A method of processing a rare earth concentrate

Abstract

The present application relates to the technical field of rare earth concentrate processing, and particularly relates to a rare earth concentrate processing method. The rare earth concentrate processing method comprises the following steps: mixing and roasting a rare earth concentrate with a calcium-containing compound, silicon dioxide and carbon powder to obtain a roasted ore; adding water to the roasted ore to obtain a slurry; adding acid to the slurry to react, and then performing solid-liquid separation to obtain an acid leaching residue and a rare earth chloride solution. The present application has the advantages of simple process flow, high rare earth recovery rate, short reaction time, green environmental protection, low cost, and diversified applicability of rare earth grade. In the present application, the silicon dioxide can increase the decomposition activity of fluorcarbonate cerium and monazite in the rare earth ore, and can generate a rare earth compound that is easy to leach out, thereby improving the decomposition rate of the rare earth concentrate. Calcium can also play a role in fluorine fixation. The rare earth decomposition rate of the present application is above 98%, and the rare earth leaching rate is above 96%.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rare earth concentrate processing, in particular to a processing method of rare earth concentrate. BACKGROUND

[0002] At present, the main exploitable mineral type rare earth ores are bastnaesite, monazite and mixed rare earth concentrate. The industrialized decomposition technologies of mixed rare earth concentrate mainly include concentrated sulfuric acid high-temperature roasting decomposition process and concentrated alkali solution atmospheric decomposition process. However, the concentrated sulfuric acid high-temperature roasting decomposition process produces a large amount of high-temperature mixed acid tail gas, transformation sulfate wastewater and radioactive waste residue, which are difficult to handle, resulting in a large environmental protection treatment engineering system and high cost. The concentrated alkali solution decomposition process handles mixed rare earth concentrate with a REO grade of about 60%, and produces a large amount of mixed alkali wastewater, which is difficult to recycle, resulting in waste of excess sodium hydroxide. The sodium hydroxide can only be neutralized and discharged into the sea after reaching the standard, and fluorine and phosphorus resources cannot be recovered. In addition, the bastnaesite mainly adopts the oxidation roasting-hydrochloric acid leaching-alkali transformation process, but the process is long and the consumption of acid and alkali is large.

[0003] CN109988903A discloses a method for decomposing high-grade mixed rare earth concentrate by concentrated sulfuric acid two-stage roasting. First, the rare earth concentrate is mixed with concentrated sulfuric acid at a weight ratio of 1:1.3, and then low-temperature roasting is performed at about 380℃ to obtain low-temperature roasted ore. The low-temperature roasted ore is subjected to high-temperature roasting at about 900℃ to obtain high-temperature roasted ore. This method has a long process flow, consumes a large amount of concentrated sulfuric acid, and has a high requirement for the grade of mixed rare earth concentrate.

[0004] CN112981146A discloses a method for recovering rare earth molten salt electrolysis slag by fluorine solidification transformation roasting. First, the fluorine-containing rare earth molten salt electrolysis slag is finely ground to a particle size of 100 mesh or less. Then, the product is mixed with an additive and uniformly mixed, and then subjected to fluorine solidification roasting for about 3 hours. The roasted ore is subjected to acid leaching to obtain acid leaching slag and acid leaching liquid. This method has a high requirement for the particle size of the slag, a long roasting time, and a long process flow, which is not conducive to industrial production.

[0005] CN113564343A discloses a green chemical alkali transformation defluorination method for roasting fluorine-containing rare earth ore and solid slag. The method includes multiple steps such as traditional roasting of fluorine-containing rare earth ore and slag for alkali transformation defluorination, heating and leaching NaF, solid-liquid separation, and heating and leaching of rare earth. Although this method can achieve green chemical defluorination, it has a long process flow and is not easy to implement industrial production.

