CN104862440A - Low-grade iron ore direct reduction method - Google Patents

Low-grade iron ore direct reduction method Download PDF

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Publication number
CN104862440A
CN104862440A CN201510122728.6A CN201510122728A CN104862440A CN 104862440 A CN104862440 A CN 104862440A CN 201510122728 A CN201510122728 A CN 201510122728A CN 104862440 A CN104862440 A CN 104862440A
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coal
iron ore
low
grade iron
grade
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黄柱成
邹军
姜涛
范晓慧
李光辉
郭宇峰
张元波
杨永斌
姚圣杰
钟荣海
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Qidong Shunda Mining Co Ltd
Central South University
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Qidong Shunda Mining Co Ltd
Central South University
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00Technologies related to metal processing
    • Y02P10/20Recycling

Abstract

The invention relates to a low-grade iron ore direct reduction method, which comprises: calculating and taking a certain amount of coal powder, an additive, a binder and water by adopting the dry basis mass of iron ore to be treated as reference; uniformly mixing the taken components, and completely wetting to obtain an internal matching coal; uniformly mixing the internal matching coal and iron ore particles to be treated, and granulating to obtain granulated pellets; directly conveying the obtained granulated pellets into a rotary kiln, carrying out drying, pre-heating, and reduction roasting to carry out coal base direct reduction so as to obtain a reduced material, cooling the reduced material in the absence of air, and carrying out dry magnetic separation to obtain the reduced roasting pellets and the residual carbon; and carrying out treatments such as ore grinding and magnetic separation on the reduced roasting pellets to obtain iron concentrate, or carrying out re-grinding and re-magnetic separation to obtain the reduced iron powder, wherein the obtained residual carbon can be recycled. With the method of the present invention, the low-grade iron ore can be effectively treated, the internal matching coal and the additive are used to granulate, the wet pellets enter the kiln, the coal base direct reduction is performed, the magnetic separation is performed to obtain the high-grade iron concentrate or the directly-reduced iron powder, and the method has characteristics of energy saving, high efficiency, and rapidness.

Description

A kind of method of low-grade iron ore direct-reduction
Technical field
The present invention relates to a kind of method of low-grade iron ore direct-reduction, particularly in a kind of low-grade iron ore, coal blending and additive granulation wet bulb enter kiln coal-based direct reduction-magnetic selection method.
Background technology
Along with the fast development of Iron And Steel Industry, China's iron and steel output rises year by year, domestic high-quality ferrolite supply is not enough, and problem is day by day serious, Mineral resources have become " bottleneck " of restriction China development of iron & steel industry, the demand of China iron deposit stone sharply increases, 2009 so far Chinese imported Fe ore amount increase by 21.8% every year, constantly riseing of import volume, also the importation dependence of China iron deposit stone is made to improve constantly, 2012, China iron deposit stone importation dependence is about 63%, and within 2014, external importation dependence is elevated to 78.5% once again.The immense pressure that coke resource faces simultaneously seriously governs the development of Iron industry.Coal resources in China mass discrepancy is large, bituminous coal, hard coal large percentage, and coking coal only accounts for about 27% of coal reserves, and skewness, very unfavorable to blast furnace ironmaking production development.Coal-based direct reduction is main energy sources with coal, is the flow process using rotary kiln as main equipment, and rotary kiln for directly reducing technology has been tending towards ripe, and the gentle equipment operation ability of throughput, scale, operating rate, Automated water all grows a lot [1-4].But rotary kiln technology exists long flow path, investment is large, overall energy consumption is high, pelletizing is long at kiln residence time, easily produces low temperature reduction degradation, and it is on the low side that kiln holds utilization coefficient, and in kiln, amount of powder is large, and the problem of the aspects such as the easy ring formation of rotary kiln, still needs perfect further.
China iron deposit stone resource is rich and not rich, in about 58,100,000,000 t reserves (occupying the 4th, the world), 97% is lean ore, average grade is 33%, lower than World Iron ore average grade 11 percentage points, the rich ore that Iron grade is greater than 50% only accounts for 2.7%, and (about 1,500,000,000 t), and most iron ore must can enter stove and smelt after beneficiation enrichment.The technique of preparing of ferric oxide ore is selected still not have breakthrough for complicated difficults such as the rhombohedral iron ore that the embedding cloth of the granularity accounting for total reserves more than 25% is thin, gangue is mainly quartz and Iron-containing silicate and low-grade limonites.Adopt the method process low grade ore of direct-reduction-magnetic separation to be the direction of current primary study, at reduction temperature 1100 DEG C ~ 1200 DEG C, reduce 90min ~ 120min, Iron grade and the concentrate of the rate of recovery all more than 90% can be obtained [5-7], can effectively process fine grain teeth cloth rhombohedral iron ore.But, because low-grade iron ore contains a large amount of gangue minerals (as SiO 2deng), a large amount of fayalite liquid phase can be produced in the temperature range of 1100 DEG C ~ 1200 DEG C, the direct motion that direct-reduction is produced is produced serious influence, and energy consumption is high, the recovery time is long, still rests on laboratory stage at present.The present invention effectively can utilize low-grade iron ore, and in adopting, coal blending concentrates strenuous primary treatment granulation wet bulb to enter kiln to carry out coal-based direct reduction, and magnetic separation obtains high-grade iron ore concentrate or direct-reduction iron powder, have energy-conservation, efficiently, feature fast.
Reference:
[1]Schnabel W,Schlebusch D,Elsenheimer G.SL/RN coal-based direct reduction-the state of theart[J].Ironmaking Proc.,Metall.Soc.AIME,1983,42(1):163-170.
[2] experience [J] of 9 years produced by Bornman C.J. South Africa SL/RN sponge iron. agglomerates of sintered pellets, 1994, (2): 42-43.
[3] Zhao Jianhong, Lv Zhenhua. domestic coal-based rotary kiln direct-reduction technique and device commentary [J]. Shanxi is metallurgical, and 2002,86 (2): 1-4.
