Method for reducing calcium in body in sulfuric acid rare earth extraction process
By separating the saponified organic phase and combining it with quantitative water dilution during the rare earth sulfate extraction process, the problem of CaSO4 precipitation caused by Ca2+ enrichment was solved, and the stable operation and efficient production of the extraction equipment were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA NORTHERN RARE EARTH (GROUP) HIGH TECH CO LTD
- Filing Date
- 2026-01-22
- Publication Date
- 2026-05-12
AI Technical Summary
In the rare earth sulfate extraction process, the traditional method of introducing the saponified organic phase leads to the enrichment of Ca2+ in the organic phase, forming CaSO4 precipitate, which causes scaling of the extraction equipment, difficulty in phase separation, and entrainment of the organic phase, affecting continuous production.
By splitting the saponified organic phase into multiple streams and introducing them into the rare earth saponification section through multiple inlets, and simultaneously diluting with a quantitative aqueous solution, the concentration of Ca2+ in the aqueous phase is controlled to avoid localized supersaturation and precipitation.
It significantly reduces scaling on equipment and pipelines, improves the continuous stability of the extraction system, reduces the frequency of downtime, and enhances the stable operation capability of the extraction process.
Smart Images
Figure CN122012956A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of rare earth element hydrometallurgical separation technology, specifically to a method for reducing calcium levels in vivo during rare earth sulfate extraction. Background Technology
[0002] The Bayan Obo rare earth mine in Baotou City mainly consists of bastnaesite and monazite. This type of rare earth ore is a high-calcium associated rare earth mineral. Rare earth oxides are typically prepared by the third-generation acid process, which includes a series of steps such as high-temperature roasting with concentrated sulfuric acid, extraction and separation, precipitation and impurity removal, and calcination. After treatment with concentrated sulfuric acid and high-temperature roasting, the rare earth ore is converted into a rare earth sulfate solution through water leaching and neutralization. During this process, some calcium will be present. 2+ Accompanying the rare earth sulfate solution, it enters the extraction process. The extraction and separation process includes: organic saponification section, rare earth saponification section, extraction section, washing section, and back-extraction section, ultimately yielding a pure rare earth chloride solution. In the extraction, separation, and purification process of the rare earth sulfate solution, P507 is typically used as a typical acidic phosphate ester extractant. Before entering the extraction section, P507 needs to be saponified with a clean, green, high-calcium-magnesium salt saponifying agent (such as magnesium oxide or magnesium bicarbonate) to improve its extraction capacity, selectivity, and separation efficiency.
[0003] Ca is present during the preparation of the above rare earth sulfate solution and saponifying agent. 2+ This allows the introduction of rare earth saponification into the Ca... 2 + It is in a supersaturated state. In traditional processes, the saponified organic phase enters the extraction tank from the front end, and a large amount of Ca2+ in the aqueous phase is extracted into the organic phase. When the rare earth content of the organic loading is low, the Ca2+ in the organic phase... 2+ It cannot be replaced by rare earth elements, even when loaded with a small amount of rare earth elements and a large amount of Ca. 2+ When organic matter encounters an aqueous phase with a high concentration of rare earth elements, a large amount of Ca is produced instantaneously. 2+ Rare earth elements displace the minerals into the aqueous phase, forming CaSO4 precipitate. Once formed, the CaSO4 precipitate cannot be dissolved by dilution water. Due to the limited solubility of CaSO4, this precipitate gradually accumulates in structural parts of the extraction tank, such as the mixing chamber, submerged chamber, and clarification chamber. This reduces the effective volume of the clarification chamber, makes phase separation difficult, increases the amount of organic phase entrainment, and in severe cases, can cause blockages in the extraction equipment and pipelines, affecting continuous production. Currently, factories mostly rely on manual, periodic cleaning of the crystallized deposits in the extraction tank, which is not only time-consuming and labor-intensive but also reduces system stability and increases the risk of shutdown.
