Magnetic separation powder re-sintering treatment method

Abstract

The invention relates to the field of steel slag treatment, in particular to a magnetic separation powder re-sintering treatment method which comprises the following steps: obtaining magnetic separation powder of different size fractions; obtaining the phosphorus content of the magnetic separation powder of each fraction; and under the condition that various parameters of the sinter meet the production requirements, the adding priority of the magnetic separation powder of different particle fractions instead of the mineral powder to enter the sintering and blending material is adjusted according to the surplus amount of the phosphorus load of the sinter and the phosphorus content of the magnetic separation powder of each particle fraction. According to the characteristic that the phosphorus content of each fraction of the magnetic separation powder is different, the proportion of adding the magnetic separation powder of different fractions to replace the mineral powder is calculated through the surplus amount of the phosphorus load of the sintered ore, and meanwhile, the adding priority of the magnetic separation powder of each fraction can be determined according to the phosphorus content of the magnetic separation powder of each fraction; therefore, the adding amount of the converter magnetic separation powder during sintering is increased to the maximum extent, the additional value of the magnetic separation powder is increased as much as possible, and meanwhile the problem that the phosphorus load of sintered ore exceeds the standard due to direct adding of the magnetic separation powder is avoided.

Description

Technical Field

[0001] The invention relates to the field of steel slag treatment, and in particular to a magnetic separation powder re-sintering treatment method. Background Art

[0002] Converter steelmaking uses molten iron, scrap steel, and ferroalloys as the main raw materials, and adds slag materials such as lime and dolomite. It does not rely on external energy, but relies on the physical heat of the molten iron itself and the chemical reaction between the components of the molten iron to generate heat to complete the steelmaking process in the converter. After the converter smelting is completed, the qualified molten steel produced is cast into steel billets and transported to the rolling workshop for processing, while the generated steel slag is sent to the steel slag workshop for treatment. Among them, steel slag refers to the molten slag discharged during the steelmaking process. It is composed of oxides such as calcium, iron, silicon, magnesium, aluminum, manganese, titanium, sulfur, and phosphorus. It is an industrial solid waste. The discharge volume is 15-20% of the crude steel output, and its iron content is relatively high, with an iron grade of about 20%. It has a certain smelting value. How to effectively treat steel slag has always been an important topic of research.

[0003] At present, steel slag can be used to obtain magnetic powder through hot stewing-rod grinding-magnetic separation process and then sintered for reuse. However, the harmful elements in steel slag are relatively high, especially phosphorus, which can easily lead to excessive phosphorus content in subsequent blast furnace molten iron, thereby affecting the quality of steel products. In this regard, Chinese patent document CN118147390A discloses a method for recycling converter magnetic powder, which crushes and processes the steel slag produced during the converter smelting process, selects magnetic powder with an iron grade of about 50%, and adds it to the mixed material in the raw material field through ore blending calculation, transports it to the sintering plant for roasting into finished sintered ore, and then sends it to the blast furnace to smelt qualified molten iron, and finally sends it to the converter to be smelted into qualified steel billets, and so on. The cycle is repeated, realizing self-production and self-consumption in the factory, reducing the environmental protection pressure of the society. However, based on the restrictions on the phosphorus content of sintered ore in the production of various quality steels, the amount of magnetic powder added is still relatively low, and how to further increase the amount of magnetic powder added needs to be solved urgently. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect of low amount of magnetic powder added in the existing magnetic powder recovery method, thereby providing a magnetic powder sintering method to solve the above problem.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A method for sintering magnetically separated powder, comprising:

[0007] Obtain magnetic separation powder of different particle sizes;

[0008] Obtain the phosphorus content of magnetic separation powder of each particle size;

[0009] Under the condition that all parameters of sintered ore meet the production requirements, the priority of adding magnetic separation powder of different particle sizes to the sintered mixed material instead of ore powder is adjusted according to the surplus phosphorus load of the sintered ore and the phosphorus content of magnetic separation powder of each particle size.

[0010] Preferably, the iron grade of the magnetically separated powders of different particle sizes is 55-65%.

[0011] Preferably, the process of obtaining magnetic separation powders of different particle sizes includes: pre-treating steel slag, recovering slag steel through magnetic separation, and rod-milling and magnetically separating the remaining steel slag.

