Separation and extraction method of rare earth and titanium in sedimentary rare earth ore

Abstract

The present application relates to the technical field of hydrometallurgy, and particularly relates to a method for separating and extracting rare earth and titanium in a sedimentary rare earth ore. The method comprises the following steps: mixing the sedimentary rare earth ore with acid and then roasting, and then adding into water for leaching, and obtaining slag and rare earth feed liquid A after solid-liquid separation; filtering to obtain titanium oxide and rare earth feed liquid B after standing the rare earth feed liquid A; extracting the rare earth feed liquid B by using an amine extractant to obtain an organic phase; stripping the organic phase, and then precipitating to obtain a precipitate; and calcining the precipitate to obtain rare earth oxide. The present application aims at the defects and deficiencies of the prior art, and provides a method for recovering rare earth and valuable titanium elements in a sedimentary rare earth ore by low-temperature roasting and water leaching. The method has the characteristics of low energy consumption, convenient and controllable operation, and environmental friendliness, and solves the specific technical difficulties of Guizhou sedimentary rare earth ore.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgical technology, and in particular to a method for separating and extracting rare earth elements and titanium from sedimentary rare earth ores. Background Technology

[0002] Rare earth elements are increasingly widely used and have become indispensable elements in many key technologies, such as permanent magnets, superconductors, and renewable energy. They offer performance that current alternative materials cannot match, especially rare heavy rare earth elements. However, commercially viable rare earth deposits are quite scarce. The increasing demand for rare earths and the scarcity of rare earth mineral resources have seriously affected current industrial development and the improvement of people's living standards. Therefore, actively seeking rare earth substitutes and exploring new rare earth deposits and other associated rare earth resources are urgent key issues that need to be addressed. The average grade of rare earth elements in sedimentary rare earth deposits is 0.2%–0.3%, with the most abundant rare earth elements being cerium, lanthanum, neodymium, yttrium, and praseodymium. The contents of key rare earth elements praseodymium, neodymium, terbium, and dysprosium are also high, accompanied by valuable elements such as niobium, zirconium, and gallium, making them highly valuable for development. The newly discovered sedimentary rare earth deposits in Guizhou Province possess unique ore structures and extremely fine-grained main minerals, making it difficult to enrich rare earth elements using conventional physical beneficiation methods. Therefore, there is an urgent need to develop extraction processes suitable for these novel sedimentary rare earth deposits. Currently, most rare earth extraction processes require high-grade rare earth ore, making it difficult to directly extract low-grade sedimentary rare earth deposits using these established processes.

[0003] For high-grade rare earth resources such as monazite, bastnaesite, xenotime, and weathered crust leaching rare earth deposits, relatively mature metallurgical extraction processes have been developed, mainly employing methods such as direct leaching with acid or electrolyte solutions, ammonium sulfate roasting, alkaline cracking, or chlorination. However, for low-grade rare earth ores where the main gangue minerals are complex zirconium silicates, the current primary extraction process is in-situ leaching based on the ion exchange mechanism. This can be achieved using Na-containing... + NH4 + Ca 2+ Mg 2+ Fe 3+ Leaching is performed using various isocationic electrolyte solutions. Among them, ammonium sulfate ((NH4)2SO4) is the most widely used leaching agent. Subsequently, ammonium bicarbonate (NH4HCO3) precipitation is usually used to enrich and recover rare earth elements from the leachate. However, the overflow of ammonia gas during the activation roasting process and the excessive ammonium slag in the tailings cause irreversible pollution to the soil, rivers, and groundwater near the mine, such as ammonia nitrogen pollution. Therefore, in order to reduce the economic and environmental burden and achieve efficient recovery of key rare earth elements, a more environmentally friendly extraction process is needed to achieve efficient recovery of rare earth elements, especially heavy rare earth elements, from new sedimentary rare earth mines in Guizhou Province under milder conditions. Summary of the Invention

[0004] Based on the above, the present invention provides a method for separating and extracting rare earth elements and titanium from sedimentary rare earth ores.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] This invention provides a method for separating and extracting rare earth elements and titanium from sedimentary rare earth ores, comprising the following steps:

[0007] The sedimentary rare earth ore is mixed with acid and roasted, then added to water for leaching. After solid-liquid separation, slag and rare earth liquid A are obtained.

[0008] After allowing the rare earth solution A to stand, it was filtered to obtain titanium oxide and rare earth solution B;

[0009] The rare earth feed solution B was extracted using an amine extractant to obtain an organic phase;

[0010] The organic phase is stripped and then precipitated to obtain a precipitate; the precipitate is calcined to obtain rare earth oxides.

