Method for extracting iron and reducing impurities from vanadium-titanium-iron concentrate

Abstract

The invention discloses a method for extracting iron and reducing impurities from vanadium-titanium-iron concentrate, and belongs to the technical field of mineral separation. In order to achieve the purpose of extracting iron and reducing impurities from vanadium-titanium-iron concentrate, the invention provides a method for extracting iron and reducing impurities from vanadium-titanium-iron concentrate. The vanadium-titanium-iron ore concentrate is subjected to iron extraction and impurity reduction treatment through the processes of demagnetizing, screening and grading, coarse grain closed-circuit tower grinding and magnetic separation, fine grain direct magnetic separation, coarse grain and fine grain magnetic separation concentrate mixing demagnetizing closed-circuit sand grinding and magnetic separation, magnetic separation concentrate reverse flotation and magnetic separation flotation tailing mixing magnetic separation scavenging. And reverse flotation is optimized, the content of intergrowth of titanomagnetite and gangue minerals in the concentrate is reduced, the high-grade vanadium-titanium-iron concentrate with the TFe increasing amplitude being large is obtained, the TFe grade is increased to 58.12%-61.12%, and the increasing amplitude reaches 4.63%-5.07%.

Description

Technical Field

[0001] The invention belongs to the technical field of ore dressing, and in particular relates to a method for increasing iron content and reducing impurities in vanadium-titanium iron concentrate. Background Art

[0002] Vanadium-titanium magnetite is an important iron ore resource in my country, mainly distributed in the Panzhihua area. Affected by the mineralization conditions, the Panzhihua vanadium-titanium magnetite resources are generally characterized by "poor, fine and mixed". The vanadium-titanium iron concentrate TFe grade produced by the traditional crushing + two-stage grinding and selection process is only 53%-56% (there are obvious differences in different mining areas), which is quite different from the iron concentrate produced by ordinary iron ore. As a result, the fuel consumption of vanadium-titanium iron concentrate is relatively large during the smelting process, which is not conducive to the low-carbon development of the enterprise. Improving the TFe grade of vanadium-titanium iron concentrate is an important measure to reduce smelting fuel. At present, the quality improvement process of Panxi vanadium-titanium iron ore concentrate is the traditional "classification + tower grinding + magnetic separation" process, and the TFe improvement rate is only 1.5-2 percentage points. Due to the insufficient dissociation degree of coarse-grained gangue minerals during grinding, the monomer titanium magnetite is continuously ground. There are still a large number of coarse-fine gangue conjoined bodies, gangue monomers and fine-grained ore slimes in the upgraded concentrate, which seriously affects the TFe grade of the upgraded concentrate and increases the energy consumption of separation and the comprehensive cost of quality improvement.

[0003] CN117960413A discloses a method for deep quality improvement of vanadium-titanium-iron concentrate, comprising the following steps: 1) subjecting the vanadium-titanium-iron concentrate to a first screening operation to obtain a first screened material and a first screened material; 2) subjecting the first screened material to a first grinding operation and then to a first cyclone operation to obtain a first overflow and a first sand settling, subjecting the first screened material to a first quality improvement roughing operation to obtain a first concentrate and a first tailing, subjecting the first concentrate to a second screening operation to obtain a second screened material and a second screened material; 3) subjecting the first overflow to a third screening operation to obtain a third screened material and a third screened material, subjecting the second screened material to a second cyclone operation to obtain a second overflow. and second sand settling; 4) the second oversize, the third oversize and the second overflow are mixed for two-stage grinding and then for the third cyclone operation to obtain the third overflow and the third sand settling, the third overflow is subjected to the third quality upgrading and roughing operation to obtain the third concentrate and the third tailings, and the third undersize is subjected to the second quality upgrading and roughing operation to obtain the second concentrate and the second tailings; 5) the second concentrate and the third concentrate are mixed and mixed with the second sand settling, and then the quality upgrading and concentrating operation is carried out to obtain the concentrating concentrate and the concentrating tailings, and the first tailings, the second tailings, the third tailings and the concentrating tailings are mixed and then the quality upgrading and scavenging operation is carried out to obtain the scavenging concentrate and the scavenging tailings. However, there are still a large number of poor intergrowths of titanomagnetite in the quality-improved concentrate obtained by this method, and the gangue minerals in the concentrate have not been thoroughly discarded, so the TFe grade of the quality-improved concentrate is relatively low, only 3.23 to 3.40 percentage points, which affects the quality of the quality-improved vanadium-titanium-iron concentrate.

