CN101575670B - Pellet ore pre-heating method, preparation method and device therefor - Google Patents
Pellet ore pre-heating method, preparation method and device therefor Download PDFInfo
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- CN101575670B CN101575670B CN2009101480679A CN200910148067A CN101575670B CN 101575670 B CN101575670 B CN 101575670B CN 2009101480679 A CN2009101480679 A CN 2009101480679A CN 200910148067 A CN200910148067 A CN 200910148067A CN 101575670 B CN101575670 B CN 101575670B
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Abstract
The invention provides a pellet ore pre-heating method, comprising the following steps: green pellets are sent into a drying grate to sequentially carry out primary drying, secondary drying, primary pre-heating and secondary pre-heating; the fume discharged by a rotary kiln is used as a hot air source when the secondary pre-heating is carried out; the fume discharged by the secondary cooling of a cooler is used as the hot air source when the primary pre-heating is carried out; the fume discharged by the secondary pre-heating is used as the hot air source when the secondary drying is carried out; and the fume discharged by the tertiary cooling of the cooler is used as the hot air source when the primary drying is carried out, and the fume discharged by the tertiary cooling is heated to the preset temperature when the primary drying is carried out. Compared with the prior art, in the invention, after the fume discharged by the tertiary cooling is heated to the preset temperature when theprimary drying is carried out, the fume is recycled to be used for the primary drying, thus not only avoiding the energy loss, but also providing sufficient air amount for the primary drying. In addi tion, a diffusing chimney for discharging the fume into the air is unnecessary, thus avoiding environment pollution.
Description
Technical field
The present invention relates to metallurgical raw material, be specifically related to a kind of pellet ore pre-heating method, preparation method and device.
Background technology
Pellet is one of main raw material of blast furnace ironmaking and dri.Compare with agglomerate, pellet has multiple advantage.For example, the physical strength of pellet when cold conditions is higher than agglomerate, therefore when transportation, loading and unloading and storage, is difficult for broken and cracking, consumes and lacks, and the powder of generation is few, helps improving the ventilation property of blast furnace stock column, makes the gas stream in the stove uniform distribution.And, because pellet grade is high and bulk density is big, therefore help increasing the effective weight of blast furnace stock column, improve output and reduce coke ratio.In addition, the process energy consumption of pellet is starkly lower than agglomerate, and the Dust Capacity that pellet is supervened in process of production obviously is less than agglomerate, has reduced the pollution to environment relatively.Based on multiple advantage more than the pellet, obtain wider popularization in order to make pellet, people have been developed the multiple method for preparing pellet.
In the prior art, the method for preparing pellet mainly contains three kinds, is respectively: shaft furnace is produced the pelletizing method, and belt type roasting machine prepares the pelletizing method, the grate kiln legal system is equipped with the pelletizing method.Compare with other two kinds of methods, the grate kiln method has that good product quality, unit throughput are big, rotary kiln can be used the coal heat supply, is applicable to the multiple advantage of scale operation, has obtained using widely.
See also Fig. 1, be employing grate kiln prepared pellet schematic representation of apparatus of the prior art.As shown in Figure 1, said device comprises the chain-grate machine 11 of preheating green pellets, the rotary kiln 12 that the pelletizing after the chain-grate machine preheating is passed through in roasting, the cooler 13 that the pelletizing of rotary kiln baking is passed through in cooling.Said chain-grate machine 11 is divided into the first dryer section DD1, the second dryer section DD2, transition preheating section TPH, preheating section PH successively from infeed end one side; Said central cooler is divided into the first cooling section C1, the second cooling section C2, the 3rd cooling section C3 successively from infeed end.
The exhaust side of the second cooling section C2 comprises the first air supply duct 13a that is communicated with the transition preheating section, and through this first air supply duct 13a, the flue gas that the second cooling section C2 discharges is recovered utilization pelletizing is carried out the transition preheating.The exhaust side of the 3rd cooling section C3 comprises the 4th air supply duct 103c that is communicated with the first dryer section DD1 and diffuses chimney 103b; Through said the 4th air supply duct 103c; The part of smoke that the 3rd cooling section C3 discharges is sent to the first dryer section DD1 pelletizing is carried out drying, diffuses the exhaust air rate of chimney 103b through adjustment air quantity and the wind-warm syndrome of the 4th air supply duct 103c are regulated.The exhaust side of preheating section PH comprises the second air supply duct 11a that is communicated with the second dryer section DD2, and through this second air supply duct, the flue gas of discharging from preheating section is recovered to the second dryer section DD2 pelletizing is carried out second stage drying.