[0012] Preferably, the pretreatment is hot stewing, and the mechanism involved is: utilizing the sensible heat of the high-temperature molten slag, the temperature stress generated when it meets water, and the hydrolysis of free calcium oxide to cause the slag to crack.

[0013] Preferably, the frequency of the double magnetic rollers in the re-magnetic separation step is 45-50 Hz.

[0014] In the present invention, the particle size distribution range of magnetic separation powder of different particle sizes and the number of particle size distribution groups can be set arbitrarily, and the number of particle size distribution groups should be ≥2 groups, for example: it can be set to 2 groups, 3 groups, 4 groups, 5 groups or even more than 5 groups; in order to meet the purpose of more accurate addition to achieve a higher addition amount, the number of particle size distribution groups should be set to ≥3 groups, but if the number of particle size distribution groups is too large, it will lead to a relatively complicated process;

[0015] Therefore, preferably, in the present invention, the rod mill processes the remaining slag into five particle size distribution groups, and the particle size distribution range of each of the five particle size distribution groups can be set by itself, as long as it can cover the particle size range of the screened magnetic separation powder. For example, the particle size range of each group can be set to 0-3mm, 3-5mm, 5-8mm, 8-12mm, >12mm, or to 0-2mm, 2-5mm, 5-10mm, 10-15mm, >15mm; the above ranges do not include the lower limit value but include the upper limit value, that is, 0-2mm means that the contained particle size is greater than 0mm and ≤2mm.

[0016] Based on the different particle size distribution requirements of the particle size distribution groups, each particle size distribution group will obtain a different proportion of magnetic separation powder within a specific iron grade range. By obtaining the phosphorus content of different particle size distribution groups and matching it with the surplus amount of phosphorus load of the sintered ore, the proportion of slag that achieves the optimal addition amount can be effectively obtained.

[0017] Among them, the phosphorus content of magnetic separation powder of each particle size can be directly detected, but based on the principle of simple processing technology, it is preferred to analyze and fit the phosphorus distribution of different particle sizes of magnetic separation powder with different phosphorus content to obtain the distribution law of phosphorus in different particle sizes, and obtain the phosphorus content of each particle size according to the average phosphorus content of the magnetic separation powder.

[0018] In the present invention, the particle size ranges of each particle size distribution group are set to 0-2mm, 2-5mm, 5-10mm, 10-15mm, and >15mm, and at the same time, the 0-2mm magnetic separation powder accounts for 0-10%, the 2-5mm magnetic separation powder accounts for 5-10%, the 5-10mm magnetic separation powder accounts for 65-70%, the 10-15mm magnetic separation powder accounts for 10-15%, and the >15mm magnetic separation powder accounts for 0-10%. The distribution rules in the distribution groups are: a1=1.249b+0.001, a2=0.753b+0.009, a3=0.877b-0.008, a4=1.258b+0.007, a5=1.874b+0.021; among them, b is the average phosphorus content of magnetic separation powder, %; a1-a5 are the phosphorus contents of magnetic separation powders of five particle sizes of 0-2mm, 2-5mm, 5-10mm, 10-15mm, and >15mm, %.

[0019] In order to achieve the above-mentioned requirements on the proportion of magnetic separation powder in each particle size distribution group after re-magnetic separation, the proportion of steel slag in each particle size distribution group before re-magnetic separation and after rod mill treatment is: 0-2mm steel slag accounts for 5-10%, 2-5mm steel slag accounts for 10-15%, 5-10mm steel slag accounts for 60-65%, 10-15mm steel slag accounts for 5-10%, and >15mm steel slag accounts for 0-10%.

[0020] In the present invention, the calculation formula for the addition ratio of each particle size of the magnetic separation powder is: Lk=(H1a1+H2a2+H3a3+H4a4+H5a5)-p(H1+H2+H3+H4+H5), wherein L is the phosphorus load of the sintered ore, %; k is the phosphorus content of the sintered mixed material without adding magnetic separation powder, %; H1-H5 are the addition ratios of the five particle sizes of 0-2mm, 2-5mm, 5-10mm, 10-15mm, and >15mm magnetic separation powder in the sintered mixed material, %; p is the average phosphorus content of the ore powder replaced by the magnetic separation powder, %.

[0021] Preferably, the priority of adding the magnetic separation powder to the sintered mixed material is (2-5mm)>(5-10mm)>(0-2mm)>(10-15mm)>(>15mm).

