Saturated waste salt solution salt separation method based on density detection

Abstract

The invention relates to a saturated waste salt solution salt separation method based on density detection. The method comprises the following steps: (1) preparing a saturated salt solution; (2) filtering carbon residues therein; (3) continuously stirring the solution, ensuring a homogeneous environment of the solution, and keeping the temperature of the solution at 25-27 DEG C; (4) a high-precision densimeter is used, the effective number of bits reaches five, and the solution contact material is titanium; (5) drawing a'density-solution component 'relation network curve; (6) obtaining sodium chloride purity node data and corresponding density node data of the salt separation process; and (7) when the density of the saturated pyrolysis waste salt solution is smaller than the density node data, the solution enters an evaporative crystallization process, and when the density of the saturated pyrolysis waste salt solution is larger than the density node data, the solution enters a freezing crystallization process. The method has the advantages of accurate detection, simple operation, low cost and the like.

Description

Technical Field

[0001] The invention relates to a method for detecting and separating chemical waste salt, in particular to a method for separating saturated waste salt solution based on density detection, and belongs to the technical field of post-treatment of industrial waste salt. Background Art

[0002] In chemical production and many other fields, accurate and efficient detection of components in waste salt solutions is of vital importance, which is directly related to the effectiveness of subsequent salt separation processes and the efficient recycling of resources. The components of saturated waste salt solutions are complex, mainly sodium salts, potassium salts, and ammonium salts. Among them, waste salts mainly composed of sodium salts account for more than 76%, and the main components are sodium chloride and sodium sulfate. How to efficiently detect the components in waste salt solutions is an important issue faced in its resource utilization process.

[0003] At present, the methods for detecting the components of saturated waste salt solution mainly include ion chromatography detection method, chemical analysis method, etc. Although ion chromatography detection method can detect specific ions, the detection process requires high-precision instruments, which is costly and susceptible to interference. Chemical analysis method has high accuracy, but the analysis process is cumbersome and time-consuming.

[0004] The most common industrial method for detecting the components of sodium salt in saturated waste salt solution is ion chromatography, which can effectively detect to a certain extent, but has low timeliness and takes a long time for experiments and detection. When the salt ion concentration is high, it is easy to damage the instruments and equipment, affecting the accuracy of the test results. Therefore, how to detect the components in waste salt solution with high accuracy and timeliness has always been a pain point and difficulty in the field of detection. In industrial production, due to the low efficiency of detecting components in waste salt solution, the equipment capacity utilization rate cannot be effectively improved, and the production and disposal costs are also difficult to reduce.

[0005] Therefore, how to use a more efficient and accurate method to detect the components in the waste salt solution with sodium chloride and sodium sulfate as the main components is an urgent problem to be solved in the field of waste salt treatment. The present invention is thus generated. Summary of the invention

[0006] In view of the above technical problems of the prior art, the purpose of the present invention is to provide a method for separating saturated waste salt solutions based on density detection, which establishes a "density-solution component" relationship network and uses a high-precision density meter to accurately detect the solution components. There is no need to rely on expensive detection equipment, which avoids the influence of complex operating processes and interference factors. At the same time, it can better adapt to different types of waste salt solutions, improve the versatility and applicability of detection, and provide strong technical support for the efficient treatment and resource recovery of waste salt.

[0007] To achieve the above object, the present invention is implemented by the following technical solutions:

[0008] A method for separating saturated waste salt solution based on density detection comprises the following steps:

[0009] (1) preparing a saturated salt solution, wherein the solution components are sodium chloride and sodium sulfate, the purity gradient range of the sodium chloride solution in the saturated salt solution is 9-98%, and the salt used to prepare the saturated salt solution is from the same batch;

[0010] (2) filtering the solution through a filter cloth to filter out the carbon residue therein;

[0011] (3) The solution is continuously stirred to ensure a homogeneous environment and the solution temperature is maintained at 25-27°C;

[0012] (4) Use a high-precision density meter with five effective digits and the solution contact material is titanium;

[0013] (5) Use a high-precision density meter to test saturated salt solutions with different purity gradients and draw a "density-solution component" relationship network curve;