In device shown in Figure 1, the flue gas of being discharged by the 3rd cooling section C3 is discharged a part of low-temperature flue gas by diffusing chimney as the hot air source of first dryer section, adjusts the temperature and the air quantity of first dryer section through adjusting said free air delivery of diffusing chimney.Above-mentioned prior art problems is; Because part of smoke is diffused chimney and is drained; Though can reach the needed temperature of first dryer section, air quantity can not be satisfied the demand, and also caused the loss of system capacity from diffusing flue gas that chimney drains.
Consider in the prior art to exist as above-mentioned shortcoming, therefore, need a kind of pellet ore pre-heating method that can avoid system energy loss, sufficient air quantity is provided for the pelletizing drying.
Summary of the invention
The technical problem that the present invention solves is, provides a kind of and can avoid power loss, and pellet ore pre-heating method, preparation method and the device of sufficient air quantity are provided for the pelletizing drying.
In order to solve the problems of the technologies described above, the present invention provides a kind of pellet ore pre-heating method, comprising: green pellets is sent into chain-grate machine carry out first step drying, second stage drying, first step preheating, second stage preheating successively;
The flue gas of being discharged by rotary kiln when carrying out the preheating of the said second stage is as hot air source, and said rotary kiln is used for the preheating pelletizing of roasting after the chain-grate machine preheating;
The flue gas of being discharged by the second stage cooling of cooler when carrying out said first step preheating is as hot air source; Said cooler is used to cool off the roasting pelletizing behind rotary kiln baking, and said cooler carries out first step cooling, second stage cooling, third stage cooling successively to the roasting pelletizing;
Carry out the said second stage when dry by the flue gas of discharging after the preheating of the second stage as hot air source;
Carry out flue gas that the said first step discharged by the third stage cooling of cooler when dry as hot air source, the flue gas that said third stage cooling is discharged is heated to the design temperature T of first step when dry
DD1
Preferably, the flue gas of said third stage cooling discharge heats through hotblast stove.
Preferably, the said design temperature T of first step when dry that carry out
DD1Be lower than the burst temperature T of green pellets
Explosion
Preferably, the said design temperature T of first step when dry that carry out
DD1Satisfy following condition: T
Explosion-250 ℃≤T
DD1≤T
Explosion-100 ℃.
Design temperature T when preferably, carrying out said second stage drying
DD2Satisfy following condition: T
Explosion-100 ℃≤T
DD2≤T
Explosion-20 ℃.
Preferably, the iron-bearing material for preparing said green pellets comprises the rhombohedral iron ore of 70wt% at least.
Preferably, said iron-bearing material comprises and also comprises in sulfate slag, magnetite, spathic iron ore, limonite, the pyrite one or more.
Preferably, said first step drying is that exhausting is dry.
The present invention also provides a kind of preparation method of pellet, comprises step:
A) green pellets is sent into chain-grate machine and carry out first step drying, second stage drying, first step preheating, second stage preheating successively;
B) the preheating pelletizing after the preheating of the second stage is sent into rotary kiln baking;
C) the roasting pelletizing after the roasting is sent into cooler successively and carry out first step cooling, second stage cooling, third stage cooling;
The flue gas that said first step cooling is discharged is admitted to the rotary kiln baking pelletizing; The flue gas of discharging from rotary kiln carries out second stage preheating; The flue gas that second stage preheating is discharged carries out second stage drying; The flue gas that second stage cooling is discharged is used to carry out first step preheating, the design temperature T the when flue gas that third stage cooling is discharged is heated to first step drying
DD1After be used to carry out first step drying.
Preferably, the additive for preparing said green pellets comprises: one or more in Wingdale, slaked lime, rhombspar, the forsterite.
Preferably, prepare said green pellets raw material and join charcoal in also comprising, join charcoal in said to comprise: one or more in hard coal, coke, refinery coke, the charcoal.
Preferably, the flue gas of said third stage cooling discharge is through the hotblast stove heating.
Preferably, the said design temperature T of first step when dry that carry out
DD1Be lower than the burst temperature T of green pellets
Explosion
Preferably, the said design temperature T of second stage when dry that carry out
DD2Satisfy following condition: T
Explosion-100 ℃≤T
DD2≤T
Explosion-20 ℃.
