CN112474065A

CN112474065A - Method for selecting phosphorus from low-grade vanadium titano-magnetite tailings

Info

Publication number: CN112474065A
Application number: CN202011230321.2A
Authority: CN
Inventors: 魏茜; 焦芬; 覃文庆; 杨聪仁; 刘维; 韩俊伟; 董留洋
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2020-11-06
Filing date: 2020-11-06
Publication date: 2021-03-12
Anticipated expiration: 2040-11-06
Also published as: CN112474065B

Abstract

The invention discloses a method for selecting phosphorus from low-grade vanadium titano-magnetite tailings, which comprises the following steps: carrying out low-intensity magnetic separation and tailing discarding on the low-grade vanadium-titanium magnetite tailings to obtain magnetic minerals and phosphorus flotation feed ores; the phosphorus flotation feeding is carried out the size mixing to obtain the ore pulp, and the regulator sodium carbonate and the gangue inhibitor HQ-P are added into the ore pulp in sequence₁HQ-P as collector₂And performing direct flotation phosphorus separation to obtain high-quality phosphate concentrate and phosphate separation tailings. The invention aims at the phosphorus separation of low-grade vanadium titano-magnetite tailings, and adopts low-intensity magnetic separation tailing discarding-magnetic separation tailings positive flotation in view of low phosphorus content of raw oresCompared with the full-flotation phosphorus separation process, the magnetic separation-flotation process has the advantages that the cost is reduced by 20-25% compared with the full-flotation process, and the economic benefit is improved. HQ-P inhibitor of the invention₁With collector HQ-P₂The combined use effectively avoids the problems of serious influence of argillized gangue, difficult fine particle floatation, poor selectivity of the fatty acid collecting agent, low recovery rate under low temperature and the like in phosphorite floatation, and obtains a high-phosphorus-grade phosphate concentrate product under the condition of low medicament dosage.

Description

Method for selecting phosphorus from low-grade vanadium titano-magnetite tailings

Technical Field

The invention belongs to the technical field of mineral processing, and particularly relates to a method for selecting phosphorus from low-grade vanadium titano-magnetite tailings.

Background

The vanadium titano-magnetite is an important ferrous metal mineral resource in China, the storage capacity of the vanadium titano-magnetite in Chengdu area of Hebei exceeds 100 hundred million tons, the vanadium titano-magnetite is another large vanadium titano-magnetite except Panzhihua in China, and the titanium storage capacity is the second nationwide. The resource mineral has complex composition and many associated elements, and contains valuable elements such as phosphorus and the like besides iron. Magnetite is mostly recovered by adopting a magnetic separation process in a phosphosiderite separation plant, and low-grade phosphosiderite tailings have no mature flotation process and medicament system and can only be discarded as waste ores, so that the severe waste of phosphorus resources is caused. Therefore, in the face of the current situation that phosphorite resources are increasingly scarce, research on phosphorus separation of low-grade vanadium titano-magnetite tailings is carried out, and the method has important significance in the aspects of improving the comprehensive utilization rate of resources, reducing the transportation pressure of north China's phosphorus transportation, realizing sustainable development of phosphate fertilizer industry and agriculture in China and the like.

Flotation has always been considered the most efficient method for recovering phosphate rock. The flotation separation is difficult due to the fact that the main phosphorite apatite has extremely similar surface properties to carbonate gangue minerals (dolomite and calcite). In addition, because apatite and dolomite/calcite are mostly complex in embedding relationship, the embedding granularity is fine, the apatite and the dolomite/calcite belong to easily ground minerals, and the apatite and the dolomite/calcite are easily crushed in the crushing and grinding processes to cause serious argillization. The flotation after desliming causes large phosphorus loss, and the flotation concentrate grade and recovery rate are low. The water glass and the fatty acid collecting agent become the most commonly used inhibitor and collecting agent in the phosphorite flotation practice due to the advantages of wide sources, relatively low price and the like. However, the water glass is used as an inhibitor, and the inhibition force on the gangue is insufficient, the dosage of the required medicament is large, so that the gangue floats upwards and is seriously entrained, and the tailing wastewater is difficult to settle; in addition, the fatty acid medicament mainly containing oleic acid (sodium) is used as the collector, particularly in northern areas, the temperature is reduced, the dissolving and dispersing capacity of the fatty acid collector is obviously reduced, the medicament dosage is increased, the phosphorus recovery rate is reduced, and the waste of mineral resources is caused.

