High aluminum slag composition and blast furnace smelting method of high-Al2O3 ore

Abstract

The invention relates to a high aluminum slag composition and a blast furnace smelting method of high Al2O3 ore. The high aluminum slag composition comprises Al2O3, MgO, CaO and SiO2. The quaternary alkalinity R4 of the high aluminum slag composition is 0.90 to 1.10; the mass ratio of the MgO to the Al2O3 is (0.4-0.9): 1; the quaternary alkalinity of the high-aluminum slag composition and the mass ratio of MgO to Al2O3 are synergistically and dynamically regulated and controlled to be within a specific range, and the fluxing agent and the rare earth enhancer are matched for combined action, so that the flowability and desulfurization capacity of the blast furnace smelting slag are improved, the slag viscosity is preferably as low as 2.60 Pa.s or below, the sulfur distribution coefficient is preferably improved to 36 or above, meanwhile, the energy consumption is reduced, and the production cost is reduced. The melting point of the slag is as low as 1400 DEG C or below, and the fuel ratio per ton of iron is as low as 512 Kg / t or below.

Description

Technical Field

[0001] The invention relates to the technical field of iron and steel metallurgy, and in particular to a high-aluminum slag composition and a blast furnace smelting method of a high-Al2O3 ore. Background Art

[0002] In recent years, it has become a trend to add a large amount of high-aluminum low-priced ore to blast furnaces. However, when a blast furnace uses a large amount of high-aluminum ore, it will cause the slag viscosity to increase, the blast furnace slag and iron tapping to be difficult, and increase fuel consumption. Therefore, in order to make full use of high-aluminum ore and effectively reduce the production cost of blast furnaces, high-aluminum ore is basically used in conjunction with a large amount of low-aluminum ore, and the Al2O3 content in the blast furnace slag is ultimately controlled below 16%. However, this method of using high-aluminum ore to dilute the "Al2O3 content in slag" limits the large-scale use of high-aluminum ore, and it is difficult to significantly reduce the production cost of blast furnaces. Based on this, researchers have continuously proposed new methods for using a large proportion of high-aluminum ore to meet the requirements of various steel mills to reduce the production cost of blast furnaces.

[0003] For example, CN108315516A discloses an ultra-high aluminum slag system for blast furnace smelting, the mass percentage of its components is: MgO 10-16%; Al2O3 18-30%; TiO2 1-5%; R2 0.7-1.15. The ultra-high aluminum slag system is still adjusted based on the binary basicity R2 (CaO / SiO2). However, high Al2O3 will lead to increased slag viscosity, and simply increasing CaO / SiO2 will sacrifice desulfurization capacity (excessive CaO leads to a decrease in free CaO in the slag); in addition, the imbalance of the magnesium-aluminum ratio leads to the inability of MgO in the high aluminum slag to fully exert its viscosity-reducing effect.

[0004] CN102251064A discloses a method for improving the fluidity of high-aluminum slag in a blast furnace ironmaking process, comprising the following steps: in the blast furnace ironmaking process, part of the iron ore powder is replaced by boron-containing iron concentrate, 8-27% by mass of boron-containing iron concentrate containing Fe≥50% and B2O3≤10%, 8-15% of flux, 2.5-4.5% of fuel and 53-82% of iron ore powder are made into a mixture, which is transported to a sintering machine for sintering to obtain a boron-containing sintered ore. However, this method has a poor effect on reducing the viscosity of the slag, and the desulfurization capacity still has a large room for improvement. Moreover, B2O3 in the iron ore cannot enter the slag 100%, and a part of the B2O3 is reduced to B and enters the slag, which will affect the subsequent production of special steel.

[0005] Based on this, how to provide a new high-aluminum slag composition and a blast furnace smelting method for high Al2O3 ore, reduce the slag viscosity and melting point, improve the desulfurization capacity and reduce the fluctuation rate of furnace conditions are technical problems that need to be solved urgently in this field. Summary of the invention

[0006] To solve the above technical problems, the present invention provides a high-alumina slag composition and a blast furnace smelting method for high-Al₂O₃ ore, which solves the problems of high slag viscosity, high melting point, large fuel consumption, and low desulfurization efficiency during the smelting of the existing high-alumina slag composition.

