Collophanite dry separation method based on combination of color sorting and dense medium fluidized bed

Abstract

The invention discloses a collophanite dry sorting method based on combination of color sorting and a dense medium fluidized bed. According to the method, aiming at the defects of high environmental protection risk and insufficient single color sorting precision of existing wet sorting, efficient quality improvement of medium-low-grade collophanite is realized through a synergistic process of color sorting classification and dry-method dense medium fluidized bed enrichment: firstly, raw ore is crushed, concentrate, middling and tailings are obtained through two-stage color sorting classification, the concentrate is subjected to secondary color sorting, and the concentrate is subjected to secondary color sorting; the crushing size fraction is adjusted according to the content of phosphorus pentoxide, then an iron powder dense medium matched with the mineral particle size is adopted, and accurate separation is achieved through differentiated fluidization separation density. The whole process is free of water and chemical agents, the average grade of the concentrate reaches 20% or above, the phosphorus recovery rate is 80% or above, the environment-friendly requirements of ecological sensitive areas such as water sources are met, medium-low-grade resources can be fully utilized, the production cost is reduced, and the adaptability is wide.

Description

Technical Field

[0001] This invention relates to the field of mineral processing technology, specifically to a dry separation method for collophane, which is particularly suitable for the efficient separation and upgrading of medium and low grade collophane. Background Technology

[0002] Phosphate, a core carrier of my country's phosphorus resources, is mainly composed of fluoroapatite, an amorphous phosphate aggregate with a density ranging from 2.6 to 3.2 g / cm³. 3 my country has abundant collophane resources, but the endowment is poor, with an average grade of only 16.95%. It is mainly composed of medium and low grade ore, and the mineral forms are mostly massive, oolitic or nodular. It is often associated with gangue minerals such as gypsum, calcite, and dolomite. The symbiotic relationship between useful minerals and gangue is complex, which brings natural challenges to sorting and upgrading.

[0003] Currently, the mainstream sorting technologies for collophane in the industrial sector can be divided into two categories, both of which have unavoidable core limitations that severely restrict the efficient utilization of low- and medium-grade collophane resources. The first is the traditional wet sorting process, with flotation as a typical example. This process consumes a large amount of water and relies on various chemical reagents to separate minerals from gangue. Improper treatment of wastewater containing reagents and tailings generated during production can easily lead to eutrophication of surrounding water bodies, heavy metal and chemical pollution of soil, causing irreversible damage to the ecological environment. Crucially, many of my country's phosphate resources are located in water source protection areas, ecologically sensitive areas, and other areas with strict environmental controls. Such wet processes face policy constraints such as production restrictions, shutdowns, or even complete bans due to high environmental risks, resulting in a large amount of low- and medium-grade collophane resources being unable to be rationally developed. The second is the emerging dry photoelectric color sorting technology. While this technology completely eliminates dependence on water resources and achieves rapid sorting through surface color differences in ore, offering advantages such as a short process and low energy consumption, its sorting logic relies solely on surface optical characteristics. Due to the complex mineral composition of low- and medium-grade collophane, the color difference between some useful minerals and gangue is slight, and a large number of ores have internal inclusions and fine mineral grain size. Photoelectric color sorting is difficult to penetrate the surface of the ore to identify the true internal mineral composition, resulting in insufficient sorting accuracy and inability to obtain high-quality concentrate. It can only be used as a pre-selection waste disposal method to remove some obvious waste rock, which is difficult to meet the requirements of industrial production for concentrate grade.

[0004] In summary, existing technologies cannot simultaneously meet the dual core requirements of stringent environmental protection standards and high-precision sorting, especially in phosphate mining in special areas such as water source areas and ecological protection zones, where technological bottlenecks are even more pronounced. Therefore, developing a new sorting technology that is green, environmentally friendly, precise, and suitable for low- and medium-grade phosphate rock has become an urgent need for the industry, and is of great significance for improving the utilization rate of my country's phosphorus resources and ensuring the sustainable development of the phosphorus chemical industry. Summary of the Invention

[0005] To address the technical shortcomings of existing wet sorting processes, such as high environmental risks, and dry photoelectric color sorting, such as insufficient accuracy, this invention provides a dry sorting method for collophane based on a combination of color sorting and heavy medium fluidized bed. This method achieves green sorting without water or chemical reagents, while simultaneously ensuring sorting efficiency and accuracy, improving phosphorus resource recovery rate, and providing an effective solution for the development of medium- and low-grade collophane, especially phosphorus resources in ecologically sensitive areas.

