CN112322257B - Modified steel slag, preparation method thereof and heat storage material - Google Patents
Modified steel slag, preparation method thereof and heat storage material Download PDFInfo
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Abstract
The invention belongs to the field of heat storage materials, and relates to modified steel slag, a preparation method thereof and a heat storage material, wherein the preparation method comprises the following steps: (1) mixing a modifier with the steel slag to obtain a mixture, wherein the modifier comprises carbonate; (2) and sintering the mixture for the first time to obtain the modified steel slag. According to the invention, before the steel slag is prepared into the heat storage material, the carbonate is added to prepare the mixture, and through the sintering modification step, the carbonate and the steel slag are fully reacted in the sintering process, so that the chemical property is more stable, the heat storage density is greatly improved, and compared with the unmodified steel slag, the heat storage density is improved by more than 25.32%.
Description
Technical Field
The invention belongs to the field of heat storage materials, relates to modified steel slag, a preparation method thereof and a heat storage material, and particularly relates to a carbonate modified steel slag heat storage material, a preparation method thereof and a heat storage material.
Background
The steel slag in China has high yield but low utilization rate, and most of the steel slag is stacked or buried, thereby causing serious environmental pollution. The steel slag meets the requirement of strong thermal stability of the heat storage material, and has low cost and high heat conductivity coefficient, and if the steel slag is used as the heat storage material, the steel slag has great significance for improving the resource utilization rate, protecting the environment and reducing the preparation cost of the heat storage material.
Wang et al ("Thermal properties and friction properties of slag as Energy storage Solar power plants", Solar Energy Materials and Solar Cells, 2018, 182:21-29) studied the thermophysical properties of two arc slags. The results show that the average specific heat capacity of the two types of slag is 0.82kJ (/ kg. K), and the slag is slightly different from the traditional shaping materials such as silicon dioxide, magnesium oxide, diatomite and the like; the thermal conductivity is 1.70W/(m.K), is relatively low and is higher than that of paraffin, hydrated salt and molten salt phase change materials; the steel slag has low cost, which is only 9 percent of silicon dioxide and 2.5 percent of expanded graphite. Therefore, the steel slag is still a potential heat storage material. Agalit et al ("thermal and chemical conversion of absorption furnace slag for high temperature thermal Energy storage in Solar Energy plants", Solar Energy Materials and Solar Cells, 2017, 172: 168-. Thermal stability from room temperature to 1000 ℃ was tested by thermogravimetric analysis (TGA); the material was heated/cooled three times and its thermal stability was verified at the end of the first cycle, which is considered a good backup material for high temperature heat storage applications (up to 1000 ℃).
CN103755283A discloses a method for preparing heat storage concrete by utilizing smelting steel slag. The prepared heat storage concrete has outstanding comprehensive performance of compression resistance and rupture strength at the high temperature stage of 200-. CN102898106A discloses a high-density heat-storage concrete and a preparation method thereof. The material is prepared from aggregate consisting of sulphoaluminate cement, steel slag and basalt, graphite, slag powder, water and a water reducing agent; and through a large amount of experiments, the aggregate is tightly stacked, the compactness of the concrete is improved, and the heat storage density of the concrete is improved.
Most of the researches are directly utilizing the steel slag or only simply mixing the steel slag before pressure forming for compact compaction, and in order to overcome the defect of low heat storage density of the steel slag and further improve the performance of the steel slag, an improved preparation process for the steel slag is required to be provided.
Disclosure of Invention
In view of the above problems in the prior art, the present invention is directed to a modified steel slag, a method for preparing the same, and a heat storage material.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a method for preparing modified steel slag, comprising the following steps:
(1) mixing a modifier with the steel slag to obtain a mixture, wherein the modifier comprises carbonate;
(2) and sintering the mixture for the first time to obtain the modified steel slag.
The steel slag can be directly applied to sensible heat storage materials, but the heat storage density is lower, the heat storage density is 797.95kJ/kg (400 ℃ C. and 900 ℃ C.), and the industrial application is not facilitated. Aiming at the problems, before the steel slag is prepared into the heat storage material, the modifier containing carbonate is added to prepare the mixture, and through the sintering modification step, the carbonate and the steel slag fully react in the sintering process, so that the chemical property is more stable, the heat storage density is greatly improved, and compared with the unmodified steel slag, the heat storage density is improved by more than 25.32%.