[4] Xu Xiaojie, Bao Xiangjun, Zhao Peng. China's coal-based direct reduction iron current situation and prospect [J]. the 7th China Steel nd Annual Meeting collection, 2009.316-320.
[5] Zhu Deqing, Deng Xiulan, the spring iron army, etc. certain fine-grained dissemination lean hematite ore direct-reduction-low intensity magnetic separation test [J]. metal mine, 2012 (2): 60-62,66.
[6] Wei Yuxia, Sun Tichang, Kou Jue, etc. interior coal blending consumption is on the impact [J] of certain refractory iron ore briquetting direct-reduction roasting. Central South University's journal (natural science edition), 2013.44 (4): 1305-1311.
[7] Xu Bin, Zhuan Jianming, Bai Guohua, etc. the research of low-grade iron ore coal-based direct reduction. [J] mineral products fully utilize, and 2001 (06): 20-24.
Summary of the invention
The object of the invention is a kind of method being to develop low-grade iron ore direct-reduction, effectively can solve low-grade iron ore to be difficult to effectively to utilize and in coal-based DR process, reduction temperature is high, the recovery time long, easily ring formation and high in cost of production problem, thus effectively reduce enterprise's production cost, effectively can alleviate the development of high-quality iron ore deposit situation in short supply and promotion China's steel industry.
The method of a kind of low-grade iron ore direct-reduction of the present invention, comprises the following steps:
Step one
Using pending low-grade iron ore butt quality for benchmark gets coal dust, additive, binding agent and water as interior coal blending pretreating raw material with joining;
Wherein,
Coal dust is 0.2 ~ 0.4 join and get by C/Fe mass ratio; In described coal grain, the butt quality that granularity is less than the coal dust of 0.074mm accounts for more than 45% of coal dust butt total mass;
Pending the joining by 2.0% ~ 5.0% of low-grade iron ore butt quality of additive is got, and described additive is selected from NaCl, CaCl 2, FeCl 3, Na 2cO 3in at least one, be preferably NaCl, CaCl 2, FeCl 3in at least one, more preferably NaCl;
Binding agent is joined by 0.5% ~ 2.0% of pending low-grade iron ore butt quality and is got, and described binding agent is selected from least one in wilkinite, composite bentonite, more preferably wilkinite;
Water is joined by 6.0% ~ 7.0% of pending low-grade iron ore butt quality and is got;
Step 2
Step one is joined coal blending pretreating raw material-coal dust, additive, binding agent and water in getting to carry out being mixed to the fully wetting and additive of pulverized coal particle and penetrate in coal particle hole and crack under water function, obtain pretreated interior coal blending;
Step 3
After pretreated for step 2 gained interior coal blending is mixed with pending low-grade iron ore particle, adopt disk or drum polletizing, obtain the granulation bead that diameter is 3 ~ 8mm; In described granulation bead, the mass percentage of water is 8% ~ 12%; In described pending low-grade iron ore particle, the butt quality that granularity is less than 0.074mm particle accounts for more than 70% of pending low-grade iron ore butt total mass;
Step 4
Directly sent in rotary kiln by step 3 gained granulation bead, drying, preheating, coal-based direct reduction calcination process, obtain reducing material, and reducing material obtains reducing roasting bead and carbon residue through dry magnetic separation after cooling under the condition of isolated air; The temperature of described coal-based direct reduction calcination process is 920 DEG C ~ 980 DEG C;
Step 5
After little for the reducing roasting of step 4 gained ball warp ore grinding, magnetic separation process, obtain iron ore concentrate;
Or
By little for the reducing roasting of step 4 gained ball warp ore grinding, magnetic separation process, regrinding and reconcentration, obtain reduced iron powder.
The method of a kind of low-grade iron ore direct-reduction of the present invention, in step one, the fugitive constituent of described coal dust is more than or equal to 25%; Fixed carbon content is more than or equal to 45%.
The method of a kind of low-grade iron ore direct-reduction of the present invention, in step one, described coal dust is selected from least one in brown coal, hard coal, biomass carbon.
The method of a kind of low-grade iron ore direct-reduction of the present invention, in described pending low-grade iron ore, the mass percentage of iron is more than or equal to 28%.
The method of a kind of low-grade iron ore direct-reduction of the present invention, in step 3, pending low-grade iron ore particle is obtained by ore grinding process, and described ore grinding process is selected from the one in profit mill, high pressure roller mill, thunder mill.
The method of a kind of low-grade iron ore direct-reduction of the present invention, in step 3, described granulation bead adopts disk or drum pelletizer to make.
The method of a kind of low-grade iron ore direct-reduction of the present invention, the Pulverization ratio being less than 1mm in step 3 after gained granulation bead high temperature drying and preheating is less than or equal to 5%.Described Pulverization ratio is recorded by following method, gets granulation bead 500g with wet bulb at logical N 2dry under 800 DEG C of conditions in the retort furnace of protection, the dried pellet of acquisition, makes it be that 0.5m falls from height, and after repeating 3 times, the quality that weighing granularity is less than or equal to the powder of 1.0mm is Ag, described Pulverization ratio=A/500.
The method of a kind of low-grade iron ore direct-reduction of the present invention, in step 4, the time of reducing roasting process is 20min ~ 45min.
In order to reach better implementation result, the behaviour of step 4 does and can be preferably: sent into by step 3 gained granulation bead in rotary kiln, under 500 DEG C ~ 920 DEG C high-temperature gas effects of rotary kiln afterbody, carry out drying, intensification and preheating, temperature is elevated to 920 DEG C from normal temperature, and the time is 60min ~ 90min; Reducing material is made again at 920 DEG C ~ 980 DEG C coal-based direct reduction roasting 20min ~ 45min; Reducing material completely cuts off air cooling to 90 DEG C ~ 110 DEG C by the cooling drum of outside water spray, adopts dry magnetic separation to be separated and obtain reducing roasting bead and carbon residue after cooling.During described dry magnetic separation, magneticstrength is 1.0 ~ 1.2KA/m.
