CN115927843A - Low-temperature consolidated composite pellet, preparation method thereof and drying consolidation method - Google Patents
Low-temperature consolidated composite pellet, preparation method thereof and drying consolidation method Download PDFInfo
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- 239000008188 pellet Substances 0.000 title claims abstract description 262
- 238000001035 drying Methods 0.000 title claims abstract description 177
- 238000007596 consolidation process Methods 0.000 title claims abstract description 128
- 239000002131 composite material Substances 0.000 title claims abstract description 76
- 238000000034 method Methods 0.000 title claims description 60
- 238000002360 preparation method Methods 0.000 title abstract description 10
- 238000004519 manufacturing process Methods 0.000 claims abstract description 20
- 230000005672 electromagnetic field Effects 0.000 claims description 90
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 85
- 239000003795 chemical substances by application Substances 0.000 claims description 71
- 239000002994 raw material Substances 0.000 claims description 41
- 229910052742 iron Inorganic materials 0.000 claims description 40
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 38
- 239000011575 calcium Substances 0.000 claims description 24
- 230000009467 reduction Effects 0.000 claims description 23
- 239000000920 calcium hydroxide Substances 0.000 claims description 21
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 21
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical group [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 20
- 238000002156 mixing Methods 0.000 claims description 20
- 238000000605 extraction Methods 0.000 claims description 19
- 239000000203 mixture Substances 0.000 claims description 17
- 229910052720 vanadium Inorganic materials 0.000 claims description 17
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 claims description 17
- 239000011230 binding agent Substances 0.000 claims description 16
- 239000000446 fuel Substances 0.000 claims description 14
- 239000002893 slag Substances 0.000 claims description 14
- 239000000428 dust Substances 0.000 claims description 13
- 238000005453 pelletization Methods 0.000 claims description 13
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 7
- 239000002245 particle Substances 0.000 claims description 7
- 229910052725 zinc Inorganic materials 0.000 claims description 7
- 239000011701 zinc Substances 0.000 claims description 7
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical group OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 claims description 6
- 229910000831 Steel Inorganic materials 0.000 claims description 6
- 239000000571 coke Substances 0.000 claims description 6
- 239000010959 steel Substances 0.000 claims description 6
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 5
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 5
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 5
- 229910052802 copper Inorganic materials 0.000 claims description 5
- 239000010949 copper Substances 0.000 claims description 5
- 239000004571 lime Substances 0.000 claims description 5
- 229910052889 tremolite Inorganic materials 0.000 claims description 5
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 4
- 229910052612 amphibole Inorganic materials 0.000 claims description 4
- 241000125205 Anethum Species 0.000 claims description 3
- 238000002485 combustion reaction Methods 0.000 claims description 3
- 229910052888 grunerite Inorganic materials 0.000 claims description 3
- 239000004449 solid propellant Substances 0.000 claims description 3
- 238000003756 stirring Methods 0.000 claims description 2
- LDHBWEYLDHLIBQ-UHFFFAOYSA-M iron(3+);oxygen(2-);hydroxide;hydrate Chemical compound O.[OH-].[O-2].[Fe+3] LDHBWEYLDHLIBQ-UHFFFAOYSA-M 0.000 claims 1
- 238000006243 chemical reaction Methods 0.000 abstract description 35
- 239000002910 solid waste Substances 0.000 abstract description 12
- 239000007789 gas Substances 0.000 description 58
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 38
- 230000008569 process Effects 0.000 description 34
- 239000000463 material Substances 0.000 description 27
- 238000006722 reduction reaction Methods 0.000 description 26
- 238000007602 hot air drying Methods 0.000 description 21
- 229910000019 calcium carbonate Inorganic materials 0.000 description 19
- 239000003245 coal Substances 0.000 description 16
- 239000000126 substance Substances 0.000 description 15
- 229910052783 alkali metal Inorganic materials 0.000 description 11
- 150000001340 alkali metals Chemical class 0.000 description 11
- 230000000694 effects Effects 0.000 description 10
- 238000002474 experimental method Methods 0.000 description 10
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 10
- 238000004939 coking Methods 0.000 description 9
- 238000011946 reduction process Methods 0.000 description 9
- 230000009471 action Effects 0.000 description 8
- 229910052799 carbon Inorganic materials 0.000 description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 7
- 238000000354 decomposition reaction Methods 0.000 description 7
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 6
- 229910002091 carbon monoxide Inorganic materials 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 6
- 229910052739 hydrogen Inorganic materials 0.000 description 6
- 229910052500 inorganic mineral Inorganic materials 0.000 description 6
- 235000013980 iron oxide Nutrition 0.000 description 6
- 239000011707 mineral Substances 0.000 description 6
- 235000010755 mineral Nutrition 0.000 description 6
- 229910052791 calcium Inorganic materials 0.000 description 5
- 150000001875 compounds Chemical class 0.000 description 5
- 239000013081 microcrystal Substances 0.000 description 5
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 4
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 4
- 238000009792 diffusion process Methods 0.000 description 4
- 229910052708 sodium Inorganic materials 0.000 description 4
- 239000011734 sodium Substances 0.000 description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 239000001569 carbon dioxide Substances 0.000 description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 description 3
- 239000003638 chemical reducing agent Substances 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 238000005272 metallurgy Methods 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 241001391944 Commicarpus scandens Species 0.000 description 2
- 238000003723 Smelting Methods 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 239000000292 calcium oxide Substances 0.000 description 2
- 235000012255 calcium oxide Nutrition 0.000 description 2
- 239000004568 cement Substances 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 2
- 238000001465 metallisation Methods 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 239000002028 Biomass Substances 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- 229910000805 Pig iron Inorganic materials 0.000 description 1
- YZCKVEUIGOORGS-IGMARMGPSA-N Protium Chemical compound [1H] YZCKVEUIGOORGS-IGMARMGPSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000033558 biomineral tissue development Effects 0.000 description 1
- 238000003763 carbonization Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000011278 co-treatment Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 238000002309 gasification Methods 0.000 description 1
- 238000012933 kinetic analysis Methods 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000010310 metallurgical process Methods 0.000 description 1
- VUZPPFZMUPKLLV-UHFFFAOYSA-N methane;hydrate Chemical compound C.O VUZPPFZMUPKLLV-UHFFFAOYSA-N 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 150000003681 vanadium Chemical class 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Classifications
-
- Y—GENERAL 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Processing Of Solid Wastes (AREA)
Abstract
The invention provides a low-temperature consolidated composite pellet and a preparation method thereof. By changing the components of the pellet, the type of a carbonation consolidation reaction model is changed, the carbonation reaction efficiency is greatly improved, the pellet has high strength in the pellet production stage, the drying and consolidation process and after consolidation, the production efficiency and the pellet strength are comprehensively considered, the metallurgical solid waste carbonation consolidation production efficiency is finally improved, and the production period is shortened.
Description
Technical Field
The invention relates to a pellet and a preparation method thereof, in particular to a pellet adopting low-temperature consolidation and a preparation method and a drying and consolidating method thereof, belonging to the technical field of metallurgy.
Background
The process for extracting metallic iron from iron-containing minerals (mainly iron oxides) mainly comprises a blast furnace method, a direct reduction method, a smelting reduction method and the like. From the metallurgical point of view, iron making is the reverse of iron rusting and gradual mineralization, and simply, pure iron is reduced from iron-containing compounds. A process for producing pig iron by reducing iron ore with a reducing agent at elevated temperature. The main raw materials for iron making are iron ore and coke; the function of the coke is to provide heat and produce the reductant carbon monoxide.
