Method for centrifugally separating and degreasing raffinate acid

Abstract

The invention relates to the technical field of extraction separation, in particular to a method for centrifugally separating and degreasing raffinate acid. The invention discloses a method for centrifugally separating and degreasing raffinate acid, which comprises the following step of: introducing a mixed solution containing the raffinate acid and an extracting agent into a centrifugal separator for separating. According to the method provided by the invention, the raffinate acid obtained through centrifugal separation is placed for more than 96 hours, the surface of the raffinate acid does not have an oil film when observed by naked eyes, and the surface of the unseparated raffinate acid has an obvious oil film phenomenon, so that the separation effect is ensured through centrifugal separation of the mixed solution, the production cost is reduced, the product quality is improved, and the environmental pollution is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of extraction and separation, and in particular to a method for centrifugal separation and deesterification of raffinate. Background Art

[0002] With the development of the chemical industry, phosphoric acid and its derivatives, as important chemical raw materials, are widely used in agriculture, food, medicine and other fields. However, in the production process of phosphoric acid, especially in the purification section of the phosphoric acid device, raffinate acid containing trace amounts of extractants is often produced. These trace amounts of extractants not only affect the purity of the phosphate product, but also have an adverse effect on the subsequent nitrophosphate fertilizer device, leading to problems in the concentration process, and thus affecting the quality of the final product. In addition, the trace amounts of extractants carried in the process condensate also bring processing difficulties to the water treatment workshop and increase the cost of sewage treatment.

[0003] At present, the common practice in the industry to remove trace amounts of extractants in raffinate acid is to let it stand naturally in the mixed acid tank of the phosphate unit and achieve partial separation by gravity. However, this method is inefficient, the separation effect is unstable, and it is difficult to completely remove trace amounts of extractants, resulting in difficulty in ensuring product quality. Therefore, it is particularly important to develop an efficient, stable and economical method for centrifugal separation and deesterification of raffinate acid. Summary of the invention

[0004] The present application provides a method for centrifugal separation and deesterification of raffinate, which reduces production costs, improves product quality and reduces environmental pollution while ensuring separation effect through centrifugal separation.

[0005] The technical solution adopted by this application to solve its technical problem is:

[0006] A method for centrifugal separation and deesterification of raffinate acid comprises introducing a mixed solution containing raffinate acid and an extractant into a centrifugal separator for separation.

[0007] In one or more technical solutions, the volume content ratio of the extractant to the raffinate acid in the mixed solution is 99:1-80:20.

[0008] In one or more technical solutions, the volume content ratio of the extractant to the raffinate acid in the mixed solution is 95:5-90:10.

[0009] In one or more technical solutions, the volume content ratio of the extractant to the raffinate in the mixed solution is 96:4-98:2.

[0010] In one or more technical solutions, when separation is performed in the centrifugal separator, the frequency control of stirring is variable frequency control, and the frequency range of the variable frequency control is within 26-46 Hz.

[0011] In one or more technical solutions, the rated power of the centrifugal separator is 0.37 kW, the rated voltage is 220 V / 380 V, the rated current is 1.63 / 0.84 A, the rated frequency is 50 Hz, and the rated speed is 2800-6500 r / min.

[0012] In one or more technical solutions, the mixed liquid is transported by a pump and introduced into a centrifugal separator for continuous centrifugal separation.

[0013] In one or more technical solutions, the pumping flow rate of the mixed liquid transported by the pump is 15-1000kg / h.

[0014] In one or more technical solutions, after the mixed solution is introduced into a centrifugal separator for separation, a target raffinate acid and a target extractant are obtained; the specific gravity of the target raffinate acid is 1.15-1.50 g / mL, and the specific gravity of the target extractant is 0.95-0.985 g / mL.

[0015] In one or more technical solutions, the weight content of the extractant in the target raffinate acid is less than 0.01%, and the weight content of the raffinate acid in the target extractant is less than 0.01%.

[0016] The beneficial effects of this application are:

[0017] The method described in this application achieves the best separation effect by controlling the frequency of stirring frequency conversion during centrifugal separation within the range of 26-46 Hz, and no entrainment is observed by naked eyes. This shows that centrifugal separation technology can achieve efficient separation in a relatively short time, significantly improving separation efficiency.

[0018] After the raffinate acid treated by centrifugal separation technology was placed for more than 96 hours, there was no oil film on the surface when observed with the naked eye, while the unseparated raffinate acid had obvious oil film on the surface. This shows that centrifugal separation technology can effectively remove trace extractants, improve the purity and quality of phosphate products, and enhance the market competitiveness of products.

