Method for preparing low-alkalinity iron ore by using ladle

Abstract

The invention provides a method for preparing low-alkalinity iron ore through a ladle, and belongs to the field of smelting. The method comprises the steps that first molten iron with set quality parameters is obtained; mixing the low-alkalinity iron ore with lime to obtain a mixed material with set alkalinity; a ladle is filled with the first molten iron, the mixed material is added in the filling process, and a ladle containing second molten iron is obtained; and the second molten iron in the ladle is stirred. Stable feeding of the low-alkalinity iron ore in the ladle is realized by controlling the molten iron condition, the feeding system and the stirring process; the molten top slag performance of the ladle is controlled by blending the mixed material with the set alkalinity, and slag overflow control over the ladle under the low-alkalinity iron ore blending condition is achieved.

Description

Technical Field

[0001] The present application relates to the field of smelting technology, and in particular to a method for utilizing a molten iron ladle to prepare low-basicity iron ore. Background Art

[0002] Iron ore is the basic raw material for steel manufacturing in the blast furnace-converter long process. It is prepared into sintered ore or pelletized ore through sintering or pelletizing process and used as raw material for blast furnace ironmaking. Due to the limitations of iron grade in iron ore and blast furnace smelting process, domestic steel mills generally use sintered ore as the main raw material for blast furnace ironmaking, and its proportion is generally ≥80%. The storage capacity of iron ore with basicity <1 is large, but due to the low basicity, a large amount of flux (such as lime) needs to be added when preparing sintered ore (basicity of about 2), and the consumption of a large amount of flux not only increases production costs and energy consumption, but also increases carbon emissions per ton of iron.

[0003] In response to the above problems, the pre-iron process generally prepares sintered ore or directly prepares pelletized ore by reducing the proportion of low-basicity iron ore. However, both of the above methods have the problem of low utilization rate of low-basicity iron ore, which is not conducive to the sustainable development of steel enterprises. In addition, some steel enterprises use low-basicity iron ore in the converter to achieve the purpose of resource utilization. The advantage of this process is that the iron ore does not undergo sintering and other processes, which is beneficial to energy saving and consumption reduction to a certain extent; but since the basicity of the converter final slag is controlled at 3 to 4, using low-basicity iron ore means that the lime consumption will increase further, and the cost and energy consumption will also increase accordingly. At the same time, using low-basicity iron ore will also affect the stability of converter blowing, increase the risk of splashing slag, and the metal recovery rate will be greatly reduced. In addition, there are generally more impurity elements (such as sulfur) in iron ore, which is not conducive to the stable control of molten steel quality. In recent years, some steel companies have tried to feed low-basicity iron ore in torpedo tanks or ladles, and reduce the iron in the molten iron through the [C] or [Si] elements in the molten iron. However, the slag overflow problem is significant, which restricts the implementation of this process. Summary of the invention

[0004] The present application provides a method for utilizing a molten iron ladle to consume low-basicity iron ore, so as to solve the following technical problem: how to avoid slag overflow when utilizing a molten iron ladle to consume low-basicity iron ore.

[0005] The present application provides a method for using a molten iron ladle to prepare low-basicity iron ore, the method comprising:

[0006] Obtaining first molten iron with set quality parameters;

[0007] Mixing low-basicity iron ore with lime to obtain a mixed material with a set basicity;

[0008] Filling the first molten iron into a ladle, and adding the mixed material during the filling process to obtain a ladle containing the second molten iron;

[0009] The second molten iron in the ladle is stirred.

[0010] Optionally, the set quality parameters include: molten iron temperature ≥ 1400°C, C mass fraction ≥ 4.3%, Si mass fraction ≥ 0.4%.

[0011] Optionally, the set alkalinity is 1.3 to 1.5.

[0012] Optionally, the particle size of the mixed material satisfies: the mass proportion of particles with a particle size of 0.5 mm to 3.0 mm is 100%, and the mass proportion of particles with a particle size of 0.5 mm to 2.0 mm is ≥80%.