The present invention also provides a kind of device for preparing pellet, comprising: the cooler of the rotary kiln of the chain-grate machine of preheating green pellets, the pelletizing of roasting after the chain-grate machine preheating, the pelletizing of cooling behind rotary kiln baking;
Said chain-grate machine is divided into first dryer section, second dryer section, first preheating section, second preheating section successively from infeed end one side;
Said cooler is divided into first cooling section, second cooling section, the 3rd cooling section successively from infeed end;
The exhaust side of said second cooling section comprises first air supply duct that is communicated with first preheating section; The exhaust side of said second preheating section comprises second air supply duct that is communicated with second dryer section; The exhaust side of said the 3rd cooling section comprises the 3rd air supply duct that is communicated with first dryer section, and said the 3rd air supply duct is provided with heating unit.
Preferably, said heating unit is a hotblast stove.
The present invention provides a kind of pellet ore pre-heating method, and behind flue gas heating to the first step exsiccant design temperature of the present invention with the third stage cooling discharge of cooler, all recovery is used for first step drying.Compared with prior art, cool off the flue gas of discharge owing to the third stage and all recycle, therefore avoided the loss of energy, and after the whole recovery of flue gas with third stage cooling discharge, can competent air quantity be provided for first step drying.In addition, diffuse the flue gas that chimney discharges third stage cooling and enter in the atmosphere, also avoided the pollution that air is caused owing to abandon using.
Description of drawings
Fig. 1 is a preparation pellet schematic representation of apparatus of the prior art;
Fig. 2 is the synoptic diagram of a kind of embodiment of preparation pellet device provided by the invention.
Embodiment
See also Fig. 2, be the synoptic diagram of a kind of embodiment of the device of preparation pellet provided by the invention.
The device of preparation pellet provided by the invention comprises the chain-grate machine 11 of preheating green pellets, the rotary kiln 12 of roasting preheating pelletizing, the cooler 13 of cooling roasting pelletizing; In this embodiment; Cooler is a central cooler, and cooler also can adopt other refrigerating units well known to those skilled in the art.Chain-grate machine is divided into the first dryer section DD1, the second dryer section DD2, the first preheating section TPH, the second preheating section PH successively from infeed end one side.Central cooler 13 once is divided into the first cooling section C1, the second cooling section C2, the 3rd cooling section C3 successively from infeed end.
The flue gas of discharging from the first cooling section C1 is recovered to rotary kiln pelletizing is carried out roasting, and the flue gas of discharging from rotary kiln is admitted to second preheating section pelletizing is carried out second stage preheating.
The exhaust side of the second cooling section C2 comprises the first air supply duct 13a that is communicated with first preheating section, and through this first air supply duct, the flue gas of discharging from second colling end is recovered to first preheating section and carries out first step preheating.
Exhaust side at the second preheating section PH comprises the second air supply duct 11a that is communicated with the second dryer section DD2, and through this second air supply duct 11a, the flue gas of discharging from the second preheating section PH continues to be recovered utilization, is used to carry out second stage drying.
The exhaust side of the 3rd cooling section comprises the 3rd air supply duct 13c that is communicated with the first dryer section DD1, through said the 3rd air supply duct 13c, the exhaust of the 3rd cooling section all is back to the first dryer section DD1, is that the first dryer section DD1 provides competent air quantity.In addition; On the 3rd air supply duct; Be connected with the hotblast stove of hot blast 13b is provided in the 3rd pipeline, the air quantity through control hotblast stove 13b is heated to first step exsiccant design temperature with the hot blast of hotblast stove and the mixed flue-gas temperature of flue gas of the 3rd section discharge.
Said hotblast stove also can be compared with hotblast stove for heating units such as electric furnace, pipeline burners, adopts pipeline burner heating investment more to economize.Through said hotblast stove 13b; After the flue gas of the 3rd section discharge is heated to first step exsiccant design temperature; All recovery is used to carry out first step drying, and compared with prior art, device provided by the invention has all reclaimed the flue gas heat that cooler is discharged; Avoided the loss of energy, and can competent air quantity be provided for first step drying.In addition, diffuse chimney part of smoke is discharged in the atmosphere owing to abandon using, device provided by the invention can also avoid causing the pollution of environment.
