CN113735467A - Modified steel slag and preparation method and application thereof - Google Patents
Modified steel slag and preparation method and application thereof Download PDFInfo
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- CN113735467A CN113735467A CN202110928162.1A CN202110928162A CN113735467A CN 113735467 A CN113735467 A CN 113735467A CN 202110928162 A CN202110928162 A CN 202110928162A CN 113735467 A CN113735467 A CN 113735467A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 227
- 239000002893 slag Substances 0.000 title claims abstract description 227
- 239000010959 steel Substances 0.000 title claims abstract description 227
- 238000002360 preparation method Methods 0.000 title claims abstract description 20
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 117
- 229910052742 iron Inorganic materials 0.000 claims abstract description 51
- 238000000498 ball milling Methods 0.000 claims abstract description 41
- 239000003245 coal Substances 0.000 claims abstract description 41
- 239000002131 composite material Substances 0.000 claims abstract description 40
- 239000003607 modifier Substances 0.000 claims abstract description 38
- 239000013049 sediment Substances 0.000 claims abstract description 38
- 238000005245 sintering Methods 0.000 claims abstract description 18
- 230000004048 modification Effects 0.000 claims abstract description 17
- 238000012986 modification Methods 0.000 claims abstract description 17
- 238000000034 method Methods 0.000 claims abstract description 15
- 238000010791 quenching Methods 0.000 claims abstract description 12
- 230000000171 quenching effect Effects 0.000 claims abstract description 12
- 238000002156 mixing Methods 0.000 claims abstract description 11
- 239000002245 particle Substances 0.000 claims description 50
- 239000004568 cement Substances 0.000 claims description 31
- 239000000843 powder Substances 0.000 claims description 26
- 238000001035 drying Methods 0.000 claims description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 20
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 18
- 229910052593 corundum Inorganic materials 0.000 claims description 18
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 claims description 18
- 239000000203 mixture Substances 0.000 claims description 18
- 229910001845 yogo sapphire Inorganic materials 0.000 claims description 18
- 238000007885 magnetic separation Methods 0.000 claims description 13
- 239000004567 concrete Substances 0.000 claims description 12
- 239000000463 material Substances 0.000 claims description 12
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- 230000003203 everyday effect Effects 0.000 claims description 5
- 238000007873 sieving Methods 0.000 claims description 5
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N titanium dioxide Inorganic materials O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 5
- 238000000265 homogenisation Methods 0.000 claims description 2
- 238000011085 pressure filtration Methods 0.000 claims description 2
- 230000000694 effects Effects 0.000 abstract description 23
- 239000002699 waste material Substances 0.000 abstract description 9
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- 238000012360 testing method Methods 0.000 description 25
- 239000012071 phase Substances 0.000 description 23
- 239000000292 calcium oxide Substances 0.000 description 17
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 17
- 239000013078 crystal Substances 0.000 description 16
- 229910052500 inorganic mineral Inorganic materials 0.000 description 15
- 239000011707 mineral Substances 0.000 description 15
- 239000004570 mortar (masonry) Substances 0.000 description 14
- 238000001878 scanning electron micrograph Methods 0.000 description 13
- 239000011575 calcium Substances 0.000 description 9
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 9
- KKCBUQHMOMHUOY-UHFFFAOYSA-N Na2O Inorganic materials [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 7
- 238000003756 stirring Methods 0.000 description 7
- 238000002441 X-ray diffraction Methods 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
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- 239000007791 liquid phase Substances 0.000 description 4
- 239000013618 particulate matter Substances 0.000 description 4
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 239000011083 cement mortar Substances 0.000 description 3
- 229910052681 coesite Inorganic materials 0.000 description 3
- 229910052906 cristobalite Inorganic materials 0.000 description 3
- 238000001879 gelation Methods 0.000 description 3
- 238000006703 hydration reaction Methods 0.000 description 3
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 3
- 238000003825 pressing Methods 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- 239000002910 solid waste Substances 0.000 description 3
- 229910052682 stishovite Inorganic materials 0.000 description 3
- 229910052905 tridymite Inorganic materials 0.000 description 3
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- NWXHSRDXUJENGJ-UHFFFAOYSA-N calcium;magnesium;dioxido(oxo)silane Chemical compound [Mg+2].[Ca+2].[O-][Si]([O-])=O.[O-][Si]([O-])=O NWXHSRDXUJENGJ-UHFFFAOYSA-N 0.000 description 2
- 239000012141 concentrate Substances 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000018109 developmental process Effects 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 229960001484 edetic acid Drugs 0.000 description 2
- 229910001385 heavy metal Inorganic materials 0.000 description 2
- 230000036571 hydration Effects 0.000 description 2
- NUJOXMJBOLGQSY-UHFFFAOYSA-N manganese dioxide Chemical compound O=[Mn]=O NUJOXMJBOLGQSY-UHFFFAOYSA-N 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 239000004576 sand Substances 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- 229910001341 Crude steel Inorganic materials 0.000 description 1
- 235000019738 Limestone Nutrition 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- ULGYAEQHFNJYML-UHFFFAOYSA-N [AlH3].[Ca] Chemical compound [AlH3].[Ca] ULGYAEQHFNJYML-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000011384 asphalt concrete Substances 0.000 description 1
- DDEHZCWFAUZBEH-UHFFFAOYSA-O azanium;ethanol;nitrate Chemical compound [NH4+].CCO.[O-][N+]([O-])=O DDEHZCWFAUZBEH-UHFFFAOYSA-O 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- 239000000378 calcium silicate Substances 0.000 description 1
- 229910052918 calcium silicate Inorganic materials 0.000 description 1
- PASHVRUKOFIRIK-UHFFFAOYSA-L calcium sulfate dihydrate Chemical compound O.O.[Ca+2].[O-]S([O-])(=O)=O PASHVRUKOFIRIK-UHFFFAOYSA-L 0.000 description 1
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 1
- WETINTNJFLGREW-UHFFFAOYSA-N calcium;iron;tetrahydrate Chemical compound O.O.O.O.[Ca].[Fe].[Fe] WETINTNJFLGREW-UHFFFAOYSA-N 0.000 description 1