[0019] Centrifugal separation technology not only improves separation efficiency, but also reduces the burden on the water treatment system. Test data shows that the extractant after separation can be effectively recycled, reducing pollution to the environment and reducing the environmental protection costs of enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0021] Figure 1 A schematic diagram of the centrifugal separation process of the method for centrifugal separation and deesterification of raffinate described in the present application;

[0022] Figure 2A schematic diagram of the operation of continuous centrifugal separation in a method for centrifugal separation and deesterification of raffinate described in the present application. DETAILED DESCRIPTION

[0023] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0024] In this application, the term "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0025] In the present application, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple, respectively.

[0026] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0027] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0028] The weight of the relevant components mentioned in the embodiment description of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the embodiment description of the present application, it is within the scope disclosed in the embodiment description of the present application. Specifically, the mass described in the embodiment description of the present application can be a mass unit known in the chemical industry such as μg, mg, g, kg, etc.

[0029] The terms "first" and "second" are used only for descriptive purposes to distinguish objects such as substances from each other, and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX may also be referred to as the second XX, and similarly, the second XX may also be referred to as the first XX. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0030] The current traditional natural standing method is simple, but has a slow separation speed and poor separation effect, and cannot meet the requirements of modern industry for efficient separation. Moreover, the presence of trace extractants in the mixed solution directly affects the purity of the phosphate product, thereby affecting the market competitiveness of the product; in addition, after the trace extractants enter the water treatment workshop, they are difficult to effectively handle, which can easily cause environmental pollution and increase the environmental pressure and cost of the enterprise. In order to solve the above technical problems, the present application provides the following Figure 1-2 The method for centrifugal separation and deesterification of raffinate acid shown includes introducing a mixed solution containing raffinate acid and an extractant into a centrifugal separator for single centrifugal separation or continuous centrifugal separation.

[0031] Specifically, the mixed solution is prepared as follows: the extractant is subjected to extraction treatment (stationary separation) on the feed liquid containing phosphoric acid, and the upper layer obtained is the extraction feed liquid; the extraction feed liquid is subjected to stripping treatment (stationary separation), and the lower layer obtained is the stripping liquid, and the stripping liquid is collected to obtain the mixed solution;

[0032] After the stripping treatment, part of the extractant in the extract liquid is not separated cleanly, causing it to be entrained into the stripping liquid. In large-scale chemical production, the mixed liquid obtained after multiple or multiple collections contains a certain amount of extractant.

[0033] The mixed liquid is introduced into a centrifugal separator for single centrifugal separation or continuous centrifugal separation. The centrifugal separator uses the centrifugal force generated by high-speed rotation to make liquids of different densities produce different motion trajectories under the action of centrifugal force, thereby achieving separation. In the present application, the difference in specific gravity (density) between the raffinate and the extractant in the mixed liquid becomes the basis of centrifugal separation; combined with controlling the rotation speed and stirring frequency of the centrifugal separator, efficient separation can be achieved in a shorter time.

[0034] In one or more embodiments, the volume ratio of the extractant to the raffinate in the mixed solution is 99.9:0.1-80:20. For example, the volume ratio of the extractant to the raffinate in the mixed solution is any value of 99.9:0.1, 99.8:0.2, 99.7:0.3, 99.6:0.4, 99.5:0.5, 99.4:0.6, 99.3:0.7, 99.2:0.8, 99.1:0.9, 99:1, 98:2, 97:3, 96:4, 95:5, 94:6, 93:7, 92:8, 91:9, 90:10, 89:11, 88:12, 87:13, 86:14, 85:15, 84:16, 83:17, 82:18, 81:19, and 80:20.

[0035] Preferably, the volume content ratio of the extractant to the raffinate in the mixed solution is 99:1-90:10, and specifically can be any value among 99:1, 98:2, 97:3, 96:4, 95:5, 94:6, 93:7, 92:8, 91:9, and 90:10.

[0036] More preferably, the volume content ratio of the extractant to the raffinate in the mixed solution is 98:2-95:5, and specifically can be any value among 98:2, 97:3, 96:4, and 95:5.

[0037] In one or more embodiments, during centrifugal separation in the centrifugal separator, the frequency of stirring is controlled at 26-46 Hz, and / or the frequency of stirring is not fixed.

[0038] Specifically, the stirring frequency is adjusted within 26-46 Hz. Variable frequency stirring can control the centrifugal force by adjusting the stirring frequency, thereby optimizing the separation effect.