[0006] To achieve the above objectives, the present invention provides a dry separation method for phosphate rock based on a combination of color sorting and heavy medium fluidized bed, comprising the following steps: S1. Preparation of raw ore for color sorting: Crush the raw collophane ore into blocky ore product R1 with a particle size of 50-100mm; S2, Color sorting of raw ore: Color sorting is performed on the ore product R1 to separate concentrate C1, middlings M1 and tailings T1; S3. Concentrate re-selection: The concentrate C1 is subjected to color sorting again to separate concentrate C2 and tailings T2. S4. Crushing process: The color sorting concentrate C2, middlings M1 and tailings T2 are crushed respectively; S5. Fluidized bed separation: Dry heavy medium fluidized bed separation is used to separate the crushed concentrate C2, middlings M1 and tailings T2 to obtain the final concentrate and tailings.

[0007] Furthermore, in step S2, a color sorter is used for separation. The grayscale value G1 of the first stage of separation is set to a range of 20-35, and the grayscale value G2 of the second stage of separation is set to a range of 35-70. The first stage of separation yields concentrate C1, and the remaining material is separated into middlings M1 and tailings T1 by the second stage of separation. Grayscale value is the core parameter for the color sorter to identify the depth of mineral color; the lower the value, the darker the corresponding mineral color; the higher the value, the lighter the corresponding mineral color. High-grade (phosphorus-rich) ores are usually darker in color, possibly dark gray or blackish-brown, with low surface reflectivity and corresponding smaller grayscale values. Low-grade ores or middlings are relatively lighter in color and may contain more light-colored gangue (such as calcite or dolomite), with higher reflectivity and corresponding medium grayscale values. Waste rock (tailings), such as pure calcite or quartz gangue, is usually very light in color (grayish-white or white), with high reflectivity and corresponding larger grayscale values. The first stage of sorting (G1: 20-35) directly separates the highest-quality, phosphate-rich ore with the darkest color and most distinctive appearance from the raw ore. Setting the threshold in the lower 20-35 range means that the color sorter only identifies and ejects ores with very dark colors (grayscale values ​​below 35) as concentrate C1. This is equivalent to setting a very strict optical threshold, ensuring that the concentrate obtained in the first process has the highest appearance quality and a high initial grade. The second stage of sorting (G2: 35-70) performs a secondary sorting on the remaining material that was not selected in the first stage (all with grayscale values ​​> 35), distinguishing between valuable middlings and essentially worthless waste rock. The upper limit of the grayscale threshold for the second stage is set at 70. For ores with grayscale values ​​between 35 and 70, their color is medium, and they may be formed by the symbiosis or inclusion of some phosphate minerals with light-colored gangue, still containing some value.

[0008] Furthermore, in step S4, the crushing particle size is adjusted according to the phosphorus pentoxide content in the material: If the phosphorus pentoxide content is greater than 28%, then no crushing is required, and the particle size should be kept between 100-50 mm. If the phosphorus pentoxide content is between 22-28%, then crush it to 50-25mm. If the phosphorus pentoxide content is less than 22%, then crush it to 25-13mm.

[0009] A phosphorus pentoxide (PPO) content greater than 28% indicates a high-grade ore with extremely high quality. Deep liberation is unnecessary; materials with PPO content exceeding 28% are already considered high-quality, high-grade ore blocks. The main minerals likely exist as large individual particles or enriched aggregates, with clear boundaries between them and gangue. Crushing at this stage not only has limited effect on further liberation but may also damage the naturally enriched, high-value ore blocks. Maintaining large block sizes is beneficial for maintaining high separation efficiency when used as a direct product or as feed for heavy media separation. Simultaneously, skipping the crushing stage significantly saves energy consumption, equipment wear, and operation time, making it the most cost-effective option. Crushing produces fine mud, which is difficult to handle effectively in subsequent dry separation (especially heavy media fluidized bed separation), easily leading to the loss of valuable minerals.