Therefore, how to obtain a high-grade phosphate concentrate product and ensure a high flotation recovery rate, a targeted gangue inhibitor and collector for low-grade phosphate ore separation are urgently needed to be developed.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a method for efficiently floating and recovering phosphorus in low-grade vanadium titano-magnetite tailings, which can obtain a high-grade phosphorus concentrate product under the condition of not desliming and simultaneously ensure higher phosphorus flotation recovery rate.

The invention provides a phosphorus separation method of low-grade vanadium titano-magnetite tailings, which comprises the following steps:

1) magnetic separation: firstly, carrying out low-intensity magnetic separation and tailing discarding on low-grade vanadium-titanium magnetite tailings to obtain magnetic minerals and non-magnetic minerals (phosphorus flotation feeding);

2) flotation: mixing the nonmagnetic minerals obtained in the step 1) to obtain ore pulp, and sequentially adding a regulator sodium carbonate and a gangue inhibitor HQ-P into the ore pulp₁HQ-P as collector₂Performing direct flotation phosphorus separation to obtain high-quality phosphate concentrate and phosphate separation tailings;

wherein: HQ-P₁Comprises 100 (10-15) parts by mass of 20-45 parts by mass of water glass and carboxymethylCellulose (CMC) and 2-carboxyphosphorylacetic acid (HPAA);

HQ-P₂the anti-corrosion agent is composed of sodium oleate and polyethylene glycol monomethyl ether (MPEG-200) in a mass ratio of (80-95) to (5-20).

In the step 1), the magnetic field intensity of the low-intensity magnetic separation is 0.2-0.5T.

In the step 2), the modulus of the water glass is 2.5-3.0; the molecular formula of the 2-carboxyl phosphoryl acetic acid (HPAA) is C₂H₅O₆P, the structural formula is as follows:

the molecular formula of the polyethanol monomethyl ether MPEG-200 is C₂₃H₄₈O₁₂The structural formula is as follows:

preferably, the gangue inhibitor HQ-P₁Respectively consists of water glass, carboxymethyl cellulose (CMC) and 2-carboxyl phosphoryl acetic acid (HPAA) with the mass ratio of 100:12: 36.

Preferably, the gangue inhibitor HQ-P₁Respectively consists of water glass, carboxymethyl cellulose (CMC) and 2-carboxyl phosphoryl acetic acid (HPAA) with the mass ratio of 100:13: 39.

Preferably, the collector HQ-P₂Respectively consists of sodium oleate and polyethanol monomethyl ether (MPEG-200) with the mass ratio of 90: 10.

Preferably, the collector HQ-P₂Respectively consists of sodium oleate and polyethanol monomethyl ether (MPEG-200) with the mass ratio of 92: 8.

The direct flotation phosphorus separation operation is one coarse, one sweep and three fine.

The specific steps of the primary roughing operation are as follows: mixing the phosphorus flotation feed ore, adding 800-4000 g/t of sodium carbonate into the ore pulp, and stirring for 2-3 min; adding 200-600 g/t of gangue inhibitor HQ-P₁Stirring 2-3 min; adding 100-500 g/t of collecting agent HQ-P₂Stirring for 2-3 min; and (4) scraping and soaking for 4-6 min to obtain rough concentrate, wherein the product in the tank is scavenging feed ore.

