CN100584967C - Method for fully separating high-purity rare earth oxides from sulfuric acid intensified roasting rare earth ores - Google Patents

Abstract

The invention discloses a method for completely separating high-purity rare earth oxides from sulfuric acid-intensified roasting rare earth ores. The combined separation technology of ultrasonic leaching-ammonia neutralization purification-ultrasonic extraction-electrochemical valence change-chemical treatment is used to separate high-purity rare earth oxides. Pure Ce ₂ O ₃ , La ₂ O ₃ , Pr ₂ O ₃ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₄ O ₇ , Dy ₂ O ₃ and Y ₂ O ₃ . Apply ultrasonic-extraction coupling technology to improve the dispersibility of the liquid-liquid extraction process, enhance the extraction rate and efficiency; use electrochemical oxidation-reduction technology to control the valence state of rare earth elements, in the electrochemical reactor, the acidic rare earth solution Ce ³⁺ is oxidized to Ce ⁴⁺ , and trivalent europium Eu ³⁺ is reduced to divalent europium Eu ²⁺ to separate it from other trivalent rare earths; ultrasonic technology is used to strengthen the chemical treatment process, and the extraction rate is fast, the efficiency is high, and the separation The yield is high, the material can be recycled, and the separation method is safe and reliable. It is an ideal clean and complete separation scheme, and it is also an ideal separation scheme for comprehensive economic benefits.

Description

Method for fully separating high-purity rare earth oxides from sulfuric acid intensified roasting rare earth ores

Technical field:

The invention relates to the separation of rare earth ores strengthened by sulfuric acid roasting, and belongs to the field of hydrometallurgy.

Background technique:

Sulfuric acid roasting method to decompose rare earth ore is to mix rare earth ore (bastnaesite or a mixture of bastnaesite and monazite) with concentrated sulfuric acid and then roast continuously in a rotary kiln at a temperature of 300-800°C. Rare earth and Thorium and other elements generate soluble sulfate, fluorite is transformed into insoluble sulfur concentrated calcium and volatile gas hydrogen fluoride or silicon fluoride, iron, manganese and other minerals are also decomposed to varying degrees and transformed into sulfate. Rare earth ores can be directly leached with water after being roasted with sulfuric acid. The current industrial production method for leaching rare earths is to leaching the materials roasted with sulfuric acid with water. Since the water leaching solution contains impurities such as iron, phosphorus, manganese, and thorium, it must be purified. The classic purification method is to add sodium chloride and sodium sulfate to the water immersion solution, so that the rare earth is precipitated in the form of rare earth sodium sulfate double salt and separated from impurities. The precipitated rare earth sodium sulfate double salt is washed with 20% to 30% % caustic soda aqueous solution to convert it into rare earth hydroxides, dissolve the rare earth hydroxides with hydrochloric acid to form a rare earth chloride solution, and then further group the rare earth elements and separate and refine them to obtain rare earth oxide products or rare earth rich Collection.

The methods for separating rare earth elements include double salt precipitation method and fractional distillation extraction method, but the extraction method is mainly used at present. Using P204 or P507 as the extraction agent and kerosene as the diluent, the rare earth mixture can be extracted into light-heavy rare earth groups in an acidic system, three groups of light, medium and heavy rare earths, and four groups of light, medium light, medium heavy and heavy rare earths Group. The principle of grouping is to control a certain acidity and extraction rate of the water phase. Under different acidities, the complexing ability of P204 or P507 and rare earth elements is different. Controlling a certain acidity can make it have a certain extraction rate and stripping rate. Elements can then be grouped by predetermined boundaries.

The boundaries and acidity control ranges of typical three-component groups are as follows: use P204 as the extraction agent, samarium-neodymium grouping: the acidity of the lotion is 0.5-1.2 mol/L of hydrochloric acid, and the separation coefficient β _Sm/Nd is 5-12; Gadolinium is grouped, the acidity of the lotion is 1.5-2.0 mol/L of hydrochloric acid, and the separation coefficient β _Gd/Sm is 3-3.5; Gadolinium-terbium is grouped, the acidity of the lotion is 2.0 mol/L of hydrochloric acid, and the separation coefficient β _Tb/Gd is 5~6. The specific fractionation extraction grouping process of rare earth elements is that the rare earth chloride concentration in the feed liquid is 1-1.2mol/L, the acidity of the feed liquid is pH=4-4.5, and the composition of the organic phase is P204 kerosene solution of 1.0mol/L. The acidity of the solution is hydrochloric acid concentration 0.8mol/L, and neodymium-samarium grouping is carried out. The raffinate containing rare earth elements such as lanthanum and neodymium is neutralized with ammonia and then concentrated and crystallized to form rare earth chlorides. The organic phase loaded with rare earth elements such as gadolinium and dysprosium is then subjected to group extraction of gadolinium-dysprosium. The concentration of the extractant remains the same. It is 1.0 mol/L P204 kerosene solution, the acidity of the washing solution is 2.0 mol/L hydrochloric acid, and the aqueous phase after extraction is precipitated with sodium carbonate to form medium rare earth carbonate. The organic phase generated after extraction is back-extracted with 5.0 mol/L hydrochloric acid to generate yttrium and heavy rare earth chloride products.

Compared with the double salt precipitation method, the process of using P204 fractional distillation to extract and group rare earths has many advantages. The fractional distillation, extraction and grouping method simplifies the process and realizes continuous production. , medium and heavy rare earth products, which expands the comprehensive utilization of rare earths, and can be directly connected with the next fractional distillation extraction process for further separation and purification, and this process also reduces the "three wastes".

Japanese patent document (Japanese Patent Laid-Open No. 54-93672) introduces a process for extracting and separating rare earth elements using P507 as an extractant. In order to speed up the grouping, a phase separation agent needs to be added to prevent emulsification and the formation of a third phase. The advantage of using P507 as the extraction agent is that the acidity of stripping is low, it is easy to carry out stripping, and the separation coefficient between some rare earth elements is larger than that of P204.

Chinese patent (CN 1009332B) has introduced Baotou Metallurgical Institute etc. to use 2-ethylhexyl phosphoric acid mono-2-ethylhexyl (hereinafter referred to as P507) to separate the technological process of rare earth element. The process uses rare earth chloride as raw material, the concentration of rare earth chloride in the feed liquid is 240-250g/L, the pH of the feed liquid is 2-3, and the organic phase is composed of 50% P507-50% kerosene (volume ratio), The acidity of the lotion is 1.2-1.3mol/L hydrochloric acid. Firstly, neodymium-samarium is grouped, and then P507 is used as the extraction agent to sequentially separate the groups of praseodymium-neodymium, cerium-praseodymium, lanthanum-cerium, samarium-europium, and gadolinium-terbium. Products such as neodymium oxide, praseodymium oxide, cerium oxide, lanthanum oxide, samarium oxide and heavy rare earth oxides are obtained.

Chinese patent (CN 1009332B) introduces the Beijing Nonferrous Metals Research Institute's treatment of Baotou rare earth ore sulfuric acid intensified roasting process. In the enhanced roasting process, by increasing the roasting temperature and prolonging the roasting time, impurities such as phosphorus, thorium, and iron in the ore form slightly soluble phosphate and other substances, and then the roasted material is leached with water. The acidity of the water immersion solution is 0.05-0.15mol/L sulfuric acid, and the water immersion solution is neutralized with calcium oxide or calcium carbonate. The other forms are further precipitated and removed to obtain a pure rare earth sulfuric acid solution completely separated from impurities. If P204 or P507 is used as the extraction agent to connect with the hydrochloric acid system fractionation extraction and separation of rare earth elements, it is necessary to transform the rare earth sulfuric acid solution into rare earth chlorides through a transformation process. The transformation method is at a pH of 4-5. In the sulfuric acid solution, the fatty acid or naphthenic acid containing 5 to 9 carbons is used as the extraction agent, kerosene is used as the diluent for extraction, and then 5.0mol/L hydrochloric acid is used as the stripping agent for stripping to generate rare earth chlorides.

Chinese patent (CN 1009332B) introduces the process and method of extracting and separating rare earth elements from sulfuric acid system in view of the problems existing in the previous separation process. The process and method is to neutralize and purify the water immersion solution obtained by roasting rare earth ore with sulfuric acid to obtain a pure rare earth sulfate solution, and then use P204 kerosene solution for fractional distillation and extraction, and the concentration of mixed rare earth in the feed solution is less than 50g /L rare earth oxide. The concentration of extractant is less than 2mol/L. The invention process can produce samarium, europium, gadolinium and other medium-heavy rare earth enrichment (Eu ₂ O ₃ 11%, Sm ₂ O ₃ -50%, Eu ₂ O ₃ recovery rate is about 99%, crude neodymium oxide (Nd ₂ O ₃ /RE ₂ O ₃ >85%) and products such as lanthanum cerium chloride. Crude neodymium chloride can be used as raw material for high-performance magnet NdFeB. The cost of the product.