The method of a kind of low-grade iron ore direct-reduction of the present invention, in step 4, gained carbon residue can be used as coal dust raw material in step one.
The method of a kind of low-grade iron ore direct-reduction of the present invention, in step 4, the degree of metalization of gained reducing roasting bead is 60% ~ 85%.Relative to degree of metalization 30% ~ 40 of the prior art, improve 1.5-2.8 doubly.Described prior art, what it was representative is " a kind of method that low-grade iron ore is upgrade " (application number or the patent No. are 201410200461).
The method of a kind of low-grade iron ore direct-reduction of the present invention, the embodiment of step 5 is: after mass percentage step 4 gained reducing roasting bead ore grinding to granularity being less than or equal to 0.074mm equals to be greater than 95% of reducing roasting bead total mass, adopt magnetic separation, during magnetic separation, magneticstrength is 1.4 ~ 2.0KA/m.In order to improve grinding efficiency, in step 5, generally by ore grinding time controling at 10min ~ 20min.
The method of a kind of low-grade iron ore direct-reduction of the present invention, in step 5, the grade of described iron ore concentrate is more than or equal to 70.95%, is preferably greater than and equals 74.33%, is more preferably more than or equal to 80.19%, is further preferably greater than and equals 83%.
Principle and advantage
By groping repeatedly, contriver finds that interior coal blending concentrates strenuous primary treatment to be gordian technique means of the present invention, not only enhance ferriferous oxide and fixed carbon carries out direct reduction reactor process, is the key measures that wet bulb enters kiln coal-based DR process simultaneously.Concentrate in strenuous primary treatment process in interior coal blending, coal and additive NaCl soak and among the crackle that penetrates into coal and hole under moisture fully acts on, in coal-based direct reduction roasting process subsequently, enhance fixed carbon and ferriferous oxide fast restore reacts, and effectively strengthen growing up of metallic iron crystal grain; What produce in 920 DEG C ~ 980 DEG C reducing roasting 20min ~ 45min processes in rotary kiln consumes partial fixing carbon and generates carbon residue, and these carbon residues have flourishing hole and good reactive behavior, the low temperature of this favourable whole reduction reaction, carries out fast.In addition, the carbon residue generated can as reductive agent Returning utilization after concentrating intensive treatment by additive and moisture.Carbon residue is stripped of moisture and micromolecular hydrocarbon polymer (substantially not participating in reduction reaction in reduction process) simultaneously, is conducive to improving granulation bead pellet strength in drying and temperature-rise period, reduces Decrepitation Phenomena.Adding of binding agent, under the strengthening effect of appropriate additive and suitable quantity of water, change the surface property of coal, coal particle surface and internal fissure is made to become hydrophilicity by hydrophobic, improve the balling property of compound, in heating reduction process, serve the effect of the thermostability improving coal, effectively reduce in coal cracking or gasification producing fierce Decrepitation Phenomena, significantly improve the thermostability of interior coal blending granulation bead wet bulb.Component due to interior coal blending arranges rationally, interior coal blending and iron ore are arranged in pairs or groups suitably, this makes granulation bead (wet bulb) directly can enter kiln, and can bear 500 DEG C ~ 800 DEG C high temperature dryings and not produce powder, thus ensure that carrying out smoothly of rotary kiln for directly reducing.
Contriver is less than the mass percent of 0.074mm by effective control iron ore and coal particle size, charge calculation determines C/Fe mass ratio 0.2 ~ 0.4, the consumption of the content 2.0% ~ 5.0% of additive NaCl and binding agent and wetting water, by coal blending in pre-treatment, then interior coal blending mixed with iron ore and be granulation into granulation bead 3 ~ 8mm, under the comprehensive synergy of above-mentioned several factor, significantly improve the balling-up of coal blending in low-grade iron ore, thermostability and reductibility, the granulation bead obtained can realize wet bulb and directly enter kiln under lower reduction temperature, carry out coal-based middle temperature fast direct reducing, effectively avoid the lump ore recovery time long, ring formation of rotary kiln, the problems such as pelletizing centerand edge reduction lack of homogeneity, also can effectively avoid fine ore reduce poor air permeability, dust flies upward with hot waste gas affects equipment direct motion and cause the problems such as iron ore loss, the present invention simultaneously eliminates cylindrical drier, shortens technical process, improves thermo-efficiency.Effectively working in coordination with and controlling efficiently by each factor of the present invention, the present invention can realize coal blending and the coal-based middle temperature fast restore of additive granulation in low-grade iron ore at rotary kiln, only need at the temperature of 920 DEG C ~ 980 DEG C, recovery time is 20min ~ 45min, thus make most ferriferous oxide in iron ore, particularly be less than 0.010mm rhombohedral iron ore part fast restore and become metallic iron and rapid aggregation is grown up under Additive, and other gangue mineral does not change substantially or mineralising forms low melting point and can not hinder the reduction of ferriferous oxide, be conducive to the migration of metallic iron, merger is grown up, high-grade iron ore concentrate or direct-reduction iron powder is obtained after magnetic separation, have energy-conservation, efficiently, feature fast.
Adopt method of the present invention, when rotary kiln reduces, burning energy consumption mark coal is less than 120kg/t iron ore, far below conventional coal-based direct reduction rotary kiln energy consumption index.For raw material Iron grade be 28.81%, SiO 2content be 43.52% low-grade iron ore and reduction coal fixed carbon percentage composition be 55.83%, volatile matter percentage composition is 36.03%, adopt the present invention, the degree of metalization that can obtain reducing roasting bead nodulizing reaches more than 80%, can obtain reduced iron powder after can obtaining iron ore concentrate or regrinding and reconcentration after magnetic separation.In gained iron powder of the present invention the grade of iron be more than or equal to 83% and the rate of recovery of iron be greater than 70%.