[0006] CN103184332A discloses a method for decomposing fluorocarbcerate rare earth ore by calcification compound and cover agent roasting, which mixes fluorocarbcerate with calcification compound, covers the exposed surface with cover agent, and roasts at 800-900 DEG C for 2-5 hours. After roasting, hydrochloric acid is added for leaching. The method reacts fluorocarbcerate with calcium to form calcium fluoride, but the solid-solid reaction results in poor conversion rate of rare earth.

[0007] CN109837385A discloses a method for decomposing rare earth ore by heating and melting, which uses monazite as raw material, mixes monazite with petroleum coke, and heats monazite to decompose monazite by electric arc furnace, but does not analyze mixed rare earth concentrate.

[0008] CN115637339A discloses a production process for extracting phosphorus products and rare earth products from monazite rare earth ore, which mixes monazite with carbon powder, adds a binder to make balls, and reacts at 1400 DEG C or above to produce tail gas. The tail gas is oxidized and reacted with hot water to produce phosphoric acid. The smelted ore is dissolved by hydrochloric acid to obtain chlorinated rare earth solution. The invention only studies monazite, and obtains phosphorus and rare earth oxides by carbon thermal reduction of monazite.

[0009] CN110684896A discloses a high-temperature smelting method for decomposing fluorocarbcerium lanthanum ore, which mixes fluorocarbcerium lanthanum ore with a reducing agent to make balls, and then smelts the balls. The smelting equipment has an arc-inducing material, and inert gas is injected during smelting. The inert gas is preferably argon. However, the temperature is above 2000 DEG C, and the equipment requirements are high. SUMMARY

[0010] Based on the above, the present application provides a method for processing rare earth concentrate, which has simple process flow, high rare earth recovery rate, short reaction time, green environmental protection, low cost, and diversified applicability of rare earth grade.

[0011] To achieve the above-mentioned purpose, the present application provides the following solutions.

[0012] The present application provides a method for processing rare earth concentrate, which comprises the following steps:

[0013] Mixing rare earth concentrate with calcium-containing compound, silicon dioxide and carbon powder to obtain roasted ore;

[0014] Adding water to the roasted ore to obtain slurry;

[0015] Adding acid to the slurry to react, and then performing solid-liquid separation to obtain acid leaching residue and chlorinated rare earth solution.

[0016] In some embodiments of the present application, the rare earth concentrate is at least one of fluorocarbcerate, monazite and mixed rare earth concentrate.

[0017] The content of rare earth in the rare earth concentrate is not less than 40% by weight in terms of REO.

[0018] In some embodiments of the present application, the calcium-containing compound is at least one of calcium oxide, calcium hydroxide, calcium sulfate and calcium carbonate.

[0019] The addition amount of the calcium-containing compound is 0-40% of the mass of rare earth in the rare earth concentrate in terms of REO. Preferably, it is 10-40%, more preferably, 30-40%.

[0020] In some embodiments of the present application, the addition amount of the silicon dioxide is 5-60% of the mass of rare earth in the rare earth concentrate in terms of REO. Preferably, it is 10-50%, more preferably, 20-40%.

[0021] In some embodiments of the present application, the addition amount of the carbon powder is 10-40% of the mass of rare earth in the rare earth concentrate in terms of REO. Preferably, it is 10-30%, more preferably, 20-30%.

[0022] In some embodiments of the present application, the temperature of the roasting is 1400-1700℃, and the time is 0.5-4h. Preferably, the temperature of the roasting is 1500-1700℃, more preferably, 1600-1700℃; and the time is preferably 2-4h, more preferably, 3-4h.

[0023] At the roasting temperature, the material is in a molten state, which can make the material mix uniformly, and the material turns into a rare earth-containing compound that is easily soluble in hydrochloric acid after cooling.

[0024] The addition of the carbon powder can make the roasting process proceed in a reducing atmosphere.

