Method for suspension roasting-sorting enrichment-staged utilization of sedimentary rare earth ore

Abstract

The present application belongs to the technical field of comprehensive utilization of sedimentary rare earth ore, and particularly relates to a method for suspension roasting-sorting enrichment-stepwise utilization of sedimentary rare earth ore, comprising the following steps: S1, grinding: grinding the sedimentary rare earth ore to 60%-90% of -0.074 mm; S2, suspension roasting: roasting at 550-650 DEG C under a reducing gas atmosphere for 10-25 min to obtain clinker; S3, sorting enrichment: sorting the clinker by magnetic separation to obtain rare earth-niobium-titanium enrichment; S4, stepwise utilization of rare earth: leaching the rare earth-niobium-titanium enrichment with inorganic acid, and filtering after mixing the filter aid to obtain rare earth leaching liquor and niobium-titanium leaching residue; S5, stepwise utilization of niobium and titanium: adding sulfuric acid to the niobium-titanium leaching residue for high-temperature leaching, and filtering after mixing the filter aid to obtain niobium-titanium leaching liquor and silicon-rich leaching residue. The stepwise utilization of rare earth, niobium, titanium and iron elements adopted by the present application can significantly improve the recovery and enrichment effect of each element, greatly reduce the steps and production cost of impurity removal process, and truly realize the comprehensive utilization of various valuable elements of sedimentary rare earth ore.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of comprehensive recovery of sedimentary rare earth ore, and particularly relates to a method for suspension roasting-sorting enrichment-staged utilization of sedimentary rare earth ore. BACKGROUND

[0002] Rare earth elements have a special electronic layer distribution structure and are important components of many high-tech products, mainly applied in the fields of green and renewable energy, electric vehicles, glass polishing and ceramics, and are also indispensable key raw materials for the development of high-tech and national defense cutting-edge technology and strategic emerging industries in the world today. However, due to factors such as different rare earth contents of minerals and large differences in smelting recovery difficulty, only a few rare earth ores such as bastnaesite, monazite, xenotime and ion adsorption type rare earth ore are currently developed on a large scale. Due to the limited reserves of these conventional rare earth ores, they cannot meet the market demand for rare earth products in the foreseeable future. Niobium has excellent electrical conductivity, corrosion resistance and other characteristics, and has extremely wide applications in aerospace, chemical industry and medical industry. Titanium has the characteristics of high temperature resistance, corrosion resistance and good heat exchange, and is known as the third metal and strategic metal after iron and aluminum. Therefore, rare earth, niobium and titanium have become important supports for new material manufacturing and key resources for the development of cutting-edge national defense technology.

[0003] In recent years, a research team has found that the Permian Xuanwei Formation / Longtan Formation in the adjacent Sichuan-Guizhou-Yunnan area has an unconformable contact interface with the top of the overlying Emeishan basalt, and contains key metal elements such as rare earth elements, niobium and titanium. The ore body has obvious enrichment characteristics and is called sedimentary rare earth ore. According to the type of ore, it can be divided into kaolinite type rare earth ore and illite type rare earth ore. The kaolinite type rare earth ore has complex composition, and the rare earth elements are hosted in the layered structure of kaolinite clay rock, and contains iron minerals such as hematite, limonite and magnetite. The main titanium-containing mineral is anatase, and niobium mainly exists in the form of isomorphism in anatase, which is difficult to separate by conventional beneficiation methods (Gong Daxing, et al. Discovery and significance of paleocontinental sedimentary rare earth in the adjacent Sichuan-Guizhou-Yunnan area [J]. Mineral Deposits Geology, 2023, 42(05))(Xu Ying, Dai Zongming, Gong Daxing, et al. Study on the occurrence state of rare earth elements in Permian Xuanwei Formation rich in rare earth rock series in a certain place in Guizhou [J]. Mineral Resources Comprehensive Utilization, 2018, 90(06)).