From the current literature, it can be found that my country's rare earth separation technology, especially the extraction and separation technology of rare earth, has reached the world's leading level. However, rare earths in rare earth ores are generally in the form of carbonates, fluorides, phosphates, oxides or silicates that are insoluble in water. Rare earths must be converted into water-soluble or inorganic acid-soluble compounds through various chemical changes, and various mixed rare earth compounds can be made into various mixed rare earth compounds through processes such as dissolution, separation, purification, and concentration, as products or raw materials for separating single rare earths. It is relatively complicated and difficult to separate and extract a single pure rare earth element from the mixed rare earth compound obtained after the decomposition of rare earth ore. There are two main reasons for this: first, the physical and chemical properties of lanthanide elements are very similar, and the radii of most rare earth ions are between adjacent two elements, and they are all in a stable trivalent state in aqueous solution. Due to the protection of hydrates, their chemical properties are very similar, and separation and purification are extremely difficult; second, the mixed rare earth compounds obtained after the decomposition of rare earth ores have more associated impurity elements (such as uranium, thorium, niobium, tantalum , titanium, zirconium, iron, calcium, silicon, fluorine, phosphorus, etc.).

Therefore, in the technological process of separating rare earth elements, not only the separation between these dozens of rare earth elements with extremely similar chemical properties must be considered, but also the separation between rare earth elements and accompanying impurity elements must be considered. The wet production process separation methods currently used in rare earth production mainly include: (1) stepwise method (fractional crystallization method, fractional precipitation method and redox method); (2) ion exchange method; (3) solvent extraction method.

Hydrometallurgy is a method of chemical metallurgy, and the whole process is mostly in solution and solvent, such as the decomposition of rare earth ores, the separation and extraction of rare earth oxides, rare earth compounds, and single rare earth metals, using precipitation, crystallization, redox, and solvent extraction. , ion exchange and other chemical separation processes. Now the more common application is organic solvent extraction, which is a common process for industrial separation of high-purity single rare earth elements. Although the process of hydrometallurgy is complicated, the products are of high purity and the finished products are widely used.

At present, the mainstream of rare earth separation is extraction method, ion exchange method and fractional crystallization method. The first two methods are discontinuous in the process, the cost is high, and the purity of the rare earth elements extracted is also low, which cannot be adapted to large-scale industrial production. Extraction is a method of separating substances by using the characteristics of different solubility of substances in different solvents. my country has reached a very high level in the research of extraction theory, the synthesis and application of new extractants, and the extraction process for the separation of rare earth elements. Compared with separation methods such as fractional precipitation, fractional crystallization, and ion exchange, the solvent extraction method has a series of advantages such as good separation effect, large production capacity, convenient rapid continuous production, and easy realization of automatic control. Therefore, it has gradually become a large-scale separation method. The main method of rare earth.

Solvent extraction is an important separation method in chemical industry. It has the advantages of good selectivity, fast mass transfer, high separation efficiency, large processing capacity, continuous operation, and simple equipment. It has become the main method for single rare earth production at home and abroad. Rare earth smelters in my country basically adopt a single rare earth separation process with P504, P507 and naphthenic acid extraction as the main technology, combined with P507 extraction resin chromatography, ion exchange chromatography, redox and other separation technologies, can produce a purity of 4 ~5N single rare earth product. In the separation process, we have a batch of unique and advanced extraction processes. It can be considered that the level of rarefied separation technology in our country ranks among the top in the world. At present, the separation equipment of the solvent extraction method for industrial application includes mixing and settling tanks, centrifugal extractors, etc. The extraction agents used for the purification of rare earths include: cationic extractants such as P204 and P507 represented by acidic phosphate esters; anion exchange agents represented by amines Liquid N1923; and neutral phosphates such as TBP and P350 are representative solvent extractants. The viscosity and specific gravity of these extractants are very high, and they are not easy to separate from water. It is usually used after diluting it with a solvent such as kerosene. The extraction process can generally be divided into three main stages: extraction, washing, and stripping.

However, as an industrial separation technology, extraction has passed the test of production practice, and there are still many chemical process and engineering problems that need to be further studied and solved. There are also many problems in the existing rare earth extraction and separation production process, such as unstable quality, high cost, high energy consumption, large amount of "three wastes" treatment, and "poisoning" of the extraction agent. This puts forward more and higher requirements on the technical methods and equipment of extraction and separation. There must be a new efficient and simple rare earth separation process (including major improvements to the existing industrial production process) to meet the requirements of high-tech materials for a single The need for high-purity or ultra-high-purity rare earth products. The main issues are:

(1) Problems with the extraction system

The key to optimizing the selection of the extraction system is the extractant. The average separation coefficient of P507 (2-ethylhexyl phosphate mono-2-ethylhexyl ester) to rare earth elements (β is 2.2 to 2.4) is better than that of P204 (2-ethylhexyl phosphate diester), which is an effective method for extracting and separating rare earth elements. extractant, but also has the following deficiencies:

① Heavy rare earth element stripping acid concentration is high, especially scandium is difficult to strip completely;

② The separation coefficient (β) of some element pairs is small, such as the β value of Nd/Pr, Gd/Eu, Er/Y, Lu/Yb, etc. is between 1.4 and 1.8;

③In hydrochloric acid or sulfuric acid medium, the extraction rate of heavy rare earth ions is slow, and it takes a long time to reach extraction equilibrium, which will affect the improvement of productivity and economic benefits.

(2) Problems with extraction equipment

At present, the main equipment for extraction and separation is the mixing-settling tank. The mixing-settling tank has the characteristics of strong adaptability to the change of relative flow rate and easy operation. It is the extraction equipment commonly used in the production of rare earths in my country. In industrial production, in order to ensure high stage efficiency of the tank, it is often necessary to increase the residence time of the phase in the mixing chamber and increase the clarification time, resulting in an increase in the total volume of the tank. Normally, the volume ratio of the clarification chamber to the mixing chamber is 2.5-3.0. This is mainly because the particles of the dispersed phase are small and difficult to aggregate and separate phases. In order to improve the separation efficiency and reduce the effective volume of the tank, domestic and foreign scholars have made many improvements to the design of the mixing and clarifying extractor in recent years, such as the study of separating the mixing chamber into multiple compartments, and the electrostatic coagulation method can accelerate the phase separation process.

Therefore, how to speed up the extraction rate of the industrial extraction system is one of the key issues to improve the production capacity of the factory and reduce the cost.

(3) The connection between processes and the "three wastes" problem

The rare earth production process is an optimized combination of different separation processes. Among them are the connection between the extraction process and the connection between the extraction process and other subsequent processes. In addition to the connection of the raffinate water phase as the feed liquid, the key issue is the process connection of the organic phase outlet components. Because the rare earth concentration of the raffinate and stripping liquid is low and the acidity is high, it is generally used after being neutralized by alkali and concentrated by heating. This method not only consumes a lot of energy, a large amount of residual acid cannot be recovered, the operation is complicated, the equipment loss is large, and it pollutes the environment and produces new "three wastes". Therefore, it is important to study continuous and simple material-liquid concentration and acid removal processes The key to the connection of the separation process, the use of precipitation and stripping is one of the effective ways.

Therefore, it is an urgent problem to be solved in the rare earth extraction process to improve the recycling rate of rare earths, reduce consumption and improve production efficiency.

Invention content:

The purpose of the present invention is to propose a method for fully separating high-purity rare earth oxides from sulfuric acid intensified roasting rare earth ores, using ultrasonic leaching-ammonia neutralization purification-ultrasonic extraction-electrochemical valence change-chemical treatment combined separation technology to separate high-purity Ce ₂ O ₃ , La ₂ O ₃ , Pr ₂ O ₃ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₄ O ₇ , Dy ₂ O ₃ are Y ₂ O ₃ .

All kinds of rare earth products separated by the present invention have the advantages of high quality and high stability, strong competitiveness and good economic benefits.