[0013] Optionally, the basicity of the low-basicity iron ore is less than 1, and the mass fraction of CaO in the lime is ≥90%.

[0014] Optionally, the step of filling the first molten iron into a ladle and adding the mixed material during the filling process to obtain a ladle containing the second molten iron comprises:

[0015] The first molten iron is filled into a ladle. During the filling process, when the filling amount of the first molten iron reaches 1 / 4 of the total filling amount of the ladle, the mixing of the mixed material begins. When the filling amount of the first molten iron reaches 3 / 4 of the total filling amount of the ladle, the mixing of the mixed material stops, thereby obtaining a ladle containing the second molten iron.

[0016] Optionally, the dosage of the mixed material is 9kg / t·molten iron to 23kg / t·molten iron.

[0017] Optionally, the total filling volume of the ladle is 95% to 97% of the standard capacity of the ladle, and the clearance of the ladle containing the second molten iron is ≥750mm.

[0018] Optionally, after stirring the second molten iron in the ladle, the method further comprises:

[0019] According to the ratio A of the service life of the stirring head to the total service life, the stirring head speed V and the stirring time t are controlled; wherein,

[0020] When 0<A<1 / 4, 60rpm≤V<65rpm, 5.0min≤t<5.5min;

[0021] When 1 / 4≤A≤1 / 2, 65rpm≤V<75rpm, 5.5min≤t<6.5min;

[0022] When 1 / 2<A≤3 / 4, 75rpm≤V<85rpm, 6.5min≤t<7.5min;

[0023] When 3 / 4<A≤1, 85rpm≤V≤90rpm, 7.5min≤t≤8.0min.

[0024] Optionally, the stirring head is immersed in the molten iron to a depth of 1200 mm to 1500 mm.

[0025] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0026] The present application provides a method for using a hot metal ladle to feed low-basicity iron ore, comprising: obtaining a first hot metal with set quality parameters; mixing the low-basicity iron ore with lime to obtain a mixture with set basicity; filling the first hot metal into the hot metal ladle, and feeding the mixture during the filling process to obtain a hot metal ladle containing a second hot metal; stirring the second hot metal in the hot metal ladle. By controlling the hot metal conditions, the feeding system, and the stirring process, the hot metal ladle can be fed with low-basicity iron ore in a stable manner; by feeding the mixture with set basicity, the performance of the hot metal ladle's molten top slag can be controlled, and the slag overflow control of the hot metal ladle under the condition of feeding low-basicity iron ore can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0028] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0029] Figure 1 A schematic flow chart of a method for utilizing a molten iron ladle to feed low-basicity iron ore is provided in an embodiment of the present application. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0031] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0032] In addition, in the description of the specification of the present application, the terms "including", "comprising", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second", etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" means one or more, and "plurality" means two or more. "At least one", "the following at least one item (items)" or similar expressions refer to any combination of these items, including any combination of single items (items) or plural items (items). For example, "at least one of a, b, or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e. a and b), ac, bc or abc, where a, b, c can be single or plural, respectively.

[0033] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0034] Figure 1 A schematic flow chart of a method for utilizing a molten iron ladle to feed low-basicity iron ore is provided in an embodiment of the present application.

[0035] See also Figure 1 The present application provides a method for using a molten iron ladle to prepare low-basicity iron ore, the method comprising:

[0036] S1, obtaining a first molten iron with set quality parameters;

[0037] In some embodiments, the set quality parameters include: molten iron temperature ≥ 1400° C., C mass fraction ≥ 4.3%, Si mass fraction ≥ 0.4%.

[0038] The positive effects of controlling the molten iron temperature ≥ 1400°C, the mass fraction of C ≥ 4.3%, and the mass fraction of Si ≥ 0.4% are: ensuring a relatively high molten iron temperature to prevent the molten iron temperature from being too low after the addition of low-basicity iron ore and lime mixture, which affects the subsequent desulfurization; controlling the mass fractions of molten iron [C] and [Si] is to ensure the reduction effect of iron oxides in iron ore to improve the metal recovery rate. Exemplarily, the molten iron temperature can be 1400°C, 1405°C, 1410°C, 1420°C, 1430°C, etc., the mass fraction of C can be 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, etc., and the mass fraction of Si can be 0.4%, 0.45%, 0.5%, 0.55%, 0.60%, etc.