[0039] In one or more embodiments, the centrifugal separator has a rated power of 0.37 kW, a rated voltage of 220 V / 380 V, a rated current of 1.63 / 0.84 A, a rated frequency of 50 Hz, and a rated speed of 2800-6500 r / min.

[0040] Specifically, the rated speed of 2800-6500r / min can generate sufficient centrifugal force to ensure the effective separation of the extractant and the raffinate acid with different specific gravities. If the actual speed is lower than 2800-6500r / min, the centrifugal force is insufficient, the separation effect is poor, and the separation may not be complete. If the actual speed exceeds 2800-6500r / min, the centrifugal force may increase, causing excessive wear of the equipment, increased energy consumption, and even damage to the equipment.

[0041] In one or more embodiments, the mixed liquid is introduced into a centrifugal separator by a pump for continuous centrifugal separation. The pumping flow rate of the mixed liquid is 15-1000 kg / h.

[0042] Specifically, by pumping the mixed liquid, a continuous production process can be achieved, avoiding the problems of low efficiency and discontinuous production caused by intermittent operation.

[0043] Specifically, the flow rate range of 15-1000 kg / h ensures that the mixed liquid enters the centrifugal separator at an appropriate rate, so that the centrifugal separator operates in a better working state, thereby achieving an efficient separation effect.

[0044] Too high a flow rate may cause the mixed liquid to enter the centrifuge too quickly, and the centrifuge cannot complete effective separation in a short time, resulting in a decrease in separation effect, and the raffinate may still carry a large amount of extractant. Too low a flow rate may cause the mixed liquid to enter the centrifuge too slowly, prolonging the separation process and affecting production efficiency.

[0045] In one or more embodiments, after the mixed solution is introduced into a centrifugal separator for separation, a target raffinate acid and a target extractant are obtained; the specific gravity of the target raffinate acid is 1.15-1.50 g / mL, and the specific gravity of the target extractant is 0.95-0.985 g / mL.

[0046] Specifically, the specific gravity of the target raffinate acid and the target extractant is designed to be within a specific range, and their density difference is utilized to ensure effective separation during the centrifugal separation process. The target raffinate acid has a high specific gravity (1.15-1.50 g / mL), while the target extractant has a low specific gravity (0.95-0.985 g / mL), which enables the two substances to be quickly separated under the action of centrifugal force, achieving efficient separation.

[0047] In one or more embodiments, the weight content of the extractant in the target raffinate acid is less than 0.01%, and the weight content of the raffinate acid in the target extractant is less than 0.01%.

[0048] Specifically, the target raffinate acid is a phosphoric acid solution, and the target extractant is an organic extractant, which can specifically extract phosphoric acid from the feed liquid containing phosphoric acid to form an extraction feed liquid.

[0049] More specifically, the organic extractant is a mixture of tributyl phosphate and an additive in a weight ratio of 6:4; the additive is preferably kerosene.

[0050] The weight content of the extractant in the target raffinate acid and the raffinate acid in the target extractant can be detected by gas chromatography or high performance liquid chromatography. The weight content of the extractant in the target raffinate acid is less than 0.01%, that is, when the target raffinate acid is subjected to gas chromatography or high performance liquid chromatography, the total weight content of tributyl phosphate and kerosene is less than 0.01%; the weight content of the raffinate acid (phosphoric acid) in the target extractant is less than 0.01%.

[0051] Example 1

[0052] A method for centrifugal separation and deesterification of raffinate acid comprises introducing a mixed solution containing raffinate acid and an extractant into a centrifugal separator for centrifugal separation, and obtaining a target extractant and a target raffinate acid after separation.

[0053] The volume ratio of the extractant to the raffinate in the mixed solution is 99:1, the density of the raffinate in the mixed solution is in the range of 1.45-1.50 g / mL, and the density of the extractant is in the range of 0.98-0.985 g / mL. The rated speed of the centrifuge is 2800 r / min, and the stirring frequency is variable-frequency regulated within 26-46 Hz during centrifugal separation.

[0054] Example 2

[0055] A method for centrifugal separation and deesterification of raffinate acid comprises introducing a mixed solution containing raffinate acid and an extractant into a centrifugal separator for centrifugal separation, and obtaining a target extractant and a target raffinate acid after separation.

[0056] The volume ratio of the extractant to the raffinate in the mixed solution is 80:20, the density of the raffinate in the mixed solution is in the range of 1.15-1.18 g / mL, and the density of the extractant is in the range of 0.95-0.96 g / mL. The rated speed of the centrifuge is 6500 r / min, and during centrifugal separation, the stirring frequency is variable-frequency regulated within 26-46 Hz.

