Method for producing vanadium-containing pig iron by using low-vanadium steel slag

Abstract

The invention discloses a method for producing vanadium-containing pig iron by using low-vanadium steel slag, and belongs to the technical field of comprehensive utilization of metallurgical slag. According to the production method, the vanadium-containing magnetite is pretreated to obtain vanadium-containing magnetite powder, then the vanadium-containing magnetite powder and the liquid steel slag react under the oxygen condition to obtain an intermediate reaction material, and phosphorus is repeatedly added into the intermediate reaction material to enable iron ions and vanadium ions to be fully reduced, so that the vanadium-containing pig iron is obtained. The vanadium-containing pig iron produced through the method is high in vanadium content, and the slag and the vanadium-containing pig iron can be completely separated through the specific gravity difference.

Description

Technical Field

[0001] The present invention belongs to the technical field of comprehensive utilization of metallurgical slag, and particularly relates to a method for producing vanadium-containing pig iron by using low-vanadium steel slag. Background Art

[0002] The vanadium resources in the Panxi region mainly exist in vanadium-bearing magnetite. Through the unique converter vanadium extraction and steelmaking process of Pangang, the precious resource vanadium has been effectively extracted, but there is still a small amount of vanadium resources in the liquid steel slag; the V 2 O 5 content in the produced liquid steel slag is maintained at 0.8-1.2%, and the recovery of vanadium is difficult. At present, only part of the iron-containing liquid steel slag is applied to blast furnaces or submerged arc furnaces in the form of recovering iron-containing resources, but a large amount of tail slag and tail powder have not been well utilized, resulting in serious waste of vanadium resources. Therefore, developing a more efficient vanadium extraction technology for liquid steel slag is of great significance for the utilization of vanadium resources in the Panxi region and even the whole country. Summary of the Invention

[0003] In view of the above-mentioned prior art, the present invention discloses a method for producing vanadium-containing pig iron by using low-vanadium steel slag to solve the technical problem of low vanadium extraction recovery rate from liquid steel slag in the prior art.

[0004] The technical solution adopted to solve its technical problem is to provide a method for producing vanadium-containing pig iron by using low-vanadium steel slag, which includes the following steps:

[0005] S1: Crushing, grinding, sieving and drying the vanadium-bearing magnetite to obtain vanadium-bearing magnetite powder;

[0006] S2: Mixing the vanadium-bearing magnetite powder and liquid steel slag, and reacting under oxygen conditions to obtain an intermediate reaction material;

[0007] S3: Adding elemental phosphorus accounting for 1.5-2.0% of the mass of the intermediate reaction material to the intermediate reaction material, and carrying out a reduction reaction under vacuum conditions. After the reaction is completed, the reaction gas is evacuated;

[0008] S4: Repeating step S3 for 3-5 times, and separating to obtain vanadium-containing pig iron.

[0009] On the basis of the above technical solution, the present invention can be further improved as follows.

[0010] Further, the composition of the vanadium-bearing magnetite in step S1 includes 22-25 wt% FeO, 18-20 wt% Fe 2 O 3 , 22-25 wt% SiO 2 , 0.1-0.5 wt% V 2 O 5 and 6-8 wt% CaO.

[0011] Furthermore, the sieve size for sieving in step S1 is 3 mm; the water content in the vanadium-bearing magnetite powder is < 2.0%.

[0012] Furthermore, the liquid steel slag in step S2 is the steel slag obtained from converter steelmaking, and the composition of the liquid steel slag includes 30 - 50 wt% Ca 2 SiO 4 , 15 - 25 wt% Ca(FeO 2 ) 2 and 5 - 15 wt% Ca 3 (VO 4 ) 2 .

[0013] Furthermore, the mass ratio of the vanadium-bearing magnetite powder to the liquid steel slag in step S2 is 0.2 - 0.3:1.

[0014] Furthermore, the reaction time in step S2 is 15 - 20 min.

[0015] Furthermore, the intermediate reaction material components in step S2 include 50 - 60 wt% Ca(FeO 2 ) 2 and 10 - 15 wt% Ca(VO 3 ) 2 .

[0016] Furthermore, the reduction reaction temperature in step S3 is 1500 - 1600 °C, and the reduction reaction time is 30 - 40 min.

[0017] The present invention has the following beneficial effects:

[0018] 1. Promote the component reaction of low-vanadium steel slag to be converted into Ca(FeO 2 ) 2 and Ca(VO 3 ) 2 with the assistance of vanadium-bearing magnetite and oxygen, and then improve the reduction degrees of iron ions and vanadium ions in Ca(FeO 2 ) 2 and Ca(VO 3 ) 2 through cyclic phosphorus reduction reaction, so as to obtain vanadium-bearing pig iron. The content of V converted into V 2 O 5 in the obtained vanadium-bearing pig iron is 3.0 - 5.0 wt%.

