Method for determining mass fraction of ammonium nitrate in ammonium nitrate solution

Abstract

The invention relates to the technical field of ammonium nitrate solutions, and provides a method for determining the mass fraction of ammonium nitrate in an ammonium nitrate solution, and the method comprises the following steps: obtaining near infrared spectrum data of a plurality of modeling samples through a near infrared spectrometer, the plurality of modeling samples being a plurality of ammonium nitrate solutions with different concentrations; transferring a set volume of component solution from the modeling sample, and obtaining the solution mass and molar concentration of the component solution; obtaining the mass fraction of ammonium nitrate in the modeling sample based on the solution mass and molar concentration of the component solution; establishing a prediction model based on the corresponding relationship between the near infrared spectrum data and the mass fractions of the plurality of modeling samples; acquiring near infrared spectrum data of a to-be-detected sample through the near infrared spectrometer; and based on the prediction model and the near infrared spectrum data of the to-be-detected sample, obtaining the mass fraction of ammonium nitrate in the to-be-detected sample. The mass fraction of ammonium nitrate in a to-be-detected sample can be obtained by detecting near infrared spectrum data of the to-be-detected sample.

Description

Technical Field

[0001] The present application relates to the technical field of ammonium nitrate solutions, and in particular to a method for determining the mass fraction of ammonium nitrate in an ammonium nitrate solution. Background Art

[0002] This section is intended to provide a background or context for the embodiments of the present application. No description herein is admitted to be prior art by virtue of its inclusion in this section.

[0003] The history of ammonium nitrate synthesis can be traced back to 1659. In the early 20th century, due to the rapid development of the synthetic ammonia industry, the production of ammonium nitrate had sufficient raw materials, and its synthesis industry flourished. It is also widely used worldwide as a representative substance of modern chemical industry synthesis.

[0004] Ammonium nitrate is an important chemical raw material, mainly used in military, industrial, agricultural and other fields. In the military and industrial fields, ammonium nitrate is an extremely important chemical reagent, which is processed in large quantities into civilian blasting equipment and military energetic materials, especially the production of industrial explosives. In addition, ammonium nitrate is also oxidizing, and it is low-cost, clean and efficient, so it is also an environmentally friendly solid propellant. In industry, ammonium nitrate is also used to make glass, vitamin B, pesticides, etc. In agriculture, due to the extremely high nitrogen content in ammonium nitrate, it is second only to urea in commonly used solid nitrogen fertilizers, so it is also an important agricultural fertilizer. In short, ammonium nitrate is a very important inorganic chemical raw material with a wide range of uses, large demand, and requires a lot of synthesis.

[0005] At present, the ammonium nitrate production processes at home and abroad are all based on the principle of acid-base neutralization reaction. More water will be produced during the synthesis process, and the concentration of the ammonium nitrate solution finally produced is often low. The mass fraction of the ammonium nitrate solution produced by the initial normal pressure neutralization process is generally 40%-60%. Even with the current pressurized neutralization process, the mass fraction of the ammonium nitrate solution produced cannot be increased to the mass fraction required for subsequent granulation. Therefore, it is necessary to measure the mass fraction of ammonium nitrate in the ammonium nitrate solution to control the process operation flow. And because the acid-base neutralization reaction releases a large amount of heat, the influence of temperature needs to be considered during measurement. In addition, in the production of explosives, ammonium nitrate is transported in the form of high-purity ammonium nitrate solution under pressurized heating conditions. There is also a demand for the measurement of mass fraction under this working condition, so a method for determining the mass fraction of ammonium nitrate in ammonium nitrate solution at high temperature is needed. Summary of the invention

[0006] In view of this, an embodiment of the present application hopes to provide a method for determining the mass fraction of ammonium nitrate in an ammonium nitrate solution. By detecting the near-infrared spectral data of the sample to be tested and based on the prediction model, the mass fraction of ammonium nitrate in the sample to be tested can be obtained, and the operation is simple and convenient.