In this embodiment; First step drying and second stage drying all adopt exhausting exsiccant form; Therefore the device of said preparation pelletizing also comprises a plurality of extractor fan (not shown) well known to those skilled in the art, is used for flue gas is extracted into the bed of material in each stage (first dryer section, second dryer section, first preheating section, second preheating section) of chain-grate machine.According to the present invention, first step drying also can adopt the form of forced air drying, can reach the object of the invention equally.In addition, the device of said preparation pelletizing also comprises the electric precipitation machine 14 and the air exhausting device 15 of recovery flue gas well known to those skilled in the art.The flue gas that whole device produces finally carries out dedusting by electric precipitation machine 14, is discharged by air exhausting device 15 after reaching emission standard.
Pellet ore pre-heating method provided by the invention and preparation method realize through said apparatus, below specify pellet ore pre-heating method provided by the invention and preparation method.
The embodiment of a kind of pellet ore pre-heating method provided by the invention comprises: green pellets is sent into chain-grate machine carry out first step drying, second stage drying, first step preheating, second stage preheating successively;
The flue gas of being discharged by rotary kiln when carrying out the preheating of the said second stage is as hot air source, and said rotary kiln is used for the preheating pelletizing of roasting after the chain-grate machine preheating;
The flue gas of being discharged by the second stage cooling of cooler when carrying out said first step preheating is as hot air source; Said cooler is used to cool off the roasting pelletizing behind rotary kiln baking, and said cooler carries out first step cooling, second stage cooling, third stage cooling successively to the roasting pelletizing;
Carry out the said second stage when dry by the flue gas of discharging after the preheating of the second stage as hot air source;
Carry out flue gas that the said first step discharged by the third stage cooling of cooler when dry as hot air source, the flue gas that said third stage cooling is discharged is heated to the design temperature of first step when dry.
The preparing method's of a kind of pellet provided by the invention embodiment comprises:
A) green pellets is sent into chain-grate machine and carry out first step drying, second stage drying, first step preheating, second stage preheating successively;
B) the preheating pelletizing after the preheating of the second stage is sent into rotary kiln baking;
C) the roasting pelletizing after the roasting is sent into cooler successively and carry out first step cooling, second stage cooling, the 3rd section cooling;
The flue gas that said first step cooling is discharged is admitted to the rotary kiln baking pelletizing; The flue gas of discharging from rotary kiln carries out second stage preheating; The flue gas that second stage preheating is discharged carries out second stage drying; The flue gas that second stage cooling is discharged is used to carry out first step preheating, is used to carry out first step drying behind the design temperature when third stage cooling discharge flue gas is heated to first step drying.
According to the present invention; Said green pellets is by iron-bearing material and tackiness agent; Mix certain water; Process through making ball, iron-bearing material preferably includes the rhombohedral iron ore of 70wt% at least, can also comprise in the pelletizing powder of selecting sulfate slag, magnetite, spathic iron ore, limonite, pyrite or recovery one or more.Preferably, rhombohedral iron ore shared proportion in iron-bearing material is no less than 70wt%, and is preferred, and rhombohedral iron ore shared proportion in iron-bearing material is no less than 85%, and is most preferred, and rhombohedral iron ore shared proportion in iron-bearing material is no less than 95%.
When said iron-bearing material is made ball, need mix tackiness agent, tackiness agent can be preferably wilkinite for wilkinite, Mierocrystalline cellulose.For the addition of tackiness agent, preferably account for iron-bearing material weight 0.5%~3%, preferred, the addition of tackiness agent accounts for 0.8%~2% of iron-bearing material weight.In addition, when iron-bearing material is made ball, also can blast blending, additive can be selected from one or more in Wingdale, slaked lime, rhombspar, the forsterite.Amount the present invention for additive does not have special restriction, and is preferred, and behind the adding additive, the basicity of green pellets is 0.8~1.5, and is preferred, and the addition of additive makes that the basicity of green pellets is 1.0~1.2.Basicity described herein refers to that dual alkalinity is CaO/SiO
2The value of (weight ratio).During green pellets, join carbon in can also adding in preparation, join carbon in said and comprise in hard coal, coke, refinery coke, the charcoal one or more.For the granulating equipment of making green pellets, can select equipment well known to those skilled in the art, like granulating disc, cylinder tablets press etc.