- XFWJKVMFIVXPKK-UHFFFAOYSA-N calcium;oxido(oxo)alumane Chemical compound [Ca+2].[O-][Al]=O.[O-][Al]=O XFWJKVMFIVXPKK-UHFFFAOYSA-N 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000009614 chemical analysis method Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000010668 complexation reaction Methods 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 229910052637 diopside Inorganic materials 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000010459 dolomite Substances 0.000 description 1
- 229910000514 dolomite Inorganic materials 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 239000010433 feldspar Substances 0.000 description 1
- 239000003337 fertilizer Substances 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 231100001261 hazardous Toxicity 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical compound [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- 229910052609 olivine Inorganic materials 0.000 description 1
- 239000010450 olivine Substances 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 239000011029 spinel Substances 0.000 description 1
- -1 tailings Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B5/00—Treatment of metallurgical slag ; Artificial stone from molten metallurgical slag
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B5/00—Treatment of metallurgical slag ; Artificial stone from molten metallurgical slag
- C04B5/06—Ingredients, other than water, added to the molten slag or to the granulating medium or before remelting; Treatment with gases or gas generating compounds, e.g. to obtain porous slag
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
The invention provides a modified steel slag and a preparation method and application thereof. The modified steel slag consists of steel slag and a composite modifier, wherein the composite modifier consists of reservoir sediment, coal gangue and iron tailings; the mass ratio of the steel slag to the composite modifier is as follows: 70-80: 20-30; the mass ratio of the iron tailings, the reservoir sediment and the coal gangue in the composite modifier is as follows: 3-4: 2-3: 1. the preparation method of the modified steel slag comprises the following steps: the method comprises the steps of reservoir sediment pretreatment, coal gangue pretreatment, iron tailing pretreatment, steel slag pretreatment, ball milling and mixing, press forming, sintering modification and blast quenching. According to the invention, the reservoir sediment, the coal gangue and the iron tailings are used as the composite modifier to modify the steel slag, so that the valuable components in the steel slag are effectively utilized, and the gelling activity and stability of the steel slag are improved. The preparation method is easy to implement, the process flow is simple, the large-scale utilization of the waste is realized, and the purposes of environmental protection, energy conservation and resource utilization are achieved.
Description
Technical Field
The invention belongs to the technical field of comprehensive utilization of resources, and particularly relates to modified steel slag and a preparation method and application thereof.
Background
The steel slag is waste slag in the steel-making industry, mainly comes from smelting fluxes such as limestone, dolomite, iron ore and the like added in the steel making process, slagging materials added for adjusting the properties of steel materials, impurities separated from two liquid-phase furnace charges which are melted at high temperature and do not melt mutually and the like, and the emission amount of the steel slag is about 12-20% of the yield of crude steel. The annual output of steel slag in China is about 0.8 hundred million tons, the accumulated stockpiling is about 5 hundred million tons, and the comprehensive utilization rate is less than 40 percent. The chemical components of the steel slag mainly comprise SiO2、CaO、MgO、Fe2O3Also, a small amount of Al is required2O3、MnO2、P2O5Etc. (see fig. 1), the main mineral composition of which comprises calcium silicate (C)2S，C3S), calcium ferrite (C)4AF、C2F) Calcium aluminate (C)12A7、C3A) RO phase, metallic iron, olivine, magnetite (Fe)3O4) Free calcium oxide (f-CaO), and the like, and the chemical composition and the mineral composition of the steel slag are similar to those of cement. The steel slag can react with water to generate Ca (OH)2C-S-A-H gel, C-A-H crystal, C-S-H gel, etc. At present, the steel slag is mainly applied to roadbed engineering, engineering backfill materials, asphalt concrete aggregates and the like, but the application of the steel slag in cement concrete is less than 10 percent of the total utilization amount of the steel slag, and in recent years, people mainly research the excitation way of the gelation property of the steel slag and prepare new steel slagFeasibility of the material. But the utilization rate of the steel slag is still low, which reflects that the steel slag still has defects in the research of the basic property of the steel slag.
The reservoir is used as a hydraulic engineering building for regulating water flow and resisting flood and drought disasters, the transportation and exchange of material energy between water bodies are changed to a certain extent, and sediment in the water is gradually deposited at the water bottom along with the difference of the landform and the hydrodynamic force of the reservoir. And the sediments can transform a large amount of stored organic matters, heavy metals and other substances into a water body through a biogeochemical process under certain conditions, so that the ecological system of the lake and reservoir is influenced. Because the property of the bottom mud of the reservoir is close to that of the soil, and the contents of organic matters, mineral substances and the like are rich, the water-based organic compound fertilizer has high utilization value, and if the bottom mud is subjected to harmless treatment and then is subjected to resource utilization, the environment can be protected, and resources can be saved.
How to effectively utilize the steel slag and the reservoir bottom mud, changing waste into valuables, greatly reducing the environmental pollution, and simultaneously realizing great economic benefit and social benefit, the technical problem needs to be solved urgently.
Disclosure of Invention
The invention provides a modified steel slag, a preparation method and application thereof, which can effectively utilize the steel slag and reservoir sediment to realize the purposes of energy conservation and environmental protection, and can change waste into valuable, so that the solid waste generates higher economic value, and the green sustainable development of the solid waste is realized.