[0007] The present application embodiment provides a method for determining the mass fraction of ammonium nitrate in an ammonium nitrate solution, comprising:

[0008] Acquiring near infrared spectral data of a plurality of modeling samples by a near infrared spectrometer, wherein the plurality of modeling samples are ammonium nitrate solutions of a plurality of different concentrations;

[0009] Pipetting a set volume of a component solution from the modeling sample, and obtaining a solution mass and a molar concentration of the component solution;

[0010] Obtaining the mass fraction of ammonium nitrate in the modeling sample based on the solution mass and molar concentration of the component solution;

[0011] Establishing a prediction model based on the correspondence between the near-infrared spectral data and the mass scores of the plurality of modeling samples;

[0012] Acquire near infrared spectrum data of the sample to be tested by the near infrared spectrometer;

[0013] Based on the prediction model and the near-infrared spectrum data of the sample to be tested, the mass fraction of ammonium nitrate in the sample to be tested is obtained.

[0014] In some embodiments, the mass fraction determination method comprises:

[0015] Disposing an ammonium nitrate solution in a first container;

[0016] A plurality of the modeling samples are configured based on the ammonium nitrate solution in the first container.

[0017] In some embodiments, the ammonium nitrate solution is prepared in the first container, comprising:

[0018] Adding ammonium nitrate solid and deionized water into the first container to prepare an initial solution, and continuously heating the initial solution to maintain the initial solution at a preset temperature;

[0019] Deionized water was added to the initial solution until the ammonium nitrate in the initial solution was completely dissolved.

[0020] In some embodiments, the mass fraction of ammonium nitrate in the initial solution is between 60% and 98%.

[0021] In some embodiments, configuring a plurality of the modeling samples based on the ammonium nitrate solution in the first container comprises:

[0022] preparing a plurality of second containers of deionized water having a preset volume;

[0023] Implementing the pipetting step specifically includes: each time transferring a set volume of the component solution from the first container to the second container, and after each removal of the set volume of the component solution, adding deionized water to the first container to form the next modeling sample;

[0024] The pipetting step is repeatedly performed to obtain a plurality of the modeling samples and a plurality of second containers having the preset volumes of deionized water and the set volumes of the component solutions.

[0025] In some embodiments, removing a set volume of a component solution from the modeling sample and obtaining the solution mass and molar concentration of the component solution comprises:

[0026] preparing a second container with a preset volume of deionized water;

[0027] obtaining a first mass of a second container of deionized water having the preset volume;

[0028] Pipetting a set volume of aliquot solution from the modeling sample into the second container;

[0029] obtaining a second mass of a second container having the preset volume of deionized water and the set volume of the component solution;

[0030] The solution mass of the component solution is obtained based on the second mass and the first mass.

[0031] In some embodiments, removing a set volume of a component solution from the modeling sample and obtaining the solution mass and molar concentration of the component solution comprises:

[0032] The molar concentration of the component solution is obtained by potentiometric titration of the component solution in the second container.

[0033] In some embodiments, the molar concentration of the component solutions is obtained by potentiometric titration.

[0034] In some embodiments, the mass of the solution of the portion is obtained by weighing.

[0035] In some embodiments, the prediction model is a partial least squares model.

[0036] The mass fraction determination method provided in the embodiment of the present application obtains the near-infrared spectral data of the modeling sample through a near-infrared spectrometer, obtains the true value of the mass fraction of ammonium nitrate in the modeling sample based on the solution mass and molar concentration of the component solution, and establishes a prediction model based on the correspondence between the near-infrared spectral data and the mass fraction. After the prediction model is established, it is only necessary to collect the near-infrared spectral data of the sample to be tested with an unknown mass fraction each time, and bring the near-infrared spectral data into the prediction model to obtain the mass fraction of ammonium nitrate in the sample to be tested, which is simple and convenient to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of a process for determining the mass fraction of ammonium nitrate in an ammonium nitrate solution in some embodiments of the present application;

[0038] Figure 2 This is a distribution diagram of the true value and relative deviation of the mass fraction of the verified samples in some embodiments of the present application. DETAILED DESCRIPTION

[0039] The following is a further detailed description of the implementation of the present application in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present application but cannot be used to limit the scope of the present application.

[0040] The various specific technical features and embodiments described in the specific implementation methods can be combined in any suitable manner without contradiction. For example, different implementation methods can be formed by combining different specific technical features / embodiments. In order to avoid unnecessary repetition, the various possible combinations of the specific technical features / embodiments in this application are no longer described separately. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. The application is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0041] It should be noted that, in the embodiments of the present application, “multiple” includes two and more than two.