[0011] In a preferred embodiment of the present invention, the liquid-to-solid volume ratio of the sedimentary rare earth ore to the acid is 0.5-2.5:1; the acid is sulfuric acid; and the roasting temperature is 200-320°C for 1-6 hours.

[0012] As the calcination temperature increases, the leaching rate of titanium and rare earth elements gradually increases. As the calcination temperature further increases, the leaching rate of titanium and rare earth elements shows a decreasing trend. Therefore, the preferred calcination temperature of this invention is 200-320℃.

[0013] In a preferred embodiment of the present invention, the liquid-to-solid volume ratio during leaching is 5-25:1; the leaching temperature is 20-100℃ and the leaching time is 1-5h; more preferably, it is 3h.

[0014] In a preferred embodiment of the present invention, the settling time is 5-10 hours; before settling, the step of adding ammonia water to adjust the pH of the rare earth solution A to 2 is also included.

[0015] In a preferred embodiment of the present invention, the amine extractant is at least one of N1923, dodecylamine, octylamine, and isooctylamine.

[0016] In a preferred embodiment of the present invention, the solvent for extraction is sulfonated kerosene; the extraction conditions are: the volume concentration of the amine extractant in the organic phase is 0-10%, and not 0, the O / A ratio is 1:(1-3), the temperature is room temperature, and the extraction time is 1-14 min.

[0017] As the volume concentration of the amine extractant in the organic phase increases, the extraction rate gradually increases. The extraction rate reaches its maximum when the volume concentration of the amine extractant in the organic phase reaches 10%. Further increases in the volume concentration of the amine extractant in the organic phase have no significant impact on the extraction rate. Therefore, considering both extraction efficiency and cost, the preferred volume concentration of the amine extractant in the organic phase in this invention is 0-10%, specifically 5-10% in some embodiments, 8-10% in some embodiments, and 9-10% in some embodiments.

[0018] In this invention, when the O / A ratio is greater than 1:1, the extraction rate remains unchanged; when it is less than 1:1, the extraction rate decreases. Extraction time less than 1 minute results in a lower extraction rate, while extraction time greater than 14 minutes does not significantly change the extraction rate. Therefore, considering both extraction efficiency and cost, this invention preferably limits the O / A ratio and extraction time to the ranges described above.

[0019] In a preferred embodiment of the present invention, tributyl phosphate (TBP) is added during extraction; the volume concentration of TBP during extraction is 0-10%.

[0020] In a preferred embodiment of the present invention, a mixed solution of hydrochloric acid and chloride is used for stripping; the concentration of hydrochloric acid in the mixed solution is 0-1 mol / L, and not 0; the concentration of chloride in the mixed solution is 1-10 mol / L; the stripping temperature is room temperature, and the time is 0.5-60 min; more preferably 5 min; during the stripping, the O / A volume ratio is 1:(1-3); more preferably 1:1.

[0021] In a preferred embodiment of the present invention, oxalic acid or oxalate is used for precipitation; the calcination temperature is 500-1000℃ and the time is 1-3h.

[0022] The present invention discloses the following technical effects:

[0023] The present invention aims to address the defects and deficiencies of the existing technology by providing a method for separating and extracting rare earth and titanium from sedimentary rare earth ores. This method can efficiently recover titanium while recovering rare earth, and features low energy consumption, convenient and controllable operation, and environmental friendliness.

[0024] The method of this invention addresses specific technical challenges in sedimentary rare earth deposits in Guizhou, enabling efficient recovery of rare earth elements and valuable titanium elements under conditions of low-temperature roasting and mild water leaching (with the system pH after leaching being 1-2). Detailed Implementation

[0025] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0026] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0027] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0028] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0029] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0030] Unless otherwise specified, "room temperature" in this invention refers to 20-30°C.

[0031] Unless otherwise specified, the "%" mentioned in this invention refers to a percentage by mass.

[0032] This invention provides a method for separating and extracting rare earth elements and titanium from sedimentary rare earth ores, comprising the following steps:

[0033] (1) The sedimentary rare earth ore in Qianxi area is crushed into ore powder and then mixed with sulfuric acid for sulfidation roasting to obtain the first material; the liquid-to-solid volume ratio of the sulfuric acid to the sedimentary rare earth ore powder is 0.5-2.5:1, the roasting temperature is 200-320℃, and the time is 1-6h; the first material is subjected to water leaching (i.e., water extraction) to obtain the second material; the liquid-to-solid volume ratio of the water leaching is 5-25:1, and the water leaching temperature is 20-100℃; the second material is subjected to solid-liquid separation to obtain slag and rare earth liquid A;

[0034] This invention uses low-temperature sulfuric acid roasting, which avoids the introduction of ammonia nitrogen pollution; and the water leaching conditions are mild, with the pH of the leaching solution around 1-2.