[0004] CN105498929A discloses a process for improving the quality and reducing impurities of magnetite concentrate, comprising the following specific steps: (1) wet grinding: a vertical spiral grinding and agitating machine is used to wet grind coarse concentrate ore particles with a grade of less than or equal to 60% and -200 mesh accounting for 60% to 75%, the grinding medium uses small-diameter steel balls with a volume filling rate of 55% to 65%, the mill adopts continuous feeding, the feeding amount is 30 t / h to 50 t / h on a dry basis, the feed weight percentage concentration is 40% to 60%, the stirring spiral speed is controlled at 30 r / min to 50 r / min, and a primary slurry is obtained after grinding for a period of time, and the slurry concentration is controlled at 40% to 60%; (2) primary classification: the primary slurry is discharged into a slurry pool, and the primary slurry is pumped to a hydrocyclone by a slurry pump with a conveying capacity of 200m 3 / h~600m 3 / h, the hydrocyclone classifies the primary slurry, and the classification and sedimentation return to the above step (1), overflowing the secondary slurry; (3) Secondary classification: the secondary slurry enters the drum magnetic separator, the drum speed is controlled at 15r / min~25r / min, and weak magnetic separation is performed to obtain an iron concentrate with a grade of more than 63.5%. However, the beneficiation object of this method is ordinary magnetite, and it is not suitable for vanadium-titanium magnetite of different minerals. Summary of the invention

[0005] In order to solve the problems of the prior art, the present invention reduces the total amount of ore entering the mill for quality improvement, improves the dissociation degree of main metal minerals in the vanadium-titanium-iron concentrate, reduces the inclusion of gangue mineral monomers and ore mud in the concentrate, and reduces the content of lean intergrowths, thereby achieving the purpose of increasing iron and reducing impurities in the vanadium-titanium-iron concentrate.

[0006] The present invention provides a method for extracting iron and reducing impurities in vanadium-titanium iron concentrate, which comprises the following steps:

[0007] A. After demagnetization I, the vanadium-titanium iron concentrate is sieved and graded using 325 mesh I to obtain an oversize I and an undersize I;

[0008] B. subjecting the undersize material I to magnetic roughing separation I to obtain concentrate I and tailings I;

[0009] C. The oversize material I is subjected to a first-stage grinding, and the grinding concentration of the first-stage grinding is controlled to be 60% to 70%. The first-stage grinding product is screened and graded using 400 meshes II to obtain oversize material II and undersize material II. The oversize material II is returned to the first-stage grinding to form a closed-circuit grinding, and the undersize material II is subjected to magnetic roughing II to obtain concentrate II and tailings II;

[0010] D. After the concentrate I and concentrate II are mixed, demagnetization II is carried out, and then the second stage grinding is carried out. The grinding concentration of the second stage grinding is controlled to be 45% to 55%. The second stage grinding product is classified by a cyclone to obtain overflow and sediment. The sediment is returned to the second stage grinding to form a closed-circuit grinding. The overflow is subjected to magnetic separation to obtain concentrate III and tailings III;

[0011] E. Demagnetize concentrate III, and then perform reverse flotation. During reverse flotation, add NaOH to adjust the pH of the system to 11-11.5, add 330-350 g / t of modified starch, and add 100-120 g / t of mixed collector PYY-1 to obtain concentrate IV and tailings IV. Concentrate IV is the final product of improved quality and reduced impurities, which is an improved iron concentrate;

[0012] F. After tailings I, II, III and IV are mixed, magnetic separation and scavenging are carried out to obtain scavenging concentrate and scavenging tailings. The scavenging concentrate is used as sub-iron concentrate and the scavenging tailings is used as quality-enhanced tailings.