[0025] In the present application, the addition of the silicon dioxide can increase the mineral phase transformation of the rare earth concentrate during the roasting process. The rare earth concentrate (including bastnaesite or monazite) and the silicon dioxide act together to transform into a silicate rare earth that is easily leached out. Through the action of the silicon dioxide, the rare earth in the rare earth concentrate is more easily leached out, and the leaching efficiency of the rare earth is improved.

[0026] Before the present application, no one realized that the addition of the silicon dioxide has such an effect on the leaching rate of rare earth in the mixed rare earth concentrate, bastnaesite and monazite. The present application unexpectedly found that the addition of the silicon dioxide can increase the leaching rate of rare earth to more than 96%, and the process is simple. Chlorinated rare earth liquor can be directly obtained by one-step acid leaching, and the acid leaching residue can be returned to roasting, which significantly reduces the amount of waste residue.

[0027] The prior art only aims at the decomposition of fluorocarbonates, compared with the present technology, the decomposed minerals include mixed rare earth concentrate, bastnaesite or monazite, and the minerals are more complex, and compared, the monazite belongs to phosphoric rare earth, and is stable in structure and is difficult to decompose, and the addition of the silicon dioxide can increase the mineral phase transformation of the monazite mineral, so that the rare earth in the monazite mineral is more easily leached out, and the method has high applicability to minerals.

[0028] The step of acid leaching also includes the step of grinding the roasted ore, preferably to 100 mesh.

[0029] In some embodiments of the present application, the solid-liquid ratio of the roasted ore to the water is 1:4-6 (g / mL); further preferably 1:5.

[0030] The temperature of the slurry is 30-80 DEG C. The temperature of the slurry is 30-80 DEG C. by heating, or the temperature of the slurry is regulated by limiting the temperature of the water; the temperature of the slurry is preferably 40-70 DEG C., more preferably 50-60 DEG C.

[0031] In some embodiments of the present application, the acid is hydrochloric acid; the amount of the acid added is to make the hydrogen ion concentration in the reaction system 0.2-0.8 mol / L.

[0032] In some embodiments of the present application, the temperature of the reaction is 30-80 DEG C. and the time is 0.5-2 hours. The reaction time is preferably 1-2 hours, more preferably 2 hours.

[0033] The slurry after acid leaching is subjected to solid-liquid separation operation to obtain acid leaching residue and chlorinated rare earth solution, and the acid leaching residue can be returned to roasting, and under the conditions of the present application, the rare earth in the rare earth concentrate can be maximally extracted into the acid leaching solution, and the REO leaching rate is greater than or equal to 96%.

[0034] The solid-liquid separation can be selected from centrifugation or filtration, preferably filtration.

[0035] The present application provides a treatment method for rare earth concentrate, which has the advantages of simple process flow, high rare earth recovery rate, short reaction time, green environmental protection, low cost, and diversified applicability of rare earth grade.

[0036] The present application has the following technical effects:

[0037] (1) The present application increases the decomposition activity of bastnaesite and monazite in rare earth ore by adding silicon dioxide, and promotes the decomposition of bastnaesite and monazite to generate silicate rare earth.

[0038] (2) The present application preferentially leaches rare earth by regulating the hydrochloric acid leaching conditions, does not produce waste water, and the acid leaching residue can continue to return to the source for further reaction, which can significantly reduce the amount of waste residue.

[0039] (3) The present application does not limit the particle size of the mineral, reduces the grinding step, and widens the smelting range of rare earth minerals.

[0040] (4) Compared with the existing high-temperature decomposition process, the present application has strong applicability to minerals, and can decompose single bastnaesite, single monazite and mixed rare earth concentrate. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0042] Figure 1 The process flow diagram for the rare earth concentrate of the present application. DETAILED DESCRIPTION

[0043] The various exemplary embodiments of the present application will now be described in detail, which should not be considered as limiting the present application, but should be understood as a more detailed description of some aspects, characteristics and embodiments of the present application.