[0057] Example 3

[0058] A method for centrifugal separation and deesterification of raffinate acid comprises introducing a mixed solution containing raffinate acid and an extractant into a centrifugal separator for centrifugal separation, and obtaining a target extractant and a target raffinate acid after separation.

[0059] The volume ratio of the extractant to the raffinate in the mixed solution is 90:10, the density of the raffinate in the mixed solution is in the range of 1.25-1.30 g / mL, and the density of the extractant is in the range of 0.97-0.98 g / mL. The rated speed of the centrifuge is 4500 / min, and during centrifugal separation, the stirring frequency is variable-frequency regulated within 26-46 Hz.

[0060] Example 4

[0061] A method for centrifugal separation and deesterification of raffinate acid comprises the steps of introducing a mixed solution containing raffinate acid and an extractant into a centrifugal separator through a pump, performing continuous centrifugal separation, and obtaining a target extractant and a target raffinate acid after separation.

[0062] The volume ratio of the extractant to the raffinate in the mixed solution is 95:5, the density of the raffinate in the mixed solution is in the range of 1.45-1.50 g / mL, and the density of the extractant is in the range of 0.98-0.985 g / mL;

[0063] The rated speed of the centrifugal separator is 2800r / min. During centrifugal separation, the stirring frequency is adjusted within 26-46Hz.

[0064] The pumping flow rate of the mixed liquid is 15kg / h.

[0065] Example 5

[0066] A method for centrifugal separation and deesterification of raffinate acid comprises the steps of introducing a mixed solution containing raffinate acid and an extractant into a centrifugal separator through a pump, performing continuous centrifugal separation, and obtaining a target extractant and a target raffinate acid after separation.

[0067] The volume ratio of the extractant to the raffinate in the mixed solution is 96:4, the density of the raffinate in the mixed solution is in the range of 1.15-1.20 g / mL, and the density of the extractant is in the range of 0.95-0.965 g / mL;

[0068] The rated speed of the centrifugal separator is 6500r / min. During centrifugal separation, the stirring frequency is adjusted within 26-46Hz;

[0069] The pumping flow rate of the mixed liquid is 1000kg / h.

[0070] Example 6

[0071] A method for centrifugal separation and deesterification of raffinate acid comprises the steps of introducing a mixed solution containing raffinate acid and an extractant into a centrifugal separator through a pump, performing continuous centrifugal separation, and obtaining a target extractant and a target raffinate acid after separation.

[0072] The volume ratio of the extractant to the raffinate in the mixed solution is 98:2, the density of the raffinate in the mixed solution is in the range of 1.35-1.40 g / mL, and the density of the extractant is in the range of 0.96-0.97 g / mL;

[0073] The rated speed of the centrifugal separator is 4400r / min. During centrifugal separation, the stirring frequency is adjusted within 26-46Hz;

[0074] The pumping flow rate of the mixed liquid is 200kg / h.

[0075] Comparative Example 1

[0076] A method for centrifugal separation and deesterification of raffinate acid comprises introducing a mixed solution containing raffinate acid and an extractant into a centrifugal separator for centrifugal separation, and obtaining a target extractant and a target raffinate acid after separation.

[0077] The volume ratio of the extractant to the raffinate in the mixed solution is 99:1, the density of the raffinate in the mixed solution is in the range of 1.45-1.50 g / mL, and the density of the extractant is in the range of 0.98-0.985 g / mL. The rated speed of the centrifuge is 1000 r / min, and the stirring frequency is variable-frequency regulated within 26-46 Hz during centrifugal separation.

[0078] Comparative Example 2

[0079] A method for centrifugal separation and deesterification of raffinate acid comprises introducing a mixed solution containing raffinate acid and an extractant into a centrifugal separator for centrifugal separation, and obtaining a target extractant and a target raffinate acid after separation.

[0080] The volume ratio of the extractant to the raffinate in the mixed solution is 99:1, the density of the raffinate in the mixed solution is in the range of 1.05-1.09 g / mL, and the density of the extractant is in the range of 0.98-0.985 g / mL. The rated speed of the centrifuge is 10000 r / min, and the stirring frequency is variable-frequency regulated within 26-46 Hz during centrifugal separation.

[0081] Comparative Example 3

[0082] A method for centrifugal separation and deesterification of raffinate acid comprises the steps of introducing a mixed solution containing raffinate acid and an extractant into a centrifugal separator through a pump, performing continuous centrifugal separation, and obtaining a target extractant and a target raffinate acid after separation.