In the method, the mixture containing the carbonate and the steel slag is heated to the temperature at which the carbonate is molten in one sintering, and the molten carbonate is adsorbed into the pores of the steel slag under the action of capillary tubes and is in close contact with the steel slag, so that the carbonate and the steel slag are reacted more fully.
The technical principle is as follows: SiO in steel slag2By substitution reaction with carbonate in molten state to produce CO2And silicates, Al2O3、SiO2Reacting with molten carbonate to produce aluminosilicate, CaO, SiO2Reacting with molten carbonate to form calcium silicate.
The chemical reaction equation is as follows:
CaO+SiO2＝CaSiO3
Na2CO3+SiO2＝Na2SiO3+CO2(g)
Na2CO3+Al2O3＝2NaAlO2+CO2(g)
Na2CO3+Al2O3+2SiO2＝2NaAlSiO4+CO2(g)
Na2CO3+CaO+SiO2＝Na2CaSiO4+CO2(g)。
in the method of the present invention, the source of the carbonate is not particularly limited, and for example, the carbonate may be directly added, or a raw material capable of decomposing into carbonate may be added for the reaction decomposition to produce carbonate. By way of example, bicarbonate can be used in the reaction of the present invention, which decomposes during heating to produce carbonate.
As a preferred technical scheme of the method, the method also comprises the step (3) after the step (2): and pressing and forming the modified steel slag to obtain shaped steel slag, and performing secondary sintering to obtain the modified steel slag heat storage material.
The preferable scheme provides a preparation method of the two-section modified steel slag, and the modified steel slag is pressed and formed and then sintered again, so that the obtained carbonate modified steel slag heat storage material has good appearance and high heat storage density. The carbonate modified steel slag heat storage material and the preparation method thereof further improve the effective application of the steel slag and reduce the waste amount of the steel slag.
Preferably, the steel slag of step (1) has a main composition comprising SiO2、Al2O3CaO and Fe2O3. The invention does not limit other components in the steel slag in particular, and generally comprises a small amount of MgO and TiO2Or other oxides.
Preferably, the carbonate salt in step (1) comprises any one of sodium carbonate, lithium carbonate and potassium carbonate or a combination of at least two thereof, and typical but non-limiting combinations include a combination of sodium carbonate and lithium carbonate, a combination of sodium carbonate and potassium carbonate, a combination of lithium carbonate and potassium carbonate, or a combination of sodium carbonate, lithium carbonate and potassium carbonate, preferably sodium carbonate. Further preferred is sodium carbonate.
Preferably, the mass ratio of the carbonate to the steel slag in the modifier in the step (1) (2-4: 4), for example, 2:4, 2.5:4, 3:4, 3.5:4, 3.8:4 or 4:4, etc., preferably 3: 4.
In the invention, the heat storage density of the material can be adjusted by adjusting the dosage ratio of the carbonate to the steel slag, and higher heat storage density can be obtained within the preferable range. It should be noted that if the amount of carbonate used is too large, the obtained heat storage material may be deformed and leaked, and thus, the heat storage material cannot be practically used.
As another preferred embodiment of the method of the present invention, the method further comprises pretreating the modifier before step (1): and performing ball milling treatment and drying treatment on the modifier in sequence.
Preferably, the particle size D50 of the modifier after ball milling is 45-90 μm, such as 45 μm, 50 μm, 60 μm, 70 μm, 80 μm or 90 μm. If the particle size of the modifier is too large, the carbonate is heated unevenly during heating, so that the molten modifier is not beneficial to the reaction with the steel slag; if the particles of the modifier are too small, the processing difficulty is high, the processing time is long, and the preparation efficiency of the modified steel slag is not improved. Further preferably 45 to 60 μm.
Preferably, the temperature for drying the modifier is 100-130 ℃, for example, 100 ℃, 105 ℃, 110 ℃, 120 ℃ or 130 ℃, preferably 115-125 ℃.
