Red mud-based composite calcium ferrite and preparation method and application thereof
阅读说明：本技术 一种赤泥基复合铁酸钙及其制备方法和应用 (Red mud-based composite calcium ferrite and preparation method and application thereof ) 是由 张延玲 赵峥 张威风 余阚 张尧 于 2021-10-19 设计创作，主要内容包括：本发明提供了一种赤泥基复合铁酸钙及其制备方法和应用,属于冶金技术领域。本发明中复合铁酸钙的制备方法包括以下步骤：将赤泥与钙源进行混合,将所得混合料在含氧气氛下进行焙烧,得到赤泥基复合铁酸钙；所述钙源包括石灰或碳酸钙。本发明利用固体废弃物赤泥制备复合铁酸钙,原料成本大幅降低,另一方面,所制备得到的复合铁酸钙与传统铁酸钙相比,物相结构主要为CaFe-(2)O-(4)、Ca-(2)FeAlO-(5)和Ca-(2)Fe-(2)O-(5),其熔点更低、石灰溶解效率更高,在钢水初炼及精炼流程中应用时助熔和脱磷效果更优,具有广阔的工业应用前景。(The invention provides red mud-based composite calcium ferrite and a preparation method and application thereof, belonging to the technical field of metallurgy. The preparation method of the composite calcium ferrite comprises the following steps: mixing red mud and a calcium source, and roasting the obtained mixture in an oxygen-containing atmosphere to obtain red mud-based composite calcium ferrite; the calcium source comprises lime or calcium carbonate. According to the invention, the solid waste red mud is utilized to prepare the composite calcium ferrite, the raw material cost is greatly reduced, and on the other hand, compared with the traditional calcium ferrite, the prepared composite calcium ferrite mainly has a CaFe phase structure 2 O 4 、Ca 2 FeAlO 5 And Ca 2 Fe 2 O 5 The melting point is lower, the lime dissolving efficiency is higher, the fluxing and dephosphorization effects are better when the lime dissolving agent is applied to the primary smelting and refining processes of molten steel, and the lime dissolving agent has wide application rangeAnd industrial application prospect.)
1. A preparation method of red mud-based composite calcium ferrite comprises the following steps:
mixing red mud and a calcium source, and roasting the obtained mixture in an oxygen-containing atmosphere to obtain red mud-based composite calcium ferrite; the calcium source comprises lime or calcium carbonate.
2. The preparation method according to claim 1, wherein the red mud is used in an amount of Fe2O3Based on the molar content of CaO, the calcium source being used in an amount corresponding to the molar content of CaO, and the Fe2O3The mol ratio of the CaO to the CaO is 1: 0.8-1.
3. The preparation method of claim 1, wherein the roasting temperature is 1000-1200 ℃; the heat preservation time is 0.5-2 h.
4. The method of claim 1, further comprising, prior to the firing, pressing the mixture into a briquette.
5. The preparation method according to claim 1, wherein Fe in the red mud2O3In an amount of>40wt％，Al2O3The content of (B) is 10-15 wt%.
6. The method of claim 1, wherein the lime has an available calcium oxide content of greater than 80 wt%, and the calcium carbonate has an available calcium oxide content of greater than 50 wt%.
7. The production method according to claim 1, wherein the oxygen-containing atmosphere includes an air atmosphere or an oxygen atmosphere.
8. The red mud-based composite calcium ferrite prepared by the preparation method of any one of claims 1 to 7, which comprises CaFe2O4、Ca2FeAlO5And Ca2Fe2O5。
9. The red mud-based composite calcium ferrite according to claim 8, wherein the red mud-based composite calcium ferrite comprises 5-15% of CaFe by mass percentage2O4、5～15％Ca2FeAlO5And 70-90% of Ca2Fe2O5。
10. The use of the red mud-based composite calcium ferrite according to claim 8 or 9 in steel making.
Technical Field
The invention relates to the technical field of metallurgy, in particular to red mud-based composite calcium ferrite and a preparation method and application thereof.
Background
Calcium ferrite is a well-known excellent steelmaking flux and dephosphorizing agent. The calcium ferrite has low melting point and high lime dissolving efficiency, and provides excellent thermodynamic and kinetic conditions for dephosphorization in steel making.
At present, calcium ferrite on the market is generally prepared by burning iron concentrate powder and lime, and is expensive, so that the steelmaking cost is overhigh.
Disclosure of Invention
The invention aims to provide the red mud-based composite calcium ferrite, and the preparation method and the application thereof.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a preparation method of red mud-based composite calcium ferrite, which comprises the following steps:
mixing red mud and a calcium source, and roasting the obtained mixture in an oxygen-containing atmosphere to obtain red mud-based composite calcium ferrite; the calcium source comprises lime or calcium carbonate.