[0042] In the related art, the methods for measuring ammonium nitrate in ammonium nitrate solution include the following: 1) using ultrasonic and temperature sensors to measure the concentration of ammonium nitrate. This method mainly uses ultrasonic and temperature sensors to measure the sound velocity and temperature of the ammonium nitrate aqueous solution, and obtains the concentration of the ammonium nitrate solution based on the existing database comparison. However, this method is easily affected by temperature, and its own measurement deviation is large and the accuracy is low; 2) using the different crystallization point temperatures of ammonium nitrate of different concentrations to measure the concentration of ammonium nitrate. This method is complicated to operate, and because the ammonium nitrate in the ammonium nitrate solution needs to be precipitated, it is generally an offline analysis method and cannot achieve in-situ analysis. ; 3) The conductivity method is used to measure the concentration of ammonium nitrate. This method measures the conductivity of ammonium nitrate solutions of known concentrations at different temperatures to establish a corresponding working curve, and then measures the conductivity of ammonium nitrate of unknown concentration and brings it into the working curve to calculate its concentration. However, this method also has the problems of cumbersome operation and insufficient measurement accuracy; 4) Acid-base titration method. Since ammonium nitrate is a salt of strong acid and weak base, the acid-base titration method can be used to measure the concentration of ammonium nitrate by detecting pH jumps. However, this method is generally an off-line analysis method and requires sampling at other locations for testing, and cannot achieve in-situ analysis.

[0043] See also Figure 1 The present application embodiment provides a method for determining the mass fraction of ammonium nitrate in an ammonium nitrate solution, and the mass fraction determination method includes:

[0044] S10, obtaining near-infrared spectrum data of a plurality of modeling samples by a near-infrared spectrometer, wherein the plurality of modeling samples are ammonium nitrate solutions of a plurality of different concentrations;

[0045] Different concentrations of ammonium nitrate solutions correspond to different near-infrared spectral data. In other words, each near-infrared spectral data corresponds to one concentration. The near-infrared spectral data include but are not limited to near-infrared light absorbance.

[0046] Specifically, the modeling sample can be measured by a near infrared spectrometer to obtain near infrared spectrum data of the modeling sample.

[0047] The near-infrared spectrometer can directly insert the probe into the modeled sample to measure the near-infrared spectral data. It is not affected by high temperature and has relatively high measurement accuracy. It does not require additional operations such as crystallization and titration, and can achieve in-situ analysis.

[0048] S20, pipetting a set volume of a component solution from the modeling sample, and obtaining a solution mass and a molar concentration of the component solution;

[0049] Specifically, at least one portion of the solution having a set volume can be transferred to each modeling sample, and then multiple portions of the solution having a set volume can be transferred to multiple modeling samples.

[0050] As a part of the modeling sample, the amount of the component solution is smaller than the amount of the modeling sample, which can save measurement time and resources and reduce resource waste.

[0051] S30, obtaining the mass fraction of ammonium nitrate in the modeling sample based on the solution mass and molar concentration of the component solution;

[0052] The component solution is a part of the modeling sample. The mass fraction of ammonium nitrate in the component solution is the same as the mass fraction of ammonium nitrate in the modeling sample. The mass fraction of ammonium nitrate in the component solution can be calculated by the solution mass and molar concentration of the component solution, and the mass fraction of ammonium nitrate in the modeling sample can be known.

[0053] S40, establishing a prediction model based on the correspondence between the near-infrared spectral data and the mass scores of the plurality of modeling samples;

[0054] That is, the prediction model includes the correspondence between the near-infrared spectral data and the mass scores.

[0055] S50, obtaining near infrared spectrum data of the sample to be tested by the near infrared spectrometer;

[0056] Specifically, the sample to be tested may be measured by a near infrared spectrometer to obtain near infrared spectrum data of the sample to be tested.

[0057] It can be understood that the modeling sample, the component solution and the sample to be tested are all aqueous solutions of ammonium nitrate.

[0058] S60. Based on the prediction model and the near-infrared spectrum data of the sample to be tested, the mass fraction of ammonium nitrate in the sample to be tested is obtained.

[0059] Specifically, the near infrared spectrum data of the sample to be tested can be substituted into the prediction model, and the mass fraction of ammonium nitrate in the sample to be tested can be obtained according to the near infrared spectrum data in the prediction module.