[0010] The phosphorus pentoxide content is between 22-28%. Materials in this grade range are typically C2 concentrates containing a significant proportion of useful minerals, but also containing a certain amount of gangue. Crushing to a medium particle size of 50-25mm can break up some of the intergrowths, releasing more monomeric phosphorus minerals. This creates better conditions for further precise separation based on density differences using a heavy media fluidized bed. Simultaneously, this particle size range is the golden range for dry heavy media separation. If the particle size is too coarse, liberation is insufficient, and separation accuracy is low; if the particle size is too fine, the surface area of ​​the material increases, easily generating dust in the fluidized bed, interfering with the fluidization state, and increasing the difficulty of recovering the separation medium. A particle size of 50-25mm can well balance the liberation requirements with the stability and efficiency of the separation process.

[0011] If the phosphorus pentoxide content is below 22%, the material value in this grade range is low, with a high gangue content. Valuable minerals may be finely embedded or closely associated with the gangue. To achieve economical recovery, more thorough crushing is necessary, reducing the material to a finer particle size of 25-13 mm. This aims to maximize the individual liberation of phosphorus minerals from the gangue. Only with sufficient liberation can the subsequent dry heavy-medium fluidized bed process effectively extract the tiny phosphorus mineral particles from the large amount of light gangue based on the significant density difference between them. This purifies the low-grade material into a valuable concentrate, significantly improving the overall phosphorus recovery rate and turning waste into treasure.

[0012] Furthermore, in step S5, when the crushed concentrate C2 is subjected to fluidized bed separation, the selected heavy medium is iron powder, the particle size of which matches the particle size of the crushed concentrate C2. The matching relationship between the particle size of the heavy medium iron powder and the mineral particle size is as follows: When the mineral particle size is 100-50mm, the iron powder particle size is 160-250μm; When the mineral particle size is 50-25mm, the iron powder particle size is 100-180μm; When the mineral particle size is 25-13 mm, the iron powder particle size is 80-150 μm.

[0013] The core of dry heavy media fluidized bed separation is to suspend heavy media (iron powder) through airflow, forming an artificial heavy liquid layer with uniform density and fluid properties. After mineral particles enter this medium layer, they stratify based on the difference in density between themselves and the medium layer. The key conditions for this process are that the heavy media must form a stable and uniform fluidized layer, and that the mineral particles can freely settle / float within the medium layer without being adsorbed or entrained by other medium particles. Therefore, the particle size of the heavy media must be compatible with the particle size of the minerals to ensure the fluidization stability of the medium layer while avoiding separation failure due to size mismatch between the minerals and the medium.

[0014] Coarse-grained minerals (100-50mm) are large in quantity and volume. If excessively fine iron powder is used, it is easily over-suspended under airflow, forming dilute phase fluidization, resulting in uneven density of the medium layer. Furthermore, the fine iron powder is easily carried away by the airflow, making it impossible to form a stable artificial heavy liquid layer. If an excessively coarse medium is used, extremely high airflow velocities are required to suspend the medium, not only increasing energy consumption but also potentially causing the coarse-grained minerals to be entrained by the airflow due to excessive airflow intensity, preventing them from settling and stratifying normally. Iron powder particles (160-250μm) fall into the coarse medium category. Under suitable airflow velocities, they can form dense phase fluidization, with uniform suspension and stable density of medium particles. They can also support the weight of coarse-grained minerals through the supporting force between the particles themselves, preventing mineral particles from directly depositing to the bottom and disrupting the fluidization layer. This ensures that the coarse-grained minerals fully respond to density differences within the medium layer. Coarse-grained minerals have a small specific surface area, and coarse iron powder of 160-250μm has few contact points with the mineral surface, making it less likely to be adsorbed onto the mineral surface by van der Waals forces. At the same time, the gaps between coarse media particles are relatively large, and airflow can form stable channels through the gaps, promoting rapid stratification of mineral particles and avoiding sorting delays caused by fine media clogging the pores on the mineral surface, thus improving the processing efficiency of coarse-grained minerals.