The metallurgical solid waste generally contains higher alkali metals, so that the alkali metals are difficult to return to the metallurgical process for direct utilization and need to be removed in advance. In the process of removing alkali metal from metallurgical solid waste containing alkali metal by calcific oxidation roasting or calcific reduction roasting, a large amount of calcium-containing substances are required to be added for replacing the alkali metal in complex multi-element solid solution under high-temperature oxidation or reduction atmosphere, so that the alkali metal is converted into a simple alkali metal-containing compound, and then the alkali metal-containing compound is removed by leaching or reduction volatilization. The calcium-containing pellet needs to be dried firstly before high-temperature roasting, and ensures that the pellet has certain compression resistance and falling strength, and the green pellet contains calcium hydroxide with a high proportion, so that the method of carbonation consolidation is suitable for improving the strength of the dried pellet. The carbonization and consolidation process of metallurgy solid waste mainly generates Ca (OH) 2 With CO 2 Combined formation of CaCO 3 The traditional pellet carbonation consolidation process is carried out at lower temperature (50-70 ℃) and more concentrated CO 2 Atmosphere (25% -30%) and it is necessary to keep the pellets containing a certain amount of moisture or under a moisture environment. CO in the reaction process atmosphere 2 Diffusing from the outside of the pellet to the inside of the pellet and contacting and reacting with calcium hydroxide in the pellet, belonging to a typical unreacted nuclear model, which easily causes the outer surface of the pellet to firstly form a compact calcium carbonate film to block CO 2 Gas diffuses into the pellet to greatly slow the whole carbonation process of the pellet, and in order to ensure that the carbonation reaction rate is slowed down without too fast loss of water in the pellet and that when the microcrystalline calcium carbonate strength is not established due to too fast drying, the pellet strength in the drying and consolidation process is difficult to maintain by the dried calcium hydroxide, and the temperature in the carbonation consolidation process needs to be maintained at a lower temperature, so that the drying and consolidation efficiency is extremely low, and the pellet can reach the required strength by tens of hours of drying and consolidation or long-time stacking and slow reaction. If the reaction efficiency is to be improved, higher temperatures or very high concentrations of CO are required 2 The conditions are harsh, and the pellet strength in the drying and consolidation process is difficult to ensure, so that the pellet height in the drying and consolidation process is severely limited, and the production efficiency is highNor high. Therefore, the traditional carbonation consolidation process has difficulty in balancing the green strength, the dry consolidation process ball strength, the dry ball strength and the production efficiency.
In order to realize the low-temperature consolidation of the metallurgical solid waste, researchers and practitioners propose some technical measures. Patent CN102732670A proposes a recycling method for treating iron-containing dust by using a carbonation process, which comprises mixing the iron-containing dust and active lime uniformly for pelletizing, and then carrying out CO treatment at 500-600 deg.C 2 In the gas environment with the concentration of more than 50 percent, the carbonation consolidation is carried out in the carbonation reaction tank, so that the pellets have certain strength and replace a calcium-containing flux for converter steelmaking, and the converter steelmaking period is shortened. Patent CN1842604B proposes a self-reducing cold-bonded pellet and a manufacturing method thereof, which adopts cement clinker as a binder, mixes the cement clinker with mineral powder for pelletizing, and then introduces CO into a curing device at the temperature of 100-300 DEG C 2 And (5) solidifying for 24-96 h by using gas, so that the pellets have higher strength. In "research analysis of slagging Agents for converter preparation by carbonation of converter dust", zhang Shixia, published in Shanxi Metallurgical (2012, 194 (6): 28-29), converter dust and lime are pressed into briquettes with a pressure of more than 2000N, and the CO is then reduced at 75% C at a temperature of 600 ℃% 2 Reacting in the gas for 60min to obtain the block mass with the compressive strength more than 100N, so as to meet the requirement of converter smelting on the slag former.
Carbonation consolidation of the prior art by CO 2 The gas internal diffusion is controlled, the reaction speed is low, and the internal carbonation degree is low. In the carbonation consolidation process, ca (OH) 2 Reacted CO 2 From the reaction atmosphere, the gas gradually diffuses from the outside of the pellet to the inside of the pellet and participates in the reaction, belongs to a typical unreacted nuclear model, and the outer layer of the pellet firstly generates carbonation reaction to form a compact calcium carbonate film, so that the gas is prevented from further diffusing to the inside of the pellet, and the internal carbonation reaction is slow and the reaction degree is low.
The production efficiency and pellet strength of the prior art can not be considered simultaneously. The pellet contains partial water or is one of the necessary conditions for carbonation consolidation reaction in water vapor environment, and in order to ensure that the water in the pellet is not lost too fast, the existing carbonation consolidation reactionAt lower temperatures, which can reduce the carbonation reaction rate, require tens of hours for dry consolidation or long-term slow reaction in stockpiling, resulting in low production efficiency. If in the presence of steam, raising the reaction temperature and using CO of very high purity 2 Gas improves the carbonation consolidation speed, can lead to the inside calcium hydroxide of pellet to dewater fast, and the calcium hydroxide intensity of dry state is low, and the inside calcium carbonate crystallite of dry pellet after the moisture desorption fast has not developed sufficiently yet, can not provide intensity support, and the intensity of dry calcium hydroxide bonding bridge is extremely low, leads to the drying process pellet intensity extremely low, and the bed of material height of dry consolidation process is seriously restricted, and easily produces a large amount of powder, also can cause production efficiency low.
The calcium carbonate microcrystals in the conventional heating environment in the prior art are slow in development and low in strength, so that the strength of the carbonated consolidated sphere is low. The strength of the carbonated consolidated pellet is provided by gradual formation and growth of calcium carbonate microcrystals generated by reaction, the new calcium carbonate microcrystals automatically grow up in a conventional heating environment at a lower speed, the temperature in the pellet is low, the carbonation reaction is slow, the amount of the new calcium carbonate is less, and the strength is lower. The consolidated pellets are easy to form a double-layer structure, the carbonation degree of the outer layer is high, the strength is high, the carbonation degree of the inner core is low, the strength is low, the falling strength of the hard-outer loose double-layer pellets is poor, the pellets are extremely easy to break in the belt transferring and falling process, a large amount of broken pellets and powder are produced, and the production efficiency is influenced.
Disclosure of Invention
Aiming at the problems existing in the prior art: the carbonation consolidation process is carried out in an unreacted nuclear model, CO 2 Gradually diffuse from the outside of the pellet to the inside of the pellet, and the outside of the pellet firstly generates carbonation reaction to form a compact calcium carbonate film which seriously prevents CO 2 The gas diffuses into the pellet, which affects the pellet strength. If the pellets are dried and consolidated at a higher temperature, the moisture in the pellets is quickly evaporated, the carbonation reaction is not timely carried out, the bonding strength among the pellet particles is only provided by the dried calcium hydroxide, the strength is extremely poor, and the pellets are very easy to break. Therefore, the traditional carbonation consolidation reaction can only be slowly carried out at a lower temperature, and is in-situThe ball strength, the ball strength in the drying and consolidation process, the dry ball strength and the production efficiency are difficult to be considered, so that the technical problems of low production efficiency and low pellet strength are caused.
Firstly, the method comprises the following steps: the invention provides a low-temperature consolidated composite pellet and a preparation method thereof, which change the type of a carbonation consolidation reaction model by changing the components of the pellet, greatly improve the carbonation reaction efficiency, ensure that the pellet has high strength in the pellet production stage, the drying consolidation process and after consolidation, comprehensively consider the production efficiency and the pellet strength, finally improve the production efficiency of metallurgy solid waste carbonation consolidation and shorten the production period.
Secondly, the method comprises the following steps: the invention also changes the drying and consolidation mode of the pellets, and is cooperated with the C-H-O low-temperature release agent in the pellets through the action of the electromagnetic field, so that the pellets release CO from the interior of the pellets in the consolidation process 2 And H 2 And O, forming consolidation from inside to outside, and further enhancing the strength of the pellets.
Thirdly, the method comprises the following steps: the composite pellet prepared by the technical scheme of the invention also contains H-O high-temperature gas slow-release agent, and the H-O high-temperature gas slow-release agent in the pellet is decomposed to release H in the reduction stage of the composite pellet prepared by the technical scheme of the invention 2 O, and the carbon added in the pellets are subjected to gasification reaction to form reducing gas H 2 And CO, the partial pressure of the reducing gas in the pellets is improved, and uniform and rapid low-temperature reduction in the pellets is realized.
