Design method of linkage extraction separation process for feed liquid with two different components

Abstract

The invention relates to a design method of a linkage extraction separation process of feed liquid with different components and two components, which comprises the following steps: determining feed liquid of an extraction section of a separation unit I, and judging a proportional relation between a first water phase flow and a second water phase flow; if the ratio of the first water phase flow to the second water phase flow is larger than or equal to the optimal matching ratio, the second water phase serves as feeding liquid of an extraction section of a separation unit I, the first part of the first water phase serves as washing liquid to be introduced into the separation unit I, and the second part of the first water phase is separated through a separation unit III; if the ratio of the first water phase flow to the second water phase flow is smaller than the optimal matching ratio, the first part of the second water phase serves as extraction section feed liquid of a separation unit I section, the second part is separated through a separation unit III, and the first water phase serves as washing liquid to be introduced into the separation unit I; and calculating the number of extractors required by each separation section. According to the method, the total acid and alkali consumption in the extraction and separation process is reduced by utilizing the separation work contained in the feed liquid, the production cost is saved, and the salt-containing wastewater generation amount is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of rare earth hydrometallurgy, and particularly relates to a design method for a linkage extraction and separation process of two-component feed liquids with different compositions. Background Art

[0002] The separation of rare earth elements (REEs) is a typical multi-component separation system. The diverse nature of the processes required to achieve solvent extraction separations of up to 15 REEs significantly increases the complexity of process design. In rare earth separation processes using acidic extractants, the organic extractant phase, loaded with the difficult-to-extract rare earth components, and the wash solution containing the easily extractable rare earth components provide the "separation work" for the extraction and washing processes, respectively. The alkali consumed in the saponification / rare earth soap process and the acid consumed in the stripping / washing process provide both separation work and are the primary source of saline wastewater, a significant factor impacting production costs. Therefore, continuously reducing acid and alkali consumption during rare earth extraction and separation processes has always been a key driver of process evolution and optimization.

[0003] Linked extraction and separation technology (see: Development History and Recent Advances in Cascade Extraction Theory, Journal of the Chinese Rare Earth Society, 2017, 35(1):1-8) has become a fundamental technology in my country's rare earth separation industry due to its significant energy consumption and emission reduction capabilities. The invention patent, "A Multi-Component Linked Extraction and Separation Process Design System and Method" (Patent No. ZL201810183244.6), provides a multi-component linked extraction and separation process design system that reduces the workload of determining optimized process parameters during process design for a multi-component linked extraction and separation process, and provides sufficient basis for accurately determining the theoretical minimum extraction and minimum washing volumes that represent acid and alkali consumption levels. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a design method for a linked extraction and separation process for two-component liquids with different compositions. The method aims to minimize the theoretical minimum extraction amount and minimum washing amount required to separate the two components in the two liquids through the optimized design of the combined separation method for two-component aqueous liquids with the same component but different composition, thereby reducing the acid and alkali consumption of the overall separation process, reducing production costs and the amount of salt-containing wastewater generated.

[0005] To achieve the above objectives, the present invention adopts a technical solution: a method for designing a linked extraction separation process for two components of liquid feed with different compositions, the method comprising the following steps:

[0006] S1. Determine the feed liquid for the extraction section of separation unit I: separation unit I includes an extraction section of separation unit I and a washing section of separation unit I. The first aqueous phase and the second aqueous phase undergoing linked extraction and separation both contain components A and B. The molar percentage of the easily extractable component in the second aqueous phase is lower than that in the first aqueous phase. Use all or part of the second aqueous phase as the feed liquid for the extraction section of separation unit I;

[0007] S2, determine the first water phase flow rate (f a )1 and the second aqueous phase flow rate (f a )2 numerical proportional relationship:

[0008] Calculate the first water phase flow rate (f a )1 and the second water phase flow rate (f a )2's best matching ratio;

[0009] If the first aqueous phase flow rate (f a )1 and the second water phase flow rate (f a )2 actual ratio ≥ the best matching ratio, then go to step S3; if the first water phase flow rate (f a )1 and the second water phase flow rate (f a )2's actual ratio is less than the best matching ratio, then proceed to step S4;

[0010] S3, the entire second aqueous phase is used as the feed liquid for the extraction section of the separation unit I for extraction and separation; and the first aqueous phase is split into two parts:

[0011] (f a )1=(f a )′1+(f a )″1 (6)

[0012] Wherein, the flow rate of the first part in the first aqueous phase is (f a )′1, is introduced as washing liquid from the kth stage of the washing section of the separation unit I, which is linked with the second aqueous phase; the flow rate of the second part in the first aqueous phase is (f a )″1, separation treatment is carried out using separation unit III; the organic phase flowing out of the k-stage washing section of separation unit I is drawn out and introduced into separation unit II, and further separated as the feed liquid of separation unit II;

[0013] S4, using part of the second aqueous phase as the feed liquid for the extraction section of the separation unit I for extraction separation; that is, splitting the second aqueous phase into two parts:

[0014] (f a )2=(f a )′2+(f a )″2

[0015] The flow rate of the first part of the second aqueous phase is (fa )′2, the extraction section of the separation unit I is introduced as the feed liquid of the separation unit I, and the first aqueous phase is introduced as the washing liquid from the jth stage of the washing section of the separation unit I; the flow rate of the second part of the second aqueous phase is (f a )″2, separation treatment is carried out using separation unit III; the organic phase flowing out of the j-stage washing section of separation unit I is drawn out and introduced into separation unit II to continue separation as the feed liquid of separation unit II;

[0016] S5. Use the static recursive method to calculate the number of extractor stages required for each separation stage.