[0014] (6) According to the sodium chloride purity selection node of the evaporation crystallization and cooling crystallization process branches in the crystallization salt separation process, corresponding to the density data under the purity, the density data under the purity node is defined as the node of the density intelligent control salt separation process, and the sodium chloride purity node and the corresponding density node data of the salt separation process are obtained;

[0015] (7) When the density of the saturated pyrolysis waste salt solution is less than the density node data in step (6), the solution enters the evaporation crystallization process; when the density of the saturated pyrolysis waste salt solution is greater than the density node data in step (6), the solution enters the freezing crystallization process;

[0016] (8) The saturated waste salt solutions prepared from different batches of pyrolysis waste salt are used to detect the purity of sodium chloride in the salt separation process, and the density data under the sodium chloride purity node in step (6) is determined as the density node of the density intelligent control salt separation process system.

[0017] The waste salt used in the saturated waste salt solution in step (1) is pyrolysis waste salt, the main component of which is sodium chloride with a purity of 95-99%. The required purity gradient requires high-purity sodium sulfate to be obtained from sodium chloride waste salt through a replacement process, with a sodium sulfate purity of 95-98%, a TOC content of 76 mg / kg, a whiteness of 87-92, a water-insoluble matter of 0.03-0.08, a total hardness of 0-0.01, and a water content of 0.97-3.85%.

[0018] The waste salt used in the saturated waste salt solution in step (1) is industrial salt, the main component of which is sodium chloride with a purity of 98.5-99.9%. The purity gradient required for the configuration is industrial salt sodium sulfate with a purity of 97.5-99.9%.

[0019] In the step (3), the temperature of the saturated pyrolysis waste salt solution is 25.4-25.6°C, and the temperature of the saturated industrial salt solution is 26.8-27.4°C.

[0020] The pore size of the filter cloth in step (2) is 50 um.

[0021] The sodium chloride purity node of the salt separation process in step (6) is 78.37%, and the corresponding density node data is 1.18829 g / cm 3 .

[0022] The saturated waste salt solution salt separation method based on density detection of the present invention has the following beneficial effects:

[0023] 1. Improved accuracy: Through the study of saturated salt solutions of different purities, it was found that the density change curve is highly correlated with the purity of the NaCl component in the solution, with a high correlation coefficient, which provides a scientific basis for accurately judging the solution components and improves the accuracy of detection.

[0024] 2. Good cost-effectiveness: It avoids the investment of expensive equipment and reduces equipment costs. At the same time, the simplified operation process reduces labor costs and time costs, and improves cost-effectiveness.

[0025] 3. Strong versatility: It is suitable for different types of waste salt solutions. Whether it is pyrolysis waste salt or saturated solution of industrial salt, this method can be effectively used for detection, and it has wide versatility.

[0026] 4. Provide strong support for resource recovery: The present invention can accurately determine the selection of salt separation process branches, provide clear guidance and effective technical support for the efficient treatment and resource recovery of waste salt, and provide a new solution for the online detection and resource utilization of waste salt solution components. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the process flow chart of the density intelligent control salt distribution system;

[0028] Figure 2 The density change curve of saturated industrial salt solution with different purities: Y = -0.00139X + 1.2919, R 2 =0.96087.

[0029]

[0030]

[0031] Figure 3 The density change curve of saturated industrial waste salt solution with different purities: Y = -0.00108X + 1.27264, R 2=0.98819

[0032] equation y=a+b*x Drawing B Weight <![CDATA[Instrument (=1 / ei - 2)]]> intercept 1.27264±0.00189 Slope -0.00108±2.71998E- Residual sum of squares 121394.91808 Pearson's -0.99439 R-squared (COD) 0.98881 Adjusted R-squared 0.98819

[0033] Figure 4 This is the process operation effect of the density intelligent salt separation system: the density in evaporation crystallization is 1.18421<1.18829; the density in cooling crystallization is 1.23731<1.18829.

[0034] Figure 5 The continuous operation effect of the density intelligent salt separation process: the density node is 1.18829g / cm 3 . DETAILED DESCRIPTION

[0035] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0036] like Figure 1-5 As shown, in the process of waste salt resource treatment of the present invention, the main components of industrial waste salt are sodium chloride and sodium sulfate. The waste salt is pyrolyzed to remove organic matter therein, and the pyrolysis waste salt produced is dissolved at a mass percentage of 33%, and filtered to obtain a saturated waste salt solution. The solution is tested for density by a high-precision density meter, and the selection of the salt separation process branch is automatically determined according to the nodes in the "density-solution component" relationship network, and enters evaporation crystallization or cooling crystallization. When the components of the solution show regular changes, the density of the solution also changes regularly.

