Method for rapidly measuring saponification value of rolling oil in emulsified liquid for cold rolling production

Abstract

The invention discloses a method for rapidly measuring the saponification value of rolling oil in emulsified liquid for cold rolling production, which comprises the following steps: preparing and measuring cold rolling oil standard samples with different saponification values in advance, and obtaining a correlation curve of the corresponding wave band number and absorbance; screening and recording correlation curves of the cold rolling oil standard samples with different saponification values; the method comprises the following steps: taking cold rolling emulsion for field production, filtering and removing smudginess; adding an organic solvent into the cold rolling emulsion, then stirring and mixing, performing centrifugal separation, taking clear liquid of an upper organic solvent phase, and performing negative pressure rotary evaporation to obtain a rolling oil sample to be detected; matching and fitting the correlation curves of the cold rolling oil standard samples with different saponification values with the correlation curve of the rolling oil sample to be detected one by one to obtain the saponification value of the rolling oil sample to be detected. According to the method, the saponification value of the rolling oil in the cold rolling emulsion can be rapidly obtained on site, and a proper amount of emulsion is supplemented to a cold rolling production unit in time.

Description

Technical Field

[0001] The invention relates to the technical field of saponification value determination, and in particular to a method for quickly measuring the saponification value of rolling oil in an emulsion used in cold rolling production. Background Art

[0002] Modern steel production enterprises usually need to perform cold rolling on some steel materials. The cold rolling production units need to be equipped with emulsions for processing during the cold rolling process. Specifically, industrial desalted water and rolling oil are configured into a liquid with a concentration of ≤5%, and the liquid is sprayed onto the strip and rolls. Since the emulsion has excellent lubrication and cooling effects, the wear of the rolls, the energy consumption of the rolling mill, and the surface quality of the strip all depend on the performance of the emulsion. In cold rolling production, a large number of tests on the emulsion are required. The performance of the emulsion includes many aspects. Common test items are the saponification value and acid value tests of the rolling oil in the emulsion.

[0003] Saponification value is one of the most important routine tests for evaluating oil performance. It indicates the mass of potassium hydroxide required to completely saponify 1g of oil. From a chemical point of view, it indicates the content of free and combined fatty acids and esters in the oil sample. The test of saponification value is mainly used to determine the degree of mixing of various hydraulic oils, greases, mechanical lubricants and other miscellaneous oils in the cold rolling production unit. If the saponification value is found to be too low, the emulsion must be sprayed and supplemented immediately, otherwise the production quality and various product defects will be difficult to guarantee.

[0004] In summary, since emulsions are commonly used in cold rolling production, and the rolling oil is detected, when the cold rolling emulsion is tested, it is first necessary to separate the oil and water of the cold rolling emulsion used in the on-site production to obtain the rolling oil. This process generally requires adding a large amount of sodium chloride to the emulsion, and then heating it to above 80°C to accelerate the oil-water stratification speed. The oil-water separation phenomenon will only occur after a long period of operation. Then, the oil phase is sampled and dissolved with an organic solvent to extract the rolling oil. The extract is then sampled and heated to remove the organic solvent, and the rolling oil sample is finally obtained; then, a standard potassium hydroxide solution is titrated, and in this process, a phenolphthalein indicator is used to perform the coordinated indication of the reaction end point. The above process is time-consuming and laborious, usually requiring 3 to 5 hours of operation, and the titration operation of the required reagents must be measured in the laboratory. In actual production conditions, it often takes more than one day from sampling to obtaining the final titration result, and it is difficult to meet the demand for rapid adjustment on the production unit.

[0005] For example, the technical document of the patent application No. JP2001281232A published in Japan proposes a method for measuring and controlling the saponification value of rolling oil in emulsion, wherein chemical hydrochloric acid is added to the emulsion to destroy the emulsifier and separate the oil and water, and the rolling oil in the upper liquid is obtained, and the saponification value of the rolling oil is detected by infrared detection equipment. In specific operation, the overall detection process can be controlled within 1 hour. The biggest feature of this method is that hydrochloric acid can destroy the emulsion very quickly, realize oil-water separation, and obtain rolling oil, but hydrochloric acid will play an additional role in accelerating the decomposition of oil in the rolling oil when used. Therefore, in the subsequent infrared spectrum measurement, the obtained result will have a large deviation from the true saponification value. At the same time, the rolling oil will inevitably be mixed with iron powder and water during the measurement sampling, and the error caused in the infrared detection will be more significant.

