Solvent extraction unit for removing calcium
By distributing aqueous droplets into the organic phase in the solvent extraction unit to precipitate calcium compounds, the problems of water waste and equipment blockage in existing technologies are solved, achieving efficient and economical calcium removal.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- METSO FINLAND OY FI
- Filing Date
- 2025-01-17
- Publication Date
- 2026-07-24
Smart Images
Figure CN224541026U_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a solvent extraction unit for removing calcium. Background Technology
[0002] In the field of hydrometallurgy, solvent extraction is a widely used method for separating metal ions. Currently, this system is designed for liquids only, therefore precipitates and solids must be avoided at all costs. The presence of solids in current solvent extraction systems poses several problems, as solids can clog flow and equipment, and may also form stable emulsions, negatively impacting the separation process.
[0003] In some extraction methods, precipitated compounds may form when ions are transferred between two liquid phases. To avoid this problem, the amounts of the aqueous and / or organic phases must be adjusted to keep the precipitated compounds in solution. This is especially true for calcium-containing compounds originating from, for example, raw materials, neutralizing agents, or feed water in metal leaching processes. Since calcium can cause problems in subsequent steps of the separation process, it is beneficial to remove excess calcium.
[0004] Calcium-based neutralizing chemicals are generally inexpensive and readily available. Therefore, calcium-based chemicals, such as limestone (CaCO3) or lime (Ca(OH)2), may be a good choice for pH control during solvent extraction. A drawback is that calcium compounds can easily precipitate in the presence of counterions, thus clogging the equipment. This problem becomes particularly pronounced in sulfate-based solutions by the formation of gypsum, which tends to adhere to the equipment surface in solid form.
[0005] In existing technologies, precipitation is avoided by increasing the relative volume of the aqueous phase, preventing chemical equilibrium from being reached and thus keeping calcium compounds in solution. This method may require large amounts of water, which can be a very limited resource in some places, such as Australia, Africa, and parts of Asia. Furthermore, this increases the amount of wastewater generated in the process. Additionally, the feed water may contain relatively high levels of calcium, especially in desert regions, reducing the efficiency of the calcium removal method. Current methods are typically executed at the highest possible stage efficiency, reaching 98% or higher. To avoid using more water than necessary, the water leaving the extraction process is almost saturated for calcium compounds (e.g., calcium sulfate).
[0006] Current extraction methods still rely on vigorous mixing to increase the reaction surface area and mass transfer of metals between the aqueous and liquid phases. This presents further problems when precipitates or solids are present, as vigorous mixing often creates emulsions into which solids can bind. Gypsum, in particular, is prone to forming cruds, which are emulsions of organic, aqueous, and solid phases. Newly formed gypsum is highly reactive and tends to adhere to the inner surfaces of solvent extraction units and pipes. When gypsum forms under vigorous mixing, organic matter typically binds to the wet precipitate, and the mixing further directs the precipitate into contact with the inner surfaces of the equipment. Gypsum accumulation in the equipment necessitates periodic maintenance shutdowns.
[0007] Some existing solutions utilize alternative flow arrangements instead of mixing. For example, EP 2614868B1 and US 2022 / 0332751 A1 both describe liquid-liquid extraction units. In EP 2614868 B1, the unit is arranged as a countercurrent unit, where the aqueous phase in the form of bubbles enters from an upper inlet in one sidewall, and the organic phase in the form of bubbles enters from a lower inlet. US 2022 / 0332751 A1 relates to a multi-stage apparatus for liquid-liquid extraction, where the liquid is arranged to flow from one baffle to another. Neither of these publications addresses the removal of precipitates, although US 2022 / 0332751 A1 briefly touches on the issue, noting that maintenance can be reduced due to the absence of piping connecting each stage.
[0008] Considering the aforementioned problems with existing technologies, there is still a need for a solvent extraction method and system that utilizes water resources more effectively in the calcium removal process. Utility Model Content
[0009] This utility model is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims.