Preferably, the drying treatment is carried out for 6 to 12 hours, for example, 6 hours, 8 hours, 10 hours, 11 hours or 12 hours, preferably 10 to 12 hours.
Preferably, the method further comprises pretreating the steel slag before the step (1): the steel slag is sequentially subjected to ball milling treatment and drying treatment.
Preferably, the particle size D50 of the steel slag after ball milling treatment is 20-65 μm, such as 25 μm, 3 μm, 40 μm, 50 μm, 60 μm or 65 μm. If the particle size of the steel slag is too large and the specific surface area is too small, the molten carbonate and the steel slag are not in full contact reaction, and if the particle size of the steel slag is too small, the processing difficulty is high, the processing time is long, and the preparation efficiency of the preparation method of the carbonate modified steel slag is not improved. More preferably 35 to 50 μm.
Preferably, the temperature for drying the steel slag is 100-130 ℃, for example, 100 ℃, 105 ℃, 110 ℃, 120 ℃ or 130 ℃, preferably 120 ℃.
Preferably, the drying treatment time of the steel slag is 6 to 12 hours, such as 6 hours, 8 hours, 10 hours, 11 hours or 12 hours, preferably 10 to 12 hours.
Preferably, the melting temperature of the carbonate in the step (2) is 20 to 100 ℃ higher than the melting temperature of the carbonate (for example, 20 ℃, 40 ℃, 60 ℃, 80 ℃ or 100 ℃) and more preferably 40 to 80 ℃ higher than the melting temperature of the carbonate. Taking sodium carbonate, lithium carbonate and potassium carbonate as an example, when the mass proportion of the carbonate is different, the melting temperature of the carbonate is changed correspondingly, the sintering modification temperature is selected to be 20-100 ℃ higher than the melting temperature of the carbonate, and in the temperature range, the molten carbonate can be in contact reaction with the steel slag better.
Preferably, the time of the primary sintering in the step (2) is 1 to 5 hours, for example, 1, 1.5 hours, 2 hours, 3 hours, 3.5 hours, 4 hours or 5 hours, preferably 3 to 5 hours.
Preferably, the temperature rise rate of the primary sintering in the step (2) is 1-20 ℃/min, for example, 1 ℃/min, 3 ℃/min, 5 ℃/min, 8 ℃/min, 10 ℃/min, 12 ℃/min, 15 ℃/min, 18 ℃/min, or 20 ℃/min, preferably 5-10 ℃/min.
Preferably, the pressure in the press forming in the step (3) is 6-12MPa, and can be 6, 8, 9, 10, 11 or 12MPa, for example. .
Preferably, the time for the press forming in step (3) is 1-3min, and may be 1min, 1.5min, 2min, 2.5min or 3min, for example.
When the invention is used for compression molding, if the compression molding pressure is high, the compression molding time is short, and if the compression molding pressure is low, the compression molding time is long.
Preferably, the step (3) is to press-form the modified steel slag into a cylinder.
Preferably, the diameter of the cylinder is 10-50mm, for example 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm or 50mm, preferably 15-30 mm.
Preferably, the thickness of the cylinder is 2-4mm, and may be, for example, 2mm, 2.5mm, 3mm, 3.5mm or 4mm, preferably 2 mm.
The specific surface area of the cylinder with large diameter and small thickness is large, when the cylinder with large specific surface area is sintered, the modified steel slag in the cylinder is heated uniformly, the modified steel slag is combined more tightly, the formed carbonate modified steel slag heat storage material has good forming degree, and the cracking phenomenon can not occur.
Preferably, the temperature of the secondary sintering in the step (3) is 10 to 50 ℃ higher than the melting temperature of the carbonate (for example, 10 ℃, 20 ℃, 30 ℃ or 50 ℃), and more preferably 30 to 50 ℃ higher than the melting temperature of the carbonate.
Preferably, the time of the secondary sintering in the step (3) is 60-180min, for example, 60min, 70min, 80min, 90min, 100min, 110min, 120min, 130min, 140min, 150min, 160min, 170min or 180min, preferably 90-150 min.
Preferably, the temperature rise rate of the secondary sintering in the step (3) is 1-20 ℃/min, for example, 1 ℃/min, 3 ℃/min, 5 ℃/min, 8 ℃/min, 10 ℃/min, 12 ℃/min, 15 ℃/min, 18 ℃/min, or 20 ℃/min, preferably 5-10 ℃/min.