[0013] Wherein, in the above-mentioned method for extracting iron and reducing impurities in vanadium-titanium iron concentrate, in step B, the magnetic separation intensity of the magnetic roughing separation I is 2500-3000 Oe.

[0014] Among them, in the above-mentioned method for extracting iron and reducing impurities in vanadium-titanium iron concentrate, in step C, the fineness of the screen material II is -400 mesh, accounting for not less than 95%.

[0015] Wherein, in the above-mentioned method for extracting iron and reducing impurities in vanadium-titanium iron concentrate, in step C, the magnetic separation intensity of the magnetic roughing separation II is 2500-3000 Oe.

[0016] Among them, in the above-mentioned method for extracting iron and reducing impurities in vanadium-titanium iron concentrate, in step D, the fineness of the overflow is -400 mesh, accounting for more than 90%.

[0017] Wherein, in the above-mentioned method for extracting iron and reducing impurities in vanadium-titanium iron ore concentrate, in step D, the magnetic separation intensity of the magnetic separation is 1800-2300 Oe.

[0018] Wherein, in the above method for extracting iron and reducing impurities in vanadium-titanium iron ore concentrate, in step F, the magnetic separation intensity of the magnetic separation is 2800-3300 Oe.

[0019] Among them, in the method for increasing iron content and reducing impurities in the above-mentioned vanadium-titanium iron concentrate, in step E, the TFe grade of the obtained upgraded iron concentrate is 58.12% to 61.12%, the TiO2 grade is 10.43% to 12.58%, and the V2O5 grade is 0.641% to 0.781%.

[0020] In the present invention, modified starch and PYY-1 are both commonly used mineral processing agents in the art, and PYY-1 is a mixture of xanthate, 2# oil and sodium oleate.

[0021] Beneficial effects of the present invention:

[0022] The present invention adopts the process of "screening + tower mill grinding + magnetic separation" to further grind and dissociate the intergrown minerals in the medium and coarse particles in the vanadium-titanium iron concentrate, and remove them through magnetic separation, and at the same time, the particle size composition of the concentrate is also more concentrated; the iron concentrate obtained by the first-stage magnetic rough separation adopts the quality improvement process of "sand mill grinding + classification + magnetic separation" to further grind and dissociate the intergrown particles in the fine particle size and remove them through magnetic separation, and most of the mixed gangue monomers and fine-grained ore mud are also effectively removed, and the TFe grade of the iron concentrate is further improved; the iron concentrate obtained by magnetic separation is subjected to the impurity reduction process of "demagnetization + reverse flotation" to effectively remove the gangue intergrown bodies and mixed monomer gangue and ore mud in each particle size of the concentrate that have a large specific magnetic susceptibility due to the combination with the strongly magnetic minerals, further reduce the gangue mineral content in the concentrate, and improve the purity of the strongly magnetic minerals and the TFe grade of the iron concentrate.

[0023] The present invention adopts the process flow of "demagnetization-screening and grading-coarse-grained closed-circuit tower grinding magnetic separation-fine-grained direct magnetic separation-coarse-fine-grained magnetic separation concentrate mixed demagnetization closed-circuit sand grinding magnetic separation-magnetic separation concentrate reverse flotation-magnetic separation flotation tailings mixed magnetic separation and scavenging" to carry out iron-reducing and impurity-reducing treatment on vanadium-titanium iron concentrate, thereby reducing the content of titanium magnetite and gangue mineral intergrowth in the concentrate, and obtaining a high-grade vanadium-titanium iron concentrate with a large TFe improvement. The TFe grade of the vanadium-titanium iron concentrate is increased from 53.49% to 56.05% to 58.12% to 61.12%, and the improvement reaches 4.63 to 5.07 percentage points. In addition, the present invention centrally scavenges the tailings products obtained by roughing magnetic separation, fine magnetic separation, and reverse flotation selection, and can obtain inferior iron concentrate separately, thereby reducing the loss of metallic iron minerals in the tailings and improving the recovery rate of iron resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0025] Specifically, a method for extracting iron and reducing impurities in vanadium-titanium iron concentrate comprises the following steps:

[0026] A. Demagnetizing the vanadium-titanium iron concentrate I (using a demagnetizer, and the relevant parameters of demagnetization I are conventional parameters in the art), and then screening and grading I (using a screening machine) with 325 mesh to obtain an oversize I and an undersize I;

[0027] B. subjecting the undersize material I to magnetic roughing separation I (using a magnetic separator) to obtain concentrate I and tailings I;

[0028] C. The oversize material I is subjected to a first-stage grinding (using a tower mill), the first-stage grinding controls the grinding concentration to be 60% to 70%, the first-stage grinding product is screened and graded using 400 meshes II (using a screening machine) to obtain oversize material II and undersize material II, the oversize material II is returned to the first-stage grinding to form a closed-circuit grinding (the same stage grinding operation is continuous, the oversize material I and the oversize material II are simultaneously fed into the tower mill to form a closed-circuit grinding), the undersize material II is subjected to a magnetic roughing selection II (using a magnetic separator) to obtain a concentrate II and a tailings II;

[0029] D. After the concentrate I and concentrate II are mixed, demagnetization II is carried out (a high-frequency demagnetizer is used, and the relevant parameters of demagnetization II are conventional parameters in this field), and then two-stage grinding is carried out (a horizontal sand mill is used). The grinding concentration of the second-stage grinding is controlled to be 45% to 55%. The second-stage grinding product is classified by a cyclone to obtain overflow and sedimentation. The sedimentation is returned to the second-stage grinding to form a closed-circuit grinding (the same stage grinding operation is continuous, and the concentrate I, concentrate II and sedimentation are simultaneously fed into the horizontal sand mill to form a closed-circuit grinding). The overflow is subjected to magnetic separation (a magnetic separator is used) to obtain concentrate III and tailings III;

[0030] E. Demagnetize concentrate III (using a demagnetizer, and the relevant parameters of demagnetization III are conventional parameters in the field), and then perform reverse flotation (using a flotation machine). During reverse flotation, NaOH is added to adjust the pH of the system to 11-11.5, and modified starch is added at 330-350 g / t, and mixed collector PYY-1 is added at 100-120 g / t to obtain concentrate IV and tailings IV. Concentrate IV is the final product of quality improvement and impurity reduction, which is an upgraded iron concentrate;

[0031] F. After tailings I, II, III and IV are mixed, magnetic separation and scavenging are carried out (using a magnetic separator) to obtain scavenging concentrate and scavenging tailings. The scavenging concentrate is used as sub-iron concentrate, and the scavenging tailings are used as quality-enhanced tailings.

[0032] In steps A to C of the present invention, the process of "screening + tower mill grinding + magnetic separation" is used to further grind and dissociate the intergrown minerals in the medium and coarse particles in the vanadium-titanium iron concentrate, and then discard them through magnetic separation, which also makes the particle size composition of the concentrate more concentrated. In step A, demagnetization I is first carried out, which is beneficial to improve the screening efficiency, and then screening is carried out with a standard sieve hole of 325 mesh. In step B, the magnetic separation intensity of the magnetic roughing I is 2500-3000Oe. In step C, the fineness of the undersize II is -400 mesh, accounting for not less than 95%. In step C, the magnetic separation intensity of the magnetic roughing II is 2500-3000Oe.

[0033] In step D of the present invention, the iron concentrate obtained by the first stage of magnetic roughing is subjected to the "sand grinding + classification + magnetic separation" quality improvement process to further grind and dissociate the intergrown particles in the fine particle size and remove them by magnetic separation, and most of the mixed gangue monomers and fine-grained ore mud are also effectively removed, further improving the TFe grade of the iron concentrate. In step D, the fineness of the overflow is -400 mesh, accounting for more than 90%. In step D, the magnetic separation intensity of the magnetic separation is 1800-2300Oe.