[0037] The present invention is configured with industrial salt sodium chloride-sodium sulfate as the main component, wherein the purity range of sodium chloride is 10-95%, and a total of 20 groups of saturated industrial salt solutions are provided. The density change curves of saturated industrial salt solutions with different purities show a significant linear trend, and the fitting degree of the curve is good, and the correlation coefficient R 2 It reaches 0.96087, indicating that there is a high correlation between density and the purity of the NaCl component in the solution, which meets the needs of industrial applications.

[0038] The present invention can also be configured with a saturated solution of pyrolysis waste salt, the main components of which are sodium chloride and sodium sulfate, wherein the purity of sodium chloride ranges from 9 to 98%. The density change curves of saturated waste salt solutions of different purities show a strong linear correlation trend, a high degree of fit, and a correlation coefficient R 2 The value reached 0.98819, successfully establishing a standard model for the relationship between different purity components and density changes in actual industrial waste salt saturated solutions, providing a scientific basis and clear guidance for distinguishing different salt separation processes through density nodes in the future.

[0039] The saturated waste salt solution salt separation method based on density detection of the present invention comprises the following steps:

[0040] (1) A saturated salt solution is prepared, wherein the solution components are sodium chloride and sodium sulfate, the purity gradient range of the sodium chloride solution in the saturated salt solution is 9-98%, and the salt used to prepare the saturated salt solution is from the same batch.

[0041] Among them, the waste salt used for the saturated waste salt solution is pyrolysis waste salt, the main component of which is sodium chloride with a purity of 95-99%; the required purity gradient requires high-purity sodium sulfate to be obtained through a replacement process for sodium chloride waste salt, with a sodium sulfate purity of 95-98%, a TOC content of 76 mg / kg, a whiteness of 87-92, a water-insoluble matter of 0.03-0.08, a total hardness of 0-0.01, and a moisture content of 0.97-3.85%.

[0042] Alternatively, the waste salt used in the saturated waste salt solution is industrial salt, the main component of which is sodium chloride with a purity of 98.5-99.9%, and the purity gradient required for configuration is industrial salt sodium sulfate with a purity of 97.5-99.9%.

[0043] (2) Filter the solution through a filter cloth with a pore size of 50um to filter out the carbon residue. (3) Stir the solution continuously to ensure a homogeneous environment for the solution, and keep the solution temperature at 25-27°C; wherein the temperature of the saturated pyrolysis waste salt solution is 25.4-25.6°C, and the temperature of the saturated industrial salt solution is 26.8-27.4°C.

[0044] (4) Use a high-precision density meter with five effective digits and the solution contact material is titanium.

[0045] (5) Use a high-precision density meter to detect saturated salt solutions with different purity gradients and draw a "density-solution component" relationship network curve.

[0046] (6) According to the sodium chloride purity selection node of the evaporation crystallization and cooling crystallization process branches in the crystallization salt separation process, the density data under the purity is set as the node of the density intelligent control salt separation process. The obtained sodium chloride purity node of the salt separation process is 78.37%, and the corresponding density node data is 1.18829 g / cm 3 .

[0047] (7) When the density of saturated pyrolysis waste salt solution is less than 1.18829 g / cm 3 When the density of the saturated pyrolysis waste salt solution is greater than 1.18829 g / cm 3 When the temperature is 400 °C, the solution enters the freeze crystallization process.

[0048] (8) The density data of the saturated waste salt solutions prepared from different batches of pyrolysis waste salt were tested when the purity of sodium chloride in the salt separation process was 78.37%, and the density data was determined as the density node of the density intelligent control salt separation process system.

[0049] Example 1

[0050] In this embodiment 1, different components of industrial salt (NaCl: Na2SO4) were prepared, and the NaCl purity gradient ranged from 10-95%, with a total of 20 groups of saturated industrial salt solutions. The industrial salt was dissolved and stirred continuously, and the temperature range was 26.8-27.4°C. Figure 2 It can be seen that the density change curves of saturated industrial salt solutions of different purities show a significant linear trend. The curve has a good fit and the correlation coefficient R 2 It reaches 0.96087, indicating that there is a high correlation between density and the purity of the NaCl component in the solution, which meets the needs of industrial applications.