The method for fully separating high-purity rare earth oxides from sulfuric acid-intensified roasting rare earth ores according to the present invention is characterized in that: ultrasonic leaching-ammonia neutralization purification-ultrasonic extraction-electrochemical valence change-chemical treatment combined separation technology is used to completely separate High-purity rare earth oxides Ce ₂ O ₃ , La ₂ O ₃ , Pr ₂ O ₃ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₄ O ₇ , Dy ₂ O ₃ and Y ₂ O ₃ , comprising the following process steps:

(1) Ultrasonic leaching: In the ultrasonic leaching device, water or sulfuric acid aqueous solution containing rare earth in the process is used as the leaching agent for leaching operation, and the rare earth in the rare earth ore roasted by sulfuric acid is leached, and after solid-liquid separation, Obtain rare earth sulfate solution;

(2) Neutralization and purification: in the stirring neutralization purification device, neutralize and purify with ammonia or alkaline earth metal oxides, and remove non-rare earth element impurities through solid-liquid separation to obtain pure rare earth sulfate solution;

(3) Ultrasonic extraction grouping: In the ultrasonic extraction device, P204 is used as the extraction agent and kerosene is used as the diluent for extraction grouping. The aqueous phase is the light rare earth sulfate enrichment; the organic phase is the heavy rare earth sulfate enrichment; The phase is removed for further separation treatment, and the organic phase enters the step (8) for further separation treatment;

(4) Electrochemical oxidation: The aqueous phase sulfate-rich solution obtained in the previous step enters the anode chamber of the electrochemical reactor. Under acidic conditions, Ce ³⁺ in the rare earth solution is oxidized to Ce ⁴⁺ , and simultaneously produces Ce(SO ₄ ) ₂ is precipitated, and after solid-liquid separation, the liquid phase enters the next step of treatment; the solid phase is crude cerium sulfate, and the crude cerium sulfate is washed, dissolved, purified, precipitated and burned to obtain cerium oxide product;

(5) Electrochemical reduction: the non-cerium light rare earth enrichment solution obtained through solid-liquid separation in the previous step enters the cathode chamber of the electrochemical reactor in the previous step. Under acidic conditions, the trivalent europium in the rare earth solution Eu ³ After ⁺ is reduced to divalent europium Eu ²⁺ , europium sulfate EuSO ₄ precipitates, and after solid-liquid separation, it is separated from other trivalent rare earths, and the liquid phase enters the next step for further separation and purification; the solid phase is crude europium sulfate, Europium sulfate crude product is washed, dissolved, purified, precipitated and burned to obtain europium oxide product;

(6) Ultrasonic extraction and fractionation grouping: the liquid phase after solid-liquid separation in the previous step is non-cerium and europium light rare earth solution, this solution enters the ultrasonic extraction grouping device, and the sulfuric acid with _La2O3 content of _17-28g /L The raffinate is the feed liquid, adjust its pH to 1-5, kerosene is the diluent for extraction and grouping, the P204 content in the organic phase is 1.0-1.5mol/L, and the volume ratio between the organic phase and the aqueous phase is 1-3 : 1, carry out countercurrent extraction, obtain the aqueous phase to be the lanthanum enrichment, and the lanthanum enrichment obtains the lanthanum oxide product through washing, dissolving, purifying, precipitating and burning;

(7) Ultrasonic fractionation extraction and separation: the organic phase extracted in the previous step is praseodymium-neodymium enrichment and gadolinium-terbium enrichment, after further ultrasonic fractionation extraction and separation, refining, washing, dissolving, purification, precipitation and burning Obtain praseodymium oxide, neodymium oxide, gadolinium oxide and terbium oxide;

(8) Ultrasonic fractionation extraction grouping: the heavy rare earth sulfate enrichment solution obtained in step (3) ultrasonic extraction grouping is used as the raw material liquid, and the organic phase containing heavy rare earth elements in samarium, gadolinium and terbium in the extract is extracted by solvent Transformation, using hydrochloric acid as the stripping solution, converting the rare earth sulfuric acid solution into a rare earth hydrochloric acid solution, removing Ca ²⁺ , Mg ²⁺ and Fe ²⁺ impurities from the raffinate during the extraction transformation process, and controlling the stripping agent concentration And the flow rate makes the rare earth enriched. In the ultrasonic fractionation extraction grouping device, the obtained rare earth hydrochloric acid solution is used as the raw material liquid; the mixture of 0.2-0.7mol/L P507 ammonium salt, 0.8-1.5mol/L P507 and kerosene For extracting the organic phase; the concentration of hydrochloric acid in the washing liquid is 1.1-3.6mol/L; its volume flow ratio is extracting the organic phase: raw material liquid: washing liquid=0.85-3.5: 1: 0.12-0.70, in this fractionation extraction group separation process , the molar concentration of rare earth in the raffinate phase is 0.1-1.0mol/L, and the gadolinium-terbium enrichment and terbium-dysprosium enrichment are obtained. Further separate and refine to produce heavy rare earth oxidation products in gadolinium oxide, terbium oxide and enriched dysprosium oxide.

In the present invention, the process conditions of the extraction operation are: the solid-liquid ratio is 1000g:(8-30)L, the operating temperature is 5-50°C, the ultrasonic action intensity is 0.2-20.0W/cm ² , and the ultrasonic frequency is 19-80kHz.

In the present invention, the ultrasonic generating device is any one of a probe type ultrasonic generator, a vibrator type ultrasonic generator, and a vibrating plate type ultrasonic generator.

In the present invention, in the ultrasound-enhanced rare earth leaching-extraction process, the ultrasonic leaching-extraction equipment is a kettle-type extraction equipment or a mixing-clarification extraction equipment or a tubular extraction equipment with a heat exchange device and a stirring device Equipment; or continuous tank extraction equipment or mixing-clarification extraction equipment or tubular extraction equipment without heat exchange devices and stirring devices.

In the present invention, in the ultrasonically enhanced rare earth extraction process, the ultrasonic extraction is simple extraction or fractional extraction or group extraction; in the ultrasonic fractional extraction process, a multi-component two-outlet process or a multi-component multi-outlet fractionation cascade extraction process .

In the present invention, when fractionation and group separation are carried out, the content of rare earth cerium oxide in the feed liquid is 30-46g/L, the acidity of the feed liquid is pH=4 to 0.15mol/L sulfuric acid, and the content of P204 in the organic phase is 0.5-46g/L. 1.5mol/L, the concentration of sulfuric acid in the washing solution is 0.4-0.6mol/L.

In the present invention, the electrochemical reactor is an ordinary planar electrochemical reactor or a three-dimensional electrochemical reactor; the anode chamber and the cathode chamber of the electrochemical reactor are separated by an isolation film; in the anode chamber of the electrochemical reactor In the cathode chamber, the oxidation reaction of Ce ³⁺ is carried out, and in the cathode chamber, the reduction reaction of Eu ³⁺ is carried out, or two electrochemical reactors are used to carry out the oxidation of Ce ³⁺ and the reduction of Eu ³⁺ respectively.

In the present invention, ammonia is added to the refined pure component rare earth solution to produce hydroxide crystals and precipitate out. After solid-liquid separation, the hydroxide precipitate is analyzed. If the purity does not meet the requirements of the product, repeat the above Separation process until the purity requirements are met; then use hydrochloric acid to dissolve the hydroxide precipitate to prepare a refined rare earth hydrochloride solution; in the refined rare earth hydrochloride, use activated carbon or resin adsorption to further remove impurities; add carbonic acid to the refined rare earth hydrochloride solution Ammonium hydrogen or ammonium carbonate, the resulting precipitate is separated in a solid-liquid separator, and the separated liquid phase is further separated to obtain a single-component rare earth product; the solid phase product is dried at 25-600°C to obtain a rare earth carbonate product, rare earth carbonate The product is burned at 600-1000°C to obtain high-purity rare earth oxide products; in order to improve the separation and refining process and the quality of rare earth products, ultrasonic In the strengthening process, the technological conditions of the ultrasonic strengthening process are as follows: the operating temperature is 25-45° C., the ultrasonic action intensity is 2.0-5.0 W/cm ² , and the ultrasonic frequency is 19-25 kHz.

In the process of continuous separation of rare earth elements, the extractant is regenerated and recycled. In the process flow, the utilization of water is returned to the unit process that matches the process conditions for recycling. Under the condition of meeting the production process , so that the concentration of rare earth elements in the feed liquid is as high as possible, and the excess water is used to increase the concentration of rare earth elements during the separation process by vacuum multi-effect evaporation concentration method, and at the same time solve the problem of wastewater treatment and realize process clean production.

The absolute pressure of the vacuum multi-effect evaporation and concentration operation of the feed liquid is 0.001-0.008 MPa.