[0007] To achieve this purpose, the present invention adopts the following technical solutions:

[0008] In the first aspect, the present invention provides a high-alumina slag composition, which includes Al₂O₃, MgO, CaO, and SiO₂; the quaternary basicity R4 of the high-alumina slag composition is 0.90 - 1.10;

[0009] The mass ratio of MgO to Al₂O₃ is (0.4 - 0.9):1.

[0010] Wherein, the quaternary basicity is the ratio of the sum of the masses of CaO and MgO to the sum of the masses of Al₂O₃ and SiO₂ in the high-alumina slag composition.

[0011] The quaternary basicity R4 is 0.90 - 1.10, for example, it can be 0.90, 0.92, 0.94, 0.96, 0.98, 1.0, or 1.1, etc.

[0012] The mass ratio of MgO to Al₂O₃ is (0.4 - 0.9):1, for example, it can be 0.4:1, 0.45:1, 0.5:1, 0.55:1, 0.6:1, 0.65:1, 0.7:1, 0.75:1, 0.8:1, 0.85:1, or 0.9:1, etc.

[0013] By synergistically and dynamically regulating the quaternary basicity of the high-alumina slag composition and the mass ratio of MgO to Al₂O₃ within a specific range, compared with the traditional method of simply increasing CaO / SiO₂ and only passively supplementing MgO, the present invention not only solves the problem of magnesium-aluminum ratio imbalance, enables MgO to fully play the role of viscosity reduction, but also ensures sufficient free CaO in the slag, improves the desulfurization ability, and additionally reduces the melting point of the slag and the consumption of fuel.

[0014] Preferably, the mass content of Al₂O₃ in the high-alumina slag composition is 18 - 22 wt%, for example, it can be 18 wt%, 19 wt%, 20 wt%, 21 wt%, or 22 wt%, etc.

[0015] Preferably, the mass ratio of CaO to MgO in the high-alumina slag composition is (1.5 - 3):1, for example, it can be 1.5:1, 1.8:1, 2:1, 2.2:1, 2.5:1, 2.8:1, or 3:1.

[0016] Preferably, the quaternary basicity R4 of the high-alumina slag composition is 0.95 to 1.05, and can be, for example, 0.95, 0.96, 0.97, 0.98, 0.99, 1.0, 1.01, 1.02, 1.03, 1.04 or 1.05, etc.

[0017] Preferably, the mass ratio of MgO to Al2O3 is (0.5 to 0.8):1, and can be, for example, 0.5:1, 0.55:1, 0.6:1, 0.65:1, 0.7:1, 0.75:1 or 0.8:1, etc.

[0018] The present invention further preferably has the quaternary basicity R4 of the high-alumina slag composition being 0.95 to 1.05, and the mass ratio of MgO to Al2O3 being (0.5 to 0.8):1. By giving full play to the synergistic regulation effect, it can further reduce the viscosity and melting point of the obtained slag, further improve the desulfurization ability, and further reduce the furnace condition volatility. Preferably, the high-alumina slag composition further includes a flux.

[0019] Preferably, the mass content of the flux in the high-alumina slag composition is 0.5 to 1.0 wt%, and can be, for example, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt% or 1.0 wt%, etc.

[0020] Preferably, the flux includes borax and / or fluorite, and is preferably borax.

[0021] In the high-alumina slag composition of the present invention, by further adding a flux, and preferably adding borax (Na2B4O7·10H2O), the depolymerization of the silicate network is promoted by the breaking of B-O bonds, and low-melting-point compounds are formed with other components in the slag, reducing the melting point of the slag. At the same time, borax can form stable compounds with sulfur in the slag, thereby enhancing the desulfurization ability of the slag, and adding borax can further improve the fluidity of the slag.

[0022] Preferably, the high-alumina slag composition further includes a rare earth strengthening agent.

[0023] Preferably, the mass content of the rare earth strengthening agent in the high-alumina slag composition is 0.1 to 0.4 wt%, and can be, for example, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.35 wt% or 0.4 wt%, etc.