[0039] S2, mixing the low-basicity iron ore with lime to obtain a mixed material with a set basicity;

[0040] In some embodiments, the set alkalinity is 1.3-1.5.

[0041] It should be noted that the calculation method of basicity is the ratio of the mass of CaO to the mass of SiO2 in the mixture. The positive effect of setting the basicity to 1.3-1.5: When the basicity of the mixture is less than 1, a viscous molten top slag of the molten iron ladle is formed, which makes it difficult to remove the CO generated by the reaction of C in the molten iron with iron oxides in the iron ore, and it is easy to cause slag overflow. The smaller the basicity, the higher the viscosity of the molten top slag, and the more serious the slag overflow. When the basicity of the molten top slag is controlled at 1.2-1.4, the viscosity decreases, and the gas can be discharged smoothly, thereby controlling the slag overflow. At the same time, since part of the [Si] in the molten iron will be oxidized to generate SiO2 and enter the molten top slag, the basicity of the molten top slag is reduced. Therefore, the basicity of the mixture needs to be controlled within the range of 1.3-1.5. Exemplarily, the alkalinity can be set to 1.3, 1.35, 1.4, 1.45, 1.5, etc.

[0042] In some embodiments, the mass ratio of the low-basicity iron ore and the lime when mixed can be calculated based on the set basicity of the mixed material and the components of the low-basicity iron ore and the lime.

[0043] In some embodiments, the mixing is a physical mixing method.

[0044] In some embodiments, the particle size of the mixed material satisfies: the mass proportion of the particle size of 0.5 mm to 3.0 mm is 100%, and the mass proportion of the particle size of 0.5 mm to 2.0 mm is ≥80%.

[0045] The positive effect of controlling the particle size of the mixed material: From a kinetic point of view, the smaller the particle size, the better the reaction kinetic conditions, and the more conducive to the reduction of low-basicity iron ore and the melting of lime; but if the particle size is too small, the feeding process will generate dust, which is not conducive to environmental protection and also affects the yield. For example, the mass proportion of the particle size of 0.5mm to 2.0mm can be 80%, 82%, 84%, 86%, 90%, 92%, etc.

[0046] In some embodiments, the basicity of the low-basicity iron ore is less than 1, and the mass fraction of CaO in the lime is ≥90%.

[0047] The positive effect of controlling the mass fraction of CaO in lime to ≥ 90% is as follows: by controlling the mass fraction of CaO, the purity of lime is high, and then less impurities enter the molten iron ladle, which can control the environmental pollution caused by the volatilization of impurities at high temperatures and the impact of impurities on the quality of molten iron; in addition, the higher the purity of lime, the less the corresponding amount added under a certain alkalinity requirement, which is also conducive to the control of slag overflow. For example, the mass fraction of CaO in lime can be 90%, 91%, 92%, 93%, 94%, 95%, etc.

[0048] S3, filling the first molten iron into a ladle, and adding the mixed material during the filling process to obtain a ladle containing the second molten iron;

[0049] In some embodiments, the step of filling the first molten iron into a ladle and adding the mixed material during the filling process to obtain a ladle containing the second molten iron comprises:

[0050] The first molten iron is filled into a ladle. During the filling process, when the filling amount of the first molten iron reaches 1 / 4 of the total filling amount of the ladle, the mixing of the mixed material begins. When the filling amount of the first molten iron reaches 3 / 4 of the total filling amount of the ladle, the mixing of the mixed material stops, thereby obtaining a ladle containing the second molten iron.

