Process for recovering apatite through flotation of iron separation tailings

Abstract

The invention discloses a process for recovering apatite from iron ore dressing tailings through flotation, and belongs to the technical field of ore dressing. The method comprises the following steps: 1, carrying out high-gradient magnetic separation treatment on the iron separation tailings, recovering and removing magnetic iron-containing minerals, returning the removed iron-containing minerals to an iron separation main process, feeding the tailings into a chute to remove large-particle gangue minerals, and then feeding the tailings into a thickening pool to be concentrated; secondly, sulfide ore flotation and gypsum flotation are sequentially carried out on the bottom flow products of the thickening pool to remove impurities prone to interference, then apatite collecting and direct flotation are carried out, and apatite concentrate is obtained; and 3, carrying out ultrafine grinding dissociation and impurity selective argillization on the apatite concentrate, and then carrying out apatite closed-loop concentration to obtain a qualified apatite concentrate product. According to the method, the apatite in the iron ore dressing tailings can be well recycled, and the method has great economic feasibility.

Description

Technical Field

[0001] The invention belongs to the technical field of ore dressing, and more specifically, relates to a process for recovering apatite by flotation of iron ore tailings. Background Art

[0002] Phosphate ore is one of the important mineral resources and is widely used in military, people's livelihood, chemical industry, agriculture and other fields. Many existing iron ores are associated with a certain grade of apatite resources, but due to their low grade and complex associated components that are difficult to separate, it is difficult to separate and remove impurities for resource utilization. They will be directly discharged into the tailings pond with the iron tailings, causing serious loss of phosphorus resources and increasing the amount of iron tailings discharged. The volume of phosphorus-containing iron tailings in the natural environment is huge, and the corresponding phosphorus resources are extremely large. The recovery and utilization of phosphorus in phosphorus-containing iron tailings can greatly guarantee the supply of phosphorus resources, and the tailings phosphorus recovery omits the high-energy consumption and high-cost process of front-end crushing and grinding, which has great economic feasibility.

[0003] Low-grade, complex and difficult-to-remove impurities apatite resources have disadvantages such as poor floatability, fine embedded particle size, many similar floatable impurity ores, large gypsum interference, and high concentrate enrichment ratio requirements. The traditional flotation apatite process is difficult to capture, recover and separate the apatite in the tailings, and there are production problems such as poor quality and low recovery. The economic feasibility is weak and it is difficult to adapt to market fluctuations. Summary of the invention

[0004] 1. Problems to be solved

[0005] Aiming at the problem that the traditional flotation apatite process is difficult to achieve the capture, recovery and separation and impurity removal of apatite in iron ore tailings, the present invention provides a flotation apatite recovery process for iron ore tailings, which can achieve better recovery and utilization of apatite in iron ore tailings and has great economic feasibility.

[0006] 2. Technical solution

[0007] To solve the above problems, the present invention adopts the following technical solutions.

[0008] A process for recovering apatite by flotation of iron ore tailings comprises the following steps:

[0009] 1. The tailings are subjected to high-gradient magnetic separation to recover and remove magnetic iron-containing minerals, and the removed iron-containing minerals are returned to the main iron selection process. The tailings enter the chute to remove large-particle gangue minerals, and then enter the thickening tank for concentration;

[0010] 2. The bottom flow products of the thickening tank are successively subjected to sulfide ore flotation and gypsum flotation to remove interfering impurities, and then apatite capture positive flotation is carried out to obtain apatite concentrate;

[0011] 3. The apatite concentrate is subjected to ultrafine grinding for dissociation and impurity selective mudification, and then the apatite is subjected to closed-circuit concentration to obtain a qualified apatite concentrate product.

[0012] As a further improvement of the technical solution, in step one, the pulsation frequency is 100-200r / min, the pulsation stroke is 5-15mm, the magnetic induction intensity is 0.8-1.3T, the slurry concentration is 10%-20%, and the +150 mesh in the fine-grained product of the chute is ≤5%.

[0013] As a further improvement of the technical solution, in step 2, the concentration of sulfide ore flotation is 25%-35%, and copper sulfate, collector and 2# oil frother are added in sequence during the process, with the amount of copper sulfate being 70-130 g / t, the amount of collector being 70-130 g / t, and the amount of 2# oil frother being 15-20 g / t.

[0014] As a further improvement of the technical solution, the collector for flotation of the sulfide ore is at least one of ethyl xanthate, butyl xanthate, black medicine, and thiamine ester.