According to a first embodiment provided by the present invention, a low temperature consolidated composite pellet is provided.
A low temperature consolidated composite pellet, the composite pellet comprising: iron-containing raw materials, fuel, a binder and a C-H-O low-temperature releasing agent.
Preferably, the composite pellet also comprises a H-O high-temperature gas slow release agent.
In the invention, the C-H-O low-temperature releasing agent is bicarbonate, or the C-H-O low-temperature releasing agent is a mixture of bicarbonate and carbonate.
Preferably, the C-H-O low-temperature releasing agent is Ca (HCO) 3 ) 2 、Mg(HCO 3 ) 2 、Ca(HCO 3 ) 2 -FeCO 3 、Mg(HCO 3 ) 2 -FeCO 3 、Ca(HCO 3 ) 2 -Mg(HCO 3 ) 2 Or Ca (HCO) 3 ) 2 -FeCO 3 -Mg(HCO 3 ) 2 。
In the invention, the H-O high-temperature gas slow release agent is one or more of iron amphibole, hydrated iron oxide, dill and tremolite.
Preferably, the H-O high-temperature gas slow release agent is Fe 7 Si 8 O 22 (OH) 2 、Fe 2 O 3 ·nH 2 O、Fe 18 Si 12 O 40 (OH) 10 、2CaO·5MgO·8SiO 2 ·H 2 One or more of O.
In the invention, the weight ratio of the iron-containing raw material, the fuel, the binder and the C-H-O low-temperature releasing agent in the composite pellet is (100) from 0.5 to 30.
In the present invention, the weight ratio of the addition amount of the H — O high-temperature gas release agent to the iron-containing raw material is from 0.1 to 50, preferably from 5 to 40, and more preferably from 10 to 30.
In the present invention, the iron-containing raw material is slag and/or metallurgical dust.
Preferably, the iron-containing raw material is one or more of vanadium extraction tailings, copper slag, steel slag and zinc-containing dust.
Preferably, the granularity of the C-H-O low-temperature releasing agent is-200 meshes or more than 50 percent, more preferably-325 meshes or more than 80 percent.
Preferably, the granularity of the H-O high-temperature gas slow-release agent is-200 meshes or more than 50 percent, more preferably-325 meshes or more than 80 percent;
in the present invention, the binder is calcium hydroxide.
In the present invention, the fuel is a carbonaceous solid fuel.
Preferably, the particle size of the composite pellet is 1-20mm, preferably 2-10mm, and more preferably 3-8mm.
According to a second embodiment of the present invention, a method for preparing a composite pellet is provided.
A method of making the composite pellet of the first embodiment, comprising the steps of:
(1) Uniformly mixing the C-H-O low-temperature release agent and the high-temperature gas slow release agent to obtain a mixture I;
(2) Uniformly mixing an iron-containing raw material, fuel and a binder to obtain a mixture II;
(3) And mixing the mixture I and the mixture II, adding water, stirring and mixing uniformly, and pelletizing to obtain the composite pellet.
In the present invention, the amount of water added is 3 to 20, preferably 5 to 15% of the total weight of the composite pellet.
Preferably, atomized water is used as the water added in step (3).
According to a third embodiment of the present invention, a method for dry consolidation of composite pellets is provided.
In the method for drying and consolidating the composite pellets in the first embodiment or the composite pellets prepared in the second embodiment, the composite pellets are dried and consolidated by adopting an electromagnetic field, or hot air pre-drying and electromagnetic field drying and consolidation are adopted.
Preferably, in the dry consolidation step, a CO-containing gas is introduced 2 And water vapor.
Preferably, the CO-containing component 2 The gas with steam is added with steam and CO 2 Hot air after combustion, blast furnace gas/coke oven gas/converter gas, direct reduction hot tail gas, lime kiln hot tail gas, etc.
In the present invention, the CO-containing component 2 And water vapor, CO 2 The volume concentration of (A) is 1% to 50%, preferably 5 to 40%, more preferably 10 to 30%. Containing CO 2 The humidity of the gas with water vapor is 10g/m 3 ～100g/m 3 Preferably 15g/m 3 ～80g/m 3 More preferably 20g/m 3 ～50g/m 3 。
In the invention, when the electromagnetic field is adopted for drying and consolidating the composite pellets:the temperature of electromagnetic field drying is 100-500 deg.C, preferably 300-400 deg.C. The drying and consolidation time is 10min to 60min, preferably 20min to 40min. The power density of the electromagnetic field is 5kw/m 3 ～50kw/m 3 Preferably 20kw/m 3 ～30kw/m 3 。
In the invention, when the hot air pre-drying and the electromagnetic field drying are adopted to solidify the composite pellets:
the temperature of the hot air is 100 to 500 ℃, preferably 200 to 400 ℃. The hot air pre-drying time is 10min to 60min, preferably 10min to 20min. The water content in the composite pellets after the hot air pre-drying is 2-8%, preferably 3-6%.
The drying temperature of the electromagnetic field is 100-500 ℃, preferably 300-400 ℃. The drying and consolidation time is 5 min-40 min, preferably 10 min-30 min. The power density of the electromagnetic field is 5kw/m 3 ～50kw/m 3 Preferably 20kw/m 3 ～30kw/m 3 。
Aiming at the problem that in the prior art, the pellets are in a drying and consolidating process, CO 2 The gas can only diffuse from the outside of the pellet to the inside of the pellet, so that the binder (such as calcium hydroxide) on the outer layer of the outer pellet is preferentially mixed with CO 2 React to form a compact calcium carbonate layer, which hinders CO 2 The gas continuously diffuses into the pellet, so that calcium carbonate cannot be formed inside the pellet, and the overall strength of the pellet is influenced. The first substance added in the pelletizing process is a C-H-O low-temperature releasing agent, and in the pellet drying and consolidating process, the C-H-O low-temperature releasing agent in the pellet core (inside) can release CO under the low-temperature condition of drying and consolidating 2 And H 2 O, release CO 2 And H 2 The O reacts with the binder (such as calcium hydroxide) in the pellets to form a calcium carbonate consolidation structure uniformly in the whole pellets; so that calcium carbonate concretion with higher strength is formed at each position in the whole pellet, and the strength of the whole pellet is improved. In the technical scheme of the invention, the C-H-O low-temperature release agent among the raw material particles is converted into CO in the drying and consolidation process 2 And H 2 O, directly providing CO required for the internal carbonation reaction of the pellets 2 Gas and H 2 The environment of O steam is that,changes the prior unreacted nuclear model and avoids the traditional CO 2 The condition that the carbon dioxide needs to diffuse from the outside of the pellet to enter the inside of the pellet, the outside and the inside of the pellet are carbonated synchronously, the influence that the dense calcium carbonate film on the outer layer hinders the gas diffusion is avoided, and the CO is reduced 2 Diffusion resistance inside the pellets. Furthermore, from reaction kinetic analysis, compared to CO 2 Gas diffuses from the outside of the pellet to the inside of the pellet, and CO is released from the inside of the pellet by adopting the technical scheme of the invention 2 And H 2 O, CO inside the pellets 2 And H 2 The outward diffusion of O is much easier, so that the binder (such as calcium hydroxide) in the pellets reacts with CO in the presence of water vapor 2 The reaction is easier, and the obtained calcium carbonate consolidation material is more uniform.