[0035] In this invention, the rare earth leaching rate can reach more than 80%, of which the heavy rare earth leaching rate can reach more than 72%.

[0036] (2) Add ammonia to the rare earth solution A to make the pH 2, let it stand for 5-10 hours, and filter to obtain titanium oxide and rare earth solution B.

[0037] (3) The rare earth feed solution B is extracted using an amine extractant. The introduced TBP dissolves the third phase. Sulfonated kerosene is used as the solvent. Under the conditions of an extraction temperature of 5-30℃, an extraction time of 0.5-15min, and an O / A volume ratio of 1:1-3, the rare earth ions are extracted and separated.

[0038] TBP acts as a co-solvent, allowing amine extractants to dissolve better, thereby improving the extraction effect.

[0039] Under the extraction conditions of this invention, the extraction rate can reach 85%-98.12%, which is highly efficient.

[0040] (4) The organic phase is stripped with a mixed solution of hydrochloric acid and chloride to obtain rare earth solution C; the concentration of hydrochloric acid is 0-1 mol / L, the concentration of chloride solution is 1-10 mol / L, the stripping temperature is 5-30℃ room temperature, the time is 0.5-5 min, the O / A volume ratio is 1:1-31:1.

[0041] This invention uses a mixed solution of hydrochloric acid and chloride (sodium chloride) for stripping, which can achieve a rare earth ion stripping rate of over 90% while controlling the iron ion stripping rate to below 5%.

[0042] (5) Precipitate the rare earth elements in the rare earth solution C using oxalic acid or oxalate, and calcine the precipitate at 500-1000℃ for 1-3 hours to obtain pure enriched rare earth oxides.

[0043] The method of this invention can recover valuable metal titanium while recovering rare earth elements, and the titanium recovery rate is over 60%.

[0044] The sedimentary rare earth ore used in this embodiment of the invention comes from the western Guizhou region; the composition and elemental analysis of the sedimentary rare earth ore are shown in Tables 1 and 2:

[0045] Table 1. Compositional Analysis of Sedimentary Rare Earth Ore

[0046]

[0047] Table 2. Rare Earth Element Analysis of Sedimentary Rare Earth Ore

[0048]

[0049] According to ICP-MS analysis, the total rare earth element content in each gram of sedimentary rare earth ore powder is 2790.2 μg. The most abundant rare earth element in the sample is Ce (1070 μg / g), followed by La (558 μg / g) and Nd (474 ​​μg / g), all of which are light rare earth elements. The content of heavy rare earth elements accounts for only 16.52% of the total rare earth element content.

[0050] The present invention will be further illustrated by the following examples.

[0051] Example 1

[0052] Step 1: Weigh 2g of sedimentary rare earth ore with more than 35% of particles passing through a 200-mesh sieve. Add sulfuric acid at a solid-liquid ratio of 1:1 and roast at 320℃ for 3 hours. After roasting, cool to room temperature and then leach in 20ml of aqueous solution for 3 hours at a solid-liquid volume ratio of 1:10 and a leaching temperature of 50℃ (the pH of the leaching solution during leaching is 1-2). After leaching, separate the solid and liquid to obtain slag and rare earth solution A. The rare earth element leaching rate is 81.3%, and the titanium leaching rate is 62.7%.

[0053] Step 2: Add ammonia to rare earth solution A to adjust the pH to 2, let it stand for 6 hours, and then filter to obtain titanium oxide and rare earth solution B.

[0054] Step 3: Extract the rare earth feed solution B with an amine extractant (N1923), introduce the co-solvent TBP, and use sulfonated kerosene as the solvent. Extraction conditions: TBP concentration (concentration in the organic phase, i.e., in the sulfonated kerosene) is 10% (v / v), N1923 concentration is 10% (v / v), O / A ratio is 1:1, ambient temperature (20℃), and extraction time is 4 min. The rare earth ions are extracted and separated, and the extraction rate of rare earth elements is 98.12%.