[0060] A prediction model is established through steps S10, S20, S30 and S40, and the mass fraction of ammonium nitrate in the sample to be tested is determined through steps S50 and S60.

[0061] Different prediction models can be established according to needs. By establishing a prediction model, the mass fraction of ammonium nitrate in the sample to be tested can be obtained by measuring the near-infrared spectrum data of the sample to be tested each time. Each measurement takes about 2 minutes, and the mass fraction of ammonium nitrate solution from 0% to 100% can be predicted. The measurement range is wide and the measurement speed is fast.

[0062] It is to be understood that the mass fractions in the present application all refer to the mass fraction of ammonium nitrate in the ammonium nitrate solution, that is, the percentage of the mass of ammonium nitrate to the mass of the ammonium nitrate solution.

[0063] The mass fraction determination method provided in the embodiment of the present application obtains the near-infrared spectral data of the modeling sample through a near-infrared spectrometer, obtains the true value of the mass fraction of ammonium nitrate in the modeling sample based on the solution mass and molar concentration of the component solution, and establishes a prediction model based on the correspondence between the near-infrared spectral data and the mass fraction. After the prediction model is established, it is only necessary to collect the near-infrared spectral data of the sample to be tested with an unknown mass fraction each time, and bring the near-infrared spectral data into the prediction model to obtain the mass fraction of ammonium nitrate in the sample to be tested, which is simple and convenient to operate.

[0064] The spectrum collection conditions of the infrared spectrometer can be selected according to needs. For example, in some embodiments, the collection conditions are: resolution is 8cm-1, spectrum collection range is 4000cm-1 to 10000cm-1, spectrum collection times is 64 times, and the probe optical path is 1mm (millimeter).

[0065] In some embodiments, the molarity of the aliquot solutions is determined by potentiometric titration.

[0066] Potentiometric titration is a titration method that uses a sudden change in solution potential to indicate the endpoint.

[0067] In this embodiment, the potentiometric titration has the characteristics of high accuracy and easy implementation of continuous, automatic and micro titration. The amount of ammonium nitrate in the component solution is relatively small, which can reduce the amount of titrant used and save resources.

[0068] In some embodiments, obtaining the molar concentration of the component solution by potentiometric titration comprises:

[0069] S210, adding a titrant of a set concentration dropwise to the component solution;

[0070] The titrant is a reagent that can react chemically with ammonium nitrate and change the potential of the ammonium nitrate solution.

[0071] The set concentration of the titrant is a known value.

[0072] Exemplarily, the titrant includes, but is not limited to, a standard sodium hydroxide solution of a set concentration.

[0073] S220, obtaining the titration volume of the titrant corresponding to the potential jump;

[0074] The titration volume refers to the volume of titrant consumed corresponding to the potential jump.

[0075] S230. Obtain the molar concentration of the component solution based on the set concentration of the titrant and the titration volume.

[0076] Specifically, the set concentration of the titrant is represented by C0, the unit is mol / L, and the titration volume of the titrant is represented by V i , the unit is mL, and the molar concentration of the component solution is expressed as C i , the unit is mol / L, the set volume of the component solution is expressed as V0, the unit is mL, then the molar concentration of the component solution can be calculated by the following formula (1):

[0077]

[0078] Potentiometric titration can be performed using a potentiometric titrator to achieve automated measurement.

[0079] In some embodiments, the mass of the solution of the portioned solution is obtained by weighing.

[0080] The instrument used for weighing is not limited, and for example, it can be weighed by a balance or other instruments.

[0081] In this embodiment, the solution mass of the component solution is obtained by weighing, which is simple to operate and easy to implement.

[0082] In some embodiments, the prediction model is a partial least squares model.

[0083] The Partial Least Squares (PLS) model is a statistical method used to process multivariate data, especially for the problem of multicollinearity between independent variables. The PLS model performs regression analysis by projecting the independent and dependent variables into a new space and finding the best linear relationship between them.

[0084] In some embodiments, the mass fraction determination method comprises:

[0085] S70, preparing an ammonium nitrate solution in a first container;

[0086] S80. Configure a plurality of the modeling samples based on the ammonium nitrate solution in the first container.

[0087] Specifically, before implementing step S10, steps S70 and S80 may be implemented first.