The invention relates to modified steel slag, which consists of steel slag and a composite modifier, wherein the composite modifier consists of reservoir bottom mud, coal gangue and iron tailings; the steel slag and the composite modifier have the following mass ratio: 70-80: 20-30; the mass ratio of the iron tailings, the reservoir sediment and the coal gangue in the composite modifier is as follows: 3-4: 2-3: 1.
the invention also comprises a preparation method of the modified steel slag, which comprises the following steps:
s1, reservoir sediment pretreatment: standing and dehydrating the reservoir bottom mud to enable the water content of the reservoir bottom mud to be 25-35%, then airing and sieving, drying the product under the sieve, and then performing ball milling and homogenization treatment to obtain the pretreated reservoir bottom mud;
s2, coal gangue pretreatment: crushing the coal gangue into particles with the particle size of 1-2 mm by using a jaw crusher, drying for 12 hours at 105 ℃, and ball-milling to 150-200 meshes to obtain pretreated coal gangue;
s3, iron tailing pretreatment: drying the iron tailings at 105 ℃ for 12 hours, and then ball-milling the iron tailings to 150-200 meshes to obtain pretreated iron tailings;
s4, steel slag pretreatment: crushing the steel slag into particles with the particle size of 1-2 mm by using a jaw crusher, drying the particles for 12 hours at 105 ℃, and performing ball milling on the particles to 150-200 meshes to obtain pretreated steel slag;
s5, ball milling and mixing: ball-milling and uniformly mixing the pretreated steel slag, iron tailings, coal gangue and reservoir sediment;
s6, press forming: adding water accounting for 2-5% of the mass of the mixture obtained in the step S5, and performing compression molding;
s7, sintering modification: placing the material cake pressed and formed in the step S6 in a muffle furnace, and sintering and modifying;
s8, blast quenching: and (4) carrying out blast quenching on the steel slag subjected to sintering modification in the step (S7) to obtain the modified steel slag.
Optionally, the bottom mud in the reservoir in the step S1 is left to stand and dehydrate for 7 days, stirred for 1 time every day, and subjected to pressure filtration to make the water content of the bottom mud be 25-35%; the ball milling is carried out in a cement ball mill for 5-15 min, and the ball milling speed is 25.4 r/min.
Optionally, the main components and contents of the reservoir sediment in the step S1 are as follows: SiO 2240～60％，Al2O310～30％，Fe2O31～15％，MgO 1～5％，CaO 3～10％，Na2O 0.1～5％，K2O 0.1～5％，P2O50.01～3％，TiO20.01-3% and loss on ignition of 1-20%.
Optionally, the steel slag in step S4 mainly comprises the following components in percentage by weight: SiO 2210～20％，Al2O31～7％，Fe2O32～33％，MgO 3～12％，CaO 30～50％，FeO 3～15％，Na2O 0.01～3％，K2O 0.01～3％，SO30.26％，P2O51～6％。
Optionally, the main components and contents of the coal gangue in the step S2 are: SiO 2220～60％，Al2O310～40％，Fe2O30.1～10％，FeO 0.1～10％，MgO 0.01～6％，CaO 0.01～6％，K2O 0.01～5％，SO20.01-10% and loss on ignition of 5-40%.
Optionally, in the step S6, the pressure of the press forming is 15 to 35 MPa.
Optionally, in step S7, the sintering is modified by: raising the temperature to 1150-1250 ℃ at a speed of 10 ℃/min, and preserving the heat for 25 min.
The invention also comprises the efficient utilization of the modified steel slag, the modified steel slag in the step S8 is ground to 200 meshes by a ball mill, and then is put into a 1-2T strong magnetic separator for magnetic separation to obtain fine iron powder and modified steel slag powder, and the modified steel slag powder is applied to the preparation of cement concrete.
Optionally, the rotating speed of the magnetic separator is 10-20 r/min.
With the development of environmental protection situation, solid wastes such as tailings, steel slag and the like are used as mineral admixtures to prepare cement concrete, but the utilization rate of the steel slag in the cement concrete is low, and the large-scale application of the steel slag in the cement and concrete building material industry is limited due to the problems of unstable volume, poor grindability, poor gelling activity and the like of the steel slag. The steel slag has high forming temperature, large crystal grains, compact crystallization and C in the system3S and C2The content of S is only 50-70% of that of cement clinker, which causes poor gelation, wherein the content of f-CaO and f-MgO containing 5-10% of the S generates 97.8% of volume expansion in hydration reaction, which causes poor volume stability. Aiming at the problems in the application of the steel slag, the invention provides a method for introducing reservoir sediment, coal gangue and iron tailings as cheap composite modifiers based on the idea of treating waste by waste, adjusting the composition and structure of the steel slag, controlling the secondary phase reaction, effectively utilizing the valuable components in the steel slag and improving the gelling activity and stability of the steel slag.
Compared with the prior art, the invention has the following technical effects:
1) according to the invention, the reservoir sediment, the coal gangue and the iron tailings are used as the composite modifier to modify the steel slag, so that the valuable components in the steel slag are effectively utilized, and the gelling activity and stability of the steel slag are improved.
2) The preparation method is easy to implement, the process flow is simple, the large-scale utilization of wastes can be realized, and the aims of environmental protection, energy conservation and resource utilization are finally fulfilled.
Drawings
FIG. 1 is a flow chart of the preparation and application process of the modified steel slag of the invention.
FIG. 2 is an XRD pattern of the steel slag modified at different temperatures.
FIG. 3 is an SEM image of modified steel slag of example 1 with magnification of 3000 times.
FIG. 4 is an SEM image of 6000 times magnification of the modified steel slag of example 1 of the invention.
FIG. 5 is an SEM image of modified steel slag of example 2 with magnification of 3000 times.
FIG. 6 is an SEM image of 6000 times magnification of modified steel slag of example 2 of the present invention.
FIG. 7 is an SEM image of modified steel slag of example 3 of the present invention magnified 3000 times.
FIG. 8 is an SEM image of 6000 times magnification of modified steel slag of example 3 of the present invention.
FIG. 9 is EDS chart of modified steel slag of example 1 of the present invention.
FIG. 10 is EDS chart of modified steel slag of example 2 of the present invention.
FIG. 11 is EDS chart of modified steel slag of example 3 of the present invention.
FIG. 12 is a graph showing the f-Cao and f-MgO contents of the modified steel slag and the original steel slag according to examples 1 to 3 of the present invention.
Fig. 13 is an XRD pattern of the fine iron powder after the high-intensity magnetic separation of the present invention.
FIG. 14 is an SEM image of the iron concentrate powder after the strong magnetic separation according to the present invention.
Fig. 15 is an EDX spectrum of the particulate matter 1 in the SEM picture of the fine iron powder after the strong magnetic separation of the present invention.
Fig. 16 is an EDX spectrum of the particulate matter 2 in the SEM picture of the fine iron powder after the strong magnetic separation according to the present invention.