[0004] Due to the relatively recent discovery of sedimentary rare earth deposits, there are few research reports on them. For example, patent CN114134348A reports a method for recovering sedimentary rare earths using a direct hot high-acid leaching process. This method uses 40-100% sulfuric acid (by volume) at 60-300℃ to directly leach aluminum and rare earth elements together. After filtration, ammonium sulfate is added to the leachate to remove aluminum, yielding crude aluminum ammonium sulfate. The crystallization tailings after aluminum removal are then extracted and back-extracted to obtain crude mixed rare earths. Patent CN 109266839A demonstrates high-temperature roasting and acid leaching of kaolinite-type sedimentary rare earth deposits, achieving selective extraction of rare earth elements and obtaining a rare earth-rich solution. Patent CN 115058609A mixes basalt weathering crust samples with concentrated sulfuric acid, roasts them at 120℃-250℃, and then leaches them with dilute sulfuric acid to obtain a rare earth leachate. For example, patent CN 115109947 A describes the process of calcining and activating the weathered crust of basalt, followed by sulfuric acid leaching to obtain niobium-rich leaching residue. The leaching residue is then ground and mixed with ammonium sulfate, and after staged roasting, sulfuric acid leaching is used to obtain niobium-containing leachate.

[0005] In summary, it is clear that existing processes do not effectively utilize rare earth, niobium, titanium, and iron components simultaneously in kaolinite-type rare earth ores. Therefore, this invention proposes a selective and tiered method for the comprehensive utilization of rare earth, niobium, titanium, and iron components in kaolinite-type rare earth ores (rare earth oxide content is 0.1-1.6%; Nb2O5 content is 0.02-0.04%; TiO2 content is 5-10%; TFe content is 11-22%, mainly existing as hematite, limonite, and magnetite). Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for suspension roasting, sorting and enrichment, and cascade utilization of sedimentary rare earth ores.

[0007] The objective of this invention is achieved through the following technical solution: a method for suspension roasting, sorting and enrichment, and cascade utilization of sedimentary rare earth ores, comprising the following steps:

[0008] S1. Grinding: Grind the sedimentary rare earth ore to a thickness of -0.074 mm, with 60%-90% of the ore being fine.

[0009] S2. Suspension roasting: The ground sedimentary rare earth ore is roasted at 550-650℃ in a reducing gas atmosphere for 10-25 minutes, with an aeration rate of 500-800 mL / min per kilogram of ore, to obtain clinker;

[0010] S3. Sorting and enrichment: The clinker is subjected to magnetic separation with a magnetic separation intensity of 80-130kA / m to obtain iron enrichment and rare earth-niobium-titanium enrichment.

[0011] S4, the rare earth step utilization: the rare earth-niobium-titanium concentrate is inorganic acid leaching, after the reaction is completed, the solution is mixed with the filter aid solution, and the rare earth leaching solution and the niobium titanium leaching residue are obtained by filtration;

[0012] The inorganic acid is sulfuric acid, hydrochloric acid or nitric acid, the inorganic acid concentration is 0.5-2 mol / L, the leaching temperature is 20-60℃, the liquid-solid ratio is 3-7 L / kg, and the leaching time is 1-3 h.

[0013] S5, the niobium titanium step utilization: sulfuric acid is added to the niobium titanium leaching residue for high-temperature leaching, after the leaching is completed, the solution is mixed with the filter aid solution, and the niobium titanium leaching solution and the silicon-rich leaching residue are obtained by filtration.

[0014] The reaction temperature of the high-temperature leaching is 90-120℃, the sulfuric acid solution concentration is 4-7 mol / L, the liquid-solid ratio is 2-6 L / kg, and the time is 0.5-1.5 h.

[0015] Further, the rare earth oxide content in the sedimentary rare earth ore is 0.1-1.6%; the Nb2O5 content is 0.02-0.04%; the TiO2 content is 5-10%, and the TFe content is 11-22%.

[0016] Further, in step S2, the reducing gas atmosphere is composed of a reducing agent and an inert gas, the reducing agent is CO or coal gas; when the reducing agent is CO, the volume ratio of the reducing agent to the reducing gas atmosphere is 15-30%, and the aeration rate is 500-800 mL / min; when the reducing agent is coal gas, the content of H2 and CO accounts for 20-50% of the total volume content of the coal gas.

[0017] Further, in steps S4 and S5, the filter aid is one or more of polyethyleneimine, polyacrylamide and polyethylene glycol, and the filter aid dosage is 3-10 mg / L.