[0055] Step 4: The organic phase obtained after extraction in Step 3 was exfoliated using a mixed solution of hydrochloric acid and sodium chloride to obtain rare earth solution C; wherein the concentration of hydrochloric acid was 0.1 mol / L, the concentration of sodium chloride solution was 4.9 mol / L, the exfoliation temperature was room temperature, the time was 5 min, and the O / A volume ratio was 1:1. The exfoliation rate of iron ions was 3.92%.

[0056] Step 5: Precipitate the rare earth elements in rare earth solution C using sodium oxalate, and calcine the precipitate at 800℃ for 1 hour to obtain pure enriched rare earth oxides; wherein the mass ratio of sodium oxalate to the total mass of rare earth elements in the sedimentary rare earth ore is 1:1.

[0057] Example 2

[0058] Step 1: Weigh 2g of Guizhou sedimentary rare earth ore with more than 35% of particles passing through a 200-mesh sieve. Add sulfuric acid at a solid-liquid ratio of 1:1 and roast at 280℃ for 3 hours. After roasting, cool to room temperature and then leach in 20ml of aqueous solution for 3 hours at a solid-liquid volume ratio of 1:10 and a leaching temperature of 80℃ (pH of the leaching solution during leaching is 1-2). After leaching, separate the solid and liquid to obtain slag and rare earth solution A. The rare earth element leaching rate is 78.6%, and the titanium leaching rate is 60%.

[0059] Step 2: Add ammonia to rare earth solution A to adjust the pH to 2, let it stand for 5 hours, and then filter to obtain titanium oxide and rare earth solution B.

[0060] Step 3: Extract the rare earth feed solution B with an amine extractant (N1923), introduce the co-solvent TBP, and use sulfonated kerosene as the solvent. Extraction conditions: TBP concentration 10% (v / v), N1923 concentration 10% (v / v), O / A ratio 1:1, ambient temperature (40℃), extraction time: 2 min; achieve the extraction and separation of rare earth ions, with an extraction rate of 91% for rare earth elements.

[0061] Step 4: The organic phase obtained after extraction in Step 3 is exfoliated using a mixed solution of hydrochloric acid and sodium chloride to obtain rare earth solution C; wherein the concentration of hydrochloric acid is 0.1 mol / L, the concentration of sodium chloride solution is 4.9 mol / L, the exfoliation temperature is room temperature, the time is 5 min, and the O / A volume ratio is 1:1.

[0062] Step 5: Precipitate the rare earth elements in rare earth solution C using sodium oxalate, and calcine the precipitate at 800℃ for 1 hour to obtain pure enriched rare earth oxides; wherein the mass ratio of sodium oxalate to the total mass of rare earth elements in the sedimentary rare earth ore is 1:1.

[0063] Example 3

[0064] Step 1: Weigh 2g of Guizhou sedimentary rare earth ore with more than 35% of particles passing through a 200-mesh sieve. Add sulfuric acid at a solid-liquid ratio of 1:1 and roast at 240℃ for 3 hours. After roasting, cool to room temperature and then leach in 20ml of aqueous solution for 1 hour at a solid-liquid volume ratio of 1:10 and a leaching temperature of 50℃ (the pH of the leaching solution during leaching is 1-2). After leaching, separate the solid and liquid to obtain slag and rare earth solution A. The rare earth element leaching rate is 71.5%, and the titanium leaching rate is 57%.

[0065] Step 2: Add ammonia to rare earth solution A to adjust the pH to 2, let it stand for 8 hours, and then filter to obtain titanium oxide and rare earth solution B.

[0066] Step 3: Extract the rare earth feed solution B with an amine extractant (N1923), without introducing the co-solvent TBP, using sulfonated kerosene as the solvent. Extraction conditions: TBP concentration 0% (v / v), N1923 concentration 10% (v / v), O / A ratio 1:1, ambient temperature (20℃), extraction time: 4 min; achieve the extraction and separation of rare earth ions, with an extraction rate of 90% for rare earth elements.

[0067] Step 4: The organic phase obtained after extraction in Step 3 is exfoliated using a mixed solution of hydrochloric acid and sodium chloride to obtain rare earth solution C; wherein the concentration of hydrochloric acid is 0.1 mol / L, the concentration of sodium chloride solution is 4.9 mol / L, the exfoliation temperature is room temperature, the time is 5 min, and the O / A volume ratio is 1:1.

[0068] Step 5: Precipitate the rare earth elements in rare earth solution C using sodium oxalate, and calcine the precipitate at 800℃ for 1 hour to obtain pure enriched rare earth oxides; wherein the mass ratio of sodium oxalate to the total mass of rare earth elements in the sedimentary rare earth ore is 1:1.