The one-time scavenging operation comprises the following specific steps: adding 30-200 g/t of collecting agent HQ-P into scavenging feed ores₂Stirring for 2-3 min, and scraping for 2-3 min to obtain scavenged foam product, returning the scavenged foam product to the roughing tank, wherein the product in the tank is the tailing product.

The third selection operation comprises the following specific steps: the first concentration, the second concentration and the third concentration are blank concentration, foam scraping is started after full stirring, the foam scraping time is 2-3 min, 1.5-2.5 min and 1.0-2 min respectively, and all middlings are returned to the previous flotation operation in sequence; and obtaining the final phosphate concentrate product.

The term "g/t" used in the present invention refers to the addition amount of the chemical agent relative to the phosphorus ore dressing, for example, the addition amount of the gangue depressant is 200g/t, which means that 200g of the gangue depressant is required to be added for treating 1 ton of phosphorus ore dressing.

The principle of the invention is as follows:

the water glass is an effective inhibitor of silicate gangue minerals and is also a good dispersant, so that the viscosity of the ore pulp is effectively reduced, and the entrainment of fine-grain gangue and mica minerals is reduced. Carboxymethyl cellulose (CMC) is an effective inhibitor and slime flocculant for calcium-containing, magnesium silicate, carbonate gangue minerals, argillaceous minerals, etc. The electrostatic attraction and chemical adsorption between the carboxyl in CMC molecule and calcium ion on the surface of the mollite/dolomite are the main reasons for selective adsorption of CMC on the surface of calcite/dolomite. Many other hydroxyl groups associate with water through hydrogen bonds, resulting in hydrophilic mineral surfaces. In addition, CMC can flocculate fine-grained calcite/dolomite, increasing the probability of action of calcite/dolomite with 2-carboxyphosphorylacetic acid (HPAA). HPAA has 1 phosphorus oxygen group (-PO) in its molecule₃H₂) And 2 carboxylic acid groups (-COOH), in the alkaline ore pulp, HPAA shows stronger anionic property and hydrophilicity due to ionization, and negatively charged oxygen ions are easy to generate electrostatic interaction with calcium ions on the surface of the calcium-containing mineral. Research shows that phosphorus oxy and carboxyl in HPAA molecules are negatively charged, the distance between the two functional groups is close to the Ca-Ca distance on the surface of calcite/dolomite, and the distance is far away from the Ca-Ca distanceSmaller than the Ca-Ca spacing of the apatite surface. Thus, HPAA adsorbs more readily on the calcite/dolomite surface than apatite, further inhibiting the adsorption of the collector, which is inhibited. In contrast, HPAA adsorbs poorly on apatite surfaces and does not affect apatite flotation. The combination of the three inhibitors can more strongly inhibit calcite/dolomite under the condition of reducing the viscosity of ore pulp, particularly selectively inhibit fine-fraction calcite/dolomite, and overcome the defects of large dosage, poor inhibition effect on fine-fraction gangue and the like of the traditional inhibitor. The combined inhibitor has weak action with the surface of the apatite, and basically does not influence the flotation of the apatite.

The polyethanol monomethyl ether (MPEG-200) is a high-surface-activity green environment-friendly nonionic surfactant, and has no collecting property on apatite. After the sodium oleate and the polyethanol monomethyl ether are compounded, the surface activity of a compounded system is higher than that of a single sodium oleate system, and the critical micelle concentration is lower than that of the single polyethanol monomethyl ether and the single sodium oleate. Therefore, the collecting performance of the sodium oleate on the apatite is obviously improved under the low-temperature condition. Sodium oleate and polyethanol monomethyl ether are subjected to co-adsorption on the surface of apatite, due to the interaction of hydrophobic chains and the reduction of electrostatic repulsion among ionic groups, the adsorption effect of the sodium oleate is enhanced by the existence of MPEG-200, and particularly under the condition of low concentration, the adsorption of the compound collector on the surface of the apatite is stronger than that of single sodium oleate. Compared with the single sodium oleate serving as the collecting agent, the composite collecting agent has denser flotation foam, large foam ore carrying capacity and strong collecting performance on fine-grained apatite, and is more favorable for improving the flotation recovery rate of the apatite.