Preferably, the dosage of the red mud is Fe2O3Based on the molar content of CaO, the calcium source being used in an amount corresponding to the molar content of CaO, and the Fe2O3The mol ratio of the CaO to the CaO is 1: 0.8-1.
Preferably, the roasting temperature is 1000-1200 ℃; the heat preservation time is 0.5-2 h.
Preferably, before roasting, the method further comprises pressing the mixture into a briquette.
Preferably, Fe in the red mud2O3In an amount of>40wt％，Al2O3The content of (B) is 10-15 wt%.
Preferably, the content of the available calcium oxide in the lime is more than 80 wt%, and the content of the available calcium oxide in the calcium carbonate is more than 50 wt%.
Preferably, the oxygen-containing atmosphere includes an air atmosphere or an oxygen atmosphere.
The invention providesThe red mud-based composite calcium ferrite prepared by the preparation method comprises CaFe2O4、Ca2FeAlO5And Ca2Fe2O5。
Preferably, the red mud-based composite calcium ferrite comprises 5-15% of CaFe by mass percentage2O4、5～15％Ca2FeAlO5And 70-90% of Ca2Fe2O5。
The invention provides application of the red mud-based composite calcium ferrite in steelmaking.
The invention provides a preparation method of red mud-based composite calcium ferrite, which comprises the following steps: mixing red mud and a calcium source, and roasting the obtained mixture in an oxygen-containing atmosphere to obtain red mud-based composite calcium ferrite; the calcium source comprises lime or calcium carbonate. According to the invention, the composite calcium ferrite is prepared from the red mud which is a solid waste, the raw material cost is greatly reduced, the melting point of the prepared red mud-based composite calcium ferrite is 1050-1100 ℃, and the phase structure is mainly CaFe2O4、Ca2FeAlO5And Ca2Fe2O5Compared with the common calcium ferrite with the melting point of 1150-1250 ℃, the product has lower melting point, improves the lime dissolving efficiency by about 25 percent, and has better fluxing and dephosphorization effects when applied in the steelmaking process.
Drawings
FIG. 1 is XRD patterns of a red mud raw material used in example 1, composite calcium ferrite prepared in examples 1 to 2, and calcium ferrite prepared in comparative example 1;
FIG. 2 is a graph showing the results of the dephosphorization test in test example 1, wherein three kinds of dephosphorizing agents Fe were added respectively2O3+CaO、Fe2O3+ CaO + pure calcium ferrite and Fe2O3And the dephosphorization effect is obtained by the CaO and the composite calcium ferrite.
Detailed Description
The invention provides a preparation method of red mud-based composite calcium ferrite, which comprises the following steps:
mixing red mud and a calcium source, and roasting the obtained mixture in an oxygen-containing atmosphere to obtain red mud-based composite calcium ferrite; the calcium source comprises lime or calcium carbonate.
The red mud and the calcium source are mixed to obtain a mixture.
In the invention, the red mud is preferably industrial solid waste red mud generated in the aluminum industry production; fe in the red mud2O3Is preferably contained in>40wt％，Al2O3The content of (B) is preferably 10 to 15 wt%. Further, the chemical composition of the red mud preferably comprises Fe2O3：>40wt％，Al2O3：10～15wt％，SiO2：2～5wt％，TiO2：4～5wt％，Na2O: 1 to 2 wt%. In the invention, the water content of the red mud is preferably less than 8 wt%. The particle size of the red mud is preferably less than 200 meshes.
In the present invention, the calcium source comprises lime or calcium carbonate; the content of available calcium oxide in the lime is preferably more than 80 wt%, and the content of available calcium oxide in the calcium carbonate is preferably more than 50 wt%. In the present invention, the water content of the lime and calcium carbonate is preferably less than 1 wt%. In the present invention, the particle size of the calcium source is preferably less than 200 mesh.
The invention controls the water content of the red mud and the calcium source to be in the range, can prevent the mass ratio from being unbalanced, and simultaneously prevents the equipment from being adversely affected.
In the invention, the dosage of the red mud is Fe2O3Based on the molar content of CaO, the calcium source being used in an amount corresponding to the molar content of CaO, and the Fe2O3The molar ratio of CaO to CaO is preferably 1:0.8 to 1, more preferably 1:0.85 to 0.95, and still more preferably 1: 0.9. The invention controls Fe2O3The molar ratio of CaO to calcium ferrite (CaFe) is within the above range, and the main phase of the product is further ensured to be calcium ferrite2O4And Ca2Fe2O5) And calcium aluminoferrite (Ca)2FeAlO5)。
The present invention has no special requirement on the mixing process, and the mixing can be uniformly carried out in any manner known in the art. In the embodiment of the invention, a stirrer is adopted for mixing for 2 min.