Detailed Description
The following embodiments are described in detail with reference to the accompanying drawings, so that how to implement the technical features of the present invention to solve the technical problems and achieve the technical effects can be fully understood and implemented.
Example 1
The modified steel slag comprises steel slag and a composite modifier, wherein the composite modifier comprises reservoir bottom mud, coal gangue and iron tailings; the steel slag and the composite modifier have the following mass ratio: 70: 30, of a nitrogen-containing gas; the mass ratio of the iron tailings, the reservoir sediment and the coal gangue in the composite modifier is as follows: 3: 2: 1.
the preparation method of the modified steel slag comprises the following steps:
s1, reservoir sediment pretreatment: standing and dehydrating the reservoir sediment for 7 days, stirring for 1 time every day, and performing filter pressing to ensure that the water content is 35%; drying in the air, sieving, baking fine powder with more than 100 meshes in the air, and then carrying out ball milling to obtain pretreated reservoir sediment; the ball milling is carried out in a cement ball mill for 15min, and the ball milling speed is 25.4 r/min.
S2, coal gangue pretreatment: crushing the coal gangue into particles with the particle size of 1-2 mm by using a jaw crusher, drying the particles for 24 hours at 105 ℃, and performing ball milling on the particles to 150-200 meshes to obtain pretreated coal gangue;
s3, iron tailing pretreatment: crushing the iron tailings into particles with the particle size of 1-2 mm by using a jaw crusher, drying for 12 hours at 105 ℃, and ball-milling to 150-200 meshes to obtain pretreated iron tailings;
s4, steel slag pretreatment: crushing the steel slag into particles with the particle size of 1-2 mm by using a jaw crusher, drying the particles for 12 hours at 105 ℃, and performing ball milling on the particles to 150-200 meshes to obtain pretreated steel slag;
s5, ball milling and mixing: ball-milling and mixing the pretreated steel slag, iron tailings, coal gangue and reservoir sediment;
s6, press forming: adding water accounting for 2% of the mass of the mixture obtained in the step S5 into the mixture, and performing compression molding under the pressure of 35 MPa;
s7, sintering modification: placing the material cake pressed and formed in the step S6 in a muffle furnace, raising the temperature to 1150 ℃ at a speed of 10 ℃/min, preserving the temperature for 25min, and sintering and modifying;
s8, blast quenching: and (4) carrying out blast quenching on the steel slag subjected to sintering modification in the step (S7) to obtain the modified steel slag.
Wherein, the main components and contents of the reservoir sediment in the step S1 are as follows: SiO 2240～60％，Al2O310～30％，Fe2O31～15％％，MgO 1～5％％，CaO 3～10％，Na2O 0.1～5％，K2O 0.1～5％％，P2O50.01～3％％，TiO20.01-3% and loss on ignition of 1-20%.
The steel slag in the step S4 comprises the following main components in percentage by weight: SiO 2210～20％，Al2O31～7％，Fe2O32～33％，MgO 3～12％，CaO 30～50％，FeO 3～15％，Na2O 0.01～3％，K2O 0.01～3％，SO30.26％，P2O51～6％。
The main components and contents of the coal gangue in the step S2 are as follows: SiO 2220～60％，Al2O310～40％％，Fe2O30.1～10％，FeO 0.1～10％，MgO 0.01～6％％，CaO 0.01～6％％，K2O 0.01～5％，SO20.01-10% and 5-40% of loss on ignition.
The application of the modified steel slag comprises the steps of carrying out strong magnetic iron separation on the modified steel slag to obtain fine iron powder and modified steel slag powder, and applying the modified steel slag powder to the preparation of cement concrete. The magnetic field intensity of the strong magnetic separation iron is 1.5T, and the rotating speed of the magnetic separator is 20 r/min.
Example 2
The modified steel slag comprises steel slag and a composite modifier, wherein the composite modifier comprises reservoir bottom mud, coal gangue and iron tailings; the steel slag and the composite modifier have the following mass ratio: 80: 20; the mass ratio of the iron tailings, the reservoir sediment and the coal gangue in the composite modifier is as follows: 4: 3: 1.
the preparation method of the modified steel slag comprises the following steps:
s1, reservoir sediment pretreatment: standing and dehydrating the reservoir sediment for 7 days, stirring for 1 time every day, and performing filter pressing to ensure that the water content is 30%; drying in the air, sieving, baking fine powder with more than 100 meshes in the air, and then carrying out ball milling to obtain pretreated reservoir sediment; the ball milling is carried out in a cement ball mill for 5min, and the ball milling speed is 25.4 r/min.
S2, coal gangue pretreatment: crushing the coal gangue into particles with the particle size of 1-2 mm by using a jaw crusher, drying the particles for 24 hours at 105 ℃, and performing ball milling on the particles to 150-200 meshes to obtain pretreated coal gangue;
s3, iron tailing pretreatment: crushing the iron tailings into particles with the particle size of 1-2 mm by using a jaw crusher, drying for 12 hours at 105 ℃, and ball-milling to 150-200 meshes to obtain pretreated iron tailings;
s4, steel slag pretreatment: crushing the steel slag into particles with the particle size of 1-2 mm by using a jaw crusher, drying the particles for 12 hours at 105 ℃, and performing ball milling on the particles to 150-200 meshes to obtain pretreated steel slag;
s5, ball milling and mixing: ball-milling and mixing the pretreated steel slag, iron tailings, coal gangue and reservoir sediment;
s6, press forming: adding 5% by mass of water into the mixture obtained in the step S5, and performing compression molding under the pressure of 15 MPa;
s7, sintering modification: placing the material cake pressed and formed in the step S6 in a muffle furnace, heating to 1200 ℃ at the speed of 10 ℃/min, preserving the temperature for 25min, and sintering and modifying;
s8, blast quenching: and (4) carrying out blast quenching on the steel slag subjected to sintering modification in the step (S7) to obtain the modified steel slag.