Accompanying drawing explanation
Accompanying drawing 1 is process flow sheet of the present invention.
Embodiment
Below in conjunction with drawings and Examples, the invention will be further described.Wherein, to be Iron grade be raw material 28.81%, SiO 2content be 43.52% low-grade iron ore and reduction coal fixed carbon percentage composition be 58.38%, volatile matter percentage composition is 34.63%.
Comparative example 1
Taking granularity is 12 ~ 16mm low-grade iron ore 350g, be 0.8 join and get coal dust by C/Fe mass ratio, after iron ore and coal dust are mixed, load in Rotary tube furnace and to be elevated to 950 DEG C from normal temperature, the time of heating up is 60min, carries out coal-based direct reduction roasting 35min after being warming up to 950 DEG C; Reducing roasting ore deposit is 50% through ball milling 20min, ore milling concentration, and magneticstrength is 1.2KA/m magnetic separation; The rate of recovery obtaining result magnetic separation of iron ore concentrate is 62.53%, and concentrate grade is 46.52%.
Comparative example 2
Taking granularity is 1 ~ 3mm low-grade iron ore 350g, be 0.5 join and get coal dust by C/Fe mass ratio, after iron ore and coal dust are mixed, load in Rotary tube furnace and to be elevated to 950 DEG C from normal temperature, the time of heating up is 60min, carries out coal-based direct reduction roasting 35min after being warming up to 950 DEG C; Reducing roasting ore deposit is 50% through ball milling 20min, ore milling concentration, and magneticstrength is 1.4KA/m magnetic separation; The rate of recovery obtaining result magnetic separation of iron ore concentrate is 64.78%, and concentrate grade is 49.38%.
Comparative example 3
Take granularity for being less than 1mm low-grade iron ore 350g, be 0.5 join and get coal dust by C/Fe mass ratio, after iron ore and coal dust are mixed, load in Rotary tube furnace and be 60min from the heating-up time that normal temperature is elevated to 950 DEG C, then 920 DEG C are cooled to, and at 920 DEG C of reducing roasting 35min; Reducing roasting ore deposit is 50% through ball milling 20min, ore milling concentration, and magneticstrength is 1.4KA/m magnetic separation; The rate of recovery obtaining result magnetic separation of iron ore concentrate is 75.75%, and concentrate grade is 50.05%.
Comparative example 4
Granularity is be less than after 1mm low-grade iron ore adds the NaCl of iron ore total mass 3% to press the agglomerate rolling into a ball into 10mm, 350g is taken after drying, then so C/Fe mass ratio is 0.4 join and get coal dust, by coal dust with to load in Rotary tube furnace with the iron ore group of NaCl and be elevated to 950 DEG C from normal temperature, the heating-up time of heating up is 60min, carries out coal-based direct reduction roasting 35min after being warming up to 950 DEG C; Reducing roasting ore deposit is 50% through ball milling 20min, ore milling concentration, and magneticstrength is 1.4KA/m magnetic separation; The rate of recovery obtaining result magnetic separation of iron ore concentrate is 59.78%, and concentrate grade is 63.35%.
Comparative example 5
The mass percent that low-grade iron ore and coal are less than 0.074mm after broken ore grinding process is respectively 80.45% and 47.38%, be 0.3 join and get coal by C/Fe mass ratio, join by 3.0% of iron ore butt total mass and get NaCl, join by 1.5% of iron ore butt total mass and get wilkinite, then, after powdered iron ore, coal, NaCl, wilkinite being mixed, disk pelletizing becomes diameter to be the bead of 3 ~ 8mm; After the drying of granulation bead, being loaded by the granulation bead of drying in Rotary tube furnace and to be elevated to 950 DEG C from normal temperature, the time of intensification is 60min, carries out coal-based direct reduction roasting 35min after being warming up to 950 DEG C; Reducing roasting ore deposit is 50% through ball milling 20min, ore milling concentration, and magneticstrength is 1.7KA/m magnetic separation; The rate of recovery obtaining result magnetic separation of iron ore concentrate is 68.89%, and concentrate grade is 71.84%.
Comparative example 6
The mass percent that low-grade iron ore and coal are less than 0.074mm after broken ore grinding process is respectively 80.45% and 47.38%, be 0.3 join and get coal by C/Fe mass ratio, join by 3.0% of iron ore butt total mass and get NaCl, join by 1.5% of iron ore butt total mass and get wilkinite, then, after powdered iron ore, coal, NaCl, wilkinite being mixed, disk pelletizing becomes diameter to be the bead (mass content of water is 11.62%) of 3 ~ 8mm; After granulation bead wet bulb enters kiln, the heating-up time that charge-temperature is elevated to 950 DEG C from normal temperature in Rotary tube furnace is 60min, carries out coal-based direct reduction roasting 35min at 950 DEG C, and the Pulverization ratio that reduction bead is less than 1mm is 28.58%; Reducing little ball warp ball milling 20min, ore milling concentration is 50%, and magneticstrength is 1.7KA/m magnetic separation; The rate of recovery obtaining result magnetic separation of iron ore concentrate is 65.89%, and concentrate grade is 68.83%.
Embodiment 1:
The mass percent that low-grade iron ore and coal are less than 0.074mm after broken ore grinding process is respectively 80.45% and 47.38%, is 0.3 join and get coal grain by C/Fe mass ratio; Join by 3.0% of iron ore butt total mass and get NaCl, join by 1.5% of iron ore butt total mass and get wilkinite, join water intaking by 6.0% of iron ore butt total mass; Then will join get coal grain, NaCl, wilkinite, water mixes and additive fully wetting to pulverized coal particle and penetrates in coal particle hole and crack under water function, obtains pretreated interior coal blending; Then interior coal blending is mixed with iron ores particle, disk pelletizing becomes diameter to be the granulation bead (wherein the mass percentage of water is 11.50%) of 3 ~ 8mm; After granulation bead wet bulb enters kiln, the heating-up time that charge-temperature is elevated to 950 DEG C from normal temperature in Rotary tube furnace is 60min, carries out coal-based direct reduction roasting 35min at 950 DEG C, reduction bead degree of metalization be 81.10% and the Pulverization ratio that is less than 1mm be 4.56%; Reducing little ball warp ball milling 20min, ore milling concentration is 50%, and magneticstrength is 1.7KA/m magnetic separation; The rate of recovery obtaining result magnetic separation of iron ore concentrate is 71.55%, and concentrate grade is 83.90%.