[0015] As a further improvement of the technical solution, in the step 2, a fatty acid collector MG is added during gypsum flotation, the dosage is 50-100 g / t, and the flotation time is 13-20 min; the fatty acid collector MG is obtained by saponifying 30-50 parts of modified oleic acid, 20-40 parts of long-chain alkanoic acid, 20-40 parts of long-chain olefinic acid, 10-20 parts of linoleic acid and 10-20 parts of isomeric alcohol polyoxyethylene ether.

[0016] As a further improvement of the technical solution, in step 2, a pH adjuster, a combined inhibitor YW and a combined collector 3S are added in sequence during apatite flotation, the pH adjuster needs to control the pH of the slurry to 8-10, the amount of the combined inhibitor is 1.3-1.8 kg / t, and the amount of the combined collector is 500-1000 g / t; the pH adjuster is a carbonate adjuster; the combined collector 3S is composed of 30-50 parts of a fatty acid collector MG, 30-50 parts of heavy alkylbenzene sulfonic acid and 10-20 parts of oxidized paraffin soap; the combined inhibitor YW is composed of 40-70 parts of water glass and 20-40 parts of organic cellulose.

[0017] As a further improvement of the technical solution, in the step three, when the apatite concentrate is subjected to ultrafine grinding and dissociation, the slurry concentration is controlled to be 40-60%, the grinding time is 1-4 minutes, and the grinding fineness is -200 mesh ≥98%.

[0018] As a further improvement of the technical solution, in step three, the flotation column used for closed-circuit concentration of apatite is at least one of an aerated flotation column, a microbubble countercurrent flotation column and a microbubble jet flotation column.

[0019] As a further improvement of the technical solution, in step three, the number of closed-circuit concentration passes of apatite is controlled to be 2-5.

[0020] As a further improvement of the technical solution, the number of the cleaning paths is 3. In cleaning I, 20-50 g / t of combined collector 3S is first added, and then 50-100 g / t of combined inhibitor YW is added. In cleaning II, only 50-100 g / t of combined inhibitor YW is added. In cleaning III, only 20-50 g / t of combined inhibitor YW is added.

[0021] 3. Beneficial effects

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The present invention discloses a process for recovering apatite by flotation of iron tailings, which adopts a combined magnetic-gravity-flotation separation method, and develops a high-gradient magnetic separation process for recovering iron - chute for removing stubborn stone - sulfide ore flotation for removing impurities - easy-floating gypsum for removing impurities - apatite strong capture and flotation - concentrate regrinding and dissociation and selective mudification - apatite reselection for removing impurities, which achieves economic feasibility while ensuring the quality and yield of the concentrate;

[0024] (2) The present invention is a process for recovering apatite by flotation of iron ore tailings. Different novel combined collectors and high-efficiency inhibitors are used for different process stages, which greatly solves the problem of large dosage of traditional reagents and difficulty in separating impurities. The apatite grade P205 of the concentrate product is higher than 30%, and the yield is higher than 52%;

[0025] (3) The present invention provides a process for recovering apatite by flotation from iron ore tailings, which creatively introduces a chute decontamination process, ultrafine grinding dissociation and selective mudification of impurities, and provides a new method for the separation of apatite with properties very close to those of minerals during flotation, greatly improves the quality of the concentrate, and effectively promotes the recovery of apatite from the huge reserves of iron ore tailings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the gypsum foam state diagram for positive flotation;

[0027] Figure 2 The present invention is a flow chart of a process for recovering apatite by flotation of iron ore tailings. DETAILED DESCRIPTION

[0028] Exemplary embodiments of the present invention are described in detail below. Although these exemplary embodiments are described in sufficient detail to enable those skilled in the art to implement the present invention, it should be understood that other embodiments may be implemented and various changes may be made to the present invention without departing from the spirit and scope of the present invention. The more detailed description of the embodiments of the present invention below is not intended to limit the scope of the claimed invention, but is merely for illustration and does not limit the description of the features and characteristics of the present invention, in order to propose the best mode for performing the present invention, and is sufficient to enable those skilled in the art to implement the present invention. Therefore, the scope of the present invention is limited only by the appended claims.

[0029] A process for recovering apatite from iron ore tailings by flotation, such as Figure 2 As shown, the following steps are included:

[0030] 1. The iron ore tailings are subjected to high gradient magnetic separation to recover and remove magnetic iron-containing minerals, and the removed iron-containing minerals are returned to the main iron ore selection process. The tailings enter the chute to remove large-particle gangue minerals, and then enter the thickening tank for concentration.