[0010] According to a first aspect of the present invention, a solvent extraction method for removing calcium is provided. In this method, an aqueous extraction solution is dispensed into an organic phase with a density lower than that of the aqueous extraction solution. The method further includes the following steps:
[0011] - The droplets of the aqueous extraction solution are distributed in the upper part of the solvent extraction unit.
[0012] - The droplets are guided through the organic phase toward the bottom of the solvent extraction unit, where they are collected into the aqueous phase layer.
[0013] - At the bottom of the solvent extraction unit, the aqueous slurry containing precipitated calcium compounds is removed from the bottom portion of the aqueous phase layer.
[0014] Therefore, a first aspect of this invention relates to a method for removing calcium in a solvent extraction system. Droplets of an aqueous phase are distributed into an organic phase, causing calcium compounds to precipitate within the aqueous droplets. The droplets travel downwards and are collected in an aqueous layer, from which a precipitate forms.
[0015] According to a second aspect of the present invention, a solvent extraction unit is provided, wherein the upper part of the solvent extraction unit has an aqueous extraction solution inlet and an organic solvent outlet. The solvent extraction unit further includes:
[0016] - An extraction solution dispenser, located below the level of the organic solvent outlet, is configured to dispense the aqueous extraction solution from the aqueous extraction solution inlet into the organic phase as aqueous droplets.
[0017] - Organic solvent inlet, located at the bottom of the solvent extraction unit.
[0018] - A concentrator section for collecting precipitate from the bottom of the solvent extraction unit, wherein the concentrator section is located at a level below the organic solvent inlet at the bottom of the solvent extraction unit, and includes structures for guiding the precipitate toward the bottom of the solvent extraction unit, and
[0019] - Slurry outlet connected to the thickener section.
[0020] Therefore, a second aspect of this invention relates to a solvent extraction unit suitable for carrying out the method of the first aspect of this invention. The solvent extraction apparatus is configured to generate droplets of an aqueous phase within an organic phase. Furthermore, the solvent extraction system includes means for collecting and removing solid matter.
[0021] This invention is based on the discovery that by utilizing an alternative reaction mode that allows for precipitate formation, the amount of water required to remove calcium in solvent extraction methods can be significantly reduced. Current solvent extraction systems cannot tolerate precipitates, thus requiring the calcium component to be held in solution. It has been found that by confining calcium precipitate formation within aqueous droplets, thereby preventing contact between the precipitate and the organic phase, the problem of precipitate accumulation within the extraction system can be avoided.
[0022] Significant advantages are achieved using this invention. It avoids the problems of solvent extraction unit contamination and maintenance downtime caused by accidental precipitation. Furthermore, the profitability of this method is improved because readily available and cost-effective reagents can be used. Sulfuric acid is available at low cost, and its use in current systems requires large amounts of water to prevent gypsum formation in the presence of calcium ions. Therefore, the water consumption in the method and system of this invention can be significantly reduced to approximately 5% of that in conventional methods and systems. Thus, the method and system of this invention provide a more environmentally friendly and economical method for calcium removal in metal recovery processes. Attached Figure Description
[0023] Figure 1 A solvent extraction unit according to at least some embodiments of the present invention is shown.
[0024] Figure 2 A solvent extraction unit according to an advantageous embodiment is shown, wherein the unit is provided with means for recycling the aqueous extraction solution.
[0025] exist Figure 1 and 2 In the diagram, the aqueous phase is represented by a slash (A), while the organic phase is represented by a white area (B) within the equipment. The aqueous phase droplets are collected into the aqueous layer at the bottom of the solvent extraction unit, also shown by a slash. The horizontal dashed line shows the division between the upper portion of the aqueous layer (representing the layer guided to any recirculation lines) and the lower portion, including the concentrator section from which the calcium-containing slurry is extracted. This dashed line is illustrative only and does not represent any physical part of the equipment. Similarly, the ratio between the liquid and organic phases can be... Figure 1 and Figure 2 The proportions shown are different, so the positions of the entrance and exit can also be changed. Detailed Implementation
[0026] definition
[0027] In the context of this invention, the term "solvent extraction" includes all kinds of liquid-liquid extraction, in which two liquid phases of different properties interact to enable mass transfer from one phase to the other.