[0017] Furthermore, A is a relatively easy-to-extract component and B is a relatively difficult-to-extract component; the molar percentages of components A and B in the first aqueous phase are (p A )1 and (p B )1, the molar percentages of components A and B in the second aqueous phase are (p A )2 and (p B )2, and (p A )1>(p A )2,(p B )1<(p B )2;

[0018] The fractional flow rates of components A and B in the first aqueous phase are (f A )1=(f a )1(p A )1,(f B )1=(f a )1(p B )1; the fractional flow rates of components A and B in the second aqueous phase are (f A )2=(f a )2(p A )2,

[0019] (f B )2=(f a )2(p B )2.

[0020] Further, the first water phase flow rate (f a )1 and the second aqueous phase flow rate (f a )2's best matching ratio:

[0021]

[0022] Among them, β is the separation coefficient between components A and B.

[0023] Further, in step S3, (f a )′1 satisfies the following formula:

[0024]

[0025] Furthermore, in step S3, the method for determining the kth stage of the washing section of the separation unit I is as follows: when the molar percentages of components A and B in the aqueous phase of the kth stage of the washing section of the separation unit I are exactly the same as or most similar to those of the first aqueous phase to be separated, the first portion of the first aqueous phase is introduced from the kth stage of the washing section of the separation unit I as the washing liquid.

[0026] Further, in step S3, the minimum extraction amount (S min ) I and minimum washing volume (W min ) I Calculate as follows:

[0027]

[0028] In step S3, the organic phase flow rate y drawn from the washing section k of the separation unit I is k for:

[0029] y k =(S min ) i (10)

[0030] The flow rate x of the first part of the first aqueous phase introduced from the kth stage of the washing section of the separation unit I k for:

[0031] x k =(W min ) I =(f a )′1 (11).

[0032] Further, in step S3, the minimum extraction amount (S min ) II and minimum washing volume (W min ) II Calculate as follows:

[0033]

[0034] Further, in step S3, the minimum extraction amount (S min ) III and minimum washing volume (W min ) III Calculate as follows:

[0035]

[0036] Further, in step S4, (f a )′2 satisfies the following formula:

[0037]

[0038] Where β is the separation coefficient between components A and B;

[0039] The method for determining the jth stage of the washing section of separation unit I is as follows: when the molar percentages of components A and B in the aqueous phase of the jth stage of the washing section of separation unit I are exactly the same as or most similar to those of the first aqueous phase to be separated, the entire first aqueous phase is introduced from the jth stage of the washing section of separation unit I as the washing liquid.

[0040] Further, in step S4, the minimum extraction amount (S min ) I and minimum washing volume (W min ) I Calculate as follows:

[0041]

[0042] In step S4, the organic phase flow rate y drawn from the jth stage of the washing section of the separation unit I is j for:

[0043] y j =(S min ) I (twenty four)

[0044] The flow rate of the first aqueous phase introduced from the jth stage of the washing section of the separation unit I is x j for:

[0045] x j =(f a )1 (25).

[0046] Further, in step S4, the minimum extraction amount (S min ) II and minimum washing volume (W min ) II Calculate as follows:

[0047]

[0048] Further, in step S4, the minimum extraction amount (S min ) III and minimum washing volume (W min ) III Calculate as follows:

[0049]

[0050] Furthermore, in step S5, the number of extractor stages required for each separation unit is recursively calculated starting from the left and right ends of each separation unit according to the extraction balance and material balance relationship of the materials in each extraction and separation unit;

[0051] In the extraction section of each separation unit, the aqueous phase outlet at the left end is component B, and the organic phase inlet is calculated as a blank extractant; in the washing section of each separation unit, when the organic phase outlet at the right end contains only component A, the aqueous phase inlet is calculated as a blank washing liquid; when the organic phase outlet at the right end contains both components A and B, the aqueous phase inlet introduces the first aqueous phase feed liquid.

[0052] Further, in step S5, the flow rate of component A as an impurity in the left outlet of separation unit I, separation unit II or separation unit III is set to x A,1 =ε A ·x B,1 ; Set the flow rate of component B as an impurity in the right outlet of separation unit II or separation unit III to y B,n+m =ε B ·y A,n+m ; Among them, ε A , ε B Determined according to the rare earth purity of products A and B, ε A =1-B product rare earth purity, ε B =1-A product rare earth purity;

[0053] When the first stage at the right end of the separation unit I is the kth stage, the split flow of the two components in the aqueous phase introduced from this stage is calculated as follows:

[0054] x A,k =(f a )′1·(p A )1 (38)

[0055] x B,k =(f a )′1·(p B )1 (39)

[0056] The split flow of the two components in the organic phase flowing out of the kth stage is calculated according to the following two formulas:

[0057] y A,k =(f a )′1·(p A )1+(f a )2·(p A )2 (40)

[0058] y B,k =(f a )′1·(p B )1 (41)

[0059] When the first stage at the right end of the separation unit I is the jth stage, the split flow of the two components in the aqueous phase introduced from the jth stage is calculated as follows:

[0060] x A,j =(f a )1·(p A )1 (42)

[0061] x B,j =(f a )1·(p B )1 (43)

[0062] The split flow of the two components in the organic phase flowing out of this stage is calculated according to the following two formulas:

[0063] y A,j =(f a )1·(p A )1+(f a )′2·(p A )2 (44)

[0064] y B,j =(f a )1·(p B )1 (45).