In the invention, the C-H-O low-temperature releasing agent is solid at normal temperature, and in the drying consolidation process and the heating process, the bicarbonate or carbonate is heated and decomposed to release carbon dioxide and/or water. The released carbon dioxide reacts with the binder in the pellets under the action of water vapor to form a compound for consolidation. For example, ca (HCO) as used herein 3 ) 2 Begins to decompose at 250 ℃ with evolution of CO 2 And H 2 O；Mg(HCO 3 ) 2 Begin to decompose at about 90 ℃ and release CO 2 And H 2 O；FeCO 3 Begin to decompose at 320 ℃ releasing CO 2 . The C-H-O low-temperature releasing agent is solid at the lower part in the normal temperature state, so that the C-H-O low-temperature releasing agent is convenient to be mixed with the iron-containing raw material for pelletizing; mixing the C-H-O low-temperature release agent with the iron-containing raw material and other additives for pelletizing to form pellets, gradually beginning to decompose under the condition of temperature rise in the drying and consolidation process to release CO 2 And H 2 O, realizes the self-release of CO in the drying and consolidation process of the pellets 2 And H 2 The technical effect of O and the introduction of CO into the outside 2 And H 2 The mode of O is different, and the pellet releases CO from the interior of the pellet 2 And H 2 And O, the consolidation process is carried out simultaneously inside and outside the pellet, so that the pellet after drying and consolidation is of a structure with uniform strength from inside to outside, and the technical problem of hard outside and loose inside is solved. At the same time, useThe decomposition temperature of the C-H-O low-temperature releasing agent cannot be too high because the drying temperature of the pellets is generally controlled below 500 ℃ (preferably below 400 ℃), and if bicarbonate or carbonate with too high decomposition temperature (above 500 ℃) is adopted, CO cannot be decomposed and released in the drying and consolidation process 2 And H 2 O, thereby failing to achieve CO release from the interior of the pellets 2 And H 2 Technical purpose and effect of O. Through continuous experiments of the inventor, ca (HCO) is added in the process of preparing the pellets 3 ) 2 、Mg(HCO 3 ) 2 、Ca(HCO 3 ) 2 -FeCO 3 、Mg(HCO 3 ) 2 -FeCO 3 、Ca(HCO 3 ) 2 -Mg(HCO 3 ) 2 Or Ca (HCO) 3 ) 2 -FeCO 3 -Mg(HCO 3 ) 2 In the temperature range of the pellet drying and consolidating process, the compound or the composition can release CO 2 And H 2 O, the decomposition temperature of the substances is matched with the temperature of the drying and consolidation process, and CO begins to be released under the temperature condition of the drying and consolidation process 2 And H 2 O, CO required for the consolidation of the pellet interior 2 And H 2 O。
In the present invention, ca (HCO) 3 ) 2 -FeCO 3 Refers to Ca (HCO) 3 ) 2 And FeCO 3 Mixture of (2), mg (HCO) 3 ) 2 -FeCO 3 Refers to Mg (HCO) 3 ) 2 And FeCO 3 Mixture of (2), ca (HCO) 3 ) 2 -Mg(HCO 3 ) 2 Refers to Ca (HCO) 3 ) 2 And Mg (HCO) 3 ) 2 Mixture of (2), ca (HCO) 3 ) 2 -FeCO 3 -Mg(HCO 3 ) 2 Refers to Ca (HCO) 3 ) 2 、FeCO 3 And Mg (HCO) 3 ) 2 A mixture of (a). Experiments prove that the C-H-O low-temperature release agent in the form of the substance 6 can achieve the technical effect of the application. The dosage proportion in the mixture does not affect the effect of the technical scheme of the application.
In the present invention, the amount of fuel added may be 0.5 parts by weight, 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 12 parts by weight, 15 parts by weight, 18 parts by weight, 20 parts by weight, 23 parts by weight, 25 parts by weight, 28 parts by weight, or 30 parts by weight based on 100 parts by weight of the iron-containing raw material in the composite pellet. The amount of the binder added may be 0.1 part by weight, 0.2 part by weight, 0.5 part by weight, 0.6 part by weight, 0.8 part by weight, 1 part by weight, 1.2 parts by weight, 1.5 parts by weight, 1.8 parts by weight, 2 parts by weight, 2.3 parts by weight, 2.5 parts by weight, 2.8 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, 4.5 parts by weight, 5 parts by weight. The C-H-O low-temperature releasing agent may be added in an amount of 0.1 part by weight, 0.3 part by weight, 0.5 part by weight, 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 12 parts by weight, 15 parts by weight, 18 parts by weight, 20 parts by weight, 23 parts by weight, 25 parts by weight, 28 parts by weight, 30 parts by weight, 32 parts by weight, 35 parts by weight, 38 parts by weight, 40 parts by weight, 42 parts by weight, 45 parts by weight, 50 parts by weight.
Aiming at the problems that in the prior art, the pellets are generally dried and consolidated only by adopting a hot air drying and consolidating mode, and the hot air drying mode is adopted, so that the external surface temperature of the pellets is higher, the internal temperature of the pellets is lower, and the temperature difference is larger; in order to dry the inside of the pellet, the temperature of the outside of the pellet needs to be further increased, thereby causing CO on the appearance of the pellet 2 The calcium carbonate reacts with the adhesive quickly to form a compact calcium carbonate layer, and further prevents the formation of a consolidation structure inside the pellet. In the preferred scheme of the invention, an electromagnetic field drying and solidifying technical means is added, and an electromagnetic field drying and solidifying mode is adopted, or a hot air pre-drying and electromagnetic field drying and solidifying mode is adopted.
Compared with hot air drying which is only physical heat, the pellets are dried and consolidated in a heat transfer mode; the electromagnetic field is an energy field, and the electromagnetic field can directly act on the interior of the pellet to excite the decomposition of the C-H-O low-temperature releasing agent in the interior of the pellet. Thereby, the external and internal temperature of the pellet can be ensured to be uniform by the way of heating, drying and consolidating the pellet by the electromagnetic fieldThereby allowing both the exterior and interior of the pellets to be simultaneously dried and consolidated. By means of electromagnetic field heating and adding C-H-O low temperature releasing agent into the pellet, the electromagnetic field acts directly on the C-H-O low temperature releasing agent, and the C-H-O low temperature releasing agent is decomposed synchronously to release CO while drying 2 And H 2 O, therefore, drying and consolidation are performed simultaneously. The electromagnetic field not only plays a role in heating, but also ensures the uniformity of the temperature inside and outside the pellet, and further ensures that the C-H-O low-temperature release agents at different positions of the pellet are simultaneously decomposed, so that all the positions of the pellet are simultaneously consolidated, and the composite pellet with uniform strength is formed.
The carbonation consolidation process adopts a consolidation mode under the action of a high-frequency electromagnetic field, and the C-H-O low-temperature release agent in the pellets is uniformly decomposed and converted into CO under the action of the high-frequency electromagnetic field 2 And H 2 O, the problem that the reaction of the outer layer and the inner material of the pellet is asynchronous due to the traditional outside-in heat conduction mode is avoided, so that the temperature and the CO inside and outside the pellet are both satisfied 2 The atmosphere condition and the carbonation reaction rate are consistent, and a double-layer structure with hard outside and loose inside is not generated. In addition, under the action of high-frequency electromagnetic field, high-temperature and high-CO are formed in micro-area in the pellet 2 The reaction environment of high water vapor and high calcium is adopted, the carbonation reaction is rapidly carried out to generate calcium carbonate microcrystals, the high-frequency electromagnetic field can drive mass point migration, the microcrystals rapidly grow up, adjacent particles are tightly connected together, and high-strength guarantee is provided for the pellets.
Therefore, the composite pellet is of a homogeneous structure by the technical means of the electromagnetic field and the C-H-O low-temperature releasing agent, the technical problem of mass imbalance caused by pellet layering is solved, the high-strength structure is guaranteed to be arranged inside and outside the pellet, and the synergistic effect is achieved.
The inventor further experiments show that the drying and consolidation mode adopting hot air and electromagnetic field has a more prominent effect compared with the mode adopting hot air drying and consolidation or adopting electromagnetic field drying and consolidation alone. If the hot air drying and consolidating mode is adopted independently, the pellets are dried and consolidated in a physical heat transfer mode, the technical problem of uneven temperature inside and outside the pellets exists, and the temperature in the pellets is unevenThe consolidation strength of the sections is low. If the electromagnetic field drying and consolidating mode is independently adopted, the self-moisture in the pellet is rapidly lost, and the moisture in the gaps among the material molecules in the pellet is suddenly lost, so that the consolidating effect among the material molecules in the pellet is also influenced. Experiments show that the pellets are dried by adopting a hot air drying and solidifying mode, so that the moisture in the gaps among the material molecules in the pellets is evaporated at a slow speed, the molecules in the material are gathered slowly, and the inter-molecular distance in the material is reduced; then the CO released by the C-H-O low-temperature releasing agent is enabled to be released through the action of an electromagnetic field 2 、H 2 The O reacts with the binder to form a consolidation structure among the molecules of the material, and the strength of the obtained composite pellet is greatly improved by a drying consolidation mode combining hot air and an electromagnetic field.
