System for recovering iron and rare earth from iron-containing rare earth polymetallic ore and method of using the same

Abstract

A system for recovering iron and rare earth in iron-containing rare earth polymetallic ore and its use method, belonging to the field of beneficiation and comprehensive resource recovery. The system includes an oxidation decomposer, a multi-stage cyclone separator, an ore phase converter, a ball mill, a spiral classifier, a weak magnetic separator, a defluorination flotation machine corresponding to iron and rare earth, and a rare earth flotation machine. The use method is as follows: the iron-containing rare earth polymetallic ore is decomposed in the oxidation decomposer, and then separated, and a fluidized reduction chamber is provided to the ore powder in the ore phase converter to achieve efficient ore phase conversion, and after isolating the gas introduced with the ore powder in the previous stage, the ball mill is crushed, and then weak magnetic separation is performed by classification, and the obtained magnetic iron concentrate is subjected to "one coarse and one fine" closed-circuit defluorination reverse flotation, and the obtained magnetic tailings flotation is subjected to "one coarse and three fine" closed-circuit rare earth positive flotation. The system solves the difficulties of the complex mineral composition of the Bayan Obo lean oxide ore, the many associated valuable elements, and the similar beneficiation properties of the associated minerals.

Description

Technical Field

[0001] The present invention relates to the field of metallurgy and comprehensive resource recovery, and in particular to a system for recovering iron and rare earth from iron-containing rare earth polymetallic ores and a method for using the system. Background Art

[0002] The medium-poor oxidized stockpile of Bayan Obo is mainly composed of surface oxidized iron ore and some magnetite ore that could not be utilized in the early stage of Bayan Obo mine development. It is mainly fluorite iron ore. The rare earth grade (REO) in the mine is about 5.5%, and the fluorite content is more than 20%. The current stockpile is large and the stockpile time is long.

[0003] The main reasons why medium-poor oxidized ores are difficult to select are low iron grade, complex mineral composition, and fine embedded particle size. Due to long-term stacking, the ore has been weathered, soaked in water, and oxidized for a long time, and its surface properties have changed significantly, increasing the difficulty of recovery. In addition, the separation properties of many minerals, such as floatability, specific gravity, and specific magnetic susceptibility, are relatively close, so it is difficult to achieve effective recovery from the perspective of gravity separation, magnetic separation, or flotation.

[0004] CN112892848A discloses a beneficiation process for high-fluorine and high-phosphorus complex ores in Bayan Obo. The process uses a weak magnetic roughing-weak magnetic concentration-grinding-demuding-elution-iron reverse flotation process to recover iron concentrate, which reduces the F content in the iron concentrate and effectively improves the recovery index of the iron concentrate. However, the recovery target of this process is only for magnetic iron minerals, and the associated rare earths, fluorite and other minerals are not recovered; in addition, the process does not recover the iron in the weak magnetic tailings, which will lead to a decrease in the iron recovery rate and will also have a certain impact on the subsequent recovery of rare earths and fluorite.

[0005] CN105154659A discloses a method for simultaneously extracting iron and niobium from low-grade ore in Bayan Obo. Niobium chloride is obtained by adopting a method of high-temperature pretreatment-molten reduction-mixed quenching-chlorination treatment-condensation separation. However, this method is relatively complicated, energy-consuming, and the comprehensive recovery effect of valuable elements is not good. Summary of the invention

[0006] Based on the current situation that it is difficult to achieve efficient and comprehensive recovery of low-grade oxide ores in Bayan Obo with current processes and equipment, in order to solve the difficulties of complex mineral composition, many associated valuable elements and similar mineral processing properties of associated minerals in Bayan Obo poor oxide ore, the present invention proposes a system for recovering iron and rare earths from iron-containing rare earth polymetallic ores and a method for using the system.

[0007] A system for recovering iron and rare earth from an iron-containing rare earth polymetallic ore of the present invention comprises: a feed bin, a high-pressure roller mill, a venturi dryer, a first cyclone separator, a second cyclone separator, an oxidation decomposer, a third cyclone separator, a first fluidized sealing valve, an ore phase converter, a second fluidized sealing valve, a first cyclone cooler, a second cyclone cooler, a collecting bin, a ball mill, a spiral classifier, a weak magnetic separator, a first defluorination flotation machine, a first rare earth flotation machine, a second defluorination flotation machine, and a second rare earth flotation machine;

[0008] Among them, the discharge port of the feed bin is connected to the feed port of the high-pressure roller mill, the high-pressure roller mill is connected to the venturi dryer, the discharge port of the venturi dryer is connected to the feed port of the first cyclone separator, the discharge port of the first cyclone separator is connected to the feed port of the second cyclone separator, the discharge port of the second cyclone separator is connected to the feed port of the oxidation decomposer, the discharge port of the oxidation decomposer is connected to the feed port of the third cyclone separator through a pipeline, the discharge port of the third cyclone separator is connected to the first fluidizing sealing valve, the discharge port of the first fluidizing sealing valve is matched with the mineral phase converter, the discharge port of the mineral phase converter is connected to the second fluidizing sealing valve, the discharge port of the second fluidizing sealing valve is connected to the feed port of the first cyclone cooler The outlet of the first cyclone cooler is connected with the inlet of the second cyclone cooler, the outlet of the second cyclone cooler is opposite to the collecting bin, the collecting bin is connected to the ball mill, the discharge port of the ball mill is connected with the feed port of the spiral classifier, the overflow port of the spiral classifier is connected with the feed port of the weak magnetic separator through a pipeline, the concentrate discharge port of the weak magnetic separator is connected with the inlet of the first defluorination flotation machine, and the bottom discharge port of the first defluorination flotation machine is connected with the second defluorination flotation machine; the tailings discharge port of the weak magnetic separator is connected with the inlet of the first rare earth flotation machine, the foam product discharge port of the first rare earth flotation machine is connected with the second rare earth flotation machine, and the bottom discharge port of the second rare earth flotation machine is connected with the inlet of the first rare earth flotation machine through a pipeline.

[0009] Furthermore, the discharge port of the feed bin is opposite to the feed port of the screw feeder, and the discharge port of the screw feeder is opposite to the feed port of the high pressure roller mill.

[0010] Furthermore, the discharge port of the high pressure roller mill is opposite to the first feeding belt, and the discharge end of the first feeding belt is opposite to the feed port of the Venturi dryer.

[0011] Furthermore, the venturi dryer is connected to the drying heat generator, and a first ash hopper is provided between the connecting pipes of the venturi dryer and the drying heat generator.

[0012] Furthermore, a burner is provided at the bottom of the oxidation decomposer and is connected to a reducing gas source and an air source through a pipeline.

[0013] Furthermore, the discharge port of the collecting bin is opposite to the second feeding belt, and the discharge end of the second feeding belt is opposite to the ball mill.

[0014] In the above system, the top of the first cyclone separator is connected to the electrostatic precipitator through a pipeline, the electrostatic precipitator is connected to the tail gas absorption station, the tail gas absorption station and the induced draft fan cooperate, and the induced draft fan is connected to the chimney through a pipeline;

[0015] In the above system, the discharge port of the electrostatic precipitator is connected to the feed port of the pneumatic lift pump, the pneumatic lift pump is connected to the ash return fan, and the discharge port of the pneumatic lift pump is connected to the third cyclone separator through a pipeline;

[0016] In the above system, the top discharge port of the second cyclone cooler is connected to the first cyclone cooler through a pipeline, the top discharge port of the first cyclone cooler is connected to the third cyclone separator through a pipeline, the top discharge port of the third cyclone separator is connected to the second cyclone separator through a pipeline, and the top discharge port of the second cyclone separator is connected to the Venturi dryer through a pipeline;

[0017] In the above system, the discharge port of the first cyclone cooler is connected to the feed port of the second cyclone cooler through a pipeline, and a second ash hopper is also provided on the connecting pipeline.

[0018] In the above system, the dry heat generator is connected to the reducing gas source through a pipeline.