[0065] The beneficial effect of the present invention is that: the design method of the linkage extraction separation process of the two-component feed liquid with different compositions provided by the present invention comprises the following steps: determining that the feed liquid of the extraction section of the separation unit I is the second aqueous phase with a lower molar percentage content of the easily extractable component, judging the flow rate of the first aqueous phase (f a )1 and the second aqueous phase flow rate (f a )2. If the first water phase flow rate (f a )1 and the second water phase flow rate (f a )2 actual ratio ≥ optimal matching ratio, the entire second aqueous phase is used as the feed liquid of the extraction section of the separation unit I for extraction separation; and the first aqueous phase is split into two parts, and the flow rate of the first part of the first aqueous phase is (f a )′1, is introduced as washing liquid from the kth stage of the washing section of the separation unit I, which is linked with the second aqueous phase; the flow rate of the second part in the first aqueous phase is (f a ) "1", separation unit III is used for separation treatment; the organic phase flowing out from the k-stage washing section of separation unit I is drawn out and introduced into separation unit II as the feed liquid of separation unit II for further separation. If the first aqueous phase flow rate (f a )1 and the second water phase flow rate (f a )2 actual ratio < optimal matching ratio, part of the second aqueous phase is used as the feed liquid of the extraction section of the separation unit I for extraction separation; that is, the second aqueous phase is split into two parts; the flow rate of the first part of the second aqueous phase is (fa )′2, the extraction section of the separation unit I is introduced as the feed liquid of the separation unit I, and the first aqueous phase is introduced as the washing liquid from the jth stage of the washing section of the separation unit I; the flow rate of the second part of the second aqueous phase is (f a )″2, separation treatment is carried out using separation unit III; the organic phase flowing out of stage k of the washing section of separation unit I is withdrawn and introduced into separation unit II to continue separation as the feed liquid of separation unit II. Finally, the static recursive method is used to calculate the number of extractor stages required for each separation section.

[0066] The present invention provides a design method for a linked extraction and separation process for two-component feed liquids of different compositions. For a two-component rare earth separation system, a linked extraction and separation process using two aqueous phase feed liquids containing the same components but different compositions is employed. This process fully utilizes the separation power inherent in the feed liquids themselves and, through a rational combined separation process design, achieves an extraction amount and a washing amount lower than the theoretical minimum required for separating the two feed liquids individually or directly mixing them for separation. This reduces the total acid and alkali consumption during the extraction and separation process, saves production costs, and reduces the amount of saline wastewater generated. This method addresses the problem of a lack of relevant process optimization design for the extraction and separation of feed liquids containing the same components but different compositions in actual extraction and separation industrial production processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 1. It is a schematic flow chart of a design method for a linked extraction and separation process of two-component feed liquids of different compositions when the actual ratio of the first aqueous phase flow rate to the second aqueous phase flow rate is ≥ the optimal matching ratio according to an embodiment of the present invention;

[0068] Figure 2 1. It is a schematic flow chart of a design method for a linked extraction and separation process of two-component feed liquids of different compositions when the actual ratio of the first aqueous phase flow rate to the second aqueous phase flow rate is less than the optimal matching ratio according to an embodiment of the present invention;

[0069] Figure 3 This is a schematic flow chart of a design method for a linked extraction and separation process for two-component feed liquids of different compositions as described in Example 1 of the present invention;

[0070] Figure 4 It is a schematic flow chart of a design method for a linked extraction and separation process of two-component liquid feeds of different compositions as described in Example 2 of the present invention. DETAILED DESCRIPTION

[0071] The technical solutions in the embodiments of the present invention will be further clearly and completely described below in conjunction with the drawings and examples. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0072] It should be noted that, in the description of the embodiments of the present invention, terms such as "horizontal", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the present invention.

[0073] In the industrial production process of rare earth extraction and separation, different process sections often produce rare earth solutions or organic phases containing the same components but different compositions that need to be further separated. In addition, rare earth separation companies also have the need to design a combined linkage extraction and separation process for raw materials with different compositions from different sources. In actual production processes, for feed liquids with the same components but different compositions, they are usually extracted and separated separately or directly mixed, but there is a lack of a more efficient method for designing a linkage extraction and separation process between raw materials with the same components but different compositions. To this end, this embodiment proposes an extraction and separation process and its design method for a two-component rare earth separation system that minimizes the theoretical minimum extraction amount and the minimum washing amount required for two-component aqueous phase feed liquids with the same components but different compositions.

[0074] This embodiment provides a design method for a linkage extraction and separation process for two-component feed liquids of different compositions. The two aqueous phase feed liquids subjected to linkage extraction and separation are respectively recorded as a first aqueous phase 1 and a second aqueous phase 2, both containing two components A and B, wherein A is a relatively easy-to-extract component and B is a relatively difficult-to-extract component; the distribution (or molar percentage) of the two components in the first aqueous phase 1 is (p A )1 and (p B )1, the total flow is (f a )1, then the fractional flow of the two components in the first aqueous phase 1 (f A )1=(f a )1(p A )1,(f B )1=(f a )1(p B )1; the distribution of the two components in the second aqueous phase 2 is (p A )2 and (p B )2, the total flow is (f a)2, then the fractional flow of the two components in the second aqueous phase 2 (f A )2=(f a )2(p A )2,(f B )2=(f a )2(p B )2; and

[0075] (p A )1>(p A )2,(p B )1<(p B )2.

[0076] The minimum total extraction volume required to separate two aqueous phase liquids separately or to mix the two aqueous phase liquids directly and then separate them and minimum washing volume They are respectively:

[0077]

[0078] In formula (1) and (2), β is the separation coefficient of components A and B.

[0079] like Figure 1-2 As shown, the main scheme of the process design is that the second aqueous phase 2 containing a lower percentage of easily extractable components is used as the feed liquid in the extraction section of the separation unit I. When the distribution of the two components in the aqueous phase of a certain level (such as the kth level) of the washing section of the separation unit I is exactly the same as or most similar to the first aqueous phase 1 to be separated, the first aqueous phase 1 is introduced from the washing section, and the organic phase flowing out from the kth level is simultaneously drawn out and used as the feed liquid for the separation unit II to continue separation.