[0022] Preferably, the mineral powder is at least one of Indian powder, Jinbuba powder, Australian PB powder, Yangdi powder, FMG super special powder, FMG mixed powder, Robe River powder, Meishan fine powder and returned ore.

[0023] Preferably, when the sum of the proportions of magnetic separation powders of various particle sizes is ≤0.5%, no magnetic separation powder is added to the sintered mixed material.

[0024] In the present invention, the process of magnetic separation recovery of slag steel is: using a grid screen to preliminarily separate slag steel with a particle size of ≥450mm and residual steel slag with a particle size of <450mm, and using a suction cup to suck away the slag steel.

[0025] The technical solution of the present invention has the following advantages:

[0026] 1. A method for processing magnetic powder by sintering, comprising: obtaining magnetic powder of different particle sizes; obtaining the phosphorus content of magnetic powder of each particle size; and adjusting the priority of adding magnetic powder of different particle sizes to replace mineral powder into the sintering mixed material according to the surplus of phosphorus load of sintered ore and the phosphorus content of magnetic powder of each particle size, under the condition that various parameters of sintered ore meet production requirements. According to the characteristics of different phosphorus contents of magnetic powder of different particle sizes, the present invention calculates the proportion of adding magnetic powder of different particle sizes to replace mineral powder by the surplus of phosphorus load of sintered ore, and determines the priority of adding magnetic powder of each particle size according to the phosphorus content of magnetic powder of each particle size, so as to maximize the addition amount of converter magnetic powder in sintering, increase the added value of magnetic powder as much as possible, and avoid the problem of excessive phosphorus load of sintered ore caused by direct addition of magnetic powder.

[0027] 2. In the magnetic separation powder re-sintering treatment method of the present invention, the particle size distribution and iron grade of the converter magnetic separation powder are regulated by adjusting the parameters of the rod mill and the double magnetic rollers.

[0028] 3. In the magnetic powder re-sintering treatment method of the present invention, the magnetic powder is treated as follows: 0-2mm magnetic powder accounts for 0-10%, 2-5mm magnetic powder accounts for 5-10%, 5-10mm magnetic powder accounts for 60-70%, 10-15mm magnetic powder accounts for 10-15%, and >15mm magnetic powder accounts for 0-10%. If all magnetic powders are treated as magnetic powders with a lower phosphorus content in the converter slag treatment process (for example, all are treated as 2-5mm particle size), the effect can be improved, but the current treatment process does not meet the conditions, and the treatment cost will be much higher than the value of the magnetic powder itself, and the recovery rate of iron in the slag will be greatly reduced.

[0029] 4. In the magnetic powder re-sintering treatment method of the present invention, when the sum of the addition ratios of magnetic powders of various particle sizes is ≤0.5%, no more magnetic powder will be added to the sintered mixed material to avoid uneven sintering and incomplete mixing due to low addition of magnetic powder, thereby avoiding the problem of segregation of sintered ore components. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 is the fitting curve of the distribution law of phosphorus element in the 0-2 mm particle size in Example 1 of the present invention;

[0032] Figure 2 is the fitting curve of the distribution law of phosphorus element in the 2-5 mm particle size in Example 1 of the present invention;

[0033] Figure 3 is the fitting curve of the phosphorus distribution law of the 5-10 mm particle size in Example 1 of the present invention;

[0034] Figure 4 is the fitting curve of the distribution law of phosphorus element in the 10-15 mm particle size in Example 1 of the present invention;

[0035] Figure 5 It is the fitting curve of the distribution law of phosphorus element in the particle size of >15 mm in Example 1 of the present invention. DETAILED DESCRIPTION

[0036] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0037] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0038] Example 1

[0039] This embodiment provides a method for sintering magnetic separation powder, and the specific steps are as follows:

[0040] (1) First, the distribution of phosphorus in different particle sizes (0-2 mm, 2-5 mm, 5-10 mm, 10-15 mm, >15 mm) of magnetic separation powders with average phosphorus contents in the range of 0.6-1.1% (specifically 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1.0%, 1.05%, 1.1%) was analyzed and fitted to obtain the distribution law of phosphorus in different particle sizes. The fitting curve of the phosphorus distribution law of each particle size of the magnetic separation powder was as follows: Figure 1-Figure 5 As shown, the applicable range of the fitting curve is: 0-2mm magnetic separation powder accounts for 0-10%, 2-5mm magnetic separation powder accounts for 5-10%, 5-10mm magnetic separation powder accounts for 65-70%, 10-15mm magnetic separation powder accounts for 10-15%, and >15mm magnetic separation powder accounts for 0-10%; for example, when all processing is 2-5mm, it will no longer be applicable.