[0024] Preferably, the rare earth strengthening agent includes any one or a combination of at least two of La2O3, CeO2, Nd2O3 or Y2O3. Typical but non-limiting combinations include the combination of La2O3 and CeO2, the combination of La2O3 and Y2O3, the combination of CeO2 and Y2O3, or the combination of Nd2O3 or Y2O3, etc.

[0025] In the high-alumina slag composition of the present invention, by further adding a rare earth strengthening agent and utilizing the affinity of rare earth elements in the rare earth strengthening agent for sulfur in the slag, the desulfurization ability of the slag is improved.

[0026] In a second aspect, the present invention provides a blast furnace smelting method for high-Al2O3 ore, and the blast furnace smelting method includes the following steps:

[0027] Mix high-Al2O3 ore, a magnesium source flux, a calcium source flux, and a silicon source flux to obtain a high-alumina slag composition and carry out smelting, and the quaternary basicity R4 of the high-alumina slag composition is 0.90-1.10, and the mass ratio of MgO to Al2O3 in the high-alumina slag composition is (0.4-0.9):1.

[0028] Among them, the quaternary basicity R4 of the high-alumina slag composition is 0.90-1.10, and for example, it can be 0.90, 0.92, 0.94, 0.96, 0.98, 1.0 or 1.1, etc.

[0029] The mass ratio of MgO to Al2O3 in the high-alumina slag composition is (0.4-0.9):1, and for example, it can be 0.4:1, 0.45:1, 0.5:1, 0.55:1, 0.6:1, 0.65:1, 0.7:1, 0.75:1, 0.8:1, 0.85:1 or 0.9:1, etc.

[0030] In the blast furnace smelting method for high-Al2O3 ore of the present invention, by synergistically optimizing the quaternary basicity of the high-alumina slag system and the mass ratio of MgO to Al2O3 within a specific range during the smelting process, the fluidity of the smelted slag is enhanced, the melting point is reduced, the desulfurization ability is improved, and the energy consumption is reduced; moreover, the stability of the smelting is improved, and the furnace condition volatility is reduced.

[0031] It should be noted that if the contents of SiO2 and CaO in the magnesium source flux are sufficient to ensure that the mass ratio of MgO to Al2O3 and its quaternary basicity in the high-alumina slag composition are within the above corresponding ranges, there is no need to additionally add a calcium source flux and a silicon source flux.

[0032] The blast furnace smelting method for high-Al2O3 ore in the second aspect of the present invention can be carried out by using the high-alumina slag composition described in the first aspect.

[0033] Preferably, the mass content of Al2O3 in the high-Al2O3 ore is 18-22 wt%, and for example, it can be 18 wt%, 18.5 wt%, 19 wt%, 19.5 wt%, 20 wt%, 20.5 wt%, 21 wt%, 21.5 wt% or 22 wt%, etc.

[0034] Preferably, the quaternary basicity R4 of the high-alumina slag composition is 0.95 to 1.05, and may be, for example, 0.95, 0.96, 0.97, 0.98, 0.99, 1.0, 1.01, 1.02, 1.03, 1.04, or 1.05, etc.

[0035] Preferably, the mass ratio of MgO to Al2O3 in the high-alumina slag composition is (0.5 to 0.8):1, and may be, for example, 0.5:1, 0.55:1, 0.6:1, 0.65:1, 0.7:1, 0.75:1, or 0.8:1, etc.

[0036] Preferably, the mass ratio of CaO to MgO in the high-alumina slag composition is (1.5 to 3):1, and may be, for example, 1.5:1, 1.8:1, 2:1, 2.2:1, 2.5:1, 2.8:1, or 3:1, etc.

[0037] Preferably, the magnesium source flux includes calcined dolomite.

[0038] Preferably, the content of MgO in the calcined dolomite is 30wt% to 35wt%, and may be, for example, 30wt%, 31wt%, 32wt%, 33wt%, 34wt%, or 35wt%, etc.

[0039] Preferably, the calcined dolomite includes dolomite with a roasting temperature of 700 to 900°C, and may be, for example, 700°C, 750°C, 800°C, 850°C, or 900°C, etc.