[0018] The principle of the present application is that: the kaolinite type rare earth ore contains kaolinite, magnetite, hematite and limonite and other minerals, and also contains valuable elements such as rare earth, niobium and titanium, if the conventional roasting-leaching process is used, the iron component will be dissolved in large quantities, the leaching solution obtained has high iron content, the subsequent impurity removal and separation process is complex, and the recovery rate of rare earth elements is affected. The limonite and hematite are reduced to form magnetite, and the temperature is controlled at 450-656 DEG C, because the reaction cannot be carried out below 450 DEG C, and above 656 DEG C, FeO is formed (Metallurgical Physical Chemistry Course (second edition)) ; and the kaolinite roasting temperature is lower than 550 DEG C, and the rare earth cannot be leached out, only when the roasting temperature is higher than 550 DEG C, the kaolinite structure can be converted into metakaolinite, and the rare earth elements are released. Therefore, in the present application, the temperature of the suspension roasting is controlled in the range of 550-650 DEG C, which can achieve the purposes of reducing the limonite and hematite to magnetite, converting the kaolinite into metakaolinite, and releasing the rare earth elements. Through roasting transformation and subsequent magnetic separation, iron enrichment and rare earth-niobium-titanium enrichment are obtained. Because the layered structure of the carrier kaolinite of the rare earth ore has been destroyed, the rare earth elements can be released from the layered structure of the kaolinite type clay rock through leaching; and because the niobium and titanium mainly exist in the anatase, they cannot be leached out by low concentration acid solution at low temperature, therefore, by controlling the leaching temperature and acid concentration, the purpose of selective leaching of rare earth can be achieved, and rare earth leaching solution and niobium-titanium leaching residue are obtained; finally, the anatase is dissolved by high temperature sulfuric acid leaching process, and the niobium and titanium elements are released. The present application obtains iron enrichment, rare earth leaching solution, niobium-titanium leaching solution and silicon-rich leaching residue through gradient recovery process, and achieves the purpose of comprehensive utilization of kaolinite type rare earth ore.

[0019] The beneficial effects of the present application are:

[0020] 1. The present application is aimed at a new type of rare earth ore (sedimentary rare earth ore), and four products of iron enrichment, rare earth leaching solution, niobium-titanium leaching solution and silicon-rich leaching residue are obtained, through gradient utilization, not only the target elements are enriched, but also the steps of impurity removal process and production cost are greatly reduced.

[0021] 2. The present application has good selectivity, and through the effective combination of mineral processing and metallurgical process, the iron, rare earth, niobium and titanium in the sedimentary rare earth ore are utilized in gradient, and the comprehensive utilization of various valuable elements in the sedimentary rare earth ore is achieved.

[0022] 3. The suspension roasting in the present application has good controllability and low energy consumption, the limonite and hematite in the sedimentary rare earth ore are reduced to magnetite through roasting, which is convenient for subsequent magnetic separation, and the kaolinite mineral is converted into metakaolinite, which is beneficial to the subsequent leaching of rare earth.

[0023] 4. The leaching rates of niobium, titanium and rare earth in the present application are all greater than 90%, and the leaching extraction effect is excellent.

[0024] 5、The application provides a method for multi-element gradient utilization and effective separation of kaolinite type rare earth ore, and has the characteristics of good selectivity and simple enrichment recovery process. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The process flow chart of the application is shown. DETAILED DESCRIPTION

[0026] The technical solutions of the application will be further described in detail below with reference to the drawings, but the protection scope of the application is not limited to the following description.

[0027] Example 1

[0028] Take 1000g of kaolinite type rare earth ore from a certain place in Guizhou, and the TFe content of the ore is 11.3%, the Nb2O5 content is 0.02%, the TiO2 content is 5.1%, and the rare earth oxide content is 0.14%.

[0029] Step 1, grinding: grind the sedimentary type rare earth ore to 61% of -0.074mm;

[0030] Step 2, suspension roasting: put the ground sedimentary type rare earth ore into a suspension roasting furnace, and under the condition of a temperature of 570℃, pass in 15% concentration of reducing agent CO and 85% concentration of nitrogen gas, the air flow rate is 800mL / min, the roasting time is 10min, and 867.5g of roasting slag is obtained after reaction;

[0031] Step 3, separation and enrichment: the roasted clinker is subjected to weak magnetic separation, and the magnetic separation intensity is 80kA / m, 167.3g of iron enrichment (the iron grade is 48.3%, the yield is 19.3%, and the magnetic separation iron recovery rate is 71.5%) and 696.4g of rare earth-niobium-titanium enrichment (the rare earth-niobium-titanium enrichment ratio is 1.44, and the rare earth, niobium and titanium recovery rates are 98.6%, 99.6% and 99.4% respectively) are obtained;