[0019] In the above system, the first fluidized sealing valve and the second fluidized sealing valve are both provided with air inlets at the bottom and are connected to the nitrogen gas source pipeline;

[0020] In the above system, an air inlet is provided at the bottom of the mineral phase converter and is connected to the reducing gas source pipeline, a ventilation port is provided at the top of the mineral phase converter and is connected to the feed port of the fourth cyclone separator, and the material is returned through the discharge port at the bottom of the fourth cyclone separator;

[0021] In the above system, the top discharge port of the fourth cyclone separator is connected to the oxidation decomposer;

[0022] In the above system, the return sand discharge port of the spiral classifier is connected to the ball mill to return the incompletely ball-milled materials for re-grinding.

[0023] In the above system, the foam product discharge port of the first defluorination flotation machine is connected to the defluorination tailings collection tank;

[0024] In the above system, the foam product of the second defluorination flotation machine is connected to the defluorination tailings collection tank through a pipeline;

[0025] In the above system, the bottom discharge port of the second defluorination flotation machine is connected to the iron concentrate collection tank;

[0026] In the above system, the bottom discharge port of the first rare earth flotation machine is connected to the rare earth tailings collection tank;

[0027] In the above system, the foam product discharge port of the second rare earth flotation machine is connected to the rare earth concentrate collection tank;

[0028] In the above system, the first defluorination flotation machine, the second defluorination flotation machine, the first rare earth flotation machine, and the second rare earth flotation machine are all equipped with corresponding pH online monitoring devices, temperature control devices, and pulp concentration detection devices;

[0029] In the above system, the oxidation decomposer, mineral phase converter and electrostatic precipitator are all equipped with temperature measuring devices and pressure sensing devices for monitoring the operating temperature and pressure.

[0030] The main function of the mineral phase converter is to provide a fluidized reduction chamber for mineral powder to achieve efficient mineral phase conversion. Its main body includes a mineral phase converter shell, forming a reduction chamber, and a mineral phase conversion feed port and a mineral phase conversion discharge port are arranged on the shell. A plurality of top baffles are arranged at intervals on the inner side of the shell located above, and a plurality of second bottom baffles are arranged staggered on the inner side of the shell located below, and a first bottom baffle is arranged directly below the top baffle, and a gap is left between the first bottom baffle and the corresponding top baffle. The top baffle and the first bottom baffle and the second bottom baffle together constitute a mineral powder flow channel, and the space formed between the top baffle and the second bottom baffle is a vertical channel; a mineral phase conversion air distribution plate is arranged on the shell on one side of the first bottom baffle and the second bottom baffle to evenly distribute the airflow; a mineral phase conversion air inlet is arranged in each vertical channel to provide loosening wind and fluidizing wind required for stable flow of mineral powder.

[0031] The main function of the first fluidized sealing valve and the second fluidized sealing valve is to isolate the gas introduced with the mineral powder in the previous stage. Its main body includes a fluidized sealing shell, which forms a fluidized chamber, a top fluidized sealing baffle is arranged above the fluidized chamber, a bottom fluidized sealing baffle is arranged directly below the top fluidized sealing baffle, and a fluidized sealing air distribution plate is arranged on one side of the bottom fluidized sealing baffle to evenly distribute the airflow; a nitrogen inlet is arranged in each vertical channel to provide loosening air and fluidizing air required for the stable flow of mineral powder.

[0032] The method for using the system for recovering iron and rare earth from iron-containing rare earth polymetallic ore of the present invention is carried out according to the following steps:

[0033] S1: crush the iron-containing rare earth polymetallic ore to less than 50 mm, transport it to the high pressure roller mill through a screw feeder and crush it to a particle size of ≤3 mm to obtain ore powder;

[0034] S2: Start the induced draft fan to generate negative pressure in the tail gas absorption station, the electrostatic precipitator, the first cyclone separator, the second cyclone separator, the oxidation decomposer, and the third cyclone separator; the combustion flue gas is introduced into the Venturi dryer to dry, dehydrate and preheat the mineral powder. The temperature of the preheated mineral powder is 150-200°C;

[0035] S3: sending the preheated mineral powder to the first cyclone separator and the second cyclone separator for separation in sequence, and sending the bottom material of the second cyclone separator to the oxidation decomposer; wherein the material entering the oxidation decomposer meets the particle size>40μm;

[0036] The flue gas formed by the mixed gas of air and reducing gas introduced into the burner is introduced into the air inlet at the bottom of the oxidation decomposer, so that the materials in the oxidation decomposer are oxidized and decomposed and are in a suspended state, and the oxidation decomposition temperature is 450-750°C, and the residence time is 2-10 minutes, so as to obtain suspended oxidation decomposition ore powder;

[0037] S4: After the suspended oxidation decomposition of the ore powder is cyclone separated, the bottom material is sealed in the first fluidized sealing valve to isolate the air and oxygen, and then mixed with the reducing gas and introduced into the ore phase converter for ore phase conversion to obtain the converted ore powder;

[0038] In the process of mineral phase conversion, the temperature is controlled at 430-550°C and the residence time is 20-90 minutes; the introduced reducing gas is one or a mixed reducing gas composed of H2, CO, methane, natural gas and coal-based gas; if the mixed reducing gas contains H2, the volume ratio of H2 in the mixed reducing gas is ≥55%;

[0039] S5: The converted mineral powder is sealed by the second fluidized sealing valve to isolate the reducing gas, and then is cooled to 150-200° C. by heat exchange through the first cyclone cooler and the second cyclone cooler to obtain cooled mineral powder;

[0040] S6: After the cooled ore powder is ball-milled in a ball mill, it is discharged into a spiral classifier and classified according to the different specific gravities of the ore powder, wherein the mass percentage of the ore powder with a particle size of -74 μm accounts for 80-96 wt % and is discharged into a weak magnetic separator for weak magnetic separation, with a magnetic field strength of 2300-4500 Oe, to obtain magnetically separated iron ore concentrate and magnetically separated tailings;

[0041] S7:

[0042] (1) The magnetically separated iron concentrate is used as a flotation mineral, the slurry is adjusted and an iron flotation agent is added, and a defluorination reverse flotation roughing is performed in a first defluorination flotation machine, the reverse flotation roughing temperature is controlled at 20 to 40° C., and the mass concentration of the magnetically separated iron concentrate slurry is controlled at 30 to 40 wt %, to obtain reverse flotation tailings and reverse flotation concentrate;

[0043] The reverse flotation concentrate enters the second defluorination flotation machine for defluorination reverse flotation concentration to obtain iron concentrate;

[0044] (2) The magnetic tailings are used as flotation minerals, slurried, and rare earth flotation reagents are added to the first rare earth flotation machine for rare earth direct flotation roughing, the direct flotation temperature is controlled at 40-70° C., and the magnetic tailings slurry concentration is controlled at 35-55wt%, to obtain roughing concentrate and roughing tailings;

[0045] The rougher concentrate is passed into the second rare earth flotation machine for rare earth positive flotation selection to obtain rare earth concentrate.

[0046] In the above method, in S3, the preheated mineral powder is separated from the waste gas and dust by the first cyclone separator, wherein the waste gas is discharged after purification, and the dust is collected by the electrostatic precipitator.

[0047] In the above method, in S3, the flue gas generated during the operation of the oxidation decomposer used for oxidation decomposition is returned to the Venturi dryer through a pipeline via the third cyclone separator and the second cyclone separator to realize waste heat utilization;

[0048] In the above method, in S3, during the oxidation decomposition process, the main reaction of the iron-containing rare earth polymetallic ore is:

[0049] Fe2O3·nH2O→α-Fe2O3+nH2O

[0050] 4FeCO3+O2→2α-Fe2O3+4CO2

[0051] 4Fe3O4+O2→6α-Fe2O3

[0052] CeCO3F→CeOF+CO2

[0053] In the above method, in S4, during the mineral phase transformation process, the main reaction of the iron-containing rare earth polymetallic ore is:

[0054] 3Fe2O3+CO→2Fe3O4+CO2

[0055] 3Fe2O3+H2→2Fe3O4+H2O

[0056] 2CeOF+H2O→Ce2O3+2HF

[0057] In the above method, in S5, during the heat exchange cooling process, the main reaction of the iron-containing rare earth polymetallic ore is:

[0058] 4Fe3O4+O2→6γ-Fe2O3

[0059] 14 / 3Ce2O3+O2→4 / 3Ce7O 12

[0060] In the above method, monazite and fluorite do not participate in the reaction during the mineral phase transformation process.