As a further preferred technical solution of the method of the present invention, the method comprises the steps of:
(a) ball-milling carbonate until the particle diameter D50 is 45-90 μm, and drying at 100-130 deg.C for 6-12 h;
ball-milling the steel slag until D50 is 20-65 μm, and drying at 100-130 deg.C for 6-12h for later use;
uniformly mixing the treated carbonate and the steel slag according to the mass ratio of (2-4) to (4) to obtain a mixture;
(b) heating to 20-100 ℃ higher than the melting temperature of the carbonate at the heating rate of 1-20 ℃/min, and sintering the mixture for 1-5 hours at the sintering temperature to obtain the modified steel slag;
(c) pressing the modified steel slag obtained in the step (b) for 1-3min under the pressure condition of 6-12MPa to obtain cylindrical shaped steel slag with the diameter of 10-50mm and the thickness of 2-4 mm;
(d) heating to 10-50 ℃ higher than the melting temperature of the carbonate at the heating rate of 1-20 ℃/min, and sintering the cylindrical shaped steel slag obtained in the step (c) for 60-180min to obtain the carbonate modified steel slag heat storage material.
The preferable technical scheme provides a method for preparing the carbonate modified steel slag heat storage material by using a carbonate modification method, wherein the carbonate modification method comprises the steps of sintering and modifying a mixture of carbonate and steel slag, pressing and molding the mixture, and then sintering the mixture, the carbonate modification method is adopted to enable the carbonate and the steel slag to react fully, the chemical stability is good, the prepared carbonate modified steel slag heat storage material has high heat storage density, the steel slag can be effectively applied, and the waste amount of the steel slag is reduced.
According to the preferable technical scheme, the steel slag is sintered and modified by carbonate, the problem of incomplete reaction of carbonate and the steel slag caused by direct sintering and molding is solved by the arrangement of the primary sintering and modification step, the chemical stability of the obtained carbonate modified steel slag is enhanced by combining the processes of press molding and secondary sintering, the molding degree is good, no crack is generated, the heat storage density is greatly improved, the heat storage density is 997-doped 1066kJ/kg (400-doped 900 ℃), and the heat storage density is improved by more than 25.32% compared with the unmodified steel slag.
In a second aspect, the present invention provides a modified steel slag prepared by the preparation method of the first aspect.
In a third aspect, the invention provides a heat storage material, which comprises the modified steel slag of the second aspect. Specifically, the modified steel slag of the second aspect can be used alone; can also be used together with steel slag from other sources.
In the invention, the modified steel slag obtained in the step (2) and the modified steel slag heat storage material obtained in the step (4) can be used as heat storage materials.
Compared with the prior art, the invention has the following beneficial effects:
before the steel slag is prepared into the heat storage material, carbonate is added
The mixture is prepared, and through the sintering modification step, the carbonate and the steel slag are fully reacted in the sintering process, so that the chemical property is more stable, and the heat storage density is greatly improved.
According to the preferable scheme, the steel slag is modified by sintering carbonate, the problem of incomplete reaction of carbonate and the steel slag caused by direct sintering and molding is solved by the arrangement of the primary sintering and modification step, the chemical stability of the obtained carbonate modified steel slag is enhanced by combining the processes of press molding and secondary sintering, the molding degree is good, no crack is generated, the heat storage density is greatly improved, the heat storage density is 997-doped steel slag 1066kJ/kg (400-doped 900 ℃), and is improved by more than 25.32% compared with the unmodified steel slag.
Drawings
FIG. 1 is a flow chart of the preparation of the carbonate modified steel slag heat storage material provided by the invention;
FIG. 2 is a diagram of a sample of the carbonate-modified steel slag heat storage material provided in example 1;
FIG. 3 is a diagram showing a sample of the steel slag heat storage material provided in comparative example 1;
fig. 4 is a heat storage performance (DCS) test chart of the carbonate modified steel slag heat storage material provided in example 1 and the steel slag heat storage material of comparative example 1.
Detailed Description
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.