[0034] Magnetic separation cannot effectively remove the gangue minerals and the intergrowths of strong magnetic minerals such as titanium magnetite in the vanadium-titanium iron concentrate. Therefore, in step E of the present invention, the iron concentrate obtained by magnetic separation is subjected to a "demagnetization + reverse flotation" impurity reduction process to effectively remove the gangue intergrowths and the mixed monomer gangue and ore mud in each particle size of the concentrate due to the intergrowth with the strong magnetic minerals, further reducing the gangue mineral content in the concentrate, and improving the purity of the strong magnetic minerals and the TFe grade of the iron concentrate. In step E, the TFe grade of the obtained upgraded iron concentrate is 58.12% to 61.12%, the TiO2 grade is 10.43% to 12.58%, and the V2O5 grade is 0.641% to 0.781%.

[0035] In step F of the present invention, the tailings products obtained by roughing magnetic separation, fine magnetic separation and reverse flotation separation are scavenged and separated to obtain secondary iron concentrate separately, thereby reducing the loss of metallic iron minerals in the tailings and improving the recovery rate of iron resources. In step F, the magnetic separation intensity of the magnetic separation scavenging is 2800 to 3300 Oe.

[0036] The present invention is further described in detail below by way of examples, but the protection scope of the present invention is not limited to the scope of the examples.

[0037] Example 1

[0038] The vanadium-titanium-iron concentrate sample comes from Panxi vanadium-titanium-iron concentrate production enterprise A, and its chemical composition is shown in Table 1 below.

[0039] Table 1 Chemical composition analysis results of vanadium-titanium iron concentrate sample of Example 1 / wt%

[0040] Analyze Project TFe FeO <![CDATA[TiO2]]> <![CDATA[V2O5]]> <![CDATA[SiO2]]> CaO MgO <![CDATA[Al2O3]]> content 56.05 31.78 10.05 0.712 4.33 0.65 3.24 3.73

[0041] Implementation steps:

[0042] A. After the existing vanadium-titanium iron concentrate is demagnetized by a demagnetizer I, a screening machine with a sieve size of 325 mesh is used for screening and grading I to obtain a +325 mesh oversize I and a -325 mesh undersize I;

[0043] B. The undersize material I is subjected to magnetic roughing separation I by a magnetic separator with a field strength of 3000 Oe to obtain concentrate I and tailings I;

[0044] C. Feed the oversize material I into the tower mill, and carry out a first-stage grinding under the condition of grinding concentration of about 67%. The grinding product is screened and graded by a 400-mesh screener II to obtain a +400-mesh oversize material II and a -400-mesh undersize material II. The particle size of the undersize material II is controlled to be -400 mesh, accounting for 96%. The oversize material II is returned to the tower mill to form a closed-circuit grinding. The undersize material II is subjected to magnetic separation and roughing II by a magnetic separator with a field strength of 3000Oe to obtain concentrate II and tailings II.

[0045] D. After the concentrate I and concentrate II are mixed, the high-frequency demagnetizer is used to demagnetize II, and then the concentrate is fed into a horizontal sand mill for secondary grinding at a grinding concentration of about 52%. The grinding product is classified by a cyclone to obtain overflow and sediment. The overflow particle size is controlled to be about -400 mesh, accounting for about 93%. The sediment is returned to the horizontal sand mill to form a closed-circuit grinding. The overflow is fed into a magnetic separator with a field strength of 2000Oe for magnetic separation and concentration to obtain concentrate III and tailings III;

[0046] E. Demagnetize concentrate III with a high-frequency demagnetizer, and then feed it into a flotation machine for reverse flotation. During reverse flotation, add NaOH to adjust the pH value to 11, add 350g / t of modified starch, and add 120g / t of mixed collector PYY-1 to obtain concentrate IV and tailings IV. Concentrate IV is used as the final product of quality improvement and impurity reduction to improve the quality of iron concentrate;

[0047] F. After tailings I, II, III and IV are mixed, they are fed into a magnetic separator with a field strength of 3000Oe for magnetic separation and scavenging. The scavenged concentrate is used as the secondary iron concentrate, and the scavenged tailings are used as the quality-enhanced tailings.