[0031] Calculated by mass fraction, the phosphorus grade P205 in the original ore meets the requirements of 1.5-4.5%, Mg grade is not higher than 4%, Si grade is 7-15%, Ca grade is 5-14%, S grade is 5-10%, and Fe grade is 3-10%. It mainly contains gangue minerals such as quartz, albite, muscovite, chlorite, and ankerite. The content of dihydrate gypsum in gypsum is ≥80%.

[0032] In this step, the high gradient magnetic separation pulsation frequency is between 100-200r / min, the pulsation stroke is between 5-15mm, the magnetic induction intensity is between 0.8-1.3T, the pulp concentration is between 10%-20%, and the +150 mesh in the fine-grained product of the chute is ≤5%. The grooved spiral chute is used to ensure better results. Compared with other gravity separation equipment such as shaking tables and centrifuges, it occupies a smaller area and has lower energy consumption. It is more economically feasible for phosphorus impurity removal. When separating coarse-grained minerals, +150 mesh still has apatite and gangue embedded, but the content is lower than that of other easily interfering gangue such as iron dolomite. Although it may cause a certain loss of apatite, it reduces the pressure on the back-end impurity removal.

[0033] 2. The bottom flow products of the thickening tank are successively subjected to sulfide ore flotation and gypsum flotation to remove interfering impurities, and then subjected to apatite capture positive flotation to obtain apatite concentrate.

[0034] In this step, the concentration of sulfide ore flotation is between 25% and 35%, and the reagents added successively are copper sulfate, collector and 2# oil frother, the amount of copper sulfate is 70-130g / t, the amount of collector is 70-130g / t, and the amount of 2# oil frother is 15-20g / t. Sulfide ore has a certain interference with the subsequent removal of apatite, so the amount of reagents is used in accordance with the principle of excess use. The collector for sulfide ore flotation is at least one of ethyl xanthate, butyl xanthate, black medicine, and thiamine ester.

[0035] In gypsum flotation, only fatty acid collector MG is added, with a dosage of 50-100g / t. The designed flotation time is between 13-20min. Gypsum mainly exists in the form of dihydrate gypsum, which is very easy to float. Because the foam volume is large and sticky (such as Figure 1 The fatty acid collector MG is obtained by saponifying 30-50 parts of modified oleic acid, 20-40 parts of long carbon chain alkanoic acid, 20-40 parts of long carbon chain olefinic acid, 10-20 parts of linoleic acid and 10-20 parts of isomeric alcohol polyoxyethylene ether.

[0036] The reagents added to apatite flotation are pH adjuster, combined depressant YW and combined collector 3S. The pH adjuster needs to control the pH of the pulp between 8-10. The combined depressant dosage is 1.3-1.8kg / t, and the combined collector dosage is 500-1000g / t. Among them, the pH adjuster is a carbonate adjuster, the combined collector 3S is composed of 30-50 parts of fatty acid collector MG, 30-50 parts of heavy alkylbenzene sulfonic acid and 10-20 parts of oxidized paraffin soap, and the combined depressant YW is composed of 40-70 parts of water glass and 20-40 parts of organic cellulose. The water glass needs to be prepared before use. The combined inhibitor 3S still belongs to fatty acids, and has better flotation effect under alkaline conditions. Because there are many interfering impurities, traditional inhibitors are difficult to inhibit well, and due to poor selectivity, apatite is easily inhibited. Therefore, according to the characteristics of calcium-containing minerals such as iron dolomite and dolomite, which are difficult to separate gangue, a combined inhibitor YW is designed, and a special targeting carrier is introduced into it to achieve targeted inhibition.

[0037] 3. The apatite concentrate is subjected to ultrafine grinding for dissociation and impurity selective mudification, and then the apatite is subjected to closed-circuit concentration to obtain a qualified apatite concentrate product. The final concentrate product has an apatite grade P205 higher than 30% and a yield higher than 52%.

[0038] In this step, the pulp concentration is controlled to be 40-60% when the apatite concentrate is subjected to ultrafine grinding for dissociation, the grinding time is 1-4 minutes, and the grinding fineness is ≥98% at -200 mesh. The ultrafine embedded gangue of apatite is separated by ultrafine grinding, and the flotation of chlorite and muscovite, which are less hard than apatite and easy to be muddy, is reduced by grinding, and the effect of inhibitors on the concentrate is reduced. The agglomeration effect of 3S and the natural floatability of apatite are used to get rid of the disadvantages of fine particle size and the disadvantages of reagents being consumed by impurity ore mud, thereby achieving impurity removal.