The combined inhibitor can effectively and selectively inhibit dolomite/calcite, reduce mechanical entrainment of fine-grain gangue and mica minerals, is matched with a compounded collecting agent for use, and can simultaneously ensure the phosphorus grade and the phosphorus recovery rate in phosphate concentrate under the low-temperature condition.

The invention has the beneficial effects that:

(1) aiming at the phosphorus separation of the low-grade vanadium-titanium magnetite tailings, in view of low phosphorus content of raw ores, the process of low-intensity magnetic separation tailing discarding in advance and magnetic separation tailing direct flotation phosphorus separation is adopted, and compared with full flotation phosphorus separation, the magnetic separation-flotation process has the advantages that the cost is reduced by 20-25% compared with the full flotation process, and the economic benefit is improved;

(2) based on the principle of mixed application, HQ-P inhibitor with good effect of inhibiting calcium-containing gangue such as calcite/dolomite₁The phosphorus-containing water glass is combined with water glass according to a certain weight proportion, so that argillaceous gangue can be effectively inhibited, and a high-grade phosphate concentrate product is obtained;

(3) by compounding sodium oleate and polyethanol monomethyl ether, the apatite collecting agent has stronger apatite collecting capability under the conditions of low temperature and low dosage. The purpose of selective separation can be achieved under the condition of no mud removal through the matching use of the combined inhibitor and the compound collector. The raw materials of the medicament have wide sources, are easy to prepare and easy to implement industrial operation;

(4) after the phosphorus separation method and the reagent system provided by the invention are adopted, when the low-grade phosphorus-containing vanadium titano-magnetite tailings are treated, the tailings contain 0.8-2.5% of phosphorus, the phosphorus grade in the phosphorus concentrate is more than 35%, and the phosphorus flotation operation recovery rate is more than 77%.

Drawings

FIG. 1 is a flow chart of a sorting process of example 1 and comparative examples 1 to 5;

FIG. 2 is a flow chart of a sorting process of comparative example 6;

FIG. 3 is a flow chart of the sorting process of example 2 and comparative example 7;

Detailed Description

Example 1

The mineral dressing tailings of a certain vanadium titano-magnetite in Hebei river have low phosphorus content and P content₂O₅The content of the mineral is 1.63%, the relative content of the apatite is about 6%, the main gangue minerals are calcite and dolomite, the relative content of the minerals is up to 12.5%, and the mineral also contains gangue such as mica, quartz and the like. The argillization is serious, the content of minus 38 mu m reaches 40 percent, the particle size distribution range of apatite and calcite/dolomite is 10 to 150 mu m, the thickness distribution is not uniform, and the apatite separation index is not ideal.

The process flow of this example is shown in fig. 1, and the specific sorting process and the pharmaceutical system are as follows:

(1) firstly, carrying out low-intensity magnetic separation and tailing discarding on the tailings, wherein the magnetic field intensity is 0.4T, and obtaining nonmagnetic minerals (phosphorus flotation feeding);

(2) roughing operation: mixing the phosphorus flotation feed ore, and stirring for 1 min; sequentially adding 1250g/t of sodium carbonate, stirring for 2min, adding 300g/t of gangue inhibitor HQ-P₁Stirring for 2min, and adding 400g/t of collecting agent HQ-P₂Stirring for 2min, and scraping and soaking for 5min to obtain rougher concentrate and scavenging feed;

(3) primary scavenging operation: adding 90g/t of collecting agent HQ-P into scavenging feed ore₂Stirring for 2min, and scraping and soaking for 3min to obtain final tailings;

(4) and (3) performing tertiary concentrate operation: and (3) blank concentration is carried out on the first concentration, the second concentration and the third concentration, and the foam scraping time is respectively 2min, 2min and 1.5min, so that the final phosphate concentrate is obtained.