[0044] It should be understood that the terms described in the present application are only for describing the specific embodiments, and are not used to limit the present application. In addition, for the numerical range in the present application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or intermediate value within the range, and any other stated value or intermediate value within the range, is also included in the present application. The upper limit and the lower limit of these smaller ranges can be independently included or excluded from the range.

[0045] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as those commonly understood by one of ordinary skill in the art to which this application pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described. All publications mentioned herein are incorporated by reference to disclose and describe the methods and / or materials in connection with which the publications are cited. In case of conflict between the content of the specification and that of any document incorporated herein by reference, the content of the specification prevails.

[0046] Many modifications and variations of this application can be made in the light of the above teachings without departing from the spirit and scope thereof. Other implementations of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples given are exemplary only.

[0047] As used herein, the terms "comprises", "comprising", "includes", "including", "has", "having", "contains", "containing", or variations thereof, are intended to be open-ended terms that mean inclusion, but not limited to, the listed materials and methods.

[0048] The "%" in the present application, if not specially stated, means mass percent.

[0049] The process flow chart of the rare earth concentrate in the present application is shown in Figure 1

[0050] The analysis method involved in the present application:

[0051] The REO (rare earth oxide) content is analyzed by gravimetric method.

[0052] The F content is analyzed by distillation method.

[0053] The CaO content is analyzed by EDTA titration method.

[0054] The calculation formula of the rare earth leaching rate in the present application = (the mass of REO in the rare earth leaching solution / the mass of REO in the rare earth concentrate) x 100%.

[0055] The technical solutions in the present application, if not specially stated, are the conventional solutions in the art, and the reagents or raw materials used, if not specially stated, are purchased from commercial channels or have been disclosed.

[0056] The hydrochloric acid used in the examples of the present application is industrial hydrochloric acid with mass concentration of 30% to 36%.

[0057] The technical solutions provided by the present application will be described in detail below in combination with examples, but they should not be understood as limiting the scope of protection of the present application.

[0058] Example 1

[0059] ​50g mixed rare earth concentrate (REO content of 57.56%, main rare earth element ratio in REO: CeO2 50.74%, La2O3 27.91%, Pr6O 11 4.83%, Nd2O3 14.44%, CaO content 8.33%, SiO2 content 0.76%, F content 5.99%) was mixed with 30% silica (calculated based on rare earth oxides, i.e. the amount of silica added accounts for 30% of the mass of rare earth oxides), 30% calcium oxide (calculated based on rare earth oxides) and 20% carbon powder (calculated based on rare earth oxides) in a graphite crucible, and the crucible was placed in a muffle furnace and roasted at 1550°C for 2h. After roasting, the roasted ore was ground to 100 mesh and added to 200mL water for slurry preparation and heated to 40°C. 50mL hydrochloric acid was slowly added to the slurry and reacted for 2h. After the reaction, solid-liquid separation was performed to obtain acid leaching residue and rare earth chloride solution. Through calculation, the REO leaching rate was 96.89%, the CeO2 leaching rate was 97.02%, the La2O3 leaching rate was 96.62%, the Pr6O 11 leaching rate was 97.05%, and the Nd2O3 leaching rate was 97.58%.

[0060] Example 2

[0061] The difference from Example 1 is only that the rare earth concentrate used is Weishan fluorocarbon cerium rare earth concentrate in Shandong (REO content of 42.76%, main rare earth element ratio in REO: CeO2 49.47%, La2O3 31.63%, Pr6O 11 4.46%, Nd2O3 12.58%, F content 7.41%, CaO content 13%) was mixed with 40% SiO2 (calculated based on rare earth oxides), 50% CaCO3 (calculated based on rare earth oxides) and 30% carbon powder (calculated based on rare earth oxides), the roasting temperature was 1600°C, the roasting time was 3h, and the rest of the steps and parameters were the same as in Example 1. The rare earth leaching solution was analyzed and tested, and the leaching rates are shown in Table 1.