[0039] The flotation column used in the closed-circuit concentration of apatite is at least one of an aerated flotation column, a microbubble countercurrent flotation column and a microbubble jet flotation column. The flotation column has the characteristics of improving the grade of the concentrate, and the flotation column has an ultra-long pulp movement distance, which can prolong the number and time of apatite dispersion and agglomeration, and has a positive effect on the removal of impurities in its clusters.

[0040] The number of fine cleaning passes is controlled at 2-5, generally 3. First, add 20-50g / t of combined collector 3S to fine I, then add 50-100g / t of combined inhibitor YW, only add 50-100g / t of combined inhibitor YW to fine II, and only add 20-50g / t of combined inhibitor YW to fine III.

[0041] Aiming at the characteristics of low apatite grade and large impurity interference in iron tailings, the present invention adopts a magnetic-gravity-flotation combined process according to the characteristics of different interfering impurities, and develops a high-gradient magnetic separation iron collection - chute stubborn stone removal - sulfide ore flotation impurity removal - easy-floating gypsum impurity removal - apatite strong collection flotation - concentrate re-grinding dissociation and selective mudification - apatite re-selection impurity removal process, as well as matching high-efficiency selective collectors and super-selective inhibitors.

[0042] First, the magnetic minerals are removed by high gradient magnetic separation and returned to the process grinding step. According to the different hardness of each mineral: apatite hardness 5, quartz hardness 7, albite hardness 6-6.5, muscovite hardness 2.5-3, chlorite hardness 2-3, and iron dolomite hardness 6.5-7, it can be seen that the hardness of apatite is the lowest except for easily muddy minerals, so the amount of apatite in the large-particle ore of iron tailings is small, and the abandonment of large-particle ore has little effect on its yield. Dolomite is the most difficult similar floatable mineral to separate in the back-end apatite impurity removal. With its high hardness and high occurrence in the large-particle ore of tailings, it can be removed to a certain extent by spiral chute gravity separation, which reduces the pressure on the removal of impurities in the back-end apatite concentrate.

[0043] There is no mature specific selective agent for the positive flotation and impurity removal of gypsum in the flotation process of phosphate ore. In addition, gypsum and apatite have similar properties. In the process of floating gypsum, apatite is easily selected together, resulting in a waste of apatite. Therefore, a fatty acid collector MG was developed based on the characteristics of dihydrate gypsum, the main form of gypsum, which is easy to float. By adjusting the dosage of the agent, most of the dihydrate gypsum can be removed by positive flotation with minimal loss of apatite. The remaining anhydrous gypsum is not floatable and will not affect the quality of apatite concentrate. In view of the ultra-low grade, complex and difficult to select apatite in iron tailings, in order to get rid of the characteristics of large dosage of traditional agents, high flotation yield and low recovery rate, a composite high-efficiency phosphorus agent was developed, which greatly reduces the cost of phosphorus collecting agents, makes the resource utilization of phosphorus tailings more economically feasible, and greatly reduces the pressure of impurity removal at the back end.

[0044] The process of the present invention is further described below by means of specific examples.

[0045] Example 1

[0046] Taking a certain iron ore tailing as the research object, the main components of the iron ore tailing are: P2O5 grade is 2.17%, Mg grade is 1.79%, Si grade is 13.11%, Ca grade is 9.81%, S grade is 7.44%, and Fe grade is 7.61%. The following phosphorus selection process is carried out:

[0047] (1) A Slon-2500 pulsating high gradient magnetic separator was used, with a pulsating frequency of 130 r / min, a pulsating stroke of 8 mm, a magnetic induction intensity of 1.0 T, and a pulp concentration of 15%. After magnetic separation, the ore entered a grooved spiral chute to remove large particles, and the fine-grained concentrate entered a thickening tank to be concentrated to a concentration of 33% before entering flotation.

[0048] (2) Reverse flotation to remove impurities: 110 g / t copper sulfate, 110 g / t ethyl xanthate, and 20 g / t 2# oil were added successively for desulfurization treatment, and then 70 g / t MG was added for degypsum treatment.

[0049] (3) Apatite roughing: First, add 1.2 kg / t sodium carbonate to adjust the pH, then add 1.5 kg / t combined depressant YW, and finally add 600 g / t 3S for apatite positive flotation.