The present invention is the joint application of following three kinds of methods and technology:

(1) Liquid-solid ultrasonic leaching and liquid-liquid ultrasonic extraction technology

The liquid-solid leaching and liquid-liquid extraction processes are enhanced with ultrasound. In the ultrasonic leaching device, the rare earth in the rare earth ore that has been intensively roasted by sulfuric acid is leached; after solid-liquid separation, the rare earth sulfate solution mixture is obtained, and the rare earth sulfate solution mixture is grouped and separated by ultrasonic extraction. After fractional distillation, extraction and group separation, the aqueous phase is a light rare earth (cerium group) sulfate enrichment; the organic phase is a heavy rare earth (yttrium group) sulfate enrichment.

Solvent extraction is an important chemical engineering separation method, which has the advantages of high extraction and separation efficiency, convenient continuous operation, and large production capacity. Over the years, my country has done a lot of work on rare earth production technology and theoretical research. In view of the characteristics of rare earth raw materials with many components and large changes in composition, the equivalent components, effective separation coefficient model and Methods and technologies for optimizing cascade extraction process parameters such as fuzzy extraction and separation technology have enriched and developed cascade extraction theory. However, the current rare earth extraction and separation process mainly has the following problems:

①Liquid-liquid extraction mixing problem: In the liquid-liquid extraction mixing process, the mixing and dispersion are insufficient, the mass transfer rate of the liquid-liquid phase is low, and it is difficult to quickly achieve microscopic mixing. Therefore, the rare earth extraction mixing process is slow and inefficient.

②The problem of liquid-liquid stratification (that is, clarification) after liquid-liquid extraction mixing: In the extraction and separation process of rare earths, mixing is the basic condition for the redistribution of the extract, and clarification is a necessary process for extraction and distribution. If the mixing is sufficient, although the distribution ability of the extraction is fully exerted, the particles of the dispersed phase are small, and it is difficult to gather and separate the phases, but it brings about the problem of poor separation effect in the liquid-liquid layering process after the liquid-liquid extraction is mixed. Therefore, in the traditional rare earth extraction and separation process, mixing and clarification are a pair of contradictions. How to strengthen the rare earth extraction process, solve the contradiction between mixing and clarification in the rare earth extraction process, effectively control the particle size, particle size distribution and other physical properties of rare earth, and develop efficient extraction technology has very important application value, is the development of efficient and economical The key to rare earth extraction technology. Data reports and our research have shown that ultrasound is an effective means of enhancing chemical engineering processes. Since the 1950s, some researchers in the United States, the former Soviet Union and other countries have reported the application of ultrasound in chemical engineering, which has aroused great interest in the academic and industrial circles of chemical engineering and process engineering. The application of ultrasound has expanded from the previous field of physics to the field of chemistry and chemical engineering. At present, the application research of ultrasound in chemical engineering processes such as extraction, crystallization, emulsification, precipitation and environmental treatment has attracted people's attention day by day.

The feature of the present invention is that the extraction and separation of rare earth system, which has a major industrial application background, is selected as the research system, and the technology of ultrasonic and extraction coupling separation of rare earth is adopted to achieve a breakthrough in the key technology of the extraction and separation of rare earth process. Its innovation is to apply the relevant effect of ultrasonic cavitation to improve the dispersion of the liquid-liquid extraction process, increase the extraction mass transfer rate and the clarification and separation process after extraction, and use physical technology to fundamentally solve the outstanding contradictions of rare earth extraction and separation. , improve the efficiency of rare earth extraction and the production capacity of extraction equipment, reduce process energy consumption, and promote the leapfrog development of rare earth extraction and separation technology in my country.

Ultrasound can strengthen the extraction (leaching) process, and its role is mainly manifested in: the cavitation of ultrasound can produce liquid-liquid dispersion, enhance mass transfer and demulsification, etc. The influence of ultrasound on the extraction process is mainly due to the cavitation effect of ultrasound and its subsequent microjet action. Theories and practices of ultrasound in surface cleaning, catalyst preparation, emulsion preparation, and enhanced electrochemistry have been used for reference, but the coupling of ultrasound and extraction process to the extraction (leaching) separation of rare earths has not been reported at home and abroad.

(2) Electrochemical oxidation-reduction technology: realize the price change of rare earth elements through electrochemical methods. The electron layer structure of lanthanide atoms is [Xe]4f ^0-14 5d ^0-1 6s ² , when two 6s and one 5d or 4f electrons are lost, the most common Lu ³⁺ is formed, among which La ³⁺ , Gd The 4f sublayers of ³⁺ and Lu ³⁺ are fully empty, half full or fully full, respectively. According to Hund's rule, these states are the most stable, so the +3 valence of these three elements is the most stable. The Lu ³⁺ located on both sides of them have a tendency to gain or lose electrons to reach or approach the above stable state. This results in a change in the valence of the genium elements next to La, Gd, and Lu. For example, Ce ³⁺ , Pr ³⁺ , Tb ³⁺ and Dy ³⁺ form a four-valence, while Sm ³⁺ , Eu ³⁺ , Tm ³⁺ , and Yb ³⁺ form a two-valence. The separation efficiency is much higher than that of general ion exchange and solvent extraction separation by utilizing the variable price property of rare earths. Apply electrochemical oxidation-reduction technology to oxidize Ce ³⁺ in the acidic rare earth solution to Ce ⁴⁺ , and reduce high-valent europium Eu ³⁺ to low-valent europium Eu ²⁺ , thereby separating it from other trivalent rare earths. The separation efficiency is much higher than that of general ion exchange and solvent extraction separation by utilizing the variable price property of rare earths.

(3) Chemical treatment: It is used for the dissolution, washing, purification of rare earth ore and the precipitation and burning of the pure solution of the product. At the same time, ultrasonic technology is used to strengthen the chemical treatment process. The principle of ultrasonic enhanced chemical treatment is to use the cavitation effect, mechanical effect and thermal effect generated when ultrasonic waves propagate in the medium to strengthen the dispersion of the solid phase in the liquid phase, the surface renewal of the solid-liquid interface, and the material transfer between solid and liquid. Thereby enhancing the extraction process and improving the rate and efficiency of the rare earth separation process.

Advantages of the present invention:

The advantages of the present invention are:

(1) The process of the present invention uses sulfuric acid intensified roasting method to smelt rare earth ore as raw material, and applies ultrasonic leaching-ammonia neutralization purification-ultrasonic extraction-electrochemical valence-chemical treatment combined separation technology, which is a process directly linked to the process of separating rare earth elements process.

(2) The process of the present invention is provided with neutralization and purification with ammonia or alkaline earth metal oxides before separating the rare earth elements, and through solid-liquid separation, the non-rare earth element impurities are removed to obtain a pure sulfuric acid rare earth solution, which is neutralized and purified with ammonia, It prevents the formation of rare earth double salt precipitation and calcium sulfate slag, and improves the recovery rate of rare earth in the purification process compared with the neutralization and purification of calcium oxide or calcium carbonate powder, and the amount of slag is doubled.

(3) Since there is no interference from silicon, fluorine, phosphorus and trace coagulants during the extraction process, emulsification does not occur, which ensures the normal progress of the extraction process and the subsequent separation process.

(4) In the sulfuric acid system, P204 is used as the extractant, and kerosene is used as the diluent for fractional distillation and extraction to separate rare earth elements in groups. The separation coefficient β between some rare earth elements in the hydrochloric acid system is higher than that at pH 1-4.

(5) Since in the sulfuric acid solution of rare earth elements, when P204 is used as the extraction agent for extraction, because the gadolinium-terbium separation coefficient β value is relatively large, it is easy to group and separate between gadolinium-terbium, so firstly the gadolinium-terbium is separated. Separation of groups by ultrasonic extraction.

(6) Ultrasonic extraction: Apply ultrasonic-extraction coupling technology to improve the dispersibility of the liquid-liquid extraction process, increase the extraction mass transfer rate and the clarification process after extraction, and apply physical technology to fundamentally solve the mixing and clarification existing in the rare earth extraction process The contradiction of the process enhances the speed and efficiency of the extraction process.

(7) Electrochemical valence change: The valence state of rare earth elements is controlled by electrochemical oxidation-reduction technology. In the same electrochemical reactor, Ce ³⁺ is oxidized to Ce ⁴⁺ in acidic rare earth solution at the same time, and the trivalent Europium Eu ³⁺ is reduced to divalent europium Eu ²⁺ to separate it from trivalent rare earth, which further improves the separation rate and efficiency, improves the utilization efficiency of the electrochemical reactor, reduces energy consumption, and protects environment. Applying electrochemical oxidation-reduction technology to control the valence state of rare earth elements can reduce the consumption of chemical materials, reduce pollution, improve extraction selectivity, reduce the separation load of rare earth and non-rare earth impurities, reduce the transformation of rare earth forms and valence states, and make the reaction conditions tend to This is of great significance for the full and reasonable extraction and utilization of my country's precious rare earth resources.