[0041] (2) The converter slag is hot-stemmed and magnetically separated to recover slag steel, and then the remaining slag is rod-milled (specific parameters are motor power 500 kW, motor speed 740 r / min, voltage 10000 V, frequency 50 Hz) to obtain slag with five particle size distributions: 0-2 mm slag accounts for 5%, 2-5 mm slag accounts for 15%, 5-10 mm slag accounts for 65%, 10-15 mm slag accounts for 10%, and >15 mm slag accounts for 5%.

[0042] (3) The steel slag obtained in step (2) is subjected to magnetic separation at a frequency of 45 Hz of double magnetic rollers to obtain magnetic separation powders with five particle size distributions, namely, 0-2 mm converter magnetic separation powder accounting for 7%, 2-5 mm converter magnetic separation powder accounting for 8%, 5-10 mm converter magnetic separation powder accounting for 68%, 10-15 mm converter magnetic separation powder accounting for 10%, and >15 mm converter magnetic separation powder accounting for 7%. The iron grade of the converter magnetic powder is 60%, and the average phosphorus content of the converter magnetic powder is 0.9%. The phosphorus element of each particle size is obtained according to the fitting curve obtained in step (1): the phosphorus content of the 0-2 mm converter magnetic powder is 1.1251%, the phosphorus content of the 2-5 mm converter magnetic powder is 0.6867%, the phosphorus content of the 5-10 mm converter magnetic powder is 0.7813%, the phosphorus content of the 10-15 mm converter magnetic powder is 1.1392%, and the phosphorus content of the converter magnetic powder >15 mm is 1.7076%.

[0043] (4) The phosphorus content of the sintered mixed material without adding magnetic separation powder is 0.065%. 2-5mm converter magnetic separation powder is used at a ratio of 1.1% to replace FMG super special powder. After adding converter magnetic separation powder, the phosphorus content of the sintered mixed material is 0.0719%, the phosphorus content of the sintered ore is 0.0682%, and the phosphorus content of the blast furnace iron is 0.116%, which meets the requirement of P < 0.12% in the process regulations and has no effect on the next process.

[0044] Example 2

[0045] This embodiment provides a method for sintering magnetic separation powder, and the specific steps are as follows:

[0046] (1) The converter slag is hot-stemmed and magnetically separated to recover slag steel, and then the remaining slag is rod-milled (specific parameters are motor power 500 kW, motor speed 740 r / min, voltage 10000 V, frequency 50 Hz) to obtain slag with five particle size distributions: 0-2 mm slag accounts for 5%, 2-5 mm slag accounts for 15%, 5-10 mm slag accounts for 65%, 10-15 mm slag accounts for 10%, and >15 mm slag accounts for 5%.

[0047] (2) The steel slag obtained in step (1) is subjected to magnetic separation, and the frequency of the magnetic separation double magnetic drum is 45Hz, and magnetic separation powders with five particle size distributions are obtained, namely, 0-2mm converter magnetic separation powder accounts for 7%, 2-5mm converter magnetic separation powder accounts for 8%, 5-10mm converter magnetic separation powder accounts for 68%, 10-15mm converter magnetic separation powder accounts for 10%, and >15mm converter magnetic separation powder accounts for 7%. The iron grade of the converter magnetic separation powder is 60%, and the average phosphorus content of the converter magnetic separation powder is 0.9%. The phosphorus element of each particle size is obtained according to the fitting curve obtained in Example 1: the phosphorus content of the 0-2mm converter magnetic separation powder is 1.1251%, the phosphorus content of the 2-5mm converter magnetic separation powder is 0.6867%, the phosphorus content of the 5-10mm converter magnetic separation powder is 0.7813%, the phosphorus content of the 10-15mm converter magnetic separation powder is 1.1392%, and the phosphorus content of the >15mm converter magnetic separation powder is 1.7076%.