[0028] The functional principle of the solvent extraction system described herein is presented in a vertical extraction system. The distributed aqueous phase travels downwards in a vertical system due to density differences (i.e., by gravity). Therefore, expressions such as “upper” or “upper part” should be understood as the upper half of the system or the upper half of the relevant section (layer, part, etc.) when viewed from ground level. Correspondingly, “bottom” or “bottom section” should be understood as the lower half of the system or the lower half of the relevant section when viewed from ground level.
[0029] This invention relates to a solvent extraction method for removing calcium, wherein an aqueous extraction solution is dispensed into an organic phase with a lower density than the aqueous extraction solution. The method includes the following steps:
[0030] - Droplets of the aqueous extraction solution are distributed in the upper part of the solvent extraction unit, wherein the diameter of the distributed droplets is 0.1 mm to 2 mm, preferably 0.5 mm to 2 mm.
[0031] - The droplets are guided through the organic phase toward the bottom of the solvent extraction unit, where they are collected into the aqueous phase layer.
[0032] - At the bottom of the solvent extraction unit, the aqueous slurry containing precipitated calcium compounds is removed from the bottom portion of the aqueous phase layer.
[0033] In this solvent extraction method, calcium is transferred to an aqueous extraction solution. The extraction solution contains counterions capable of forming precipitates with calcium; preferably, the extraction solution is acidic, and even more preferably, an aqueous solution of sulfuric acid. The aqueous solution passes through a calcium-containing organic phase in the form of droplets. The organic phase may contain, for example, an organophosphorus-based extractant, such as commercial reagents D2EHPA or Cyanex 272, or C9-C10 carboxylic acids, but is not limited thereto. Because the density of the aqueous droplets is higher than that of the surrounding organic medium, the droplets travel downwards under gravity. Calcium is transferred to the saturated aqueous extraction solution, and then, through reaction with counterions present in the aqueous extraction solution, the calcium compound precipitates within the droplets. The aim is to achieve controlled precipitation of the calcium compound within the droplets, such that the precipitate is transferred together within the droplets to an aqueous phase layer formed by collecting the droplets at the bottom of the solvent extraction unit. The precipitate settles in a concentrator section at the bottom of the solvent extraction unit, and can be removed from this concentrator section in the form of a slurry, i.e., a suspension containing the precipitated calcium compound. Because calcium is allowed to precipitate during the reaction, there is no need to add water to maintain the concentration of calcium compounds below the solubility equilibrium point. Therefore, this method significantly reduces water consumption compared to currently used methods. When sulfuric acid is used in the extraction solution, water consumption has been found to be as low as 3-7% of that of corresponding conventional methods.
[0034] In a preferred embodiment, the aqueous extraction solution is recycled from the aqueous phase layer at the bottom of the solvent extraction unit to the droplet distribution stage at the top of the solvent extraction unit, wherein makeup water is added to the recycled aqueous extraction solution before droplet distribution. This further reduces water consumption. When using an acidic extraction solution, the acid can be added to the makeup water. The volume ratio of the aqueous phase to the organic phase is typically kept constant in the extraction system and can be, for example, 1:1 to 1:10, preferably 1:2 to 1:10, 1:2 to 1:5, or 2:3 to 1:3. Fluctuations within a predetermined range are permissible, for example, an increase or decrease in the volume of the aqueous phase of up to 10% or up to 20%. By keeping the volume ratio substantially constant, fluid circulation also becomes more reliable because phase mixing can be avoided. When a reagent (e.g., sulfuric acid) is added to the extraction solution to maintain a counterion concentration at a certain level, the amount of reagent added can also remain constant while the volume ratio and composition of the two phases remain constant.