(8) Chemical treatment: in the dissolution, washing, purification of rare earth ore and precipitation and burning of pure product solution, ultrasonic technology is used to strengthen the chemical separation process.

Description of drawings:

Fig. 1, Fig. 2, the production process schematic diagram of the present invention; Fig. 2 is the continuation figure of Fig. 1.

Detailed ways:

The present invention will be further described in more detail below with examples, but the present invention is not limited by these examples.

Example 1:

Main production equipment: stirring batching mixing tank, ultrasonic leaching equipment, ultrasonic extraction equipment, ionic membrane electrochemical reactor, stirring neutralization precipitation tank, ultrasonic crystallization tank, filtration solid-liquid separation device, pure water and pure acid equipment and analysis and testing instrument.

Main raw materials: sulfuric acid, hydrochloric acid, liquid ammonia, ammonium bicarbonate, ammonium carbonate, P204 extraction agent, P507 extraction agent, sulfuric acid intensified roasting method to smelt rare earth ores.

The process steps are as follows:

(1) Ultrasonic leaching: In a 1L stirred tank, add water, weigh 45g of the concentrated sulfuric acid roasting material of rare earth ore (the content of mixed rare earth oxide is greater than 30%), and add it to the ultrasonic leaching device, using an ultrasonic frequency of 19.8kHz, 250W For the probe-type ultrasonic generator, add the above-mentioned materials into a leaching device with a jacket of 1000ml through cooling circulating water, place the probe of the ultrasonic generator in the mixed material, control the operating temperature at 40°C, and conduct ultrasonication for 20 minutes. Finally, turn off the ultrasonic instrument, leaching the rare earth in the rare earth ore that has been roasted with sulfuric acid to obtain a rare earth solution, and the leachate is separated from the solid-liquid to obtain a sulfuric acid rare earth solution, which contains 30-50 g/L of rare earth oxides, Phosphorus 0.1-0.5g/L, iron 1.0-2.0g/L, thorium 0.01-0.1g/L, using ultrasonic leaching technology can improve the leaching rate and the leaching efficiency of rare earth.

(2) Neutralization and purification: Add the feed liquid obtained in the previous step into the stirring neutralization purification device, use ammonia as the neutralizing agent, and control the pH value to 3.5-5.5, so that non-rare earth impurities are precipitated, and after solid-liquid separation, Prepare pure sulfuric acid rare earth solution, the composition table of rare earth sulfuric acid solution before and after purification is shown in Table 1, and the percentage of various rare earth elements in the rare earth sulfuric acid solution after purification is shown in Table 2.

The composition of table 1 rare earth sulfuric acid solution

The percentage of various rare earth elements in rare earth sulfuric acid solution after purification in table 2

rare earth elements La₂O₃ CeO₂ Pr₆O₁₁ NdO₃ Sm₂O₃ Eu₂O₃ Gd₂O₃ Y₂O₃ other Content/% 27.23 48.70 5.20 15.20 1.20 0.24 0.36 0.11 1.2-1.3

Neutralization with ammonia or alkaline earth metal oxides can produce pure rare earth sulfate feed solution. In the process of preparing pure rare earth sulfate solution through solid-liquid separation, impurity elements such as phosphorus, iron, and thorium must be removed from the solution. , using ammonia or alkali metal oxides as a neutralizing agent will inevitably produce rare earth sulfate double salt precipitation, resulting in the loss of rare earth elements. If calcium oxide or calcium carbonate powder is used as a neutralizing agent to purify the rare earth sulfate solution, the generation of rare earth sulfate double salt can be avoided. However, due to the generation of calcium sulfate, the recovery rate of adsorbed rare earth elements will decrease as the amount of slag increases, so it is best to use liquid ammonia as a neutralizing agent. Therefore, in the separation and removal process of rare earth sulfate feed liquid, setting a solid-liquid separation process before neutralization and purification can greatly reduce the amount of precipitation of rare earth sulfate double salts, and at the same time use ammonia as a neutralizing agent to reduce the amount of rare earth sulfate feedstock. amount of water in the liquid system.

(3) Ultrasonic extraction grouping: In the tank type ultrasonic extraction equipment, di(2-ethylhexyl) phosphoric acid is used as the extraction agent, kerosene is used as the diluent, and the further refined sulfuric acid rare earth solution is directly used as the raw material for extraction and grouping. The concentration of mixed rare earth oxides in medium is less than 50g/L. The operating conditions of ultrasonic extraction are: the operating temperature is 35°C, the ultrasonic action intensity is 2.0W/cm ² , and the ultrasonic frequency is 19.8kHz, and the batch extraction and group separation are carried out. After fractional distillation, extraction and group separation, the water phase is cerium group light rare earth sulfate Concentrate; the organic phase is the yttrium group heavy rare earth sulfate enrichment; the water phase enters the next step of processing, and the organic phase enters step (8) for processing. Ultrasonic extraction grouping can significantly increase the rate of extraction grouping and the extraction grouping efficiency of rare earths. Using ultrasonic extraction grouping can increase the rate of extraction grouping by 20-60 times compared with traditional extraction grouping. In this separation process, due to the sulfuric acid solution of rare earths, When P204 is used as the extraction agent for extraction, the gadolinium-terbium separation coefficient β value is relatively large, and it is easy to group and separate gadolinium-terbium. Ultrasonic extraction and group separation of gadolinium-terbium, the condition is that the feed liquid contains 30-46g/L of rare earth oxides, the organic phase is a kerosene solution with a P204 content of 0.5-1.5mol/L, and the acidity of the lotion is 0.4-0.6 mol/L sulfuric acid. The flow ratio of the organic phase, feed liquid and washing liquid is 1:4-7:0.3-0.4. The content of rare earth oxides in the feed liquid is greater than 46g/L, which is close to the solubility of rare earth elements in sulfuric acid solution, and crystallization and precipitation of rare earth compounds are prone to occur. The content of rare earth oxides is less than 30g/L, which will increase the subsequent extraction equipment and increase the production capacity. Reduced, so 30-46g/L rare earth oxide is better. The concentration of extractant P204 in kerosene is greater than 1.5mol/L, which will increase the viscosity of the formed organic phase and make phase separation difficult. If it is less than 0.5mol/L, the production capacity will be reduced. If the acidity of the lotion exceeds 0.6 mol/L sulfuric acid, crystals of sulfates of rare earth elements will easily precipitate out. If the acidity of the lotion is less than 0.4 mol/L sulfuric acid, the washing effect will be poor. Under given operating conditions, good gadolinium-terbium group separation effects can be obtained. The organic phase discharged from the last stage of the countercurrent washing section is rich in heavy rare earth sulfates containing heavy rare earth elements such as gadolinium and dysprosium, and the content of rare earth oxides in the organic phase is 3-6g/L; the aqueous phase is enriched in light rare earth sulfates The rare earth oxide in the outlet water phase is 25-43g/L, and the concentration of its free acid is 0.08-0.13mol/L sulfuric acid. The outlet water phase is called sulfuric acid extraction multi-liquid containing light rare earth elements such as lanthanum, cerium, praseodymium and neodymium.

(4) Electrochemical oxidation: the aqueous sulfate enrichment solution in the previous step enters the anode chamber of the electrochemical reactor, under acidic conditions, the Ce ³⁺ in the rare earth solution is oxidized to Ce ⁴⁺ , and the solid-liquid Separation operation, separation from trivalent rare earth, the liquid phase enters the next step of treatment; the solid phase is crude cerium sulfate, and the crude cerium sulfate is washed, dissolved, purified, precipitated and burned to obtain cerium oxide products.

(5) Electrochemical reduction: the non-cerium light rare earth enrichment solution obtained through solid-liquid separation in the previous step enters the cathode chamber of the electrochemical reactor in the previous step. Under acidic conditions, the trivalent europium in the rare earth solution Eu ³ After ⁺ is reduced to divalent europium Eu ²⁺ , europium sulfate precipitates, which is separated from other trivalent rare earths through solid-liquid separation. The liquid phase enters the next step for further separation and purification; the solid phase is the crude europium sulfate, which is washed, dissolved, purified, precipitated and burned to obtain the europium oxide product.