[0040] The present invention further preferably uses dolomite with a roasting temperature of 700 to 900°C as the magnesium source flux, which reduces the melting point of the slag compared with ordinary dolomite.

[0041] Preferably, the magnesium source solvent further includes calcined magnesite and / or calcined serpentine.

[0042] Preferably, the calcined magnesite includes magnesite with a roasting temperature of 600 to 700°C, and may be, for example, 600°C, 620°C, 650°C, 680°C, or 700°C, etc.

[0043] Preferably, the content of MgO in the magnesite is 45wt% to 50wt%, and may be, for example, 45wt%, 46wt%, 47wt%, 48wt%, 49wt%, or 50wt%, etc.

[0044] Preferably, the calcined serpentine includes serpentine with a roasting temperature of 500 to 700°C, and may be, for example, 500°C, 550°C, 600°C, 650°C, or 700°C, etc.

[0045] Preferably, the light-burned serpentine contains 30-35 wt% of MgO, such as 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, etc.

[0046] Preferably, the calcium source flux includes any one or at least two combinations of limestone, dolomite or quicklime, and typical but non-limiting combinations include the combination of limestone and dolomite, the combination of limestone and quicklime, or the combination of dolomite and quicklime, etc.

[0047] Preferably, the mass content of CaO in the calcium source flux is 40-90 wt%, such as 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt% or 90 wt%, etc.

[0048] Preferably, the silicon source flux includes silica and / or quartz sand.

[0049] Preferably, the mass content of SiO2 in the silicon source flux is 20-99 wt%, such as 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, 90 wt% or 99 wt%, etc.

[0050] Preferably, the mixing also includes adding a flux and / or a rare earth strengthening agent, preferably a flux and a rare earth strengthening agent.

[0051] Preferably, the addition amount of the flux is 0.5-1.0 wt%, such as 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt% or 1.0 wt%, etc.

[0052] Preferably, the flux includes borax and / or fluorite.

[0053] Preferably, the rare earth strengthening agent includes any one or at least two combinations of La2O3, CeO2, Nd2O3 or Y2O3, and typical but non-limiting combinations include the combination of La2O3 and CeO2, the combination of La2O3 and Y2O3, the combination of CeO2 and Nd2O3, or the combination of Nd2O3 and Y2O3, etc.

[0054] Preferably, the smelting temperature is 1400-1600 °C, such as 1400 °C, 1450 °C, 1500 °C, 1550 °C or 1600 °C, etc.

[0055] Preferably, the smelting time is 2-4 h, such as 2 h, 2.5 h, 3 h, 3.5 h or 4 h, etc.

[0056] Compared with the prior art, the present invention has at least the following beneficial effects:

[0057] (1) The high-alumina slag composition provided by the present invention, by synergistically and dynamically regulating the quaternary basicity of the high-alumina slag composition and the mass ratio of MgO and Al2O3 within a specific range, in combination with a flux and a rare-earth strengthening agent, jointly act to improve the fluidity of the blast furnace smelting slag. The slag viscosity is preferably as low as below 2.60 Pa·s, and the slag melting point drop is preferably as low as below 1400 °C, thereby reducing energy consumption. The fuel ratio per ton of iron is preferably reduced to below 512 Kg / t, and the desulfurization ability is improved. The sulfur distribution coefficient is preferably increased to above 36.

[0058] (2) The blast furnace smelting method of high-Al2O3 ore provided by the present invention, by adding the types of blast furnace fluxes, quaternary basicity and component ratios, using lightly burned dolomite instead of ordinary dolomite, adding a flux and a rare-earth strengthening agent, etc., makes the obtained slag have significantly improved viscosity, melting point and desulfurization efficiency compared with the slag obtained by the traditional method of only regulating the binary basicity, and significantly reduces the furnace condition volatility. Specific embodiments

[0059] To facilitate the understanding of the present invention, the following examples are listed. Those skilled in the art should understand that the examples are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0060] I. Examples

[0061] Example 1

[0062] This example provides a high-alumina slag composition, which includes 20 wt% Al2O3, 12 wt% MgO, 36 wt% CaO, 27 wt% SiO2, 0.8 wt% borax (Na2B4O7·10H2O) and 0.2 wt% La2O3 in the high-alumina slag composition, and the rest is Fe2O3 and other impurities;

[0063] That is, the quaternary basicity R4 of the high-alumina slag composition is 1.02; the mass ratio of MgO and Al2O3 is 0.6:1, and the mass ratio of CaO and MgO is 3:1.