[0035] To avoid phase mixing and unwanted solids being transferred into the recirculation line, the circulating water outlet is optimally positioned at a level close to the interface between the organic and aqueous phase layers, while still ensuring that the outlet of the circulating solution is always in complete contact with only the aqueous phase during operation. This means that the distance between the extract solution outlet and the interface between the aqueous and organic phases should be large enough to allow the volume of the aqueous layer to decrease within a predetermined range of fluctuation, while the extract solution outlet does not contact the organic phase. In this way, water is guided from the upper portion of the aqueous phase layer within the solvent extraction unit to the circulation.
[0036] Since the acidic extraction solution is neutralized upon reaction with calcium, acid can be added to the makeup water to maintain the pH of the extraction solution or its ion concentration at a substantially constant level, for example, within ±15% of a predetermined or initial value. Preferably, the volume ratio of the recycled aqueous extraction solution to the makeup water is 1:1 to 20:1, or even more preferably 5:1 to 20:1. Therefore, the volume of the recycled aqueous solution is 1 to 20 times the volume of the fresh water (i.e., makeup water) added to the method.
[0037] The droplets formed in the droplet distribution step should be large enough to travel efficiently through the organic phase and serve as a precipitation environment for calcium compounds. Precipitation begins when calcium is transferred from the calcium-supported organic phase to droplets containing counterions (such as sulfate ions) in the aqueous extraction solution. When droplets are allowed to fall through the organic phase due to density differences, the formed precipitate will remain within the droplets, provided there is no mixing or only moderate mixing. If the droplets are atomized into a mist of water droplets, each individual droplet will not provide a sufficiently large volume for precipitation to occur if the precipitate itself does not come into contact with the surrounding organic phase. Furthermore, such small droplets move very slowly in the organic phase. On the other hand, droplets that are too large will negatively impact the mass transfer of calcium ions from the organic phase to the aqueous extraction solution because the relative contact surface area between the phases is reduced. To achieve the desired effect, a suitable diameter for the droplets distributed in the upper part of the solvent extraction unit is 0.1 mm to 2 mm, preferably 0.5 mm to 2 mm. Such droplets can be formed, for example, by a nozzle arrangement preferably including multiple nozzles, or by a dispensing system including multiple openings that allow droplets of the desired size to form within the organic solvent used. Therefore, the resulting droplets are relatively small, but still larger than those formed by a turbine.
[0038] In the optimal system, the droplets of the aqueous extraction solution substantially maintain their initial size as they travel through the organic phase toward the aqueous phase layer at the bottom of the solvent extraction unit. This can be achieved without mixing, or with only moderate mixing corresponding to a mixing tip velocity of at most 1 m / s, preferably at most 0.5 m / s. In yet another preferred embodiment, the droplet diameter is 0.1 mm to 2 mm, preferably 0.5 mm to 2 mm, when reaching the aqueous phase layer at the bottom of the solvent extraction unit.
[0039] In another embodiment of this disclosure, droplets are distributed via an extraction solution distributor positioned at a level below the organic solvent outlet in the horizontal direction of the solvent extraction unit. In the aforementioned embodiment, the distribution device guides the droplets downwards into the organic phase, covering an area of at least 70% of the total horizontal cross-sectional area of the solvent extraction unit 1, preferably at least 85% of the total horizontal cross-sectional area of the solvent extraction unit 1, and even more preferably at least 95% of the total horizontal cross-sectional area of the solvent extraction unit 1. This ensures a uniform distribution of droplets in the organic phase.
[0040] In a particularly preferred embodiment of this disclosure, the acidic aqueous phase contains sulfuric acid (H₂SO₄). Sulfate ions react with calcium to form gypsum, thus the calcium-precipitating compound in the aqueous slurry is gypsum (CaSO₄). (2H₂O). Sulfuric acid is the cheapest available inorganic acid, making its use in solvent extraction processes highly advantageous. This might be impossible in conventional systems that cannot tolerate precipitation, or would require the addition of large amounts of water to retain the formed calcium sulfate in solution. In short, the ability to utilize sulfuric acid in the method disclosed herein increases the profitability of the method.
