A tailings fine powder and its preparation method

Abstract

The present invention relates to the technical field of solid waste resource treatment, and specifically discloses a tailings fine powder and a preparation method thereof. Through the process of wet grinding - first magnetic separation - wet grinding - second magnetic separation on low-grade vanadium-titanium magnetite, a treated slurry is obtained; further, a flotation reagent is added to the treated slurry for flotation to obtain a flotation slurry, wherein the flotation reagent is a mixture of oleic acid and poly(succinamide); the flotation slurry is flocculated and the moisture content is controlled to be < 3% to obtain a dried product; a grinding aid and a modifier are added to the dried product, and double closed-loop internal circulation grinding is performed to obtain the tailings fine powder, wherein the grinding aid is a mixture of desulfurized gypsum, triethanolamine and calcium oxide powder, and the modifier is a mixture of hydroxyethylidene diphosphonic acid, dodecyltrimethylammonium chloride and triisopropanolamine. The production process of the tailings fine powder provided by the present invention is simple, the material production cost and energy consumption are low, the economic benefit is obvious, and environmental pollution can also be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste resource treatment, and in particular to a tailings fine powder and a preparation method thereof. Background Art

[0002] Vanadium-titanium magnetite belongs to a kind of ultra-poor ore, which is widely distributed in Panzhihua and Chengde areas of China. The iron grade content in the original ore is relatively low, resulting in a large amount of tailings after beneficiation. Therefore, under the existing technical and economic conditions, it is very difficult to further use the waste residues from industrial production such as vanadium-titanium magnetite.

[0003] The existing vanadium-titanium magnetite tailings are mainly used as non-active materials to produce glass products, refractory materials, ceramic products, inorganic artificial marble, and to produce cement clinker and wall materials. However, in these applications, there are often various defects such as unstable quality, too high cost, and easy to cause secondary pollution. The main components of vanadium-titanium magnetite are silicon dioxide and aluminum trioxide. However, due to the large amount of mica and chlorite in vanadium-titanium magnetite, when the vanadium-titanium magnetite is directly ground into a admixture, the water demand is large and the activity is low, making it difficult to directly use as an admixture in concrete. Therefore, it is of great significance to develop a preparation method of modified tailings fine powder to improve the activity of the existing tailings fine powder. Summary of the Invention

[0004] In view of this, in order to solve the problems of low utilization rate and poor activity of the existing tailings fine powder, the present invention provides a tailings fine powder and a preparation method thereof.

[0005] To solve the above technical problems, the technical solution provided by the present invention is:

[0006] A preparation method of a tailings fine powder, comprising the following steps:

[0007] Step a, wet-grind low-grade vanadium-titanium magnetite to obtain a primary pulp; perform a first magnetic separation on the primary pulp to obtain a first selected ore and a first magnetic separation tailing pulp;

[0008] Wherein, the proportion of particles with a fineness of ≥200 meshes in the primary pulp is 25%-40%, and the pulp concentration is 70%-75%;

[0009] Step b, wet-grind the first selected ore to obtain a secondary pulp; perform a second magnetic separation on the secondary pulp to obtain a second selected ore and a second magnetic separation tailing pulp, screen and remove particles with a size of <200 meshes in the first magnetic separation tailing pulp and the second magnetic separation tailing pulp to obtain a treated pulp;

[0010] Wherein, the proportion of the ground fineness of the secondary pulp with a fineness of ≥200 meshes is 60%-80%, and the pulp concentration is 70%-75%;

[0011] Step c: Add flotation reagents to the treated pulp for flotation to obtain a flotation pulp;

[0012] Among them, the flotation reagent is a mixture of oleic acid and poly(succinamide);

[0013] Step d: Add a flocculant to the flotation pulp for flocculation precipitation, stand for separation to obtain upper clear water and lower slurry precipitate; Dry the lower slurry precipitate until the moisture content < 3% to obtain a dried product;

[0014] Step e: Add a grinding aid and a modifier to the dried product, and perform double-closed-loop internal circulation grinding until the Blaine specific surface area of the particles > 450 m 2 / kg to obtain the tailing fine powder;

[0015] Among them, the grinding aid is a mixture of desulfurized gypsum, triethanolamine, and calcium oxide powder; the modifier is a mixture of hydroxyethylidene diphosphonic acid, dodecyltrimethylammonium chloride, and triisopropanolamine.