[0088] In this embodiment, multiple modeling samples are configured using the ammonium nitrate solution in a first container, which is simple to operate and easy to implement.

[0089] The type of the first container is not limited, and the first container may have scale or no scale.

[0090] Exemplarily, the first container can be a beaker or other containers with an opening on the top.

[0091] In some embodiments, the ammonium nitrate solution is prepared in the first container, comprising:

[0092] S701, adding ammonium nitrate solid and deionized water to the first container to prepare an initial solution, and continuously heating the initial solution to maintain the initial solution at a preset temperature;

[0093] The preset temperature can be set according to the requirements. For example, the preset temperature can be between 100°C (degrees Celsius) and 115°C. For example, the preset temperature can be 100°C, 105°C, 110°C, 112°C, 114°C or 115°C, etc. The preset temperature is within this range, which is convenient for taking into account the production process requirements of ammonium nitrate and the heating energy consumption.

[0094] Heating can promote the dissolution of ammonium nitrate solid in deionized water and save modeling time.

[0095] The initial solution may be a solution in which part of the ammonium nitrate solid is dissolved and another part is not dissolved.

[0096] S702, adding deionized water to the initial solution until the ammonium nitrate in the initial solution is completely dissolved.

[0097] Exemplarily, the initial solution is continued to be heated, and when the undissolved ammonium nitrate solid in the first container no longer decreases, deionized water is added until the ammonium nitrate solid in the first container is just completely dissolved, that is, deionized water is added to the initial solution until a saturated solution is obtained. The heating can be maintained for a set time until the solution in the first container is completely clarified, that is, the ammonium nitrate solid in the first container is ensured to be completely dissolved.

[0098] In this embodiment, the ammonium nitrate solid can be dissolved in two steps, and the ammonium nitrate solution can be prepared in the first container, so that the ammonium nitrate solution in the first container approaches a saturated solution, thereby reducing the measurement error. The influence of temperature is taken into account in the modeling process, so that the measurement can be performed under high temperature conditions, and the final measurement result is also good, and the maximum relative error can be no more than 5%.

[0099] In some embodiments, the mass fraction of ammonium nitrate in the initial solution is between 60% and 98%. Exemplarily, the mass fraction of ammonium nitrate in the initial solution is 60%, 65%, 70%, 80%, 85%, 90%, 95%, 98%, etc.

[0100] In this embodiment, the mass fraction of ammonium nitrate in the initial solution is moderate, which not only facilitates the configuration of multiple modeling samples with appropriate mass fraction interval distribution, thereby improving the accuracy and reliability of the prediction model, but also facilitates the relatively rapid dissolution of ammonium nitrate solids, thereby improving efficiency.

[0101] In some embodiments, configuring a plurality of the modeling samples based on the ammonium nitrate solution in the first container comprises:

[0102] S801, preparing a plurality of second containers of deionized water having a preset volume;

[0103] That is to say, the second container contains a preset volume of deionized water, and the preset volume can be set according to demand.

[0104] The type of the second container is not limited. For example, the second container may have scale or may not have scale.

[0105] Exemplarily, the second container may include a cover and a shell, the shell being a hollow structure with one end open, and the cover may close the opening at one end of the shell to form a closed container. In this way, the volatilization of the liquid in the second container may be reduced, and the risk of spillage and leakage of the liquid in the second container may be reduced. For example, the second container may be a centrifuge tube or other container with a cover.

[0106] S802, performing a pipetting step, specifically comprising: transferring a set volume of the component solution from the first container to the second container each time, and after removing the set volume of the component solution each time, adding deionized water to the first container to form the next modeling sample;

[0107] S803, repeat the pipetting step to obtain a plurality of the modeling samples, and obtain a plurality of second containers having the preset volumes of deionized water and the set volumes of the component solutions.

[0108] The device for transferring the solution in portions is not limited. For example, the solution in portions can be transferred by a pipette or other device.

[0109] The ammonium nitrate solution in the first container is used as a modeling sample, and a set volume of the component solution is transferred into the second container each time. The mass fraction of the component solution is the same as the mass fraction of the current modeling sample in the first container.

[0110] After removing a portion of the solution from the current modeling sample each time, deionized water is added to the first container to dilute the ammonium nitrate in the first container, thereby changing the mass fraction of the ammonium nitrate in the first container to serve as the next modeling sample. In this way, the pipetting step is repeated to pipette the diluted portion of the modeling sample in the first container into another second container.