[0051] Example 2

[0052] In this embodiment 2, different components of pyrolysis waste salt (NaCl: Na2SO4) were prepared, and the NaCl purity gradient ranged from 9-98%, with a total of 20 groups of saturated pyrolysis waste salt solutions. The pyrolysis waste salt was dissolved and stirred continuously, and the temperature range was 25.4-25.6°C. Figure 3 It can be seen that the density change curve of saturated waste salt solution with the same purity shows a strong linear correlation trend, with a very high fitting degree and a correlation coefficient R 2 It reached 0.98819, and successfully established a standard model for the relationship between different purity components and density changes in actual industrial waste salt saturated solutions.

[0053] Example 3

[0054] In this embodiment 3, the purity node of the evaporation-freezing crystallization process is 78%, and the corresponding density node of the saturated pyrolysis waste salt solution is 1.18829 g / m 3 , and set this density node as the salt distribution node of the density intelligent control salt distribution system. Figure 4 The automatic selection of salt separation process under the control of density intelligent system and the effect of evaporation-freezing crystallization salt separation process are demonstrated. The purity of saturated pyrolysis waste salt solution is 85.3%. The solution passes through the density intelligent salt separation system, and the density data is 1.18421g / m 3 , which is less than the density of the intelligent salt distribution system node 1.18829g / m 3 The system determines that the solution enters the evaporation crystallization process. The purity of the crystallized salt produced is greater than 90%. The purity of the product salt after washing and purification is greater than 98.5%, which meets the purity standard of first-class industrial salt. The mother liquor after evaporation and crystallization enters the density intelligent control system for density data detection and process selection. The density detection data of the mother liquor is 1.23731g / m 3 , greater than the density of the intelligent salt distribution system node 1.18829g / m 3, the system determines that the solution enters the freezing crystallization process. In order to verify the reliability of the density intelligent system, the purity of the mother liquor was 75.97%, which met the conditions for entering the freezing crystallization process. The purity of the crystallized salt produced was 92.97%. After washing and purification, the purity of the product salt was 98.34%, reaching the secondary standard of industrial salt.

[0055] Figure 5 The purity of the crystallized salt produced in each step of the mixed pyrolysis waste salt solution with a purity of 85.30% is demonstrated. This continuous operation is mainly divided into five steps. The first step is to evaporate and crystallize the initial saturated solution; the second step is to freeze and crystallize the mother liquor after evaporation and crystallization; then, the frozen crystallization mother liquor is evaporated-evaporated-frozen. The results show that the first part is salted with 85.30% of the mixed components, and the solution density is 1.17846g / m 3 , less than the density node 1.18829g / m 3 At this time, the density salt control system determines to enter the evaporation crystallization process. The purity of the product salt of evaporation crystallization is about 95%, and the product meets the standard after the subsequent process of salt washing. At the same time, the purity of the mother liquor is between 73% and 77%, and the mother liquor re-enters the density intelligent control system, and its solution density is 1.20186g / m 3 , greater than the density node 1.18829g / m 3 , at this time the system determines to enter the freezing crystallization process. The purity of the crystalline salt produced by the freezing crystallization process is above 90%, and the product meets the standards after washing the salt. At this time, the purity of the frozen crystallization mother liquor is as high as 91%. Since a large amount of sodium sulfate crystalline salt is precipitated from the solution at this time, the solution is already in an unsaturated state and does not meet the saturated salt solution conditions required for the density intelligent salt separation system control. At this time, it is directly determined that the solution enters the evaporation crystallization process for evaporation crystallization, so that the solution transitions from an unsaturated state to a saturated state, and further precipitates crystalline salt crystals. The purity of the crystalline salt produced by the third step of evaporation and crystallization is 94.63%. After washing and purification, the purity of the product salt reaches 98.98%. At this time, the mother liquor is already in a saturated state, which meets the judgment conditions of the density intelligent salt separation control system. The density of the solution is 1.18597g / m 3 , less than the density node 1.18829g / m 3 The system determines that the evaporation crystallization process has been entered, and the purity of the product salt produced meets the industrial salt standard. The density of the mother liquor is 1.19873g / m 3 , greater than the density node 1.18829g / m 3 , the system determines that it has entered the freezing crystallization process, and the purity of the output salt also meets the industrial salt standard. This implementation case shows that the process can operate continuously and stably, efficiently process actual waste salt, and achieve efficient recycling and reuse of resources.