[0006] Therefore, there is an urgent need for a technical method that can quickly extract the emulsion used in the cold rolling production site, quickly measure the saponification value of the rolling oil therein, and simplify the measurement process operation. Summary of the invention

[0007] The object of the present invention is to provide a method for quickly measuring the saponification value of rolling oil in the emulsion used for cold rolling production, which can obtain the saponification value of the cold rolling emulsion at the cold rolling production site and timely supplement the cold rolling production unit with an appropriate amount of emulsion to meet the needs of rapid measurement and rapid adjustment on site.

[0008] In order to achieve the above object, the present invention adopts the following technical solution: A method for quickly measuring the saponification value of rolling oil in an emulsion for cold rolling production comprises the following steps: Step 1: Turn on the Fourier transform infrared spectrometer and continuously purge the Fourier transform infrared spectrometer with high-purity nitrogen until the Fourier transform infrared spectrometer shows no interference peaks; Step 2: Take unused cold-rolled oil crude oil samples and perform two different pretreatments on the cold-rolled oil crude oil samples, respectively as follows: Pretreatment 1: Take an appropriate amount of cold-rolled oil crude oil sample and put it into a clean sample pool to obtain a standard oil sample; Pretreatment 2: Take a cold-rolled oil crude oil sample, put it into a clean sample pool, add mineral oil to the middle position of the cold-rolled oil crude oil sample, heat it to 50° C. and mix it thoroughly to obtain a mixed oil sample, wherein the mass percentage of the cold-rolled oil crude oil sample and the mineral oil in the mixed oil sample is: 6-9:1-4; Wherein, the pretreatment step 2 is repeated at least four times; After pretreatment 1 and pretreatment 2 are completed, the sample pool is purged with high-purity nitrogen for 10 minutes; Step 3: Use Fourier transform infrared spectrometer to perform infrared spectrum scanning on the standard oil sample and the mixed oil sample respectively. The infrared spectrum scanning of a single sample is repeated multiple times, and a blank scan is performed before each sample scanning to obtain the infrared spectrum of the standard oil sample and the infrared spectrum of the mixed oil sample; Step 4: Use titration method to measure the saponification values ​​of the standard oil sample and the mixed oil sample respectively, and record the saponification values ​​of the standard oil sample and the mixed oil sample; Step 5: Open the infrared spectrum data processing software, preset the band number range on the infrared spectrum data processing software, input the infrared spectra and saponification values ​​of the standard oil sample and the mixed oil sample into the infrared spectrum data processing software in sequence, output the corresponding correlation curve between the band number and the absorbance, and assign a value to the maximum peak height of the absorbance within the band number range, wherein the band number range is set to 1710-1780cm -1 ; Step 6: Use infrared spectrum data processing software to pre-analyze the correlation curves of the standard oil sample and the mixed oil sample, and automatically calculate the correlation coefficient of the corresponding saponification value. If the correlation coefficient of the saponification value of the sample reaches 0.995 or above, it is determined that its correlation curve meets the standard curve requirements and is saved for later use. Otherwise, it is determined that its correlation curve does not meet the standard curve requirements, and returns to step 2 to re-acquire the relevant data of the standard oil sample or the mixed oil sample until there is a standard oil sample and at least four mixed oil samples whose correlation curves all meet the standard curve requirements; Step 7: Take the cold-rolled emulsion used in on-site production, filter the cold-rolled emulsion, and remove dirt in the cold-rolled emulsion; Step 8: adding an organic solvent to the filtered cold-rolled emulsion, and then placing it in a high-speed stirrer and stirring for 5 to 10 minutes at a stirring speed of 8000 rpm to obtain a mixture of the cold-rolled emulsion and the organic solvent, wherein the amount of the organic solvent added is 40 to 100 ml; Step nine: placing the mixture of the cold-rolled emulsion and the organic solvent into a plurality of polypropylene centrifuge tubes, and then centrifuging them on a high-speed centrifuge for 5 to 15 minutes to obtain a mixed centrifugal liquid; Step 10: taking the clear liquid of the upper organic solvent phase from the mixed centrifuged liquid, placing the clear liquid in a rotary evaporator for negative pressure rotary evaporation, and obtaining a rolling oil sample to be tested after the organic solvent and trace water are completely evaporated and removed; Step 11: Take an appropriate amount of rolling oil sample to be tested, put it into a clean sample pool, and use a Fourier transform infrared spectrometer to perform infrared spectrum scanning on the rolling oil sample to be tested. The infrared spectrum scanning of a single sample is repeated multiple times, and a blank scan is performed before each sample scanning to obtain the infrared spectrum of the rolling oil sample to be tested; Step 12: Input the infrared spectrum of the rolling oil sample to be tested into the infrared spectrum data processing software to obtain the correlation curve between the corresponding band number and absorbance. Then, the infrared spectrum data processing software uses a linear interpolation fitting algorithm to pair and fit the correlation curves of the standard oil sample and the mixed oil sample with the correlation curve of the rolling oil sample to be tested, and obtain the saponification value of the rolling oil sample to be tested.

