Process for the preparation of rare earth and illite products from low carbon illite type rare earth ores

Abstract

The present application belongs to the technical field of comprehensive utilization of illite type rare earth ore, and particularly relates to a method for preparing rare earth and illite product from illite type rare earth ore with low carbon, which comprises the following steps: S1, grinding: grinding the illite type rare earth ore to 60% to 90% of 0.074 mm; S2, alkali excitation activation: adding the illite type rare earth ore into a NaOH and / or KOH solution to perform alkali excitation activation reaction, and obtaining a rare earth-rich illite product residue; S3, whitening leaching: adding the rare earth-rich illite product residue into sulfuric acid or hydrochloric acid to perform leaching, and obtaining a rare earth leaching solution and an illite concentrate after filtering with a mixed filter aid. The present application eliminates the roasting process commonly used in traditional sedimentary rare earth ore, has no tailing residue discharge, reduces the production energy consumption, has less impurity content in the product, and the used solution can be recycled multiple times, and the whole process is green and environmentally friendly.

Description

Technical Field

[0001] This invention belongs to the field of comprehensive utilization technology of illite-type rare earth minerals, specifically relating to a method for low-carbon preparation of rare earth and illite products from illite-type rare earth minerals. Background Technology

[0002] Rare earth elements possess unique electron configurations and are crucial components in many high-tech products, primarily used in green and renewable energy, electric vehicles, glass polishing, and ceramics. However, due to variations in rare earth content and the difficulty of beneficiation and recovery, only a few types of rare earth mines, such as bastnaesite, monazite, and ion-adsorption rare earth deposits, are currently under large-scale commercial development. Because these conventional deposits have limited reserves, they are unlikely to meet the demand for rare earth products in the foreseeable future. Illite, a 2:1 type layered silicate mica mineral composed of two silicon-oxygen tetrahedra and one aluminum-oxygen octahedron, possesses corrosion resistance and heat resistance properties and can be used to produce potash fertilizers, high-grade coatings and fillers, and ceramic components.

[0003] A research team has discovered a novel type of rare earth deposit, named "Paleocontinental Sedimentary Rare Earth Deposits," widely distributed in the ancient continental sedimentary facies of the Sichuan-Yunnan-Guizhou border region. This is a new type of rare earth deposit discovered after ion-adsorption rare earth deposits. The paleocontinental sedimentary rare earth deposits are hosted in the claystone series at the bottom of the Xuanwei Formation of the Permian System in the Sichuan-Yunnan-Guizhou border region, with an average rare earth oxide grade of 0.39% and a wide distribution. Based on ore type, these sedimentary rare earth deposits can be divided into kaolinite-type and illite-type rare earth deposits. Rare earth elements are mainly "bound" in the form of nano-mineral particles within the layered structure of clay minerals (kaolinite or illite). Conventional physical beneficiation methods cannot achieve the enrichment and recovery of rare earths. Furthermore, the leaching rate of rare earths directly using traditional ammonium salt and sulfuric acid systems is extremely low (Gong Daxing et al. Discovery and Significance of Paleocontinental Sedimentary Rare Earths in the Sichuan-Yunnan-Guizhou Border Region).

[0004] Due to the relatively recent discovery of sedimentary rare earth deposits, there are few reports on the extraction of rare earth elements from illite-type rare earth deposits, only a few reports on the extraction of rare earth elements from kaolinite-type rare earth deposits. Patent CN 109266839 A describes a method for recovering sedimentary rare earths by high-temperature roasting of sedimentary rare earth deposits where rare earth elements are mainly present in kaolinite minerals in the form of isomorphous substitution. This transforms the kaolinite into a metakaolinite structure, followed by leaching to obtain a rare earth feed solution. For example, patent CN 114134348 A invented a method for recovering sedimentary rare earths using a direct hot high-acid leaching process. This method uses high-concentration sulfuric acid (40-100% by volume) at 60-300℃ to directly leach aluminum and rare earths simultaneously. After filtration, ammonium sulfate is added to the leachate for reaction. After filtration, crude ammonium aluminum sulfate and crystallization tailings are obtained. The crystallization tailings are then extracted and back-extracted to obtain a coarse mixed rare earth slag. For example, patent CN 115058609A involves mixing a weathered basalt crust sample with concentrated sulfuric acid, roasting it at 120℃-250℃, and then leaching it with dilute sulfuric acid to obtain a rare earth leachate. As can be seen, kaolinite-type rare earth ores are leached by destroying the mineral structure through processes such as roasting or sulfuric acid ripening. While these methods can also leach rare earth elements from illite-type rare earth ores, the roasting process is costly and damages the illite mineral structure, hindering the comprehensive recovery of illite products.