[0048] The results show that the chemical composition analysis results of the upgraded vanadium-titanium iron concentrate, secondary iron concentrate and upgraded tailings finally obtained by this process are shown in Table 2 below.

[0049] Table 2 Chemical composition analysis results of the upgraded product of vanadium-titanium iron concentrate in Example 1 / wt%

[0050]

[0051]

[0052] Example 2

[0053] The vanadium-titanium-iron concentrate sample comes from Panxi vanadium-titanium-iron concentrate production enterprise B, and its chemical composition is shown in Table 3 below.

[0054] Table 3 Chemical composition analysis results of vanadium-titanium iron concentrate sample of Example 2 / wt%

[0055] Analyze Project TFe FeO <![CDATA[TiO2]]> <![CDATA[V2O5]]> <![CDATA[SiO2]]> CaO MgO <![CDATA[Al2O3]]> content 53.49 30.87 13.07 0.588 1.13 2.89 3.85 53.19

[0056] Implementation steps:

[0057] A. After the existing vanadium-titanium iron concentrate is demagnetized by a demagnetizer I, a screening machine with a sieve size of 325 mesh is used for screening and grading I to obtain a +325 mesh oversize I and a -325 mesh undersize I;

[0058] B. The undersize material I is subjected to magnetic roughing separation I by a magnetic separator with a field strength of 3000 Oe to obtain concentrate I and tailings I;

[0059] C. Feed the oversize material I into the tower mill, and carry out a first-stage grinding under the condition of grinding concentration of about 62%. The grinding product is screened and graded by a 400-mesh screener II to obtain a +400-mesh oversize material II and a -400-mesh undersize material II. The particle size of the undersize material II is controlled to be -400 mesh, accounting for 95%. The oversize material II is returned to the tower mill to form a closed-circuit grinding. The undersize material II is subjected to magnetic separation and roughing II by a magnetic separator with a field strength of 3000Oe to obtain concentrate II and tailings II.

[0060] D. After the concentrate I and concentrate II are mixed, the high-frequency demagnetizer is used to demagnetize II, and then the concentrate is fed into a horizontal sand mill for two-stage grinding at a grinding concentration of about 46%. The grinding product is classified by a cyclone to obtain overflow and sediment. The overflow particle size is controlled to be about -400 mesh, accounting for about 91%. The sediment is returned to the horizontal sand mill to form a closed-circuit grinding. The overflow is fed into a magnetic separator with a field strength of 2000Oe for magnetic separation and concentration to obtain concentrate III and tailings III;

[0061] E. Demagnetize concentrate III with a high-frequency demagnetizer, and then feed it into a flotation machine for reverse flotation. During reverse flotation, add NaOH to adjust the pH value to 11.5, add 330g / t of modified starch, and add 100g / t of mixed collector PYY-1 to obtain concentrate IV and tailings IV. Concentrate IV is used as the final product of quality improvement and impurity reduction to improve the quality of iron concentrate;

[0062] F. After tailings I, II, III and IV are mixed, they are fed into a magnetic separator with a field strength of 3000Oe for magnetic separation and scavenging. The scavenged concentrate is used as the secondary iron concentrate, and the scavenged tailings are used as the quality-enhanced tailings.

[0063] The results show that the chemical composition analysis results of the upgraded vanadium-titanium iron concentrate, secondary iron concentrate and upgraded tailings finally obtained by this process are shown in Table 4 below.

