Fluidized roasting-leaching method for mixed rare earth concentrate

Abstract

The invention discloses a fluidized roasting-leaching method of mixed rare earth concentrate, which comprises the following steps: carrying out fluidized roasting on the mixed rare earth concentrate under inert gas to convert bastnaesite phase in the mixed rare earth concentrate into cerium fluoride to obtain a roasted product; performing primary mechanical activation treatment on the roasted product to obtain a primary activated product; carrying out acid leaching reaction on the primary activation product to obtain an acid leaching product; the acid leaching product comprises an acid leaching solution containing rare earth and fluorine elements and leaching residues containing monazite; carrying out secondary mechanical activation treatment on the leaching residue containing monazite to obtain a secondary activated product; carrying out alkaline leaching treatment on the secondary activation product to obtain an alkaline leaching product; the alkaline leaching product comprises a leaching solution containing phosphorus and leaching residues containing rare earth elements. According to the method, rare earth elements, phosphorus elements and fluorine elements in the mixed rare earth concentrate can be effectively separated, so that the resource comprehensive utilization rate of the mixed rare earth concentrate is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of rare earth ore dressing, and in particular relates to a fluidized roasting-leaching method for mixed rare earth concentrate. Background Art

[0002] The Bayan Obo mixed rare earth mine is the world's largest single rare earth deposit, with its industrial rare earth reserves accounting for about 84% of China's industrial reserves and 38% of the world's industrial reserves. It is mainly a mixed ore of fluorocarbon cerium ore and monazite. The main associated minerals are fluorite, iron minerals, apatite, etc. It has a complex mineral composition, many ore types, fine embedded grains, and close mineral symbiosis. It is recognized by the world as a difficult-to-smelt mineral.

[0003] The further smelting process of rare earth mixed concentrate mainly includes concentrated sulfuric acid roasting method, caustic soda decomposition method, and oxidative roasting-hydrochloric acid leaching method. At present, 90% of rare earth mixed concentrates in industry are smelted by concentrated sulfuric acid roasting method. However, concentrated sulfuric acid is easily decomposed and wasted during the high-temperature roasting process of this process, and fluorine-containing and sulfur-containing tail gas will be produced. Ammonia nitrogen wastewater will also be produced during the leaching process. In addition, valuable elements such as phosphorus and thorium enter the waste slag in the form of insoluble phosphates and accumulate in large quantities, resulting in waste of resources and excessive radioactivity. The caustic soda decomposition method has high requirements on the grade of rare earth concentrate and requires a pre-impurity removal process, which leads to discontinuous process and is not easy for large-scale production. These reasons restrict the application of the caustic soda decomposition method in industry. In the oxidative roasting-hydrochloric acid leaching method, Ce is easily oxidized to tetravalent during the oxidative roasting process, which is difficult to leach and will also convert Cl into tetravalent in the concentrated hydrochloric acid environment. - Oxidation to Cl2 causes pollution.

[0004] Therefore, conducting cutting-edge technological research on the Bayan Obo rare earth mixed concentrate and constructing an efficient extraction system for the rare earth mixed concentrate can provide a research basis for exploring the green, comprehensive and efficient smelting process of the Bayan Obo mixed rare earth concentrate, which is of great significance to promoting the sustainable development of the rare earth industry. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a fluidized roasting-leaching method for a mixed rare earth concentrate.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: The present invention provides a fluidized roasting-leaching method for a mixed rare earth concentrate, comprising: Fluidized roasting of the mixed rare earth concentrate under inert gas to convert the bastnaesite phase in the mixed rare earth concentrate into cerium fluoride oxide to obtain a roasting product; Performing a mechanical activation treatment on the calcined product to obtain a primary activated product; The primary activated product is subjected to an acid leaching reaction to obtain an acid leaching product; the acid leaching product includes an acid leaching solution containing rare earth and fluorine elements, and a leaching residue containing monazite; The monazite-containing leaching residue is subjected to secondary mechanical activation treatment to obtain a secondary activation product; The secondary activation product is subjected to alkaline leaching treatment to obtain an alkaline leaching product; the alkaline leaching product includes a leaching solution containing phosphorus elements and a leaching residue containing rare earth elements.

[0007] Optionally, the mixed rare earth concentrate is subjected to fluidized roasting under an inert gas to convert the bastnaesite phase in the mixed rare earth concentrate into cerium oxyfluoride to obtain a roasting product, comprising: The mixed rare earth concentrate is fluidized roasted in an inert gas atmosphere at a temperature of 500 to 800°C for 20 to 120 minutes to obtain a roasted product; wherein the gas flow rate of the inert gas is 300 to 1000 mL / min; The calcined product is cooled to room temperature under the protection of an inert gas to obtain a final calcined product.

[0008] Optionally, the particle size of the primary activation product accounting for more than 99% of the total weight is 350-450 mesh; correspondingly, the particle size of the secondary activation product accounting for more than 99% of the total weight is 350-450 mesh.

[0009] Optionally, subjecting the primary activation product to an acid leaching reaction to obtain an acid leaching product comprises: Adding an acidic leaching solution to the primary activation product, stirring the mixture at a temperature of 60 to 100° C. and a stirring speed of 200 to 600 r / min for 20 to 120 min to obtain a hydrochloric acid leaching mixture; The hydrochloric acid leaching mixture is filtered and washed in sequence to obtain an acidic leaching solution containing rare earth and fluorine elements and a leaching residue containing monazite.

[0010] Optionally, the liquid-solid ratio of the acidic leaching solution and the primary activation product is 6 to 20:1; the acidic leaching solution includes a first hydrochloric acid solution with a concentration of 2 to 8 mol / L and a complexing agent solution with a concentration of 0.1 to 0.6 mol / L.

[0011] Optionally, the complexing agent is one or more of AlCl3, boric acid and borate.

[0012] Optionally, the secondary activation product is subjected to alkaline leaching treatment to obtain an alkaline leaching product, comprising: adding an alkaline leaching solution to the secondary activation product, and stirring the mixture at a temperature of 160 to 200° C. and a stirring speed of 300 to 600 r / min for 100 to 160 min to obtain an alkaline leaching mixture; The alkaline leaching mixture is filtered and washed in sequence to obtain a leaching solution containing phosphorus elements and a leaching residue containing rare earth elements.