[0016] The inventor unexpectedly found that by synergistically controlling the pulp concentration, pulp particle size, and specific number of magnetic separation times, the problem of difficult particle separation caused by ultrafine grinding can be effectively solved, and the activity stability of the treated pulp can be improved; By determining the fineness during the grinding of low-grade vanadium-titanium magnetite, the grades of magnetic iron, titanium dioxide, and vanadium pentoxide in the first magnetic separation tailing pulp and the second magnetic separation tailing pulp can be reduced, which is beneficial to the subsequent treatment of the treated pulp. The process of combining two grindings and two magnetic separations can also destroy the stable structures of the Si phase and Al phase in the treated pulp, increase the content of amorphous silica and alumina in the treated pulp, thereby improving the activity of the tailing fine powder; Further adding a specific flotation reagent can effectively separate chlorite and mica in the treated pulp, avoid chlorite and mica from affecting the quality of the tailing fine powder, and thus reduce the water demand ratio of the tailing fine powder; When treating the first magnetic separation tailing pulp and the second magnetic separation tailing pulp, particles with a size < 200 mesh are screened out and can be sold as construction sand products; The present invention also defines a specific grinding aid. Among them, SO4 in the desulfurized gypsum 2- can be adsorbed on A1 3+At the activation point of the network intermediate, the Si-O and Al-O bonds in the Si-O-Al alternating structure are broken, promoting the further dissolution of the aluminum phase, improving the activity of the tailings micro-powder. Triethanolamine can improve the grinding efficiency and further increase the early strength of the concrete doped with the tailings micro-powder. Calcium oxide powder can increase the alkalinity of the system, and the Ca(OH)₂ generated after reacting with water is beneficial to the dissolution of the active Si and Al phases in the tailings micro-powder, further stimulating the activity of the tailings micro-powder. By adding a grinding aid compounded with specific components, the grinding efficiency of the tailings micro-powder can be greatly improved, thereby increasing the specific surface area of the tailings micro-powder, reducing the water demand ratio of the tailings micro-powder, and enhancing the activity of the tailings micro-powder. The present invention further defines that the modifier is a mixture of hydroxyethylidene diphosphonic acid, dodecyl trimethyl ammonium chloride, and triisopropanolamine. Among them, hydroxyethylidene diphosphonic acid can displace the flocculant adsorbed on the surface of the tailings micro-powder, playing a dispersing role; dodecyl trimethyl ammonium chloride can improve the dispersibility of the tailings micro-powder and also enable the active Si phase and active Al phase of the tailings micro-powder to have better contact with the mixing water during the hydration process; triisopropanolamine can improve the movement of Si 4+ 、Al 3+ , improving the activity of the tailings micro-powder; the long-chain group generated after the combination of dodecyl trimethyl ammonium chloride and hydroxyethylidene diphosphonic acid can avoid the problem of difficult treatment of tailings sewage caused by the large degradation difficulty of the flocculant in the follow-up, and can further improve the dispersibility of the tailings micro-powder during use. Through the synergistic effect of hydroxyethylidene diphosphonic acid, dodecyl trimethyl ammonium chloride, and triisopropanolamine, not only the grinding level of the tailings micro-powder is improved, but also the Si and Al phases in the tailings micro-powder are stimulated, thereby enhancing the activity of the tailings micro-powder and further reducing the water demand ratio.

[0017] Preferably, in step a, the magnetic separation intensity of the first magnetic separation is 4000 Gs - 4500 Gs.

[0018] Preferably, in step b, the magnetic separation intensity of the second magnetic separation is 2800 Gs - 3200 Gs.