[0111] Step S801 may be implemented first, and then step S802 may be repeatedly implemented to complete the configuration of multiple modeling samples.

[0112] Since the near-infrared spectral data of the modeling sample is collected, that is, the near-infrared spectral data of the ammonium nitrate solution in the first container is collected, during measurement, it is only necessary to insert the probe of the near-infrared spectrometer below the liquid level of the sample to be measured, that is, keep the probe inserted below the liquid level in the first container. There is no need to transfer or destroy the modeling sample during measurement, and in-situ analysis can be performed.

[0113] In this embodiment, the second container is used to hold the component solution, so as to detect the solution mass and molar concentration of the component solution, thereby obtaining the mass fraction of the corresponding modeling sample through the component solution. The same first container is always used to realize the configuration of multiple modeling samples, which can reduce the error caused by replacing the instrument, and the probe of the infrared spectrometer can be kept inserted into the same first container. The heating device can continue to heat the first container, and there is no need to change the measurement position of the probe of the infrared spectrometer, so as to realize in-situ analysis, improve accuracy and reliability, and simplify the operation process.

[0114] The type of the heating device is not limited. For example, the heating device may be an oil bath heater, which has the characteristic of uniform heating.

[0115] In some embodiments, removing a set volume of a component solution from the modeling sample and obtaining the solution mass and molar concentration of the component solution comprises:

[0116] S201, preparing a second container of deionized water with a preset volume;

[0117] S202, obtaining a first mass of a second container having the preset volume of deionized water;

[0118] S203, transferring a set volume of the component solution from the modeling sample to the second container;

[0119] S204, obtaining a second mass of a second container having the preset volume of deionized water and the set volume of the component solution;

[0120] S205. Obtain the solution mass of the component solution based on the second mass and the first mass.

[0121] Steps S201, S202, S203, S204 and S205 may be implemented in sequence. Step S201 and step S801 are the same step. In the process of repeatedly implementing step S802, component solutions of multiple modeling samples may be obtained. By implementing steps S202, S203, S204 and S205, the solution masses of multiple component solutions may be obtained. In other words, in the process of configuring multiple modeling samples based on the ammonium nitrate solution in the first container, the solution masses of multiple component solutions may be obtained.

[0122] Specifically, the first mass and the second mass can be obtained by weighing, and the difference between the second mass and the first mass is the mass of the solution.

[0123] Exemplarily, the second container of deionized water having a preset volume may be weighed by a balance to obtain the first mass.

[0124] Exemplarily, a second container having a preset volume of deionized water and a set volume of the portion solution may be weighed by a balance to obtain the second mass.

[0125] In this embodiment, in the process of configuring multiple modeling samples based on the ammonium nitrate solution in the first container, the solution masses of multiple component solutions can be obtained, and the operation is simple and convenient.

[0126] In some embodiments, removing a set volume of a component solution from the modeling sample and obtaining the solution mass and molar concentration of the component solution comprises:

[0127] S206, obtaining the molar concentration of the component solution by potentiometric titration of the component solution in the second container.

[0128] Exemplarily, step S206 may be implemented after step S205 is implemented.

[0129] The specific potentiometric titration operation can be implemented as described above and will not be repeated here.

[0130] In this embodiment, potentiometric titration has the characteristics of high accuracy and easy to realize continuous, automatic and micro titration. By potentiometric titration of the component solution in the second container, there is no need to operate on the modeling sample in the first container. The amount of ammonium nitrate in the component solution is relatively small, which can reduce the amount of titrant and save resources. The second container can also be moved to other locations for weighing as needed before performing the titration operation. The operation is simple and easy to implement.

[0131] The following is a specific example to further illustrate the mass fraction determination method provided in the embodiment of the present application, which is specifically described as follows:

[0132] S1. Use a beaker as a first container to weigh a certain mass of ammonium nitrate solid, and add a certain mass of deionized water so that the mass fraction of the initial solution in the beaker is about 95%. It is understandable that the mass of the ammonium nitrate solid and the mass of the deionized water can be selected according to demand, and the mass fraction of the initial solution in the beaker can be determined by estimation.