[0048] (3) The phosphorus content of the sintered mixed material without adding magnetic separation powder is 0.065%. 5-10 mm converter magnetic separation powder is used at a ratio of 0.95% to replace FMG super special powder. After adding converter magnetic separation powder, the phosphorus content of the sintered mixed material is 0.072%, the phosphorus content of the sintered ore is 0.0684%, and the phosphorus content of the blast furnace iron is 0.116%, which meets the requirement of P < 0.12% in the process regulations and has no effect on the next process.

[0049] Example 3

[0050] This embodiment provides a method for sintering magnetic separation powder, and the specific steps are as follows:

[0051] (1) The converter slag is hot-stemmed and magnetically separated to recover slag steel, and then the remaining slag is rod-milled (specific parameters are motor power 500 kW, motor speed 740 r / min, voltage 10000 V, frequency 50 Hz) to obtain slag with five particle size distributions: 0-2 mm slag accounts for 5%, 2-5 mm slag accounts for 15%, 5-10 mm slag accounts for 65%, 10-15 mm slag accounts for 10%, and >15 mm slag accounts for 5%.

[0052] (2) The steel slag obtained in step (1) is subjected to magnetic separation, and the frequency of the magnetic separation double magnetic drum is 45Hz, and magnetic separation powders with five particle size distributions are obtained, namely, 0-2mm converter magnetic separation powder accounts for 7%, 2-5mm converter magnetic separation powder accounts for 8%, 5-10mm converter magnetic separation powder accounts for 68%, 10-15mm converter magnetic separation powder accounts for 10%, and >15mm converter magnetic separation powder accounts for 7%. The iron grade of the converter magnetic separation powder is 60%, and the average phosphorus content of the converter magnetic separation powder is 0.9%. The phosphorus element of each particle size is obtained according to the fitting curve obtained in Example 1: the phosphorus content of the 0-2mm converter magnetic separation powder is 1.1251%, the phosphorus content of the 2-5mm converter magnetic separation powder is 0.6867%, the phosphorus content of the 5-10mm converter magnetic separation powder is 0.7813%, the phosphorus content of the 10-15mm converter magnetic separation powder is 1.1392%, and the phosphorus content of the >15mm converter magnetic separation powder is 1.7076%.

[0053] (3) The phosphorus content of the sintered mixed material without adding magnetic separation powder is 0.055%. 5-10 mm converter magnetic separation powder is used at a ratio of 1.9% to replace Indian powder. After adding converter magnetic separation powder, the phosphorus content of the sintered mixed material is 0.0677%, the phosphorus content of the sintered ore is 0.0643%, and the phosphorus content of the blast furnace iron is 0.110%, which meets the requirement of P < 0.12% in the process regulations and has no effect on the next process.

[0054] Example 4

[0055] This embodiment provides a method for sintering magnetic separation powder, and the specific steps are as follows:

[0056] (1) The converter slag is hot-stemmed and magnetically separated to recover slag steel, and then the remaining slag is rod-milled (specific parameters are motor power 500 kW, motor speed 740 r / min, voltage 10000 V, frequency 50 Hz) to obtain slag with five particle size distributions: 0-2 mm slag accounts for 5%, 2-5 mm slag accounts for 15%, 5-10 mm slag accounts for 65%, 10-15 mm slag accounts for 10%, and >15 mm slag accounts for 5%.

[0057] (2) The steel slag obtained in step (1) is subjected to magnetic separation, and the frequency of the magnetic separation double magnetic drum is 45Hz, and magnetic separation powders with five particle size distributions are obtained, namely, 0-2mm converter magnetic separation powder accounts for 7%, 2-5mm converter magnetic separation powder accounts for 8%, 5-10mm converter magnetic separation powder accounts for 68%, 10-15mm converter magnetic separation powder accounts for 10%, and >15mm converter magnetic separation powder accounts for 7%. The iron grade of the converter magnetic separation powder is 60%, and the average phosphorus content of the converter magnetic separation powder is 0.9%. The phosphorus element of each particle size is obtained according to the fitting curve obtained in Example 1: the phosphorus content of the 0-2mm converter magnetic separation powder is 1.1251%, the phosphorus content of the 2-5mm converter magnetic separation powder is 0.6867%, the phosphorus content of the 5-10mm converter magnetic separation powder is 0.7813%, the phosphorus content of the 10-15mm converter magnetic separation powder is 1.1392%, and the phosphorus content of the >15mm converter magnetic separation powder is 1.7076%.