[0004] Existing technologies have proposed solutions such as solvent extraction, chemical precipitation, and in vitro induced crystallization to reduce calcium precipitation. However, these methods generally suffer from problems such as complex processes, difficult operation and control, high rare earth loss rates, and a tendency to cause secondary scaling in equipment. Therefore, there is an urgent need for a novel treatment method that is simple in process, requires no additional chemical additives, and can effectively inhibit calcium precipitation. Summary of the Invention
[0005] The purpose of this invention is to provide a method for reducing calcium levels in vivo during rare earth sulfate extraction. This method involves changing the introduction method of the saponified organic phase, dividing it into multiple streams for introduction into the rare earth saponification section, and controlling the process with a quantitative aqueous solution for dilution, thereby reducing the calcium content in the organic phase. 2+ It no longer concentrates and enriches, thus avoiding the local concentration from exceeding the solubility product and causing CaSO4 precipitation.
[0006] To achieve the above objectives, the technical solution used in this invention is: Methods for lowering calcium levels in vivo during rare earth sulfate extraction include: The saponified organic phase that has undergone saponification is separated and introduced into the rare earth saponification section of the rare earth extraction process through multiple inlets. In the last stage of the extraction tank, rare earth sulfate solution is added, along with dilution water, to increase the total volume of the aqueous phase in the rare earth saponification section and dilute the Ca ion concentration in the aqueous phase.
[0007] Furthermore, the raffinate outlet of the rare earth saponification section is stage 1. The saponification organic phase uses P507 organic phase. The P507 organic phase that has undergone saponification is split into 'a' streams, where 2 ≤ a ≤ N / 2, and introduced into the rare earth saponification section of the rare earth extraction process through multiple inlets. The rare earth saponification section has at least N stages, where N ≥ 4. The last saponification organic phase is 'a'. n The import level is level N-1.
[0008] Furthermore, the adjacent inlets of the saponified organic phase are spaced 1-2 levels apart.
[0009] Furthermore, when the rare earth saponification section is an N+1 level odd-number system, the saponified organic phase is divided into N / 2 streams that enter the rare earth saponification section from the odd-number extraction stage.
[0010] Furthermore, the saponified organic phase is a mixed saponified organic phase obtained by saponifying magnesium bicarbonate soap, magnesium oxide soap, or magnesium bicarbonate soap and magnesium oxide soap together.
[0011] Furthermore, under operating temperatures of 20℃-65℃, CaSO4 crystallization during the P507-sulfuric acid rare earth extraction and separation process is reduced by diverting the saponified organic phase into the rare earth saponification section.
[0012] Furthermore, at the end of the rare earth saponification section, dilution water at a flow rate of 1-5 times that of the rare earth sulfate solution is added.
[0013] Furthermore, dilution water at a flow rate of 1-2 times that of rare earth sulfate solution is added at the end of the rare earth saponification section.
[0014] Furthermore, P507 is selected from 2-ethylhexyl phosphate mono-2-ethylhexyl ester.
[0015] Furthermore, it is applicable to the green and efficient separation of high-calcium saponifying agents and high-calcium associated rare earth minerals, the removal of non-rare earth impurities during the extraction process, or related extraction systems using other saponifying agents.
[0016] The technical effects of this invention include: 1. This invention utilizes a dual synergistic regulation of "introduction of saponified organic phase in separate flow" and "quantitative dilution with aqueous solution" to prevent the formation of high-concentration CaSO4 aggregates in the local aqueous phase when the saponified organic phase enters the rare earth saponification section. This fundamentally weakens local supersaturation conditions, significantly reduces the tendency of CaSO4 precipitation, and thus significantly reduces scaling and deposition in the mixing chamber, submerged chamber, clarification chamber, and related equipment pipelines of the extraction tank. This reduces the frequency of manual tank cleaning and production shutdowns for maintenance, and improves the continuous and stable operation capability of the extraction process.
[0017] In existing technologies, the pre-saponification of P507 using magnesium oxide or magnesium bicarbonate often leads to calcium sulfate (CaSO4) precipitation during rare earth extraction due to the high calcium content in the raw materials and system. This precipitation causes scaling in the mixing, submerged, and clarifying chambers, resulting in difficulties in phase separation, increased organic phase entrainment, and even pipeline blockage. This application addresses the problem by changing the introduction method of the saponified organic phase. The organic phase is diverted and introduced into the rare earth saponification section via multiple inlets. Simultaneously, a quantitative aqueous solution is added for dilution, achieving the desired calcium ion concentration (CaSO4). 2+ This method effectively diffuses and reduces concentration peaks in the aqueous phase, preventing local concentrations from reaching the solubility product and causing precipitation. It requires no additional chemical additives, is simple in process, and can effectively reduce or eliminate CaSO4 precipitation and crystallization in equipment and pipelines, reducing downtime for tank cleaning and significantly improving the continuous operation stability of the extraction system. It can be directly applied to extraction production lines with high calcium content in saponifying agents and rare earth solutions.