[0015] Medium-grained minerals (50-25mm) fall between coarse and fine grains. The fluidizing medium needs to possess the stability required for coarse-grained separation while also accommodating the localized encapsulation of valuable minerals and gangue in medium-grade ores. A more uniform medium density is needed to identify density differences within the minerals. Iron powder particles (100-180μm) are finer than those suitable for coarse-grained media, resulting in a more delicate density gradient after fluidization. This avoids the problem of large density fluctuations in coarse media and accurately responds to localized high and low density differences within medium-grained minerals, preventing misjudgments due to uneven medium density. Simultaneously, the fluidization of this particle size requires a moderate airflow velocity, preventing excessive suspension of medium-grained minerals due to excessive airflow or media deposition due to insufficient airflow.

[0016] Fine-grained minerals (25-13mm) mostly correspond to low-grade ore. Useful minerals exist as fine-grained embedded, diffusely distributed, or encapsulated within gangue. The density differences between individual mineral particles are even more subtle, requiring a finer medium layer to capture these subtle differences. Fine iron powder (80-150μm) has a large specific surface area, resulting in a denser and more uniform medium layer after fluidization. Once fine-grained mineral particles enter, they can fully contact the medium layer, amplifying even subtle density differences and achieving precise separation of fine-grained useful minerals from gangue. If a coarse medium is used, the gaps between the medium layers are too large, and fine-grained minerals may become embedded in the gaps between medium particles, unable to settle or float freely, leading to separation failure. Fine-grained minerals are also small in quantity and easily carried away by airflow. The dense fluidized layer formed by fluidizing 80-150μm fine iron powder has a certain viscosity and stronger interparticle interaction, which can create a hindrance effect on fine minerals and prevent them from rising and being lost rapidly with the airflow. At the same time, the particle size difference between the fine medium and the fine minerals is moderate, and the separation of fine iron powder and fine minerals is easy when the heavy medium is recovered by magnetic separation. This avoids the separation difficulties caused by the similar particle size of the fine medium and the fine minerals, which ensures the separation accuracy and reduces the loss of heavy medium.

[0017] Furthermore, in step S5, when the crushed concentrate C2 is subjected to fluidized bed separation, the fluidized bed separation density is controlled at 2.8-3.0 g / cm³. 3 When performing fluidized bed separation on the crushed middlings M1 and tailings T2, the fluidized bed separation density is controlled at 2.7-2.9 g / cm³. 3 .

[0018] Furthermore, in step S5, the crushed concentrate C2 is subjected to fluidized bed separation to separate phosphorus-containing concentrate C3 and tailings T3; the crushed middlings M1 and tailings T2 are subjected to fluidized bed separation to separate concentrate C4 and tailings T4.

[0019] Furthermore, in step S2, the phosphorus pentoxide content of concentrate C1 is greater than 18%, the phosphorus pentoxide content of middlings M1 is 12%-18%, and the phosphorus pentoxide content of tailings T1 is less than 8%; in step S3, the phosphorus pentoxide content of concentrate C2 is greater than 20%, and the phosphorus pentoxide content of tailings T2 is less than 20%.

[0020] Furthermore, in step S5, the phosphorus pentoxide content of concentrate C3 is 20%-30%, and the phosphorus pentoxide content of tailings T3 is less than 15%; the phosphorus pentoxide content of concentrate C4 is 15%-24%, and the phosphorus pentoxide content of tailings T4 is less than 12%. On the other hand, the present invention also provides a collophane concentrate product obtained by sorting according to the above method, which is prepared by a combined process of anhydrous color sorting and dry heavy medium fluidized bed, and its phosphorus pentoxide content is not less than 20%.