[0009] Preferably, in step 1 and step 2, the flow rate of the high-purity nitrogen is controlled to be 30 mL / min.

[0010] Preferably, in step 2, the mineral oil is Kunlun L-HM46 hydraulic oil.

[0011] Preferably, in step three and step eleven, the number of infrared spectrum scans of the single sample is set to 32 times.

[0012] Preferably, in the step seven, the sampling amount of the cold-rolled emulsion is 400-800 ml, and the concentration of the cold-rolled emulsion is above 1.5%.

[0013] Preferably, in the step seven, the cold-rolled emulsion is filtered using a microporous filter, and the micropore diameter of the filter membrane of the microporous filter is 0.45 μm.

[0014] Preferably, in step eight, the organic solvent is one of a mixed solvent of isopropanol and petroleum ether, butanone, and ethylene dichloride, wherein the volume ratio of isopropanol to petroleum ether in the mixed solvent is 1:2.

[0015] Preferably, in step nine, the number of the polypropylene centrifuge tubes is 2 to 8, and the volume of the mixed solution in each polypropylene centrifuge tube is controlled to be 15 ml.

[0016] Preferably, in the step 10, the clear liquid of the upper organic solvent phase is subjected to negative pressure rotary evaporation in a hot water bath at 60-85° C. and a negative pressure of -640 mm Hg.

[0017] The beneficial effects of the present invention are: 1. This method can quickly extract the rolling oil from the cold rolling emulsion used by the on-site cold rolling production unit, and can also efficiently remove impurities and trace water contained in the rolling oil, ensuring the accuracy of the measurement of the saponification value of the rolling oil.

[0018] 2. This method prepares and measures cold rolling oil standard samples with different saponification values ​​in advance, compares and fits the cold rolling oil standard samples with the rolling oil with the saponification value to be measured, quickly obtains the saponification value of the rolling oil in the on-site cold rolling emulsion, improves the measurement accuracy of the saponification value of the rolling oil, and then quickly obtains the real-time status of the on-site cold rolling emulsion, and promptly adjusts the addition of emulsion for the on-site cold rolling production unit, which has high practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a correlation curve diagram based on the infrared spectrum of 1# standard sample in the embodiment of the present invention.

[0020] Figure 2 It is a correlation curve diagram based on the infrared spectrum of 2# standard sample in the embodiment of the present invention.

[0021] Figure 3 It is a correlation curve diagram based on the infrared spectrum of 3# standard sample in the embodiment of the present invention.

[0022] Figure 4 It is a correlation curve diagram based on the infrared spectrum of 4# standard sample in the embodiment of the present invention.

[0023] Figure 5 It is a correlation curve diagram based on the infrared spectrum of 5# standard sample in the embodiment of the present invention.

[0024] Figure 6 It is a standard curve diagram of saponification value in the examples of the present invention.

[0025] Figure 7 It is a correlation curve diagram based on the infrared spectrum of the rolling oil sample to be tested in the embodiment of the present invention. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention will be described below with reference to the accompanying drawings.