[0064] Table 4 Chemical composition analysis results of the upgraded product of vanadium-titanium iron concentrate in Example 2 / wt%

[0065]

[0066]

[0067] From the above, it can be seen that the present invention optimizes the grinding, grading and magnetic separation process and parameters in the process of upgrading the vanadium-titanium iron concentrate, increases the reverse flotation operation, strengthens the ejection rate of the gangue minerals and titanomagnetite in the vanadium-titanium iron concentrate, and further increases the proportion of titanomagnetite in the upgraded vanadium-titanium iron concentrate. The TFe grade of the vanadium-titanium iron concentrate is increased from 53.49% to 56.05% to 58.12% to 61.12%, the TFe increase is 4.63 to 5.07 percentage points, and the TFe recovery rate is 92.72% to 93.62%.

Claims

1. A method for increasing iron content and reducing impurities in vanadium-titanium iron concentrate, characterized by: The following steps are involved: A. After demagnetization I, the vanadium-titanium iron concentrate is sieved and graded using 325 mesh I to obtain an oversize I and an undersize I; B. subjecting the undersize material I to magnetic roughing separation I to obtain concentrate I and tailings I; C. The oversize material I is subjected to a first-stage grinding, and the grinding concentration of the first-stage grinding is controlled to be 60% to 70%. The first-stage grinding product is screened and graded using 400 meshes II to obtain oversize material II and undersize material II. The oversize material II is returned to the first-stage grinding to form a closed-circuit grinding, and the undersize material II is subjected to magnetic roughing II to obtain concentrate II and tailings II; D. After the concentrate I and concentrate II are mixed, demagnetization II is carried out, and then the second stage grinding is carried out. The grinding concentration of the second stage grinding is controlled to be 45% to 55%. The second stage grinding product is classified by a cyclone to obtain overflow and sediment. The sediment is returned to the second stage grinding to form a closed-circuit grinding. The overflow is subjected to magnetic separation to obtain concentrate III and tailings III; E. Demagnetize concentrate III, and then perform reverse flotation. During reverse flotation, add NaOH to adjust the pH of the system to 11-11.5, add 330-350 g / t of modified starch, and add 100-120 g / t of mixed collector PYY-1 to obtain concentrate IV and tailings IV. Concentrate IV is the final product of improved quality and reduced impurities, which is an improved iron concentrate; F. After tailings I, II, III and IV are mixed, magnetic separation and scavenging are carried out to obtain scavenging concentrate and scavenging tailings. The scavenging concentrate is used as sub-iron concentrate and the scavenging tailings is used as quality-enhanced tailings.

2. The method for increasing iron content and reducing impurities in vanadium-titanium iron concentrate according to claim 1, characterized in that: In step B, the magnetic separation intensity of the rough magnetic separation I is 2500-3000 Oe.

3. The method for increasing iron content and reducing impurities in vanadium-titanium iron concentrate according to claim 1, characterized in that: In step C, the fineness of the undersize II is -400 mesh, accounting for no less than 95%.

4. The method for increasing iron content and reducing impurities in vanadium-titanium iron concentrate according to claim 1, characterized in that: In step C, the magnetic separation intensity of the rough magnetic separation II is 2500 to 3000 Oe.

5. The method for increasing iron content and reducing impurities in vanadium-titanium iron concentrate according to claim 1, characterized in that: In step D, the fineness of the overflow is -400 mesh, accounting for more than 90%.

6. The method for increasing iron content and reducing impurities in vanadium-titanium iron concentrate according to claim 1, characterized in that: In step D, the magnetic separation intensity of the magnetic separation is 1800 to 2300 Oe.

7. The method for increasing iron content and reducing impurities in vanadium-titanium iron concentrate according to claim 1, characterized in that: In step F, the magnetic separation intensity of the magnetic separation is 2800-3300 Oe.

8. The method for extracting iron and reducing impurities in vanadium-titanium iron concentrate according to any one of claims 1 to 7, characterized in that: In step E, the TFe grade of the upgraded iron ore concentrate obtained is 58.12% to 61.12%, the TiO2 grade is 10.43% to 12.58%, and the V2O5 grade is 0.641% to 0.781%.

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