[0013] Optionally, the liquid-solid ratio of the alkaline leaching solution and the secondary activation product is 3 to 5:1; the alkaline leaching solution is a sodium hydroxide sub-molten salt prepared with a sodium hydroxide solution with a mass fraction of 40% to 80%.

[0014] Optionally, it also includes: A second hydrochloric acid solution having a temperature of 50 to 70° C. is added to the leached residue containing the rare earth elements, so that the second hydrochloric acid solution dissolves the leached residue containing the rare earth elements to obtain an acidic solution containing the rare earth elements.

[0015] Optionally, the liquid-to-solid ratio of the second hydrochloric acid solution to the leached residue containing rare earth elements is 8 to 12:1; and the concentration of the second hydrochloric acid solution is 1.5 to 2.5 mol / L.

[0016] The present invention provides a fluidized roasting-leaching method for a mixed rare earth concentrate, which comprises the following steps: fluidizing roasting the mixed rare earth concentrate under an inert gas to convert the bastnaesite phase in the mixed rare earth concentrate into cerium fluoride oxide that is easily leached by acid; performing a mechanical activation treatment on the roasted product to make the obtained primary activation product have a high reaction activity; then, performing an acid leaching reaction on the primary activation product to obtain an acid leaching product including an acid leaching solution containing rare earth elements and fluorine elements and a leaching residue containing monazite, thereby completing a primary leaching reaction between monazite and part of the rare earth elements and fluorine elements in the mixed rare earth concentrate. separation; then subjecting the leaching residue containing monazite to secondary mechanical activation treatment to obtain a secondary activation product with higher reaction activity; finally, subjecting the secondary activation product to alkaline leaching treatment to obtain an alkaline leaching product including a leaching solution containing phosphorus and leaching residue containing rare earth elements, thereby completing the separation of another part of the rare earth elements in the mixed rare earth concentrate from the phosphorus element; it can be seen that the present invention can effectively separate the rare earth elements, phosphorus elements and fluorine elements in the mixed rare earth concentrate, realize the comprehensive recovery of resources such as fluorite and apatite associated with the mixed rare earth concentrate, and improve the comprehensive utilization rate of resources of the mixed rare earth concentrate.

[0017] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0018] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The present invention is a flow chart of a fluidized roasting-leaching method for a mixed rare earth concentrate according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0021] The present invention provides a fluidized roasting-leaching method for a mixed rare earth concentrate, comprising the following steps: Step 1, fluidizing and roasting the mixed rare earth concentrate under an inert gas to convert the bastnaesite phase in the mixed rare earth concentrate into cerium oxyfluoride to obtain a roasting product; Step 2, performing a mechanical activation treatment on the calcined product to obtain a primary activated product; Step 3, subjecting the primary activated product to an acidic leaching reaction to obtain an acidic leaching product; the acidic leaching product includes an acidic leaching solution containing rare earth elements and fluorine elements, and a leaching residue containing monazite; Step 4, subjecting the monazite-containing leaching residue to secondary mechanical activation treatment to obtain a secondary activation product; Step 5: performing alkaline leaching treatment on the secondary activation product to obtain an alkaline leaching product; the alkaline leaching product includes a leaching solution containing phosphorus elements and a leaching residue containing rare earth elements.

[0022] It should be noted that the mixed rare earth concentrate can be the Bayan Obo mixed rare earth ore, the REO grade of the mixed rare earth concentrate is 50% to 67%, and the main rare earth minerals included are fluorocarbon cerium ore and monazite; the F grade of the mixed rare earth concentrate is 4% to 10%, and the main fluorine-containing minerals included are fluorocarbon cerium ore, fluorite, and apatite; the P grade of the mixed rare earth concentrate is 4% to 10%, and the main phosphorus-containing minerals included are monazite and apatite.

[0023] Here, by fluidizing and roasting the mixed rare earth concentrate under inert gas in step 1, bastnaesite can be quickly phase-converted into cerium oxyfluoride which is more easily subjected to acid leaching reaction, and then after the roasted product containing cerium oxyfluoride completes the acid leaching reaction, the acidic leaching solution containing rare earth and fluorine elements contains cerium rare earth elements and non-cerium rare earth elements in the mixed rare earth concentrate that can be leached by acid.

[0024] In step 2, by subjecting the roasted product to a mechanical activation treatment, mineral dissociation and structural fracture of the roasted product can occur, thereby improving the reaction activity of the roasted product, so that the roasted product after the mechanical activation treatment can smoothly undergo an acid leaching reaction, and the acid leaching product obtained in step 3 includes an acidic leaching solution containing rare earth elements and fluorine elements, and a leaching residue containing monazite, wherein the rare earth elements in the acidic leaching solution here can include trivalent cerium ions in the cerium oxyfluoride phase-transformed from fluorocarbon cerium ore in step 1, and trivalent cerium ions in fluorocarbon cerium ore that has not been phase-transformed. Similarly, in step 4, by subjecting the leaching residue containing monazite to secondary mechanical activation treatment, mineral dissociation and structural fracture of the leaching residue containing monazite can be caused, thereby improving the reaction activity of the leaching residue, so that the leaching residue after the secondary mechanical activation treatment can smoothly undergo an alkaline leaching reaction, and the alkaline leaching product obtained in step 5 includes a leachate containing phosphorus elements and leaching residue containing rare earth elements, wherein the leaching residue containing rare earth elements here does not contain or contains a small amount of tetravalent cerium ions.