[0019] Preferably, in step a, the mass content of magnetic iron in the low-grade vanadium-titanium magnetite is < 20%, the mass content of silicon dioxide is 30% - 50%, and the mass content of aluminum oxide is 10% - 20%.

[0020] Preferably, in step c, the mass ratio of oleic acid to poly(succinamic acid) in the flotation reagent is 5 - 6:1.

[0021] The preferred flotation reagent is beneficial to the separation of chlorite and mica, avoiding the influence of mica and chlorite on the quality of the tailings micro-powder and reducing the water demand ratio of the tailings micro-powder.

[0022] Preferably, the molecular weight of the poly(succinamic acid) is 5000 - 20000.

[0023] Preferably, in step c, the addition amount of the flotation reagent is 1‰-2‰ of the mass of the treated pulp.

[0024] The addition amount of the preferably flotation reagent is beneficial to reducing the water demand ratio of the tailing fine powder.

[0025] Preferably, in step d, the addition amount of the flocculant is 2‰-3‰ of the mass of the floated pulp.

[0026] It should be further noted that in step d, the lower-layer mud precipitate is discharged from the lower pipeline of the sedimentation tank to obtain a mud precipitate with a water content of 30%-60%. The mud precipitate is processed by a filter or a filter press to a water content of 8%-10% to obtain a filter cake. During the transportation of the filter cake on the belt, it is dried by a dryer to make the water content <3% to obtain a dried product.

[0027] Preferably, in step d, the flocculant is anionic polyacrylamide.

[0028] Preferably, in step e, the mass ratio of desulfurized gypsum, triethanolamine and calcium oxide powder in the grinding aid is 5-5.2:0.01-0.03:5-5.2.

[0029] The preferably grinding aid can further improve the grinding efficiency of the tailing fine powder, thereby improving the activity of the tailing fine powder.

[0030] Preferably, in step e, the addition amount of the grinding aid is 9%-11% of the mass of the dried product.

[0031] Preferably, the sulfur content in the desulfurized gypsum is 35%-50%.

[0032] It should be further noted that the addition method of the desulfurized gypsum is: adding from the feed port of the grinder; the addition method of the calcium oxide powder is: feeding from the mill port through the pneumatic conveying pipeline.

[0033] Preferably, in step e, the mass ratio of hydroxyethylidene diphosphonic acid, dodecyl trimethyl ammonium chloride and triisopropanolamine in the modifier is 3-3.5:1-1.4:1-1.2.

[0034] The preferably modifier can further increase the specific surface area of the tailing fine powder, improve the activity of the tailing fine powder and reduce the water demand ratio.

[0035] It should be further noted that the addition methods of the modifier and triethanolamine are: mixing the modifier and triethanolamine and then atomizing, and spraying through the feed port of the grinder.

[0036] Preferably, in step e, the addition amount of the modifier is 0.015%-0.018% of the dried product.

[0037] The present invention also provides a tailings fine powder, which is prepared by the preparation method of the tailings fine powder described above.

[0038] The production process of the tailings fine powder provided by the present invention is simple, the material production cost and energy consumption are low, the economic benefit is obvious, and the environmental pollution can also be reduced. Since a large amount of waste is utilized and the consumption of cement and lime is saved, it is a new type of green building material with great promise. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a flowchart for the preparation of the tailings fine powder provided in Embodiment 1 of the present invention;

[0040] Figure 2 It is a schematic structural diagram for the use of the preparation of the tailings fine powder provided in Embodiment 1 of the present invention;