[0005] In summary, this invention provides a method for selectively leaching rare earth and illite products from illite-type rare earth ores (TREO content of 0.1-1.6%, illite content of 85-96%, and TFe content of 0.1-1%) that is non-roasting, tailings-free, low-cost, and simple in process. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing rare earth and illite products from illite-type rare earth ores with low carbon content.

[0007] The objective of this invention is achieved through the following technical solution: a method for preparing rare earth and illite products from illite-type rare earth ores using low-carbon methods, comprising the following steps:

[0008] S1. Grinding: Grind illite-type rare earth ore to a thickness of -0.074 mm, accounting for 60% to 90%;

[0009] S2, Alkali activation: The ground illite-type rare earth ore is added to NaOH and / or KOH solution for alkaline activation reaction, and filtered to obtain rare earth-rich illite product residue and activation waste liquid;

[0010] The activation reaction is carried out at a temperature of 60–100°C, for a reaction time of 30–75 min, with a volume fraction of NaOH and / or KOH of 25–40%, and a liquid-to-solid ratio of 2–6 L / kg.

[0011] S3. Whitening Leaching: The rare earth-rich illite product residue is added to sulfuric acid or hydrochloric acid for leaching. After completion, the solution is mixed with a filter aid solution and filtered to obtain rare earth leachate and illite concentrate.

[0012] The filter aid is one or more of polyethyleneimine, polyacrylamide and polyethylene glycol, and is used in the form of a filter aid solution. The dosage of the filter aid is 3-10 mg / L.

[0013] Furthermore, the illite-type rare earth ore has a TREO content of 0.1–1.6%, an illite content of 85–96%, and a TFe content of <1%.

[0014] Furthermore, in step S2, the activated waste liquid is recycled after being replenished with NaOH and / or KOH.

[0015] Furthermore, in step S3, the leaching time is 0.5-3 hours, the temperature is 30-60°C, the concentration of sulfuric acid or hydrochloric acid is 0.5-2 mol / L, and the liquid-to-solid ratio is 3-6 L / kg.

[0016] The principle of this invention is as follows: This invention targets illite-type rare earth ore, the main characteristic of which is that rare earth elements are mainly "bound" in the form of nano-mineral particles within the layered structure of clay minerals (kaolinite or illite). Therefore, this invention slightly disrupts the interlayer structure of illite using a hot, strong alkaline solution, simultaneously releasing the rare earth carrier minerals (or rare earth ions existing in isomorphous forms) bound within the illite layers and converting them into rare earth hydroxides. Finally, the rare earth leachate is obtained through dilute acid leaching, which simultaneously improves the whiteness of illite, effectively enhancing the quality of the illite raw material. Kaolinite has a relatively compact internal structure with no ionic charge balance between crystal layers and a small ion exchange capacity. Water does not easily penetrate into the middle of the crystal layers. Therefore, the kaolinite unit cell in kaolinite-type rare earth ores has low mobility. Without changing the kaolinite structure, rare earth elements are difficult to release. A roasting temperature above 550℃ is required to transform the kaolinite structure into a metakaolinite structure, thereby releasing rare earth elements. On the other hand, illite-type rare earth ores have more defects in their illite structure. Because potassium ions are needed to balance the charge between the layers, the layers are far apart. Therefore, the illite structure can be slightly damaged by a hot strong alkaline solution without roasting, releasing the rare earth elements stored in the layers.

[0017] This invention employs a non-roasting process to selectively extract rare earth elements from illite-type rare earth ores, while simultaneously obtaining high-whiteness illite concentrate products. It overcomes the shortcomings of traditional roasting extraction processes for sedimentary rare earth ores, such as high energy consumption, complex process flow, and low utilization of tailings. This invention provides a non-roasting comprehensive utilization process for sedimentary rare earth ores, primarily composed of illite.