Wherein, the main components and contents of the reservoir sediment in the step S1 are as follows: SiO 2240～60％，Al2O310～30％，Fe2O31～15％％，MgO 1～5％％，CaO 3～10％，Na2O 0.1～5％，K2O 0.1～5％％，P2O50.01～3％％，TiO20.01-3% and loss on ignition of 1-20%.
The steel slag in the step S4 comprises the following main components in percentage by weight: SiO 2210～20％，Al2O31～7％，Fe2O32～33％，MgO 3～12％，CaO 30～50％，FeO 3～15％，Na2O 0.01～3％，K2O 0.01～3％，SO30.26％，P2O51～6％。
The main components and contents of the coal gangue in the step S2 are as follows: SiO 2220～60％，Al2O310～40％％，Fe2O30.1～10％，FeO 0.1～10％，MgO 0.01～6％％，CaO 0.01～6％％，K2O 0.01～5％，SO20.01-10% and 5-40% of loss on ignition.
The application of the modified steel slag comprises the steps of carrying out strong magnetic iron separation on the modified steel slag to obtain fine iron powder and modified steel slag powder, and applying the modified steel slag powder to the preparation of cement concrete. The magnetic field intensity of the strong magnetic separation iron is 2T, and the rotating speed of the magnetic separator is 10 r/min.
Example 3
The modified steel slag comprises steel slag and a composite modifier, wherein the composite modifier comprises reservoir bottom mud, coal gangue and iron tailings; the steel slag and the composite modifier have the following mass ratio: 75: 25; the mass ratio of the iron tailings, the reservoir sediment and the coal gangue in the composite modifier is as follows: 3.5: 2.5: 1.
the preparation method of the modified steel slag comprises the following steps:
s1, reservoir sediment pretreatment: standing and dehydrating the reservoir sediment for 7 days, stirring for 1 time every day, and performing filter pressing to ensure that the water content is 25%; drying in the air, sieving, baking fine powder with more than 100 meshes in the air, and then carrying out ball milling to obtain pretreated reservoir sediment; the ball milling is carried out in a cement ball mill for 10min, and the ball milling speed is 25.4 r/min.
S2, coal gangue pretreatment: crushing the coal gangue into particles with the particle size of 1-2 mm by using a jaw crusher, drying the particles for 24 hours at 105 ℃, and performing ball milling on the particles to 150-200 meshes to obtain pretreated coal gangue;
s3, iron tailing pretreatment: crushing the iron tailings into particles with the particle size of 1-2 mm by using a jaw crusher, drying for 12 hours at 105 ℃, and ball-milling to 150-200 meshes to obtain pretreated iron tailings;
s4, steel slag pretreatment: crushing the steel slag into particles with the particle size of 1-2 mm by using a jaw crusher, drying the particles for 12 hours at 105 ℃, and performing ball milling on the particles to 150-200 meshes to obtain pretreated steel slag;
s5, ball milling and mixing: ball-milling and mixing the pretreated steel slag, iron tailings, coal gangue and reservoir sediment;
s6, press forming: adding water accounting for 3.5% of the mass of the mixture obtained in the step S5 into the mixture, and performing compression molding under the pressure of 25 MPa;
s7, sintering modification: placing the material cake pressed and formed in the step S6 in a muffle furnace, raising the temperature to 1250 ℃ at the speed of 10 ℃/min, preserving the temperature for 25min, and sintering and modifying;
s8, blast quenching: and (4) carrying out blast quenching on the steel slag subjected to sintering modification in the step (S7) to obtain the modified steel slag.
Wherein, the main components and contents of the reservoir sediment in the step S1 are as follows: SiO 2240～60％，Al2O310～30％，Fe2O31～15％％，MgO 1～5％％，CaO 3～10％，Na2O 0.1～5％，K2O 0.1～5％％，P2O50.01～3％％，TiO20.01-3% and loss on ignition of 1-20%.
The steel slag in the step S4 comprises the following main components in percentage by weight: SiO 2210～20％，Al2O31～7％，Fe2O32～33％，MgO 3～12％，CaO 30～50％，FeO 3～15％，Na2O 0.01～3％，K2O 0.01～3％，SO30.26％，P2O51～6％。
The main components and contents of the coal gangue in the step S2 are as follows: SiO 2220～60％，Al2O310～40％％，Fe2O30.1～10％，FeO 0.1～10％，MgO 0.01～6％％，CaO 0.01～6％％，K2O 0.01～5％，SO20.01-10% and 5-40% of loss on ignition.
The application of the modified steel slag comprises the steps of carrying out strong magnetic iron separation on the modified steel slag to obtain fine iron powder and modified steel slag powder, and applying the modified steel slag powder to the preparation of cement concrete. The magnetic field intensity of the strong magnetic separation iron is 1.8T, and the rotating speed of the magnetic separator is 15 r/min.
Experimental analysis:
and (5) testing the stability. The f-CaO is tested by using ethylene glycol as an extracting agent and an EDTA (ethylene diamine tetraacetic acid) complexation titration method according to YB/T140-2009 steel slag chemical analysis method; f-MgO was measured using ammonium nitrate-ethanol as the extractant.
And (5) testing heavy metals. According to the GB 5085.3-2007 Standard "identification Standard of hazardous waste-identification of leaching toxicity", referring to the requirement of HJ 557-.
And (3) performing mortar test on the steel slag. The gelling activity of the steel slag and the hydration hardening performance of the composite cementing material are mainly researched. The mortar test block is prepared according to GB/T17671-1999 cement mortar Strength test method (ISO method); the composite gelled material of the mortar test block is prepared by grinding fine steel slag powder (410 m) by using a standard test mould of 40mm multiplied by 160mm2Per kg) and phosphogypsum (350 m)2Per kg) as per 9: 1, the water cement ratio (W/C) is 0.5, and the rubber-sand ratio is 1: 3. Stirring with cement mortar stirrer, firstly stirring at low speed for 30s, adding 1350g of standard sand (the mortar ratio is 1: 3), stirring at high speed for 30s when the stirrer is stirred to 60s, standing for 90s, and finally stirring at high speed for 60 s. Pouring the stirred mortar into a standard test mold of 40mm multiplied by 160mm, placing the test mold on a vibrating table for vibration molding, then placing the test mold under standard conditions (the temperature is 20 ℃ plus or minus 1 ℃, and the relative humidity is not lower than 90%) for curing for 24h, then removing the test mold, placing the test block after mold removal into BWJ-III type cement automatic curing (the temperature is 20 ℃ plus or minus 1 ℃), and curing to the age to measure the mortar strength.