The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
In the examples of the present invention, the steel slag composition is shown in table 1:
TABLE 1
| Substance(s) | CaO | SiO2 | Fe2O3 | Al2O3 | MgO | TiO2 | Others |
| Content/wt% | 38.324 | 30.246 | 11.293 | 9.199 | 5.219 | 1.751 | 3.968 |
Example 1
The embodiment provides a preparation method of a carbonate modified steel slag heat storage material (see a preparation flow chart in figure 1), which comprises the following steps:
(a) ball-milling sodium carbonate until D50 is 50 μm, and drying at 100 deg.C for 10h to obtain pretreated sodium carbonate;
ball-milling the steel slag until D50 is 50 μm, and drying at 100 ℃ for 10h to obtain pretreated steel slag;
uniformly mixing the treated sodium carbonate and the treated steel slag according to the mass ratio of 4: 4;
(b) heating to 950 ℃ at the heating rate of 5 ℃/min, and sintering the mixed material obtained in the step (a) at 950 ℃ for 2h to obtain modified steel slag;
(c) pressing the modified steel slag obtained in the step (b) for 3min under 6MPa to obtain a cylinder with the diameter of 20mm and the thickness of 2 mm;
(d) and (c) heating to 900 ℃ at the heating rate of 5 ℃/min, sintering the column obtained in the step (c) for 60min, and naturally cooling to obtain the carbonate modified steel slag heat storage material.
The obtained carbonate modified steel slag heat storage material is shown in figure 2, the DCS test chart is shown in figure 4, as can be seen from figure 2, the obtained carbonate modified steel slag heat storage material has good formability, the surface has no cracking phenomenon, as can be seen from figure 4, the heat storage density of the obtained carbonate modified steel slag heat storage material is 1066kJ/kg (400-.
Example 2
The embodiment provides a preparation method of a two-section carbonate heat storage material, which comprises the following steps:
(a) ball-milling sodium carbonate until D50 is 40 μm, and drying at 105 deg.C for 8h to obtain pretreated sodium carbonate;
ball-milling the steel slag until D50 is 40 μm, and drying at 105 ℃ for 8h to obtain pretreated steel slag;
uniformly mixing the treated sodium carbonate and the treated steel slag according to the mass ratio of 3: 4;
(b) heating to 930 ℃ at the heating rate of 10 ℃/min, and sintering the mixed material obtained in the modification step (a) at 930 ℃ for 3 hours to obtain modified steel slag;
(c) pressing the premix obtained in the step (b) for 2.5min under 8MPa to obtain a cylinder with the diameter of 15mm and the thickness of 1.5 mm;
(d) and (c) heating to 890 ℃ at the heating rate of 10 ℃/min, sintering the column obtained in the step (c) for 120min, and naturally cooling to obtain the carbonate modified heat storage material.
The obtained carbonate modified steel slag heat storage material has good formability, and no surface cracking phenomenon, and the heat storage density of the obtained carbonate modified steel slag heat storage material is 1024kJ/kg (400-.
Example 3
The embodiment provides a preparation method of a carbonate modified steel slag heat storage material, which comprises the following steps:
(a) ball-milling sodium carbonate until D50 is 45 μm, and drying at 110 deg.C for 6h to obtain pretreated sodium carbonate;
ball-milling the steel slag until D50 is 45 mu m, and drying at 110 ℃ for 6h to obtain pretreated steel slag;
uniformly mixing the treated carbonate with the treated steel slag according to the mass ratio of 2: 4;
(b) heating to 900 ℃ at the heating rate of 15 ℃/min, and sintering the mixed material obtained in the modification step (a) at 900 ℃ for 4h to obtain modified steel slag;
(c) pressing the premix obtained in the step (b) for 2min under 10MPa to obtain a cylinder with the diameter of 30mm and the thickness of 2 mm;
(d) and (c) heating to 880 ℃ at the heating rate of 15 ℃/min, sintering the column obtained in the step (c) for 150min, and naturally cooling to obtain the carbonate modified steel slag heat storage material.
The obtained carbonate modified steel slag heat storage material has good formability, and no surface cracking phenomenon, and the heat storage density of the obtained carbonate modified steel slag heat storage material is 997kJ/kg (400-.