[0018] The beneficial effects of this invention are:

[0019] 1. This invention first uses a hot alkaline solution to slightly disrupt the layered structure of illite, mainly to release the rare earth carrier minerals (or rare earth ions existing in isomorphous forms) bound in the interlayers and convert them into rare earth hydroxide. The silicon-oxygen tetrahedra and aluminum-oxygen octahedra composed of the main elements Si and Al in the layered structure of illite are not destroyed. Then, dilute acid is used to leach the conversion residue, and the resulting rare earth leachate has fewer impurities. At the same time, acid washing can remove impurities such as iron, thereby increasing the whiteness of illite and achieving the effect of iron removal and whitening. Compared with the method of roasting illite into clinker, it is not possible to comprehensively utilize illite-type rare earth ore. However, this invention obtains a high-whiteness illite concentrate product, which is conducive to broadening the application range of illite-type rare earth ore.

[0020] 2. This invention eliminates the roasting process commonly used in traditional sedimentary rare earth ores, and produces no tailings, significantly reducing production energy consumption. Furthermore, the NaOH, KOH, and sulfuric acid solutions can be recycled multiple times, making the entire process low-carbon and environmentally friendly. Attached Figure Description

[0021] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0022] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the following description.

[0023] Example 1

[0024] Take 1000g of illite-type rare earth ore, with a rare earth element grade of 0.43%, an illite content of 89.2%, and a TFe content of 0.13%.

[0025] Step 1, Grinding: Grind the illite-type rare earth ore to a particle size of -0.074mm, which accounts for 61%;

[0026] Step 2, Alkali activation: The ground illite-type rare earth ore is added to a NaOH solution for reaction. The volume fraction of NaOH is 25%, the reaction temperature is 100℃, the reaction time is 30 min, and the liquid-to-solid ratio is 6 L / kg. 938.2 g of rare earth-rich illite slag and activation waste liquid are obtained.

[0027] Step 3, Whitening Leaching: The rare earth-rich illite slag was added to a sulfuric acid solution with a concentration of 0.5 mol / L for 3 hours at 30°C and a liquid-to-solid ratio of 3 L / kg. After the reaction, the solution was mixed with a 1:1 mixture of 27.7 mg polyacrylamide and polyethylene glycol. After filtration, a rare earth leaching solution was obtained with a rare earth leaching rate of 91.9% and a TREO concentration of 1404 mg / L (aluminum leaching rate of 4.1%). The rare earth leaching solution was then used to produce rare earth products according to conventional process steps. 924.7 g of illite concentrate was obtained (TFe removal rate of 98.7%, SiO2 content of 50.8%, and whiteness increased from 80 to 89.1 of the original ore), with an illite recovery rate of 87.8%.

[0028] Example 2

[0029] The activated waste liquid obtained in step 2 of Example 1 was supplemented with NaOH to a volume fraction of 30%. 1000g of illite-type rare earth ore was taken, with a rare earth element grade of 1.56%, an illite content of 95.8%, and a TFe content of 0.97%.

[0030] Step 1, Grinding: Grind the illite-type rare earth ore to a particle size of -0.074mm, with 80% of the particles being fine.

[0031] Step 2, Alkali activation: The ground illite-type rare earth ore is added to the above 30% NaOH solution for reaction. The reaction temperature is 60℃, the time is 50min, and the liquid-solid ratio is 4L / kg, to obtain 941.4g of rare earth-rich illite slag.

[0032] Step 3, Whitening Leaching: The rare earth-rich illite slag is added to a sulfuric acid solution with a concentration of 1 mol / L for 2 hours at a temperature of 40°C and a liquid-to-solid ratio of 6 L / kg. After the reaction, the solution is mixed with a solution containing 16.7 mg of polyacrylamide and filtered to obtain a rare earth leachate with a rare earth leaching rate of 92.7% and a TREO concentration of 2513.7 mg / L (aluminum leaching rate of 5.2%). The rare earth leachate is then subjected to simple impurity removal, carbonization, and calcination processes to obtain a mixed rare earth oxide product. The whitening leaching step also yields 913.9 g of illite concentrate (TFe removal rate of 98.9%, SiO2 content of 51.4%, and whiteness increased from 81 to 89.5 of the original ore), with an illite recovery rate of 86.8%.

[0033] Example 3

[0034] Take 1000g of illite-type rare earth ore, with a rare earth element grade of 0.98%, an illite content of 85.2%, and a TFe content of 0.75%.

[0035] Step 1, Grinding: Grind the illite-type rare earth ore to a particle size of -0.074mm (90%).