[0019] 2. Improve the reduction reaction effect through cyclic phosphorus reduction reaction for multiple times. After the reaction ends, the slag Ca 3 (PO 4 ) 2It exists in solid form with a specific gravity of 3.14 g / cm 3 , and precipitates at the upper part of the reaction vessel; the specific gravity of iron is 7.87 g / cm 3 , the specific gravity of vanadium is 6.11 g / cm 3 , metallic iron and metallic vanadium exist in the form of vanadium-containing pig iron and precipitate at the bottom of the reaction vessel. The complete separation of slag and vanadium-containing pig iron can be achieved by using the specific gravity difference. Specific embodiments

[0020] The method for producing vanadium-containing pig iron from low-vanadium steel slag is further described in detail below through examples.

[0021] Example 1

[0022] In this example, the components of vanadium magnetite are shown in Table 1; the liquid steel slag is the steel slag formed after converter steelmaking, and its components are shown in Table 2.

[0023] Table 1

[0024] Composition FeO <![CDATA[Fe 2 O 3 > <![CDATA[SiO 2 > <![CDATA[V 2 O 5 > CaO Content (wt%) 22.75 18.41 22.38 0.32 6.81

[0025] Table 2

[0026] Composition <![CDATA[Ca 2 SiO 4 > <![CDATA[Ca(FeO 2 ) 2 > <![CDATA[Ca 3 (VO 4 ) 2 > Content (wt%) 45.27 19.81 7.35

[0027] A method for producing vanadium-containing pig iron from low-vanadium steel slag, the method comprising the following steps:

[0028] S1: The vanadium magnetite is crushed by a crusher, then the vanadium magnetite is ground by a ball mill, and the ground iron ore powder is sieved through a 3 mm sieve, and then the iron ore powder is baked until the moisture content in the iron ore powder is 0.86%, obtaining vanadium magnetite powder;

[0029] S2: The vanadium magnetite powder and the liquid steel slag are added to a reaction tank according to a mass ratio of 0.25:1, and then an oxygen lance is inserted into the liquid steel slag for oxygen blowing and stirring. The insertion depth of the oxygen lance is one-half of the depth of the liquid steel slag, and the oxygen blowing and stirring reaction is carried out for 18 min. During the oxygen blowing and stirring process, 15-20 wt% of FeO is oxidized to Fe 2 O 3 , 30-50 wt% of CaO is converted into Ca(FeO 2 ) 2 , and the following chemical reactions occur:

[0030] 4FeO + O 2 = 2Fe 2 O 3 ;

[0031] CaO + Fe 2 O 3 = Ca(FeO2 ) 2 ;

[0032] After the reaction is completed, transfer the reaction materials to a reaction kettle. The content of Ca(FeO 2 ) 2 in the reaction materials is 58.75 wt%, and the content of Ca(VO 3 ) 2 is 12.36 wt%;

[0033] S3: Add P accounting for 1.8% of the mass of the reaction materials to the reaction kettle under vacuum conditions, and keep the reaction at 1580 - 1600 °C for 32 min. The following chemical reactions occur:

[0034] 15Ca(FeO 2 ) 2 + 18P = 5Ca 3 (PO 4 ) 2 + 30Fe + 4P 2 O 5 ;

[0035] 3Ca(VO 3 ) 2 + 6P = Ca 3 (PO 4 ) 2 + 6V + 2P 2 O 5 ;

[0036] S4: Repeat the reduction reaction in step S3 four times. The relevant parameters of the four reactions are shown in Table 3.

[0037] Table 3

[0038] Number of reactions Proportion of phosphorus added (wt%) Reaction temperature (°C) Reaction time (min) First time 1.6 1560～1580 35 Second time 1.7 1580～1600 36 Third time 1.6 1560～1580 32 Fourth time 1.9 1580～1600 37

[0039] After the reaction is completed, the slag Ca 3 (PO 4 ) 2 exists in solid form, with a specific gravity of 3.14 g / cm 3 , and precipitates at the upper part of the reaction kettle; the specific gravity of Fe is 7.87 g / cm 3 , the specific gravity of V is 6.11 g / cm 3 , Fe and V exist in the form of vanadium-containing pig iron and precipitate at the bottom of the reaction kettle. The content of V converted to V 2 O 5 in the vanadium-containing pig iron is maintained at 4.26 wt%.