[0041] In the figure, 1 is the first ball mill, 2 is the first magnetic separator, 3 is the second ball mill, 4 is the second magnetic separator, 5 is the vibrating screen, 6 is the dosing system, 7 is the flotation machine, 8 is the thickener, 9 is the dryer, 10 is the grinding aid atomizer, 11 is the ball mill, 12 is the powder separator, 13 is the pipeline, 14 is the second selected ore bin, and 15 is the tailings fine powder bin. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and the drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0043] A preparation method of a tailings fine powder provided by the present invention is carried out by using the following device. Please refer to Figure 2 : The device uses a first ball mill 1 and a first magnetic separator 2 connected in sequence by a pipeline 13; the first magnetic separator 2 has a primary discharge port and a secondary discharge port. The primary discharge port is connected to the vibrating screen 5, and the secondary discharge port is connected to the second ball mill 3; the second ball mill 3 and the second magnetic separator 4 are connected by a pipeline 13; the second magnetic separator 4 has a primary discharge port and a secondary discharge port. The primary discharge port is connected to the vibrating screen 5, and the secondary discharge port is connected to the second selected ore bin 14; the discharge port of the vibrating screen 5 is connected to the flotation machine 7; the medicine inlet in the flotation machine 7 is connected to the dosing system 6, and the discharge port is connected to the thickener 8; the discharge port of the thickener 8 is connected to the dryer 9; the ball mill 11 has a primary feed port and a secondary feed port. The primary feed port is connected to the dryer 9, and the secondary feed has a connection to the grinding aid atomizer 10; the discharge port of the ball mill 11 is connected to the powder separator 12, and the powder separator 12 is connected to the tailings fine powder bin 15.

[0044] Embodiment 1

[0045] This embodiment provides a method for preparing tailings fine powder, which includes the following steps:

[0046] Wet-grind low-grade vanadium-titanium magnetite in the first ball mill 1 to obtain primary pulp. Under a magnetic separation intensity of 4000 Gs, transfer the primary pulp to the first magnetic separator 2 through pipeline 13, and conduct the first magnetic separation on the primary pulp in the first magnetic separator 2 to obtain first selected ore and first magnetic separation tailing pulp; wherein, the mass content of magnetic iron in the low-grade vanadium-titanium magnetite is <20%, the mass content of silicon dioxide is 50%, and the mass content of aluminum oxide is 10%; the grinding fineness of the primary pulp ≥200 mesh accounts for 25%, and the pulp concentration is 80%;

[0047] Wet-grind the first selected ore in the second ball mill 3 to obtain secondary pulp. Under a magnetic separation intensity of 3000 Gs, conduct the second magnetic separation on the secondary pulp in the second magnetic separator 4, store the second selected ore in the second selected ore bin 14, and the remaining is the second magnetic separation tailing pulp. Use a vibrating screen 5 to screen out particles <200 mesh in the first magnetic separation tailing pulp and the second magnetic separation tailing pulp to obtain treated pulp; wherein, the grinding fineness of the secondary pulp ≥200 mesh accounts for 60%, and the pulp concentration is 70%;

[0048] Add flotation reagents to the treated pulp in the dosing system 6, and conduct flotation using a flotation machine 7 to obtain floated pulp; wherein, the flotation reagent is a mixture of oleic acid and poly-succinamide with a mass ratio of 5:1, the addition amount of the flotation reagent is 1‰ of the treated pulp, and the molecular weight of poly-succinamide is 5000;

[0049] Pass the floated pulp into a thickener 8, add a flocculant to the floated pulp for flocculation, stir evenly and then enter a sedimentation tank, let it stand and stratify to obtain upper clear water and lower slurry precipitate with a water content of 30%. Dry the lower slurry precipitate with a water content of 30% in a dryer 9 until the water content <3% to obtain a dried product; wherein, the addition amount of the flocculant is 2‰ of the floated pulp;

[0050] Use a grinding aid atomizer 10 to add grinding aids and modifiers to the dried product, conduct double closed-circuit internal circulation grinding using a ball mill 11, and use a separator 12 to select particles with a Blaine specific surface area >450 m 2 / kg to the tailings fine powder bin 15 to obtain the tailings fine powder; wherein, the grinding aid is a mixture of desulfurized gypsum, triethanolamine, and calcium oxide powder with a mass ratio of 5:0.01:5, the addition amount of the grinding aid is 9% of the dried product, the sulfur content in the desulfurized gypsum is 35%, and the modifier is a mixture of hydroxyethylidene diphosphonic acid, dodecyl trimethyl ammonium chloride, and triisopropanolamine with a mass ratio of 3:1:1, and the addition amount of the modifier is 0.015% of the dried product.