[0058] (3) The phosphorus content of the sintered mixed material without adding magnetic separation powder is 0.055%. 10-15mm converter magnetic separation powder is used at a ratio of 1.4% to replace Indian powder. After adding converter magnetic separation powder, the phosphorus content of the sintered mixed material is 0.0691%, the phosphorus content of the sintered ore is 0.0656%, and the phosphorus content of the blast furnace iron is 0.113%, which meets the requirement of P < 0.12% in the process regulations and has no effect on the next process.

[0059] Example 5

[0060] This embodiment provides a method for sintering magnetic separation powder, and the specific steps are as follows:

[0061] (1) The converter slag is hot-stemmed and magnetically separated to recover slag steel, and then the remaining slag is rod-milled (specific parameters are motor power 500 kW, motor speed 740 r / min, voltage 10000 V, frequency 55 Hz) to obtain slag with five particle size distributions: 0-2 mm slag accounts for 10%, 2-5 mm slag accounts for 15%, 5-10 mm slag accounts for 60%, 10-15 mm slag accounts for 10%, and >15 mm slag accounts for 5%.

[0062] (2) The steel slag obtained in step (1) is subjected to magnetic separation, and the frequency of the double magnetic rollers for magnetic separation is 50 Hz, to obtain magnetic separation powders with five particle size distributions, namely, 0-2 mm converter magnetic separation powder accounts for 10%, 2-5 mm converter magnetic separation powder accounts for 10%, 5-10 mm converter magnetic separation powder accounts for 65%, 10-15 mm converter magnetic separation powder accounts for 8%, and >15 mm converter magnetic separation powder accounts for 7%. The iron grade of the converter magnetic powder is 65%, and the average phosphorus content of the converter magnetic powder is 0.8%. The phosphorus element of each particle size is obtained according to the fitting curve obtained in Example 1: the phosphorus content of the 0-2mm converter magnetic powder is 1.0002%, the phosphorus content of the 2-5mm converter magnetic powder is 0.6112%, the phosphorus content of the 5-10mm converter magnetic powder is 0.6936%, the phosphorus content of the 10-15mm converter magnetic powder is 1.0134%, and the phosphorus content of the converter magnetic powder>15mm is 1.5202%.

[0063] (3) The phosphorus content of the sintered mixed material without adding magnetic separation powder is 0.065%. After adding the converter magnetic separation powder, the phosphorus content of the sintered mixed material is 0.071%, the phosphorus content of the sintered ore is 0.0674%, and the phosphorus content of the blast furnace iron is 0.115%, which meets the requirement of P < 0.12% in the process regulations and has no effect on the next process.

[0064] Example 6

[0065] This embodiment provides a method for sintering magnetic separation powder, and the specific steps are as follows:

[0066] (1) The converter slag is hot-stemmed and magnetically separated to recover slag steel, and then the remaining slag is rod-milled (specific parameters are motor power 500 kW, motor speed 740 r / min, voltage 10000 V, frequency 53 Hz) to obtain slag with five particle size distributions: 0-2 mm slag accounts for 10%, 2-5 mm slag accounts for 10%, 5-10 mm slag accounts for 65%, 10-15 mm slag accounts for 10%, and >15 mm slag accounts for 5%.

[0067] (2) The steel slag obtained in step (1) is subjected to magnetic separation, and the frequency of the magnetic separation double magnetic drum is 45Hz, and magnetic separation powders with five particle size distributions are obtained, namely, 0-2mm converter magnetic separation powder accounts for 10%, 2-5mm converter magnetic separation powder accounts for 8%, 5-10mm converter magnetic separation powder accounts for 68%, 10-15mm converter magnetic separation powder accounts for 7%, and >15mm converter magnetic separation powder accounts for 7%. The iron grade of the converter magnetic separation powder is 60%, and the average phosphorus content of the converter magnetic separation powder is 0.9%. The phosphorus element of each particle size is obtained according to the fitting curve obtained in Example 1: the phosphorus content of the 0-2mm converter magnetic separation powder is 1.1251%, the phosphorus content of the 2-5mm converter magnetic separation powder is 0.6867%, the phosphorus content of the 5-10mm converter magnetic separation powder is 0.7813%, the phosphorus content of the 10-15mm converter magnetic separation powder is 1.1392%, and the phosphorus content of the >15mm converter magnetic separation powder is 1.7076%.