[0062] Example 3

[0063] The difference from Example 1 is only that the rare earth concentrate used is monazite ore (REO content of 63.21%, main rare earth element ratio in REO: CeO2 51.62%, La2O3 25.53%, Pr6O 11 5.05%, Nd2O3 15.61%, P2O5 content 25.27%, CaO content 0.11%) was mixed with 40% SiO2 (calculated based on rare earth oxides) and 30% carbon powder (calculated based on rare earth oxides), the roasting temperature was 1700°C, the roasting time was 4h, and the rest of the steps and parameters were the same as in Example 1. The rare earth leaching solution was analyzed and tested, and the leaching rates are shown in Table 1.

[0064] Example 4

[0065] The difference between Example 4 and Example 1 is that 20% SiO2 (calculated based on rare earth oxides), 40% Ca(OH)2 (calculated based on rare earth oxides), and 10% carbon powder (calculated based on rare earth oxides) are added, the calcination temperature is 1500°C, and the calcination time is 2 hours. The remaining steps and parameters are the same as those of Example 1. The rare earth leaching solution is analyzed and tested, and the leaching rate is shown in Table 1.

[0066] Comparative Example 1

[0067] The difference between Comparative Example 1 and Example 1 is that no SiO2 is added, and the remaining steps and parameters are the same as those of Example 1. The rare earth leaching solution is analyzed and tested, and the leaching rate is shown in Table 1.

[0068] Comparative Example 2

[0069] The difference between Comparative Example 2 and Example 1 is that 5% SiO2 (calculated based on rare earth oxides) is added, and the remaining steps and parameters are the same as those of Example 1. The rare earth leaching solution is analyzed and tested, and the leaching rate is shown in Table 1.

[0070] From Comparative Example 1 and Comparative Example 2, it can be seen that the leaching rate of rare earths in the rare earth concentrate decreases sharply when no or a small amount of SiO2 is added, which indicates the importance of SiO2 in promoting the leaching of rare earths in the rare earth concentrate according to the technical solution of the present application.

[0071] Table 1 Experimental data of different examples

[0072]

[0073] The above-described examples only describe the preferred modes of the present application and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those of ordinary skill in the art should fall within the protection scope of the present application as defined by the claims.

Claims

1. A method of processing a rare earth concentrate, characterized in that, The steps are as follows: The rare earth concentrate is mixed with a calcium-containing compound, silicon dioxide and carbon powder and then roasted to obtain roasted ore; The roasted ore is mixed with water to obtain slurry; An acid is added to the slurry to react, and then solid-liquid separation is performed to obtain acid leaching residue and rare earth chloride solution; The rare earth concentrate is at least one of bastnaesite, monazite and mixed rare earth concentrate; The content of rare earth in the rare earth concentrate is not less than 40wt% in terms of REO; The calcium-containing compound is at least one of calcium oxide, calcium hydroxide, calcium sulfate and calcium carbonate; The addition amount of the calcium-containing compound is 0-40% of the mass of rare earth in the rare earth concentrate in terms of REO, and is not 0; The roasting temperature is 1400-1700℃, and the time is 0.5-4h; The addition amount of the silicon dioxide is 5-60% of the mass of rare earth in the rare earth concentrate in terms of REO.

2. The method of processing a rare earth concentrate according to claim 1, characterized in that, The addition amount of the carbon powder is 10-40% of the mass of rare earth in the rare earth concentrate in terms of REO.

3. The method of processing a rare earth concentrate according to claim 1, characterized in that, The solid-liquid ratio of the roasted ore to the water is 1:4-6. The temperature of the slurry is 30-80℃.

4. The method of processing a rare earth concentrate according to claim 1, characterized in that, The acid is hydrochloric acid; the addition amount of the acid is to make the hydrogen ion concentration in the reaction system reach 0.2-0.8mol / L.

5. The method of processing a rare earth concentrate according to claim 1, characterized in that, The reaction temperature is 30-80℃, and the time is 0.5-2h.

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