[0050] (4) Regrinding and beneficiation of concentrate: The grinding concentration of the concentrate is controlled at 45%. After grinding for 2 minutes with a vertical stirred mill, the concentration is adjusted to 30% for beneficiation. A downstream flotation column is used. First, 35 g / t of combined collector 3S is added to concentrate I, and then 80 g / t of combined inhibitor YW is added. 80 g / t of combined inhibitor YW is added to concentrate II, and only 40 g / t of combined inhibitor YW is added to concentrate III.

[0051] The final P2O5 grade and recovery rate of the phosphate concentrate were 30.64% and 57.63% respectively, and the Mg grade was 0.58%. Qualified apatite concentrate was obtained with a large yield and obvious economic benefits.

[0052] Example 2

[0053] A high-magnesium (ferrodolomite) iron ore tailings was taken as the research object. The main components of the iron ore tailings are: P2O5 grade is 2.77%, Mg grade is 3.42%, Si grade is 12.41%, Ca grade is 10.52%, S grade is 6.84%, and Fe grade is 8.82%. The following phosphorus selection process is carried out:

[0054] (1) A Slon-2500 pulsating high gradient magnetic separator was used, with a pulsating frequency of 130 r / min, a pulsating stroke of 8 mm, a magnetic induction intensity of 1.0 T, and a pulp concentration of 15%. After magnetic separation, the ore entered a grooved spiral chute to remove large particles, and the fine-grained concentrate entered a thickening tank to be concentrated to a concentration of 33% before entering flotation.

[0055] (2) Reverse flotation to remove impurities: 100 g / t copper sulfate, 100 g / t ethyl xanthate, and 20 g / t 2# oil were added successively for desulfurization treatment, and then 80 g / t MG was added for degypsum treatment.

[0056] (3) Apatite roughing: First, add 1.2 kg / t sodium carbonate to adjust the pH, then add 1.5 kg / t combined depressant YW, and finally add 750 g / t 3S for apatite positive flotation.

[0057] (4) Regrinding and beneficiation of concentrate: The grinding concentration of the concentrate is controlled at 45%. After grinding for 2.5 minutes with a vertical stirred mill, the concentration is adjusted to 30% for beneficiation. A downstream flotation column is used. First, 40 g / t of combined collector 3S is added to concentrate I, and then 90 g / t of combined inhibitor YW is added. 90 g / t of combined inhibitor YW is added to concentrate II. Only 40 g / t of combined inhibitor YW is added to concentrate III, and only 20 g / t of combined inhibitor YW is added to concentrate IV.

[0058] The final P2O5 grade and recovery rate of the phosphate concentrate were 30.38% and 50.68% respectively, and the Mg grade was 0.72%. Qualified apatite concentrate was obtained. Although the output decreased, it still met the indicators and the economic benefits were obvious.

[0059] Comparative Example 1

[0060] This comparative example is the same as the scheme of Example 1, except that the grooved spiral chute gravity separation process is removed. The final phosphate concentrate has a P2O5 grade of 25.75%, a recovery rate of 51.31%, and a Mg grade of 0.93%.

[0061] Comparative Example 2

[0062] This comparative example is the same as Example 1, except that the degypsum collector is replaced with sodium oleate. The final phosphate concentrate has a P2O5 grade of 22.51%, a recovery rate of 48.63%, and a Mg grade of 0.74%.

[0063] Comparative Example 3

[0064] This comparative example is the same as Example 1, except that the apatite flotation inhibitor is replaced with salinized water glass. The final phosphate concentrate has a P2O5 grade of 18.92%, a recovery rate of 58.66%, and a Mg grade of 0.84%.

[0065] Comparative Example 4

[0066] This comparative example is the same as Example 1, except that the apatite flotation collector is replaced with sodium oleate. The final phosphate concentrate has a P2O5 grade of 32.76%, a recovery rate of 36.71%, and a Mg grade of 0.79%.

[0067] Comparative Example 5

[0068] This comparative example is the same as Example 1, except that the concentrate regrinding process is removed. The final phosphate concentrate has a P2O5 grade of 21.72%, a recovery rate of 47.39%, and a Mg grade of 1.01%.

[0069] It can be seen from the comparative examples that the main function of the process of the present invention is to effectively remove impurities from ultra-low-grade, difficult-to-remove impurities apatite through a combined magnetic-gravity-flotation process, thereby ensuring the apatite yield while ensuring the quality of the apatite concentrate.