[0061] In the above method, in S4, the excess reducing gas in the mineral phase converter carries part of the mineral powder through the fourth cyclone separator for classification, the fine-grained dust returns to the oxidation decomposer with the reducing gas to continue to participate in the circulation, and the coarse-grained mineral powder returns to the mineral phase converter to enter the next step.

[0062] In the above method, in S5, the converted mineral powder is separated from dust gas during the heat exchange cooling process and mixed with the suspended oxidation decomposition mineral powder;

[0063] In the above method, in S5, the heat exchange cooling adopts a two-stage heat exchange cooling, and the dust and gas obtained after the second-stage heat exchange cooling separation are returned to the first-stage heat exchange cooling separation;

[0064] In the above method, in S6, the returned sand obtained by classification is sent back to the ball mill for regrinding.

[0065] In the above method, in S7, the magnetic iron concentrate flotation is a "one coarse and one fine" closed-circuit defluorination reverse flotation operation.

[0066] In the above method, in S7, the magnetic tailings flotation is a "one coarse and three fine" closed-circuit rare earth positive flotation operation.

[0067] In the above method, in S7, the reverse flotation reagents used in the defluorination reverse flotation roughing include a reverse flotation inhibitor and a reverse flotation collector, the reverse flotation inhibitor is water glass, the amount of which is 0.5-1.5 kg / t, and the reverse flotation collector is sodium oleate, the amount of which is 0.04-1.2 kg / t.

[0068] In the above method, in S7, the positive flotation reagents used in the roughing of rare earth positive flotation include positive flotation inhibitor, positive flotation collector and frother, the positive flotation inhibitor is water glass, the dosage is 0.1-4 kg / t, the positive flotation collector is hydroxamic acid, the dosage is 0.15-5.5 kg / t, and the frother is 2# oil, the dosage is 0.01-0.1 kg / t.

[0069] Compared with the existing process for treating iron-containing rare earth polymetallic ores, the system and method for using the system for recovering iron and rare earth from iron-containing rare earth polymetallic ores of the present invention have the following beneficial effects:

[0070] The present invention realizes the directional transformation - magnetic separation - flotation upgrading of weakly magnetic iron minerals in medium-lean ores through hydrogen-based mineral phase transformation technology, so that the difficult-to-select iron-containing components can be effectively enriched and recovered; the hydrogen-based mineral phase transformation technology adopted by the present invention can reduce CO2 emissions while avoiding carbon adsorption on the mineral surface caused by insufficient combustion, thereby causing the floatability of rare earth and fluorite components to decrease, ensuring the recovery effect of subsequent flotation operations; in addition, the present invention can realize the comprehensive recovery of valuable components in lean oxide ores, and can achieve effective enrichment of iron and rare earths. The fluorite-rich tailings obtained by flotation can also be recovered by flotation enrichment, and the product has high added value and significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 This is a schematic diagram of the structure of a system for recovering iron and rare earth from iron-containing rare earth polymetallic ores according to the present invention;

[0072] In the figure, 1. feeding bin, 2. screw feeder, 3. high pressure roller mill, 4. first feeding belt, 5. venturi dryer, 6. first cyclone separator, 7. second cyclone separator, 8. oxidation decomposer, 9. burner, 10. third cyclone separator, 11. first fluidization sealing valve, 12. mineral phase converter, 13. fourth cyclone separator, 14. second fluidization sealing valve, 15. first cyclone cooler, 16. second cyclone cooler, 17. collecting bin, 18. second feeding belt, 19. ball mill, 20. spiral classifier, 21. Weak magnetic separator, 22. First stirring barrel, 23. Second stirring barrel, 24. First defluorination flotation machine, 25. First rare earth flotation machine, 26. Second defluorination flotation machine, 27. Second rare earth flotation machine, 28. Defluorination tailings collecting tank, 29. Rare earth tailings collecting tank, 30. Iron concentrate collecting tank, 31. Rare earth concentrate collecting tank, 32. Electrostatic precipitator, 33. Tail gas absorption station, 34. Induced draft fan, 35. Chimney, 36. Pneumatic lift pump, 37. Ash return fan, 38. First ash hopper, 39. Second ash hopper, 40. Dry heat generator.

[0073] Figure 2 A schematic diagram of an ore phase converter device of a system for recovering iron and rare earth from iron-containing rare earth polymetallic ores according to the present invention;

[0074] In the figure, 12-1. mineral phase conversion feed inlet, 12-2. feed inlet stop valve, 12-3. mineral phase conversion discharge port, 12-4. reduction chamber, 12-5. mineral phase conversion air distribution plate, 12-6. top baffle, 12-7. first bottom baffle, 12-8. mineral phase conversion air inlet, 12-9. air inlet stop valve, 12-10. second bottom baffle.

[0075] Figure 3 A schematic diagram of a fluidized sealing valve device of a system for recovering iron and rare earth from iron-containing rare earth polymetallic ores according to the present invention;

[0076] In the figure, 11-1. feed inlet, 11-2. discharge port, 11-3. top fluidizing sealing baffle, 11-4. fluidizing chamber, 11-5. fluidizing sealing air distribution plate, 11-6. bottom fluidizing sealing baffle, 11-7. nitrogen inlet stop valve, 11-8. nitrogen inlet. DETAILED DESCRIPTION

[0077] In the iron-containing rare earth polymetallic ore of the embodiment of the present invention, TFe is 26.0% to 31.0%, REO is 4.2% to 6.5%, and CaF2 is 17.3% to 26.0%;

[0078] The present invention is further described below in conjunction with the accompanying drawings and examples. The equipment, reagents and materials described in the following examples, unless otherwise specified, can all be obtained from commercial channels; the test methods described, unless otherwise specified, are all conventional methods.

[0079] Example 1

[0080] A system for recovering iron and rare earth from iron-containing rare earth polymetallic ore, the schematic diagram of which is shown in FIG. Figure 1 As shown, it includes a feeding bin 1, a screw feeder 2, a high-pressure roller mill 3, a first feeding belt 4, a venturi dryer 5, a first cyclone separator 6, a second cyclone separator 7, an oxidation decomposer 8, a burner 9, a third cyclone separator 10, a first fluidizing sealing valve 11, an ore phase converter 12, a fourth cyclone separator 13, a second fluidizing sealing valve 14, a first cyclone cooler 15, a second cyclone cooler 16, a collecting bin 17, a second feeding belt 18, a ball mill 19, a spiral classifier 20, a weak magnetic separator 21, a first mixing barrel 22, a second mixing barrel 23, a first defluorination flotation machine 24, a first rare earth flotation machine 25, a second defluorination flotation machine 26, and a second rare earth flotation machine 27;