Example 4
The embodiment provides a preparation method of a carbonate modified steel slag heat storage material (see a preparation flow chart in figure 1), which comprises the following steps:
(a) ball milling potassium carbonate until D50 is 50 μm, and drying at 100 deg.C for 10h to obtain pretreated potassium carbonate;
ball-milling the steel slag until D50 is 50 μm, and drying at 100 ℃ for 10h to obtain pretreated steel slag;
uniformly mixing the treated potassium carbonate and the treated steel slag according to the mass ratio of 4: 4;
(b) heating to 950 ℃ at the heating rate of 5 ℃/min, and sintering the mixed material obtained in the step (a) at 950 ℃ for 2h to obtain modified steel slag;
(c) pressing the modified steel slag obtained in the step (b) for 3min under 6MPa to obtain a cylinder with the diameter of 20mm and the thickness of 2 mm;
(d) and (c) heating to 900 ℃ at the heating rate of 5 ℃/min, sintering the column obtained in the step (c) for 60min, and naturally cooling to obtain the carbonate modified steel slag heat storage material.
The obtained carbonate modified steel slag heat storage material has good formability, and no surface cracking phenomenon, and the heat storage density of the obtained carbonate modified steel slag heat storage material is 1013kJ/kg (400-.
Example 5
The embodiment provides a preparation method of a carbonate modified steel slag heat storage material (see a preparation flow chart in figure 1), which comprises the following steps:
(a) ball-milling sodium carbonate until D50 is 50 μm, and drying at 100 deg.C for 10h to obtain pretreated sodium carbonate;
ball-milling the steel slag until D50 is 50 μm, and drying at 100 ℃ for 10h to obtain pretreated steel slag;
uniformly mixing the treated sodium carbonate and the treated steel slag according to the mass ratio of 0.5: 4;
(b) heating to 950 ℃ at the heating rate of 5 ℃/min, and sintering the mixed material obtained in the step (a) at 950 ℃ for 2h to obtain modified steel slag;
(c) pressing the modified steel slag obtained in the step (b) for 3min under 6MPa to obtain a cylinder with the diameter of 20mm and the thickness of 2 mm;
(d) and (c) heating to 900 ℃ at the heating rate of 5 ℃/min, sintering the column obtained in the step (c) for 60min, and naturally cooling to obtain the carbonate modified steel slag heat storage material.
The obtained carbonate modified steel slag heat storage material has good formability, and no surface cracking phenomenon, and the heat storage density of the obtained carbonate modified steel slag heat storage material is 822kJ/kg (400-.
Example 6
The embodiment provides a preparation method of a carbonate modified steel slag heat storage material (see a preparation flow chart in figure 1), which comprises the following steps:
(a) ball-milling sodium carbonate until D50 is 50 μm, and drying at 100 deg.C for 10h to obtain pretreated sodium carbonate;
ball-milling the steel slag until D50 is 50 μm, and drying at 100 ℃ for 10h to obtain pretreated steel slag;
uniformly mixing the treated sodium carbonate and the treated steel slag according to the mass ratio of 10: 4;
(b) heating to 950 ℃ at the heating rate of 5 ℃/min, and sintering the mixed material obtained in the step (a) at 950 ℃ for 2h to obtain modified steel slag;
(c) pressing the modified steel slag obtained in the step (b) for 3min under 6MPa to obtain a cylinder with the diameter of 20mm and the thickness of 2 mm;
(d) and (c) heating to 900 ℃ at the heating rate of 5 ℃/min, sintering the column obtained in the step (c) for 60min, and naturally cooling to obtain the carbonate modified steel slag heat storage material.
The obtained carbonate modified steel slag heat storage material has deformation leakage and cannot be practically used.