[0056] The high-precision densitometer used in the present invention may be a densitometer of model DMF-1-CRTI produced by Beijing Shouke Shihua.

[0057] The present invention does not need to rely on expensive detection equipment, avoids the influence of complicated operation process and interference factors. At the same time, it can better adapt to different types of waste salt solutions, improve the versatility and applicability of detection, and provide strong technical support for efficient treatment and resource recovery of waste salt. Compared with traditional detection methods, the present invention has the advantages of accurate detection, simple operation, low cost, etc.

[0058] The above embodiments are only used to explain the inventive concept of the present invention, rather than to limit the protection of the rights of the present invention. Any non-substantial changes to the present invention using this concept shall fall within the protection scope of the present invention.

Claims

1. A method for separating saturated waste salt solution based on density detection, characterized in that The following steps are involved: (1) preparing a saturated salt solution, wherein the solution components are sodium chloride and sodium sulfate, the purity gradient range of the sodium chloride solution in the saturated salt solution is 9-98%, and the salt used to prepare the saturated salt solution is from the same batch; (2) filtering the solution through a filter cloth to filter out the carbon residue therein; (3) The solution is continuously stirred to ensure a homogeneous environment and the solution temperature is maintained at 25-27°C; (4) Use a high-precision density meter with five effective digits and the solution contact material is titanium; (5) Use a high-precision density meter to detect saturated salt solutions with different purity gradients and draw a "density-solution component" relationship network curve; (6) According to the sodium chloride purity selection node of the evaporation crystallization and cooling crystallization process branches in the crystallization salt separation process, corresponding to the density data under the purity, the density data under the purity node is defined as the node of the density intelligent control salt separation process, and the sodium chloride purity node and the corresponding density node data of the salt separation process are obtained; (7) When the density of the saturated pyrolysis waste salt solution is less than the density node data in step (6), the solution enters the evaporation crystallization process; when the density of the saturated pyrolysis waste salt solution is greater than the density node data in step (6), the solution enters the freezing crystallization process; (8) The saturated waste salt solutions prepared from different batches of pyrolysis waste salt are used to detect the purity of sodium chloride in the salt separation process, and the density data under the sodium chloride purity node in step (6) is determined as the density node of the density intelligent control salt separation process system.

2. The method for separating saturated waste salt solution based on density detection according to claim 1, characterized in that: The waste salt used in the saturated waste salt solution in step (1) is pyrolysis waste salt, the main component of which is sodium chloride with a purity of 95-99%. The required purity gradient requires high-purity sodium sulfate to be obtained from sodium chloride waste salt through a replacement process, with a sodium sulfate purity of 95-98%, a TOC content of 76 mg / kg, a whiteness of 87-92, a water-insoluble matter of 0.03-0.08, a total hardness of 0-0.01, and a water content of 0.97-3.85%.

3. The method for separating saturated waste salt solution based on density detection according to claim 1, characterized in that: The waste salt used in the saturated waste salt solution in step (1) is industrial salt, the main component of which is sodium chloride with a purity of 98.5-99.9%. The purity gradient required for the configuration is industrial salt sodium sulfate with a purity of 97.5-99.9%.

4. The method for separating saturated waste salt solution based on density detection according to claim 1, characterized in that: In the step (3), the temperature of the saturated pyrolysis waste salt solution is 25.4-25.6°C, and the temperature of the saturated industrial salt solution is 26.8-27.4°C.

5. The method for separating saturated waste salt solution based on density detection according to claim 1, characterized in that: The pore size of the filter cloth in step (2) is 50 um.

6. The method for separating saturated waste salt solution based on density detection according to claim 1, characterized in that: The sodium chloride purity node of the salt separation process in step (6) is 78.37%, and the corresponding density node data is 1.18829 g / cm 3 .

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