The activity index of the steel slag. The activity index of the modified steel slag is determined according to GB/T20491-2006 Steel slag powder for cement and concrete. The formula is a specific calculation mode:
in the formula, A represents the activity index (%) of the steel slag powder;
Rtthe strength of the steel slag sample mortar in corresponding age is in megapascals (MPa);
R0and comparing the strength of the pure cement sample mortar in the corresponding age, wherein the unit is megapascal (MPa).
The modified steel slags prepared in examples 1 to 3 were named as T1, T2 and T3, respectively, and the composition and structure of the modified steel slags were analyzed by XRD and SEM.
Phase composition of modified steel slag
FIG. 2 is an XRD pattern of the steel slag modified at different temperatures. As can be seen from FIG. 2, the mineral phase of the high temperature modified steel slag is greatly changed compared to the original steel slag. The mineral composition of the raw steel slag comprises RO phase and C3S、C2S、C2F、f-CaO、C12A7、Ca2Al2Si3O12MgO, and C3S and C2The diffraction peak of the S-gelling mineral is weak, and the spectrum peak is broadened. After the steel slag is treated at high temperature by introducing the composite modifier, the mineral composition of the modified steel slag is obviously changed, the diffraction peaks of f-CaO, MgO and RO phases are weakened, and C cannot be observed12A7、Ca2Al2Si3O12Shows a diffraction peak of diopside (CMS)2) MgFe spinel2O4) Calcium-aluminium yellow feldspar (C)2AS)、C3A. Magnetite (Fe)3O4) In which C is3A and C2AS is the gel phase. C3S and C2The diffraction peak of S tends to be sharp, and the diffraction intensity is obviously improved. Adopts a blast quenching mode to effectively inhibit C3Decomposition of S during temperature reduction. The diffraction peak of the RO phase was reduced and the diffraction peak intensity of the RO phase of the T1 sample at 1150 ℃ was lower than that of T2 and T3 because the solid solution of the RO phase separated under the high temperature condition, thermo-chemical reaction occurred with the minerals in the composite modifier, FeO in the RO phase was converted into magnetite (Fe)3O4)。CMS2、C2AS、C3A、MgFe2O4The generation of mineral phase, mainly the incorporation of composite modifier and the aluminium-containing component (C) in the steel slag12A7、Ca2Al2Si3O12) The Ca/Si ratio in the system is reduced by the decomposition, and the liquid phase quantity of the system is increased under the action of high temperature, thereby being beneficial to the diffusion and the crystal generation and promoting the generation of new mineral phases. Comparing the curves T1, T2 and T3, it can be seen that the influence of temperature on the mineral composition of the steel slag is very significant. MgFe with increasing temperature2O4The diffraction peak of (a) was gradually sharp, indicating that high temperature can promote the formation of this species. MgFe in T3 compared to T12O4The diffraction peak of (2) is reduced, probably because after decomposition of the RO phase, the temperature is increased continuously while MgFe in the system is present2O4Decomposition occurs and RO phase is reformed, so that too high temperature may adversely affect the gelation properties of the modified steel slag. The analysis result shows that C in the high-temperature modified steel slag of the invention3S and C2The S content is obviously improved, and a new gel phase C is generated3A and C2AS, and can well eliminate the influence of f-CaO on the poor volume stability of the steel slag, and the content of RO phase is reduced, thereby being capable of showing the grindability of the steel slag. According to the XRD analysis result of the modified steel slag mineral composition, the following chemical reactions mainly occur in the high-temperature modification process of the steel slag:
2CaO+SiO2＝C2S
CaO+C2S＝C3S
CaO+Fe2O3＝C2F
3CaO+Al2O3＝C3A
MgO+Fe2O3＝MgFe2O4
2CaO+Al2O3+SiO2＝C2AS
CaO+MgO+2SiO2＝CMS2
microstructure of modified steel slag
FIG. 3 is an SEM image of modified steel slag of example 1 with magnification of 3000 times; FIG. 3 is an SEM image of 6000 times magnification of modified steel slag of example 1 of the present invention; FIG. 4 is an SEM image of modified steel slag of example 2 with magnification of 3000 times; FIG. 5 is an SEM image of 6000 times magnification of modified steel slag of example 2 of the present invention; FIG. 6 is an SEM image of modified steel slag of example 3 of the present invention magnified 3000 times; FIG. 7 is an SEM image of 6000 times magnification of modified steel slag of example 3 of the present invention. It can be seen from fig. 3 and 4 that the crystal shape of the modified steel slag is not obvious, the modified steel slag is distributed in a lump shape as a whole, no obvious boundary exists between crystals, the size is small, a small amount of regular tetrahedral structure exists, and the crystals are partially spherical. The crystals in fig. 5 and 6 are relatively uniformly and densely distributed, distinct boundaries exist between crystals, the crystal surface is rough, no distinct shape exists, and no regular tetrahedral structure exists. Fig. 7 and 8 show the micro-morphology of the modified steel slag at 1250 ℃, and it can be seen that the crystal structure is more irregular, the original regular tetrahedron structure is damaged and becomes incomplete, it is possible that the mineral of the modified steel slag is decomposed at high temperature, a small amount of spherical crystals and irregularly collided crystals exist on the regular tetrahedron, no boundary is crossed between the crystals to grow, and the needle-rod-shaped substances are inserted among the crystal structures.