After the mixture is obtained, the mixture is preferably pressed into a briquette, and then is roasted in an oxygen-containing atmosphere to obtain the red mud-based composite calcium ferrite.
The present invention does not require any particular way of briquetting, as is well known in the art. The invention has no special requirements on the size and shape of the agglomerate, and in the embodiment of the invention, the agglomerate is a cylindrical block pressed into D10mm XH 10 mm. The invention leads the mixture of the red mud and the calcium source to have certain strength by pressing into lumps, is convenient for sintering, and has tighter combination and better reactivity.
In the invention, the roasting temperature is preferably 1000-1200 ℃, more preferably 1050-1150 ℃, and further preferably 1100 ℃; the roasting heat preservation time is preferably 0.5-2 hours, and more preferably 1.0-1.5 hours. In the present invention, the rate of temperature rise to the temperature for the calcination is preferably 5 ℃/min. In the present invention, the oxygen-containing atmosphere is preferably an air atmosphere or an oxygen atmosphere.
In the roasting process, Fe in the red mud2O3、Al2O3React with CaO to generate CaFe2O4、Ca2FeAlO5And Ca2Fe2O5A predominant phase.
The present invention does not require special equipment for the calcination, and any high temperature heating equipment known in the art may be used. In the embodiment of the present invention, the firing is preferably performed in a horizontal high temperature resistance furnace.
After roasting, the invention preferably cools the obtained solid phase to obtain the red mud-based composite calcium ferrite.
In the process of preparing the red mud-based composite calcium ferrite, the industrial solid waste red mud is used as a preparation raw material. Red mud, Fe produced in the process of producing alumina by Bayer process2O3The content is higher. These bayer red mud are dried (moisture content)<8%) can be directly used as raw material to prepare composite calcium ferrite, and its production cost is far lower than that of general calcium ferrite product in the market.
The present invention provides the aboveThe red mud-based composite calcium ferrite prepared by the preparation method comprises CaFe2O4、Ca2FeAlO5And Ca2Fe2O5. The composite calcium ferrite preferably comprises 5-15% of CaFe by mass percentage2O4、5～15％Ca2FeAlO5And 70-90% of Ca2Fe2O5. In an embodiment of the invention, said composite calcium ferrite comprises 12% CaFe2O4、10％Ca2FeAlO5And 72% Ca2Fe2O5Or alternatively 15% CaFe2O4、10％Ca2FeAlO5And 70% Ca2Fe2O5The balance being other reactants.
The red mud-based composite calcium ferrite prepared by the invention has the main phase of CaFe2O4、Ca2FeAlO5And Ca2Fe2O5Compared with calcium ferrite, the calcium ferrite has lower melting point and higher lime dissolving efficiency, and can effectively shorten the smelting period and greatly improve the dephosphorization efficiency when used as a fluxing agent and/or a dephosphorization agent in the steelmaking process.
The invention provides application of the composite calcium ferrite in steelmaking. In the present invention, the composite calcium ferrite is preferably used as a flux and/or a dephosphorizing agent in a steel-making process. In the present invention, the steelmaking preferably includes primary refining and/or refining. The method for applying the invention has no special requirements, and the application method well known in the field can be adopted.
The composite calcium ferrite provided by the present invention, the preparation method and the application thereof are described in detail with reference to the following examples, but they should not be construed as limiting the scope of the present invention.
Example 1
a. Bayer red mud (Fe) of a certain domestic enterprise2O3：65wt％，Al2O3：12wt％，SiO2：3wt％，TiO2：4wt％，Na2O: 1.5wt percent) and lime powder are ground, and sieved by a 200-mesh sieve to obtain undersize products; according to Fe2O3The mol ratio of the red mud to CaO is 1:1, 100g of red mud and 30g of lime powder are weighed, mixed uniformly for 2min by a stirrer and pressed into cylindrical blocks D10mm XH 10 mm.
b. Putting the material blocks into a horizontal high-temperature resistance furnace, heating to 1100 ℃ at a speed of 5 ℃/min, preserving the heat for 2h in the air atmosphere, and cooling the solid phase to obtain the red mud-based composite calcium ferrite which is marked as 1100-30% CaO and comprises 12% CaFe2O4、10％Ca2FeAlO5And 72% Ca2Fe2O5。
Example 2
a. Bayer red mud (Fe) of a certain domestic enterprise2O3：65wt％，Al2O3：12wt％，SiO2：3wt％，TiO2：4wt％，Na2O: 1.5wt percent) and lime powder are ground, and sieved by a 200-mesh sieve to obtain undersize products; according to Fe2O3The mol ratio of the red mud to CaO is 1:0.8, 100g of red mud and 25g of lime powder are weighed and mixed uniformly by a stirrer for 2min, and then the mixture is directly put into a crucible without briquetting.