The gangue inhibitor HQ-P₁Respectively consists of water glass, carboxymethyl cellulose (CMC) and 2-carboxyl phosphoryl acetic acid (HPAA) with the mass ratio of 100:12: 36.

The collector HQ-P₂Consists of sodium oleate and polyethanol monomethyl ether (MPEG-200) with the mass ratio of 90: 10.

Wherein sodium carbonate is prepared into 5% water solution, and added with gangue inhibitor HQ-P₁Preparing into 2% aqueous solution, adding collecting agent HQ-P₂Prepared into 2 percent aqueous solution for adding. The test results are shown in table 1# 1.

Comparative example 1

The process flow was the same as in example 1 except that a single water glass was used as the gangue depressant. The flotation results are shown in figure 2 #.

Roughing: 300g/t water glass, 400g/t HQ-P₂；

Sweeping: 90g/t HQ-P₂；

Comparative example 2

The process flow was the same as in example 1 except that the collector was sodium oleate alone. The flotation results are shown in # 3 in table 1.

Roughing: 300g/t HQ-P₁400g/t sodium oleate;

sweeping: 90g/t sodium oleate;

comparative example 3

The process flow was the same as in example 1 except that the gangue depressants used were single water glass and the collector used was single sodium oleate. The flotation results are shown in # 4 in table 1.

Roughing: 300g/t of water glass and 400g/t of sodium oleate

Sweeping: 90g/t of sodium oleate

Comparative example 4

The process flow is the same as in example 1, except that the gangue inhibitor HQ-P₁Respectively consists of water glass, carboxymethyl cellulose (CMC) and 2-carboxyl phosphoryl acetic acid (HPAA) with the mass ratio of 100:25: 30. The test results are shown in table 1 as # 5.

Roughing: 300g/t HQ-P₁HQ-P of 400g/t₂；

Sweeping: 90g/t HQ-P₂；

Comparative example 5

The process flow is identical to that of example 1, except that the collector HQ-P₂The test result is shown in 6# in Table 1, which is composed of sodium oleate and polyethanol monomethyl ether (MPEG-200) with a mass ratio of 100: 20.

Roughing: 300g/t HQ-P₁HQ-P of 400g/t₂；

Sweeping: 90g/t HQ-P₂；

Comparative example 6

The phosphorus-selecting feed ore is completely screened out by materials with a granularity of-400 meshes (-0.038mm), then the flotation test is carried out, the test flow is shown in figure 2, and the test result is shown in 7# in table 1. Wherein the gangue inhibitor adopts single water glass, and the collecting agent adopts single sodium oleate.

Roughing: 300g/t of water glass and 400g/t of sodium oleate

Sweeping: 90g/t of sodium oleate

TABLE 1 TEST 1# -7 # FULL FLOW CLOSED CIRCUIT COMPARATIVE TEST RESULTS/% (amended)

As can be seen from Table 1, the amount of gangue depressants and collectors was compared with that of water glass and collector under the same dosage conditionsAgent HQ-P₂Combination (2 # in Table 1), inhibitor HQ-P₁Combined with sodium oleate (No. 3 in Table 1), water glass and sodium oleate (No. 4 in Table 1), HQ-P₁With HQ-P₂The combination (1 # in Table 1) enables higher P₂O₅Grade and P₂O₅And (4) recovering rate. Changing HQ-P₁When the phosphorus phase in the phosphate concentrate is obtained, the phosphorus recovery rate is reduced by 6.53 percent according to the mass ratio of the medium active components (5 # in table 1) and the comparative example 1 (1 # in table 1); changing HQ-P₂When the phosphorus recovery rate in the phosphorus concentrate is comparable to that obtained in comparative example 1 (No. 1 in Table 1), the weight ratio of the medium active components (No. 6 in Table 1), and the phosphorus recovery rate are reduced by 4.13%, which shows that HQ-P used in example 1₁And HQ-P₂The mass ratio of the active components is more suitable for selecting the low-grade vanadium titano-magnetite. In comparative example 6 (7#), the material with minus 0.038mm removed has the effect of improving the grade of the phosphate concentrate compared with comparative example 3(4#), but the phosphate grade of the phosphate concentrate is still lower than 35%, and the phosphorus content in the deslimed mud product is 38.73%, so that the loss is too large, and the problem of low grade of the phosphate concentrate cannot be solved by desliming. HQ-P described above₁And HQ-P₂The combination is an excellent phosphorus flotation medicament.