[0051] Example 2

[0052] This example provides a method for preparing tailings fine powder, which includes the following steps:

[0053] The low-grade vanadium-titanium magnetite is wet-ground in the first ball mill 1 to obtain a primary pulp. Under a magnetic separation intensity of 5000 Gs, the primary pulp is transferred to the first magnetic separator 2 through the pipeline 13, and the primary pulp is subjected to the first magnetic separation in the first magnetic separator 2 to obtain the first selected ore and the first magnetic separation tailing pulp; wherein, the mass content of magnetic iron in the low-grade vanadium-titanium magnetite < 20%, the mass content of silicon dioxide is 30%, and the mass content of aluminum oxide is 20%; the grinding fineness of the primary pulp ≥ 200 mesh accounts for 40%, and the pulp concentration is 70%;

[0054] The first selected ore is wet-ground in the second ball mill 3 to obtain a secondary pulp; under a magnetic separation intensity of 1800 Gs, the secondary pulp is subjected to the second magnetic separation in the second magnetic separator 4, the second selected ore is stored in the second selected ore bin 14, and the remaining second magnetic separation tailing pulp is obtained. The < 200-mesh particles in the first magnetic separation tailing pulp and the first magnetic separation tailing pulp are screened out by the vibrating screen 5 to obtain a treated pulp; wherein, the grinding fineness of the secondary pulp ≥ 200 mesh accounts for 80%, and the pulp concentration is 75%;

[0055] Flotation reagents are added to the treated pulp in the dosing system 6, and flotation is carried out using the flotation machine 7 to obtain a flotation pulp; wherein, the flotation reagents are a mixture of oleic acid and polysuccinimide with a mass ratio of 6:1, the addition amount of the flotation reagents is 2‰ of the flotation pulp, and the molecular weight of polysuccinimide is 20000;

[0056] The flotation pulp is fed into the thickener 8, a flocculant is added to the flotation pulp, and after stirring evenly, it enters the sedimentation tank and stands for stratification to obtain upper clear water and lower slurry sediment with a water content of 60%. The lower slurry sediment with a water content of 60% is dried in the dryer 9 to a moisture content < 3% to obtain a dried product; wherein, the addition amount of the flocculant is 3‰ of the flotation pulp;

[0057] The grinding aid atomizer 10 is used to add the grinding aid and the modifier to the dried product, the ball mill 11 is used for double closed-loop internal circulation grinding, and the classifier 12 is used to select particles with a Blaine specific surface area > 450 m 2From / kg to the tailings fine powder bin 15 to obtain the tailings fine powder 15; wherein, the grinding aid is a mixture of desulfurized gypsum, triethanolamine and calcium oxide powder with a mass ratio of 5.2:0.03:5.2, the addition amount of the grinding aid is 11% of the dried material, the sulfur content in the desulfurized gypsum is 50%, and the modifier is a mixture of hydroxyethylidene diphosphonic acid, dodecyl trimethyl ammonium chloride and triisopropanolamine with a mass ratio of 3.5:1.4:1.2, and the addition amount of the modifier is 0.018% of the dried material.

[0058] Example 3

[0059] This example provides a method for preparing tailings fine powder, including the following steps:

[0060] Wet grind the low-grade vanadium-titanium magnetite in the first ball mill 1 to obtain a primary pulp. Under a magnetic separation intensity of 4200 Gs, transfer the primary pulp to the first magnetic separator 2 through the pipeline 13, and perform the first magnetic separation on the primary pulp in the first magnetic separator 2 to obtain the first selected ore and the first magnetic separation tailings pulp; wherein, the mass content of magnetic iron in the low-grade vanadium-titanium magnetite is <20%, the mass content of silicon dioxide is 35%, and the mass content of aluminum oxide is 16%; the grinding fineness of the primary pulp ≥200 mesh accounts for 28%, and the pulp concentration is 73%.