[0064] This example provides a blast furnace smelting method of high-Al2O3 ore, and the blast furnace smelting method includes the following steps:

[0065] Mix high-Al2O3 ore (20 wt% Al2O3), lightly burned dolomite (calcination temperature of 800 °C, MgO content of 32 wt%), and lightly burned magnesite (calcination temperature of 600 °C, MgO content of 48 wt%) until the mass ratio of MgO to Al2O3 in the resulting high-aluminum slag composition is 0.6:1, the mass ratio of CaO to MgO is 3:1, and the quaternary basicity R4 is 1.02; and add 0.8 wt% borax (Na2B4O7·10H2O) and 0.2 wt% La2O3, and smelt for 3 h at 1500 °C to obtain the slag.

[0066] Example 2

[0067] This example provides a high-aluminum slag composition, which includes 18 wt% Al2O3, 9 wt% MgO, 22.5 wt% CaO, 15.2 wt% SiO2, 0.5 wt% borax (Na2B4O7·10H2O), and 0.1 wt% La2O3, and the rest is Fe2O3 and other impurities;

[0068] That is, the quaternary basicity R4 of the high-aluminum slag composition is 0.95; the mass ratio of MgO to Al2O3 is 0.5:1, and the mass ratio of CaO to MgO is 2.5:1.

[0069] This example provides a blast furnace smelting method for high-Al2O3 ore, and the blast furnace smelting method includes the following steps:

[0070] Mix high-Al2O3 ore (18 wt% Al2O3), lightly burned dolomite (calcination temperature of 700 °C, MgO content of 30 wt%), and lightly burned magnesite (calcination temperature of 600 °C, MgO content of 45 wt%) until the mass ratio of MgO to Al2O3 in the resulting high-aluminum slag composition is 0.5:1, the mass ratio of CaO to MgO is 2.5:1, and the quaternary basicity R4 is 0.95; and add 0.5 wt% borax (Na2B4O7·10H2O) and 0.1 wt% La2O3, and smelt for 2.5 h at 1450 °C to obtain the slag.

[0071] Example 3

[0072] This example provides a high-aluminum slag composition, which includes 22 wt% Al2O3, 17.6 wt% MgO, 26.4 wt% CaO, 19.9 wt% SiO2, 1.0 wt% borax (Na2B4O7·10H2O), and 0.4 wt% CeO2, and the rest is Fe2O3 and other impurities;

[0073] That is, the quaternary basicity R4 of the high-alumina slag composition is 1.05; the mass ratio of MgO to Al2O3 is 0.8:1, and the mass ratio of CaO to MgO is 1.5:1.

[0074] This embodiment provides a blast furnace smelting method for high-Al2O3 ore. The blast furnace smelting method includes the following steps:

[0075] Mix high-Al2O3 ore (22 wt% Al2O3), lightly burned dolomite (calcination temperature of 900 °C, MgO content of 35 wt%), and lightly burned serpentine (Mg3Si2O5(OH)4, calcination temperature of 600 °C, MgO content of 32 wt%) until the mass ratio of MgO to Al2O3 in the obtained high-alumina slag composition is 0.8:1, the mass ratio of CaO to MgO is 1.5:1, and the quaternary basicity R4 is 1.05; and add 1.0 wt% borax (Na2B4O7·10H2O) and 0.4 wt% CeO2, and smelt at 1550 °C for 3.5 h to obtain slag.

[0076] Example 4

[0077] This embodiment provides a high-alumina slag composition. Except that the quaternary basicity R4 of the high-alumina slag composition is 0.90, the mass ratio of MgO to Al2O3 is 0.4:1, and the flux addition amount in the blast furnace smelting method of the high-Al2O3 ore is correspondingly changed, the rest are the same as in Example 1.