[0080] In order to reduce the total minimum extraction amount and the total minimum washing amount in the separation process of the two aqueous phase feed liquid, this embodiment provides a design method for a linked extraction separation process of two components of feed liquid with different compositions. The linked extraction process flow is designed according to the following steps:

[0081] S1. Determining the feed liquid for the extraction section of separation unit I: separation unit I includes an extraction section of separation unit I and a washing section of separation unit I, wherein all or part of the second aqueous phase 2 containing a relatively low molar percentage of easily extractable components is used as the feed liquid for the extraction section of separation unit I for extraction and separation;

[0082] Specifically, the first aqueous phase 1 and the second aqueous phase 2 for linkage extraction separation both contain two components, A and B, wherein A is the easier-to-extract component and B is the harder-to-extract component (i.e., A is the easier-to-extract component relative to B); the molar percentages of components A and B in the first aqueous phase 1 are (p A )1 and (p B )1, the molar percentages of components A and B in the second aqueous phase 2 are (p A)2 and (p B )2, and (p A )1>(p A )2,(p B )1<(p B )2.

[0083] Among them, the total flow rate of the first aqueous phase 1 is (f a )1, then the fractional flow rates of components A and B in the first aqueous phase 1 are (f A )1=(f a )1(p A )1,(f B )1=(f a )1(p B )1; the total flow rate of the second aqueous phase 2 is (f a )2, then the fractional flow rates of components A and B in the second aqueous phase 2 are (f A )2=(f a )2(p A )2,

[0084] (f B )2=(f a )2(p B )2.

[0085] S2, determine the flow rate of the first water phase 1 (f a )1 and the flow rate of the second aqueous phase 2 (f a )2 numerical proportional relationship;

[0086] S21, first determine the flow rate of the first aqueous phase 1 (f a )1 and the flow rate of the second aqueous phase 2 (f a )2, the first water phase 1 flow rate (f a )1 and the flow rate of the second aqueous phase 2 (f a )2's best matching ratio:

[0087]

[0088] Wherein, β is the separation coefficient of the two components A and B; when formula (3) holds true, the flow rate of the first aqueous phase 1 introduced into the washing unit of separation unit I should be exactly equal to the minimum washing amount required for separation of the second aqueous phase 2 of separation unit I.

[0089] S22. According to the numerical relationship between the actual flow rates of the first aqueous phase 1 and the second aqueous phase 2, there are the following two situations:

[0090]

[0091] S3. If formula (4) holds true, the first water phase flow rate (fa )1 and the second water phase flow rate (f a )2's actual ratio ≥ the best matching ratio, such as Figure 1 As shown, the entire second aqueous phase 2 is used as the feed liquid for the nth stage (the rightmost stage) of the extraction section of the separation unit I for extraction and separation; and the first aqueous phase 1 is split into two parts, so that:

[0092] (f a )1=(f a )′1+(f a )″1 (6)

[0093] Among them, the flow rate of the first part in the first aqueous phase 1 is (f a )′1, which is linked to the second aqueous phase 2 and introduced as washing liquid from the kth stage of the washing section of the separation unit I; the flow rate of the second part of the first aqueous phase 1 is (f a )″1, separate separation is performed using a separate separation unit III. a )′1 satisfies the following formula:

[0094]

[0095] Optionally, in step S3, the method for determining the kth stage of the washing section of the separation unit I is: when the molar percentages of components A and B in the aqueous phase of the kth stage of the washing section of the separation unit I are exactly the same as or most similar to those of the first aqueous phase 1 to be separated, the first part of the first aqueous phase 1 is introduced from the kth stage of the washing section of the separation unit I (the rightmost stage of the washing section of the separation unit I) as the washing liquid.

[0096] Optionally, the minimum extraction amount (S min ) I and minimum washing volume (W min ) I Calculate as follows:

[0097]

[0098] In formula (8) and (9), the fractional flow rate of component A in the second aqueous phase 2 (f A )2=(f a )2(p A )2,(p A )2 is the distribution (or molar percentage) of component A in the second aqueous phase 2. The fractional flow rate (f B )2=(f a )2(p B )2,(p B )2 is the distribution (or molar percentage) of component B in the second aqueous phase 2.

[0099] In step S3, the organic phase flowing out from the k-stage washing section of separation unit I is drawn out and introduced into separation unit II to continue separation as the feed liquid of separation unit II; the flow rate of the organic phase drawn out from the k-stage washing section of separation unit I is y k (Introduced into separation unit II as separation unit II feed liquid) is:

[0100] y k =(S min ) I (10)

[0101] The flow rate x of the first part of the first aqueous phase 1 introduced from the kth stage of the washing section of the separation unit I k for:

[0102] x k =(W min ) I =(f a )′1 (11)

[0103] Optionally, the minimum extraction volume (S min ) II and minimum washing volume (W min ) II Calculate as follows:

[0104]

[0105] In formula (12) and (13), the fractional flow rate of component A in the second aqueous phase 2 (f A )2=(f a )2(p A )2,(p A )2 is the distribution (or molar percentage) of component A in the second aqueous phase 2; (f a )′1 is calculated using formula (7). (p A )1 is the molar percentage of component A in the first aqueous phase 1, (p B )1 is the distribution (or molar percentage) of component B in the first aqueous phase 1.

[0106] Optionally, the minimum extraction amount (S min ) III and minimum washing volume (W min ) III Calculate as follows:

[0107]

[0108] In formula (14) and (15), the minimum extraction amount (S min ) Iand minimum washing volume (W min ) I Calculate according to formula (8) and (9); the flow rate of the first part of the first aqueous phase 1 (f a )1. The flow rate of the second part in the first aqueous phase 1 (f a )″1 is calculated according to formula (6) and (7) respectively.