[0061] Wet grind the first selected ore in the second ball mill 3 to obtain a secondary pulp. Under a magnetic separation intensity of 2500 Gs, perform the second magnetic separation on the secondary pulp in the second magnetic separator 4, store the second selected ore in the second selected ore bin 14, and the remaining is the second magnetic separation tailings pulp. Use the vibrating screen 5 to screen out the particles <200 mesh in the first magnetic separation tailings pulp and the first magnetic separation tailings pulp to obtain the treated pulp; wherein, the grinding fineness of the secondary pulp ≥200 mesh accounts for 70%, and the pulp concentration is 73%.

[0062] Add flotation reagents to the treated pulp in the dosing system 6, and perform flotation using the flotation machine 7 to obtain the flotation pulp; wherein, the flotation reagent is a mixture of oleic acid and poly(succinamide) with a mass ratio of 5.5:1, the addition amount of the flotation reagent is 1.5‰ of the flotation pulp, and the molecular weight of poly(succinamide) is 15000.

[0063] Pass the flotation pulp into the thickener 8, add a flocculant to the flotation pulp for flocculation, stir evenly and then enter the sedimentation tank, stand for layering to obtain the upper clear water and the lower slurry sediment with a water content of 45%. Treat the lower slurry sediment with a water content of 45% in the dryer 9 until the moisture content <3% to obtain the dried material; wherein, the addition amount of the flocculant is 2.5‰ of the flotation pulp.

[0064] The grinding aid and modifier are added to the dried material by means of the grinding aid atomizer 10, and double-closed-loop internal circulation grinding is carried out using the ball mill 11. The Blaine specific surface area of the selected particles is > 450 m 2 / kg to the tailings micro-powder bin 15 to obtain the tailings micro-powder 15. Among them, the grinding aid is a mixture of desulfurized gypsum, triethanolamine and calcium oxide powder with a mass ratio of 5.1:0.02:5.1. The addition amount of the grinding aid is 10% of the dried material. The sulfur content in the desulfurized gypsum is 37%. The modifier is a mixture of hydroxyethylidene diphosphonic acid, dodecyl trimethyl ammonium chloride and triisopropanolamine with a mass ratio of 3.2:1.2:1.1. The addition amount of the modifier is 0.016% of the dried material.

[0065] Comparative Example 1

[0066] This comparative example provides a method for preparing tailings micro-powder. The preparation method is exactly the same as that of Example 1, except that oleic acid in Example 1 is replaced with an equal amount of pine oil;

[0067] Other raw materials are the same as those in Example 1.

[0068] Comparative Example 2

[0069] This comparative example provides a method for preparing tailings micro-powder. The preparation method is exactly the same as that of Example 1, except that triethanolamine in Example 1 is replaced with an equal amount of ethylene glycol;

[0070] Other raw materials are the same as those in Example 1.

[0071] Comparative Example 3

[0072] This comparative example provides a method for preparing tailings micro-powder. The preparation method is exactly the same as that of Example 1, except that hydroxyethylidene diphosphonic acid in Example 1 is replaced with an equal amount of sodium tripolyphosphate;

[0073] Other raw materials are the same as those in Example 1.

[0074] Application Example

[0075] The specific surface area, water demand ratio, methylene blue value and 7d, 28d activity index of the tailings micro-powder prepared in the above Examples 1-3 and Comparative Examples 1-3 are detected according to the methods of GB / T 8074 and T / CECS10103. The specific detection results are shown in Table 1.

[0076] Table 1 Detection Results

[0077]

[0078] It can be seen from Table 1 that for the tailings micro-powder prepared in Examples 1-3, its specific surface area can reach 450 m2 per kg, the methylene blue value is between 2.8 and 3.8, and both the 7-day activity index and the 28-day activity index can reach over 70%. The tailings micro-powder provided by the present invention has high activity and low water demand ratio. Its production process is simple, the material production cost and energy consumption are low, the economic benefit is obvious, and it can also reduce environmental pollution. Due to the large amount of waste utilization and the saving of cement and lime usage, it is a promising new type of green building material.