[0018] The method for reducing calcium levels in vivo during rare earth sulfate extraction provided in this application is applicable to the rare earth fractional extraction process of the P507-sulfuric acid system. By changing the introduction method of the saponified organic phase, dividing it into a multi-inlet rare earth saponification section, and using quantitative aqueous solution dilution control, the calcium content in the organic phase is reduced. 2+ This method avoids concentrated accumulation, thus preventing local concentrations from exceeding the solubility product and causing CaSO4 precipitation. This application addresses the issue in existing technologies where magnesium salt saponification P507, during rare earth saponification in a sulfuric acid system, readily reacts with SO4 due to the high calcium content in the sulfuric acid rare earth feed solution and saponifying agent. 2-The formation of CaSO4 crystals leads to scaling in the mixing chamber, submerged chamber, clarifier, and pipelines, causing difficulties in phase separation, increased organic phase entrainment loss, and suboptimal continuous operation. This method can effectively reduce localized CaO formation in the system. 2+ and SO4 2- The concentration peak is reduced, or CaSO4 crystallization is reduced or avoided, and scale buildup in the mixing chamber, submerged chamber, clarification chamber and related pipelines is reduced or avoided, thereby reducing the frequency of downtime for tank cleaning and improving the long-term stability of the extraction system.
[0019] This application proposes for the first time a method in rare earth smelting and extraction processes where a high-calcium organic phase is diffused and distributed throughout the system by introducing a saponified organic phase in a split manner and coordinating it with a quantitative aqueous solution for dilution. This reduces the local ion concentration in the aqueous phase, effectively inhibiting CaSO4 scaling in equipment and pipelines and improving the stable operation of the extraction process. This application creatively proposes a method for organic phase splitting, where the saponified P507 organic phase is split and introduced into the rare earth saponification section through multiple inlets, while simultaneously being diluted with a quantitative aqueous solution to achieve CaSO4 scaling. 2+ Effective diffusion and concentration reduction in the aqueous phase prevent local concentrations from reaching their solubility product and causing precipitation. This fundamental process change overturns the traditional "front-end calcium enrichment" model, achieving back-end calcium displacement. Specifically, it allows the high-concentration rare earth sulfate solution to first contact most of the organic phase, utilizing the excess rare earth ions in the aqueous phase to control the calcium concentration in the organic phase. 2+ The substitution, thereby replacing Ca 2+ It smoothly "carries out" the system in a dissolved state, fundamentally avoiding the loss of Ca. 2+ Localized supersaturation leads to concentrated precipitation. This process requires no additional chemical additives, is simple, and can effectively reduce or eliminate crystallization and scaling on equipment and pipelines, reduce the frequency of downtime for tank cleaning, and significantly improve the continuous operation stability of the extraction system.
[0020] 2. By introducing the saponified organic phase in a separate flow, the flow rate of the first two stages of the extraction tank is reduced, allowing for the addition of a higher proportion of water for dilution. This helps to further reduce the local peak concentration of CaSO4, inhibit CaSO4 supersaturation crystallization, reduce residue and crystal enrichment, and create conditions for the system to achieve long-term stable operation.
[0021] 3. This application is highly compatible with existing extraction processes. It does not require changes to the extraction tank, mixing and clarifier or the main process flow, nor does it require the introduction of new energy-consuming equipment. It only requires laying the diversion pipelines for the saponified organic phase and the diluted aqueous solution and the flow control device on the existing box-type mixing and clarifier system. The project is simple to implement and has low investment costs, making it suitable for rapid industrialization promotion by existing rare earth smelting enterprises.
[0022] 4. This invention effectively overcomes the shortcomings of high-calcium saponified organic compounds in sulfuric acid systems, which easily lead to slag formation and CaSO4 blockage. It significantly reduces CaSO4 deposition in the extraction tank and related equipment, improves the operational stability and continuity of high-calcium leachate in the rare earth extraction process in sulfuric acid systems, ensures that product purity and rare earth recovery rate remain at a stable level, and provides an important guarantee for efficient and low-maintenance operation in industrial production.
[0023] 5. Strong technical compatibility.