[0078] Example 5

[0079] This embodiment provides a high-alumina slag composition. Except that the quaternary basicity R4 of the high-alumina slag composition is 1.10, the mass ratio of MgO to Al2O3 is 0.9:1, and the flux addition amount in the blast furnace smelting method of the high-Al2O3 ore is correspondingly changed, the rest are the same as in Example 1.

[0080] Example 6

[0081] This embodiment provides a high-alumina slag composition. No borax (Na2B4O7·10H2O) is added to the high-alumina slag composition. Except that the blast furnace smelting method of the high-Al2O3 ore is correspondingly changed, the rest are the same as in Example 1.

[0082] Example 7

[0083] This embodiment provides a high-alumina slag composition. No La2O3 is added to the high-alumina slag composition. Except that the blast furnace smelting method of the high-Al2O3 ore is correspondingly changed, the rest are the same as in Example 1.

[0084] Example 8

[0085] This embodiment provides a high-aluminum slag composition. The mass content of La2O3 in the high-aluminum slag composition is 0.5 wt%, and except for the corresponding change in the blast furnace smelting method of the high Al2O3 ore, the rest are the same as in Embodiment 1.

[0086] Example 9

[0087] This embodiment provides a blast furnace smelting method for high Al2O3 ore. Except that the calcined dolomite with a roasting temperature of 800 °C is replaced by ordinary dolomite, the rest are the same as in Embodiment 1.

[0088] II. Comparative Examples

[0089] Comparative Example 1

[0090] This comparative example provides a high-aluminum slag composition. Except that the quaternary basicity R4 of the high-aluminum slag composition is 1.02, but the mass ratio of MgO to Al2O3 is 0.3:1, and the flux addition amount in the blast furnace smelting method of the high Al2O3 ore is correspondingly changed, the rest are the same as in Embodiment 1.

[0091] Comparative Example 2

[0092] This comparative example provides a high-aluminum slag composition. Except that the quaternary basicity R4 of the high-aluminum slag composition is 0.8, but the mass ratio of MgO to Al2O3 is 0.6:1, and the flux addition amount in the blast furnace smelting method of the high Al2O3 ore is correspondingly changed, the rest are the same as in Embodiment 1.

[0093] Comparative Example 3

[0094] This comparative example provides a high-aluminum slag composition. Except that the quaternary basicity R4 of the high-aluminum slag composition is 0.8, but the mass ratio of MgO to Al2O3 is 0.3:1, and the flux addition amount in the blast furnace smelting method of the high Al2O3 ore is correspondingly changed, the rest are the same as in Embodiment 1.

[0095] Comparative Example 4

[0096] This comparative example provides a high-aluminum slag composition. Except that the quaternary basicity R4 of the high-aluminum slag composition is 1.2, but the mass ratio of MgO to Al2O3 is 1:1, and the flux addition amount in the blast furnace smelting method of the high Al2O3 ore is correspondingly changed, the rest are the same as in Embodiment 1.

[0097] Comparative Example 5

[0098] This comparative example provides a blast furnace smelting method for high Al2O3 ore, and the high-aluminum smelting method is carried out by the method disclosed in CN115449574B.

[0099] In this comparative example, only the binary basicity and ternary basicity of the high-alumina slag composition were controlled, and it was impossible to fully coordinate high basicity and high fluidity, resulting in poor smelting effects.

[0100] III. Tests and Results

[0101] The viscosities, melting points, sulfur partition coefficients, and fuel ratios per ton of iron of the slag obtained by the blast furnace smelting method of the high-Al2O3 ore provided in the above examples or comparative examples were tested, and the results are shown in Table 1;

[0102] Table 1

[0103]

[0104]

[0105] Note: "-" in Table 1 indicates no relevant data.

[0106] It can be seen from the data in Table 1 that:

[0107] (1) By comprehensively considering Examples 1 to 3, it can be seen that for the high-alumina slag composition and the blast furnace smelting method of high-Al2O3 ore provided by the present invention, by coordinately and dynamically regulating the quaternary basicity of the high-alumina slag composition and the mass ratio of MgO to Al2O3, the viscosity of the obtained slag is reduced to below 2.60 Pa·s, the melting point of the slag is reduced to below 1400 °C, the sulfur partition coefficient is increased to above 36, and the fuel ratio per ton of iron is reduced to below 512 Kg / t, effectively avoiding the defects of the slag after blast furnace smelting of the existing high-alumina slag composition.