Embodiment 2:
The mass percent that low-grade iron ore and coal are less than 0.074mm after broken ore grinding process is respectively 80.45% and 47.38%, is 0.2 join and get coal grain by C/Fe mass ratio; Join by 3.0% of iron ore butt total mass and get NaCl, join by 1.5% of iron ore butt total mass and get wilkinite, join water intaking by 6.0% of iron ore butt total mass; Then will join get coal grain, NaCl, wilkinite, water mixes and additive fully wetting to pulverized coal particle and penetrates in coal particle hole and crack under water function, obtains pretreated interior coal blending; Then interior coal blending is mixed with iron ores particle, disk pelletizing becomes diameter to be the granulation bead (wherein the mass percentage of water is 11.58%) of 3 ~ 8mm; After granulation bead wet bulb enters kiln, the heating-up time that charge-temperature is elevated to 950 DEG C from normal temperature in Rotary tube furnace is 60min, carries out coal-based direct reduction roasting 35min at 950 DEG C, reduction bead degree of metalization be 73.61% and the Pulverization ratio that is less than 1mm be 3.92%; Reducing little ball warp ball milling 20min, ore milling concentration is 50%, and magneticstrength is 1.7KA/m magnetic separation; The rate of recovery obtaining result magnetic separation of iron ore concentrate is 73.88%, and concentrate grade is 80.19%.
Embodiment 3:
The mass percent that low-grade iron ore and coal are less than 0.074mm after broken ore grinding process is respectively 80.45% and 47.38%, is 0.4 join and get coal grain by C/Fe mass ratio; Join by 3.0% of iron ore butt total mass and get NaCl, join by 1.5% of iron ore butt total mass and get wilkinite, join water intaking by 6.0% of iron ore butt total mass; Then will join get coal grain, NaCl, wilkinite, water mixes and additive fully wetting to pulverized coal particle and penetrates in coal particle hole and crack under water function, obtains pretreated interior coal blending; Then interior coal blending is mixed with iron ores particle, disk pelletizing becomes diameter to be the granulation bead (wherein the mass percentage of water is 11.48%) of 3 ~ 8mm; After granulation bead wet bulb enters kiln, the heating-up time that charge-temperature is elevated to 950 DEG C from normal temperature in Rotary tube furnace is 60min, carries out coal-based direct reduction roasting 35min at 950 DEG C, reduction bead degree of metalization be 82.01% and the Pulverization ratio that is less than 1mm be 4.95%; Reducing little ball warp ball milling 20min, ore milling concentration is 50%, and magneticstrength is 1.7KA/m magnetic separation; The rate of recovery obtaining result magnetic separation of iron ore concentrate is 70.18%, and concentrate grade is 83.79%.
Embodiment 4:
The mass percent that low-grade iron ore and coal are less than 0.074mm after broken ore grinding process is respectively 80.45% and 47.38%, is 0.3 join and get coal grain by C/Fe mass ratio; Join by 2.0% of iron ore butt total mass and get NaCl, join by 1.5% of iron ore butt total mass and get wilkinite, join water intaking by 6.0% of iron ore butt total mass; Then will join get coal grain, NaCl, wilkinite, water mixes and additive fully wetting to pulverized coal particle and penetrates in coal particle hole and crack under water function, obtains pretreated interior coal blending; Then interior coal blending is mixed with iron ores particle, disk pelletizing becomes diameter to be the granulation bead (wherein the mass percentage of water is 11.69%) of 3 ~ 8mm; After granulation bead wet bulb enters kiln, the heating-up time that charge-temperature is elevated to 950 DEG C from normal temperature in Rotary tube furnace is 60min, carries out coal-based direct reduction roasting 35min at 950 DEG C, reduction bead degree of metalization be 65.18% and the Pulverization ratio that is less than 1mm be 7.58%; Reducing little ball warp ball milling 20min, ore milling concentration is 50%, and magneticstrength is 1.7KA/m magnetic separation; The rate of recovery obtaining result magnetic separation of iron ore concentrate is 67.59%, and concentrate grade is 70.95%.
Embodiment 5:
The mass percent that low-grade iron ore and coal are less than 0.074mm after broken ore grinding process is respectively 80.45% and 47.38%, is 0.3 join and get coal grain by C/Fe mass ratio; Join by 5.0% of iron ore butt total mass and get NaCl, join by 1.5% of iron ore butt total mass and get wilkinite, join water intaking by 6.0% of iron ore butt total mass; Then will join get coal grain, NaCl, wilkinite, water mixes and additive fully wetting to pulverized coal particle and penetrates in coal particle hole and crack under water function, obtains pretreated interior coal blending; Then interior coal blending is mixed with iron ores particle, disk pelletizing becomes diameter to be the granulation bead (wherein the mass percentage of water is 11.23%) of 3 ~ 8mm; After granulation bead wet bulb enters kiln, the heating-up time that charge-temperature is elevated to 950 DEG C from normal temperature in Rotary tube furnace is 60min, carries out coal-based direct reduction roasting 35min at 950 DEG C, reduction bead degree of metalization be 83.18% and the Pulverization ratio that is less than 1mm be 4.59%; Reducing little ball warp ball milling 20min, ore milling concentration is 50%, and magneticstrength is 1.7KA/m magnetic separation; The rate of recovery obtaining result magnetic separation of iron ore concentrate is 70.59%, and concentrate grade is 84.98%.