[0070] The examples described in the present invention are merely descriptions of the preferred implementation modes of the present invention, and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made to the technical solutions of the present invention by engineers and technicians in this field should all fall within the protection scope of the present invention.

Claims

1. A process for recovering apatite from iron ore tailings by flotation, characterized in that: The following steps are involved:

1. The tailings are subjected to high-gradient magnetic separation to recover and remove magnetic iron-containing minerals, and the removed iron-containing minerals are returned to the main iron selection process. The tailings enter the chute to remove large-particle gangue minerals, and then enter the thickening tank for concentration; 2. The bottom flow products of the thickening tank are successively subjected to sulfide ore flotation and gypsum flotation to remove interfering impurities, and then apatite capture positive flotation is carried out to obtain apatite concentrate; 3. The apatite concentrate is subjected to ultrafine grinding for dissociation and impurity selective mudification, and then the apatite is subjected to closed-circuit concentration to obtain a qualified apatite concentrate product.

2. A process for recovering apatite by flotation of iron ore tailings according to claim 1, characterized in that: In the step 1, the pulsation frequency is 100-200 r / min, the pulsation stroke is 5-15 mm, the magnetic induction intensity is 0.8-1.3 T, the slurry concentration is 10%-20%, and the +150 mesh in the fine-grained product of the chute is ≤5%.

3. A process for recovering apatite by flotation of iron ore tailings according to claim 1, characterized in that: In the step 2, the concentration of sulfide ore flotation is 25%-35%. During the process, copper sulfate, collector and 2# oil frother are added in sequence. The amount of copper sulfate is 70-130 g / t, the amount of collector is 70-130 g / t, and the amount of 2# oil frother is 15-20 g / t.

4. A process for recovering apatite by flotation of iron ore tailings according to claim 3, characterized in that: The collector for sulfide ore flotation is at least one of ethyl xanthate, butyl xanthate, black medicine, and thiamine ester.

5. A process for recovering apatite by flotation of iron ore tailings according to claim 1, characterized in that: In the step 2, a fatty acid collector MG is added during gypsum flotation, the dosage is 50-100 g / t, and the flotation time is 13-20 min; the fatty acid collector MG is obtained by saponifying 30-50 parts of modified oleic acid, 20-40 parts of long-chain alkanoic acid, 20-40 parts of long-chain olefinic acid, 10-20 parts of linoleic acid and 10-20 parts of isomeric alcohol polyoxyethylene ether.

6. A process for recovering apatite from iron ore tailings by flotation according to claim 5, characterized in that: Therefore, in step 2, a pH adjuster, a combined depressant YW and a combined collector 3S are added in sequence during apatite flotation, the pH adjuster needs to control the pH of the slurry to 8-10, the amount of the combined depressant is 1.3-1.8 kg / t, and the amount of the combined collector is 500-1000 g / t; the pH adjuster is a carbonate adjuster; the combined collector 3S is composed of 30-50 parts of a fatty acid collector MG, 30-50 parts of heavy alkylbenzene sulfonic acid and 10-20 parts of oxidized paraffin soap; the combined depressant YW is composed of 40-70 parts of water glass and 20-40 parts of organic cellulose.

7. A process for recovering apatite from iron ore tailings by flotation according to claim 6, characterized in that: In the step 3, when the apatite concentrate is subjected to ultrafine grinding for dissociation, the slurry concentration is controlled to be 40-60%, the grinding time is 1-4 minutes, and the grinding fineness is -200 mesh ≥98%.

8. A process for recovering apatite from iron ore tailings by flotation according to claim 7, characterized in that: In the step 3, the flotation column used for the closed-circuit concentration of apatite is at least one of an aerated flotation column, a microbubble countercurrent flotation column and a microbubble jet flotation column.

9. A process for recovering apatite from iron ore tailings by flotation according to claim 8, characterized in that: In the step 3, the number of closed-circuit concentrating passes of apatite is controlled to be 2-5.

10. A process for recovering apatite from iron ore tailings by flotation according to claim 9, characterized in that: The number of the cleaning passes is 3. In cleaning I, 20-50 g / t of combined collector 3S is first added, and then 50-100 g / t of combined inhibitor YW is added. In cleaning II, only 50-100 g / t of combined inhibitor YW is added. In cleaning III, only 20-50 g / t of combined inhibitor YW is added.

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