[0108] (2) By comprehensively considering Example 1 and Examples 4 and 5, it can be seen that in Example 4, both the quaternary basicity R4 and the mass ratio of MgO to Al2O3 in the high-alumina slag composition are slightly lower, resulting in an increase in the viscosity, melting point, and fuel ratio per ton of iron of the slag, and a decrease in the sulfur partition coefficient; in Example 5, both the quaternary basicity R4 and the mass ratio of MgO to Al2O3 in the high-alumina slag composition are slightly higher, also resulting in an increase in the viscosity, melting point, and fuel ratio per ton of iron of the slag, and a decrease in the sulfur partition coefficient; thus, it is shown that the present invention further preferably sets the quaternary basicity R4 of the high-alumina slag composition to be 0.95 - 1.05, and further preferably sets the mass ratio of MgO to Al2O3 to be (0.5 - 0.8):1, further reducing the viscosity, melting point, and energy consumption of the obtained slag, and simultaneously further improving the desulfurization ability.

[0109] (3) From a comprehensive comparison of Example 1 with Examples 6 to 9, it can be seen that in Example 6, no borax was added to the high-alumina slag composition, resulting in an increase in slag viscosity, an increase in melting point, a decrease in sulfur distribution coefficient, and an increase in fuel ratio per ton of iron. Whether La2O3 was not added to the high-alumina slag composition as described in Example 7 or the mass content of La2O3 added to the high-alumina slag composition in Example 8 was too high, both led to an increase in slag viscosity, an increase in melting point, a decrease in sulfur distribution coefficient, and an increase in fuel ratio per ton of iron. This is because rare earth strengtheners can improve the desulfurization ability by utilizing the affinity of rare earth elements for sulfur in the slag, but inappropriate addition amounts will affect the effect. In Example 9, the ordinary dolomite was used in the blast furnace smelting method, resulting in an increase in slag viscosity, an increase in melting point, a decrease in sulfur distribution coefficient, and an increase in fuel ratio per ton of iron, because calcined dolomite can reduce the melting point of the slag compared with ordinary dolomite. Thus, it is shown that the present invention further preferably adds a flux to the high-alumina slag composition, or further preferably adds a rare earth strengthener, and more preferably the mass content of the rare earth strengthener in the high-alumina slag composition is 0.1 - 0.4 wt%; or preferably uses calcined dolomite as the magnesium source flux; all of which further ensure low furnace condition volatility, reduce the melting point and viscosity of the slag, improve the desulfurization ability, and reduce energy consumption.

[0110] (4) From a comprehensive comparison of Example 1 with Comparative Examples 1 to 5, it can be seen that since the quaternary basicity of the high-alumina slag composition and the mass ratio of MgO and Al2O3 were not synergistically regulated within a suitable range in Comparative Examples 1 to 4, the fluidity of the slag was still poor, the melting point was high, efficient desulfurization could not be achieved, and the energy consumption was still high. In Comparative Example 5, only the binary basicity and ternary basicity of the high-alumina slag composition were controlled, and the high basicity and high fluidity could not be fully coordinated, resulting in poor smelting effects.

[0111] In summary, the present invention synergistically and dynamically regulates the quaternary basicity of the high-alumina slag composition and the mass ratio of MgO and Al2O3 within a specific range, and combines with a flux and a rare earth strengthener to jointly improve the smelting effect of blast furnace smelting, improve the fluidity and desulfurization ability of the slag, reduce the melting point of the slag and the fuel ratio per ton of iron, that is, reduce the energy consumption.

[0112] The applicant declares that the above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and public scope of the present invention.

Claims

1. A high-alumina slag composition, characterized in that, The high-alumina slag composition includes Al2O3, MgO, CaO, and SiO2; the quaternary basicity R4 of the high-alumina slag composition is 0.90 to 1.10; The mass ratio of MgO to Al2O3 is (0.4 to 0.9):

1.