[0025] In this embodiment, the mixed rare earth concentrate is subjected to fluidized roasting under an inert gas to convert the fluorocarbon cerium ore phase in the mixed rare earth concentrate into cerium oxyfluoride that is easily leached by acid; the roasted product is subjected to a mechanical activation treatment to make the obtained primary activation product have a higher reaction activity; then, the primary activation product is subjected to an acid leaching reaction to obtain an acid leaching product including an acid leaching solution containing rare earth elements and fluorine elements, and a leaching residue containing monazite, thereby completing a primary separation of monazite and part of the rare earth elements and fluorine elements in the mixed rare earth concentrate; the leaching residue containing monazite is subjected to a secondary mechanical activation treatment to obtain an acid leaching product having a higher reaction activity. secondary activation product; finally, the secondary activation product is subjected to alkaline leaching treatment to obtain an alkaline leaching product including a leaching solution containing phosphorus and a leaching residue containing rare earth elements, thereby completing the separation of another part of the rare earth elements in the mixed rare earth concentrate and the phosphorus element; thus, the present invention can effectively separate the rare earth elements, phosphorus elements and fluorine elements in the mixed rare earth concentrate, realize the comprehensive recovery of fluorite, apatite and other resources associated with the mixed rare earth concentrate, improve the comprehensive utilization rate of resources of the mixed rare earth concentrate, provide a research basis for exploring an efficient, comprehensive and green Bayan Obo mixed rare earth ore smelting process, and is of great significance to the green and sustainable development of the rare earth industry.

[0026] In some possible embodiments, the mixed rare earth concentrate in step 1 is subjected to fluidized roasting under an inert gas to convert the bastnaesite phase in the mixed rare earth concentrate into cerium oxyfluoride to obtain a roasting product, comprising the following steps: Step 101, fluidizing and roasting the mixed rare earth concentrate in an inert gas atmosphere at a temperature of 500 to 800° C. for 20 to 120 min to obtain a roasted product; wherein the gas flow rate of the inert gas is 300 to 1000 mL / min; Step 102: Cool the calcined product to room temperature under the protection of an inert gas to obtain a final calcined product.

[0027] Here, in step 101, after the mixed rare earth concentrate is added into a vertical tube furnace at a temperature of 500 to 800° C., an inert gas with a gas flow rate of 300 to 1000 mL / min is introduced from the bottom of the vertical tube furnace, and the inert gas is used as the fluidizing gas for the fluidized roasting to keep the mixed rare earth concentrate in a fluidized state. The inert gas may be nitrogen, argon, and helium.

[0028] In this embodiment, by fluidizing the mixed rare earth concentrate for roasting in an inert gas atmosphere and cooling the roasted product under the protection of an inert gas, the oxidation reaction between the fluorocarbon cerium ore in the mixed rare earth concentrate and the oxygen in the air can be avoided. Without generating fluorine-containing tail gas and CeO2, the fluorocarbon cerium ore (REFCO3) in the mixed rare earth concentrate can be directionally converted into cerium oxyfluoride (REOF) which is more easily acid leached. Furthermore, due to its stability, the monazite in the mixed rare earth concentrate does not undergo a phase change in this step. Therefore, through this embodiment, the fluorocarbon cerium ore in the mixed rare earth concentrate can be converted into cerium oxyfluoride, which facilitates the leaching and separation of cerium oxyfluoride and monazite in the mineral phase conversion product in the subsequent steps.

[0029] In some possible embodiments, the particle size of the primary activation product accounting for more than 99% of the total weight is 350-450 mesh; correspondingly, the particle size of the secondary activation product accounting for more than 99% of the total weight is 350-450 mesh.

[0030] Here, the calcined product and the leaching residue containing monazite are respectively ball-milled by a planetary ball mill, so that the calcined product and the leaching residue containing monazite undergo mineral dissociation and structural fracture through the action of mechanical force, thereby increasing the corresponding reaction activities of the primary activation product and the secondary activation product obtained; wherein, the ball-milling time of the calcined product and the leaching residue containing monazite by the planetary ball mill is 1 to 24 h.

[0031] It should be noted that before the planetary ball mill is used to ball-mill the monazite-containing leaching residue, the method further includes: drying the washed monazite-containing leaching residue in an oven at 80-120°C.

[0032] In this embodiment, by making the particle size of the primary activation product and the secondary activation product, which accounts for more than 99% of the total weight, 350-450 mesh, the primary activation product and the secondary activation product can undergo mineral dissociation and structural fracture under the action of mechanical force, thereby improving the reaction activity of the primary activation product and the secondary activation product and enhancing the leaching effect of the primary activation product and the secondary activation product.

[0033] In some possible embodiments, the acid leaching reaction of the primary activation product in step 3 to obtain the acid leaching product comprises the following steps: Step 301, adding an acidic leaching solution to the primary activation product, and stirring the mixture at a temperature of 60 to 100° C. and a stirring speed of 200 to 600 r / min for 20 to 120 min to obtain a hydrochloric acid leaching mixture; Step 302: filtering and washing the hydrochloric acid leaching mixture in sequence to obtain an acidic leaching solution containing rare earth elements and fluorine elements, and a leaching residue containing monazite.

[0034] Since the roasted product obtained in step 1 contains cerium oxyfluoride converted from the fluorocarbon cerium ore phase, the cerium oxyfluoride is leached by the acidic leaching solution to generate an acidic leaching solution containing cerium rare earth elements, and the monazite in the mixed rare earth concentrate is insoluble in the acidic leaching solution, therefore, by adding the acidic leaching solution to the primary activation product after the mechanical activation treatment of the roasted product, the obtained acidic leaching solution can contain cerium rare earth elements, non-cerium rare earth elements and fluorine elements that can be leached by the acidic leaching solution, and the obtained leaching residue contains monazite, so as to achieve effective separation between monazite and cerium rare earth elements that can be leached by acid, non-cerium rare earth elements and fluorine elements that can be leached by the acidic leaching solution.

[0035] Furthermore, the liquid-solid ratio of the acidic leaching solution and the primary activation product is 6-20:1; the acidic leaching solution includes a first hydrochloric acid solution with a concentration of 2-8 mol / L and a complexing agent solution with a concentration of 0.1-0.6 mol / L.

[0036] Here, by using the first hydrochloric acid solution and the chelating agent as important components of the acidic leaching solution, the fluoride ions in the primary activation product can be chelated by the chelating agent solution, which can reduce the generation of REF3, increase the leaching rate of rare earth elements, and dissolve the associated fluorite, thereby improving the utilization rate of resources and realizing the comprehensive utilization of resources.

[0037] Furthermore, the complexing agent is one or more of AlCl3, boric acid and borate.