[0040] Example 2

[0041] In this embodiment, the vanadium magnetite includes the components as shown in Table 4; the liquid steel slag is the steel slag formed after converter steelmaking, and its components are shown in Table 5.

[0042] Table 4

[0043] Composition FeO <![CDATA[Fe 2 O 3 > <![CDATA[SiO 2 > <![CDATA[V 2 O 5 > CaO Content (wt%) 22.15 18.01 21.88 0.12 6.11

[0044] Table 5

[0045] Composition <![CDATA[Ca 2 SiO 4 > <![CDATA[Ca(FeO 2 ) 2 > <![CDATA[Ca 3 (VO 4 ) 2 > Content (wt%) 30.27 14.91 5.15

[0046] A method for producing vanadium-containing pig iron from low-vanadium steel slag, the method comprising the following steps:

[0047] S1: Use a crusher to crush the vanadium magnetite, then use a ball mill to grind the vanadium magnetite, sieve the ground iron ore powder with a 3 mm sieve, and then bake the iron ore powder until the moisture content in the iron ore powder is 1.5%, to obtain vanadium magnetite powder;

[0048] S2: Add the vanadium magnetite powder and the liquid steel slag into the reaction tank according to a mass ratio of 0.2:1, then insert an oxygen lance into the liquid steel slag to blow oxygen and stir, the insertion depth of the oxygen lance is one-half of the depth of the liquid steel slag, and blow oxygen and stir for 20 min. During the process of blowing oxygen and stirring, 15-20 wt% of FeO is oxidized to Fe 2 O 3 , 30-50 wt% of CaO is converted to Ca(FeO 2 ) 2 , and the following chemical reactions occur:

[0049] 4FeO + O 2 = 2Fe 2 O 3 ;

[0050] CaO + Fe 2 O 3 = Ca(FeO 2 ) 2 ;

[0051] After the reaction is completed, transfer the reaction materials to a reaction kettle. The content of Ca(FeO 2 ) 2 in the reaction materials is 51.75 wt%, and the content of Ca(VO 3 ) 2 is 10.36 wt%;

[0052] S3: Add P accounting for 1.8% of the mass of the reaction materials to the reaction kettle under vacuum conditions, and keep the reaction at 1580-1600 °C for 30 min. The following chemical reactions occur:

[0053] 15Ca(FeO2 ) 2 +18P = 5Ca 3 (PO 4 ) 2 +30Fe + 4P 2 O 5 ;

[0054] 3Ca(VO 3 ) 2 +6P = Ca 3 (PO 4 ) 2 +6V + 2P 2 O 5 ;

[0055] S4: Repeat the reduction reaction in step S3 four times. The relevant parameters for the four reactions are shown in Table 6.

[0056] Table 6

[0057] Number of reactions Proportion of phosphorus added (wt%) Reaction temperature (°C) Reaction time (min) First time 1.6 1560～1580 40 Second time 1.7 1580～1600 36 Third time 1.6 1500～1580 34 Fourth time 1.9 1580～1600 37

[0058] After the reaction, the slag Ca 3 (PO 4 ) 2 exists in solid form with a specific gravity of 3.14 g / cm 3 , and precipitates at the upper part of the reaction kettle; the specific gravity of Fe is 7.87 g / cm 3 , the specific gravity of V is 6.11 g / cm 3 , Fe and V exist in the form of vanadium-containing pig iron and precipitate at the bottom of the kettle. The V content in the vanadium-containing pig iron is maintained at 3.16 wt%. 2 O 5

[0059] Example 3

[0060] In this example, the vanadium magnetite includes the components shown in Table 7; the liquid steel slag is the slag formed after converter steelmaking, and it includes the components shown in Table 8.

[0061] Table 7

[0062]

[0063]

[0064] Table 8

[0065] Composition <![CDATA[Ca 2 SiO 4 > <![CDATA[Ca(FeO 2 ) 2 > <![CDATA[Ca 3 (VO 4 ) 2 > Content (wt%) 50.27 25.01 14.95

[0066] A method for producing vanadium-containing pig iron using low-vanadium steel slag, the method comprising the following steps:

[0067] S1: Use a crusher to crush the vanadium-bearing magnetite, then use a ball mill to grind the vanadium-bearing magnetite, sieve the ground iron ore powder with a 3mm sieve, and then bake the iron ore powder until the moisture content in the iron ore powder is 1%, obtaining vanadium-bearing magnetite powder;