[0133] S2. Place the beaker in an oil bath and heat it. Control the temperature of the oil bath to maintain the preset temperature of the liquid in the beaker within a certain range, such as between 100°C and 115°C. When the ammonium nitrate solid in the beaker is mostly dissolved, insert the near-infrared spectrum probe into the initial solution in the beaker, and keep the mirror surface of the probe below the liquid surface. This design can preheat the probe so that the probe reaches the same temperature as the liquid in the beaker as soon as possible.

[0134] S3. Continue heating. When the undissolved ammonium nitrate solid in the beaker stops decreasing, add deionized water until the ammonium nitrate solid in the beaker is completely dissolved. Keep heating for a while until the solution in the beaker is observed to be completely clear. In this way, the ammonium nitrate solution in the beaker is used as the first modeling sample.

[0135] S4. Use a centrifuge tube as the second container, add 1.9 mL of deionized water into the centrifuge tube, use a balance to weigh the first mass of the centrifuge tube with 1.9 mL of deionized water and record it as M. i (The unit can be g, i.e., grams). The probe remains in the beaker, and the near-infrared spectrum data of the modeled sample in the beaker can be measured. Use a pipette to transfer a set volume of 100 μL (microliter) of the fraction solution from the beaker to the centrifuge tube, mix well, and use a balance to weigh the second mass of the centrifuge tube with 1.9 mL of deionized water and 100 μL of the fraction solution again and record M i '(unit: g), at this time, the mass M of the component solution can be obtained according to the calculation formula (2): 分i (unit: g), where formula (2) is

[0136] M 分i =M i '-M i (2)

[0137] S5. After transferring a set volume of 100 μL (microliter) of the solution into the centrifuge tube, deionized water can be added to the beaker to form the next modeling sample. It can be understood that the amount of deionized water can be added according to demand. Since the beaker is always in a heated state, the amount of deionized water added each time can be increased successively as time goes by.

[0138] The beaker was gently shaken to mix the solution. After standing for 1 minute, step S4 was repeated again. Steps S4 and S5 were continuously repeated until a plurality of modeling samples and component solutions were obtained, and the near-infrared spectral data of the modeling samples, as well as the solution mass and molar concentration of the component solutions were obtained.

[0139] S6. Use a potentiometric titrator to titrate each portion of the solution in each centrifuge tube. The titrant is a standard sodium hydroxide solution of known concentration. The set concentration of the standard sodium hydroxide solution is represented by C0 in mol / L. The set volume of the portion of solution is represented by V0 in mL. The consumption of the titrant corresponding to the potential jump of each portion of the solution is recorded, i.e., the titration volume. The titration volume of the titrant is represented by V. i , unit is mL), then the molar concentration C of the component solution can be obtained according to the calculation formula (1) i , the unit is mol / L, and the calculation formula (1) is:

[0140]

[0141] Combined with the measured M 分i And the molecular weight of ammonium nitrate is 80.0434 g / mol (grams per mole), and the mass fraction ω of each modeling sample can be calculated according to formula (3): i for:

[0142]

[0143] According to all the near-infrared spectral data collected at the preset temperature and the mass fraction ω of the corresponding modeling sample i , establish a prediction model such as a partial least squares model.

[0144] S7. Collect near-infrared spectrum data of the sample to be tested, and bring the near-infrared spectrum data into the prediction model to obtain the mass fraction of ammonium nitrate in the sample to be tested.

[0145] The spectral acquisition conditions of the near-infrared spectral data of the above-mentioned modeling samples and the samples to be tested can be: a resolution of 8 cm-1, a spectral acquisition range of 4000 cm-1-10000 cm-1, spectral acquisition times of 64 times, and a probe optical path of 1 mm.

[0146] It is understandable that during the near-infrared spectral data collection process, the sample to be tested can also be heated by an oil bath or other means to maintain the temperature of the sample to be tested at a preset temperature, such as 100°C to 115°C.