[0041] Calcium precipitates formed in the aqueous droplets are transferred to the bottom of the solvent extraction unit, which preferably serves as a concentrator to guide solids to the bottom of the solvent extraction unit. The aqueous slurry containing the precipitated calcium compounds is removed through a slurry outlet at the bottom of the unit, preferably from the lowest section of the concentrator. The solids content can be, for example, 10, 15, or 20% to 25, 30, or 40%. According to one embodiment of this disclosure, the solids content of the aqueous slurry containing the precipitated calcium compounds removed from the solvent extraction unit is 10-60%, for example, 10-40% or 10-20%. Aqueous gypsum slurries can be removed relatively easily even at higher solids contents.
[0042] In the steps of collecting precipitates and removing slurry, the adhesion of calcium precipitates to the inner surfaces of the equipment can be problematic, especially in the case of gypsum. Therefore, it is preferable to coat at least the bottom of the solvent extraction unit (which is in contact with the collected aqueous phase and calcium precipitate slurry) with a surface-friction-reducing agent, such as a polymer coating, for example a fluoropolymer coating, such as a polyvinylidene fluoride (PVDF), perfluoroalkoxyalkane (PFA), or polytetrafluoroethylene (PTFE) coating. For the same reason, it is advantageous to design the solvent extraction unit such that the shape of the bottom section of the solvent extraction unit directs the flow towards the slurry outlet. To protect the pump lines from blockage and wear, it is advantageous to arrange guide plates connected to the slurry outlet lines to guide solids away from any pumps connected to the concentrator section.
[0043] As described above, it is best to keep the droplets of the aqueous solution intact as they move toward the bottom of the solvent extraction unit. To achieve this, it is preferable to carry out the method without mixing. Alternatively, moderate mixing can be performed such that the mixing does not break the droplets formed at the top into smaller droplets. Naturally, in the method of this disclosure, any such gentle mixing or agitation can be carried out by any mixing method known in the art, for example by using one or more mixing blades rotating at low speed or by the direction of liquid flow. In a preferred embodiment, any mechanical mixing is carried out using a tip speed of at most 1 m / s, preferably at most 0.5 m / s. This is a very low mixing rate compared to the mixing rate of, for example, 5 m / s used in conventional solvent extraction units designed to achieve the highest possible (e.g., >98%) stage efficiency. In conventional units, a mixing rate of about 5 m / s can be applied to increase the contact surface between the two phases, thereby making mass transfer more efficient, while a mixing rate in a similar range in the system of this disclosure would break the droplets of the aqueous extraction solution into smaller droplets, thereby increasing the risk of precipitate contacting the organic phase. Therefore, the precipitate is also more likely to contact the organic phase. When using this conventional mixing method, a problem arises where calcium precipitates form on the inner surface of the unit. Similarly, when the aqueous droplets remain intact, the amount of organic phase lost during the extraction stage is minimized.
[0044] When no mixing or only moderate mixing is applied, the stage efficiency decreases. However, unlike extraction systems used for metal recovery (i.e., production extraction), it has been found that in the system of this disclosure, the primary objective is to remove calcium that may cause problems later in the process, where a relatively low stage efficiency of 10-50% or even 10-20% is sufficient. It is not necessary to remove all calcium in a single process stage, as long as the accumulation of calcium contained in the organic phase is not allowed. The lower stage efficiency can also be compensated for by internal circulation within the aqueous phase.
[0045] This utility model also relates to a solvent extraction unit 1, which has an aqueous extraction solution inlet 3 and an organic solvent outlet 7 at its upper part. Furthermore, the solvent extraction unit 1 includes:
[0046] - An extraction solution dispenser 2, located below the level of the organic solvent outlet 7, is configured to dispense the aqueous extraction solution from the inlet 3 into the organic phase in the form of aqueous droplets 4.