After iron-bearing material is made ball, obtain green pellets, the particle diameter of said green pellets is preferably 6mm~18mm, and is preferred, and the particle diameter of said green pellets is 9mm~16mm.Water-content in the green pellets is preferably 7wt%~12.5wt%; Preferred, the water-content of green pellets is 7.5wt%~10.5wt%; Preferred, the water-content of green pellets is 8.5wt%~9wt%.In addition, for the intensity of green pellets, its drop number preferably is no less than 3 times/0.5m, and preferred, the drop number of green-ball figure is 7 times/0.5m, and is preferred, and the drop number of green pellets is 9 times/0.5m.
According to the present invention, said first step exsiccant design temperature T
DD1Burst temperature T less than green-ball
Explosion, preferred, said first step exsiccant design temperature T
DD1Satisfy following condition: T
Explosion-250 ℃≤T
DD1≤T
Explosion-100 ℃; Preferred, said first step exsiccant design temperature T
DD1Satisfy following condition: T
Explosion-220 ℃≤T
DD1≤T
Explosion-120 ℃; Most preferred, said first step exsiccant design temperature T
DD1Satisfy following condition: T
Explosion-200 ℃≤T
DD1≤T
Explosion-150 ℃.
Said green pellets is carried out the first step when dry, after the flue gas of being discharged by central cooler third stage refrigerative is heated to the design temperature of first step dryer section DD1, as the hot air source of the first dryer section DD1.When carrying out first step drying,, be preferably 0.2m/s~2.5m/s for the charge level wind speed; Preferred, first step exsiccant charge level wind speed is 0.5m/s~2.0m/s; Most preferred, first step exsiccant charge level wind speed is 1.0m/s~1.6m/s.Carry out the first step when dry, be preferably 1.5min~5min time of drying, preferred, the first step is 2min~4min time of drying, and is preferred, and first step time of drying is 2min~3min.Behind the feeding speed that configures chain-grate machine, set the first step exsiccant time through the length of setting first dryer section.For the dry mode that is adopted of the first step, can adopt forced air drying method well known to those skilled in the art or exhausting drying means, this present invention is not had special restriction.Because the air blast operating environment is relatively poor, preferably adopts exhausting exsiccant method that pelletizing is carried out first step drying.
Be admitted to the second dryer section DD2 after the green pellets process first step drying and proceed second stage drying.In carrying out first step exsiccant process, the removal that is dried of the portion of water in the green pellets, second stage exsiccant design temperature T
DD2Be higher than first step exsiccant design temperature T
DD1, preferred, second stage exsiccant design temperature T
DD2Preferably be set to less than burst temperature T
Quick-fried SplitPreferably, said second stage exsiccant design temperature T
DD2Satisfy following condition: T
Explosion-100 ℃≤T
DD2≤T
Explosion-20 ℃; Preferred, said second stage exsiccant design temperature T
DD2Satisfy following condition: T
Explosion-80 ℃≤T
DD2≤T
Explosion2-40 ℃.
When said green pellets is carried out second stage drying, send into the second dryer section DD2 as hot air source by the flue gas of discharging after the preheating of the second stage.For the dry mode that is adopted in the second stage, can adopt exhausting drying means well known to those skilled in the art.When carrying out second stage drying, the charge level wind speed is preferably 0.2m/s~2.5m/s; Preferred, second stage exsiccant charge level wind speed is 0.5m/s~2.0m/s; Most preferred, second stage exsiccant charge level wind speed is 1.0m/s~1.4m/s.Carry out the second stage when dry, be preferably 1.5min~5min time of drying, preferred, the second stage is 2min~4min time of drying, and is preferred, and second stage time of drying is 2min~3min.Behind the feeding speed that configures chain-grate machine, set partial time of drying through the length of setting second dryer section.
After green pellets process first step drying and the second stage drying, need carry out first step preheating and second stage preheating.According to the present invention, the flue gas of being discharged by rotary kiln is as the hot air source of second stage preheating, and the flue gas of being discharged by second cooling section of cooler is as the hot air source of first step preheating.For the design temperature of second stage preheating and first step preheating, use those skilled in the art's common practise to set according to the processing requirement of pellet, this present invention is not had special restriction.
When carrying out second stage preheating, the charge level wind speed is preferably 0.5m/s~1.2m/s, and is preferred, and the charge level wind speed of second stage preheating is preferably 0.5m/s~0.9m/s.Be preferably 3min~10min the warm up time for second stage preheating, preferred, and second stage warm up time is 4min~8min.When carrying out first step preheating, behind the charge level wind speed of setting second stage drying and second stage preheating, the charge level wind speed of first step preheating is selected between the charge level wind speed of second stage drying and second stage preheating, and this present invention is not had special restriction.Be preferably 1.5min~5min the warm up time for first step preheating, preferred, and first step warm up time is 2min~4.5min.