Further, experiments show that the strength of the composite pellet obtained by drying and consolidating the pellet in a hot air and electromagnetic field manner is up to 300N/P or more by drying the pellet in a hot air drying and consolidating manner until the moisture in the pellet is 2% -8% (preferably 3% -6%) and then drying and consolidating in an electromagnetic field manner.
The composite pellet prepared by the invention enters a reduction process after being dried and consolidated. In the prior art, the iron-containing raw materials in the pellets are reduced through internal carbon (fuel) distribution in the pellets; the reduction process is that the internal carbon reacts with the air outside the pellet to produce CO, and the CO reduces the oxide in the pellet from the outside of the pellet; then CO diffuses from the external surface of the pellet to the interior of the pellet to reduce oxides in the pellet. In the prior art, there is also a technical scheme of hydrogen radical reduction, which specifically comprises: the oxide in the pellets is reduced by introducing hydrogen into the reduction device from the outside of the pellets, and then the hydrogen is diffused into the pellets from the outside of the pellets to reduce the oxide in the pellets. In the prior art, the reduction process is carried out from outside to inside regardless of the adoption of carbon-based reduction or hydrogen-based reduction.
The inventor of the application finds out through experiments that in the preparation process of the pellet, a substance containing crystal water (H-O high-temperature gas slow release agent) is added, and the substance containing crystal water is decomposed and released in the reduction stageOut of H 2 O，H 2 O reacts with the internal carbon in the pellet directly to generate H 2 And CO. Generation of H 2 And CO immediately generates reduction reaction with the oxide in the pellets, thereby realizing the technical effect of reducing the oxide from the interior of the pellets.
The second kind of substance added in the pelletizing process is H-O high-temperature gas slow release agent capable of releasing H under the high-temperature condition of the reduction process 2 And (O). In the reduction stage, as the temperature of the material rises, the H-O high-temperature gas slow release agent in the pellets is decomposed to release H 2 O, while the calcium carbonate formed during the consolidation process decomposes to release CO 2 The carbon added in the pellet is gasified to form reducing gas H 2 And CO, the partial pressure of the reducing gas in the pellets is increased, the reducing gas is in contact with the material particles in the pellets and carries out reduction reaction, and the condition that only CO or H is contained in the traditional reduction process is improved 2 The pellet is used as a reducing agent and is diffused from the outside to the inside of the pellet in a reaction mode, so that uniform and rapid reduction inside the pellet is realized, and a compact shell layer formed on the outer layer of the pellet in the reduction process is avoided to prevent reduction reaction from being carried out.
In the present invention, it is used to release H in the reduction stage 2 The substance O is a substance containing crystal water with a decomposition temperature of 500-1200 deg.C. The H-O high-temperature gas slow release agent is stable and does not decompose in the drying and consolidation stage (below 500 ℃); after the pellet enters the reduction process, the pellet begins to decompose and release H 2 O，H 2 The water gas reaction of O and carbon (fuel) is carried out to form H with reducibility 2 And CO, CO being characterized by a strong reducing power, H 2 The method has the advantage of high reduction speed, and the reduction rate of the pellets is greatly improved by simultaneously reducing the oxides in the pellets from the inside and the outside of the composite pellets.
Further experiments prove that the amphibole, the hydrated iron oxide, the diels and the tremolite all meet the requirements of the H-O high-temperature gas slow-release agent, and the purposes that the H is released stably in the drying and solidifying stage and is released in the reducing stage in the invention 2 The effect of O.
Further preferably, the H-O high-temperature gas slow release agent can be Fe 7 Si 8 O 22 (OH) 2 、Fe 2 O 3 ·nH 2 O、Fe 18 Si 12 O 40 (OH) 10 、2CaO·5MgO·8SiO 2 ·H 2 One or more of O. The decomposition temperature of the substances is between 500 and 1000 ℃, the substances are added in the pelletizing process of the composite pellets, the composite pellets are in a stable state through the drying and consolidation process, the substances enter the reduction process to start decomposition, and H is gradually released 2 O。
In the invention, in the composite pellet, the amount of the H-O high-temperature gas slow-release agent added may be 0.1 part by weight, 0.5 part by weight, 1 part by weight, 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, 4.5 parts by weight, 5 parts by weight, 5.5 parts by weight, 6 parts by weight, 6.5 parts by weight, 7 parts by weight, 7.5 parts by weight, 8 parts by weight, 8.5 parts by weight, 9 parts by weight, 9.5 parts by weight, 10 parts by weight, 12 parts by weight, 15 parts by weight, 18 parts by weight, 20 parts by weight, 23 parts by weight, 25 parts by weight, 28 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, 50 parts by weight based on 100 parts by weight of the iron-containing raw material.
The technical scheme provided by the invention can be used for reducing all ores, and is particularly suitable for reducing iron oxide ores. The inventor further experiments, because the metallurgical solid waste contains higher alkali metals, the alkali metals need to be treated firstly, and the metallurgical solid waste needs to be subjected to the next resource recycling. The method adopts the metallurgical solid waste as an iron-containing raw material, adds a C-H-O low-temperature releasing agent into the metallurgical solid waste, and adopts the electromagnetic field drying consolidation or adopts the mode of hot air pre-drying and electromagnetic field drying consolidation, so that the obtained composite pellet has higher strength and higher alkali metal yield. By adding the H-O high-temperature gas slow-release agent into the pellets, the metallization rate of the obtained product is greatly improved.
The technical scheme provided by the invention can be used for treating ore extraction tailings such as vanadium extraction tailings, copper slag and steel slag; it can also be used for treating dust collected in metallurgical plants, such as zinc-containing dust; used for removing zinc in the zinc-containing dust.
In the present invention, the fuel is a carbonaceous solid fuel; such as coke, coal, biomass char.
The invention provides a preparation method of composite pellets, which comprises the following detailed steps:
(1) Will contain C-H-O low temperature releasing agent (Ca (HCO) 3 ) 2 、FeCO 3 、Mg(HCO 3 ) 2 One or more of the substances) are uniformly mixed to be used as the low-temperature composite solidifying agent containing C-H-O. Releasing the high-temperature gas into the slow release agent (containing Fe) 7 Si 8 O 22 (OH) 2 、Fe 2 O 3 ·nH 2 O、Fe 18 Si 12 O 40 (OH) 10 、2CaO·5MgO·8SiO 2 ·H 2 One or more of O and the like) are uniformly mixed to be used as the high-temperature gas slow release agent containing H-O. The blending equipment can be a cylinder mixer, an intensive mixer and the like.
(2) Uniformly mixing iron-containing raw materials (such as one or more of vanadium extraction tailings, copper slag, steel slag, zinc-containing dust and other metallurgical solid wastes), fuel and a binder;
(3) And (3) uniformly mixing the mixture obtained in the step (2) with a low-temperature release agent and a high-temperature gas slow release agent, and pelletizing to obtain the composite pellet. Wherein, the mixing ratio of the metallurgical solid waste to the low-temperature releasing agent and the high-temperature gas slow-release agent is 1; the mixing equipment can be a cylinder mixer, an intensive mixer and the like; the water content of the mixed raw materials is 3 to 20 percent; the pelletizing equipment can be a disk pelletizer or a powerful disturbance pelletizer, and the pellet granularity is 1-20 mm.
Preferably, atomized water is adopted in the water adding mode in the disc pelletizing process, the atomized water is added in a raw material distribution area and a particle size area of 2-4 mm in the pellet disc respectively, and the adding amount of the atomized water is determined according to the raw material moisture and the pelletizing state.