[0038] Here, in order to prevent new impurity ions from being introduced into the primary activation product, the complexing agent is selected from one or more of AlCl3, boric acid and borate, so that the complexing agent can complex the fluoride ions in the primary activation product, reduce the generation of REF3, and improve the leaching rate of rare earth elements.

[0039] In some possible embodiments, the alkaline leaching treatment of the secondary activation product in step 5 to obtain an alkaline leaching product comprises the following steps: Step 501, adding an alkaline leaching solution to the secondary activation product, and stirring the mixture at a temperature of 160 to 200° C. and a stirring speed of 300 to 600 r / min for 100 to 160 min to obtain an alkaline leaching mixture; Step 502: filtering and washing the alkaline leaching mixture in sequence to obtain a leaching solution containing phosphorus and a leaching residue containing rare earth elements.

[0040] In this embodiment, by adding alkaline leaching solution to the secondary activation product, the secondary activation product can be leached by the alkaline leaching solution to obtain a leaching solution containing phosphorus and a leaching residue containing rare earth elements, thereby realizing the leaching separation of phosphorus and rare earth elements.

[0041] Furthermore, the liquid-solid ratio of the alkaline leaching solution and the secondary activation product is 3 to 5:1; the alkaline leaching solution is a sodium hydroxide sub-molten salt prepared with a sodium hydroxide solution with a mass fraction of 40% to 80%.

[0042] Here, by selecting the alkaline leachate as a sodium hydroxide sub-molten salt prepared by a sodium hydroxide solution with a mass fraction of 40% to 80%, the enhanced leaching of the secondary activation product by the sodium hydroxide solution can be achieved, and the leaching effect of the secondary activation product can be improved; it can be seen that this embodiment can utilize the characteristics of high reaction activity, high boiling point and low vapor pressure of the sodium hydroxide sub-molten salt to enhance the leaching of the secondary activation product, improve the leaching effect, and the high concentration of sodium hydroxide solution is also easy to recover, thereby reducing the waste of resources and the discharge of wastewater.

[0043] In some possible embodiments, in step 5, the secondary activation product is subjected to alkaline leaching treatment to obtain an alkaline leaching product; after the alkaline leaching product includes a leaching solution containing phosphorus elements and a leaching residue containing rare earth elements, it may also include: adding a second hydrochloric acid solution with a temperature of 50 to 70 ° C to the leaching residue containing rare earth elements, so that the second hydrochloric acid solution dissolves the leaching residue containing rare earth elements to obtain an acidic solution containing rare earth elements.

[0044] Here, before adding the second hydrochloric acid solution to the leaching residue containing rare earth elements, the method further includes filtering the alkaline leaching product and washing the filtered alkaline leaching product 3 to 5 times with hot water at a temperature of 60 to 100° C. to obtain a final phosphorus-containing leaching solution and a leaching residue containing rare earth elements; wherein the phosphorus-containing leaching solution can be recovered after treatment.

[0045] It should be noted that, since the leaching residue containing rare earth elements is obtained by alkaline leaching treatment of the secondary activation product, the surface of the leaching residue containing rare earth elements is easily attached to the alkaline solution. At the same time, the leaching residue containing rare earth elements here is easily soluble in hydrochloric acid. Therefore, by adding the second hydrochloric acid solution with a temperature of 50 to 70 ° C to the leaching residue containing rare earth elements, not only can the second hydrochloric acid solution dissolve the leaching residue containing rare earth elements, but also the alkaline solution attached to the surface of the leaching residue containing rare earth elements can react with the second hydrochloric acid solution to obtain an acidic solution containing rare earth elements that is convenient for recovering the rare earth elements.

[0046] In this embodiment, by adding a second hydrochloric acid solution with a temperature of 50 to 70° C. to the leached residue containing rare earth elements, the second hydrochloric acid solution is used to dissolve the leached residue containing rare earth elements, so that the rare earth elements in the leached residue are dissolved in the second hydrochloric acid solution, and an acidic solution containing rare earth elements is obtained for facilitating the recovery of the rare earth elements; thus, it can be seen that the leached residue containing rare earth elements in the alkaline leaching product obtained by subjecting the secondary activation product to alkaline leaching treatment can be treated with the second hydrochloric acid solution to obtain an acidic solution containing rare earth elements, which can facilitate the recovery of rare earth elements in the leached residue containing rare earth elements and reduce the waste of resources and the discharge of wastewater in the recovery process of rare earth elements.

[0047] Furthermore, the liquid-to-solid ratio of the second hydrochloric acid solution to the leaching residue containing rare earth elements is 8-12:1; and the concentration of the second hydrochloric acid solution is 1.5-2.5 mol / L.

[0048] Here, by selecting the liquid-to-solid ratio of the second hydrochloric acid solution and the leaching residue containing rare earth elements to be 8 to 12:1, and the concentration of the second hydrochloric acid solution to be 1.5 to 2.5 mol / L, the acidic dissolution of the leaching residue containing rare earth elements by the second hydrochloric acid solution can be achieved, thereby improving the dissolution effect of the leaching residue containing rare earth elements.

[0049] The fluidized roasting-leaching method of a mixed rare earth concentrate provided by the present invention is specifically described below by way of examples. It should be noted that the methods, reagents and materials described in the following examples, unless otherwise specified, can all be obtained from commercial channels; the test methods, unless otherwise specified, are all conventional methods.