[0036] Step 2, Alkali activation: The ground illite-type rare earth ore is added to a 40% KOH solution for reaction, and the temperature is slowly raised to 60℃ for 70 min. The liquid-to-solid ratio is 3 L / kg, and 940.1 g of rare earth-rich illite slag is obtained.

[0037] Step 3, Whitening Leaching: The rare earth-rich illite slag is added to a sulfuric acid solution with a concentration of 2 mol / L for 0.5 h at a temperature of 60 °C and a liquid-to-solid ratio of 4 L / kg. After the reaction, the solution is mixed with a solution containing 11 mg of polyethyleneimine. After filtration, a rare earth leaching solution is obtained with a rare earth leaching rate of 92.2% and a TREO concentration of 2402.8 mg / L (aluminum leaching rate of 5.9%). The rare earth leaching solution undergoes simple impurity removal, carbonization, and calcination processes to obtain a mixed rare earth oxide product. The whitening leaching step also yields 917.9 g of illite concentrate (TFe removal rate of 98.7%, SiO2 content of 51.2%, and whiteness increased from 80.8% of the original ore to 89%), with an illite recovery rate of 87.2%.

[0038] Comparative Example 1 (the difference from Example 1 is that calcination was used instead of alkali activation)

[0039] Comparative Example 1 and Example 1 used the same raw ore, and the process steps were as follows:

[0040] Step 1, Grinding: Grind the illite-type rare earth ore to a particle size of -0.074mm, which accounts for 61%;

[0041] Step 2, roasting: The ground illite-type rare earth ore is roasted at 650℃ for 3 minutes to obtain 920.5g of roasted sand;

[0042] Step 3, Leaching: The rare earth-rich illite slag was added to a sulfuric acid solution with a concentration of 0.5 mol / L for 3 hours at 30°C and a liquid-to-solid ratio of 3 L / kg. After the reaction, the solution was mixed with a 1:1 mixture containing 23.7 mg of polyacrylamide and polyethylene glycol. After filtration, a rare earth leachate was obtained with a rare earth leaching rate of 92.4% and a TREO concentration of 1438.7 mg / L (aluminum leaching rate of 52.8%). The rare earth leachate was then used to produce rare earth products according to conventional process steps. Simultaneously, 790.5 g of unusable waste residue was obtained, with an illite recovery rate of <1%.

[0043] Compared to Example 1, Comparative Example 1 consumed a large amount of energy during the roasting process; the rare earth product obtained by final enrichment contained higher levels of impurities such as iron and aluminum, and the subsequent purification steps were more complex; and a large amount of waste residue that was difficult to utilize was also generated.

[0044] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A method for preparing rare earth and illite products from illite-type rare earth ores using low-carbon methods, characterized in that, Includes the following steps: S1. Grinding: Grind illite-type rare earth ore to a thickness of -0.074 mm, accounting for 60% to 90%; S2, Alkali activation: The ground illite-type rare earth ore is added to NaOH and / or KOH solution for alkaline activation reaction, and filtered to obtain rare earth-rich illite product residue and activation waste liquid; The activation reaction is carried out at a temperature of 60–100°C, for a reaction time of 30–75 min, with a volume fraction of NaOH and / or KOH of 25–40%, and a liquid-to-solid ratio of 2–6 L / kg. S3, Whitening Leaching: The rare earth-rich illite product residue is added to sulfuric acid or hydrochloric acid for leaching. After completion, the solution is mixed with a filter aid solution and filtered to obtain rare earth leachate and illite concentrate. The filter aid is one or more of polyethyleneimine, polyacrylamide, and polyethylene glycol, and is used in the form of a filter aid solution, with a dosage of 3-10 mg / L.

2. The method for preparing rare earth and illite products from illite-type rare earth ore with low carbon content according to claim 1, characterized in that, The illite-type rare earth ore has a TREO content of 0.1-1.6%, an illite content of 85-96%, and TFe < 1%.

3. The method for preparing rare earth and illite products from illite-type rare earth ore with low carbon content according to claim 1, characterized in that, In step S2, the activated waste liquid is recycled after being replenished with NaOH and / or KOH.

4. The method for preparing rare earth and illite products from illite-type rare earth ore with low carbon content according to claim 1, characterized in that, In step S3, the leaching time is 0.5-3 hours, the temperature is 30-60°C, the concentration of sulfuric acid or hydrochloric acid is 0.5-2 mol / L, and the liquid-to-solid ratio is 3-6 L / kg.

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