[0024] This method is applicable to the saponification and organic extraction of rare earth production in the sulfuric acid system in all hydrometallurgical processes of high-calcium associated rare earth ores. Its core is the dual synergistic regulation of "saponification organic phase separation" and "quantitative aqueous solution dilution" in vivo, and it has a wide range of applications.
[0025] 6. Low implementation cost, simple operation, and strong adaptability.
[0026] No structural modifications to the existing box-type mixing and clarifying extraction tank are required, no high-energy-consuming equipment is added, and no external treatment is necessary. Only branch lines, valves, and flow meters need to be added to the existing system. The modification work is minimal, short-term, and low-risk. The modification cost is far lower than the downtime losses and cleaning costs caused by equipment scaling.
[0027] This method is based on the optimization and adjustment of existing process parameters. Operators can master it with simple training, and it is easy to replicate and promote in other rare earth extraction production units.
[0028] This application is characterized by its strong applicability and wide range of applications. It is applicable to extraction processes in the rare earth industry and is not limited by operating temperature, production capacity, rare earth concentration, etc. It only requires adjusting the amount of saponified organic fraction, the amount of water used for dilution, and the number and location of addition points according to different conditions. Attached Figure Description
[0029] Figure 1 This is a flowchart of the in vivo calcium reduction method during rare earth sulfate extraction in this invention; Figure 2 This is a schematic diagram showing the presence of a large amount of CaSO4 precipitate in the rare earth saponification stage in Comparative Example 1 of the present invention; Figure 3 This is a schematic diagram showing the absence of precipitation or entrainment in the rare earth saponification section of Embodiment 1 of the present invention. Detailed Implementation
[0030] The following description fully illustrates specific embodiments of the present invention to enable those skilled in the art to practice and reproduce it. To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
[0031] The method for reducing calcium levels in the rare earth sulfate extraction process is applicable to the green and efficient separation of high-calcium saponifying agents and associated rare earth minerals, as well as the removal of non-rare earth impurities (slightly soluble salt crystal precipitation) during extraction. It is also suitable for related extraction systems using other saponifying agents. In the magnesium salt saponification P507 (2-ethylhexyl phosphate mono-2-ethylhexyl ester)-rare earth sulfate extraction system, a strategy combining changing the feeding method of the saponifying organic phase with quantitative dilution of the aqueous solution reduces calcium levels. 2+ The concentration is enriched, thereby reducing or eliminating the formation of CaSO4 precipitate.
[0032] like Figure 1 The diagram shown is a flowchart of the in vivo calcium reduction method during rare earth sulfate extraction in this invention.
[0033] Step 1: The P507 organic phase (saponified organic phase) that has completed the saponification process is split and introduced into the rare earth saponification section of the rare earth extraction process through multiple inlets. The raffinate outlet of the rare earth saponification section is stage 1. The P507 organic phase (saponified organic phase) that has undergone saponification is split into a streams (at least two streams, 2≤a≤N / 2), which are then introduced into the mixing chamber of the rare earth saponification section of the rare earth extraction process (at least N stages, N≥4) via multiple inlets. The last stream of saponified organic phase a... n The import level is level N-1.
[0034] The interval between adjacent inlets of the saponified organic phase should be 1-2 stages, and preferably no more than two stages, to prevent hysteresis reactions caused by multiple cation substitutions, which could lead to Ca... 2+ Local concentration imbalance occurs. When the rare earth saponification section is an N+1 level odd-number system, the saponified organic phase is divided into N / 2 streams that enter the rare earth saponification section from the odd-number extraction stage.
[0035] This technique allows the saponified organic phase to be orderly dispersed into different sections of the mixing chamber in a multi-stage rare earth extraction process, avoiding enrichment at a single point, unlike traditional single-inlet, non-splitting extraction processes. By using a multi-inlet diversion method, the high-calcium saponified organic phase is guided to disperse into the rare earth saponification section of the rare earth extraction process, preventing localized enrichment at a single point and thus avoiding CaSO4 supersaturation precipitation.
[0036] By introducing the saponified organic phase in a separate flow, the flow rate of the first two stages of the extraction tank is reduced, allowing for the addition of a higher proportion of water for dilution. This helps to further reduce the local peak concentration of CaSO4, inhibit CaSO4 supersaturation crystallization, reduce residue and crystal enrichment, and create conditions for the system to achieve long-term stable operation.