[0081] The discharge port of the feed bin 1 is opposite to the feed port of the screw feeder 2, the discharge port of the screw feeder 2 is opposite to the feed port of the high-pressure roller mill 3, the discharge port of the high-pressure roller mill 3 is opposite to the first feeding belt 4, the discharge end of the first feeding belt 4 is opposite to the feed port of the venturi dryer 5, the discharge port of the venturi dryer 5 is connected to the feed port of the first cyclone separator 6, the discharge port of the first cyclone separator 6 is connected to the discharge port of the second cyclone separator 7, the second cyclone separator 7 is connected to the feed port of the oxidation decomposer 8, and the bottom of the oxidation decomposer 8 is provided with a burner 9 and is connected through a pipeline. The reducing gas source and the air source are provided, the discharge port of the oxidation decomposer 8 is connected with the feed port of the third cyclone separator 10 through a pipeline, the discharge port of the third cyclone separator 10 is connected with the first fluidized sealing valve 11, the discharge port of the first fluidized sealing valve 11 is matched with the mineral phase converter 12, the discharge port of the mineral phase converter 12 is connected with the second fluidized sealing valve 14, the bottom of the mineral phase converter 12 is provided with an air inlet and is connected with the reducing gas source pipeline, the top of the mineral phase converter 12 is provided with a ventilation port and is connected with the feed port of the fourth cyclone separator 13, and the material is discharged through the bottom of the fourth cyclone separator 13. The material port returns; the top discharge port of the fourth cyclone separator 13 is connected to the oxidation decomposer 8; the discharge port of the second fluidized sealing valve 14 is connected to the feed port of the first cyclone cooler 15, the discharge port of the first cyclone cooler 15 is connected to the feed port of the second cyclone cooler 16, the discharge port of the second cyclone cooler 16 is opposite to the collecting bin 17, the discharge port of the collecting bin 17 is opposite to the second feeding belt 18, the discharge end of the second feeding belt 18 is opposite to the ball mill 19, the discharge port of the ball mill 19 is connected to the feed port of the spiral classifier 20, and the overflow port of the spiral classifier 20 is connected to the feed port of the weak magnetic separator 21 through a pipeline. The concentrate discharge port of the weak magnetic separator 21 is connected with the feed port of the first stirring barrel 22 through a pipeline, the tailings discharge port of the weak magnetic separator 21 is connected with the feed port of the second stirring barrel 23 through a pipeline, the first stirring barrel 22 is connected with the feed port 24 of the first defluorination flotation machine, the bottom discharge port of the first defluorination flotation machine 24 is connected with the second defluorination flotation machine 26, the second stirring barrel 23 is connected with the feed port of the first rare earth flotation machine 25, the foam product discharge port of the first rare earth flotation machine 25 is connected with the second flotation machine 27, and the bottom discharge port of the second rare earth flotation machine 27 is connected with the first rare earth flotation machine 25 through a pipeline.

[0082] The top of the first cyclone separator 6 is connected to the electrostatic precipitator 32 through a pipeline, the electrostatic precipitator 32 is connected to the tail gas absorption station 33, the tail gas absorption station 33 cooperates with the induced draft fan 34, and the induced draft fan 34 is connected to the chimney 35 through a pipeline;

[0083] The discharge port of the electrostatic precipitator 32 is connected to the feed port of the air lift pump 36, the air lift pump 36 is connected to the ash return fan 37, and the discharge port of the air lift pump 36 is connected to the third cyclone separator 10 through a pipeline;

[0084] The top discharge port of the second cyclone cooler 16 is connected to the first cyclone cooler 15 through a pipeline, the top discharge port of the first cyclone cooler 15 is connected to the third cyclone separator 10 through a pipeline, the top discharge port of the third cyclone separator 10 is connected to the second cyclone separator 7 through a pipeline, and the top discharge port of the second cyclone separator 7 is connected to the Venturi dryer 5 through a pipeline;

[0085] The dry heat generator 40 is connected to the reducing gas source through a pipeline, the Venturi dryer 5 is connected to the dry heat generator 40, and a first ash hopper 38 is provided between the connecting pipeline of the Venturi dryer 5 and the dry heat generator 40, and a second ash hopper 39 is provided on the pipeline between the first cyclone cooler 15 and the second cyclone cooler 16;

[0086] The first fluidized sealing valve 11 and the second fluidized sealing valve 14 are both provided with air inlets at the bottom and are connected to the nitrogen gas source pipeline;

[0087] The bottom of the mineral phase converter 12 is provided with a mineral phase conversion air inlet which is connected to the reducing gas source pipeline, and the top of the mineral phase converter 12 is provided with a ventilation port which is connected to the fourth cyclone separator 13;

[0088] The foam product discharge port of the first defluorination flotation machine 24 is connected to the defluorination tailings collection tank 28;

[0089] The foam product of the second defluorination flotation machine 26 is connected to the defluorination tailings collection tank 28 through a pipeline;

[0090] The bottom discharge port of the second defluorination flotation machine 26 is connected to the iron ore concentrate collecting tank 30;

[0091] The bottom discharge port of the first rare earth flotation machine 25 is connected to the rare earth tailings collection tank 29;

[0092] The foam product discharge port of the second rare earth flotation machine 27 is connected to the rare earth concentrate collection tank 31;

[0093] The first defluorination flotation machine 24, the second defluorination flotation machine 26, the first rare earth flotation machine 25, and the second rare earth flotation machine 27 are all equipped with a pH online monitoring device, a temperature control device, and a pulp concentration detection device;

[0094] The oxidation decomposer 8, the mineral phase converter 12 and the electrostatic precipitator 32 are all provided with temperature measuring devices and pressure sensing devices for monitoring the operating temperature and pressure.

[0095] Wherein, the structural schematic diagram of the mineral phase converter 12 is shown in Figure 2The main function of the fluidized reduction chamber is to provide a fluidized reduction chamber for the mineral powder to achieve efficient mineral phase conversion. The main body includes a mineral phase converter shell, forming a reduction chamber 12-4, a mineral phase conversion feed port 12-1 and a mineral phase conversion discharge port 12-3 are provided on the shell, a feed port stop valve 12-2 is provided on the pipeline where the mineral phase conversion feed port 12-1 is provided, a plurality of top baffles 12-6 are arranged at intervals on the inner side of the shell located above, a plurality of second bottom baffles 12-10 are arranged alternately on the inner side of the shell located below, and a first bottom baffle 12-7 is arranged directly below the top baffle 12-6, a gap is left between the first bottom baffle 12-7 and the corresponding top baffle 12-6, and the top baffle 12-6 and the first bottom baffle 12-10 are arranged at intervals on the inner side of the shell located below. The baffle 12-7 and the second bottom baffle 12-10 together constitute a mineral powder flow channel, and the space formed between the top baffle 12-6 and the second bottom baffle 12-10 is a vertical channel; a mineral phase conversion air distribution plate 12-5 is provided on the shell on one side of the first bottom baffle 12-7 and the second bottom baffle 12-10 to evenly distribute the airflow; a mineral phase conversion air inlet 12-8 is provided in each vertical channel, and an air inlet stop valve 12-9 is provided on the pipeline provided with the mineral phase conversion air inlet 12-8, and the mineral phase conversion air inlet 12-8 is used to provide loosening air and fluidizing air required for the stable flow of mineral powder.

[0096] The structural schematic diagram of the first fluidizing sealing valve 11 and the second fluidizing sealing valve 14 is shown in FIG. Figure 3 , the main function is to isolate the gas introduced with the mineral powder in the previous stage. Its main body includes a fluidized sealing shell, on which a feed port 11-1 and a discharge port 11-2 are arranged, and the fluidized sealing shell forms a fluidizing chamber 11-4, a top fluidized sealing baffle 11-3 is arranged above the fluidizing chamber, a bottom fluidized sealing baffle 11-6 is arranged below the fluidizing chamber, and a fluidized sealing air distribution plate 11-5 is arranged on one side of the bottom fluidized sealing baffle 11-6 for evenly distributing the airflow; a nitrogen inlet 11-8 is arranged in each vertical channel, and a nitrogen inlet stop valve 11-7 is arranged on the pipeline where the nitrogen inlet 11-8 is arranged, and the nitrogen inlet 11-8 is used to provide loosening air and fluidizing air required for the stable flow of mineral powder.