[0047] - Organic solvent inlet 6, located at the bottom of solvent extraction unit 1,
[0048] - A concentrator section 8 for collecting precipitate from the bottom of the solvent extraction unit 1, wherein the concentrator section 8 is located at a level below the organic solvent inlet 6 at the bottom of the solvent extraction unit 1, and includes structures for guiding the precipitate toward the bottom of the solvent extraction unit 1, and
[0049] - Connect to the slurry outlet 5 of the concentrator section 8.
[0050] Such solvent extraction units, such as Figure 1 As shown, and suitable for implementing the method of this invention. Compared with prior art solutions, the solvent extraction unit of this invention is configured to allow solid substances, typically in the form of precipitates. When the formation of precipitates is allowed during extraction or extraction, the water feed can be reduced because it is not necessary to adjust the amount of solvent to retain calcium compounds in solution.
[0051] The solids formed in the process are collected in a concentrator located at the bottom of the solvent extraction unit, and the slurry (i.e., a suspension of solids and aqueous solution) is removed from the concentrator through a slurry outlet 5 at the bottom of the solvent extraction unit 1. The concentrator 8 directs the solids to the bottom of the reactor. This is preferably achieved by providing a concentrator with a structure that tapers towards the bottom (e.g., circular or conical). The slurry outlet 5 may be connected to the lowest part of such a concentrator section. The concentrator may include additional structures, such as guide plates, baffles, or shields, that guide the solids in a desired direction, generally towards the bottom of the solvent extraction unit, and / or protect any pumps or additional outlets located in the concentrator section from deposits. Since solid calcium compounds, such as plaster, can easily adhere to the equipment walls, it is preferable to coat any surface with a coating that reduces surface friction. Steel surfaces, in particular, are prone to contamination, where plaster tends to accumulate and block flow connections. By providing this low-friction coating to the inner surfaces of the solvent extraction unit 1, and especially the inner surfaces of the concentrator section 8, the need for system maintenance is reduced, and slurry flow is improved. Different types of low-friction coatings are known in the art. Many polymer coatings, such as polytetrafluoroethylene (PTFE), paints, and linings, are suitable for this purpose.
[0052] In a particularly preferred embodiment of this disclosure, the solvent extraction unit 1 further includes an extraction solution outlet 9 located at the bottom of the solvent extraction unit, below the organic solvent inlet 6 and above the slurry outlet 5, wherein the extraction solution outlet 9 is fluidly connected to the makeup water supply line 10 and the extraction solution inlet 3. The extraction solution outlet 9, fluidly connected to the extraction solution inlet 3, provides the possibility of circulating the aqueous extraction solution, thereby further reducing the system's water consumption. Since at least a portion of the aqueous solution introduced via inlet 3 is removed through the slurry outlet 5, fresh makeup water needs to be introduced to compensate for the aqueous solution removed along with the slurry, thereby maintaining system balance. Makeup water can be introduced via supply line 10, i.e., the makeup water inlet, which is also fluidly connected to the extraction solution inlet 3. An acid or another aqueous solution containing a reactive counterion can be added to the makeup water to maintain the precipitation reaction at the desired level.
[0053] In another embodiment of this disclosure, the extracting solution dispenser 2 includes a plurality of fluid dispensing openings arranged at intervals between each other, wherein the ratio of the distance between two adjacent openings to the diameter of the opening is 2:1 to 20:1, preferably 3:1 to 10:1 or 5:1 to 10:1. Therefore, the distance between the openings is sufficient to form individual droplets, i.e., the droplets are not so close to each other that they would combine, but are still within a range where sufficient efficiency can be achieved. To form droplets of a desired size of 0.1 to 2 mm, the openings can be in a similar range of 0.05 to 2 mm or 0.1 to 2 mm. The arrangement of uniformly distributed droplet openings minimizes the degree of interaction between droplets and maximizes the droplet distribution within the organic phase volume because the droplets are dispersed and generated in a controlled manner.