Example 7
The embodiment provides a preparation method of a carbonate modified steel slag heat storage material (see a preparation flow chart in figure 1), which comprises the following steps:
(a) ball-milling sodium carbonate until D50 is 120 μm, and drying at 100 deg.C for 10h to obtain pretreated sodium carbonate;
ball-milling the steel slag until D50 is 50 μm, and drying at 100 ℃ for 10h to obtain pretreated steel slag;
uniformly mixing the treated sodium carbonate and the treated steel slag according to the mass ratio of 4: 4;
(b) heating to 950 ℃ at the heating rate of 5 ℃/min, and sintering the mixed material obtained in the step (a) at 950 ℃ for 2h to obtain modified steel slag;
(c) pressing the modified steel slag obtained in the step (b) for 3min under 6MPa to obtain a cylinder with the diameter of 20mm and the thickness of 2 mm;
(d) and (c) heating to 900 ℃ at the heating rate of 5 ℃/min, sintering the column obtained in the step (c) for 60min, and naturally cooling to obtain the carbonate modified steel slag heat storage material.
The obtained carbonate modified steel slag heat storage material has good formability, and no surface cracking phenomenon, and the heat storage density of the obtained carbonate modified steel slag heat storage material is 1021kJ/kg (400-.
Example 8
The embodiment provides a preparation method of a carbonate modified steel slag heat storage material (see a preparation flow chart in figure 1), which comprises the following steps:
(a) ball-milling sodium carbonate until D50 is 50 μm, and drying at 100 deg.C for 10h to obtain pretreated sodium carbonate;
ball-milling the steel slag until D50 is 50 μm, and drying at 100 ℃ for 10h to obtain pretreated steel slag;
uniformly mixing the treated sodium carbonate and the treated steel slag according to the mass ratio of 4: 4;
(b) heating to 950 ℃ at the heating rate of 5 ℃/min, and sintering the mixed material obtained in the step (a) at 950 ℃ for 2h to obtain modified steel slag;
the surface of the obtained modified steel slag is full of a large number of pores and has a cracking phenomenon, so that the modified steel slag cannot be practically used.
Comparative example 1
The comparative example provides a preparation method of a steel slag heat storage material, which comprises the following steps:
(a) ball-milling the steel slag until D50 is 50 μm, and drying at 100 ℃ for 10h to obtain pretreated steel slag;
(b) pressing the steel slag for 3min under 6MPa to obtain a cylinder with the diameter of 20mm and the thickness of 2 mm;
(c) and (c) heating to 900 ℃ at the heating rate of 5 ℃/min, sintering the column obtained in the step (b) for 60min, and naturally cooling to obtain the steel slag heat storage material.
The obtained steel slag heat storage material has larger gaps on the surface (as shown in fig. 3), and a DCS test chart is shown in fig. 4, and the DCS test shows that the obtained steel slag heat storage material has the heat storage density of 797.95kJ/kg (400-.
The applicant states that the present invention is illustrated in detail by the above examples, but the present invention is not limited to the above detailed methods, i.e. it is not meant that the present invention must rely on the above detailed methods for its implementation. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (33)
1. A preparation method of a modified steel slag heat storage material is characterized by comprising the following steps:
(1) mixing a modifier with the steel slag to obtain a mixture, wherein the modifier comprises carbonate, and the mass ratio of the carbonate to the steel slag in the modifier in the step (1) is (2-4) to 4;
(2) carrying out primary sintering on the mixture to obtain modified steel slag; step (3) is performed after step (2): pressing and forming the modified steel slag to obtain shaped steel slag, and performing secondary sintering to obtain a modified steel slag heat storage material;
pretreating the modifier before the step (1): performing ball milling treatment and drying treatment on a modifier in sequence, wherein the particle size D50 of the modifier subjected to ball milling treatment is 45-90 μm; the steel slag in the step (1) mainly comprises SiO2、Al2O3CaO, and Fe2O3；
The carbonate in the step (1) comprises any one or a combination of at least two of sodium carbonate, lithium carbonate and potassium carbonate;
the method also comprises the following steps of pretreating the steel slag before the step (1): carrying out ball milling treatment and drying treatment on the steel slag in sequence;
the temperature of the primary sintering in the step (2) is 20-100 ℃ higher than the melting temperature of the carbonate;
the temperature of the secondary sintering in the step (3) is 10-50 ℃ higher than the melting temperature of the carbonate.
2. The process according to claim 1, wherein the carbonate in step (1) is sodium carbonate.
3. The method according to claim 1, wherein the mass ratio of the carbonate to the steel slag in the modifier in the step (1) is 3: 4.