According to the present invention; Said green pellets is defined as dry pelletizing through the pelletizing that obtains behind dry DD 1 of the first step and the dry DD2 in the second stage successively in this article; Said dry pelletizing is defined as the preheating pelletizing through the pelletizing that obtains after first step preheating, the second stage preheating more successively in this article in chain-grate machine; Said preheating pelletizing is admitted to the pelletizing that rotary kiln carries out obtaining after the roasting and is defined as the roasting pelletizing, and the pelletizing that obtains after the cooling of roasting pelletizing through hereinafter described central cooler is defined as finished pellet.
When adopting central cooler to cool off, the roasting pelletizing obtains finished pellet through first step cooling, second stage cooling, the third stage after cooling off successively in central cooler.In order the roasting pelletizing to be cooled to the temperature of finished pellet; Cooling area for the first cold-zone section, second cooling section and the 3rd cooling section in the central cooler; Can set according to those skilled in the art's common practise, this present invention is not had special restriction.
Green pellets burst temperature among this paper is tested according to the dynamic method of U.S. AC company: break 4% top temperature that can bear as burst temperature with green pellets.The ultimate compression strength of the finished pellet among this paper is measured on the compression strength of green pellet appearance according to the method among the international standard ISO4700.The following method of shatter strength of green pellet test among this paper: the green-ball that to get 30 granularities be 8mm~12mm; Be free to drop down on the thick steel plate of 5mm from 0.5m; Carry out repeatedly, in the time of till green-ball cracks, the drop number of each green-ball subtracts 1 and is dropping strength; Get the dropping strength of the MV of each shatter strength of green pellet as this batch green pellets, unit is inferior/0.5m.
In order further to understand the present invention, pellet ore pre-heating method provided by the invention and preparation method are described below in conjunction with embodiment.Describe just to further specifying feature and advantage of the present invention but should be appreciated that these, rather than to the restriction of claim of the present invention.
Embodiment 1
According to a kind of embodiment design grate kiln of pellet device of the present invention, main design parameters is following:
Chain-grate machine specification: 4m (width) * 37.5m (length), the first dryer section length 7.5m, 230 ℃ of design temperatures, charge level wind speed 1.5m/s, the temperature of first dryer section is through the air quantity control of the civilian described hotblast stove 13b in control back; The second dryer section length 7.5m, 360 ℃ of design temperatures, charge level wind speed are 1.2m/s; The first preheating section length 7.5m, 700 ℃ of design temperatures, charge level wind speed are 1.0m/s; The second preheating section length 15m, 1200 ℃ of design temperatures, charge level wind speed are 0.7m/s; First step drying and second stage drying are the exhausting drying mode.
Rotary kiln design temperature: 1350 ℃.
The central cooler specification: diameter is 12.5m, and width is 2.2m, and active cooling surface is long-pending to be 68m
2The cooling area 25m of the first cooling section C 1
2, the cooling area 23m of second cooling section
2, the cooling area 20m of the 3rd cooling section
2
Be connected with the first air supply duct 13a between the exhaust side of second cooling section and first preheating section; Be connected with the second air supply duct 11a between the exhaust side of second preheating section and second dryer section; Be connected with the 3rd air supply duct 13c between the exhaust side of the 3rd cooling section and first dryer section, the 3rd air supply duct is provided with hotblast stove 13b.
The flue gas that first cooling section is discharged is admitted to rotary kiln to pellet roasting, and the flue gas that rotary kiln is discharged is admitted to second preheating section pelletizing is carried out preheating; Second cooling section discharge flue gas is admitted to first preheating section through the first air supply duct 13a pelletizing is carried out the transition preheating; The flue gas of discharging from the 3rd cooling section with send into hot blast from hotblast stove 13b and mix after; Gas mixture is sent into first dryer section pelletizing is carried out first step drying, and the flue gas that second preheating section is discharged is admitted to second dryer section pelletizing is carried out second stage drying.
Raw material: rhombohedral iron ore 100 weight parts, wilkinite 1 weight part and the water got after roller grinds are made ball in granulating disc.Green pellets to obtaining is tested, and performance index are following: dropping strength is 6.5 times/0.5m, and water cut is 9.5wt%, and burst temperature is 460 ℃.