Embodiment 6:
The mass percent that low-grade iron ore and coal are less than 0.074mm after broken ore grinding process is respectively 80.45% and 47.38%, is 0.3 join and get coal grain by C/Fe mass ratio; Join by 3.0% of iron ore butt total mass and get NaCl, join by 0.5% of iron ore butt total mass and get wilkinite, join water intaking by 6.0% of iron ore butt total mass; Then will join get coal grain, NaCl, wilkinite, water mixes and additive fully wetting to pulverized coal particle and penetrates in coal particle hole and crack under water function, obtains pretreated interior coal blending; Then interior coal blending is mixed with iron ores particle, disk pelletizing becomes diameter to be the granulation bead (wherein the mass percentage of water is 11.98%) of 3 ~ 8mm; After granulation bead wet bulb enters kiln, the heating-up time that charge-temperature is elevated to 950 DEG C from normal temperature in Rotary tube furnace is 60min, carries out coal-based direct reduction roasting 35min at 950 DEG C, reduction bead degree of metalization be 80.28% and the Pulverization ratio that is less than 1mm be 7.95%; Reducing little ball warp ball milling 20min, ore milling concentration is 50%, and magneticstrength is 1.7KA/m magnetic separation; The rate of recovery obtaining result magnetic separation of iron ore concentrate is 73.61%, and concentrate grade is 80.28%.
Embodiment 7:
The mass percent that low-grade iron ore and coal are less than 0.074mm after broken ore grinding process is respectively 80.45% and 47.38%, is 0.3 join and get coal grain by C/Fe mass ratio; Join by 3.0% of iron ore butt total mass and get NaCl, join by 2.0% of iron ore butt total mass and get wilkinite, join water intaking by 6.0% of iron ore butt total mass; Then will join get coal grain, NaCl, wilkinite, water mixes and additive fully wetting to pulverized coal particle and penetrates in coal particle hole and crack under water function, obtains pretreated interior coal blending; Then interior coal blending is mixed with iron ores particle, disk pelletizing becomes diameter to be the granulation bead (wherein the mass percentage of water is 11.88%) of 3 ~ 8mm; After granulation bead wet bulb enters kiln, the heating-up time that charge-temperature is elevated to 950 DEG C from normal temperature in Rotary tube furnace is 60min, carries out coal-based direct reduction roasting 35min at 950 DEG C, reduction bead degree of metalization be 80.08% and the Pulverization ratio that is less than 1mm be 3.68%; Reducing little ball warp ball milling 20min, ore milling concentration is 50%, and magneticstrength is 1.7KA/m magnetic separation; The rate of recovery obtaining result magnetic separation of iron ore concentrate is 73.69%, and concentrate grade is 80.38%.
Embodiment 8:
The mass percent that low-grade iron ore and coal are less than 0.074mm after broken ore grinding process is respectively 80.45% and 47.38%, is 0.3 join and get coal grain by C/Fe mass ratio; Join by 3.0% of iron ore butt total mass and get NaCl, join by 1.5% of iron ore butt total mass and get wilkinite, join water intaking by 6.0% of iron ore butt total mass; Then will join get coal grain, NaCl, wilkinite, water mixes and additive fully wetting to pulverized coal particle and penetrates in coal particle hole and crack under water function, obtains pretreated interior coal blending; Then interior coal blending is mixed with iron ores particle, disk pelletizing becomes diameter to be the granulation bead (wherein the mass percentage of water is 11.78%) of 3 ~ 8mm; After granulation bead wet bulb enters kiln, the heating-up time that charge-temperature is elevated to 950 DEG C from normal temperature in Rotary tube furnace is 90min, carries out coal-based direct reduction roasting 35min at 950 DEG C, reduction bead degree of metalization be 81.08% and the Pulverization ratio that is less than 1mm be 4.86%; Reducing little ball warp ball milling 20min, ore milling concentration is 50%, and magneticstrength is 1.7KA/m magnetic separation; The rate of recovery obtaining result magnetic separation of iron ore concentrate is 72.65%, and concentrate grade is 81.35%.
Embodiment 9:
The mass percent that low-grade iron ore and coal are less than 0.074mm after broken ore grinding process is respectively 80.45% and 47.38%, is 0.3 join and get coal grain by C/Fe mass ratio; Join by 3.0% of iron ore butt total mass and get NaCl, join by 1.5% of iron ore butt total mass and get wilkinite, join water intaking by 6.0% of iron ore butt total mass; Then will join get coal grain, NaCl, wilkinite, water mixes and additive fully wetting to pulverized coal particle and penetrates in coal particle hole and crack under water function, obtains pretreated interior coal blending; Then interior coal blending is mixed with iron ores particle, disk pelletizing becomes diameter to be the granulation bead (wherein the mass percentage of water is 11.33%) of 3 ~ 8mm; After granulation bead wet bulb enters kiln, the heating-up time that charge-temperature is elevated to 950 DEG C from normal temperature in Rotary tube furnace is 60min, carries out coal-based direct reduction roasting 45min at 950 DEG C, reduction bead degree of metalization be 82.05% and the Pulverization ratio that is less than 1mm be 5.87%; Reducing little ball warp ball milling 20min, ore milling concentration is 50%, and magneticstrength is 1.7KA/m magnetic separation; The rate of recovery obtaining result magnetic separation of iron ore concentrate is 70.53%, and concentrate grade is 83.35%.