[0068] S2: Add the vanadium-bearing magnetite powder and liquid steel slag into the reaction tank according to a mass ratio of 0.3:1, then insert an oxygen lance into the liquid steel slag for oxygen blowing and stirring. The insertion depth of the oxygen lance is half of the depth of the liquid steel slag, and carry out oxygen blowing and stirring reaction for 18 min. During the oxygen blowing and stirring process, 15 - 20 wt% of FeO is oxidized to Fe 2 O 3 , 30 - 50 wt% of CaO is converted to Ca(FeO 2 ) 2 , and the following chemical reactions occur:

[0069] 4FeO + O 2 = 2Fe 2 O 3 ;

[0070] CaO + Fe 2 O 3 = Ca(FeO 2 ) 2 ;

[0071] After the reaction ends, transfer the reaction materials to a reaction kettle. The content of Ca(FeO 2 ) 2 in the reaction materials is 59.95 wt%, and the content of Ca(VO 3 ) 2 is 15.16 wt%;

[0072] S3: Add P accounting for 2.0% of the mass of the reaction materials into the reaction kettle under vacuum conditions, and keep the reaction at 1500 - 1600 °C for 40 min. The following chemical reactions occur:

[0073] 15Ca(FeO 2 ) 2 + 18P = 5Ca 3 (PO 4 ) 2 + 30Fe + 4P 2 O 5 ;

[0074] 3Ca(VO 3 ) 2 + 6P = Ca 3 (PO 4 ) 2 + 6V + 2P 2 O 5 ;

[0075] S4: Repeat the reduction reaction in step S3 four times. The relevant parameters for the four reactions are shown in Table 9.

[0076] Table 9

[0077]

[0078]

[0079] After the reaction, the slag Ca 3 (PO 4 ) 2 exists in solid form with a specific gravity of 3.14 g / cm 3 , and precipitates at the upper part of the reaction kettle; the specific gravity of Fe is 7.87 g / cm 3 , the specific gravity of V is 6.11 g / cm 3 , Fe and V exist in the form of vanadium-containing pig iron and precipitate at the bottom of the kettle. The content of V converted to V 2 O 5 in the vanadium-containing pig iron is maintained at 5.04 wt%.

[0080] Although the specific implementation modes of the present invention have been described in detail in combination with the embodiments, it should not be construed as a limitation on the protection scope of this patent. Within the scope described in the claims, various modifications and deformations that can be made by those skilled in the art without creative efforts still fall within the protection scope of this patent.

Claims

1. A method for producing vanadium-containing pig iron using low-vanadium steel slag, characterized in that: The following steps are involved: S1: crushing, grinding, sieving and drying the vanadium-containing magnetite to obtain vanadium-containing magnetite powder; S2: mixing the vanadium-containing magnetite powder and liquid steel slag, and reacting them under oxygen conditions to obtain an intermediate reaction material; S3: adding 1.5-2.0% of the weight of the intermediate reaction material to the intermediate reaction material, performing a reduction reaction under vacuum conditions, and extracting the reaction gas after the reaction is completed; S4: Repeat step S3 3 to 5 times to obtain vanadium-containing pig iron after separation.

2. The method for producing vanadium-containing pig iron using low-vanadium steel slag according to claim 1, characterized in that: The composition of the vanadium-containing magnetite in step S1 includes 22-25wt% FeO, 18-20wt% Fe2O3, 22-25wt% SiO2, 0.1-0.5wt% V2O5 and 6-8wt% CaO.

3. The method for producing vanadium-containing pig iron using low-vanadium steel slag according to claim 1, characterized in that: The size of the sieve used in step S1 is 3 mm; the water content in the vanadium-containing magnetite powder is less than 2.0%.

4. The method for producing vanadium-containing pig iron using low-vanadium steel slag according to claim 1, characterized in that: The liquid slag in step S2 is the slag obtained in converter steelmaking, and the composition of the liquid slag includes 30-50wt% Ca2SiO4, 15-25wt% Ca(FeO2)2 and 5-15wt% Ca3(VO4)2.

5. The method for producing vanadium-containing pig iron using low-vanadium steel slag according to claim 1, characterized in that: In step S2, the mass ratio of the vanadium-containing magnetite powder to the liquid steel slag is 0.2-0.3:

1.

6. The method for producing vanadium-containing pig iron using low-vanadium steel slag according to claim 1, characterized in that: The reaction time in step S2 is 15 to 20 minutes.

7. The method for producing vanadium-containing pig iron using low-vanadium steel slag according to claim 1, characterized in that: The intermediate reaction material components in step S2 include 50-60wt% Ca(FeO2)2 and 10-15wt% Ca(VO3)2.

8. The method for producing vanadium-containing pig iron using low-vanadium steel slag according to claim 1, characterized in that: In step S3, the reduction reaction temperature is 1500-1600° C., and the reduction reaction time is 30-40 min.

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