[0054] In a further preferred embodiment, the extraction solution dispenser 2 extends through at least 70% of the total horizontal cross-sectional area of the solvent extraction unit, preferably at least 85%, and even more preferably at least 95%. Arranging the dispenser allows access to the widest possible area, improving system efficiency. Furthermore, arranging the dispenser ensures that droplets fall vertically, minimizing interactions between surrounding droplets. Compared to point dispensing, such as using a single nozzle system arranged in an area along the vertical central axis of the system, droplets formed in point dispensing are also dispersed horizontally or partially horizontally, making droplet flow more unpredictable. The dispenser system can be arranged such that the organic phase can be dispensed through the dispenser system, for example, through a network of multiple dispensing systems or dispenser openings.
[0055] In another embodiment of this disclosure, the solvent extraction unit (1) does not have a mixing device.
[0056] In another embodiment of this disclosure, the solvent extraction unit (1) has a mechanical mixing device having a tip speed of up to 1 m / s, preferably up to 0.5 m / s.
[0057] It should be understood that the disclosed embodiments of this utility model are not limited to the specific structures, method steps, or materials disclosed herein, but extend to their equivalents that will be recognized by those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.
[0058] Throughout this specification, references to "an embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of the present invention. Therefore, the phrases "in an embodiment" or "in one embodiment" appearing in various places throughout the specification do not necessarily refer to the same embodiment.
[0059] As used herein, for convenience, multiple items, structural elements, constituent elements, and / or materials may be presented in a common list. However, these lists should be interpreted as if each member of the list were individually identified as a separate and unique member. Therefore, without indication to the contrary, no single member of such a list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in the common group. Furthermore, various embodiments and examples of the present invention may be mentioned herein together with alternatives to its various components. It should be understood that such embodiments, examples, and alternatives should not be construed as de facto equivalents of each other, but should be considered as separate and independent representations of the present invention.
[0060] While the foregoing examples illustrate the principles of the present invention in one or more specific applications, it will be apparent to those skilled in the art that numerous modifications in form, use, and implementation details can be made without inventiveness or deviation from the principles and concepts of the present invention. Therefore, the present invention is not intended to be limited to any means other than the following claims.
[0061] The following non-limiting examples are intended only to illustrate the advantages obtained through embodiments of the present invention.
[0062] Example
[0063] Example 1 – Calcium Removal
[0064] 35 m 3An aqueous feed of [amount] h is fed into the solvent extraction method. In the extraction unit, calcium is extracted into the organic phase. The calcium-containing organic phase is then directed to the liquid-liquid extraction step. The aqueous extraction solution is distributed as droplets in the organic solvent, with a volume ratio of aqueous solution to organic solvent of 1:10. The solution is extracted from the bottom of the solvent extraction unit at a rate of 1 m... 3 The gypsum slurry is collected at a flow rate of / h. The gypsum slurry has a solids content of 10%. The aqueous solution is circulated from the bottom of the solvent extraction unit to the inlet at a flow rate of 1m. 3 Add supplemental water at a rate of / h, corresponding to the volume of slurry removed.
[0065] In conventional systems where sedimentation is not permitted, the extraction solution flow rate must equal the aqueous feed flow rate, i.e., 35 m³ / h. 3 / h.
[0066] Industrial applicability
[0067] The method and system of this invention can be used to replace traditional solvent extraction for calcium removal.
[0068] In particular, this method provides a resource-efficient procedure for calcium removal in metal separation processes. The required water volume is only a fraction of that of conventional methods, and the method can also utilize affordable reagents.