The invention provides a drying and consolidating method of composite pellets.
Drying and solidifying the manufactured green pellets through a high-frequency electromagnetic field or drying and solidifying through hot air pre-drying and solidifying through the high-frequency electromagnetic field, wherein the drying and solidifying can be carried out in a mode of combining a high-frequency electromagnetic field with a chain grate machine, a steel mesh belt machine and the like, and the material height is 10-200 mm, preferably 100-150 mm.
Preferably, the process of drying and consolidating is carried out by introducing CO 2 And water vapor. The gas may be added steam and CO 2 Hot air after combustion, blast furnace gas/coke oven gas/converter gas, direct reduction hot tail gas, lime kiln hot tail gas, etc.; CO 2 2 The concentration is 0 to 50 percent; humidity of 10g/m 3 ～100g/m 3 Preferably 20g/m 3 ～50g/m 3 (ii) a The gas flow rate is 0.1-5 m/s.
In the invention, the temperature is 100-500 ℃ in the process of drying and solidifying by a high-frequency electromagnetic field, and the preferred temperature is 300-400 ℃; the time is 10min to 60min, preferably 20min to 40min; the power density of the high-frequency electromagnetic field is 5kw/m 3 ～50kw/m 3 Preferably 20kw/m 3 ～30kw/m 3 。
In the invention, in the process of hot air pre-drying consolidation and high-frequency electromagnetic field drying consolidation, the temperature of hot air is 100-500 ℃, and is preferably 200-400 ℃; the hot air drying time is 10min to 60min, preferably 10min to 20min; the water content of the pellets after hot air drying is 2-8%, and more preferably 4-6%. The drying temperature of the high-frequency electromagnetic field is 100-500 ℃, and preferably 300-400 ℃; the time is 5min to 40min, preferably 10min to 30min; the power density of the high-frequency electromagnetic field is 5kw/m 3 ～50kw/m 3 Preferably 20kw/m 3 ～30kw/m 3 。
The invention provides a preparation method of a low-temperature consolidated composite pellet, the diameter of the pellet is 1-20mm (preferably 2-10mm, more preferably 3-8 mm), the consolidation mode of the pellet is carbonation consolidation, compared with common carbonation low-temperature consolidation, the composite pellet has the characteristics of faster and more uniform carbonation reaction, higher pellet strength and higher production efficiency.
Compared with the prior art, the technical scheme provided by the invention has the following beneficial technical effects:
1. the invention adds C-H-O low-temperature release agent into the composite pellet, wherein the C-H-O low-temperature release agent can release CO in the low-temperature drying and consolidation process 2 And H 2 O, and can significantly improve carbonation consolidation efficiency and drynessDry consolidated sphere strength;
2. the invention adopts a carbonation consolidation method under the action of a high-frequency electromagnetic field aiming at the drying and consolidation of the composite pellets, and the C-H-O low-temperature release agent in the pellets is uniformly decomposed and converted into CO under the action of the high-frequency electromagnetic field 2 And H 2 O, the problem that the reaction of the outer layer of the pellet and the inner substance of the pellet is not synchronous due to the traditional outside-in heat conduction mode is avoided, and high-strength guarantee is provided for the pellet;
3. the composite pellet is added with the H-O high-temperature gas slow release agent which can release H in the high-temperature reduction process 2 O, and can obviously improve the partial pressure of the reducing gas in the pellet and promote the rapid progress of the reduction reaction.
Detailed Description
The technical solution of the present invention is illustrated below, and the claimed scope of the present invention includes, but is not limited to, the following examples.
Example 1
(1) Adding 80% of Ca (HCO) with-325 meshes 3 ) 2 Uniformly mixing the raw materials with vanadium extraction tailings, coking coal and calcium hydroxide according to the mass ratio of 0.02 to 0.2, forming small balls of 3-8mm by a disc pelletizer, drying and solidifying the raw balls on a chain grate by hot air, wherein the material height is 100mm, the inlet temperature is 300 ℃, and the CO is introduced in the drying and solidifying process, and the mass ratio of the raw balls to the vanadium extraction tailings, the coking coal and the calcium hydroxide is 0.02 2 The content is 30 percent and the humidity is 40g/m 3 The airflow speed of the hot airflow is 0.5m/s, and the time is 30min.
(2) And (2) reducing the composite pellets after drying and consolidation in the step (1) for 90min at 1100 ℃ under the condition that 50% of coal is matched inside and outside the rotary kiln to obtain a reduced material.
Example 2
(1) Adding 80% of Mg (HCO) with-325 meshes 3 ) 2 Uniformly mixing the raw materials with vanadium extraction tailings, coking coal and calcium hydroxide according to the mass ratio of 0.02 to 0.2, forming small balls of 3-8mm by a disc pelletizer, drying and solidifying the raw balls on a chain grate by hot air, wherein the material height is 100mm, the inlet temperature is 300 ℃, and the CO is introduced in the drying and solidifying process, and the mass ratio of the raw balls to the vanadium extraction tailings, the coking coal and the calcium hydroxide is 0.02 2 The content is 30 percent and the humidity is 40g/m 3 The airflow speed of the hot airflow is 0.5m/s, and the time is 30min.
(2) And (3) reducing the composite pellets after drying and consolidation in the step (1) for 90min at 1100 ℃ under the condition that 50% of coal is mixed inside and outside the rotary kiln to obtain a reduced material.
Example 3
(1) Adding 80% of Ca (HCO) with-325 meshes 3 ) 2 -FeCO 3 The raw materials are uniformly mixed with the vanadium extraction tailings, the coking coal and the calcium hydroxide according to the mass ratio of 0.2 2 The content is 30 percent and the humidity is 40g/m 3 The airflow speed of the hot airflow is 0.5m/s, and the time is 30min.
(2) And (3) reducing the composite pellets after drying and consolidation in the step (1) for 90min at 1100 ℃ under the condition that 50% of coal is mixed inside and outside the rotary kiln to obtain a reduced material.
Example 4
(1) Adding 80% of Mg (HCO) with-325 meshes 3 ) 2 -FeCO 3 (the mass ratio is 1) 2 The content is 30 percent and the humidity is 40g/m 3 The airflow speed of the hot airflow is 0.5m/s, and the time is 30min.
(2) And (3) reducing the composite pellets after drying and consolidation in the step (1) for 90min at 1100 ℃ under the condition that 50% of coal is mixed inside and outside the rotary kiln to obtain a reduced material.
Example 5
(1) More than or equal to 80 percent of Ca (HCO) with a mesh of-325 3 ) 2 -Mg(HCO 3 ) 2 (the mass ratio is 1) 2 The content is 30 percent and the humidity is 40g/m 3 Of (2)The air flow rate is 0.5m/s, and the time is 30min.
(2) And (3) reducing the composite pellets after drying and consolidation in the step (1) for 90min at 1100 ℃ under the condition that 50% of coal is mixed inside and outside the rotary kiln to obtain a reduced material.
Example 6
(1) Adding 80% of Ca (HCO) with-325 meshes 3 ) 2 -FeCO 3 -Mg(HCO 3 ) 2 The raw materials are uniformly mixed with the vanadium extraction tailings, the coking coal and the calcium hydroxide according to a mass ratio of 0.02 to 0.1, a pellet with the diameter of 3-8mm is formed by a disk pelletizer, the raw pellets are dried and consolidated on a chain grate by hot air, the material height is 100mm, and the temperature is 300 ℃ and the CO content is 100mm in the drying and consolidation process 2 The content is 30 percent and the humidity is 40g/m 3 The airflow speed of the hot airflow is 0.5m/s, and the time is 30min.
(2) And (3) reducing the composite pellets after drying and consolidation in the step (1) for 90min at 1100 ℃ under the condition that 50% of coal is mixed inside and outside the rotary kiln to obtain a reduced material.