[0037] Under operating temperatures of 20℃-65℃, the crystallization of CaSO4 during the P507-sulfuric acid rare earth extraction and separation process is reduced by diverting the saponified organic phase into the rare earth saponification section. P507 can be obtained by saponifying magnesium bicarbonate soap, magnesium oxide soap, or a mixture of saponified organic phases.
[0038] Step 2: Add rare earth sulfate solution to the last stage of the extraction tank, along with dilution water at a flow rate of 1-5 times the rare earth sulfate solution, to increase the total volume of the aqueous phase in the rare earth saponification section, thereby diluting the Ca in the aqueous phase. 2+ concentration.
[0039] At the end of the rare earth saponification section, dilution water at a flow rate of 1-2 times that of rare earth sulfate solution is added. 1-2 times is the economic value in the rare earth production process. The actual water volume needs to be adjusted synchronously according to the specific process parameters and is not limited to this value.
[0040] For example, the saponified organic phase can be divided into two streams and enter the rare earth saponification section. The first stream of saponified organic phase enters the first stage of the mixing chamber of the rare earth saponification section, and the second stream of saponified organic phase enters the third stage of the mixing chamber of the rare earth saponification section.
[0041] The saponified organic phase is thoroughly mixed with the diluted aqueous phase in the third-stage mixing chamber. In the presence of excess rare earth ions, the Ca introduced into the organic phase... 2+ Displacement and transfer occur into the aqueous phase; after dilution with a measured amount of water, the Ca in the third-stage aqueous phase is reduced. 2+ The concentration must always be kept below the allowable value for the process.
[0042] Meanwhile, a certain amount of rare earth ions still exist in the second-stage aqueous raffinate, which can promote the dissolution of CaSO4, thereby further reducing the risk of local supersaturation and crystallization in the aqueous phase.
[0043] The saponified organic phase enters the first-stage mixing chamber and comes into countercurrent contact with the raffinate from the third stage in the second stage to extract the residual rare earth ions in the aqueous phase. This ensures that the rare earth content in the raffinate discharged from the first stage meets the emission control requirements and avoids the loss of rare earth due to diversion and dilution.
[0044] Ca entering the rare earth saponification stage 2+ Although with SO4 in the system 2- The reaction forms sparingly soluble CaSO4, but it does not reach saturation. The raffinate enters from the last stage and exits from the first stage. The reaction products can be discharged from the system with the first-stage raffinate, thus avoiding the deposition and scaling inside the equipment.
[0045] By introducing the saponified organic phase separately and diluting it with a quantitative aqueous solution, the slightly soluble CaSO4 in the rare earth saponification section can form a stable unsaturated solution diffusion distribution, which reduces the local peak concentration of CaSO4 in the aqueous phase. This significantly reduces the risk of CaSO4 crystallization and scaling in the mixing chamber, submerged chamber, clarification chamber and related pipelines of the extraction equipment, and improves the continuous operation stability of the extraction system.
[0046] Comparative Example 1 The leaching solution of a mixed rare earth ore containing fluorite, cerium, lanthanum, and monazite first undergoes a transformation pre-separation of Ca. 2+ (Ca) 2+ (Content 0.6-1.3g / L, pH=4.5-5), then proceeds to the fourth stage of rare earth saponification.
[0047] like Figure 2 The diagram shown is a schematic diagram of the presence of a large amount of CaSO4 precipitate in the rare earth saponification stage in Comparative Example 1 of the present invention.
[0048] The rare earth sulfate feed solution enters stage 4, while the high-calcium-magnesium salt saponified organic (P507 / sulfonated kerosene) phase is entirely fed into stage 1. Operating under a saponified organic / rare earth feed solution ratio of 1.1:1, the system saponification degree is 0.45-0.5 mol / L, and a large amount of CaSO4 precipitate appears in the rare earth saponification section.
[0049] Example 1 The leaching solution of a mixed rare earth ore containing fluorite, cerium, lanthanum, and monazite first undergoes a transformation pre-separation of Ca. 2+ (Ca) 2+ (Content 0.6-1.3g / L, pH=4.5-5), then proceeds to the fourth stage of rare earth saponification.
[0050] like Figure 3 The diagram shown is a schematic diagram of the rare earth saponification section in Embodiment 1 of the present invention, which shows no precipitation or entrainment phenomenon.