Green pellets is sent into grate kiln carry out preheating and roasting, the bed thickness in chain-grate machine is 165mm, and the chain-grate machine running speed is 2.5m/min.
From more than pelletizing average intensity 2000N/ of cooler discharge, output is 180t/ hour.
Embodiment 2
Be with the difference of embodiment 1, changed following process design parameter: 220 ℃ of the first dryer section design temperatures, charge level wind speed 1.4m/s; 340 ℃ of the second dryer section design temperatures, charge level wind speed are 1.3m/s; 750 ℃ of the first preheating section design temperatures, charge level wind speed are 1.1m/s; 1200 ℃ of the second preheating section design temperatures, charge level wind speed are 0.7m/s; First step drying and second stage drying are the exhausting drying mode; Rotary kiln design temperature: 1350 ℃; Other parameters are identical with embodiment 1.
Raw material: get rhombohedral iron ore 100 weight parts after roller grinds, wilkinite 1 weight part, Wingdale 6 weight parts and water are made ball in granulating disc.Green pellets to obtaining is tested, and performance index are following: dropping strength is 7.3 times/0.5m, and water cut is 10.6wt%, and burst temperature is 430 ℃.
Green pellets is sent into grate kiln carry out preheating and roasting, the bed thickness in chain-grate machine is 160mm, and the chain-grate machine running speed is 2.2m/min.
From more than pelletizing average intensity 2100N/ of cooler discharge, output is 160t/ hour.
Compared with prior art; After the present invention is heated to first step exsiccant design temperature through said hotblast stove 13b with the flue gas of the 3rd section discharge; All recovery is used to carry out first step drying, has therefore avoided the loss of system capacity, and can competent air quantity be provided for first step drying.In addition, in the prior art, the part of smoke of the 3rd cooling section directly is discharged in the atmosphere through arranging the chimney that looses, and the present invention all reclaims the flue gas of the 3rd cooling section, therefore can avoid contaminate environment.
More than pellet ore pre-heating method provided by the invention, preparation method and device have been carried out detailed introduction.Used concrete example among this paper principle of the present invention and embodiment are set forth, the explanation of above embodiment just is used for helping to understand method of the present invention and core concept thereof.Should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the principle of the invention, can also carry out some improvement and modification to the present invention, these improvement and modification also fall in the protection domain of claim of the present invention.
Claims (9)
1. pellet ore pre-heating method; Comprise: green pellets is sent into chain-grate machine carry out first step drying, second stage drying, first step preheating, second stage preheating successively; Said first step drying is that exhausting is dry, and the water-content of said green pellets is 7wt%~12.5wt%;
The flue gas of being discharged by rotary kiln when carrying out the preheating of the said second stage is as hot air source, and said rotary kiln is used for the preheating pelletizing of roasting after the chain-grate machine preheating;
The flue gas of being discharged by the second stage cooling of cooler when carrying out said first step preheating is as hot air source; Said cooler is used to cool off the roasting pelletizing behind rotary kiln baking, and said cooler carries out first step cooling, second stage cooling, third stage cooling successively to the roasting pelletizing;
Carry out the said second stage when dry by the flue gas of discharging after the preheating of the second stage as hot air source;
Carry out flue gas that the said first step discharged by the third stage cooling of cooler when dry as hot air source, the flue gas that said third stage cooling is discharged is heated to the design temperature T of first step when dry
DD1, the said design temperature T of first step when dry that carry out
DD1Burst temperature T with green-ball
ExplosionSatisfy following condition: T
Explosion-250 ℃≤T
DD1≤T
Explosion-100 ℃; First step exsiccant charge level wind speed is 0.2m/s~2.5m/s, and be 1.5min~5min time of drying;
Design temperature T when the said second stage is dry
DD2Satisfy following condition: T
Explosion-100 ℃≤T
DD2≤T
Explosion-20 ℃; Second stage exsiccant charge level wind speed is 0.2m/s~2.5m/s, and be 1.5min~5min time of drying;
The flue gas that said first step cooling is discharged is admitted to the rotary kiln baking pelletizing;
Behind flue gas heating to the first step exsiccant design temperature that said third stage cooling is discharged, all recovery is used for first step drying;
The iron-bearing material for preparing said green pellets comprises the rhombohedral iron ore of 70wt% at least.
2. pre-heating mean according to claim 1 is characterized in that the flue gas that said third stage cooling is discharged heats through hotblast stove.