Example 7
Example 1 was repeated except that the dry consolidation mode of step (1) was: and carrying out drying consolidation in a high-frequency electromagnetic field drying consolidation mode. The process conditions of drying and consolidation are as follows:
introducing CO at 300 ℃ in the drying and consolidation process 2 The content is 30 percent and the humidity is 40g/m 3 The airflow speed of the hot airflow is 0.5m/s; the drying and solidifying temperature of the high-frequency electromagnetic field is 350 ℃, the drying and solidifying time is 30min, and the power density of the high-frequency electromagnetic field is 25kw/m 3 。
Example 8
Example 2 was repeated except that the drying consolidation mode of step (1) was: and drying and consolidating in a high-frequency electromagnetic field drying and consolidating mode. The process conditions of drying and consolidation are as follows:
introducing CO at 300 deg.C during drying and consolidation 2 The content is 30 percent and the humidity is 40g/m 3 The airflow speed of the hot airflow is 0.5m/s; the drying and solidifying temperature of the high-frequency electromagnetic field is 350 ℃, the drying and solidifying time is 30min, and the power density of the high-frequency electromagnetic field is 25kw/m 3 。
Example 9
Example 3 was repeated except that the dry consolidation mode of step (1) was: and carrying out drying consolidation in a high-frequency electromagnetic field drying consolidation mode. The process conditions of drying and consolidation are as follows:
introducing CO at 300 deg.C during drying and consolidation 2 The content is 30 percent and the humidity is 40g/m 3 The airflow speed of the hot airflow is 0.5m/s; the drying and solidifying temperature of the high-frequency electromagnetic field is 350 ℃, the drying and solidifying time is 30min, and the power density of the high-frequency electromagnetic field is 25kw/m 3 。
Example 10
Example 4 was repeated except that the dry consolidation mode of step (1) was: and drying and consolidating in a high-frequency electromagnetic field drying and consolidating mode. The process conditions of drying and consolidation are as follows:
introducing CO at 300 deg.C during drying and consolidation 2 The content is 30 percent and the humidity is 40g/m 3 The airflow speed of the hot airflow is 0.5m/s; the drying and solidifying temperature of the high-frequency electromagnetic field is 350 ℃, the drying and solidifying time is 30min, and the power density of the high-frequency electromagnetic field is 25kw/m 3 。
Example 11
Example 5 was repeated except that the dry consolidation mode of step (1) was: and carrying out drying consolidation in a high-frequency electromagnetic field drying consolidation mode. The process conditions of drying and consolidation are as follows:
introducing CO at 300 deg.C during drying and consolidation 2 The content is 30 percent and the humidity is 40g/m 3 The airflow speed of the hot airflow is 0.5m/s; the drying and solidifying temperature of the high-frequency electromagnetic field is 350 ℃, the drying and solidifying time is 30min, and the power density of the high-frequency electromagnetic field is 25kw/m 3 。
Example 12
Example 6 was repeated except that the dry consolidation mode of step (1) was: and drying and consolidating in a high-frequency electromagnetic field drying and consolidating mode. The process conditions of drying and consolidation are as follows:
introducing CO at 300 ℃ in the drying and consolidation process 2 The content is 30 percent and the humidity is 40g/m 3 The airflow speed of the hot airflow is 0.5m/s; the drying and solidifying temperature of the high-frequency electromagnetic field is 350 ℃, the drying and solidifying time is 30min, and the power density of the high-frequency electromagnetic field is 25kw/m 3 。
Example 13
Example 1 was repeated except that the dry consolidation mode of step (1) was: drying and solidifying are carried out in a hot air pre-drying and solidifying mode and a high-frequency electromagnetic field drying and solidifying mode. The process conditions of drying and consolidation are as follows:
the temperature of hot air drying is 200 ℃, the time is 15min, and the moisture of the pellets after hot air drying is 4%. The drying temperature of the high-frequency electromagnetic field is 350 ℃, the drying time is 20min, and the power density of the high-frequency electromagnetic field is 25kw/m 3 。
Example 14
Example 2 was repeated except that the drying consolidation mode of step (1) was: drying and solidifying are carried out in a hot air pre-drying and solidifying mode and a high-frequency electromagnetic field drying and solidifying mode. The process conditions of drying and consolidation are as follows:
the temperature of hot air drying is 200 ℃, the time is 15min, and the moisture of the pellets after hot air drying is 4%. The drying temperature of the high-frequency electromagnetic field is 350 ℃, the drying time is 20min, and the power density of the high-frequency electromagnetic field is 25kw/m 3 。
Example 15
Example 3 was repeated except that the dry consolidation mode of step (1) was: drying and solidifying are carried out in a hot air pre-drying and solidifying mode and a high-frequency electromagnetic field drying and solidifying mode. The process conditions of drying and consolidation are as follows:
the temperature of hot air drying is 200 ℃, the time is 15min, and the moisture of the pellets after hot air drying is 4%. The drying temperature of the high-frequency electromagnetic field is 350 ℃, the drying time is 20min, and the power density of the high-frequency electromagnetic field is 25kw/m 3 。
Example 16
Example 4 was repeated except that the dry consolidation mode of step (1) was: drying and solidifying are carried out in a hot air pre-drying and solidifying mode and a high-frequency electromagnetic field drying and solidifying mode. The process conditions of drying and consolidation are as follows:
the temperature of hot air drying is 200 ℃, the time is 15min, and the moisture of the pellets after hot air drying is 4%. The drying temperature of the high-frequency electromagnetic field is 350 ℃, the drying time is 20min, and the power density of the high-frequency electromagnetic field is 25kw/m 3 。
Example 17
Example 5 was repeated except that the dry consolidation mode of step (1) was: drying and solidifying are carried out in a hot air pre-drying and solidifying mode and a high-frequency electromagnetic field drying and solidifying mode. The process conditions of drying and consolidation are as follows:
the temperature of hot air drying is 200 ℃, the time is 15min, and the moisture of the pellets after hot air drying is 4%. The drying temperature of the high-frequency electromagnetic field is 350 ℃, the drying time is 20min, and the power density of the high-frequency electromagnetic field is 25kw/m 3 。
Example 18
Example 6 was repeated except that the dry consolidation mode of step (1) was: drying and solidifying are carried out in a hot air pre-drying and solidifying mode and a high-frequency electromagnetic field drying and solidifying mode. The process conditions of drying and consolidation are as follows:
the temperature of hot air drying is 200 ℃, the time is 15min, and the moisture of the pellets after hot air drying is 4%. The drying temperature of the high-frequency electromagnetic field is 350 ℃, the drying time is 20min, and the power density of the high-frequency electromagnetic field is 25kw/m 3 。
Example 19
Example 13 was repeated except that 10% by mass of iron amphibole (Fe) was added to the raw material of step (1) in the mass ratio of the vanadium extraction tailings 7 Si 8 O 22 (OH) 2 Content 90%).
Example 20
Example 13 was repeated except that hydrated iron oxide (Fe) in an amount of 10% by mass based on the vanadium extraction tailings was further added to the raw material of step (1) 2 O 3 ·nH 2 O content 90%, water content 15%).
Example 21
Example 13 was repeated except that 10% by mass of Diels (Fe) based on the vanadium extraction tailings was further added to the raw material of step (1) 18 Si 12 O 40 (OH) 10 Content 90%).
Example 22
Example 13 was repeated except that tremolite (2 CaO 5MgO 8 SiO) in an amount of 10% by mass based on the vanadium extraction tailings was further added to the raw material of step (1) 2 ·H 2 O content 90%).
Comparative example 1
(1) Uniformly mixing the vanadium extraction tailings, the coking coal and the calcium hydroxide according to the mass ratio of 1.15Drying and solidifying the pellets and the green pellets on a high-frequency electromagnetic field drying and solidifying machine, wherein the material height is 100mm, and CO is introduced at the temperature of 300 ℃ in the drying and solidifying process 2 The content is 30 percent and the humidity is 40g/m 3 The airflow speed of the hot airflow is 0.5m/s, and the time is 30min.