2. The high-alumina slag composition according to claim 1, characterized in that, The mass content of Al2O3 in the high-alumina slag composition is 18 to 22 wt%. Preferably, the mass ratio of CaO to MgO in the high-alumina slag composition is (1.5 to 3):

1.

3. The high-alumina slag composition according to claim 1 or 2, characterized in that, The quaternary basicity R4 of the high-alumina slag composition is 0.95 to 1.05; Preferably, the mass ratio of MgO to Al2O3 is (0.5 to 0.8):

1.

4. The high-alumina slag composition according to any one of claims 1 to 3, characterized in that, The high-alumina slag composition further includes a flux; Preferably, the mass content of the flux in the high-alumina slag composition is 0.5 to 1.0 wt%; Preferably, the flux includes borax and / or fluorite, preferably borax.

5. The high-alumina slag composition according to any one of claims 1 to 4, characterized in that, The high-alumina slag composition further includes a rare-earth strengthening agent; Preferably, the mass content of the rare-earth strengthening agent in the high-alumina slag composition is 0.1 to 0.4 wt%; Preferably, the rare-earth strengthening agent includes any one or a combination of at least two of La2O3, CeO2, Nd2O3, or Y2O3.

6. A blast furnace smelting method for high-Al2O3 ore, characterized in that, The blast furnace smelting method includes the following steps: Mixing high-Al2O3 ore, a magnesium source flux, a calcium source flux, and a silicon source flux to obtain a high-alumina slag composition and conducting smelting, and the quaternary basicity of the high-alumina slag composition is R4 of 0.90 to 1.10, and the mass ratio of MgO to Al2O3 in the high-alumina slag composition is (0.4 to 0.9):

1.

7. The blast furnace smelting method according to claim 6, characterized in that The mass content of Al2O3 in the high-Al2O3 ore is 18 to 22 wt%; Preferably, the quaternary basicity of the high-alumina slag composition is R4 of 0.95 to 1.05; Preferably, the mass ratio of MgO to Al2O3 in the high-alumina slag composition is (0.5 to 0.8):1; Preferably, the mass ratio of CaO to MgO in the high-alumina slag composition is (1.5 to 3):

1.

8. The blast furnace smelting method according to claim 6 or 7, characterized in that, The magnesium source flux includes light-burned dolomite; Preferably, the content of MgO in the light-burned dolomite is 30 wt% to 35 wt%; Preferably, the light-burned dolomite includes dolomite with a roasting temperature of 700 to 900 °C; Preferably, the magnesium source solvent further includes light-burned magnesite and / or light-burned serpentine; Preferably, the light-burned magnesite includes magnesite with a roasting temperature of 600 to 700 °C; Preferably, the content of MgO in the light-burned magnesite is 45 wt% to 50 wt%; Preferably, the light-burned serpentine includes serpentine with a roasting temperature of 500 to 700 °C; Preferably, the content of MgO in the light-burned serpentine is 30 wt% to 35 wt%.

9. The blast furnace smelting method according to any one of claims 6 to 8, characterized in that The calcium source flux includes any one or a combination of at least two of limestone, dolomite, or quicklime; Preferably, the mass content of CaO in the calcium source flux is 40 to 90 wt%; Preferably, the silicon source flux includes silica and / or quartz sand; Preferably, the mass content of SiO2 in the silicon source flux is 20 to 99 wt%; Preferably, the mixing further includes adding a flux and / or a rare earth strengthening agent, preferably a flux and a rare earth strengthening agent; Preferably, the addition amount of the flux is 0.5-1.0 wt%; Preferably, the flux includes borax and / or fluorite; Preferably, the addition amount of the rare earth strengthening agent is 0.1-0.4 wt%; Preferably, the rare earth strengthening agent includes any one or a combination of at least two of La2O3, CeO2, Nd2O3 or Y2O3.

10. The blast furnace smelting method according to any one of claims 6 to 9, characterized in that, The temperature of the smelting is 1400-1600 °C; Preferably, the time of the smelting is 2-4 h.

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