[0051] During the process of molten iron filling, a mixture of low-alkalinity iron ore and lime is added without affecting the production rhythm. At the same time, the impact of the falling iron flow is used to accelerate the melting of the mixture of low-alkalinity iron ore and lime, and its reaction with the molten iron.

[0052] When the first molten iron filling volume reaches 1 / 4 of the total filling volume of the ladle, start adding the mixed material. If it is added too early, the lime will easily stick to the bottom of the ladle. When the first molten iron filling volume reaches 3 / 4 of the total filling volume of the ladle, stop adding the mixed material. If it continues to be added, the melting effect of the subsequently added low-alkalinity iron ore and lime mixed material cannot be guaranteed.

[0053] In some embodiments, the dosage of the mixed material is 9kg / t·molten iron to 23kg / t·molten iron.

[0054] It should be noted that the amount of mixed material can be controlled according to the temperature of the molten iron and the age of the ladle. The higher the temperature of the molten iron and the older the ladle (the greater the erosion of the inner wall refractory material and the larger the ladle capacity), the amount of mixed material is controlled according to the upper limit; the lower the temperature of the molten iron and the younger the age of the ladle, the amount of mixed material is controlled according to the lower limit. Exemplarily, the amount of mixed material can be 9kg / t·molten iron, 11kg / t·molten iron, 13kg / t·molten iron, 15kg / t·molten iron, 20kg / t·molten iron, 23kg / t·molten iron, etc.

[0055] In some embodiments, the total filling volume of the ladle is 95% to 97% of the standard capacity of the ladle, and the clearance of the ladle containing the second molten iron is ≥ 750 mm. Exemplarily, the total filling volume of the ladle can be 95%, 95.5%, 96%, 96.5%, 97%, etc. of the standard capacity of the ladle, and the clearance of the ladle containing the second molten iron can be 750 mm, 780 mm, 800 mm, 820 mm, etc.

[0056] S4, stirring the second molten iron in the ladle.

[0057] In some embodiments, before step S4, the method includes: transferring the molten iron ladle to a KR desulfurization station.

[0058] In some embodiments, after stirring the second molten iron in the ladle, the method further comprises:

[0059] According to the ratio A of the service life of the stirring head to the total service life, the stirring head speed V and the stirring time t are controlled; wherein,

[0060] When 0<A<1 / 4, 60rpm≤V<65rpm, 5.0min≤t<5.5min;

[0061] When 1 / 4≤A≤1 / 2, 65rpm≤V<75rpm, 5.5min≤t<6.5min;

[0062] When 1 / 2<A≤3 / 4, 75rpm≤V<85rpm, 6.5min≤t<7.5min;

[0063] When 3 / 4<A≤1, 85rpm≤V≤90rpm, 7.5min≤t≤8.0min.

[0064] In some embodiments, the stirring head is immersed in the molten iron to a depth of 1200 mm to 1500 mm.

[0065] After the molten iron is filled with iron, it enters the KR desulfurization station, and the stirring device is started to stir the molten iron, further strengthening the reaction between the molten iron and the low-alkalinity iron ore and improving the metal recovery rate; in addition, stirring also promotes the reaction between the molten iron and the lime, achieving a certain desulfurization effect. As the service life of the stirring head increases, its erosion intensifies, the blades deform, and the stirring effect weakens. It is necessary to increase the speed and stirring time to ensure the stirring effect. Exemplarily, when the ratio of the service life of the stirring head to the total service life is 1 / 8, the stirring head speed is 60rpm and the stirring time is 5min; when the ratio of the service life of the stirring head to the total service life is 1 / 2, the stirring head speed is 70rpm and the stirring time is 6min; when the ratio of the service life of the stirring head to the total service life is 3 / 4, the stirring head speed is 80rpm and the stirring time is 7min; when the ratio of the service life of the stirring head to the total service life is 7 / 8, the stirring head speed is 90rpm and the stirring time is 8min. Exemplarily, the immersion depth of the stirring head into the molten iron can be 1200 mm, 1300 mm, 1400 mm, 1450 mm, 1500 mm, etc.