[0021] The beneficial effects of this invention are: (1) This invention creatively combines the advantages of color sorting and heavy medium fluidized bed. In the color sorting stage, a large amount of low-grade waste rock is quickly removed, reducing the load on subsequent processing. The fluidized bed achieves deep enrichment based on density differences, making up for the shortcomings of single color sorting, which only identifies the surface and has difficulty distinguishing the interior. The final average grade of the concentrate is much higher than that of the single color sorting process, and high-quality concentrate can be produced stably. Through the closed-loop design of color sorting grading, crushing particle size adjustment according to grade, and differentiated sorting density, the useful minerals in medium and low grade ores and middlings are effectively recovered. Even for low-grade raw ore with a phosphorus pentoxide content of 16.8%, the phosphorus recovery rate is still 80.1%, which is significantly higher than that of the single color sorting process, greatly improving the utilization rate of medium and low grade phosphate rock resources in my country.

[0022] (2) The entire process adopts a dry process, which eliminates the need for water and chemical reagents, thereby preventing wastewater discharge, eutrophication of water bodies, and soil pollution from the source. It is particularly suitable for areas with strict environmental control, such as water source protection areas and ecologically sensitive areas, breaking the application limitations of traditional wet processes and realizing the green development of collophane. It does not consume water resources and chemical reagents, saving water fees, reagent procurement costs, and wastewater treatment costs; the recovery rate of heavy media iron powder is over 98.5%, which can be recycled, reducing media loss; the crushing particle size is adjusted according to grade differences to avoid energy waste and equipment wear caused by excessive crushing, and the unit processing cost is lower than that of traditional wet flotation processes. The process can cover medium and low grade collophane with phosphorus pentoxide content of 15%-21%, and can effectively separate typical medium and low grade ores, medium and high grade fluctuating ores, and low grade limit ores. Without requiring major adjustments to core equipment, it can be adapted simply by fine-tuning grayscale values, crushing particle size, and sorting density, meeting the industrial production needs of different mining areas and raw ores with different endowments. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments thereof. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0024] Example 1: Processing low- to medium-grade raw ore (P2O5 ~16.80%) Raw ore: collophane, phosphorus pentoxide (P2O5) content 16.80%, particle size 150-0mm.

[0025] Process parameters: S1 Crushing: The raw ore is crushed to 50-100mm to obtain blocky ore product R1.

[0026] S2 Color Sorting: A color sorter is used, with the first stage grayscale value G1=25 and the second stage grayscale value G2=55. Output: Concentrate C1 (P2O5 20.4%), yield 35%; Middlings M1 (P2O5 17.1%), yield 50%; Tailings T1 (P2O5 7.6%), yield 15%.

[0027] S3 re-sorting: C1 is sorted again, yielding: concentrate C2 (P2O5 22.5%), yield 63%; tailings T2 (P2O5 16.9%), yield 37%.

[0028] S4 crushing: C2 (P2O5 22.5%), crushed to 50-25mm; M1 (P2O5 17.1%) and T2 (P2O5 16.9%), both crushed to 25-13mm.

[0029] S5 fluidized bed separation: C2 (50-25mm) after crushing: Use iron powder heavy medium with a particle size of 100-180μm, fluidized bed separation density of 2.90 g / cm³. 3 .output: Concentrate C3 (P2O5 25.1%), yield 76%; Tailings T3 (P2O5 14.3%), yield 24%; After crushing, M1+T2 (25-13mm): Iron powder heavy medium with a particle size of 80-150μm is selected, and the fluidized bed separation density is 2.75 g / cm³. 3 Output: Concentrate C4 (P2O5 18.6%), yield 79%; tailings T4 (P2O5 11.4%).

[0030] Example 2: Processing raw ore with fluctuating grade Raw ore: P2O5 content 20.4%, particle size 200-0mm, uneven.

[0031] Key process points: After color sorting by S2 and S3, the yields are as follows: C1 (P2O5 24.6%), 45%; M1 (P2O5 17.9%), 50%; T1 (P2O5 7.9%), 5%; C2 (P2O5 27.2%), 73%; and T2 (P2O5 17.4%), 27%.