[0027] A method for quickly measuring the saponification value of rolling oil in an emulsion for cold rolling production comprises the following steps: Step 1: Turn on the Fourier transform infrared spectrometer and continuously purge the Fourier transform infrared spectrometer with high-purity nitrogen until the Fourier transform infrared spectrometer shows no interference peaks; Step 2: Take unused cold-rolled oil crude oil samples and perform two different pretreatments on the cold-rolled oil crude oil samples, respectively as follows: Pretreatment 1: Take an appropriate amount of cold-rolled oil crude oil sample and put it into a clean sample pool to obtain a standard oil sample; Pretreatment 2: Take a cold-rolled oil crude oil sample, put it into a clean sample pool, add mineral oil to the middle position of the cold-rolled oil crude oil sample, heat it to 50° C. and mix it thoroughly to obtain a mixed oil sample, wherein the mass percentage of the cold-rolled oil crude oil sample and the mineral oil in the mixed oil sample is: 6-9:1-4; Wherein, the pretreatment step 2 is repeated at least four times; After pretreatment 1 and pretreatment 2 are completed, the sample pool is purged with high-purity nitrogen for 10 minutes; Step 3: Use Fourier transform infrared spectrometer to perform infrared spectrum scanning on the standard oil sample and the mixed oil sample respectively. The infrared spectrum scanning of a single sample is repeated multiple times, and a blank scan is performed before each sample scanning to obtain the infrared spectrum of the standard oil sample and the infrared spectrum of the mixed oil sample; Step 4: Use titration method to measure the saponification values ​​of the standard oil sample and the mixed oil sample respectively, and record the saponification values ​​of the standard oil sample and the mixed oil sample; Step 5: Open the infrared spectrum data processing software, preset the band number range on the infrared spectrum data processing software, input the infrared spectra and saponification values ​​of the standard oil sample and the mixed oil sample into the infrared spectrum data processing software in sequence, output the corresponding correlation curve between the band number and the absorbance, and assign a value to the maximum peak height of the absorbance within the band number range, wherein the band number range is set to 1710-1780cm -1 ; Step 6: Use infrared spectrum data processing software to pre-analyze the correlation curves of the standard oil sample and the mixed oil sample, and automatically calculate the correlation coefficient of the corresponding saponification value. If the correlation coefficient of the saponification value of the sample reaches 0.995 or above, it is determined that its correlation curve meets the standard curve requirements and is saved for later use. Otherwise, it is determined that its correlation curve does not meet the standard curve requirements, and returns to step 2 to re-acquire the relevant data of the standard oil sample or the mixed oil sample until there is a standard oil sample and at least four mixed oil samples whose correlation curves all meet the standard curve requirements; Step 7: Take the cold-rolled emulsion used in on-site production, filter the cold-rolled emulsion, and remove dirt in the cold-rolled emulsion; Step 8: adding an organic solvent to the filtered cold-rolled emulsion, and then placing it in a high-speed stirrer and stirring for 5 to 10 minutes at a stirring speed of 8000 rpm to obtain a mixture of the cold-rolled emulsion and the organic solvent, wherein the amount of the organic solvent added is 40 to 100 ml; Step nine: placing the mixture of the cold-rolled emulsion and the organic solvent into a plurality of polypropylene centrifuge tubes, and then centrifuging them on a high-speed centrifuge for 5 to 15 minutes to obtain a mixed centrifugal liquid; Step 10: taking the clear liquid of the upper organic solvent phase from the mixed centrifuged liquid, placing the clear liquid in a rotary evaporator for negative pressure rotary evaporation, and obtaining a rolling oil sample to be tested after the organic solvent and trace water are completely evaporated and removed; Step 11: Take an appropriate amount of rolling oil sample to be tested, put it into a clean sample pool, and use a Fourier transform infrared spectrometer to perform infrared spectrum scanning on the rolling oil sample to be tested. The infrared spectrum scanning of a single sample is repeated multiple times, and a blank scan is performed before each sample scanning to obtain the infrared spectrum of the rolling oil sample to be tested; Step 12: Input the infrared spectrum of the rolling oil sample to be tested into the infrared spectrum data processing software to obtain the correlation curve between the corresponding band number and absorbance. Then, the infrared spectrum data processing software uses a linear interpolation fitting algorithm to pair and fit the correlation curves of the standard oil sample and the mixed oil sample with the correlation curve of the rolling oil sample to be tested, and obtain the saponification value of the rolling oil sample to be tested.

[0028] Preferably, in step 1 and step 2, the flow rate of the high-purity nitrogen is controlled to be 30 mL / min.

[0029] Preferably, in step 2, the mineral oil is Kunlun L-HM46 hydraulic oil.

[0030] Preferably, in step three and step eleven, the number of infrared spectrum scans of the single sample is set to 32 times.

[0031] Preferably, in the step seven, the sampling amount of the cold-rolled emulsion is 400-800 ml, and the concentration of the cold-rolled emulsion is above 1.5%.

[0032] Preferably, in the step seven, the cold-rolled emulsion is filtered using a microporous filter, and the micropore diameter of the filter membrane of the microporous filter is 0.45 μm.