[0066] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to industry standards. If there is no corresponding industry standard, then the conditions recommended by the manufacturer are followed.

[0067] The following examples and comparative examples are all based on a ladle with a standard capacity of 220 t.

[0068] Example 1

[0069] This embodiment provides a method for using a molten iron ladle to prepare low-basicity iron ore, comprising the following steps:

[0070] S11, obtaining the first molten iron, wherein the temperature of the molten iron before adding the low-basicity iron ore is 1410°C, the mass fraction of C in the molten iron is 4.5%, and the mass fraction of Si in the molten iron is 0.42%;

[0071] S21, mixing low-basicity iron ore with lime to obtain a mixed material with a basicity of 1.3; wherein the CaO mass fraction of the lime is 90%, and the mass proportion of the mixed material in the range of 0.5 to 2.0 mm is 82%;

[0072] S31, filling the first molten iron into a ladle, during the filling process, when the first molten iron filling volume reaches 1 / 4 of the total filling volume of the ladle, starting to feed the mixed material, and when the first molten iron filling volume reaches 3 / 4 of the total filling volume of the ladle, stopping feeding the mixed material to obtain a ladle containing the second molten iron; wherein the clearance of the ladle containing the second molten iron is 800 mm, the total filling volume of the ladle is 96% of the standard capacity, and the feeding amount of the mixed material is 15 kg / t·molten iron;

[0073] S41. After the molten iron is loaded, it enters the KR desulfurization station and the stirring device is started to stir the molten iron. The speed of the stirring head is 70rpm, the stirring time is 6min, and the depth of the stirring head immersed in the molten iron is 1200mm.

[0074] Example 2

[0075] This embodiment provides a method for using a molten iron ladle to prepare low-basicity iron ore, comprising the following steps:

[0076] S11, obtaining the first molten iron, wherein the temperature of the molten iron before adding the low-basicity iron ore is 1415°C, the mass fraction of C in the molten iron is 4.4%, and the mass fraction of Si in the molten iron is 0.45%;

[0077] S21, low-basicity iron ore is mixed with lime to obtain a mixed material with a basicity of 1.5; wherein the CaO mass fraction of the lime is 90%, and the mass proportion of the mixed material in the range of 0.5 to 2.0 mm is 85%;

[0078] S31, filling the first molten iron into a ladle, during the filling process, when the first molten iron filling volume reaches 1 / 4 of the total filling volume of the ladle, starting to feed the mixed material, and when the first molten iron filling volume reaches 3 / 4 of the total filling volume of the ladle, stopping feeding the mixed material to obtain a ladle containing the second molten iron; wherein the clearance of the ladle containing the second molten iron is 820 mm, the total filling volume of the ladle is 96% of the standard capacity, and the feeding amount of the mixed material is 20 kg / t·molten iron;

[0079] S41. After the molten iron is loaded into the ladle, it enters the KR desulfurization station. The stirring device is started to stir the molten iron. The speed of the stirring head is 85rpm, the stirring time is 8min, and the depth of the stirring head immersed in the molten iron is 1500mm.

[0080] Comparative Example 1

[0081] This comparative example provides a method for preparing low-basicity iron ore using a hot metal ladle, comprising the following steps:

[0082] S11, obtaining the first molten iron, wherein the temperature of the molten iron before adding the low-basicity iron ore is 1380°C, the mass fraction of C in the molten iron is 3.7%, and the mass fraction of Si in the molten iron is 0.35%;

[0083] S21, mixing low-basicity iron ore with lime to obtain a mixed material with a basicity of 1.4; wherein the CaO mass fraction of the lime is 90%, and the mass proportion of the mixed material in the range of 0.5 to 2.0 mm is 83%;

[0084] S31, filling the first molten iron into a ladle, during the filling process, when the first molten iron filling volume reaches 1 / 4 of the total filling volume of the ladle, starting to feed the mixed material, and when the first molten iron filling volume reaches 3 / 4 of the total filling volume of the ladle, stopping feeding the mixed material to obtain a ladle containing the second molten iron; wherein the clearance of the ladle containing the second molten iron is 820 mm, the total filling volume of the ladle is 96% of the standard capacity, and the feeding amount of the mixed material is 12 kg / t·molten iron;

[0085] S41. After the molten iron is loaded into the ladle, it enters the KR desulfurization station. The stirring device is started to stir the molten iron. The speed of the stirring head is 70rpm, the stirring time is 6min, and the depth of the stirring head immersed in the molten iron is 1500mm.