[0050] Example 1 The present embodiment provides a fluidized roasting-leaching method for a mixed rare earth concentrate, comprising the following steps: (1) A mixed rare earth concentrate with a REO grade of 59.24%, a F grade of 6.21%, and a P grade of 5.54% was added into a vertical tube furnace at 650°C, and 400 mL / min of nitrogen was introduced from the bottom of the vertical tube furnace, so that the mixed rare earth concentrate was fluidized and roasted for 65 min in an environment of nitrogen as a fluidizing gas to obtain a roasted product; (2) cooling the calcined product to room temperature under the protection of nitrogen to obtain a final calcined product; (3) ball milling the calcined product for 1 hour to complete a primary mechanical activation treatment of the calcined product, and obtaining a primary activated product with a particle size of 400 mesh accounting for more than 99% of the total weight; (4) adding an acidic leaching solution to the primary activation product so that the liquid-to-solid ratio of the acidic leaching solution to the primary activation product is 12:1, and stirring the mixture at a temperature of 60° C. and a stirring speed of 600 r / min for 20 min to obtain a hydrochloric acid leaching mixture including an acidic leaching solution containing rare earth and fluorine elements and a leaching residue containing monazite; wherein the acidic leaching solution includes a first hydrochloric acid solution with a concentration of 3 mol / L and an AlCl3 solution with a concentration of 0.4 mol / L; (5) filtering the hydrochloric acid leaching mixture in sequence, and then washing it with hot water at 60° C. to obtain an acidic leaching solution containing rare earth and fluorine elements, and a leaching residue containing monazite; (6) drying the washed monazite-containing leaching residue in an oven at 80° C., and then ball milling it in a ball mill for 1 h to complete a secondary mechanical activation treatment of the monazite-containing leaching residue, thereby obtaining a secondary activation product with a particle size of 400 mesh accounting for more than 99% of the total weight; (7) adding sodium hydroxide sub-molten salt prepared by sodium hydroxide solution with a mass fraction of 70% as an alkaline leaching solution to the secondary activation product, so that the liquid-to-solid ratio of the alkaline leaching solution to the secondary activation product is 5:1, and stirring the mixture at a temperature of 180°C and a stirring speed of 400 r / min for 120 min to obtain an alkaline leaching mixture of a leaching solution containing phosphorus elements and a leaching residue containing rare earth elements; wherein the leaching solution containing phosphorus elements can be treated to recover the alkaline solution; (8) filtering the alkaline leaching mixture in sequence, and then washing it with hot water at 60°C to obtain a leaching solution containing phosphorus elements and a leaching residue containing rare earth elements; (9) adding a second hydrochloric acid solution having a temperature of 60°C and a concentration of 2 mol / L to the leached residue containing rare earth elements, so that the liquid-to-solid ratio of the second hydrochloric acid solution to the leached residue containing rare earth elements is 10:1, so that the second hydrochloric acid solution dissolves the leached residue containing rare earth elements to obtain an acidic solution containing rare earth elements.

[0051] In this embodiment, the total leaching rate of the rare earth element-containing leaching solution (the rare earth element-containing leaching solution includes the rare earth element-containing acidic leaching solution in step (5) and the rare earth element-containing acidic solution in step (9)) is 95.30%, wherein the leaching rate of fluorine in the fluorine element acidic leaching solution in step (5) is 94.71%, and the leaching rate of phosphorus in the phosphorus element-containing leaching solution in step (8) is 96.58%.

[0052] Example 2 The present embodiment provides a fluidized roasting-leaching method for a mixed rare earth concentrate, comprising the following steps: (1) A mixed rare earth concentrate with a REO grade of 59.24%, a F grade of 6.21%, and a P grade of 5.54% was added into a vertical tube furnace at 700°C, and 400 mL / min of nitrogen was introduced from the bottom of the vertical tube furnace, so that the mixed rare earth concentrate was fluidized and roasted for 65 min in an environment of nitrogen as a fluidizing gas to obtain a roasted product; (2) cooling the calcined product to room temperature under the protection of nitrogen to obtain a final calcined product; (3) ball milling the calcined product for 1 hour to complete a primary mechanical activation treatment of the calcined product, and obtain a primary activated product with a particle size of 400 mesh accounting for more than 99% of the total weight; (4) adding an acidic leaching solution to the primary activation product so that the liquid-to-solid ratio of the acidic leaching solution to the primary activation product is 12:1, and stirring the mixture at a temperature of 60° C. and a stirring speed of 600 r / min for 20 min to obtain a hydrochloric acid leaching mixture including an acidic leaching solution containing rare earth and fluorine elements and a leaching residue containing monazite; wherein the acidic leaching solution includes a first hydrochloric acid solution with a concentration of 3 mol / L and an AlCl3 solution with a concentration of 0.4 mol / L; (5) filtering the hydrochloric acid leaching mixture in sequence, and then washing it with hot water at 60° C. to obtain an acidic leaching solution containing rare earth and fluorine elements, and a leaching residue containing monazite; (6) drying the washed monazite-containing leaching residue in an oven at 80° C., and then ball milling the monazite-containing leaching residue in a ball mill for 1 h to complete secondary mechanical activation treatment of the monazite-containing leaching residue, thereby obtaining a secondary activation product with a particle size of 400 mesh accounting for more than 99% of the total weight; (7) adding sodium hydroxide sub-molten salt prepared by sodium hydroxide solution with a mass fraction of 70% as an alkaline leaching solution to the secondary activation product, so that the liquid-to-solid ratio of the alkaline leaching solution to the secondary activation product is 5:1, and stirring the mixture at a temperature of 180°C and a stirring speed of 400 r / min for 120 min to obtain an alkaline leaching mixture of a leaching solution containing phosphorus elements and a leaching residue containing rare earth elements; wherein the leaching solution containing phosphorus elements can be treated to recover the alkaline solution; (8) filtering the alkaline leaching mixture in sequence, and then washing it with hot water at 60°C to obtain a leaching solution containing phosphorus elements and a leaching residue containing rare earth elements; (9) adding a second hydrochloric acid solution having a temperature of 60°C and a concentration of 2 mol / L to the leached residue containing rare earth elements, so that the liquid-to-solid ratio of the second hydrochloric acid solution to the leached residue containing rare earth elements is 10:1, so that the second hydrochloric acid solution dissolves the leached residue containing rare earth elements to obtain an acidic solution containing rare earth elements.

[0053] In this embodiment, the total leaching rate of the rare earth element-containing leaching solution (the rare earth element-containing leaching solution includes the rare earth element-containing acidic leaching solution in step (5) and the rare earth element-containing acidic solution in step (9)) is 96.13%, wherein the leaching rate of fluorine in the fluorine element acidic leaching solution in step (5) is 95.63%, and the leaching rate of phosphorus in the phosphorus element-containing leaching solution in step (8) is 95.76%.