(6) Ultrasonic extraction and fractionation grouping: Due to the very similar chemical properties of rare earth elements, it is difficult to separate rare earth elements in groups by single-stage extraction. Therefore, the ultrasonic fractional distillation extraction method was used. The fractional distillation extraction system consists of a countercurrent extraction section and a countercurrent washing section. The last stage of the countercurrent extraction section is used as the feed stage, and the organic phase solution containing the extractant enters the fractionation extraction system from the first stage of the countercurrent extraction section. The washing liquid enters the fractionation extraction system from the front stage of the countercurrent washing section, the water phase formed with the raffinate is discharged from the first stage of the countercurrent extraction section, and the feed liquid containing rare earth elements is discharged from the countercurrent extraction section. The final stage enters the fractional distillation extraction system. Put the liquid phase after solid-liquid separation in the previous step into the non-cerium and europium light rare earth solution into the ultrasonic extraction grouping device, and use the sulfuric acid raffinate of lanthanum rare earth oxide 17-28g/L as the feed liquid to adjust its pH To 1-5, kerosene is the diluent for extraction and grouping, the P204 content in the organic phase is 1.0-1.5mol/L, the organic phase:water phase is 1-3:1, and the water phase can be obtained as a lanthanum enrichment by performing countercurrent extraction , the lanthanum concentrate is washed, dissolved, purified, precipitated and burned to obtain lanthanum oxide products.

(7) Ultrasonic fractionation extraction and separation: the praseodymium-neodymium enrichment and gadolinium-terbium enrichment obtained from the organic phase obtained by countercurrent extraction in the previous step, and the praseodymium-neodymium enrichment and gadolinium-terbium enrichment are further ultrasonically fractionated Extract and separate, refine, wash, dissolve, purify, precipitate and burn to produce praseodymium oxide, neodymium oxide, samarium oxide, gadolinium oxide and terbium oxide products.

(8) Ultrasonic fractionation extraction grouping: the yttrium group heavy rare earth sulfate enrichment solution obtained by the ultrasonic extraction grouping in step (3) is used as the raw material liquid, and the organic phase containing medium heavy rare earth elements such as samarium, gadolinium, and terbium in the extraction liquid, After solvent extraction transformation, the rare earth sulfuric acid solution is converted into a rare earth hydrochloric acid solution with hydrochloric acid as the stripping liquid. In the process of extraction conversion, Ca ²⁺ , Mg ²⁺ and Fe ²⁺ impurities can be removed from the raffinate, and rare earths can be enriched by controlling the concentration and flow of the stripping agent. In the ultrasonic fractionation extraction grouping device, the obtained rare earth hydrochloric acid solution is used as the raw material liquid, and the mixture of 0.2-0.7mol/L P507 ammonium salt, 0.8-1.5mol/L P507 and kerosene is used as the organic phase, and the hydrochloric acid in the washing liquid is The concentration is 1.1-3.6mol/L, and its volume flow ratio is organic phase: raw material liquid: lotion is 0.85-3.5: 1: 0.12-0.70. During the fractionation, extraction, and grouping separation process, the molar concentration of rare earth in the raffinate phase is 0.1 -1.0mol/L, to obtain gadolinium-terbium enrichment and terbium-dysprosium enrichment, respectively use gadolinium-terbium enrichment and terbium-dysprosium enrichment as raw material liquid, further separate and refine to produce gadolinium oxide, terbium oxide and Enrichment of heavy rare earth oxidation products in dysprosium oxide.

Ce ₂ O ₃ , La ₂ O ₃ , Pr ₂ O ₃ , Nd ₂ O ₃ , 1Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₄ O ₇ , Dy ₂ O ₃ and Y ₂ O ₃ 10 kinds of products and 2 kinds of intermediate enrichment, realize the full utilization of rare earth resources, short process flow, high separation rate and efficiency, and stable process, easy operation, actual yield and total recovery of products The rate is higher.

Embodiment 2: with the rare earth sulfuric acid solution after the purification as the feed liquid of the fractional distillation extraction group separation of neodymium-samarium, the concentration of its rare earth is 45.38g/L, and feed liquid acidity is 0.06mol/L sulfuric acid, and organic phase is that P2O4 content is No. 260 solvent oil solvent of 1.0mol/L, washing liquid acidity is 0.572mol/L sulfuric acid, extraction section 4 grades, washing section 7 grades, altogether 11 grades, the flow ratio of organic phase, material liquid and washing liquid is 15 milliliters: 66 ml: 5.5 ml, the contact time between the organic phase and the water phase is 6 minutes, the extraction temperature is 27°C, the percentages of the rare earth elements in the feed solution are La ₂ O ₃ 27.53, CeO ₂ 49.70, Pr ₆ O ₁₁ 5.13, Nd ₂ O ₃ 15.44, Sm ₂ O ₃ 1.20, Eu ₂ O ₃ 0.23, Gd ₂ O ₃ 0.33, Y ₂ O ₃ 0.20. The sulfuric acid raffinate of samarium has a rare earth concentration of 41.33g/L rare earth oxide, a free acid concentration of 0.114mol/L sulfuric acid, and a rare earth concentration of 3.82 in the organic phase discharged from the seventh-stage organic phase outlet of the countercurrent washing section. g/L rare earth oxide. The recovery rate of Eu ₂ O ₃ in the organic phase is 99.15%, and the organic phase is the enrichment of medium and heavy rare earth elements such as samarium, europium, gadolinium, etc., and its composition is La ₂ O ₃ <0.1%, CeO ₂ <0.1%, Pr ₆ O ₁₁ <0.1%, Nd ₂ O ₃ 0.1%, Sm ₂ O ₃ 49.33%, Eu ₂ O ₃ 11.92%, Gd ₂ O ₃ 20.19%, Y ₂ O ₃ 11.05%, the composition of the water phase is La ₂ O ₃ 27.53%, CeO ₂ 49.70%, Pr ₆ O ₁₁ 5.13%, Nd ₂ O ₃ 15.44%, Sm ₂ O ₃ 1.20%, Eu ₂ O ₃ 0.23%, Gd ₂ O ₃ 0.37%, Y ₂ O ₃ 0.20% .

The organic phase loaded with samarium, europium, and gadolinium enrichment is stripped with 5mol/L hydrochloric acid as the stripping solution, and the chloride enrichment of rare earth elements such as samarium, europium, and gadolinium in the aqueous phase contains P204 No. 260 Solvent oil organic phase returns and recycles).

Embodiment 3: its experimental condition is basically the same as embodiment 4, and the difference is that the concentration of rare earth in the feed liquid is 30.17g/L rare earth oxide, and the acidity of feed liquid is 0.05mol/L sulfuric acid; Organic phase, feed liquid and washing liquid The flow ratio is 15 ml: 99 ml: 5.5 ml, and the extraction temperature is 23°C. The rare earth concentration in the water phase discharged from the water phase outlet was 27.89g/L rare earth oxide. The concentration of its free acid is 0.089mol/L sulfuric acid, and the rare earth concentration in the discharged organic phase from the organic phase is 3.92g/L rare earth oxide. The composition of the organic phase is Nd ₂ O ₃ <0.1%, Sm ₂ O ₃ 51.23%, Eu ₂ O ₃ 11.55%, the composition of the aqueous phase is La ₂ O ₃ 28.21%, CeO ₂ 50.80%, Pr ₆ O ₁₁ 5.23%, Nd ₂ O ₃ 16.35%, Sm ₂ O ₃ <0.1%, the recovery rate of Eu ₂ O ₃ is 100.12%, and the recovery rate of Nd ₂ O ₃ is 99%.

Embodiment 4: In fact, the face conditions are basically the same as in Example 5, except that the concentration of rare earth in the feed liquid is 35.26g/L rare earth oxide, and the acidity of the feed liquid is 0.06mol/L sulfuric acid; organic phase, feed liquid and lotion The flow ratio is 15 ml: 84 ml: 5.5 ml, and the extraction temperature is 28°C. The rare earth oxide concentration in the aqueous phase discharged from the aqueous phase outlet was 32.34 g/L. The concentration of free acid is 0.096mol/L sulfuric acid, and the concentration of rare earth in the organic phase discharged from the outlet of the organic phase is 4.05g/L rare earth oxide. The composition of the organic phase is Nd ₂ O ₃ <0.1%, Sm ₂ O ₃ 51.75%, Eu ₂ O ₃ 11.32%; the composition of the aqueous phase is La ₂ O ₃ 28.06%, CeO ₂ 50.7%, Pr ₆ O ₁₁ 5.32% %, Nd ₂ O ₃ 16.56%, Sm ₂ O ₃ <0.1%, and the recovery rate of Eu ₂ O ₃ is 99.3%).