FIG. 9 is EDS chart of modified steel slag of example 1 of the present invention; FIG. 10 is EDS chart of modified steel slag of example 2 of the present invention; FIG. 11 is EDS chart of modified steel slag of example 3 of the present invention. As can be seen from FIGS. 9-11 in conjunction with FIGS. 2-8, there is no distinct boundary between the particles in the modified steel slag, and the Ca/Si ratio of the particles shown by point 1 in FIG. 3 is close to C3And S. Points 2 and C in FIG. 62F has similar proportion, wherein Mn oxide is dissolved in the solution and distributed in C3Around S. The ratio of point 3 in FIG. 8 is close to MgFe2O4. C produced at 1150 ℃ by steel slag doped with composite modifier3The amount of S is large, and MgO decomposed from the RO phase is gradually converted into MgFe along with the increase of the temperature2O4. Analyzing the reason, the Ca/Si in the system is improved due to the doping of the reservoir sediment, the liquid phase quantity is increased under the action of high temperature, the diffusion and the crystal production are facilitated, and the C is promoted3S is generated, and simultaneously MgFe is generated by the reaction of MgO and iron oxide2O4Reaction conditions are provided.
Fig. 13 is an XRD pattern of the fine iron powder after the strong magnetic separation of the present invention, fig. 14 is an SEM pattern of the fine iron powder after the strong magnetic separation of the present invention, fig. 15 is an EDX spectrum of the particulate matter 1 in the SEM pattern of the fine iron powder after the strong magnetic separation of the present invention, and fig. 16 is an EDX spectrum of the particulate matter 2 in the SEM pattern of the fine iron powder after the strong magnetic separation of the present invention. As can be seen from the figure, the grade of iron in the selected iron concentrate is 66-80%, and the higher the magnetic field intensity, the higher the grade of iron.
Gelling property of modified steel slag
The modified steel slag obtained in examples 1 to 3 were named T1, T2, T3, and original steel slag T0 and PO 42.5 cement, respectively, and then a mortar strength comparison test was performed to analyze the activity index of the steel slag. Analyzing the particle size distribution of the steel slag powder and the cement by using an LMS-30 type laser particle sizer, wherein the content of particles with the particle size of 0.1-15 mu m in the cement is slightly lower than that of the steel slag powder, the content of the particles of the cement is higher than that of the steel slag powder within the range of the particle size of more than 15 mu m, the total phase difference is small, and the specific surface area of the steel slag powder is 410m2In terms of/kg. The original steel slag powder and the modified steel slag powder respectively replace 30% of P.O 42.5 cement by mass percent, after being uniformly mixed, a cement mortar test is carried out to test the compressive strength of mortar blocks 7d and 28d, and the compressive strength is compared with the compressive strength of a pure cement sample P0, and the test results are shown in Table 1.
TABLE 1 Strength and Activity index of modified Steel slag mortar test piece
As can be seen from Table 1, the early strength of the raw steel slag is low. The compressive strength of 7d is 25.1MPa, the activity index is 65.5 percent, the later strength is slowly improved, the compressive strength of 28d is 36.2MPa, and the activity index is 70.2 percent. Compared with cement, the 7d flexural strength of the original steel slag is 30.1 percent lower, and the compressive strength is 34.5 percent lower. Compared with the original steel slag, the steel slag after high-temperature modification has the advantages that the flexural strength and the compressive strength of 7d and 28d are improved, the increase range of the flexural strength of 7d is 10.4-20.8%, the increase range of the flexural strength of 28d is 16.9-24.6%, the flexural strength of 7d and 28d of a T1 test piece with the highest flexural performance reaches 5.8MPa and 8.1MPa respectively, and the steel slag is improved compared with a T0 test piece20.8% and 24.6% higher. The 7d and 28d compressive strengths of the T1-T3 mortar test piece are 9.16-13.9% and 13.5-17.4% larger than those of the T0 test piece. The compressive strength of 7d and 28d of the steel slag test piece T1 modified at the high temperature of 1150 ℃ is improved by 13.9 percent and 17.4 percent compared with that of a T0 test piece, and respectively reaches 28.6MPa and 42.5MPa, and simultaneously the activity index of the steel slag test piece T1 modified at the high temperature of 1150 ℃ is respectively improved by 9.2 percent and 12.2 percent compared with that of the original steel slag mortar test piece T0, the activity index of 28d reaches 82.4 percent, and the technical requirement that the activity index of first-grade steel slag powder in GB/T20491-2006 Steel slag powder for cement and concrete is more than or equal to 80 percent is met. When the treatment temperature is increased to 1200 ℃ and 1250 ℃, the increase amplitude of the activity indexes of 7d and 28d of the modified steel slag powder is reduced, and when the treatment temperature is 1250 ℃, the activity indexes of 7d and 28d are 71.5 percent and 79.7 percent, which are improved by 6 percent and 9.5 percent compared with T0, but the gelling activity of the steel slag treated at 1150 ℃ is reduced. The experimental result shows that when the treatment temperature is 1150 ℃, the gel phase in the modified steel slag is obviously improved compared with the original steel slag, and the enhancement of the gelling activity of the steel slag is further promoted. Compared with P.O 42.5 cement, the modified steel slag has the gelled phase C3S、C2S、C3The content of A is still lower, so the testing values of the flexural strength and the compressive strength of the mortar of the modified steel slag are lower than those of pure cement. The invention adopts the method of the composite modifier to enhance the gelling activity of the steel slag, and the Ca/Si ratio of the system is improved by selecting cheap high-calcium wastes to prepare the composite modifier, so that the gelling performance of the system can be effectively improved.
Stability of modified steel slag
FIG. 12 is a graph showing the f-Cao and f-MgO contents of the modified steel slag and the original steel slag according to examples 1 to 3 of the present invention, and it can be seen that the composite modifier (reservoir sediment + carbide slag) can significantly reduce the f-MgO and f-CaO contents of the original steel slag during the high temperature modification of the steel slag. When the treatment temperature is 1150 ℃, 1200 ℃ and 1250 ℃, the f-CaO content in the original steel slag is respectively reduced from 2.97 percent to 1.21 percent, 1.58 percent and 1.62 percent, the f-CaO reduction range is respectively 59.3 percent, 47.8 percent and 45.5 percent compared with the original steel slag, and the f-CaO content is increased along with the increase of the treatment temperature; meanwhile, the f-MgO content is respectively reduced from 2.26% to 1.98%, 2.25% and 2.05%Degrees 12.4%, 4.4% and 9.3%. When the temperature reached 1200 ℃, the f-MgO content of the modified steel slag T2 was close to the value of the original steel slag sample T0. While the f-MgO content in the T3 sample with a treatment temperature of 1250 ℃ was reduced by 8.9% compared to that in the T2 sample, which indicates that MgO in the liquid phase participates in the thermochemical reaction of the system, which also verifies MgFe in the XRD analysis of FIG. 22O4Gradually sharp diffraction peak of (a) and a large amount of mineral MgFe appearing in the microstructures of FIG. 7(c) and FIG. 8(c1)2O4The reason for (1).