[0069] Example 4

[0070] Step 1: Weigh 2g of Guizhou sedimentary rare earth ore with more than 35% of particles passing through a 200-mesh sieve. Add sulfuric acid at a solid-liquid ratio of 1:1 and roast at 200℃ for 3 hours. After roasting, cool to room temperature and then leach in 20ml of aqueous solution for 5 hours at a solid-liquid volume ratio of 1:10 and a leaching temperature of 50℃ (the pH of the leaching solution during leaching is 1-2). After leaching, separate the solid and liquid to obtain slag and rare earth solution A. The rare earth element leaching rate is 72.8%, and the titanium leaching rate is 59%.

[0071] Step 2: Add ammonia to rare earth solution A to adjust the pH to 2, let it stand for 6 hours, and then filter to obtain titanium oxide and rare earth solution B.

[0072] Step 3: Extract the rare earth feed solution B with an amine extractant (N1923), introduce the co-solvent TBP, and use sulfonated kerosene as the solvent. Extraction conditions: TBP concentration 10% (v / v), N1923 concentration 10% (v / v), O / A ratio 1:1, ambient temperature (20℃), extraction time: 2 min; achieve the extraction and separation of rare earth ions, with an extraction rate of 87% for rare earth elements.

[0073] Step 4: The organic phase obtained after extraction in Step 3 is exfoliated using a mixed solution of hydrochloric acid and sodium chloride to obtain rare earth solution C; wherein the concentration of hydrochloric acid is 0.1 mol / L, the concentration of sodium chloride solution is 4.9 mol / L, the exfoliation temperature is room temperature, the time is 5 min, and the O / A volume ratio is 1:1.

[0074] Step 5: Precipitate the rare earth elements in rare earth solution C using sodium oxalate, and calcine the precipitate at 800℃ for 1 hour to obtain pure enriched rare earth oxides; wherein the mass ratio of sodium oxalate to the total mass of rare earth elements in the sedimentary rare earth ore is 1:1.

[0075] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for separating and extracting rare earth elements and titanium from sedimentary rare earth ores, characterized in that, Includes the following steps: The sedimentary rare earth ore is mixed with acid and roasted, then added to water for leaching. After solid-liquid separation, slag and rare earth liquid A are obtained. After allowing the rare earth solution A to stand, it was filtered to obtain titanium oxide and rare earth solution B; The rare earth feed solution B was extracted using an amine extractant to obtain an organic phase; The organic phase is stripped and then precipitated to obtain a precipitate; the precipitate is calcined to obtain rare earth oxides. The liquid-to-solid volume ratio of the sedimentary rare earth ore to the acid is 0.5-2.5:1; the acid is sulfuric acid; the roasting temperature is 200-320℃ and the time is 1-6 hours. The liquid-to-solid volume ratio during leaching is 5-25:1; the leaching temperature is 20-100℃, and the leaching time is 1-5 hours. The settling time is 5-10 hours; before settling, the step of adding ammonia water to adjust the pH of the rare earth solution A to 2 is also included. The solvent used for extraction is sulfonated kerosene; the extraction conditions are: amine extractant volume concentration of 0-10% and not 0, O / A ratio of 1:(1-3), temperature of room temperature, and extraction time of 1-14 min.

2. The method for separating and extracting rare earth elements and titanium from sedimentary rare earth ores according to claim 1, characterized in that, The amine extractant is at least one of N1923, dodecylamine, octylamine, and isooctylamine.

3. The method for separating and extracting rare earth elements and titanium from sedimentary rare earth ores according to claim 1, characterized in that, Tributyl phosphate is added during the extraction process; the volume concentration of tributyl phosphate during extraction is 0-10% and not 0.

4. The method for separating and extracting rare earth elements and titanium from sedimentary rare earth ores according to claim 1, characterized in that, The stripping is performed using a mixed solution of hydrochloric acid and chloride; the concentration of hydrochloric acid in the mixed solution is 0-1 mol / L, and not 0; the concentration of chloride in the mixed solution is 1-10 mol / L; the stripping temperature is room temperature, and the time is 0.5-60 min; during the stripping, the O / A volume ratio is 1:(1-3).

5. The method for separating and extracting rare earth elements and titanium from sedimentary rare earth ores according to claim 1, characterized in that, Oxalic acid or oxalate is used for precipitation; the calcination temperature is 500-1000℃ and the time is 1-3h.

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