[0147] In order to verify the accuracy of the mass fraction determination method provided in the embodiment of the present application, the present application adopts the mass fraction determination method to collect the near infrared spectra of a series of verification samples of ammonium nitrate solutions with different concentrations. The mass fraction of ammonium nitrate in the verification samples is between 72% and 96%. The preset temperature during the verification sample determination process is controlled between 100°C and 115°C. The determination results are shown in Figure 2 , Figure 2In the figure, the horizontal axis represents the true value of mass fraction, the vertical axis represents the relative deviation between the true value of mass fraction and the predicted value of mass fraction obtained according to the prediction model, the ○ series is the modeling sample, and the + series is the verification sample. The results show that the relative deviation of both the modeling sample and the verification sample is less than 2%, the mass fraction prediction value is relatively accurate, and the R2 value of the prediction model is 0.99. R2, the determination coefficient, is used to measure the goodness of fit of the prediction model. The R2 value of 0.99 indicates that the prediction model has a good fit to the data, which further illustrates that the performance of the prediction model is relatively excellent and can accurately predict the mass fraction of ammonium nitrate.

[0148] In the description of this specification, the description with reference to the terms "an embodiment", "some embodiments" and "exemplary" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0149] The various embodiments / implementations provided in this application can be combined with each other without causing any contradiction. The above description is only a preferred embodiment of this application and is not intended to limit this application. For those skilled in the art, this application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included in the protection scope of this application.

Claims

1. A method for determining the mass fraction of ammonium nitrate in an ammonium nitrate solution, characterized in that: include: Acquiring near infrared spectral data of a plurality of modeling samples by a near infrared spectrometer, wherein the plurality of modeling samples are ammonium nitrate solutions of a plurality of different concentrations; Pipetting a set volume of a component solution from the modeling sample, and obtaining a solution mass and a molar concentration of the component solution; Obtaining the mass fraction of ammonium nitrate in the modeling sample based on the solution mass and molar concentration of the component solution; Establishing a prediction model based on the correspondence between the near-infrared spectral data and the mass scores of the plurality of modeling samples; Acquire near infrared spectrum data of the sample to be tested by the near infrared spectrometer; Based on the prediction model and the near-infrared spectrum data of the sample to be tested, the mass fraction of ammonium nitrate in the sample to be tested is obtained.

2. The mass fraction determination method according to claim 1, characterized in that: The mass fraction determination method comprises: Disposing an ammonium nitrate solution in a first container; A plurality of the modeling samples are configured based on the ammonium nitrate solution in the first container.

3. The mass fraction determination method according to claim 2, characterized in that: The ammonium nitrate solution is prepared in a first container, comprising: Adding ammonium nitrate solid and deionized water into the first container to prepare an initial solution, and continuously heating the initial solution to maintain the initial solution at a preset temperature; Deionized water was added to the initial solution until the ammonium nitrate in the initial solution was completely dissolved.

4. The mass fraction determination method according to claim 3, characterized in that: The mass fraction of ammonium nitrate in the initial solution is between 60% and 98%.

5. The mass fraction determination method according to claim 2, characterized in that: Configuring a plurality of the modeling samples based on the ammonium nitrate solution in the first container comprises: preparing a plurality of second containers of deionized water having a preset volume; Implementing the pipetting step specifically includes: each time transferring a set volume of the component solution from the first container to the second container, and after each removal of the set volume of the component solution, adding deionized water to the first container to form the next modeling sample; The pipetting step is repeatedly performed to obtain a plurality of the modeling samples and a plurality of second containers having the preset volumes of deionized water and the set volumes of the component solutions.

6. The mass fraction determination method according to claim 1, characterized in that: Pipetting a set volume of a component solution from the modeling sample and obtaining a solution mass and a molar concentration of the component solution include: preparing a second container with a preset volume of deionized water; obtaining a first mass of a second container of deionized water having the preset volume; Pipetting a set volume of aliquot solution from the modeling sample into the second container; obtaining a second mass of a second container having the preset volume of deionized water and the set volume of the component solution; The solution mass of the component solution is obtained based on the second mass and the first mass.

7. The mass fraction determination method according to claim 6, characterized in that: Pipetting a set volume of a component solution from the modeling sample and obtaining a solution mass and a molar concentration of the component solution include: The molar concentration of the component solution is obtained by potentiometric titration of the component solution in the second container.

8. The mass fraction determination method according to claim 1, characterized in that: The molar concentrations of the component solutions were obtained by potentiometric titration.

9. The mass fraction determination method according to claim 1, characterized in that: The mass of the solution of the portion is obtained by weighing.

10. The mass fraction determination method according to claim 1, characterized in that: The prediction model is a partial least squares model.

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