[0032] Step 4, gradient utilization of rare earth: the clinker is subjected to sulfuric acid leaching, the sulfuric acid concentration is 2mol / L, the temperature is 60℃, the liquid-solid ratio is 3L / kg, and the leaching time is 1h, after the reaction is completed, the solution is mixed with 20.6mg of polyethyleneimine solution, and after filtration, the rare earth leaching solution is obtained, the leaching rate is 93.1%, the TREO concentration is 615.2mg / L (the TFe concentration is 1.5g / L), and at the same time, 688.9g of niobium-titanium leaching slag is obtained (relative to the original ore, the niobium-titanium enrichment ratio is 1.45, and the niobium and titanium recovery rates are 98.5% and 98.3% respectively);

[0033] Step 5, stage utilization of niobium titanium: the niobium titanium leaching residue is put into a sulfuric acid solution and heated and stirred for 0.5 h, the temperature is 120°C, the sulfuric acid concentration is 7 mol / L, the liquid-solid ratio is 3 L / kg, after the reaction is completed, the solution is mixed with a 19.2 mg polyethyleneimine solution, and after filtration, a niobium titanium leaching solution is obtained, the niobium leaching rate is 92.7%, and the concentration is 61.6 mg / L; the titanium leaching rate is 92.4%, and the concentration is 6.2 g / L (TFe concentration is 14 g / L); and a silicon-rich leaching residue of 643.1 g (SiO2 content is 56.5%)

[0034] Example 2

[0035] Take 1000 g of kaolinite type rare earth ore from a certain place in Guizhou, the TFe content of the ore is 21.9%, the Nb2O5 content is 0.04%, the TiO2 content is 9.9%, and the rare earth oxide content is 1.58%

[0036] Step 1, grinding: the sedimentary type rare earth raw ore is ground to -0.074 mm, accounting for 89.8%;

[0037] Step 2, suspension roasting: the ground sedimentary type rare earth is put into a suspension roasting furnace, under the condition of a temperature of 650°C, coal gas is introduced, the gas flow rate is 500 mL / min, and the roasting time is 25 min, and after the reaction, 862.7 g of roasted slag is obtained;

[0038] Step 3, separation and enrichment: the roasted clinker is subjected to weak magnetic separation, the magnetic separation intensity is 130 kA / m, 338.2 g of iron enrichment (iron grade is 49.4%, yield is 39.2%, and magnetic separation iron recovery rate is 76.3%) and 521.5 g of rare earth-niobium-titanium enrichment (rare earth-niobium-titanium enrichment ratio is 1.92, and the rare earth, niobium, and titanium recovery rates are 98.5%, 99.5%, and 99.3%, respectively) are obtained;

[0039] Step 4, stage utilization of rare earth: the clinker is subjected to sulfuric acid leaching, the sulfuric acid concentration is 0.5 mol / L, the temperature is 20°C, the liquid-solid ratio is 7 L / kg, and the leaching time is 3 h, after the reaction is completed, the solution is mixed with a 1:1 mixed solution containing 9 mg of polyacrylamide and polyethylene glycol, and after filtration, a rare earth leaching solution is obtained, the leaching rate is 92.8%, the TREO concentration is 3960.3 mg / L (TFe concentration is 1.4 g / L), and at the same time, 500.1 g of niobium titanium leaching residue is obtained (relative to the raw ore, the niobium-titanium enrichment ratio is 2, and the niobium and titanium recovery rates are 98.4% and 98.2%, respectively);

[0040] Step 5, stage utilization of niobium-titanium: the niobium-titanium leaching residue is put into a sulfuric acid solution and heated and stirred for 1.5 h, the temperature is 90°C, the sulfuric acid concentration is 4 mol / L, the liquid-solid ratio is 6 L / kg, after the reaction is completed, the solution is mixed with a 1:1 mixed solution containing 8.1 mg of polyacrylamide and polyethylene glycol, and a niobium-titanium leaching solution is obtained after filtration, the niobium leaching rate is 92.1%, the concentration is 84.2 mg / L; the titanium leaching rate is 91.9%, the content is 8.2 g / L (TFe concentration is 8.1 g / L); and a silicon-rich leaching residue 499.9 g (SiO2 content is 80.4%)