b. Putting the crucible into a horizontal high-temperature resistance furnace, heating to 1100 ℃ at the speed of 5 ℃/min, preserving the heat for 2h in the air atmosphere, and cooling the solid phase to obtain the red mud-based composite calcium ferrite which is marked as 1100-25% CaO and comprises 15% CaFe2O4、10％Ca2FeAlO5And 70% Ca2Fe2O5。
Comparative example 1
Using pure Fe2O3And CaO to prepare calcium ferrite, wherein the preparation steps are as follows:
74.1g of Fe2O3Stirring with 25.9g CaO powder for 2min, pressing into cylindrical block D10mm XH 10mm, heating to 1200 deg.c at 5 deg.c/min in a horizontal high temperature resistance furnace, maintaining in air atmosphere for 2 hr, cooling the solid phase to obtain calcium ferrite of 1200 deg.c, including 25% CaFe2O4、75％Ca2Fe2O5。
Structural characterization:
for example 1XRD characterization is carried out on the red mud raw material, the red mud-based composite calcium ferrite prepared in the embodiments 1-2 and the calcium ferrite prepared in the comparative example 1, and the result is shown in figure 1. As can be seen from FIG. 1, compared with the raw material and pure calcium ferrite, the invention utilizes the similar phase of calcium ferrite in the product calcined by red mud and lime, and Ca is also contained2FeAlO5Phase, absence of unreacted Fe2O3。
Test example 1
Taking an initial value [ P]The content of [ C ] is 0.20 to 0.25 wt%]Content 4.0 wt%, [ Si ]]Carrying out dephosphorization test on the pig iron blocks with the content of 0.4 wt%, at the temperature of 1410 ℃, and respectively adding Fe into three groups2O3+CaO、Fe2O3+ CaO + pure calcium ferrite, Fe2O3+ CaO + the red mud-based composite calcium ferrite of example 1. Wherein the initial Fe contained in the three groups is controlled2O3Consistent with the total content of CaO. In particular, a dephosphorizing agent Fe2O3The CaO accounts for 20 percent of the mass of the molten iron, wherein the Fe2O3The content of (2) is 85%, and the content of CaO is 15%; fe2O3The total addition of the + CaO + pure calcium ferrite accounts for 20 percent of the mass of the molten iron, wherein Fe2O3The content of (A) is 67%, the content of CaO is 8.4%, and the content of pure calcium ferrite is 24.6%; fe2O3+ CaO + example 1 the amount of added red mud-based composite calcium ferrite was 20% by mass of the molten iron, wherein Fe2O3The content of the red mud base composite calcium ferrite is 66.5 percent, the content of CaO is 7.8 percent, and the content of the red mud base composite calcium ferrite in the example 1 is 25.7 percent; taking the iron water sample after reaction for 0min, 5min and 10min, and measuring the molten iron [ P ]]Content, compared with dephosphorization effects under three different conditions. The results are shown in FIG. 2.
As can be seen from FIG. 2, under high phosphorus conditions, the first type of Fe2O3+ CaO represents the most common dephosphorization method for steel making at present, and the end point [ P ] is within 10min]The content was 0.123 wt%. The second type adds part of pure calcium ferrite, the adding quantity is controlled to be 25%, the end point [ P ] is within 10min]The content of 0.0995 wt% has better dephosphorization effect than the first type. The third type of addition uses the composite calcium ferrite prepared in example 1, the end point [ P ] is within 10min]The content is 0.0215 wt%, and the dephosphorization effect is superior to the former two types. To sum up, the present invention is adoptedThe red mud-based composite calcium ferrite prepared by the method has high dephosphorization efficiency and excellent effect.
Test example 2
The test was performed with reference to the procedure of Performance test 1, taking the initial [ P ]]The content of [ C ] is 0.20 to 0.25 wt%]Content 4.0 wt%, [ Si ]]Dephosphorization test was carried out on the pig iron blocks with a content of 0.4 wt.%, at 1410 ℃ with addition of Fe2O3+ CaO + the red mud-based composite calcium ferrite of example 2. Wherein the addition amount of the dephosphorizing agent accounts for 20 percent of the mass of the molten iron, wherein Fe2O3The content of the red mud-based composite calcium ferrite is 66.5 percent, the content of CaO is 8.5 percent, the content of the red mud-based composite calcium ferrite in the example 2 is 25 percent, an iron water sample is taken after the reaction is carried out for 10min, and the iron water [ P ] is measured]Content, [ P ]]The content reaches the qualified level and is 0.032 wt%.
The embodiment and the comparative example show that the invention provides the preparation method and the application of the composite calcium ferrite, and the composite calcium ferrite prepared by the invention has low cost and better fluxing and dephosphorization effects in the steelmaking process.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.