(2) And (3) carrying out reduction treatment on the dried and consolidated composite pellets in the step (1) in a rotary kiln, and reducing for 90min at 1100 ℃ to obtain a reduced material.
Reference document 2
(1) Uniformly mixing the vanadium extraction tailings, the coking coal and the calcium hydroxide according to the mass ratio of 1.15 to 0.02, forming small balls with the diameter of 3-8mm by a disc pelletizer, drying and solidifying the green balls on a high-frequency electromagnetic field drying and solidifying machine, wherein the material height is 100mm, and the introduction temperature is 300 ℃ and the CO content is 100 ℃ in the drying and solidifying process 2 The content is 30 percent and the humidity is 40g/m 3 The airflow speed of the hot airflow is 0.5m/s; the drying and solidifying temperature of the high-frequency electromagnetic field is 350 ℃, the drying and solidifying time is 30min, and the power density of the high-frequency electromagnetic field is 25kw/m 3 。
(2) And (3) carrying out reduction treatment on the dried and consolidated composite pellets in the step (1) in a rotary kiln, and reducing for 90min at 1100 ℃ to obtain a reduced material.
The vanadium extraction tailings adopted by the method are tailings obtained after sodium-modified vanadium extraction of the same batch, the amphiboles are mineral raw materials of the same batch, the hydrated iron oxides are mineral raw materials of the same batch, the dill is mineral raw materials of the same batch, and the tremolites are mineral raw materials of the same batch. The coking coal is the same batch of raw material. The calcium hydroxide is obtained by digesting the same batch of quicklime through the same process. The mixing equipment, the disc pelletizer, the drying system of the chain grate, the high-frequency electromagnetic field drying and solidifying machine and the rotary kiln are the same equipment, the experiment and the effect verification are carried out, and the result is as follows:
it should be noted that, the inventor of the present application performed experiments using copper slag, steel slag, and zinc-containing dust as iron-containing raw materials, and obtained similar experimental results to those described above, which are not described herein again.
In the invention, the compressive strength of the composite pellet is detected according to the GB/T14201-93 standard. The falling strength of the composite pellets is detected according to the GB/T14201-93 standard.
In the present invention, the sodium removal rate is: (1-sodium content in composite pellet/sodium content in whole raw material) 100%; wherein: the whole raw materials comprise iron-containing raw materials, fuel, adhesive and auxiliary agents (C-H-O low-temperature release agent and H-O high-temperature gas slow release agent); the detection of the sodium content can be obtained by an analytical detector in the prior art.
The metallization rate of iron in the reduction material is as follows: in the whole reducing material (slag phase), the elementary substance iron accounts for the weight percentage of the total of the whole iron element components.
Claims (17)
1. A low temperature consolidated composite pellet, the composite pellet comprising: iron-containing raw materials, fuel, a binder and a C-H-O low-temperature releasing agent.
2. The composite pellet of claim 1, wherein: the composite pellet also comprises a H-O high-temperature gas slow release agent.
3. The composite pellet of claim 1, wherein: the C-H-O low-temperature releasing agent is bicarbonate, or the C-H-O low-temperature releasing agent is a mixture of bicarbonate and carbonate;
preferably, the C-H-O low-temperature releasing agent is Ca (HCO) 3 ) 2 、Mg(HCO 3 ) 2 、Ca(HCO 3 ) 2 -FeCO 3 、Mg(HCO 3 ) 2 -FeCO 3 、Ca(HCO 3 ) 2 -Mg(HCO 3 ) 2 Or Ca (HCO) 3 ) 2 -FeCO 3 -Mg(HCO 3 ) 2 。
4. The composite pellet of claim 2, wherein: the H-O high-temperature gas slow release agent is one or more of amphibole, hydrated ferric oxide, dill and tremolite;
preferably, the H-O high-temperature gas slow release agent is Fe 7 Si 8 O 22 (OH) 2 、Fe 2 O 3 ·nH 2 O、Fe 18 Si 12 O 40 (OH) 10 、2CaO·5MgO·8SiO 2 ·H 2 One or more of O.
5. The composite pellet of any one of claims 1-4, wherein: the weight ratio of the iron-containing raw material, the fuel, the binder and the C-H-O low-temperature releasing agent in the composite pellet is (100).
6. The composite pellet of claim 2, wherein: the weight ratio of the addition amount of the H-O high-temperature gas slow-release agent to the iron-containing raw material is 0.1-50, preferably 5-40.
7. The composite pellet of any one of claims 1-6, wherein: the iron-containing raw material is slag and/or metallurgical dust;
preferably, the iron-containing raw material is one or more of vanadium extraction tailings, copper slag, steel slag and zinc-containing dust.
8. The composite pellet of any one of claims 2-7, wherein: the granularity of the C-H-O low-temperature releasing agent is-200 meshes or more than 50 percent, preferably-325 meshes or more than 80 percent; and/or
The granularity of the H-O high-temperature gas slow-release agent is-200 meshes more than or equal to 50 percent, and more preferably-325 meshes more than or equal to 80 percent.
9. The composite pellet of any one of claims 1-8, wherein: the binder is calcium hydroxide; and/or
The fuel is a carbonaceous solid fuel.
10. The composite pellet of any one of claims 1-9, wherein: the particle size of the composite pellet is 1-20mm, preferably 2-10mm, and more preferably 3-8mm.
11. A method of making the composite pellet of any one of claims 1-10, comprising the steps of:
(1) Uniformly mixing the C-H-O low-temperature release agent and the high-temperature gas slow release agent to obtain a mixture I;
(2) Uniformly mixing an iron-containing raw material, a fuel and a binder to obtain a mixture II;
(3) And mixing the mixture I and the mixture II, adding water, stirring and mixing uniformly, and pelletizing to obtain the composite pellet.
12. The method of claim 11, wherein: the adding amount of the water is 3-20 percent of the total weight of the composite pellet, and preferably 5-15 percent;
preferably, atomized water is used as the water added in step (3).
13. The method for dry consolidation of composite pellets according to any of claims 1-10, wherein: and (3) drying and consolidating the composite pellets by adopting an electromagnetic field, or adopting hot air pre-drying and electromagnetic field drying and consolidating.
14. The dry consolidation method according to claim 13, wherein: in the drying and solidifying procedure, CO is introduced 2 And water vapor;
preferably, the CO-containing component 2 The gas mixed with water vapor is addedAdding water vapor and CO 2 Hot air after combustion, blast furnace gas/coke oven gas/converter gas, direct reduction hot tail gas, lime kiln hot tail gas, etc.
15. The dry consolidation method according to claim 14, characterized in that: said CO-containing 2 And water vapor, CO 2 1 to 50%, preferably 5 to 40%, more preferably 10 to 30%; containing CO 2 The humidity of the gas with water vapor is 10g/m 3 ～100g/m 3 Preferably 15g/m 3 ～80g/m 3 More preferably 20g/m 3 ～50g/m 3 。
16. The dry consolidation method according to claim 15, wherein: when the composite pellet is dried and consolidated by adopting an electromagnetic field: the temperature of electromagnetic field drying is 100-500 ℃, preferably 300-400 ℃; the drying and consolidation time is 10min to 60min, preferably 20min to 40min; the power density of the electromagnetic field is 5kw/m 3 ～50kw/m 3 Preferably 20kw/m 3 ～30kw/m 3 。
17. The dry consolidation method according to claim 13, characterized in that: when the composite pellets are dried and consolidated by adopting hot air pre-drying and electromagnetic field drying:
the temperature of the hot air is 100-500 ℃, and preferably 200-400 ℃; the hot air pre-drying time is 10min to 60min, preferably 10min to 20min; the water content in the composite pellets after hot air pre-drying is 2-8%, preferably 3-6%;
the drying temperature of the electromagnetic field is 100-500 ℃, and the preferred temperature is 300-400 ℃; the drying and solidifying time is 5min to 40min, preferably 10min to 30min; the power density of the electromagnetic field is 5kw/m 3 ～50kw/m 3 Preferably 20kw/m 3 ～30kw/m 3 。
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