[0109] Since the washing amount of the separation unit 1 is provided by the first aqueous phase 1, it does not need to be calculated separately. Therefore, the total minimum extraction amount S of the three separation units is min and minimum washing volume W min Calculate according to the following two formulas:

[0110]

[0111] Compared with separating two liquids separately or mixing two liquids directly and then separating them, the minimum extraction amount ΔS is reduced min and minimum washing volume ΔW min They are:

[0112] ΔS min =(f a )′1[(p A )1-(p A )2] (18)

[0113] ΔW min =(f a )′1[(p B )2-(p B )1] (19)

[0114] S4. If formula (5) holds true, the first water phase flow rate (f a )1 and the second water phase flow rate (f a )2's actual ratio is less than the best matching ratio, such as Figure 2 As shown, part of the second aqueous phase 2 is used as the feed liquid of the extraction section of the separation unit I for extraction and separation; that is, the second aqueous phase 2 is split into two parts, and the following is made:

[0115] (f a )2=(f a )′2+(f a )″2 (20)

[0116] The flow rate of the first part of the second aqueous phase 2 is (f a )′2, the nth stage of the extraction section of the separation unit I is introduced as the feed liquid of the separation unit I, and the first aqueous phase 1 is introduced as the washing liquid from the jth stage of the washing section of the separation unit I; the flow rate of the second part of the second aqueous phase 2 is (f a )″2, the feed liquid of separation unit III is separated and processed separately, and the process flow is as follows Figure 2 As shown. Where (f a )′2 satisfies the following formula:

[0117]

[0118] Optionally, in step S4, the method for determining the j-th stage of the washing section of separation unit I is the same as that in step S3: when the molar percentages of components A and B in the j-th stage aqueous phase of the washing section of separation unit I are exactly the same as or most similar to those of the first aqueous phase 1 to be separated, all the first aqueous phase is introduced from the j-th stage of the washing section of separation unit I as the washing liquid.

[0119] In step S4, the minimum extraction amount (S min ) I and minimum washing volume (W min ) I Calculate as follows:

[0120]

[0121] In step S4, the organic phase flowing out from the jth stage of the washing section of separation unit I is drawn out and introduced into separation unit II to continue separation as the feed liquid of separation unit II; the flow rate of the organic phase drawn out from the jth stage of the washing section of separation unit I is y j (Introducing separation unit II as separation unit II feed liquid) is still:

[0122] y j =(S min ) I (twenty four)

[0123] The flow rate x of the first aqueous phase 1 introduced from the jth stage of the washing section of the separation unit I j for:

[0124] x j =(f a )1 (25)

[0125] Minimum extraction volume of separation unit II (S min ) II and minimum washing volume (W min ) II Calculate as follows:

[0126]

[0127] Minimum extraction volume of separation unit III (S min ) IlI and minimum washing volume (W min ) III Calculate as follows:

[0128]

[0129] The washing amount of the separation unit I is provided by the first aqueous phase I, so the total minimum extraction amount S of the three separation units is min and minimum washing volume W min Calculate according to the following two formulas:

[0130]

[0131] Compared with separating two liquids separately or mixing two liquids directly and then separating them, the minimum extraction amount ΔS is reduced min and minimum washing volume ΔW min They are:

[0132] ΔS min =(f a )1[(p A )1-(p A )2] (32)

[0133] ΔW min =(f a )1[(p B )2-(p B )1] (33)

[0134] S5. Use the static recursive method to calculate the number of extractor stages required for each separation stage.

[0135] Based on the extraction balance and material balance relationship of the materials in each extraction and separation unit, the number of extractor stages required for each separation unit is recursively calculated, starting from the left and right ends of each separation unit. In the extraction section of each separation unit, the left-end aqueous phase outlet is component B, and the organic phase inlet is calculated based on blank extractant. In the washing section of each separation unit, when the right-end organic phase outlet contains only component A, the aqueous phase inlet is calculated based on blank washing liquid. When the right-end organic phase outlet contains both components A and B, the aqueous phase inlet introduces the first aqueous phase feed liquid.

[0136] In the actual separation process of step S5, the product has a certain purity, and the flow rate of component A as an impurity in the left outlet of separation unit I, separation unit II or separation unit III can be set to x A,1 =

[0137] ε A ·x B,1 ; Set the flow rate of component B as an impurity in the right outlet of separation unit II or separation unit III to y B,n+m =ε B ·y A,n+m ; Among them, ε A , ε B Determined according to the rare earth purity of products A and B, ε A =1-B product rare earth purity, ε B=1-rare earth purity of product A. In a specific embodiment, the purity of the rare earth of the final products A and B must reach 99.99%, then ε A =ε B =0.0001.

[0138] Specifically, for the extraction section of separation unit I, separation unit II or separation unit III, the flow rates x of components A and B at the aqueous phase outlet are known. A,1 and x B,1 , from the material balance and extraction balance of the first stage of the extraction section of the separation unit where the water phase outlet is located, it can be seen that:

[0139]

[0140] Solving the above equations, we can get a set of y values ​​for the first stage of the extraction section of separation unit I, separation unit II or separation unit III: A,1 and y B,1 The solution is then used to obtain the water phase flow rate of each component flowing out of the second stage from the following material transfer balance:

[0141]

[0142] Among them, f B It is the flow rate of component B in the aqueous phase feed liquid of the extraction section of separation unit I, separation unit II or separation unit III.

[0143] Repeat equations (34) and (35) step by step until the relative deviation of the flow rate of the two adjacent stages A or B components in the water phase is less than the set value (e.g. 1×10 -4 ), the calculation ends, and the number of recursive calculations step by step is the number of extractor stages required for this extraction section.

