsic standoff ratio PCO2/PCOIt is 1.0, gained The degree of metalization of metallized pellet is more than 80%, and residual carbon content is less than 1.0wt%.
The method that the most according to claim 1, high-silicon iron ore directly prepares molten steel, it is characterised in that: in described step 6, high The molten point temperature of molten point of temperature is 1550-1600 DEG C, is 5-10min between molten timesharing, and atmosphere used is N2Or noble gas, gained steel Water quality meets or exceeds pneumatic steelmaking tapping standard.
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