[0079] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, or improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing tailings fine powder, characterized in that, It includes the following steps: Step a: Wet-grind the low-grade vanadium-titanium magnetite to obtain a primary pulp; conduct the first magnetic separation on the primary pulp to obtain a first concentrated ore and a first magnetic separation tailing pulp; Among them, the proportion of particles with a fineness of ≥200 meshes in the primary pulp is 25%-40%, and the pulp concentration is 70%-75%; Step b: Wet-grind the first concentrated ore to obtain a secondary pulp; conduct the second magnetic separation on the secondary pulp to obtain a second concentrated ore and a second magnetic separation tailing pulp, screen and remove particles with a size of <200 meshes in the first magnetic separation tailing pulp and the second magnetic separation tailing pulp to obtain a treated pulp; Among them, the grinding fineness of the secondary pulp with a fineness of ≥200 meshes accounts for 60%-80%, and the pulp concentration is 70%-75%; Step c: Add a flotation reagent to the treated pulp for flotation to obtain a flotation pulp; Among them, the flotation reagent is a mixture of oleic acid and poly(succinamide); Step d: Add a flocculant to the flotation pulp for flocculation precipitation, stand for separation to obtain upper-layer clear water and lower-layer mud precipitate; dry the lower-layer mud precipitate to a moisture content of <3% to obtain a dried product; Step e, adding a grinding aid and a modifier to the dried material, and performing double-closed-circuit internal circulation grinding until the Blaine specific surface area of the particles > 450 m 2 / kg to obtain the tailings fine powder; Among them, the grinding aid is a mixture of desulfurized gypsum, triethanolamine, and calcium oxide powder; the modifier is a mixture of hydroxyethylidene diphosphonic acid, dodecyltrimethylammonium chloride, and triisopropanolamine.

2. The method for preparing tailings fine powder according to claim 1, characterized in that, In step a, the mass content of magnetic iron in the low-grade vanadium-titanium magnetite is <20%, the mass content of silicon dioxide is 30%-50%, and the mass content of aluminum oxide is 10%-20%; and / or In step a, the magnetic separation intensity of the first magnetic separation is 4000 Gs - 4500 Gs; and / or In step b, the magnetic separation intensity of the second magnetic separation is 2800 Gs - 3200 Gs.

3. The method for preparing tailings fine powder according to claim 1, characterized in that, In step c, the mass ratio of oleic acid to poly(succinamide) in the flotation reagent is 5 - 6:

1.

4. The method for preparing tailings fine powder according to claim 3, characterized in that, The molecular weight of the poly(succinamide) is 5000 - 20000.

5. The method for preparing tailings fine powder according to claim 1 or 3, characterized in that, In step c, the addition amount of the flotation reagent is 1‰ - 2‰ of the mass of the treated pulp.

6. The method for preparing tailings fine powder according to claim 1, characterized in that, In step e, the mass ratio of desulfurized gypsum, triethanolamine, and calcium oxide powder in the grinding aid is 5 - 5.2:0.01 - 0.03:5 - 5.2; and / or In step e, the addition amount of the grinding aid is 9% - 11% of the mass of the dried product; and / or In step d, the addition amount of the flocculant is 2‰ - 3‰ of the mass of the flotation pulp.

7. The method for preparing tailings fine powder according to claim 6, characterized in that, The sulfur content in the desulfurized gypsum is 35% - 50%.

8. The method for preparing tailings fine powder according to claim 1, characterized in that, In step e, the mass ratio of hydroxyethylidene diphosphonic acid, dodecyltrimethylammonium chloride, and triisopropanolamine in the modifier is 3 - 3.5:1 - 1.4:1 - 1.

2.

9. The method for preparing tailings fine powder according to claim 1 or 8, characterized in that, In step e, the addition amount of the modifier is 0.015% - 0.018% of the mass of the dried product.

10. A tailings fine powder, characterized in that, Prepared by the method for preparing tailing fine powder according to any one of claims 1 - 9.

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