[0041] Comparative Example 1 (the difference from Example 1 is that air is used instead of the reducing agent CO and nitrogen)

[0042] Comparative Example 1 and Example 1 use the same raw ore, and the process steps are as follows:

[0043] Step 1, grinding: the sedimentary rare earth raw ore is ground to 61% passing 0.074 mm;

[0044] Step 2, suspension roasting: the ground sedimentary rare earth is put into a suspension roaster, air is introduced at a temperature of 570°C, the air flow rate is 800 mL / min, the roasting time is 10 min, and 868.1 roasted slag is obtained after the reaction;

[0045] Step 3, separation and enrichment: the roasted clinker is subjected to low-intensity magnetic separation, the magnetic separation intensity is 80 kA / m, 18.1 g of slag (iron yield is 2.1%, magnetic separation iron recovery rate is 8.7%) and 847.1 g of rare earth-niobium-titanium concentrate (rare earth-niobium-titanium enrichment ratio is 1.18, rare earth, niobium, and titanium recovery rates are 98.7%, 99.7%, and 99.5%, respectively) are obtained;

[0046] Step 4, stage utilization of rare earth: the clinker is subjected to sulfuric acid leaching, the sulfuric acid concentration is 2 mol / L, the temperature is 60°C, the liquid-solid ratio is 3 L / kg, the leaching time is 1 h, after the reaction is completed, the solution is mixed with a 25.1 mg polyethyleneimine solution, and a rare earth leaching solution is obtained after filtration, the leaching rate is 88.1%, the TREO concentration is 479.1 mg / L (TFe concentration is 4 g / L), and at the same time, 833.5 g of niobium-titanium leaching residue is obtained (relative to the raw ore, the niobium-titanium enrichment ratio is 1.2, the niobium and titanium recovery rates are 98.6% and 98.4%, respectively);

[0047] Step 5, stage utilization of niobium-titanium: the niobium-titanium leaching residue is put into a sulfuric acid solution and heated and stirred for 0.5 h, the temperature is 120°C, the sulfuric acid concentration is 7 mol / L, the liquid-solid ratio is 3 L / kg, after the reaction is completed, the solution is mixed with a 21.9 mg polyethyleneimine solution, and after filtration, a niobium-titanium leaching solution is obtained, the niobium leaching rate is 86.8%, and the concentration is 47.7 mg / L; the titanium leaching rate is 86.9%, and the content is 4.8 g / L (the TFe concentration in the solution is 37.2 g / L); and a silicon-rich leaching residue of 727.6 g (the SiO2 content is 50%)

[0048] Comparative Example 2 (and the main difference with Example 1 is that steps 4, 5 are combined)

[0049] Comparative Example 2 and Example 1 use the same raw ore, and the process steps are as follows:

[0050] Step 1, grinding: the sedimentary rare earth raw ore is ground to -0.074 mm, accounting for 61%;

[0051] Step 2, suspension roasting: the ground sedimentary rare earth is put into a suspension roasting furnace, under the condition of a temperature of 570°C, a concentration of 15% reducing agent CO and a concentration of 85% nitrogen gas are introduced, the gas flow rate is 800 mL / min, and the roasting time is 10 min, and after the reaction, 867.8 g of roasting residue is obtained;

[0052] Step 3, separation and enrichment: the roasted clinker is subjected to low-intensity magnetic separation, the magnetic separation intensity is 80 kA / m, 166.9 g of iron concentrate (iron grade 48.1%, yield 19.2%, magnetic separation iron recovery rate 70.9%) and 698.1 g of rare earth-niobium-titanium concentrate (rare earth-niobium-titanium enrichment ratio 1.43, rare earth, niobium, titanium recovery rates are 98.7%, 99.6%, and 99.5%, respectively) are obtained;

[0053] Step 4, leaching: the clinker is put into a sulfuric acid solution and heated and stirred for 0.5 h, the temperature is 120°C, the sulfuric acid concentration is 7 mol / L, the liquid-solid ratio is 3 L / kg, after the reaction is completed, the solution is mixed with a 19.5 mg polyethyleneimine solution, and after filtration, a leaching solution is obtained, the rare earth leaching rate is 91.9%, the TREO concentration is 606.3 mg / L, the niobium leaching rate is 91.8%, and the concentration is 61 mg / L; the titanium leaching rate is 91.5%, and the titanium concentration is 6.1 g / L (the TFe concentration in the solution is 15.7 g / L); and 648.1 g of leaching residue is obtained (the SiO2 content is 56.1%).