[0054] Example 3 The present embodiment provides a fluidized roasting-leaching method for a mixed rare earth concentrate, comprising the following steps: (1) A mixed rare earth concentrate with a REO grade of 59.24%, a F grade of 6.21%, and a P grade of 5.54% was added into a vertical tube furnace at 700°C, and 400 mL / min of nitrogen was introduced from the bottom of the vertical tube furnace, so that the mixed rare earth concentrate was fluidized and roasted for 65 min in an environment of nitrogen as a fluidizing gas to obtain a roasted product; (2) cooling the calcined product to room temperature under the protection of nitrogen to obtain a final calcined product; (3) ball milling the calcined product for 1 hour to complete a primary mechanical activation treatment of the calcined product, and obtaining a primary activated product with a particle size of 400 mesh accounting for more than 99% of the total weight; (4) adding an acidic leaching solution to the primary activation product so that the liquid-to-solid ratio of the acidic leaching solution to the primary activation product is 12:1, and stirring the mixture at a temperature of 75° C. and a stirring speed of 600 r / min for 20 min to obtain a hydrochloric acid leaching mixture including an acidic leaching solution containing rare earth and fluorine elements and a leaching residue containing monazite; wherein the acidic leaching solution includes a first hydrochloric acid solution with a concentration of 3 mol / L and an AlCl3 solution with a concentration of 0.4 mol / L; (5) filtering the hydrochloric acid leaching mixture in sequence, and then washing it with hot water at 75° C. to obtain an acidic leaching solution containing rare earth and fluorine elements, and a leaching residue containing monazite; (6) drying the washed monazite-containing leaching residue in an oven at 80° C., and then ball milling the monazite-containing leaching residue in a ball mill for 1 h to complete secondary mechanical activation treatment of the monazite-containing leaching residue, thereby obtaining a secondary activation product with a particle size of 400 mesh accounting for more than 99% of the total weight; (7) adding sodium hydroxide sub-molten salt prepared by sodium hydroxide solution with a mass fraction of 70% as an alkaline leaching solution to the secondary activation product, so that the liquid-to-solid ratio of the alkaline leaching solution to the secondary activation product is 5:1, and stirring the mixture at a temperature of 180°C and a stirring speed of 400 r / min for 120 min to obtain an alkaline leaching mixture of a leaching solution containing phosphorus elements and a leaching residue containing rare earth elements; wherein the leaching solution containing phosphorus elements can be treated to recover the alkaline solution; (8) filtering the alkaline leaching mixture in sequence, and washing it with hot water at 75°C to obtain a leaching solution containing phosphorus elements and a leaching residue containing rare earth elements; (9) adding a second hydrochloric acid solution having a temperature of 60°C and a concentration of 2 mol / L to the leached residue containing rare earth elements, so that the liquid-to-solid ratio of the second hydrochloric acid solution to the leached residue containing rare earth elements is 10:1, so that the second hydrochloric acid solution dissolves the leached residue containing rare earth elements to obtain an acidic solution containing rare earth elements.

[0055] In this embodiment, the total leaching rate of the rare earth element-containing leaching solution (the rare earth element-containing leaching solution includes the rare earth element-containing acidic leaching solution in step (5) and the rare earth element-containing acidic solution in step (9)) is 98.68%, wherein the leaching rate of fluorine in the fluorine element acidic leaching solution in step (5) is 98.82%, and the leaching rate of phosphorus in the phosphorus element-containing leaching solution in step (8) is 96.39%.

[0056] Example 4 The present embodiment provides a fluidized roasting-leaching method for a mixed rare earth concentrate, comprising the following steps: (1) A mixed rare earth concentrate with a REO grade of 59.24%, a F grade of 6.21%, and a P grade of 5.54% was added into a vertical tube furnace at 700°C, and 400 mL / min of nitrogen was introduced from the bottom of the vertical tube furnace, so that the mixed rare earth concentrate was fluidized and roasted for 65 min in an environment of nitrogen as a fluidizing gas to obtain a roasted product; (2) cooling the calcined product to room temperature under the protection of nitrogen to obtain a final calcined product; (3) ball milling the calcined product for 1 hour to complete a primary mechanical activation treatment of the calcined product, and obtaining a primary activated product with a particle size of 400 mesh accounting for more than 99% of the total weight; (4) adding an acidic leaching solution to the primary activation product so that the liquid-to-solid ratio of the acidic leaching solution to the primary activation product is 12:1, and stirring the mixture at a temperature of 75° C. and a stirring speed of 600 r / min for 20 min to obtain a hydrochloric acid leaching mixture including an acidic leaching solution containing rare earth and fluorine elements and a leaching residue containing monazite; wherein the acidic leaching solution includes a first hydrochloric acid solution with a concentration of 3 mol / L and an AlCl3 solution with a concentration of 0.4 mol / L; (5) filtering the hydrochloric acid leaching mixture in sequence, and then washing it with hot water at 75° C. to obtain an acidic leaching solution containing rare earth and fluorine elements, and a leaching residue containing monazite; (6) drying the washed monazite-containing leaching residue in an oven at 80° C., and then ball milling it in a ball mill for 1 h to complete a secondary mechanical activation treatment of the monazite-containing leaching residue, thereby obtaining a secondary activation product with a particle size of 400 mesh accounting for more than 99% of the total weight; (7) adding sodium hydroxide sub-molten salt prepared by sodium hydroxide solution with a mass fraction of 70% as an alkaline leaching solution to the secondary activation product, so that the liquid-to-solid ratio of the alkaline leaching solution to the secondary activation product is 5:1, and stirring the mixture at a temperature of 160°C and a stirring speed of 400 r / min for 120 min to obtain an alkaline leaching mixture of a leaching solution containing phosphorus elements and a leaching residue containing rare earth elements; wherein the leaching solution containing phosphorus elements can be treated to recover the alkaline solution; (8) filtering the alkaline leaching mixture in sequence, and then washing it with hot water at 60°C to obtain a leaching solution containing phosphorus elements and a leaching residue containing rare earth elements; (9) adding a second hydrochloric acid solution having a temperature of 60°C and a concentration of 2 mol / L to the leached residue containing rare earth elements, so that the liquid-to-solid ratio of the second hydrochloric acid solution to the leached residue containing rare earth elements is 10:1, so that the second hydrochloric acid solution dissolves the leached residue containing rare earth elements to obtain an acidic solution containing rare earth elements.