[0032] S4 crushing: C2 (P2O5 27.2%), crushed to 50-25mm; M1 (P2O5 17.9%), T2 (P2O5 17.4%), crushed to 25-13mm.

[0033] S5 sorting: C2 after crushing: fluidized separation density 2.95 g / cm³ 3 The iron powder medium has a particle size of 100-180 μm. After crushing, the M1+T2 fluidized bed separation density is 2.75 g / cm³. 3 The iron powder medium has a particle size of 80-150μm.

[0034] Example 3: High-grade lump ore Raw ore: After preliminary hand sorting, some rich ore was obtained, with a P2O5 content of 26.0%.

[0035] Key points of the process: Preparation of raw ore for S1 color sorting: The particle size of the raw ore is already 80-60mm, and it is directly used as R1.

[0036] S2 raw ore color sorting: G1=22, G2=65, yield C1 (P2O5 26.9%), yield 95%; T1 (P2O5 8%), no medium ore M1.

[0037] S3 concentrate re-selection: C1 is re-color sorted to produce C2 (P2O5 28.1%), yield 86%; T2 (P2O5 19.5%).

[0038] S4 Crushing treatment: C2 (P2O5 28.1%), maintain the original particle size of 80-60mm, do not crush; T2 (P2O5 19.5%), crush to 25-13mm.

[0039] S5 Fluidized Bed Sorting: C2 (80-60mm) after crushing: Use iron powder heavy medium with a particle size of 160-200μm and a fluidized bed separation density of 3.0 g / cm³. 3 The yield was C3 (P2O5 29.6%), with a yield of 90%; and T3 (P2O5 14.8%). After crushing, T2 (25-13mm): iron powder medium particle size 80-150μm, fluidized separation density 2.85 g / cm³ 3 The output is C4 (P2O5 22.3%) and T4 (P2O5 11.4%).

[0040] Comparative Example 1: Process: Only two-stage color sorting (S2 and S3 in Example 1) is used, without subsequent crushing and fluidized bed separation. The color-sorted concentrate C2 is used as the final product.

[0041] Comparative Example 2: Process: Without color sorting pre-selection, the raw ore is uniformly crushed to 25-13mm and directly fed into a single fluidized bed separator. Other procedures are the same as in Example 1, with the separator density set at 2.85 g / cm³. 3 .

[0042] Comparative Example 3: Process: Example 1 is used, but the difference is that matching rules are not used. S4 Crushing: Regardless of grade, all materials (C2, M1, T2) are uniformly crushed to 25-13mm.

[0043] S5 sorting: Uses uniform fine iron powder (80-150μm) and uniform sorting density (2.8 g / cm³) for all fine-grained materials. 3 ).

[0044] Experimental Data Summary and Analysis

[0045] The experimental data above demonstrates that this invention successfully overcomes the limitations of single technologies by employing a tandem combination of color sorting for pre-waste removal and heavy media separation. Color sorting efficiently removes a large amount of low-value waste rock (T1), significantly reducing the processing load and cost of subsequent heavy media separation. Heavy media separation precisely addresses minerals that color sorting cannot distinguish—minerals with similar colors but different densities—achieving deep purification and recovery. This invention does not simply combine two technologies; rather, it utilizes a series of intelligent adaptation rules to determine crushing particle size based on grade, match media based on particle size, and determine separation density based on material properties, enabling the entire system to achieve optimal operation. Comparative Example 3 proves that disrupting these precise matching relationships significantly reduces overall performance. Compared to wet processes, this invention is entirely dry, without chemical reagents or wastewater, offering significant environmental advantages. Compared to other dry processes, this invention achieves the best balance in both concentrate grade and metal recovery rate, maximizing resource utilization while enhancing product value, resulting in significant economic benefits. By employing a differentiated sorting strategy of high-density purification of concentrate and low-density scavenging of middlings, this invention achieves maximum recovery of complex collophane resources. It is particularly suitable for medium- and low-grade, complexly disseminated, and difficult-to-process collophane, thus expanding the economically exploitable boundaries of phosphorus resources.