[0086] Comparative Example 2

[0087] This comparative example provides a method for preparing low-basicity iron ore using a hot metal ladle, comprising the following steps:

[0088] S11, obtaining the first molten iron, wherein the temperature of the molten iron before adding the low-basicity iron ore is 1407°C, the mass fraction of C in the molten iron is 4.4%, and the mass fraction of Si in the molten iron is 0.42%;

[0089] S21, mixing low-basicity iron ore with lime to obtain a mixed material with a basicity of 1.4; wherein the CaO mass fraction of the lime is 90%, and the mass proportion of the mixed material in the range of 0.5 to 2.0 mm is 83%;

[0090] S31, filling the first molten iron into a ladle, during the filling process, when the first molten iron filling volume reaches 1 / 4 of the total filling volume of the ladle, starting to feed the mixed material, and when the first molten iron filling volume reaches 3 / 4 of the total filling volume of the ladle, stopping feeding the mixed material to obtain a ladle containing the second molten iron; wherein the clearance of the ladle containing the second molten iron is 800 mm, the total filling volume of the ladle is 96% of the standard capacity, and the feeding amount of the mixed material is 16 kg / t·molten iron;

[0091] Comparative Example 3

[0092] This comparative example provides a method for preparing low-basicity iron ore using a hot metal ladle, comprising the following steps:

[0093] S11, obtaining the first molten iron, wherein the temperature of the molten iron before adding the low-basicity iron ore is 1409°C, the mass fraction of C in the molten iron is 4.5%, and the mass fraction of Si in the molten iron is 0.40%;

[0094] S21, filling the first molten iron into a ladle, during the filling process, when the first molten iron filling volume reaches 1 / 4 of the total filling volume of the ladle, starting to add low-basicity iron ore, when the first molten iron filling volume reaches 3 / 4 of the total filling volume of the ladle, stopping adding the low-basicity iron ore, and obtaining a ladle containing the second molten iron; wherein the clearance of the ladle containing the second molten iron is 820 mm, the total filling volume of the ladle is 96% of the standard capacity, the amount of low-basicity iron ore added is 10 kg / t·molten iron, the alkalinity of the low-basicity iron ore is 0.3, and the mass proportion of the particle size within the range of 0.5 to 2.0 mm is 85%;

[0095] S31. After the molten iron is loaded into the ladle, it enters the KR desulfurization station. The stirring device is started to stir the molten iron. The speed of the stirring head is 80rpm, the stirring time is 7min, and the depth of the stirring head immersed in the molten iron is 1250mm.

[0096] The application effect of the method of the present invention is characterized by whether there is slag overflow in the ladle and the mass fraction of TFe in the molten top slag of the ladle; wherein the mass fraction of TFe represents the recovery rate of iron element in low-basicity iron ore, and the lower the TFe value, the higher the metal recovery rate. The comparison of slag overflow in the ladle and the mass fraction of TFe in the molten top slag of the embodiment and the comparative example is shown in Table 1.

[0097] It is pointed out here that after the iron ladle is fed with low-alkalinity iron ore or a mixture of low-alkalinity iron ore and lime, the slag is skimmed after stirring (or not stirring). The skimmed slag is called pre-desulfurization slag, and the molten top slag of the iron ladle is taken from the pre-desulfurization slag.