Embodiment 5: its experimental condition is basically the same as embodiment 6, and the difference is that the concentration of rare earth in the feed liquid is 40.56g/L rare earth oxide, and the flow ratio of organic phase, feed liquid and washing liquid is 15 milliliters: 75 milliliters: 5.5 ml. The extraction temperature is 21°C. The rare earth concentration in the water phase discharged from the water phase outlet was 37.16 g/L rare earth oxide. The concentration of free acid is 0.104mol/L sulfuric acid, and the rare earth concentration in the organic phase discharged from the organic phase outlet is 4.10g/L rare earth oxide. The composition of the organic phase is Nd ₂ O ₃ <0.1%, Sm ₂ O ₃ 51.31%, Eu ₂ O ₃ 11.54%, the composition of the aqueous phase is La ₂ O ₃ 28.03%, CeO ₂ 50.96%, Pr ₆ O ₁₁ 5.30%, Nd ₂ O ₃ 16.31%, Sm ₂ O ₃ <0.1%.

Embodiment 6: its experimental condition is basically the same as embodiment 4, and the difference is that the concentration of rare earth in the feed liquid is 45.00g/L rare earth oxide, and the acidity of washing liquid is 0.556mol/L sulfuric acid; The organic phase, feed liquid and washing liquid The flow ratio is 15 milliliters: 100 milliliters: 4.8 milliliters, and the rare earth concentration in the water phase discharged from the water phase outlet is 42.60 g/L rare earth oxide. The free acid concentration is 0.091mol/L sulfuric acid, and the rare earth concentration in the organic phase discharged from the organic phase outlet is 5.90g/L rare earth oxide. The composition of the organic phase is Nd ₂ O ₃ 0.27%, Sm ₂ O ₃ 48.16%, Eu ₂ O ₃ 12.10%, the composition of the aqueous phase is La ₂ O ₃ 27.90%, CeO ₂ 50.45%, Pr ₆ O ₁₁ 5.31%, Nd ₂ O ₃ 16.52%, Sm ₂ O ₃ <0.1%.

Embodiment 7: its experimental condition is basically the same as embodiment 4, and the difference is that the concentration of rare earth in the feed liquid is 45.00g/L rare earth oxide, and the acidity of washing liquid is 0.556mol/L sulfuric acid; Organic phase, feed liquid and washing liquid The flow ratio is 15 milliliters: 100 milliliters, the rare earth concentration in the aqueous phase discharged from the aqueous phase outlet is 42.07g/L rare earth oxide, and the concentration of its free acid is 0.09mol/L sulfuric acid; in the organic phase discharged from the organic phase outlet The rare earth concentration is 5.92g/L rare earth oxide. The organic phase composition is Nd ₂ O ₃ <0.1%, Sm ₂ O ₃ 49.51%, Eu ₂ O ₃ 11.95%; the aqueous phase composition is La ₂ O ₃ 28.08%, CeO ₂ 50.62%, Pr ₆ O ₁₁ 5.27%, Nd ₂ O ₃ 16.52%, Sm ₂ O ₃ 0.11%.

Embodiment 8: The aqueous phase discharged by the fractional extraction of neodymium-sarium, that is, the sulfuric acid raffinate containing lanthanum, cerium, praseodymium, and neodymium, is used as the feed liquid for the separation of praseodymium-neodymium groupings, and the feed liquid is adjusted to pH4. It is 40.55g/L rare earth oxide, wherein the percentage of each rare earth element is as follows:

La ₂ O ₃ 27.02, CeO ₂ 51.42, Pr ₆ O ₁₁ 5.45, Nd ₂ O ₃ 16.62, Sm ₂ O ₃ 0.14, Eu ₂ O ₃ <0.1, others <0.1.

Use the following conditions to carry out fractional distillation, extraction and separation to prepare crude Nd ₂ O ₃ . The organic phase is No. 260 engine oil organic solvent with a P204 content of 1mol/L. The acidity of the lotion is 0.56mol/L sulfuric acid. The extraction section is 13 grades, and the washing section is 7 class. The flow ratio of the organic phase, the feed solution and the washing solution is 20 milliliters: 10 milliliters: 6.5 milliliters. The contact time between the organic phase and the aqueous phase was 6 minutes. The extraction temperature was 25°C. The discharged aqueous phase is a sulfuric acid raffinate containing lanthanum and cerium, its rare earth concentration is 20.71g/L rare earth oxide, and its free acid concentration is 0.27mol/L sulfuric acid. The aqueous phase composition is La ₂ O ₃ 35,16%, CeO ₂ 59.78%, Pr ₆ O ₁₁ 3.39%, Nd ₂ O ₃ 2.20%. The organic phase discharged from the seventh-stage organic phase outlet of the countercurrent washing section is composed of La ₂ O ₃ <0.1%, CeO ₂ 3.22%, Pr ₆ O ₁₁ 9.29%, Nd ₂ O ₃ 86.73%, Sm ₂ O ₃ 1.60%. The organic phase loaded with crude neodymium is back-extracted with 5 mol/L hydrochloric acid to obtain crude neodymium chloride, and the organic phase is returned for recycling.

Embodiment 9: Its experimental condition is basically the same as embodiment 10, and difference is that the flow ratio of organic phase, feed liquid and washing liquid is 20 milliliters: 10 milliliters: 7.0 milliliters. The rare earth concentration of the discharged water phase is 20.27g/L rare earth oxide, the concentration of free acid is 0.26mol/L sulfuric acid, and the composition of the water phase is La ₂ O ₃ 33.25%, CeO ₂ 57.83%, Pr ₆ O ₁₁ 4.93%, Nd ₂ O ₃ 4.40%; the organic phase composition is La ₂ O ₃ <0.1%, CeO ₂ 1.22%, Pr ₆ O ₁₁ 5.17%, Nd ₂ O ₃ 92.35%, Sm ₂ O ₃ 2.06%.

Example 10: The experimental conditions are basically the same as in Example 10, except that the acidity of the feed liquid is pH 1.3, the extraction section has 17 stages, and the washing section has 14 stages. The flow ratio of the organic phase, the feed solution and the washing solution is 15 milliliters: 10 milliliters: 4.5 milliliters. The rare earth concentration of the discharged aqueous phase is 23.24g/L rare earth oxide, and the concentration of its free acid is 0.28mol/L sulfuric acid. The aqueous phase composition is La ₂ O ₃ 36.81%, CeO ₂ 59.84%, Pr ₆ O ₁₁ 2.25%, Nd ₂ O ₃ 1.34%; the organic phase composition is La ₂ O ₃ <0.1%, CeO ₂ 3.11%, Pr ₆ O ₁₁ 12.8%, Nd ₂ O ₃ 82.97%, Sm ₂ O ₃ 1.60%.

Ce ₂ O ₃ , La ₂ O ₃ , Pr ₂ O ₃ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₄ O ₇ , Dy ₂ O ₃ , 10 kinds of products such as Y ₂ O ₃ and 2 kinds of intermediate concentrates; the process flow is short, and the process is stable, the operation is convenient, the equipment is easy to solve and maintain; the actual yield and total recovery rate of the product are high.

Claims (10)