[0083] The volume ratio of the extractant to the raffinate in the mixed solution is 95:5, the density of the raffinate in the mixed solution is in the range of 1.25-1.30 g / mL, and the density of the extractant is in the range of 0.98-0.985 g / mL;

[0084] The rated speed of the centrifugal separator is 2800r / min. During centrifugal separation, the stirring frequency is adjusted within 26-46Hz;

[0085] The pumping flow rate of the mixed liquid is 5kg / h.

[0086] Specifically, the density of the raffinate and the density of the extractant in the mixed solution in Examples 1-6 and Comparative Example 1 are calculated by detecting the density of the upper layer of the mixed solution and the lower layer of the mixed solution.

[0087] The target raffinate acid and target extractant prepared in Examples 1-5 and Comparative Examples 1-3 were tested for content and density and observed after standing at room temperature for 120 hours. The test results are summarized in Table 1 below.

[0088] Table 1

[0089]

[0090]

[0091] From Table 1, it can be seen that in all embodiments, the weight content of the extractant in the target raffinate acid is less than 0.01%, and the weight content of the raffinate acid in the target extractant is also less than 0.01%. Therefore, the raffinate acid and the extractant can be separated very effectively by centrifugal separation technology; the separated raffinate acid and the extractant both show good stability, without stratification or oil film phenomenon, and remain stable after standing for a long time.

[0092] Examples 4-6 use a pumping method to achieve continuous production, and can maintain a stable separation effect even under different flow conditions (such as 15kg / h to 1000kg / h), which is an important advantage for industrial applications. The method described in this application significantly improves production efficiency.

[0093] In Comparative Example 1, the rated speed of the centrifuge is only 1000 r / min, which is much lower than 2800-6500 r / min in the embodiment. Because the lower speed means that the centrifugal force generated is insufficient to effectively separate liquids of different densities, resulting in more residual extractant in the raffinate acid, the weight content of the extractant in the target raffinate acid is 0.5%, and the weight content of the raffinate acid in the target extractant is 0.35%.

[0094] In Comparative Example 2, the rotation speed of the centrifuge is very high (10000r / min), but the density of the raffinate in the mixed solution is close to that of the extractant (1.05-1.09g / mL vs 0.98-0.985g / mL), which makes it difficult for the two to be completely separated at high speed. In addition, too high a rotation speed may also cause excessive wear of the equipment and affect the separation efficiency. Therefore, the weight content of the extractant in the target raffinate is 0.8%, and the weight content of the raffinate in the target extractant is as high as 5.3%.

[0095] In Comparative Example 3, the pumping flow rate of the mixed liquid is only 5 kg / h, which is much lower than 15-1000 kg / h in the embodiment. The low flow rate may cause the mixed liquid to enter the centrifugal separator too slowly, thereby prolonging the separation time and reducing the separation efficiency; at the same time, the slow feed rate may also cause the material to stay in the separator for too long, increasing the possibility of remixing of the two phases. Therefore, the weight content of the extractant in the target raffinate acid is 0.4%, and the weight content of the raffinate acid in the target extractant is 0.7%.

[0096] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for centrifugal separation and deesterification of raffinate, characterized in that: The method comprises introducing a mixed liquid containing raffinate acid and an extractant into a centrifugal separator for separation.

2. The method according to claim 1, characterized in that The volume content ratio of the extractant to the raffinate in the mixed solution is 99:1-80:

20.

3. The method according to claim 1, characterized in that The volume content ratio of the extractant to the raffinate in the mixed solution is 95:5-90:

10.

4. The method according to claim 1, characterized in that: The volume content ratio of the extractant to the raffinate in the mixed solution is 96:4-98:

2.

5. The method according to claim 1, characterized in that When separation is carried out in the centrifugal separator, the frequency of stirring is controlled by variable frequency.

6. The method according to claim 1, characterized in that The rotation speed of the centrifugal separator is 2800-6500r / min.

7. The method according to claim 1, characterized in that The mixed liquid is transported by a pump and introduced into a centrifugal separator for continuous centrifugal separation.

8. The method according to claim 7, characterized in that The pumping flow rate of the mixed liquid conveyed by the pump is 15-1000kg / h.

9. The method according to claim 1, characterized in that: After the mixed solution is introduced into a centrifugal separator for separation, target raffinate acid and target extractant are obtained; the specific gravity of the target raffinate acid is 1.15-1.50 g / mL, and the specific gravity of the target extractant is 0.95-0.985 g / mL.

10. The method according to claim 9, characterized in that The weight content of the extractant in the target raffinate acid is less than 0.01%, and the weight content of the raffinate acid in the target extractant is less than 0.01%.

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