[0144] For the washing section of separation unit I, separation unit II or separation unit III, the flow rates of the two components in the organic phase outlet are known to be y A,1 and y B,1 From the material balance and extraction balance of the outlet stage (i.e. the first stage at the right end of the washing section, recorded as the n+m stage), we can know that:

[0145]

[0146] Solving the above equations, we can get a set of x A,1 and x B,1 The solution is then used to calculate the two-component organic phase flow rates out of the second stage (denoted as the n+m-1 stage) on the right side of the washing section using the following material transfer balance:

[0147]

[0148] Among them, f Ais the flow rate of component A in the feed liquid of the separation section.

[0149] Repeat equations (36) and (37) step by step until the relative deviation of the flow rate of the two adjacent levels of A or B components in the water phase is less than the set value (e.g. 1×10 -4 ), the calculation ends, and the number of recursive calculations step by step is the number of extractor stages required for this section.

[0150] When the first stage at the right end of the separation unit I is the kth stage, the split flow of the two components in the aqueous phase introduced from this stage is calculated as follows:

[0151] x A,k =(f a )′1·(p A )1 (38)

[0152] x B,k =(f a )′1·(p B )1 (39)

[0153] The split flow of the two components in the organic phase flowing out of the kth stage is calculated according to the following two formulas:

[0154] y A,k =(f a )′1·(p A )1+(f a )2·(p A )2 (40)

[0155] y B,k =(f a )′1·(p B )1 (41)

[0156] When the first stage at the right end of the separation unit I is the jth stage, the split flow of the two components in the aqueous phase introduced from the jth stage is calculated as follows:

[0157] x A,j =(f a )1·(p A )1 (42)

[0158] x B,j =(f a )1·(p B )1 (43)

[0159] The split flow of the two components in the organic phase flowing out of the jth stage is calculated according to the following two formulas:

[0160] y A,j =(f a )1·(p A )1+(f a )′2·(pA )2 (44)

[0161] y B,t =(f a )1·(p B )1 (45).

[0162] The beneficial effect of the present invention is that, by utilizing the linked extraction and separation process of the present invention containing two aqueous phase feed liquids with the same components but different compositions, the separation work contained in the feed liquids themselves can be fully utilized. Through reasonable combined separation process design, the purpose of achieving a theoretical minimum extraction amount and minimum washing amount lower than that required for separating the two feed liquids separately or directly mixing them for separation can be achieved, thereby reducing the total acid and alkali consumption in the extraction and separation process, saving production costs, and reducing the amount of salt-containing wastewater generated.

[0163] The specific embodiments of the present invention are further described below through examples.

[0164] Example 1

[0165] The two aqueous phases contain two rare earth components, Ce and Pr; the two components are Ce-distributed in the first aqueous phase 1 (p Ce )1 is 40%, Pr distribution (p Pr )1 is 60%, and Ce distribution in the second aqueous phase 2 (p Ce )2 is 80%, Pr distribution (p Pr )2 is 20%; the total flow rate of the two components in the first aqueous phase 1 and the second aqueous phase 2 (f a )1 and (f a )2 are 100 and 50 mol / min respectively; the separation coefficient β between the two components is 2.0.

[0166] In this example, the numerical relationship between the flow rates of the two feeds satisfies formula (4), so the second aqueous phase 2 is entirely used as the feed liquid for the extraction section of the separation unit I, and the first aqueous phase 1 is split into the following two parts:

[0167]

[0168] (f a )″1=(f a )1-(f a )′1=50.0

[0169] The first part of the flow rate of the first aqueous phase 1 is (f a )′1, linked with the second aqueous phase 2, is introduced from the kth stage of the washing section of the separation unit I, which has the same or closest composition to the first aqueous phase 1, as a washing liquid; at the same time, an organic phase is drawn from the kth stage of the washing section of the separation unit I to the separation unit II for separation, and the flow rate of the second part (remaining part) in the first aqueous phase 1 is (f a)″1, enters another separation unit III for separate separation. The separation process designed at this time is as follows Figure 3 shown.

[0170] Figure 3 The minimum extraction amount (S min ) I+II and minimum washing volume (W min ) I+II Calculate according to the two formulas:

[0171]

[0172] Minimum extraction volume of separation unit III (S min ) III and minimum washing volume (W min ) III Calculate according to the two formulas:

[0173]

[0174] Total minimum extraction volume S min and minimum washing volume W min for:

[0175] S min =120+80.0=200.0

[0176] W min =80.0+50.0=130.0

[0177] The minimum extraction and washing amounts required to separate two liquids separately or to mix the two liquids and then separate them are:

[0178]

[0179] The minimum extraction amount ΔS can be reduced by the linkage design process of the present invention. min and minimum washing volume ΔW min They are:

[0180] ΔS min =(f a )′1[(p A )1-(p A )2]=20

[0181] ΔW min =(f a )′1[(p B )2-(p B )1]=20

[0182] Finally, the theoretical number of extractor stages required for each separation stage is calculated according to the method described in step S5 of the present invention as follows:

[0183] Separation unit I extraction section: 84;

[0184] Separation unit I washing section: 20;

[0185] Separation unit II extraction section: 43;

[0186] Separation unit II washing section: 59;

[0187] Separation unit III extraction section: 37;

[0188] Separation unit III washing section 72.

[0189] Example 2

[0190] The two aqueous phases contain two rare earth components, Ce and Pr; the two components are Ce-distributed in the first aqueous phase 1 (p Ce )1 is 40%, Pr distribution (p Pr )1 is 60%, and Ce distribution in the second aqueous phase 2 (p Ce )2 is 80%, Pr distribution (p Pr )2 is 20%; the total flow rate of the two components in the first aqueous phase 1 and the second aqueous phase 2 (f a )1 and (f a )2 are 50 and 100 mol / min respectively; the separation coefficient between the two components is β = 2.0. The designed process flow is as follows Figure 4 shown.