3. pre-heating mean according to claim 1 is characterized in that, the additive for preparing said green pellets comprises: one or more in Wingdale, slaked lime, rhombspar, the forsterite.
4. pre-heating mean according to claim 1 is characterized in that, prepares said green pellets raw material and joins charcoal in also comprising, joins charcoal in said to comprise: one or more in hard coal, coke, refinery coke, the charcoal.
5. pre-heating mean according to claim 4 is characterized in that, the iron-bearing material for preparing said green pellets also comprises one or more in sulfate slag, magnetite, spathic iron ore, limonite, the pyrite.
6. the preparation method of a pellet comprises step:
A) green pellets is sent into chain-grate machine and carry out first step drying, second stage drying, first step preheating, second stage preheating successively, the iron-bearing material for preparing said green pellets comprises at least 85% rhombohedral iron ore, and the water-content of said green pellets is 7wt%~12.5wt%;
B) the preheating pelletizing after the preheating of the second stage is sent into rotary kiln baking;
C) the roasting pelletizing after the roasting is sent into cooler successively and carry out first step cooling, second stage cooling, third stage cooling;
The flue gas that said first step cooling is discharged is admitted to the rotary kiln baking pelletizing; The flue gas of discharging from rotary kiln carries out second stage preheating; The flue gas that second stage preheating is discharged carries out second stage drying; The flue gas that second stage cooling is discharged is used to carry out first step preheating, the design temperature T the when flue gas that third stage cooling is discharged is heated to first step drying
DD1The back is all reclaimed and is used to carry out first step drying, the said design temperature T of first step when dry that carry out
DD1Burst temperature T with green-ball
ExplosionSatisfy following condition: T
Explosion-250 ℃≤T
DD1≤T
Explosion-100 ℃; First step exsiccant charge level wind speed is 0.2m/s~2.5m/s, and be 1.5min~5min time of drying;
Design temperature T when the said second stage is dry
DD2Satisfy following condition: T
Explosion-100 ℃≤T
DD2≤T
Explosion-20 ℃; Second stage exsiccant charge level wind speed is 0.2m/s~2.5m/s, and be 1.5min~5min time of drying.
7. preparation method according to claim 6 is characterized in that the flue gas that said third stage cooling is discharged heats through hotblast stove.
8. device for preparing pellet; Comprise: the cooler of the rotary kiln of the chain-grate machine of preheating green pellets, the pelletizing of roasting after the chain-grate machine preheating, the pelletizing of cooling behind rotary kiln baking, the water-content of the green pellets of said chain-grate machine preheating is 7wt%~12.5wt%;
Said chain-grate machine is divided into first dryer section, second dryer section, first preheating section, second preheating section successively from infeed end one side, is respectively applied for to carry out first step drying, second stage drying, first step preheating, second stage preheating;
Said cooler is divided into first cooling section, second cooling section, the 3rd cooling section successively from infeed end one side, is respectively applied for to carry out first step cooling, second stage cooling, third stage cooling;
The exhaust side of said second cooling section comprises first air supply duct that is communicated with first preheating section; The exhaust side of said second preheating section comprises second air supply duct that is communicated with second dryer section; The exhaust side of said the 3rd cooling section comprises the 3rd air supply duct that is communicated with first dryer section; Said the 3rd air supply duct is provided with heating unit, the design temperature T the when hot blast that said the 3rd cooling section is discharged is heated to first step drying
DD1After all be delivered to first dryer section and carry out first step drying by said the 3rd air supply duct;
The flue gas of discharging from said first cooling section is recovered to rotary kiln pelletizing is carried out roasting, and the flue gas of discharging from rotary kiln is admitted to second preheating section pelletizing is carried out second stage preheating;
Design temperature T when the said first step is dry
DD1Burst temperature T with green-ball
ExplosionSatisfy following condition: T
Explosion-250 ℃≤T
DD1≤T
Explosion-100 ℃; First step exsiccant charge level wind speed is 0.2m/s~2.5m/s, and be 1.5min~5min time of drying;
Design temperature T when the said second stage is dry
DD2Satisfy following condition: T
Explosion-100 ℃≤T
DD2≤T
Explosion-20 ℃; Second stage exsiccant charge level wind speed is 0.2m/s~2.5m/s, and be 1.5min~5min time of drying.
9. device according to claim 8 is characterized in that said heating unit is a hotblast stove.
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