[0057] In this embodiment, the total leaching rate of the rare earth element-containing leaching solution (the rare earth element-containing leaching solution includes the rare earth element-containing acidic leaching solution in step (5) and the rare earth element-containing acidic solution in step (9)) is 93.44%, wherein the leaching rate of fluorine in the fluorine element acidic leaching solution in step (5) is 97.66%, and the leaching rate of phosphorus in the phosphorus element-containing leaching solution in step (8) is 92.15%.

[0058] Comparative Example 1 A fluidized roasting-leaching method for mixed rare earth concentrate comprises the following steps: (1) A mixed rare earth concentrate with a REO grade of 59.24%, a F grade of 6.21%, and a P grade of 5.54% was added into a vertical tube furnace at 550°C, and 400 mL / min of air was introduced from the bottom of the vertical tube furnace, so that the mixed rare earth concentrate was fluidized and roasted for 20 min in an environment where air was used as a fluidizing gas to obtain a roasted product; (2) cooling the calcined product to room temperature under the protection of air to obtain a final calcined product; (3) ball milling the calcined product for 1 hour to complete a primary mechanical activation treatment of the calcined product, and obtain a primary activated product with a particle size of 400 mesh accounting for more than 99% of the total weight; (4) adding an acidic leaching solution to the primary activation product so that the liquid-to-solid ratio of the acidic leaching solution to the primary activation product is 12:1, and stirring the mixture at a temperature of 75° C. and a stirring speed of 600 r / min for 20 min to obtain a hydrochloric acid leaching mixture including an acidic leaching solution containing rare earth and fluorine elements and a leaching residue containing monazite; wherein the acidic leaching solution includes a first hydrochloric acid solution with a concentration of 3 mol / L and an AlCl3 solution with a concentration of 0.4 mol / L; (5) filtering the hydrochloric acid leaching mixture in sequence, and then washing it with hot water at 75° C. to obtain an acidic leaching solution containing rare earth and fluorine elements, and a leaching residue containing monazite; (6) drying the washed monazite-containing leaching residue in an oven at 80° C., and then ball milling the monazite-containing leaching residue in a ball mill for 1 h to complete secondary mechanical activation treatment of the monazite-containing leaching residue, thereby obtaining a secondary activation product with a particle size of 400 mesh accounting for more than 99% of the total weight; (7) adding sodium hydroxide sub-molten salt prepared by sodium hydroxide solution with a mass fraction of 70% as an alkaline leaching solution to the secondary activation product, so that the liquid-to-solid ratio of the alkaline leaching solution to the secondary activation product is 5:1, and stirring the mixture at a temperature of 180°C and a stirring speed of 400 r / min for 120 min to obtain an alkaline leaching mixture of a leaching solution containing phosphorus elements and a leaching residue containing rare earth elements; wherein the leaching solution containing phosphorus elements can be treated to recover the alkaline solution; (8) filtering the alkaline leaching mixture in sequence, and washing it with hot water at 60°C to obtain a leaching solution containing phosphorus elements and a leaching residue containing rare earth elements; (9) adding a second hydrochloric acid solution having a temperature of 60°C and a concentration of 2 mol / L to the leached residue containing rare earth elements, so that the liquid-to-solid ratio of the second hydrochloric acid solution to the leached residue containing rare earth elements is 10:1, so that the second hydrochloric acid solution dissolves the leached residue containing rare earth elements to obtain an acidic solution containing rare earth elements.

[0059] The total leaching rate of the rare earth element-containing leaching solution finally obtained in this comparative example (the rare earth element-containing leaching solution includes the rare earth element-containing acidic leaching solution in step (5) and the rare earth element-containing acidic solution in step (9)) is 92.57%, wherein the leaching rate of fluorine element in the fluorine element acidic leaching solution in step (5) is 89.35%, and the leaching rate of phosphorus element in the phosphorus element leaching solution in step (8) is 92.38%.

[0060] Comparative Example 2 A fluidized roasting-leaching method for mixed rare earth concentrate comprises the following steps: (1) A mixed rare earth concentrate with a REO grade of 59.24%, a F grade of 6.21%, and a P grade of 5.54% was added into a vertical tube furnace at 700°C, and 400 mL / min of nitrogen was introduced from the bottom of the vertical tube furnace, so that the mixed rare earth concentrate was fluidized and roasted for 65 min in an environment of nitrogen as a fluidizing gas to obtain a roasted product; (2) cooling the calcined product to room temperature under the protection of nitrogen to obtain a final calcined product; (3) adding an acidic leaching solution to the roasted product so that the liquid-to-solid ratio of the acidic leaching solution to the roasted product is 12:1, and stirring the mixture at a temperature of 75° C. and a stirring speed of 600 r / min for 20 min to obtain a hydrochloric acid leaching mixture including an acidic leaching solution containing rare earth and fluorine elements and a leaching residue containing monazite; wherein the acidic leaching solution includes a first hydrochloric acid solution with a concentration of 3 mol / L and an AlCl3 solution with a concentration of 0.4 mol / L; (4) filtering the hydrochloric acid leaching mixture in sequence, and then washing it with hot water at 75° C. to obtain an acidic leaching solution containing rare earth and fluorine elements, and a leaching residue containing monazite; (5) adding sodium hydroxide sub-molten salt prepared by a sodium hydroxide solution with a mass fraction of 70% as an alkaline leaching solution to the monazite-containing leaching residue, so that the liquid-to-solid ratio of the alkaline leaching solution to the monazite-containing leaching residue is 5:1, and stirring the mixture at a temperature of 180°C and a stirring speed of 400 r / min for 120 min to obtain an alkaline leaching mixture of a phosphorus-containing leaching solution and a rare earth element-containing leaching residue; wherein the phosphorus-containing leaching solution can be treated to recover the alkaline solution; (6) filtering the alkaline leaching mixture in sequence, and then washing it with hot water at 60°C to obtain a leaching solution containing phosphorus elements and a leaching residue containing rare earth elements; (7) adding a second hydrochloric acid solution having a temperature of 60°C and a concentration of 2 mol / L to the leached residue containing rare earth elements, so that the liquid-to-solid ratio of the second hydrochloric acid solution to the leached residue containing rare earth elements is 10:1, so that the second hydrochloric acid solution dissolves the leached residue containing rare earth elements to obtain an acidic solution containing rare earth elements.