[0046] The embodiments described above are some, but not all, embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A dry separation method for phosphate rock based on a combination of color sorting and heavy medium fluidized bed, characterized in that, Includes the following steps: S1. Preparation of raw ore for color sorting: Crush the raw collophane ore into blocky ore product R1 with a particle size of 50-100mm; S2, Color sorting of raw ore: Color sorting is performed on the ore product R1 to separate concentrate C1, middlings M1 and tailings T1; S3. Concentrate re-selection: The concentrate C1 is subjected to color sorting again to separate concentrate C2 and tailings T2. S4. Crushing process: The color sorting concentrate C2, middlings M1 and tailings T2 are crushed respectively; S5. Fluidized bed separation: Dry heavy medium fluidized bed separation is used to separate the crushed concentrate C2, middlings M1 and tailings T2 to obtain the final concentrate and tailings.

2. The dry separation method for phosphate rock according to claim 1, characterized in that, In step S2, a color sorter is used for sorting. The gray value range of the first sorting stage G1 is set to 20-35, and the gray value range of the second sorting stage G2 is 35-70. The concentrate C1 is obtained after the first sorting stage, and the remaining material is sorted in the second stage to obtain middlings M1 and tailings T1.

3. The dry separation method for phosphate rock according to claim 1, characterized in that, In step S4, the crushing particle size is adjusted according to the phosphorus pentoxide content in the material: If the phosphorus pentoxide content is greater than 28%, then no crushing is required, and the particle size should be kept between 100-50 mm. If the phosphorus pentoxide content is between 22-28%, then crush it to 50-25mm. If the phosphorus pentoxide content is less than 22%, then crush it to 25-13mm.

4. The dry separation method for phosphate rock according to claim 1, characterized in that, In step S5, when the crushed concentrate C2 is subjected to fluidized bed separation, the heavy medium selected is iron powder, whose particle size matches the particle size of the crushed concentrate C2.

5. The dry separation method for phosphate rock according to claim 4, characterized in that, The matching relationship between the particle size of the heavy medium iron powder and the particle size of the mineral is as follows: When the mineral particle size is 100-50mm, the iron powder particle size is 160-250μm; When the mineral particle size is 50-25mm, the iron powder particle size is 100-180μm; When the mineral particle size is 25-13 mm, the iron powder particle size is 80-150 μm.

6. The dry separation method for phosphate rock according to claim 1, characterized in that, In step S5, when the crushed concentrate C2 is subjected to fluidized bed separation, the fluidized bed separation density is controlled at 2.8-3.0 g / cm³. 3 When performing fluidized bed separation on the crushed middlings M1 and tailings T2, the fluidized bed separation density is controlled at 2.7-2.9 g / cm³. 3 .

7. The dry separation method for phosphate rock according to claim 1, characterized in that, In step S5, the crushed concentrate C2 is subjected to fluidized bed separation to separate phosphorus-containing concentrate C3 and tailings T3; the crushed middlings M1 and tailings T2 are subjected to fluidized bed separation to separate concentrate C4 and tailings T4.

8. The dry separation method for phosphate rock according to claim 2, characterized in that, The phosphorus pentoxide content of concentrate C1 obtained in step S2 is greater than 18%, the phosphorus pentoxide content of middlings M1 is 12%-18%, and the phosphorus pentoxide content of tailings T1 is less than 8%; the phosphorus pentoxide content of concentrate C2 obtained in step S3 is greater than 20%, and the phosphorus pentoxide content of tailings T2 is less than 20%.

9. The dry separation method for phosphate rock according to claim 7, characterized in that, The phosphorus pentoxide content of concentrate C3 obtained in step S5 is 20%-30%, and the phosphorus pentoxide content of tailings T3 is less than 15%; the phosphorus pentoxide content of concentrate C4 is 15%-24%, and the phosphorus pentoxide content of tailings T4 is less than 12%.

10. A collophane concentrate product obtained by the method according to any one of claims 1-9, characterized in that, This product is prepared by a combined process of anhydrous color sorting and dry heavy medium fluidized bed, and its phosphorus pentoxide content is not less than 20%.

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