[0097] The method for using the system for recovering iron and rare earth from iron-containing rare earth polymetallic ores is carried out in the following steps:

[0098] 1. A certain dump of lean oxide ore, TFe 27.53%, REO 4.5%, CaF2 21.32%;

[0099] Crushing the iron-containing rare earth polymetallic ore to less than 50 mm and placing it in a feeding bin 1;

[0100] 2. The iron-containing rare earth polymetallic ore in the feed bin 1 is transported to the high pressure roller mill 3 through the screw feeder 2 and crushed to less than 1 mm to obtain ore powder;

[0101] 3. Start the induced draft fan 34 to generate negative pressure in the tail gas absorption station 33, the electrostatic precipitator 32, the first cyclone separator 6, the second cyclone separator 7, the oxidation decomposer 8, and the third cyclone separator 10; the reducing gas (H2 in this embodiment) enters the dry heat generator 40 for combustion, and the resulting ash enters the first ash hopper 38. The combustion flue gas is passed into the venturi dryer 5 to remove the adsorbed water of the mineral powder and preheat the material. The material temperature at the discharge port is 150°C;

[0102] 4. The prepared mineral powder is transported to the Venturi dryer 5 through the first feeding belt 4. After being dried and dehydrated, the mineral powder is sent to the first cyclone separator 6. After cyclone separation, the bottom material is sent to the oxidation decomposer 8 through the second cyclone separator 7; the dust separated in the first cyclone separator 6 enters the electrostatic precipitator 32 for capture, and the uncaptured smoke enters the exhaust gas absorption station 33. The smoke in the exhaust gas absorption station 33 is discharged into the atmosphere through the chimney 35 by the induced draft fan 34;

[0103] The flue gas captured by the electrostatic precipitator 32 enters the air lift pump 36 through its discharge port and returns to the third cyclone separator 10 through the ash return fan 37.

[0104] 5. The burner 9 generates flue gas by burning the air and reducing gas introduced, and the flue gas is introduced through the air inlet at the bottom of the oxidation decomposer 8, so that the material in the oxidation decomposer 8 is oxidized and decomposed and is in a suspended state. The material temperature is controlled at 650°C and the residence time is 8 minutes;

[0105] 6. The material after oxidation and decomposition enters the third cyclone separator 10. After cyclone separation, the bottom material enters the first fluidized sealing valve 11 to isolate air and oxygen. Then the material is introduced into the mineral phase converter 12. The mixed reducing gas is introduced into the mineral phase converter 12, so that the material is kept in a suspended state under the action of the mixed gas and undergoes mineral phase conversion. The material temperature is controlled at 450°C and the residence time is 50 minutes. The volume flow ratio of H2 and CO is 3:2.

[0106] 7. After the mineral phase conversion of the material, the reducing gas is isolated through the second fluidized sealing valve 14 and the mineral phase conversion product is discharged. The mineral phase conversion product is cooled to 150°C through heat exchange in the first cyclone cooler 15 and the second cyclone cooler 16 and then discharged into the collection bin 17; wherein, the material at the top of the mineral phase converter 12 enters the fourth cyclone separator 13 for separation, and the heavy material after separation returns through the bottom discharge port of the fourth cyclone separator 13, and the separated gas enters the oxidation decomposer 8;

[0107] 8. The ore powder in the collecting bin 17 is fed into the ball mill 19 through the second feeding belt 18. After being ground in the ball mill 19, the material is discharged into the spiral classifier 20. The material particle size is controlled to be -74 μm and the content is 93 wt%. Then, the material is discharged into the weak magnetic separator 21 for magnetic separation. The returned sand is returned to the ball mill for further grinding. The magnetic field strength is 3300 Oe, and magnetic concentrate and magnetic tailings are obtained.

[0108] 9. The magnetically separated iron concentrate is discharged into the first stirring barrel 22, and the flotation agent is added to stir and adjust the pulp, and then discharged into the first defluorination flotation machine 24 for defluorination reverse flotation roughing; the inhibitor used for defluorination reverse flotation is water glass, the dosage is 1.2kg / t, the collector is sodium oleate, the dosage is 0.4kg / t, the flotation temperature is controlled at 40°C, and the pulp concentration is controlled at 35wt%;

[0109] 10. The reverse flotation tailings (foam products) are introduced into the defluorination tailings collecting tank 28, and the reverse flotation concentrate (bottom materials) are introduced into the second defluorination flotation machine 26 for defluorination reverse flotation selection; the reverse flotation selection tailings (foam products) are introduced into the defluorination tailings collecting tank 28, and the reverse flotation selection concentrate (bottom materials) are introduced into the iron concentrate collecting tank 30, the TFe grade in the iron concentrate is 65.32%, the TFe recovery rate is 83.27%, the F grade is 0.38%, and the F recovery rate is 6.13%;

[0110] 11. The tailings from magnetic separation are discharged into the second stirring barrel 23, and the flotation reagent is added to stir and adjust the pulp, and then discharged into the first rare earth flotation machine 25 for rare earth roughing; the inhibitor used for rare earth flotation is water glass, the dosage is 2kg / t, the collector is hydroxamic acid, the dosage is 4.5kg / t, the frother is 2# oil, the dosage is 0.06kg / t, the flotation temperature is 60°C, and the pulp concentration is 50wt%;

[0111] 12. The rougher concentrate (foam product) is introduced into the second rare earth flotation machine 27 for rare earth selection, and the bottom material of the rougher tailings is introduced into the rare earth tailings collecting tank 29; the selected tailings (bottom material) are returned to the first rare earth flotation machine 25, and the selected concentrate (foam product) is introduced into the rare earth concentrate collecting tank 31. The REO grade in the rare earth flotation concentrate is 62.38%, and the REO recovery rate is 61.21%. The CaF2 grade in the fluorite-rich tailings is 54.12%. The rare earth tailings can further recover fluorite through flotation.

[0112] Example 2

[0113] A system for recovering iron and rare earth from iron-containing rare earth polymetallic ore, which is the same as Example 1, except that the method of use thereof is as follows:

[0114] 1. Crushing the iron-containing rare earth polymetallic ore to less than 50 mm and placing it in the feeding bin 1;

[0115] 2. The iron-containing rare earth polymetallic ore in the feed bin 1 is transported to the high pressure roller mill 3 through the screw feeder 2 and crushed to less than 3 mm to obtain ore powder;

[0116] 3. Start the induced draft fan 34 to generate negative pressure in the tail gas absorption station 33, the electrostatic precipitator 32, the first cyclone separator 6, the second cyclone separator 7, the oxidation decomposer 8, and the third cyclone separator 10; the reducing gas (H2 in this embodiment) enters the dry heat generator 40 for combustion, and the resulting ash enters the first ash hopper 38. The combustion flue gas is passed into the venturi dryer 5 to remove the adsorbed water of the mineral powder and preheat the material. The material temperature at the discharge port is 200°C;

[0117] 4. The prepared mineral powder is transported to the Venturi dryer 5 through the first feeding belt 4. After drying and dehydration, the mineral powder is sent to the first cyclone separator 6. After cyclone separation, the bottom material is sent to the oxidation decomposer 8 through the second cyclone separator 7. The fine dust (≤40μm) enters the exhaust gas treatment system with the flue gas;

[0118] 5. The burner 9 generates flue gas by burning the mixed gas of air and reducing gas. The flue gas contains generated H2O and CO2 as well as excess air. The flue gas is introduced through the air inlet at the bottom of the oxidation decomposer 8 to oxidize and decompose the materials in the oxidation decomposer 8 and put them in a suspended state. The material temperature is controlled at 500°C and the residence time is 5 minutes.

[0119] 6. The material after oxidation and decomposition enters the third cyclone separator 10. After cyclone separation, the bottom material enters the first fluidized sealing valve 11 to isolate air and oxygen. Then the material is passed into the mineral phase converter 12. The mixed reducing gas is passed into the mineral phase converter 12 to perform a loosening-fluidization process, so that the material remains in a suspended state under the action of the reducing gas and undergoes mineral phase conversion. The material temperature is controlled at 520°C and the residence time is 30 minutes; wherein the mixed reducing gas refers to a mixed gas of H2 and CO, and the volume proportion of H2 is 80%;

[0120] 7. After the mineral phase conversion of the material, the mixed reducing gas is isolated through the second fluidized sealing valve 14 and the mineral phase conversion product is discharged. The product is cooled to 150° C. through heat exchange in the first cyclone cooler 15 and the second cyclone cooler 16 and then discharged into the collection bin 17;

[0121] 8. The ore powder in the collecting bin 17 is fed into the ball mill 19 through the second feeding belt 18. After being ground in the ball mill 19, the material is discharged into the spiral classifier 20. The material particle size is controlled to be -74 μm and the content is 95 wt%. Then, the material is discharged into the weak magnetic separator 21 for magnetic separation. The magnetic field strength is 2500 Oe, and magnetic iron concentrate and magnetic tailings are obtained.