[0051] The rare earth sulfate feed solution enters stage 4. The high-calcium magnesium salt saponified organic (P507 / sulfonated kerosene) phase is partially sent to stage 1, and the remainder to stage 3. Simultaneously, 1.5-1.7 times the flow rate of dilution water is sent to stages 3 and 4, ensuring that the calcium-magnesium salt saponified organic (P507 / sulfonated kerosene) phase entering the extraction section is diluted. 2+ The concentration was reduced to 1.0-1.35 g / L. Under the condition of saponification organic / rare earth feed solution = 1.1:1, the saponification degree of the system was 0.45-0.5 mol / L. After 120 hours of continuous operation, no obvious precipitation was observed, the rare earth extraction rate was stable at over 98%, the clarification interface was clear, and there was no precipitation or entrainment.
[0052] Comparative Example 2 The leaching solution of a mixed rare earth ore containing fluorite, cerium, lanthanum, and monazite first undergoes a transformation pre-separation of Ca. 2+ (Ca) 2+ (Content 0.6-1.3g / L, pH=4.5-5), then proceeds to the fourth stage of rare earth saponification.
[0053] The rare earth sulfate feed solution enters stage 4. A portion of the high-calcium magnesium salt saponified organic (P507 / sulfonated kerosene) phase is first sent to stage 2, and the remainder to stage 3. Simultaneously, 1.5-1.7 times the flow rate of dilution water is sent to stages 3 and 4, ensuring that the calcium-magnesium salt saponified organic (P507 / sulfonated kerosene) phase entering the extraction section is diluted. 2+ The concentration was reduced to 1.0-1.35 g / L. Under the condition of saponification organic / rare earth feed solution = 1.1:1, the saponification degree of the system was 0.45-0.5 mol / L. No obvious precipitation was observed after 120 hours of continuous operation, but the REO in the first-stage raffinate was 0.7 g / L, indicating a loss of rare earth elements.
[0054] Example 2 The leaching solution of a mixed rare earth ore containing fluorite, cerium, lanthanum, and monazite first undergoes a transformation pre-separation of Ca. 2+ (Ca) 2+ (Content 0.6-1.3g / L, pH=4.5-5), then proceeds to the sixth stage of rare earth saponification.
[0055] The rare earth sulfate feed solution enters stage 6. The high-calcium-magnesium salt saponified organic (P507 / sulfonated kerosene) phase is partially sent to stage 1, and the remainder to stages 3 and 5. Simultaneously, 1.5-1.7 times the flow rate of the rare earth sulfate feed solution is diluted with water and sent to stages 5 and 6 to reduce the Ca2+ concentration in the aqueous phase entering the extraction section to 1.0-1.35 g / L. Operating under a saponified organic / rare earth feed solution ratio of 1.1:1, no significant precipitation was observed after 120 hours of continuous operation. The rare earth extraction rate remained stable above 98%, with a clear interface and no precipitation or entrainment.
[0056] Comparative Example 3 A rare earth ore leaching solution first undergoes a transformation pre-separation of Ca. 2+ (Ca) 2+(Content 0.6-1.3g / L, pH=4.5-5), then proceeds to the sixth stage of rare earth saponification.
[0057] The rare earth sulfate feed solution enters stage 6. A portion of the high-calcium-magnesium salt saponified organic (P507 / sulfonated kerosene) phase is first sent to stage 1, and the remainder to stage 5. Simultaneously, 1.5-1.7 times the flow rate of dilution water is sent to stages 5 and 6, ensuring that the Ca phase entering the extraction section... 2+ The concentration decreased to 1.0-1.35 g / L. Under the condition of a saponification organic / rare earth feed solution ratio of 1.1:1, the rare earth concentration in the raffinate was found to be 0.36 g / L during the extraction process, indicating rare earth loss. After 2 hours, significant calcium precipitation appeared in the second-stage extraction tank.
[0058] Example 3 A rare earth ore leaching solution first undergoes a transformation pre-separation of Ca. 2+ (Ca) 2+ (Content 0.6-1.3g / L, pH=4.5-5), then proceeds to the sixth stage of rare earth saponification.