[0054] For comparison, the applicant arranges the main data involved in the above examples and comparative examples as follows:

[0055] Table 1 Main data parameters of Examples 1-2 and Comparative Examples 1-3

[0056]

[0057]

[0058] From the above table, compared with Comparative Example 1, the recovery rate of iron and the leaching rate of rare earth, niobium and titanium of Example 1 are obviously improved, and the iron element in the leaching solution is greatly reduced, which shows that the suspension roasting combined with the step-by-step utilization process under the reducing atmosphere can significantly improve the recovery and enrichment effect of each element; compared with Comparative Example 2, although the leaching rate of rare earth, niobium and titanium of Example 1 is close, on the one hand, the step-by-step utilization is realized, and on the other hand, the iron element in the leaching solution is greatly reduced, the steps and production cost of impurity removal process are greatly reduced, and the comprehensive utilization of multiple valuable elements of the sedimentary rare earth ore is truly realized.

[0059] The above description is only the preferred embodiment of the present application, and it should be understood that the present application is not limited to the form disclosed herein, and should not be considered as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein by the above teaching or related art or knowledge. Any modification and change made by those skilled in the art without departing from the spirit and scope of the present application shall be within the protection scope of the claims of the present application.

Claims

1. A method for suspension roasting-separation enrichment-staged utilization of a sedimentary rare earth ore, characterized in that, The method comprises the following steps: S1, grinding: grinding the raw ore of the sedimentary rare earth ore to 60%-90% of -0.074 mm; S2, suspension roasting: roasting the ground sedimentary rare earth ore at 550-650 DEG C under a reducing gas atmosphere for 10-25 min, with a ventilation rate of 500-800 mL / min per kg of ore, to obtain clinker; S3, separation and enrichment: subjecting the clinker to magnetic separation at a magnetic separation intensity of 80-130 kA / m to obtain iron enrichment and rare earth-niobium-titanium enrichment; S4, step-by-step utilization of rare earth: subjecting the rare earth-niobium-titanium enrichment to inorganic acid leaching, mixing the solution with a filter aid solution after the reaction is completed, and filtering to obtain a rare earth leachate and a niobium-titanium leaching residue; wherein the inorganic acid is sulfuric acid, hydrochloric acid or nitric acid, the inorganic acid concentration is 0.5-2 mol / L, the leaching temperature is 20-60 DEG C, the liquid-solid ratio is 3-7 L / kg, and the leaching time is 1-3 h; S5, step-by-step utilization of niobium and titanium: adding sulfuric acid to the niobium-titanium leaching residue for high-temperature leaching, mixing the solution with a filter aid solution after the leaching is completed, and filtering to obtain a niobium-titanium leachate and a silicon-rich leaching residue; wherein the high-temperature leaching temperature is 90-120 DEG C, the sulfuric acid solution concentration is 4-7 mol / L, the liquid-solid ratio is 2-6 L / kg, and the time is 0.5-1.5 h.

2. The method of suspension roasting-grading enrichment-staged utilization of a deposit-type rare earth ore according to claim 1, characterized in that, The sedimentary rare earth ore contains 0.1-1.6% of rare earth oxides, 0.02-0.04% of Nb2O5, 5-10% of TiO2, and 11-22% of TFe.

3. The method of suspension roasting-grading enrichment-staged utilization of a deposit-type rare earth ore according to claim 1, characterized in that, In step S2, the reducing gas atmosphere is composed of a reducing agent and an inert gas, and the reducing agent is CO or coal gas; when the reducing agent is CO, the volume ratio of the reducing agent to the reducing gas atmosphere is 15-30%; when the reducing agent is coal gas, the content of H2 and CO accounts for 20-50% of the total volume content of the coal gas.

4. The method of suspension roasting-grading enrichment-staged utilization of a deposit-type rare earth ore according to claim 1, characterized in that, In steps S4 and S5, the filter aid is used in an amount of 3-10 mg / L, and the filter aid is one or more of polyethyleneimine, polyacrylamide and polyethylene glycol.

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