[0122] 9. The magnetically separated iron concentrate is discharged into the first stirring barrel 22, and the flotation agent is added to stir and adjust the pulp, and then discharged into the first defluorination flotation machine 24 for defluorination reverse flotation roughing; the flotation temperature is controlled at 30°C, and the pulp mass concentration is controlled at 32wt%;

[0123] 10. The reverse flotation tailings (foam products) are introduced into the defluorination tailings collection tank 28, and the reverse flotation concentrate (bottom material) is introduced into the second defluorination flotation machine 26 for defluorination reverse flotation selection; the reverse flotation selection tailings (foam products) are introduced into the defluorination tailings collection tank 28, and the reverse flotation selection concentrate (bottom material) is introduced into the iron concentrate collection tank 30;

[0124] 11. The tailings from magnetic separation are discharged into the second stirring barrel 23, and flotation reagents are added to stir and adjust the pulp, and then discharged into the first rare earth flotation machine 25 for rough rare earth selection; the flotation temperature is controlled at 50°C, and the pulp concentration is controlled at 45wt%;

[0125] 12. The rougher concentrate (foam product) is passed into the second rare earth flotation machine 27 for rare earth concentration, and the rougher tailings (bottom material) are passed into the rare earth tailings collection tank 29; the concentrated tailings (bottom material) are returned to the first rare earth flotation machine 25, and the concentrated concentrate (foam product) is passed into the rare earth concentrate collection tank 31;

[0126] In the above method, after the mineral powder is passed into the first cyclone separator 6, the separated dust is discharged into the electrostatic precipitator 32, and the flue gas after dust removal is passed into the tail gas absorption station 33 for purification treatment, and then discharged from the chimney 35;

[0127] In the above method, the dust collected by the electrostatic precipitator 32 is returned to the third cyclone separator 10 via the air lift pump 36 under the action of the dust return fan 37;

[0128] In the above method, the flue gas generated during the operation of the oxidative decomposer 8 is returned to the venturi dryer 5 through the pipeline via the third cyclone separator 10 and the second cyclone separator 7 to realize waste heat utilization;

[0129] In the above method, the dust and gas separated by the first cyclone cooler 15 are returned to the third cyclone separator 10;

[0130] In the above method, the dust and gas separated by the second cyclone cooler 16 are returned to the first cyclone cooler 15;

[0131] In the above method, the spiral classifier 20 classifies the ground material and then returns the sand to the ball mill 19 for further grinding.

[0132] Example 3

[0133] The system structure is the same as that of Example 1;

[0134] The method is the same as in Example 1, except that:

[0135] (1) TFe 31.56%, REO 4.23%, CaF2 21.38% in the original ore;

[0136] (2) The material temperature in the oxidation decomposer 8 is controlled at 600°C and the residence time is 10 minutes;

[0137] (3) The material temperature in the mineral phase converter 12 is controlled at 500° C. and the residence time is 60 min;

[0138] (4) The volume flow ratio of H2 to CO in the mineral phase converter 12 is 4:1;

[0139] (3) The mineral phase transformation product is ground to -74 μm and the content is 95 wt%; the weak magnetic separation magnetic field strength is 4000 Oe;

[0140] (4) In the reverse flotation defluorination operation, the amount of water glass used is 1.1 kg / t and the amount of sodium oleate is 0.2 kg / t;

[0141] (5) In the rare earth flotation operation, the pulp concentration is 45wt%, the flotation temperature is 45°C, the amount of water glass is 2.0kg / t, the amount of hydroxamic acid is 4.5kg / t, and the amount of 2# oil is 0.1kg / t;

[0142] (6) The TFe grade of the obtained iron concentrate is 64.51%, the TFe recovery rate is 90.33%, the F grade is 0.31%, and the F recovery rate is 9.93%. The REO grade of the rare earth flotation concentrate is 60.69%, and the REO recovery rate is 62.88%. The CaF2 grade of the fluorite-rich tailings is 51.89%. The rare earth tailings can be further recovered from fluorite by flotation.

[0143] Example 4

[0144] The system structure is the same as that of Example 1;

[0145] The method is the same as in Example 1, except that:

[0146] (1) TFe 27.68%, REO 5.98%, CaF2 20.56% in the original ore;

[0147] (2) The material temperature in the oxidation decomposer 8 is controlled at 550°C and the residence time is 5 minutes;

[0148] (3) The material temperature in the mineral phase converter 12 is controlled at 460° C. and the residence time is 45 min;

[0149] (4) The volume flow ratio of H2 to CO in the mineral phase converter 12 is 3:1;

[0150] (3) The mineral phase transformation product is ground to -74 μm and the content is 96 wt%; the weak magnetic separation magnetic field strength is 4300 Oe;

[0151] (4) In the reverse flotation defluorination operation, the amount of water glass used is 1.3 kg / t and the amount of sodium oleate is 0.45 kg / t;

[0152] (5) In the rare earth flotation operation, the pulp concentration is 47wt%, the flotation temperature is 55°C, the amount of water glass is 1.4kg / t, the amount of hydroxamic acid is 3.8kg / t, and the amount of 2# oil is 0.05kg / t;

[0153] (6) The TFe grade of the obtained iron concentrate is 65.66%, the TFe recovery rate is 86.42%, the F grade is 0.28%, and the F recovery rate is 10.23%. The REO grade of the rare earth flotation concentrate is 62.74%, and the REO recovery rate is 58.26%. The CaF2 grade of the fluorite-rich tailings is 50.33%. The rare earth tailings can be further recovered from fluorite by flotation.

[0154] Example 5

[0155] The system structure is the same as that of Example 1;

[0156] The method is the same as in Example 1, except that:

[0157] (1) TFe 29.50%, REO 5.03%, CaF2 19.65% in the original ore;

[0158] (2) The material temperature in the oxidation decomposer 8 is controlled at 700° C. and the residence time is 4.5 min;

[0159] (3) The material temperature in the mineral phase converter 12 is controlled at 430° C. and the residence time is 90 min;

[0160] (4) The volume flow ratio of H2 to CO in the mineral phase converter 12 is 3:1;

[0161] (3) The mineral phase transformation product is ground to -74 μm and the content is 91 wt%; the weak magnetic separation magnetic field strength is 3800 Oe;

[0162] (4) In the reverse flotation defluorination operation, the amount of water glass used is 1.2 kg / t and the amount of sodium oleate is 0.3 kg / t;

[0163] (5) In the rare earth flotation operation, the pulp concentration is 35wt%, the flotation temperature is 50°C, the amount of water glass is 1.8kg / t, the amount of hydroxamic acid is 4kg / t, and the amount of 2# oil is 0.05kg / t;

[0164] (6) The TFe grade of the obtained iron concentrate is 65.12%, and the TFe recovery rate is 85.64%. The F grade is 0.25%, and the F recovery rate is 8.65%. The REO grade of the rare earth flotation concentrate is 65.28%, and the REO recovery rate is 60.33%. The CaF2 grade of the fluorite-rich tailings is 52.33%. The rare earth tailings can be further recovered from fluorite by flotation.

[0165] Example 6

[0166] The system structure is the same as that of Example 1;

[0167] The method is the same as in Example 1, except that:

[0168] (1) TFe 28.36%, REO 6.12%, CaF2 22.33% in the original ore;

[0169] (2) The material temperature in the oxidation decomposer 8 is controlled at 450°C and the residence time is 7 minutes;

[0170] (3) The material temperature in the mineral phase converter 12 is controlled at 470° C. and the residence time is 60 min;

[0171] (4) The volume flow ratio of H2 to CO in the mineral phase converter 12 is 3:1;

[0172] (3) The mineral phase transformation product is ground to -74 μm and the content is 90 wt%; the weak magnetic separation magnetic field strength is 4000 Oe;

[0173] (4) In the reverse flotation defluorination operation, the amount of water glass used is 1.3 kg / t and the amount of sodium oleate is 0.35 kg / t;

[0174] (5) In the rare earth flotation operation, the pulp concentration is 40wt%, the flotation temperature is 55°C, the amount of water glass is 2.2kg / t, the amount of hydroxamic acid is 4.2kg / t, and the amount of 2# oil is 0.05kg / t;

[0175] (6) The TFe grade of the obtained iron concentrate is 64.39%, the TFe recovery rate is 91.49%, the F grade is 0.32%, and the F recovery rate is 9.86%. The REO grade of the rare earth flotation concentrate is 67.70%, and the REO recovery rate is 59.43%. The CaF2 grade of the fluorite-rich tailings is 52.65%. The rare earth tailings can be further recovered from fluorite by flotation.