1. A method for fully separating high-purity rare earth oxides from sulfuric acid-intensified roasting rare earth ores, characterized in that: ultrasonic leaching-ammonia neutralization purification-ultrasonic extraction-electrochemical valence change-chemical treatment combined separation technology, complete separation High-purity rare earth oxides Ce ₂ O ₃ , La ₂ O ₃ , Pr ₂ O ₃ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₄ O ₇ , Dy ₂ O ₃ and Y ₂ O ₃ , comprising the following process steps: (1) Ultrasonic leaching: In the ultrasonic leaching device, water or sulfuric acid aqueous solution containing rare earth in the process is used as the leaching agent for leaching operation, and the rare earth in the rare earth ore roasted by sulfuric acid is leached, and after solid-liquid separation, Obtain rare earth sulfate solution; (2) Neutralization and purification: in the stirring neutralization purification device, neutralize and purify with ammonia or alkaline earth metal oxides, and remove non-rare earth element impurities through solid-liquid separation to obtain pure rare earth sulfate solution; (3) Ultrasonic extraction grouping: In the ultrasonic extraction device, P204 is used as the extraction agent and kerosene is used as the diluent for extraction grouping. The aqueous phase is the light rare earth sulfate enrichment; the organic phase is the heavy rare earth sulfate enrichment; The phase is removed for further separation treatment, and the organic phase enters the step (8) for further separation treatment; (4) Electrochemical oxidation: The aqueous phase sulfate-rich solution obtained in the previous step enters the anode chamber of the electrochemical reactor. Under acidic conditions, Ce ³⁺ in the rare earth solution is oxidized to Ce ⁴⁺ , and simultaneously produces Ce(SO ₄ ) ₂ is precipitated, and after solid-liquid separation, the liquid phase enters the next step of treatment; the solid phase is crude cerium sulfate, and the crude cerium sulfate is washed, dissolved, purified, precipitated and burned to obtain cerium oxide product; (5) Electrochemical reduction: the non-cerium light rare earth enrichment solution obtained through solid-liquid separation in the previous step enters the cathode chamber of the electrochemical reactor in the previous step. Under acidic conditions, the trivalent europium in the rare earth solution Eu ³ After ⁺ is reduced to divalent europium Eu ²⁺ , europium sulfate EuSO ₄ precipitates, and after solid-liquid separation, it is separated from other trivalent rare earths, and the liquid phase enters the next step for further separation and purification; the solid phase is crude europium sulfate, Europium sulfate crude product is washed, dissolved, purified, precipitated and burned to obtain europium oxide product; (6) Ultrasonic extraction and fractionation grouping: the liquid phase after solid-liquid separation in the previous step is non-cerium and europium light rare earth solution, this solution enters the ultrasonic extraction grouping device, and the sulfuric acid with _La2O3 content of _17-28g /L The raffinate is the feed liquid, adjust its pH to 1-5, kerosene is the diluent for extraction and grouping, the P2O4 content in the organic phase is 1.0-1.5mol/L, and the volume ratio between the organic phase and the aqueous phase is 1-3 : 1, carry out counter-current extraction to obtain the aqueous phase as a lanthanum enrichment, and the lanthanum enrichment is washed, dissolved, purified, precipitated and burned to obtain a lanthanum oxide product; (7) Ultrasonic fractionation extraction and separation: the organic phase extracted in the previous step is praseodymium-neodymium enrichment and gadolinium-terbium enrichment, after further ultrasonic fractionation extraction and separation, refining, washing, dissolving, purification, precipitation and burning Obtain praseodymium oxide, neodymium oxide, gadolinium oxide and terbium oxide; (8) Ultrasonic fractionation extraction grouping: the heavy rare earth sulfate enrichment solution obtained in step (3) ultrasonic extraction grouping is used as the raw material liquid, and the organic phase containing heavy rare earth elements in samarium, gadolinium and terbium in the extract is extracted by solvent Transformation, using hydrochloric acid as the stripping solution, converting the rare earth sulfuric acid solution into a rare earth hydrochloric acid solution, removing Ca ²⁺ , Mg ²⁺ and Fe ²⁺ impurities from the raffinate during the extraction transformation process, and controlling the stripping agent concentration And the flow rate makes the rare earth enriched. In the ultrasonic fractionation extraction grouping device, the obtained rare earth hydrochloric acid solution is used as the raw material liquid; the mixture of 0.2-0.7mol/L P507 ammonium salt, 0.8-1.5mol/L P507 and kerosene For extracting the organic phase; the concentration of hydrochloric acid in the washing liquid is 1.1-3.6mol/L; its volume flow ratio is extracting the organic phase: raw material liquid: washing liquid=0.85-3.5: 1: 0.12-0.70, in this fractionation extraction group separation process , the molar concentration of rare earth in the raffinate phase is 0.1-1.0mol/L, and the gadolinium-terbium enrichment and terbium-dysprosium enrichment are obtained. Further separate and refine to produce heavy rare earth oxidation products in gadolinium oxide, terbium oxide and enriched dysprosium oxide. 2. The method for completely separating high-purity rare earth oxides from sulfuric acid-intensified roasting rare earth ores according to claim 1, characterized in that: the process conditions of the extraction operation are: the solid-liquid ratio is 1000g: 8-30L, and the operating temperature is 5 -50°C, the ultrasonic action intensity is 0.2-20.0W/cm ² , and the ultrasonic frequency is 19-80kHz. 3. The method for fully separating high-purity rare earth oxides from rare earth ores intensified with sulfuric acid roasting according to claim 1, characterized in that: the ultrasonic generating device is a probe type ultrasonic generator, a vibrator type ultrasonic generator, a vibrating plate type ultrasonic generator, etc. any of the generators. 4. The method for completely separating high-purity rare earth oxides from sulfuric acid-intensified roasting rare earth ores according to claim 1, characterized in that: in the ultrasonically enhanced rare earth leaching-extraction process, the ultrasonic leaching-extraction equipment is Tank-type extraction equipment or mixed-clarification extraction equipment or tubular extraction equipment with heat exchange devices and stirring devices; or continuous tank-type extraction equipment or mixed-clarification extraction equipment or tubes without heat exchange devices and stirring devices type extraction equipment. 5. The method for completely separating high-purity rare earth oxides from sulfuric acid-enhanced roasted rare earth ores according to claim 1, characterized in that: in the ultrasonic-enhanced rare-earth extraction process, the ultrasonic extraction is simple extraction or fractional extraction or group extraction; In the ultrasonic fractionation extraction process, a multi-component two-outlet process or a multi-component multi-outlet fractionation cascade extraction process is used. 6. The method for completely separating high-purity rare earth oxides from sulfuric acid-intensified roasting rare earth ores according to claim 1, characterized in that: when performing fractionation and group separation, the content of rare earth cerium oxide in the feed liquid is 30-46g/L, The acidity of the feed solution is pH=4 to 0.15mol/L sulfuric acid, the content of P204 in the organic phase is 0.5-1.5mol/L, and the concentration of sulfuric acid in the washing liquid is 0.4-0.6mol/L. 7. The method for completely separating high-purity rare earth oxides from rare earth ores enhanced by sulfuric acid roasting according to claim 1, characterized in that: the electrochemical reactor is a common flat plate electrochemical reactor or a three-dimensional electrochemical reactor ; The anode chamber and the cathode chamber of the electrochemical reactor are separated by a separator; in the anode chamber of the electrochemical reactor, the oxidation reaction of Ce ³⁺ is carried out, and in the cathode chamber, the reduction reaction of Eu ³⁺ is carried out, or 2 The two electrochemical reactors were used for the oxidation of Ce ³⁺ and the reduction of Eu ³⁺ , respectively. 8. The method for fully separating high-purity rare earth oxides from sulfuric acid-intensified roasting rare earth ores according to claim 1, characterized in that ammonia is added to the refined pure component rare earth solution to produce hydroxide crystals and precipitate out, and after Solid-liquid separation, get the hydroxide precipitate for analysis, if the purity does not meet the requirements of the product, repeat the above separation process until the purity requirement is reached; then use hydrochloric acid to dissolve the hydroxide precipitate to prepare a refined rare earth hydrochloride solution; In the refined rare earth hydrochloride, use active carbon or resin adsorption to further remove impurities; add ammonium bicarbonate or ammonium carbonate to the refined rare earth hydrochloride solution, and the resulting precipitate is separated in a solid-liquid separator, and the separated liquid phase is further separated to Single-component rare earth products are obtained; solid phase products are dried at 25-600°C to obtain rare earth carbonate products, and rare earth carbonate products are burned at 600-1000°C to obtain high-purity rare earth oxide products; in order to improve the separation and refining process and the quality of rare earth products Quality, during the sequential precipitation, crystallization, precipitation removal solid-liquid separation unit operation process, the ultrasonic strengthening process is adopted, and the process conditions of the ultrasonic strengthening process are: the operating temperature is 25-45 °C, and the ultrasonic action intensity is 2.0-5.0 W/cm ² , the ultrasonic frequency is 19-25kHz. 9. The method for completely separating high-purity rare earth oxides from sulfuric acid-intensified roasting rare earth ores according to claim 1, characterized in that: in the process of continuous separation of rare earth elements, the extractant is recycled and used in the process flow. In addition to returning the water to the unit process that matches the process conditions for recycling, the concentration of rare earth elements in the feed liquid is as high as possible under the conditions of the production process, and the excess water is evaporated by vacuum multi-effect evaporation. The concentration method increases the concentration of rare earth elements in the separation process, solves the problem of wastewater treatment at the same time, and realizes clean production in the process. 10. The method for completely separating high-purity rare earth oxides from sulfuric acid-intensified roasting rare earth ores according to claim 9, characterized in that: the absolute pressure of the vacuum multi-effect evaporation and concentration operation of the feed liquid is 0.001-0.008 MPa.

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