[0098] Table 1 Comparison of ladle slag overflow problem and molten top slag TFe mass fraction in the embodiment and comparative example

[0099] Group Is there any slag overflow? Mass ratio of molten top slag TFe, % Example 1 no 3.25 Example 2 no 2.73 Comparative Example 1 no 7.07 Comparative Example 2 no 12.48 Comparative Example 3 yes 10.20

[0100] As can be seen from Table 1, the methods of using a molten iron ladle to feed low-alkalinity iron ore provided in Examples 1 and 2 do not cause slag overflow in the molten iron ladle, and at the same time, the recovery rate of iron in the low-alkalinity iron ore is relatively high; Comparative Example 1 does not cause slag overflow, but since the quality parameters of the molten iron before feeding do not meet the requirements, the recovery rate of iron is relatively low; Comparative Example 2 does not cause slag overflow, but since the molten iron is not stirred after feeding, the recovery rate of iron is relatively low; Comparative Example 3 only feeds low-alkalinity iron ore, and a slag overflow problem occurs.

[0101] In addition, one or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0102] In the embodiment of the present invention, the stable loading of low-basicity iron ore in the molten iron ladle is achieved by controlling the molten iron conditions, the feeding system, the stirring process, etc.

[0103] In the embodiment of the present invention, the slag overflow control of the ladle under the condition of low basicity iron ore is achieved by controlling the performance of the molten top slag of the ladle.

[0104] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for preparing low-basicity iron ore using a hot metal ladle, characterized in that: The method comprises: Obtaining first molten iron with set quality parameters; Mixing low-basicity iron ore with lime to obtain a mixed material with a set basicity; Filling the first molten iron into a ladle, and adding the mixed material during the filling process to obtain a ladle containing the second molten iron; The second molten iron in the ladle is stirred.

2. The method according to claim 1, characterized in that The set quality parameters include: molten iron temperature ≥ 1400° C., C mass fraction ≥ 4.3%, Si mass fraction ≥ 0.4%.

3. The method according to claim 1, characterized in that The set alkalinity is 1.3 to 1.

5.

4. The method according to claim 1, characterized in that The particle size of the mixed material satisfies: the mass proportion of the particle size of 0.5 mm to 3.0 mm is 100%, and the mass proportion of the particle size of 0.5 mm to 2.0 mm is ≥80%.

5. The method according to claim 1, characterized in that: The basicity of the low-basicity iron ore is less than 1, and the mass fraction of CaO in the lime is ≥90%.

6. The method according to claim 1, characterized in that The method of filling the first molten iron into a ladle and adding the mixed material during the filling process to obtain a ladle containing the second molten iron comprises: The first molten iron is filled into a ladle. During the filling process, when the filling amount of the first molten iron reaches 1 / 4 of the total filling amount of the ladle, the mixing of the mixed material begins. When the filling amount of the first molten iron reaches 3 / 4 of the total filling amount of the ladle, the mixing of the mixed material stops, thereby obtaining a ladle containing the second molten iron.

7. The method according to claim 6, characterized in that The dosage of the mixed material is 9kg / t·molten iron to 23kg / t·molten iron.

8. The method according to claim 6, characterized in that The total filling volume of the ladle is 95% to 97% of the standard capacity of the ladle, and the clearance of the ladle containing the second molten iron is ≥750mm.

9. The method according to claim 1, characterized in that: After stirring the second molten iron in the ladle, the method further includes: According to the ratio A of the service life of the stirring head to the total service life, the stirring head speed V and the stirring time t are controlled; wherein, When 0<A<1 / 4, 60rpm≤V<65rpm, 5.0min≤t<5.5min; When 1 / 4≤A≤1 / 2, 65rpm≤V<75rpm, 5.5min≤t<6.5min; When 1 / 2<A≤3 / 4, 75rpm≤V<85rpm, 6.5min≤t<7.5min; When 3 / 4<A≤1, 85rpm≤V≤90rpm, 7.5min≤t≤8.0min.

10. The method according to claim 9, characterized in that The stirring head is immersed in the molten iron to a depth of 1200 mm to 1500 mm.

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