Embodiment 10:
The mass percent that low-grade iron ore and coal are less than 0.074mm after broken ore grinding process is respectively 80.45% and 47.38%, is 0.3 join and get coal grain by C/Fe mass ratio; Join by 3.0% of iron ore butt total mass and get NaCl, join by 1.5% of iron ore butt total mass and get wilkinite, join water intaking by 6.0% of iron ore butt total mass; Then will join get coal grain, NaCl, wilkinite, water mixes and additive fully wetting to pulverized coal particle and penetrates in coal particle hole and crack under water function, obtains pretreated interior coal blending; Then interior coal blending is mixed with iron ores particle, disk pelletizing becomes diameter to be the granulation bead (wherein the mass percentage of water is 11.65%) of 3 ~ 8mm; After granulation bead wet bulb enters kiln, the heating-up time that charge-temperature is elevated to 920 DEG C from normal temperature in Rotary tube furnace is 60min, carries out coal-based direct reduction roasting 35min at 920 DEG C, reduction bead degree of metalization be 76.25% and the Pulverization ratio that is less than 1mm be 4.78%; Reducing little ball warp ball milling 20min, ore milling concentration is 50%, and magneticstrength is 1.7KA/m magnetic separation; The rate of recovery obtaining result magnetic separation of iron ore concentrate is 73.58%, and concentrate grade is 74.33%.
Embodiment 11:
The mass percent that low-grade iron ore and coal are less than 0.074mm after broken ore grinding process is respectively 80.45% and 47.38%, is 0.3 join and get coal grain by C/Fe mass ratio; Join by 3.0% of iron ore butt total mass and get NaCl, join by 1.5% of iron ore butt total mass and get wilkinite, join water intaking by 6.0% of iron ore butt total mass; Then will join get coal grain, NaCl, wilkinite, water mixes and additive fully wetting to pulverized coal particle and penetrates in coal particle hole and crack under water function, obtains pretreated interior coal blending; Then interior coal blending is mixed with iron ores particle, disk pelletizing becomes diameter to be the granulation bead (wherein the mass percentage of water is 11.57%) of 3 ~ 8mm; After granulation bead wet bulb enters kiln, the heating-up time that charge-temperature is elevated to 980 DEG C from normal temperature in Rotary tube furnace is 60min, carries out coal-based direct reduction roasting 35min at 980 DEG C, reduction bead degree of metalization be 82.28% and the Pulverization ratio that is less than 1mm be 4.58%; Reducing little ball warp ball milling 20min, ore milling concentration is 50%, and magneticstrength is 1.7KA/m magnetic separation; The rate of recovery obtaining result magnetic separation of iron ore concentrate is 74.48%, and concentrate grade is 83.38%.

Claims (10)

1. the method for a low-grade iron ore direct-reduction; It is characterized in that, comprise the following steps:
Step one
Using pending low-grade iron ore butt quality for benchmark gets coal dust, additive, binding agent and water as interior coal blending pretreating raw material with joining;
Wherein,
Coal dust is 0.2 ~ 0.4 join and get by C/Fe mass ratio; In described coal grain, the butt quality that granularity is less than the coal dust of 0.074mm accounts for more than 45% of coal dust butt total mass;
Additive is joined by 2.0% ~ 5.0% of low-grade iron ore butt quality and is got, and described additive is selected from NaCl, CaCl 2, FeCl 3, Na 2cO 3in at least one;
Binding agent is joined by 0.5% ~ 2.0% of low-grade iron ore butt quality and is got, and described binding agent is selected from least one in wilkinite, composite bentonite;
Water is joined by 6.0% ~ 7.0% of low-grade iron ore butt quality and is got;
Step 2
Step one is joined coal blending pretreating raw material in getting to carry out being mixed to the fully wetting and additive of pulverized coal particle and penetrate in coal particle hole and crack under water function, obtain pretreated interior coal blending;
Step 3
After pretreated for step 2 gained interior coal blending is mixed with pending low-grade iron ore, adopt disk or drum polletizing, obtain the granulation bead that diameter is 3 ~ 8mm; In described granulation bead, the mass percentage of water is 8% ~ 12%; In described pending low-grade iron ore particle, the butt quality that granularity is less than 0.074mm particle accounts for more than 70% of pending low-grade iron ore butt total mass;
Step 4
Directly sent in rotary kiln by step 3 gained granulation bead, drying, preheating, coal-based direct reduction calcination process, obtain reducing material, and reducing material obtains reducing roasting bead and carbon residue through dry magnetic separation after cooling under the condition of isolated air; The temperature of described coal-based direct reduction is 920 DEG C ~ 980 DEG C;
Step 5
After little for the reducing roasting of step 4 gained ball warp ore grinding, magnetic separation process, obtain iron ore concentrate;
Or
Little for the reducing roasting of step 4 gained ball warp ore grinding, magnetic separation process, regrinding and reconcentration are obtained reduced iron powder.
2. the method for a kind of low-grade iron ore direct-reduction according to claim 1; It is characterized in that: in step one, the fugitive constituent of described coal dust is more than or equal to 25%; Fixed carbon content is more than or equal to 45%.
3. the method for a kind of low-grade iron ore direct-reduction according to claim 2; It is characterized in that: in step one, described coal dust is selected from least one in brown coal, hard coal, biomass carbon.
4. the method for a kind of low-grade iron ore direct-reduction according to claim 1; It is characterized in that: in described pending low-grade iron ore, the mass percentage of iron is more than or equal to 28%.
5. the method for a kind of low-grade iron ore direct-reduction according to claim 1; It is characterized in that: in step 3, described granulation bead is at logical N 2in the retort furnace of protection after 800 DEG C of dryings, obtain dried granulation bead; Get dried granulation bead 0.5Kg, make it be that 0.5m falls from height, after repeating 3 times, the quality that granularity is less than or equal to the powder of 1.0mm is less than or equal to 25g.
6. the method for a kind of low-grade iron ore direct-reduction according to claim 1; It is characterized in that: in step 4, the time of coal-based direct reduction calcination process is 20min ~ 45min.