[0176] Example 7

[0177] The system structure is the same as that of Example 1;

[0178] The method is the same as in Example 1, except that:

[0179] (1) TFe 30.45%, REO 4.62%, CaF2 21.54% in the original ore;

[0180] (2) The material temperature in the oxidation decomposer 8 is controlled at 500°C and the residence time is 6 minutes;

[0181] (3) The material temperature in the mineral phase converter 12 is controlled at 500° C. and the residence time is 65 min;

[0182] (4) The volume flow ratio of H2 to CO in the mineral phase converter 12 is 2:1;

[0183] (3) The mineral phase transformation product is ground to -74 μm and the content is 95 wt%; the weak magnetic separation magnetic field strength is 4200 Oe;

[0184] (4) In the reverse flotation defluorination operation, the amount of water glass used is 1.1 kg / t and the amount of sodium oleate is 0.3 kg / t;

[0185] (5) In the rare earth flotation operation, the pulp concentration is 55wt%, the flotation temperature is 65°C, the amount of water glass is 1.6kg / t, the amount of hydroxamic acid is 4.2kg / t, and the amount of 2# oil is 0.05kg / t;

[0186] (6) The TFe grade of the obtained iron concentrate is 65.23%, the TFe recovery rate is 88.71%, the F grade is 0.33%, and the F recovery rate is 9.21%. The REO grade of the rare earth flotation concentrate is 61.55%, and the REO recovery rate is 56.95%. The CaF2 grade of the fluorite-rich tailings is 51.67%. The rare earth tailings can be further recovered from fluorite by flotation.

[0187] Example 8

[0188] The system structure is the same as that of Example 1;

[0189] The method is the same as in Example 1, except that:

[0190] (1) TFe 27.12%, REO 6.22%, CaF2 20.47% in the original ore;

[0191] (2) The material temperature in the oxidation decomposer 8 is controlled at 550°C and the residence time is 5 minutes;

[0192] (3) The material temperature in the mineral phase converter 12 is controlled at 540° C. and the residence time is 55 min;

[0193] (4) The volume flow ratio of H2 to CO in the mineral phase converter 12 is 4:1;

[0194] (3) The mineral phase transformation product is ground to -74 μm and the content is 95 wt%; the weak magnetic separation magnetic field strength is 4000 Oe;

[0195] (4) In the reverse flotation defluorination operation, the amount of water glass used is 1.4 kg / t and the amount of sodium oleate is 0.3 kg / t;

[0196] (5) In the rare earth flotation operation, the pulp concentration is 35wt%, the flotation temperature is 50°C, the amount of water glass is 1.5kg / t, the amount of hydroxamic acid is 4kg / t, and the amount of 2# oil is 0.05kg / t;

[0197] (6) The TFe grade of the obtained iron concentrate is 65.41%, and the TFe recovery rate is 83.98%. The F grade is 0.4%, and the F recovery rate is 8.63%. The REO grade of the rare earth flotation concentrate is 66.68%, and the REO recovery rate is 61.78%. The CaF2 grade of the fluorite-rich tailings is 52.12%. The rare earth tailings can be further recovered from fluorite by flotation.

Claims

1. A system for recovering iron and rare earth from iron-containing rare earth polymetallic ore, characterized in that: The system for recovering iron and rare earth from an iron-containing rare earth polymetallic ore comprises: a feed bin (1), a high pressure roller mill (3), a venturi dryer (5), a first cyclone separator (6), a second cyclone separator (7), an oxidation decomposer (8), a third cyclone separator (10), a first fluidized sealing valve (11), an ore phase converter (12), a second fluidized sealing valve (14), a first cyclone cooler (15), a second cyclone cooler (16), a collecting bin (17), a ball mill (19), a spiral classifier (20), a weak magnetic separator (21), a first defluorination flotation machine (24), a first rare earth flotation machine (25), a second defluorination flotation machine (26) and a second rare earth flotation machine (27); The discharge port of the feed bin (1) is connected to the feed port of the high-pressure roller mill (3), the high-pressure roller mill (3) is connected to the venturi dryer (5), the discharge port of the venturi dryer (5) is connected to the feed port of the first cyclone separator (6), the discharge port of the first cyclone separator (6) is connected to the feed port of the second cyclone separator (7), the discharge port of the second cyclone separator (7) is connected to the feed port of the oxidation decomposer (8), and the oxidation decomposer (8) is connected to the feed port of the oxidation decomposer (8). The discharge port of the third cyclone separator (10) is communicated with the feed port of the third cyclone separator (10) through a pipeline, the discharge port of the third cyclone separator (10) is communicated with the first fluidizing seal valve (11), the discharge port of the first fluidizing seal valve (11) is matched with the mineral phase converter (12), the discharge port of the mineral phase converter (12) is communicated with the second fluidizing seal valve (14), the discharge port of the second fluidizing seal valve (14) is communicated with the feed port of the first cyclone cooler (15), and the first The discharge port of the cyclone cooler (15) is connected to the feed port of the second cyclone cooler (16), the discharge port of the second cyclone cooler (16) is opposite to the collecting bin (17), the collecting bin (17) is connected to the ball mill (19), the discharge port of the ball mill (19) is connected to the feed port of the spiral classifier (20), the overflow port of the spiral classifier (20) is connected to the feed port of the weak magnetic separator (21) through a pipeline, and the concentrate discharge port of the weak magnetic separator (21) is connected to the first degassing device (11). The first defluorination flotation machine (24) is connected to the feed port of the fluorine flotation machine, the bottom discharge port of the first defluorination flotation machine (24) is connected to the second defluorination flotation machine (26); the tailings discharge port of the weak magnetic separator (21) is connected to the feed port of the first rare earth flotation machine (25), the foam product discharge port of the first rare earth flotation machine (25) is connected to the second rare earth flotation machine (27), and the bottom discharge port of the second rare earth flotation machine (27) is connected to the feed port of the first rare earth flotation machine (25) through a pipeline.

2. The system for recovering iron and rare earth from iron-containing rare earth polymetallic ore according to claim 1, characterized in that: The discharge port of the feeding bin (1) is opposite to the feed port of the screw feeder (2), and the discharge port of the screw feeder (2) is opposite to the feed port of the high pressure roller mill (3); and / or, the discharge port of the high pressure roller mill (3) is opposite to the first feeding belt (4), and the discharge end of the first feeding belt (4) is opposite to the feed port of the venturi dryer (5); and / or, the venturi dryer (5) is connected to the drying heat generator (40), and a first ash hopper (38) is provided between the connecting pipes of the venturi dryer (5) and the drying heat generator (40); And / or, a burner (9) is provided at the bottom of the oxidation decomposer (8) and is connected to a reducing gas source and an air source through a pipeline; And / or, the discharge port of the collecting bin (17) is opposite to the second feeding belt (18), and the discharge end of the second feeding belt (18) is opposite to the ball mill (19).

3. The system for recovering iron and rare earth from iron-containing rare earth polymetallic ore according to claim 1, characterized in that: The top of the first cyclone separator (6) is connected to an electrostatic precipitator (32) through a pipeline, the electrostatic precipitator (32) is connected to a tail gas absorption station (33), the tail gas absorption station (33) and an induced draft fan (34) cooperate, and the induced draft fan (34) is connected to a chimney (35) through a pipeline; The discharge port of the electrostatic precipitator (32) is connected to the feed port of the air lift pump (36), the air lift pump (36) is connected to the ash return fan (37), and the discharge port of the air lift pump (36) is connected to the third cyclone separator (10) through a pipeline.