Example 2

Certain low grade vanadium titano-magnetite tailings, P, of Panzhihua₂O₅At 1.82% mineral content, the mineral composition is relatively complex, the main gangue minerals being quartz, calcite, dolomite and mica, with a relative mineral content of apatite of about 7% and calcite/dolomite of up to 16%. The fineness of the tailings is-74 mu m and accounts for 75%, and apatite and calcite/dolomite belong to fine particle embedded cloth and belong to low-grade refractory phosphorus-containing iron tailings.

The process flow of this example is shown in fig. 2, and the specific sorting process and the pharmaceutical system are as follows:

(1) firstly, carrying out low-intensity magnetic separation and tailing discarding on the tailings, wherein the magnetic field intensity is 0.35T, and obtaining nonmagnetic minerals (phosphorus flotation feeding);

(2) roughing operation: mixing the phosphorus flotation tailings, and stirring for 1 min; sequentially adding 3000g/t sodium carbonate, stirring for 2min, and adding 400g/t gangue inhibitor HQ-P₁Stirring for 2min, and adding 300g/t of collecting agent HQ-P₂Stirring for 2min, and scraping and soaking for 5.5min to obtain roughed concentrate and scavenging feed ore;

(3) primary scavenging operation: adding 100g/t of collecting agent HQ-P into scavenging feed ore₂Stirring for 2min, and scraping and soaking for 2.5min to obtain final tailings;

(4) and (3) performing tertiary concentrate operation: and (3) blank concentration is carried out on the first concentration, the second concentration and the third concentration, and the foam scraping time is respectively 2.5min, 2min and 1.5min, so that the final phosphate concentrate is obtained.

The gangue inhibitor HQ-P₁Respectively consists of water glass, carboxymethyl cellulose (CMC) and 2-carboxyl phosphoryl acetic acid (HPAA) with the mass ratio of 100:13: 39.

The collector HQ-P₂Consists of sodium oleate and polyethanol monomethyl ether (MPEG-200) with the mass ratio of 92: 8.

The collector is prepared into 2.5% aqueous solution, and the gangue inhibitor is added into the aqueous solution with the mass concentration of 5%. The test results are shown in table 2 as # 8.

Comparative example 7

The process flow was the same as in example 2 except that the gangue depressants used were single water glass and the collector used was single sodium oleate. The flotation results are shown in table 2# 9.

Roughing: 400g/t of water glass and 300g/t of sodium oleate

Sweeping: 100g/t of sodium oleate

TABLE 2 results of the 8# to 9# full-run closed-circuit comparative experiments%

As shown in Table 2, HQ-P was used as a collector, compared with the conventional sodium silicate used as an inhibitor and sodium oleate used as a collector (9 # in Table 2)₁And HQ-P₂Combined action (8 # in Table 2), phosphorus concentrate P was obtained₂O₅The content is improved by 7.55 percent, and the phosphorus recovery rate is improved by 9.34 percent. The above results demonstrate HQ-P₁And HQ-P₂The combination is superiorGood phosphorus flotation agent.