[0069] List of reference numerals
[0070] 1. Solvent Extraction Unit
[0071] 2. Extraction solution dispenser
[0072] 3. Extraction solution inlet
[0073] 4. Aqueous droplets (formed in the extractant dispenser)
[0074] 5. Slurry outlet
[0075] 6. Organic solvent inlet
[0076] 7. Organic solvent export
[0077] 8. Concentrator Section
[0078] 9. Extraction solution outlet
[0079] 10. Water supply pipeline
[0080] 11. Extraction solution circulation pump
[0081] Citation List
[0082] Patent documents:
[0083] EP 2614868 B1
[0084] US 2022 / 0332751 A1
Claims
1. A solvent extraction unit (1), having an aqueous extraction solution inlet (3) and an organic solvent outlet (7) at its upper part, characterized in that, The solvent extraction unit (1) further includes: - An extraction solution dispenser (2), located below the level of the organic solvent outlet (7), is configured to dispense the aqueous extraction solution from the aqueous extraction solution inlet (3) into the organic phase in the form of aqueous droplets (4). - Organic solvent inlet (6), which is located at the bottom of solvent extraction unit (1), - A concentrator section (8) for collecting precipitate from the bottom of the solvent extraction unit (1), wherein the concentrator section (8) is located at a level below the organic solvent inlet (6) at the bottom of the solvent extraction unit (1), and includes structures for guiding the precipitate toward the bottom of the solvent extraction unit (1), and - Slurry outlet (5) connected to the concentrator section (8).
2. The solvent extraction unit (1) according to claim 1, characterized in that, The extraction solution dispenser (2) is configured to dispense the aqueous extraction solution in the form of aqueous droplets (4) with a diameter of 0.1 mm to 2 mm.
3. The solvent extraction unit (1) according to claim 2, characterized in that, The diameter of the aqueous droplets (4) ranges from 0.5 mm to 2 mm.
4. The solvent extraction unit (1) according to claim 1 or 2, characterized in that, The solvent extraction unit (1) further includes an extraction solution outlet (9) located at the bottom of the solvent extraction unit, at a level below the organic solvent inlet (6) and above the slurry outlet (5), wherein the extraction solution outlet (9) is fluidly connected to the make-up water supply line (10) and the aqueous extraction solution inlet (3).
5. The solvent extraction unit (1) according to claim 1 or 2, characterized in that, The extraction solution dispenser (2) includes a plurality of fluid dispensing openings arranged at a certain distance from each other, and the ratio of the distance between two adjacent openings to the diameter of the opening is 2:1 - 20:
1.
6. The solvent extraction unit (1) according to claim 5, characterized in that, The ratio of the distance between two adjacent openings to the diameter of the opening is 3:1 - 10:
1.
7. The solvent extraction unit (1) according to claim 1 or 2, characterized in that, The extraction solution dispenser (2) extends through at least 70% of the total horizontal cross-sectional area of the solvent extraction unit.
8. The solvent extraction unit (1) according to claim 7, characterized in that, The extraction solution dispenser (2) extends through at least 85% of the total horizontal cross-sectional area of the solvent extraction unit.
9. The solvent extraction unit (1) according to claim 1 or 2, characterized in that, The concentrator section (8) includes a guide plate arranged to protect any pump connected to the concentrator section (8) from sediment.
10. The solvent extraction unit (1) according to claim 1 or 2, characterized in that, The inner surface of the solvent extraction unit (1) is coated with a polymer coating to prevent precipitates from adhering to the inner surface of the solvent extraction unit (1).
11. The solvent extraction unit (1) according to claim 10, characterized in that, The surface of the concentrator section (8) is coated with a polymer coating to prevent precipitates from adhering to the surface of the concentrator section (8).
12. The solvent extraction unit (1) according to claim 1 or 2, characterized in that, The solvent extraction unit (1) does not have a mixing device.
13. The solvent extraction unit (1) according to claim 1 or 2, characterized in that, The solvent extraction unit (1) has a mechanical mixing device with a tip velocity of up to 1 m / s.
14. The solvent extraction unit (1) according to claim 13, characterized in that, The tip velocity is at most 0.5 m / s.