4. The system for recovering iron and rare earth from iron-containing rare earth polymetallic ore according to claim 1, characterized in that: The top discharge port of the second cyclone cooler (16) is connected to the first cyclone cooler (15) through a pipeline, the top discharge port of the first cyclone cooler (15) is connected to the third cyclone separator (10) through a pipeline, the top discharge port of the third cyclone separator (10) is connected to the second cyclone separator (7) through a pipeline, and the top discharge port of the second cyclone separator (7) is connected to the Venturi dryer (5) through a pipeline; In the above system, the discharge port of the first cyclone cooler (15) is connected to the feed port of the second cyclone cooler (16) through a pipeline, and a second ash hopper (39) is also provided on the connecting pipeline.

5. The system for recovering iron and rare earth from iron-containing rare earth polymetallic ore according to claim 1, characterized in that: The mineral phase converter (12) comprises a mineral phase converter shell to form a reduction chamber, a mineral phase conversion feed port and a mineral phase conversion discharge port are arranged on the shell, a plurality of top baffles are arranged at intervals on the inner side of the shell located at the top, a plurality of second bottom baffles are arranged alternately on the inner side of the shell located at the bottom, and a first bottom baffle is arranged directly below the top baffle, a gap is left between the first bottom baffle and the corresponding top baffle, the top baffle and the first bottom baffle and the second bottom baffle together constitute a mineral powder flow channel, and the space formed between the top baffle and the second bottom baffle is a vertical channel; a mineral phase conversion air distribution plate is arranged on the shell on one side of the first bottom baffle and the second bottom baffle to evenly distribute the airflow; a mineral phase conversion air inlet is arranged in each vertical channel to provide loosening air and fluidizing air required for the stable flow of mineral powder.

6. The system for recovering iron and rare earth from iron-containing rare earth polymetallic ore according to claim 1, characterized in that: The first fluidizing sealing valve (11) and the second fluidizing sealing valve (14) have a main body comprising a fluidizing sealing shell, the fluidizing sealing shell forms a fluidizing chamber, a top fluidizing sealing baffle is arranged above the fluidizing chamber, a bottom fluidizing sealing baffle is arranged directly below the top fluidizing sealing baffle, and a fluidizing sealing air distribution plate is arranged on one side of the bottom fluidizing sealing baffle for evenly distributing the airflow; a nitrogen inlet is arranged in each vertical channel for providing loosening air and fluidizing air required for the stable flow of mineral powder.

7. The method for using the system for recovering iron and rare earth from iron-containing rare earth polymetallic ores according to any one of claims 1 to 6, characterized in that: Follow these steps: S1: grinding iron-containing rare earth polymetallic ore with a particle size of less than 50 mm in a high pressure roller mill (3) to a particle size of ≤3 mm to obtain ore powder; S2: introducing combustion flue gas into the Venturi dryer (5) to dry, dehydrate and preheat the mineral powder, wherein the temperature of the preheated mineral powder is 150-200° C.; S3: sending the preheated mineral powder into the first cyclone separator (6) and the second cyclone separator (7) for separation in sequence, and sending the bottom material of the second cyclone separator (7) into the oxidation decomposition device (8); wherein the material entering the oxidation decomposition device (8) meets the particle size requirement of >40 μm; The flue gas is introduced through the air inlet at the bottom of the oxidation decomposer (8), so that the material in the oxidation decomposer (8) is oxidized and decomposed and placed in a suspended state, and the oxidation decomposition is performed at a temperature of 450 to 750° C. and a residence time of 2 to 10 minutes, thereby obtaining suspended oxidation decomposed ore powder; S4: After the suspended oxidative decomposition of the mineral powder is subjected to cyclone separation, the bottom material is sealed in the first fluidized sealing valve (11) to isolate the air and oxygen, and then mixed with the reducing gas and introduced into the mineral phase converter (12) for mineral phase conversion to obtain the converted mineral powder; In the process of mineral phase conversion, the temperature is controlled at 430-550°C and the residence time is 20-90 minutes; the introduced reducing gas is one or a mixed reducing gas composed of H2, CO, methane, natural gas and coal-based gas; if the mixed reducing gas contains H2, the volume ratio of H2 in the mixed reducing gas is ≥55%; S5: The converted mineral powder is sealed and isolated from the reducing gas by the second fluidized sealing valve (14), and then is cooled to 150-200° C. by heat exchange through the first cyclone cooler (15) and the second cyclone cooler (16), thereby obtaining cooled mineral powder; S6: After the cooled ore powder is ball-milled in a ball mill (19), it is discharged into a spiral classifier (20) and classified according to the different specific gravities of the ore powder, wherein the mass percentage of the ore powder with a particle size of -74 μm accounts for 80 to 96 wt %. The ore powder is discharged into a weak magnetic separator (21) for weak magnetic separation, and the magnetic field strength is 2300 to 4500 Oe to obtain magnetically separated iron ore concentrate and magnetically separated tailings; S7： (1) magnetically selected iron concentrate is used as a flotation mineral, slurried and an iron flotation agent is added, and defluorination reverse flotation roughing is performed in a first defluorination flotation machine (24), the reverse flotation roughing temperature is controlled at 20 to 40° C., and the mass concentration of the magnetically selected iron concentrate slurry is controlled at 30 to 40 wt %, to obtain reverse flotation tailings and reverse flotation concentrate; The reverse flotation concentrate enters the second defluorination flotation machine (26) for defluorination reverse flotation concentration to obtain iron concentrate; (2) the magnetic tailings are used as flotation minerals, slurried and added with rare earth flotation reagents to be discharged into a first rare earth flotation machine (25) for rare earth direct flotation roughing, the direct flotation temperature is controlled at 40-70° C., and the magnetic tailings slurry concentration is controlled at 35-55wt%, to obtain roughing concentrate and roughing tailings; The rougher concentrate is introduced into a second rare earth flotation machine (27) for rare earth positive flotation separation to obtain a rare earth concentrate.

8. The method for using the system for recovering iron and rare earth from iron-containing rare earth polymetallic ores according to claim 7, characterized in that: In the above-mentioned S3, the flue gas is formed by a mixed gas of air and reducing gas introduced into the burner (9); the preheated mineral powder is separated from the waste gas and dust by the first cyclone separator (6), wherein the waste gas is discharged after purification, and the dust is collected by the electrostatic precipitator (32); The flue gas generated during the operation of the oxidation decomposer (8) used for oxidation decomposition is returned to the Venturi dryer (5) through a pipeline via the third cyclone separator (10) and the second cyclone separator (7) to realize waste heat utilization.

9. The method for using the system for recovering iron and rare earth from iron-containing rare earth polymetallic ores according to claim 7, characterized in that: In the above-mentioned S4, the excess reducing gas in the mineral phase converter (12) carries part of the mineral powder through the fourth cyclone separator (13) for classification, and the fine-grained dust returns to the oxidation decomposer (8) with the reducing gas to continue to participate in the circulation, and the coarse-grained mineral powder returns to the mineral phase converter (12) to enter the next step.

10. The method for using the system for recovering iron and rare earth from iron-containing rare earth polymetallic ores according to claim 7, characterized in that: In the above method, in S7, the reverse flotation reagents used in the defluorination reverse flotation roughing include a reverse flotation inhibitor and a reverse flotation collector, the reverse flotation inhibitor is water glass, the amount of which is 0.5-1.5 kg / t, and the reverse flotation collector is sodium oleate, the amount of which is 0.04-1.2 kg / t; And / or, the positive flotation reagents used in the roughing of the rare earth positive flotation include a positive flotation inhibitor, a positive flotation collector and a frother, the positive flotation inhibitor is water glass, the dosage is 0.1-4 kg / t, the positive flotation collector is hydroxamic acid, the dosage is 0.15-5.5 kg / t, and the frother is 2# oil, the dosage is 0.01-0.1 kg / t.

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