Claims

1. A method for selecting phosphorus from low-grade vanadium titano-magnetite tailings comprises the following steps:

1) magnetic separation: firstly, carrying out low-intensity magnetic separation and tailing discarding on low-grade vanadium-titanium magnetite tailings to obtain magnetic minerals and non-magnetic minerals;

wherein: HQ-P₁The high-performance sodium silicate-sodium borate composite material is composed of water glass, carboxymethyl cellulose (CMC) and 2-carboxyl phosphoryl acetic acid (HPAA) in a mass ratio of 100 (10-15) to 20-45;

HQ-P₂consists of 80-95 wt% and 5-20 wt% of sodium oleate and MPEG-200.

2. The method for separating phosphorus from low-grade vanadium titano-magnetite tailings according to claim 1, wherein in the step 1), the magnetic field strength of the low-intensity magnetic separation is 0.2-0.5T; in the step 2), the modulus of the water glass is 2.5-3.0; the molecular formula of the 2-carboxyl phosphoryl acetic acid HPAA is C₂H₅O₆P, the structural formula is as follows:

；

。

3. the method for selecting phosphorus from low-grade vanadium titano-magnetite tailings according to claim 1 or 2, characterized in that the gangue inhibitionAgent HQ-P₁The high-performance sodium carboxymethyl cellulose sodium silicate-sodium carboxymethyl cellulose (CMC) and 2-carboxyphosphoryl acetic acid (HPAA) in a mass ratio of 100:12: 36.

4. The method for selecting phosphorus from low-grade vanadium titano-magnetite tailings according to claim 1 or 2, wherein the gangue inhibitor HQ-P₁The high-performance sodium carboxymethyl cellulose sodium silicate-sodium carboxymethyl cellulose (CMC) and 2-carboxyphosphoryl acetic acid (HPAA) in a mass ratio of 100:13: 39.

5. The method for separating phosphorus from low-grade vanadium titano-magnetite tailings according to claim 1 or 2, wherein the collector HQ-P₂Consists of sodium oleate and polyethanol monomethyl ether MPEG-200 with the mass ratio of 90: 10.

6. The method for separating phosphorus from low-grade vanadium titano-magnetite tailings according to claim 1 or 2, wherein the collector HQ-P₂Consists of sodium oleate and polyethanol monomethyl ether MPEG-200 with the mass ratio of 92: 8.

7. The method for selecting phosphorus from low-grade vanadium titano-magnetite tailings according to claim 1 or 2, wherein the positive flotation phosphorus selection operation is one rough and three fine.

8. The method for selecting phosphorus from low-grade vanadium titano-magnetite tailings according to claim 7, wherein the primary roughing operation comprises the following specific steps: mixing the phosphorus flotation feed ore, adding 800-4000 g/t of sodium carbonate into the ore pulp, and stirring for 2-3 min; adding 200-600 g/t of gangue inhibitor HQ-P₁Stirring for 2-3 min; adding 100-500 g/t of collecting agent HQ-P₂Stirring for 2-3 min; and (4) scraping and soaking for 4-6 min to obtain rough concentrate, wherein the product in the tank is scavenging feed ore.

9. The method for selecting phosphorus from low-grade vanadium titano-magnetite tailings according to claim 7, wherein the specific steps of the primary scavenging operation are as follows: adding 30-200 g/t of collecting agent HQ-P₂Stirring for 2-3 min, and scraping for 2-3 min to obtain scavenged foam product, returning the scavenged foam product to the roughing tank, wherein the product in the tank is the tailing product.

10. The method for selecting phosphorus from low-grade vanadium titano-magnetite tailings according to claim 7, wherein the three selection operations comprise the following specific steps: the first concentration, the second concentration and the third concentration are blank concentration, foam scraping is started after full stirring, the foam scraping time is 2-3 min, 1.5-2.5 min and 1.0-2 min respectively, and all middlings are returned to the previous flotation operation in sequence; and obtaining the final phosphate concentrate product.