[0191] In this example, the numerical relationship between the flow rates of the two feed liquids satisfies formula (5), so part of the second aqueous phase 2 is used as the feed liquid for the extraction section of the separation unit I for extraction separation; that is, the second aqueous phase 2 is split into the following two parts:

[0192] (f a )′2=(f a )1·(β-1)=50.0

[0193] (f a )″2=(f a )2-(f a )′2=50.0

[0194] The first part of the flow rate of the second aqueous phase 2 is (f a )′2, as the feed liquid of the extraction section of separation unit I, the first aqueous phase 1 is introduced from the jth stage of the washing section of separation unit I, which has the same or closest composition, and is used as the washing liquid; at the same time, an organic phase is drawn from the jth stage of the washing section of separation unit I to separation unit II for separation, and the flow rate of the second part (remaining part) of the second aqueous phase 2 is (fa )″2, a separate separation unit III is used for separation. The separation process designed at this time is as follows Figure 4 shown.

[0195] Figure 4 The minimum extraction amount (S min ) I Calculate as follows:

[0196]

[0197] Minimum extraction volume of separation unit II (S min ) II and minimum washing volume (W min ) II Calculate according to the two formulas:

[0198]

[0199] Minimum extraction volume of separation unit III (S min ) III and minimum washing volume (W min ) III Calculate according to the two formulas:

[0200]

[0201] Total minimum extraction volume S min and minimum washing volume W min for:

[0202] S min =(S min ) I +(S min ) II +(S min ) III =180.0

[0203] W min =(W min ) II +(W min ) III =130.0

[0204] The minimum extraction and washing amounts required to separate two liquids separately or to mix the two liquids and then separate them are:

[0205]

[0206] The minimum extraction amount ΔS can be reduced by the linkage design process of the present invention. min and minimum washing volume ΔW min They are:

[0207] ΔS min =(f a )1[(p A )1-(p A )2]=20

[0208] ΔW min =(f a )1[(p B )2-(p B )1]=20

[0209] Finally, the theoretical number of extractor stages required for each separation stage is calculated according to the method described in step (3) of the present invention as follows:

[0210] Separation unit I extraction section: 84;

[0211] Separation unit I washing section: 20;

[0212] Separation unit II extraction section: 43;

[0213] Separation unit II washing section: 59;

[0214] Separation unit III extraction section: 84;

[0215] Separation unit III washing section: 38.

[0216] The methods described herein are not limited to the specific embodiments described. The above embodiments are merely illustrative of the present invention, and the present invention may also be implemented in other specific ways or in other specific forms without departing from the gist or essential characteristics of the present invention. Therefore, the embodiments described herein are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is to be determined by the appended claims, and any variations that are equivalent to the intent and scope of the claims are intended to be within the scope of the present invention.

Claims

1. A method for designing a linked extraction and separation process for two components of liquid feed with different compositions, characterized in that: The method comprises the following steps: S1. Determine the feed liquid of the extraction section of separation unit I: separation unit I includes the extraction section of separation unit I and the washing section of separation unit I. The first aqueous phase and the second aqueous phase for the linked extraction separation both contain components A and B, and the molar percentage of the easily extractable component in the second aqueous phase is lower than that in the first aqueous phase; All or part of the second aqueous phase is used as the feed liquid for the extraction section of separation unit I; S2, determine the first water phase flow rate (f a )1 and the second aqueous phase flow rate (f a )2 numerical proportional relationship: Calculate the first water phase flow rate (f a )1 and the second water phase flow rate (f a )2's best matching ratio; If the first aqueous phase flow rate (f a )1 and the second water phase flow rate (f a )2 actual ratio ≥ the best matching ratio, then go to step S3; if the first water phase flow rate (f a )1 and the second water phase flow rate (f a )2's actual ratio is less than the best matching ratio, then proceed to step S4; S3, the entire second aqueous phase is used as the feed liquid for the extraction section of the separation unit I for extraction and separation; and the first aqueous phase is split into two parts: (f a )1=(f a )′1+(f a )″1 (6) Wherein, the flow rate of the first part in the first aqueous phase is (f a )′1, is introduced as washing liquid from the kth stage of the washing section of the separation unit I, which is linked with the second aqueous phase; the flow rate of the second part in the first aqueous phase is (f a )″1, separation treatment is carried out using separation unit III; the organic phase flowing out of the k-stage washing section of separation unit I is drawn out and introduced into separation unit II, and further separated as the feed liquid of separation unit II; S4, using part of the second aqueous phase as the feed liquid for the extraction section of the separation unit I for extraction separation; that is, splitting the second aqueous phase into two parts: (f a )2=(f a )′2+(f a )″2 The flow rate of the first part of the second aqueous phase is (f a )′2, the extraction section of the separation unit I is introduced as the feed liquid of the separation unit I, and the first aqueous phase is introduced as the washing liquid from the jth stage of the washing section of the separation unit I; the flow rate of the second part of the second aqueous phase is (f a )'2', separation treatment is carried out using separation unit III; the organic phase flowing out of the j-stage washing section of separation unit I is drawn out and introduced into separation unit II to continue separation as the feed liquid of separation unit II; S5. Use the static recursive method to calculate the number of extractor stages required for each separation stage.