4. The method as claimed in claim 1, wherein in the step of pretreating the modifier before the step (1), the particle size D50 of the modifier after ball milling is 45-60 μm.
5. The method as claimed in claim 1, wherein the temperature for drying the modifier is 100-130 ℃.
6. The method as claimed in claim 5, wherein the temperature for drying the modifier is 115-125 ℃.
7. The method of claim 1, wherein the modifier is dried for a period of time ranging from 6 to 12 hours.
8. The method according to claim 1, wherein the drying treatment is carried out for a time of 10 to 12 hours.
9. The method as claimed in claim 1, wherein the steel slag has a particle size D50 of 20-65 μm after ball milling.
10. The method as claimed in claim 9, wherein the steel slag has a particle size D50 of 35-50 μm after ball milling.
11. The method as claimed in claim 1, wherein the temperature for drying the steel slag is 100-130 ℃.
12. The method according to claim 11, wherein the temperature for drying the steel slag is 120 ℃.
13. The method as claimed in claim 1, wherein the drying treatment of the steel slag is performed for 6 to 12 hours.
14. The method as claimed in claim 13, wherein the drying treatment of the steel slag is performed for 10-12 hours.
15. The method according to claim 1, wherein the temperature of the primary sintering in the step (2) is 40-80 ℃ higher than the melting temperature of the carbonate.
16. The method according to claim 1, wherein the time for the primary sintering in the step (2) is 1-5 h.
17. The method according to claim 1, wherein the time for the primary sintering in the step (2) is 3-5 h.
18. The method according to claim 1, wherein the temperature rise rate of the primary sintering in the step (2) is 1-20 ℃/min.
19. The method according to claim 1, wherein the temperature rise rate of the primary sintering in the step (2) is 5-10 ℃/min.
20. The method according to claim 1, wherein the pressure in the press forming in the step (3) is 6 to 12 MPa.
21. The method according to claim 1, wherein the press-forming time of step (3) is 1-3 min.
22. The method of claim 1, wherein the step (3) is performed by pressing the modified steel slag into a cylinder.
23. The method of claim 22, wherein the diameter of the cylinder is 10-50 mm.
24. The method of claim 22, wherein the diameter of the cylinder is 15-30 mm.
25. The method of claim 22, wherein the thickness of the cylinder is 2-4 mm.
26. The method of claim 25, wherein the thickness of the cylinder is 2 mm.
27. The method according to claim 1, wherein the temperature of the secondary sintering of step (3) is 30-50 ℃ higher than the melting temperature of the carbonate.
28. The method of claim 1, wherein the time for the secondary sintering in step (3) is 60-180 min.
29. The method of claim 28, wherein the time for the secondary sintering in step (3) is 90-150 min.
30. The method according to claim 1, wherein the temperature increase rate of the secondary sintering in the step (3) is 1-20 ℃/min.
31. The method as claimed in claim 30, wherein the temperature increase rate of the secondary sintering in the step (3) is 5-10 ℃/min.
32. Method according to claim 1, characterized in that it comprises the following steps:
(a) ball-milling carbonate until the particle diameter D50 is 45-90 μm, and drying at 100-130 deg.C for 6-12 h;
ball-milling the steel slag until D50 is 20-65 μm, and drying at 100-130 deg.C for 6-12h for later use;
uniformly mixing the treated carbonate and the steel slag according to the mass ratio of (2-4) to (4) to obtain a mixture;
(b) heating to 20-100 ℃ higher than the melting temperature of the carbonate at the heating rate of 1-20 ℃/min, and sintering the mixture for 1-5 hours at the sintering temperature to obtain the modified steel slag;
(c) pressing the modified steel slag obtained in the step (b) for 1-3min under the pressure condition of 6-12MPa to obtain cylindrical shaped steel slag with the diameter of 10-50mm and the thickness of 2-4 mm;
(d) heating to 10-50 ℃ higher than the melting temperature of the carbonate at the heating rate of 1-20 ℃/min, and sintering the cylindrical shaped steel slag obtained in the step (c) for 60-180min to obtain the modified steel slag heat storage material.
33. A modified steel slag heat storage material prepared by the method of any one of claims 1 to 32.
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