[0061] The total leaching rate of the rare earth element-containing leaching solution finally obtained in this comparative example (the rare earth element-containing leaching solution includes the rare earth element-containing acidic leaching solution in step (5) and the rare earth element-containing acidic solution in step (9)) is 86.68%, wherein the leaching rate of fluorine element in the fluorine element acidic leaching solution in step (5) is 87.24%, and the leaching rate of phosphorus element in the phosphorus element leaching solution in step (8) is 83.36%.

[0062] It can be seen from the above-mentioned embodiments and comparative examples that the present invention adopts a fluidized roasting treatment of the mixed rare earth concentrate under an inert gas atmosphere, so that the fluorocarbon cerium ore (REFCO3) in the mixed rare earth concentrate can be directionally converted into cerium oxide (REOF) which is more easily acid leached. By subjecting the roasted product to a primary mechanical activation treatment and subjecting the leached residue containing monazite to a secondary mechanical activation treatment, the activities of the primary activation product and the secondary activation product obtained can be improved, which is beneficial to the acid leaching of the primary activation product and the alkaline leaching of the secondary activation product, and realizes the effective separation of the rare earth elements, phosphorus and fluorine in the mixed rare earth concentrate, and improves the leaching rate of the rare earth elements, phosphorus and fluorine in the mixed rare earth concentrate.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fluidized roasting-leaching method for mixed rare earth concentrate, characterized in that: include: Fluidized roasting of the mixed rare earth concentrate under an inert gas to convert the bastnaesite phase in the mixed rare earth concentrate into cerium oxyfluoride to obtain a roasting product; Performing a mechanical activation treatment on the calcined product to obtain a primary activated product; The primary activation product is subjected to an acid leaching reaction to obtain an acid leaching product; the acid leaching product comprises an acid leaching solution containing rare earth elements and fluorine elements, and a leaching residue containing monazite; The monazite-containing leached residue is subjected to secondary mechanical activation treatment to obtain a secondary activation product; The secondary activation product is subjected to alkaline leaching treatment to obtain an alkaline leaching product; the alkaline leaching product includes a leaching solution containing phosphorus elements and a leaching residue containing rare earth elements; The method comprises the following steps: fluidizing and roasting the mixed rare earth concentrate under an inert gas to convert the bastnaesite phase in the mixed rare earth concentrate into cerium fluoride oxide to obtain a roasting product, comprising: The mixed rare earth concentrate is fluidized roasted in an inert gas atmosphere at a temperature of 500 to 800° C. for 20 to 120 min to obtain a roasted product; wherein the gas flow rate of the inert gas is 300 to 1000 mL / min; The calcined product is cooled to room temperature under the protection of the inert gas to obtain a final calcined product.

2. The fluidized roasting-leaching method of mixed rare earth concentrate according to claim 1, characterized in that: The particle size of the primary activation product accounting for more than 99% of the total weight is 350-450 meshes; correspondingly, the particle size of the secondary activation product accounting for more than 99% of the total weight is 350-450 meshes.

3. The fluidized roasting-leaching method of mixed rare earth concentrate according to claim 1, characterized in that: The primary activation product is subjected to an acid leaching reaction to obtain an acid leaching product, comprising: Adding hydrochloric acid leaching solution to the primary activation product, stirring at a temperature of 60 to 100° C. and a stirring speed of 200 to 600 r / min for 20 to 120 min to obtain a hydrochloric acid leaching mixture; The hydrochloric acid leaching mixture is filtered and washed in sequence to obtain the acidic leaching solution containing rare earth and fluorine elements and the leaching residue containing monazite.

4. The fluidized roasting-leaching method of mixed rare earth concentrate according to claim 3, characterized in that: The liquid-solid ratio of the hydrochloric acid leaching solution and the primary activation product is 6-20:1; the hydrochloric acid leaching solution includes a first hydrochloric acid solution with a concentration of 2-8 mol / L and a complexing agent solution with a concentration of 0.1-0.6 mol / L.

5. The fluidized roasting-leaching method of mixed rare earth concentrate according to claim 4, characterized in that: The complexing agent is one or more of AlCl3, boric acid and borate.

6. The fluidized roasting-leaching method of mixed rare earth concentrate according to claim 1, characterized in that: The secondary activation product is subjected to alkaline leaching treatment to obtain an alkaline leaching product, comprising: Adding an alkaline leaching solution to the secondary activation product, stirring the mixture at a temperature of 160 to 200° C. and a stirring speed of 300 to 600 r / min for 100 to 160 min to obtain an alkaline leaching mixture; The alkaline leaching mixture is filtered and washed in sequence to obtain the leaching solution containing phosphorus elements and the leaching residue containing rare earth elements.

7. The fluidized roasting-leaching method of mixed rare earth concentrate according to claim 6, characterized in that: The liquid-solid ratio of the alkaline leaching solution and the secondary activation product is 3-5:1; the alkaline leaching solution is a sodium hydroxide sub-molten salt prepared with a sodium hydroxide solution with a mass fraction of 40%-80%.

8. The fluidized roasting-leaching method of mixed rare earth concentrate according to any one of claims 1 to 7, characterized in that: Also includes: A second hydrochloric acid solution with a temperature of 50-70° C. is added to the leached residue containing the rare earth elements, so that the second hydrochloric acid solution dissolves the leached residue containing the rare earth elements to obtain an acidic solution containing the rare earth elements.

9. The fluidized roasting-leaching method of mixed rare earth concentrate according to claim 8, characterized in that: The liquid-to-solid ratio of the second hydrochloric acid solution to the leached residue containing rare earth elements is 8 to 12:1; the concentration of the second hydrochloric acid solution is 1.5 to 2.5 mol / L.

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