The main reason for causing the volume instability of the steel slag is the volume expansion caused by hydration of the f-CaO and the f-MgO, and the modified steel slag obtained by modifying the steel slag at high temperature by using the composite modifier can better eliminate the volume instability caused by the f-CaO and the f-MgO. Meanwhile, the steel slag can be directly used in cement concrete without aging treatment at the later stage. The high-temperature treatment can promote the f-CaO and the f-MgO to react with SiO in the composite modifier2、Al2O3The components are subjected to a thermochemical reaction, so that the contents of f-MgO and f-CaO in the steel slag are reduced. However, the steel slag smelted at 1650 ℃ has compact structure, coarse crystal grains and solid solution RO phase, so that the f-MgO and the f-CaO in the high-temperature modification of the steel slag and the chemical components in the composite modifier do not completely react, and the f-CaO and the f-MgO are not completely removed.
In conclusion, the invention utilizes the reservoir sediment, the coal gangue and the iron tailings as the cheap composite modifier, adjusts the composition and the structure of the steel slag, controls the secondary phase reaction, and effectively improves the gelling activity and the stability of the steel slag. The large-scale utilization of the waste is realized, and the purposes of environmental protection, energy conservation and resource utilization are finally achieved.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements, etc. made by those skilled in the art within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. The modified steel slag is characterized by comprising steel slag and a composite modifier, wherein the composite modifier comprises reservoir bottom mud, coal gangue and iron tailings; the steel slag and the composite modifier have the following mass ratio: 70-80: 20-30; the mass ratio of the iron tailings, the reservoir sediment and the coal gangue in the composite modifier is as follows: 3-4: 2-3: 1.
2. the method for preparing modified steel slag according to claim 1, comprising the steps of:
s1, reservoir sediment pretreatment: standing and dehydrating the reservoir bottom mud to enable the water content of the reservoir bottom mud to be 25-35%, then airing and sieving, drying the product under the sieve, and then performing ball milling and homogenization treatment to obtain the pretreated reservoir bottom mud;
s2, coal gangue pretreatment: crushing the coal gangue into particles with the particle size of 1-2 mm by using a jaw crusher, drying for 12 hours at 105 ℃, and ball-milling to 150-200 meshes to obtain pretreated coal gangue;
s3, iron tailing pretreatment: drying the iron tailings at 105 ℃ for 12 hours, and then ball-milling the iron tailings to 150-200 meshes to obtain pretreated iron tailings;
s4, steel slag pretreatment: crushing the steel slag into particles with the particle size of 1-2 mm by using a jaw crusher, drying the particles for 12 hours at 105 ℃, and performing ball milling on the particles to 150-200 meshes to obtain pretreated steel slag;
s5, ball milling and mixing: ball-milling and uniformly mixing the pretreated steel slag, iron tailings, coal gangue and reservoir sediment;
s6, press forming: adding water accounting for 2-5% of the mass of the mixture obtained in the step S5, and performing compression molding;
s7, sintering modification: placing the material cake pressed and formed in the step S6 in a muffle furnace, and sintering and modifying;
s8, blast quenching: and (4) carrying out blast quenching on the steel slag subjected to sintering modification in the step (S7) to obtain the modified steel slag.
3. The preparation method of the modified steel slag according to claim 2, wherein the bottom mud in the reservoir is left to stand and dehydrate for 7 days in the step S1, stirred for 1 time every day, and subjected to pressure filtration to ensure that the water content is 25-35%; the ball milling is carried out in a cement ball mill for 5-15 min, and the ball milling speed is 25.4 r/min.
4. The method for preparing modified steel slag according to claim 2, wherein the reservoir sediment obtained in step S1 comprises the following main components in percentage by weight: SiO 2240～60％，Al2O310～30％，Fe2O31～15％，MgO1～5％，CaO3～10％，Na2O0.1～5％，K2O0.1～5％，P2O50.01～3％，TiO20.01-3% and loss on ignition of 1-20%.
5. The method for preparing modified steel slag according to claim 2, wherein the steel slag in step S4 comprises the following main components in percentage by weight: SiO 2210～20％，Al2O31～7％，Fe2O32～33％，MgO3～12％，CaO30～50％，FeO3～15％，Na2O0.01～3％，K2O0.01～3％，SO30.26％，P2O51～6％。
6. The method for preparing modified steel slag according to claim 2, wherein the gangue in step S2 comprises the following main components in percentage by weight: SiO 2220～60％，Al2O310～40％，Fe2O30.1～10％，FeO0.1～10％，MgO0.01～6％，CaO0.01～6％，K2O0.01～5％，SO20.01-10% and loss on ignition of 5-40%.
7. The method for preparing modified steel slag according to claim 2, wherein in step S6, the pressure for press forming is 15-35 MPa.
8. The method for preparing modified steel slag according to any one of claims 2 to 7, wherein the sintering modification is: raising the temperature to 1150-1250 ℃ at a speed of 10 ℃/min, and preserving the heat for 25 min.
9. The modified steel slag prepared by the preparation method of the modified steel slag according to any one of claims 2 to 8 is efficiently utilized, wherein the modified steel slag obtained in the step S8 is ground into 200 meshes by a ball mill, and then is placed into a 1-2T strong magnetic separator for magnetic separation to obtain fine iron powder and modified steel slag powder, and the modified steel slag powder is applied to the preparation of cement concrete.
10. The efficient utilization of the modified steel slag according to claim 9, wherein the rotating speed of the magnetic separator is 10-20 r/min.
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