7. the method for a kind of low-grade iron ore direct-reduction according to claim 1; It is characterized in that, described step 4 is:
Sent in rotary kiln by step 3 gained granulation bead, under 500 DEG C ~ 920 DEG C high-temperature gas effects of rotary kiln afterbody, carry out drying, intensification and preheating, temperature is elevated to 920 DEG C from normal temperature, and the time is 60min ~ 90min; Again at 920 DEG C ~ 980 DEG C, carry out coal-based direct reduction roasting 20min ~ 45min and make reducing material; Reducing material completely cuts off air cooling to 90 DEG C ~ 110 DEG C by the cooling drum of outside water spray, adopts dry magnetic separation to be separated and obtain reducing roasting bead and carbon residue after cooling.
8. the method for a kind of low-grade iron ore direct-reduction according to claim 1; It is characterized in that: in step 4, gained carbon residue can be used as coal dust raw material in step one.
9. the method for a kind of low-grade iron ore direct-reduction according to claim 1; It is characterized in that: in step 4, the degree of metalization of gained reducing roasting bead is 60% ~ 85%.
10. the method for a kind of low-grade iron ore direct-reduction according to claim 1; It is characterized in that, step 5 is: after butt mass percentage step 4 gained reducing roasting bead ore grinding to granularity being less than or equal to 0.074mm particle equals to be greater than 95% of reducing roasting bead total mass, adopt magnetic separation, during magnetic separation, magneticstrength is 1.4 ~ 2.0KA/m.
CN201510122728.6A 2015-03-19 2015-03-19 Low-grade iron ore direct reduction method Pending CN104862440A (en)

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CN105772706A (en) * 2016-04-19 2016-07-20 玉溪大红山矿业有限公司 Method for preparing qualified microalloy iron powder through high-carbon and high-hydrogen loss one-time-reduction iron powder
CN105880584A (en) * 2016-04-19 2016-08-24 玉溪大红山矿业有限公司 Method for preparing qualified microalloy iron powder through high-hydrogen-loss high-carbon primary reduced iron powder
CN106282467A (en) * 2016-10-30 2017-01-04 徐州贝克福尔节能环保技术有限公司 A kind of iron mine fine coal base produces direct-reduction facilities and method
CN106591572A (en) * 2017-01-06 2017-04-26 中南大学 Method for reinforcing preparation and reduction of carbon-containing pellets in iron ore
CN107177732A (en) * 2017-05-19 2017-09-19 安徽工业大学 It is a kind of to prepare high strength bainite agglomerate and gas iron co-production as bonding carrier with biomass
CN108676951A (en) * 2018-06-15 2018-10-19 甘肃酒钢集团宏兴钢铁股份有限公司 A kind of hydrocarbon joint direct-reduction technique of iron ore concentrate
CN108690909A (en) * 2017-04-05 2018-10-23 祁东县顺达矿业有限公司 The method that kiln is tied in preventing rotary kiln from producing
CN111334633A (en) * 2020-04-29 2020-06-26 王安新 External heating type vertical rotary kiln
CN112588201A (en) * 2020-12-30 2021-04-02 重庆长江造型材料(集团)股份有限公司 Consolidation granulation method of slurry
CN113684337A (en) * 2021-07-29 2021-11-23 张雷 Method and device for optimizing iron ore by gas coal double-base direct reduction and magnetic separation

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CN102168159A (en) * 2011-04-15 2011-08-31 北京科技大学 Reducing agent for carrying out direct reduction roasting on limonite and hematite to produce reduced iron
CN103993166A (en) * 2014-05-13 2014-08-20 中南大学 Method for improving grade of low-grade iron ore

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CN105880584A (en) * 2016-04-19 2016-08-24 玉溪大红山矿业有限公司 Method for preparing qualified microalloy iron powder through high-hydrogen-loss high-carbon primary reduced iron powder
CN105772706A (en) * 2016-04-19 2016-07-20 玉溪大红山矿业有限公司 Method for preparing qualified microalloy iron powder through high-carbon and high-hydrogen loss one-time-reduction iron powder
CN105880584B (en) * 2016-04-19 2018-08-17 玉溪大红山矿业有限公司 The method for producing qualified micro alloy iron powder with a reduced iron powder of high hydrogen loss high-carbon
CN105772706B (en) * 2016-04-19 2018-01-16 玉溪大红山矿业有限公司 The method that qualified micro alloy iron powder is produced with a reduced iron powder of the high hydrogen loss of high-carbon
CN106282467B (en) * 2016-10-30 2018-02-06 徐州贝克福尔节能环保技术有限公司 A kind of iron ore fine coal base production direct-reduction facilities and method
CN106282467A (en) * 2016-10-30 2017-01-04 徐州贝克福尔节能环保技术有限公司 A kind of iron mine fine coal base produces direct-reduction facilities and method
CN106591572A (en) * 2017-01-06 2017-04-26 中南大学 Method for reinforcing preparation and reduction of carbon-containing pellets in iron ore
CN108690909A (en) * 2017-04-05 2018-10-23 祁东县顺达矿业有限公司 The method that kiln is tied in preventing rotary kiln from producing
CN107177732A (en) * 2017-05-19 2017-09-19 安徽工业大学 It is a kind of to prepare high strength bainite agglomerate and gas iron co-production as bonding carrier with biomass
CN107177732B (en) * 2017-05-19 2019-05-17 安徽工业大学 It is a kind of that biomass is used to prepare high strength bainite agglomerate and gas iron co-production as bonding carrier
CN108676951A (en) * 2018-06-15 2018-10-19 甘肃酒钢集团宏兴钢铁股份有限公司 A kind of hydrocarbon joint direct-reduction technique of iron ore concentrate
CN111334633A (en) * 2020-04-29 2020-06-26 王安新 External heating type vertical rotary kiln
CN112588201A (en) * 2020-12-30 2021-04-02 重庆长江造型材料(集团)股份有限公司 Consolidation granulation method of slurry
CN113684337A (en) * 2021-07-29 2021-11-23 张雷 Method and device for optimizing iron ore by gas coal double-base direct reduction and magnetic separation

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