2. The method for designing a linked extraction and separation process for two-component liquids of different compositions according to claim 1, characterized in that: Among them, A is the easier to extract component, and B is the harder to extract component; the molar percentages of components A and B in the first aqueous phase are (p A )1 and (p B )1, the molar percentages of components A and B in the second aqueous phase are (p A )2 and (p B )2, and (p A )1>(p A )2, (p B )1<(p B )2; The fractional flow rates of components A and B in the first aqueous phase are (f A )1=(f a )1(p A )1, (f B )1=(f a )1(p B )1; the fractional flow rates of components A and B in the second aqueous phase are (f A )2=(f a )2(p A )2,(f B )2=(f a )2(p B )2.

3. The design method of a linkage extraction separation process for two-component liquids of different compositions according to claim 2, characterized in that: Calculate the first water phase flow rate (f a )1 and the second aqueous phase flow rate (f a )2's best matching ratio: Among them, β is the separation coefficient between components A and B.

4. The method for designing a linked extraction and separation process for two-component liquids of different compositions according to claim 3, characterized in that: In step S3, (f a )′1 satisfies the following formula:

5. The method for designing a linked extraction and separation process for two-component liquids of different compositions according to claim 4, characterized in that: In step S3, the method for determining the kth stage of the washing section of separation unit I is as follows: when the molar percentages of components A and B in the aqueous phase of the kth stage of the washing section of separation unit I are exactly the same as or most similar to those of the first aqueous phase to be separated, the first portion of the first aqueous phase is introduced from the kth stage of the washing section of separation unit I as the washing liquid.

6. The method for designing a linked extraction and separation process for two-component liquids of different compositions according to claim 5, characterized in that: In step S3, the minimum extraction amount (S min ) I and minimum washing volume (W min ) I Calculate as follows: In step S3, the organic phase flow rate y drawn from the washing section k of the separation unit I is k for: and k =(S min ) I (10) The flow rate x of the first part of the first aqueous phase introduced from the kth stage of the washing section of the separation unit I k for: x k =(W min ) I =(f a )′1 (11)。 7. The method for designing a linked extraction and separation process for two-component liquids of different compositions according to claim 5, characterized in that: In step S3, the minimum extraction amount (S min ) II and minimum washing volume (W min ) II Calculate as follows:

8. The method for designing a linked extraction and separation process for two-component liquids of different compositions according to claim 6, characterized in that: In step S3, the minimum extraction amount (S min ) III and minimum washing volume (W min ) III Calculate as follows:

9. The method for designing a linked extraction and separation process for two-component liquids of different compositions according to claim 3, characterized in that: In step S4, (f a )′2 satisfies the following formula: Where β is the separation coefficient between components A and B; The method for determining the jth stage of the washing section of separation unit I is as follows: when the molar percentages of components A and B in the aqueous phase of the jth stage of the washing section of separation unit I are exactly the same as or most similar to those of the first aqueous phase to be separated, the entire first aqueous phase is introduced from the jth stage of the washing section of separation unit I as the washing liquid.

10. The method for designing a linked extraction separation process for two-component liquids of different compositions according to claim 9, characterized in that: In step S4, the minimum extraction amount (S min ) I and minimum washing volume (W min ) I Calculate as follows: In step S4, the organic phase flow rate y drawn from the jth stage of the washing section of the separation unit I is j for: and j =(S min ) I (24) The flow rate of the first aqueous phase introduced from the jth stage of the washing section of the separation unit I is x j for: x j =(f a )1 (25)。 11. The method for designing a linked extraction separation process for two-component liquids of different compositions according to claim 9, characterized in that: In step S4, the minimum extraction amount (S min ) II and minimum washing volume (W min ) II Calculate as follows:

12. The method for designing a linked extraction separation process for two-component liquids of different compositions according to claim 10, characterized in that: In step S4, the minimum extraction amount (S min ) III and minimum washing volume (W min ) III Calculate as follows:

13. The method for designing a linked extraction separation process for two-component liquids of different compositions according to any one of claims 1 to 12, characterized in that: In step S5, the number of extractor stages required for each separation unit is recursively calculated starting from the left and right ends of each separation unit according to the extraction balance and material balance relationship of the materials in each extraction and separation unit; In the extraction section of each separation unit, the aqueous phase outlet at the left end is component B, and the organic phase inlet is calculated as a blank extractant; in the washing section of each separation unit, when the organic phase outlet at the right end contains only component A, the aqueous phase inlet is calculated as a blank washing liquid; when the organic phase outlet at the right end contains both components A and B, the aqueous phase inlet introduces the first aqueous phase feed liquid.

14. The method for designing a linked extraction separation process for two-component liquids of different compositions according to claim 13, characterized in that: In step S5, the flow rate of component A as an impurity in the left outlet of separation unit I, separation unit II or separation unit III is set to x A,1 =ε A ·x B,1 ; Set the flow rate of component B as an impurity in the right outlet of separation unit II or separation unit III to y B,n+m =ε B ·y A,n+m ; Among them, ε A , ε B Determined according to the rare earth purity of products A and B, ε A =1-B product rare earth purity, ε B =1-A product rare earth purity; When the first stage at the right end of the separation unit I is the kth stage, the split flow of the two components in the aqueous phase introduced from this stage is calculated as follows: x A,k =(f a )′1·(p A )1 (38) x B,k =(f a )′1·(p B )1 (39) The split flow of the two components in the organic phase flowing out of the kth stage is calculated according to the following two formulas: y A,k =(f a )′1·(p A )1+(f a )2·(p A )2 (40) y B,k =(f a )′1·(p B )1 (41) When the first stage at the right end of the separation unit I is the jth stage, the split flow of the two components in the aqueous phase introduced from the jth stage is calculated as follows: x A,j =(f a )1·(p A )1 (42)x B,j =(f a )1·(p B )1 (43) The split flow of the two components in the organic phase flowing out of this stage is calculated according to the following two formulas: y A,j =(f a )1·(p A )1+(f a )′2·(p A )2 (44)y B,j =(f a )1·(p B )1 (45)。

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