[0068] (3) The phosphorus content of the sintered mixed material without adding magnetic separation powder is 0.065%. After adding the converter magnetic separation powder, the phosphorus content of the sintered mixed material is 0.073%, the phosphorus content of the sintered ore is 0.0693%, and the phosphorus content of the blast furnace iron is 0.119%, which meets the requirement of P < 0.12% in the process regulations and has no effect on the next process.

[0069] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for sintering magnetic powder, characterized in that: include: Obtain magnetic separation powder of different particle sizes; Obtain the phosphorus content of magnetic separation powder of each particle size; Under the condition that all parameters of sintered ore meet the production requirements, the priority of adding magnetic separation powder of different particle sizes to the sintered mixed material instead of ore powder is adjusted according to the surplus phosphorus load of the sintered ore and the phosphorus content of magnetic separation powder of each particle size.

2. The method for sintering magnetic powder according to claim 1, characterized in that: The iron grade of the magnetic separation powders of different particle sizes is 55-65%.

3. The method for sintering magnetic powder according to claim 1 or 2, characterized in that: The process of obtaining magnetic separation powder of different particle sizes includes: pre-treating steel slag, recovering slag steel by magnetic separation, and rod-milling and magnetic separation of the remaining steel slag.

4. The method for sintering magnetic powder according to claim 3, characterized in that: The pretreatment is hot stewing; And / or, the rod mill processes the remaining slag into: 0-2 mm slag accounts for 5-10%, 2-5 mm slag accounts for 10-15%, 5-10 mm slag accounts for 60-65%, 10-15 mm slag accounts for 5-10%, and >15 mm slag accounts for 0-10%.

5. The method for sintering magnetic powder according to claim 3 or 4, characterized in that: The frequency of the double magnetic rollers in the re-magnetic separation step is 45-50 Hz; And / or, in the re-magnetic separation step, the magnetic separation powder is processed as follows: 0-2mm magnetic separation powder accounts for 0-10%, 2-5mm magnetic separation powder accounts for 5-10%, 5-10mm magnetic separation powder accounts for 65-70%, 10-15mm magnetic separation powder accounts for 10-15%, and >15mm magnetic separation powder accounts for 0-10%.

6. The method for sintering magnetic powder according to claim 5, characterized in that: The phosphorus content of each particle size of the magnetic separation powder is: a1=1.249b+0.001, a2=0.753b+0.009, a3=0.877b-0.008, a4=1.258b+0.007, a5=1.874b+0.021; wherein b is the average phosphorus content of the magnetic separation powder, %; a1-a5 are the phosphorus contents of the magnetic separation powders of five particle sizes of 0-2mm, 2-5mm, 5-10mm, 10-15mm, and >15mm, %.

7. The method for sintering magnetic powder according to claim 5 or 6, characterized in that: The calculation formula for the addition ratio of each particle size of the magnetic separation powder is: Lk=(H1a1+H2a2+H3a3+H4a4+H5a5)-p(H1+H2+H3+H4+H5), wherein L is the phosphorus load of the sintered ore, %; k is the phosphorus content of the sintered mixed material without adding magnetic separation powder, %; H1-H5 are the addition ratios of the five particle sizes of 0-2mm, 2-5mm, 5-10mm, 10-15mm, and >15mm magnetic separation powder in the sintered mixed material, %; p is the average phosphorus content of the ore powder replaced by the magnetic separation powder, %.

8. The method for sintering magnetic separation powder according to any one of claims 5 to 7, characterized in that: The priority of adding the magnetic separation powder to the sintering mixed material is (2-5mm)>(5-10mm)>(0-2mm)>(10-15mm)>(>15mm).

9. The method for sintering magnetic separation powder according to any one of claims 1 to 8, characterized in that: The mineral powder is at least one of Indian powder, Jinbuba powder, Australian PB powder, Yangdi powder, FMG super special powder, FMG mixed powder, Robe River powder, Meishan fine powder and returned ore.

10. The method for sintering magnetic separation powder according to any one of claims 1 to 9, characterized in that: When the sum of the proportions of the magnetic separation powders of various particle sizes is ≤0.5%, no magnetic separation powder is added to the sintered mixed material.

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