[0059] The rare earth sulfate feed solution enters stage 6. A portion of the high-calcium magnesium salt saponified organic (P507 / sulfonated kerosene) phase is first sent to stage 1, and the remainder to stage 4. Simultaneously, 1.5-1.7 times the flow rate of dilution water is sent to stages 5 and 6, ensuring that the calcium-magnesium salt saponified organic (P507 / sulfonated kerosene) phase entering the extraction section is diluted. 2+ The concentration was reduced to 1.0-1.35 g / L. Under the condition of a saponification organic / rare earth feed solution ratio of 1.1:1, no significant precipitation was observed after 120 hours of continuous operation.
[0060] Example 4 A rare earth ore leaching solution first undergoes a transformation pre-separation of Ca. 2+ (Ca) 2+ The content is 0.6-1.3 g / L, pH=4.5-5), and then it enters the sixth stage of rare earth saponification. The rare earth sulfate feed solution enters the sixth stage, where a portion of the high-calcium magnesium salt saponified organic (P507 / sulfonated kerosene) phase is first sent to the second stage, and the remainder to the fourth stage. Simultaneously, 1.5-1.7 times the flow rate of dilution water is sent to the fifth and sixth stages, so that the Ca in the aqueous phase entering the extraction stage... 2+ The concentration was reduced to 1.0-1.35 g / L. Under the condition of a saponification organic / rare earth feed solution ratio of 1.1:1, no significant precipitation was observed after 120 hours of continuous operation.
[0061] The terminology used in this invention is descriptive and exemplary, not restrictive. Since this invention can be embodied in many forms without departing from the spirit or essence of the technical solution, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims. Therefore, all variations and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.
Claims
1. A method for lowering calcium levels in vivo during rare earth sulfate extraction, characterized in that, include: The saponified organic phase that has undergone saponification is separated and introduced into the rare earth saponification section of the rare earth extraction process through multiple inlets. In the last stage of the extraction tank, rare earth sulfate solution is added, along with dilution water, to increase the total volume of the aqueous phase in the rare earth saponification section and dilute the Ca ion concentration in the aqueous phase.
2. The method for reducing calcium levels in vivo during rare earth sulfate extraction as described in claim 1, characterized in that, The raffinate outlet of the rare earth saponification section is stage 1. The saponification organic phase uses P507 organic phase. The P507 organic phase after saponification is split into 'a' streams, where 2 ≤ a ≤ N / 2. These streams are introduced into the rare earth saponification section of the rare earth extraction process via multiple inlets. The rare earth saponification section has at least N stages, where N ≥ 4. The last stream of saponified organic phase is 'a'. n The import level is level N-1.
3. The method for reducing calcium in vivo during rare earth sulfate extraction as described in claim 2, characterized in that, The adjacent inlets of the saponified organic phase are spaced 1-2 levels apart.
4. The method for reducing calcium in vivo during rare earth sulfate extraction as described in claim 2, characterized in that, When the rare earth saponification section is an N+1 level odd-number system, the saponified organic phase is divided into N / 2 streams that enter the rare earth saponification section from the odd-number extraction stage.
5. The method for reducing calcium in vivo during rare earth sulfate extraction as described in claim 1, characterized in that, The saponified organic phase is a mixed saponified organic phase obtained by saponifying magnesium bicarbonate soap, magnesium oxide soap, or magnesium bicarbonate soap and magnesium oxide soap together.
6. The method for reducing calcium in vivo during rare earth sulfate extraction as described in claim 2, characterized in that, Under operating temperatures of 20℃-65℃, CaSO4 crystallization is reduced during the P507-sulfuric acid rare earth extraction and separation process by diverting the saponified organic phase into the rare earth saponification section.
7. The method for reducing calcium in vivo during rare earth sulfate extraction as described in claim 1, characterized in that, Add dilution water at a flow rate of 1-5 times that of rare earth sulfate solution at the end of the rare earth saponification section.
8. The method for reducing calcium in vivo during rare earth sulfate extraction as described in claim 7, characterized in that, Add dilution water at a flow rate of 1-2 times that of rare earth sulfate solution at the end of the rare earth saponification section.
9. The method for reducing calcium in vivo during rare earth sulfate extraction as described in claim 2, characterized in that, P507 uses 2-ethylhexyl phosphate mono-2-ethylhexyl ester.
10. The method for reducing calcium in vivo during rare earth sulfate extraction as described in claim 1, characterized in that, It is suitable for the green and efficient separation of high-calcium saponifying agents and high-calcium associated rare earth minerals, the removal of non-rare earth impurities during the extraction process, or related extraction systems using other saponifying agents.