[0033] Preferably, in step eight, the organic solvent is one of a mixed solvent of isopropanol and petroleum ether, butanone, and ethylene dichloride, wherein the volume ratio of isopropanol to petroleum ether in the mixed solvent is 1:2.

[0034] Preferably, in step nine, the number of the polypropylene centrifuge tubes is 2 to 8, and the volume of the mixed solution in each polypropylene centrifuge tube is controlled to be 15 ml.

[0035] Preferably, in the step 10, the clear liquid of the upper organic solvent phase is subjected to negative pressure rotary evaporation in a hot water bath at 60-85° C. and a negative pressure of -640 mm Hg.

[0036] It should be noted that steps 1 to 6 described in the present method are for pre-preparing and measuring the data of standard oil samples with different saponification values, and storing the relevant data in an electronic storage device for use, which can be repeatedly used for linear interpolation fitting with the rolling oil to be tested extracted on site to obtain the saponification value data corresponding to the rolling oil in the on-site cold rolling emulsion; steps 7 to 12 described in the present method are for collecting, extracting, infrared spectroscopy scanning, digitizing the relevant information and pairing fitting with the pre-prepared standard oil sample data of the cold rolling emulsion of the on-site cold rolling production unit. This part of the process can be implemented manually at the production site, so as to quickly obtain the real-time status of the on-site cold rolling emulsion, and at the same time ensure the accuracy of the saponification value measurement of the on-site cold rolling emulsion, and quickly adjust the addition of emulsion for the on-site cold rolling production unit in time, which has high practicality.

[0037] It can be understood that in step 4 of the present method, the titration method is an existing traditional method for determining the saponification value, but the existing method requires laboratory cooperation to implement, and can be specifically divided into acid-base titration and potentiometric titration; the principle of the acid-base titration method is to react the oil with potassium hydroxide or sodium hydroxide solution to generate corresponding fatty acid salts and glycerol, and then titrate the remaining alkali with hydrochloric acid or sulfuric acid to calculate the saponification value. The acid-base titration method is simple to operate and the results are accurate, but it consumes a large amount of chemical reagents and has high requirements for experimental conditions; the principle of the potentiometric titration method is to heat the oil to be tested and the excess potassium hydroxide ethanol solution to reflux to completely saponify the oil, and then titrate the remaining potassium hydroxide with a potentiometric titrator, determine the titration end point according to the potential change, and calculate the saponification value. The potentiometric titration method has high measurement accuracy and is easy to operate. It is suitable for automated detection, but has high requirements for experimental equipment.

[0038] It should be noted that in order to speed up the measurement and analysis time of the Fourier transform infrared spectrometer, the following operations can be prepared and implemented in advance for the relevant instruments: 1. Before scanning and measuring the sample, turn on the Fourier transform infrared spectrometer and purge the Fourier transform infrared spectrometer with high-purity nitrogen. The flow rate of high-purity nitrogen is controlled at 30mL / min. It only takes 20 minutes of purge to make the Fourier transform infrared spectrometer display no interference peaks. 2. The internal configuration of the Fourier transform infrared spectrometer is equipped with auxiliary software, which can control the high-speed scanning behavior of the Fourier transform infrared spectrometer. You can set a blank scan before each scan, and then set the number of scans to 32 times. When the infrared spectrum scan is actually performed, the Fourier transform infrared spectrometer will directly and automatically execute it to obtain the infrared spectrum of the corresponding sample.

[0039] The following will combine specific test data with the steps of this method to provide further technical explanation: First, before testing the rolling oil sample, prepare the basic paired samples required by this method in advance, as follows: 1. Take an appropriate amount of unused cold-rolled oil crude oil sample and put it into a clean sample pool to obtain a standard oil sample. First, perform infrared spectrum scanning and data processing on the standard oil sample. The correlation curve between the corresponding band number and absorbance is as follows: Figure 1 As shown, the saponification value of the standard oil sample is measured by titration method, and the saponification value is 154.4 mgKOH / g, and the standard oil sample is identified as 1# standard sample.

[0040] 2. Take unused cold rolling oil crude oil sample and Kunlun L-HM46 hydraulic oil, the mass percentage is controlled at 9:1, add Kunlun L-HM46 hydraulic oil to the middle position of the cold rolling oil crude oil sample, heat it to 50°C and mix it thoroughly to obtain a mixed oil sample. First, perform infrared spectroscopy scanning and data processing on the mixed oil sample. The correlation curve between the corresponding band number and absorbance is as follows: Figure 2 As shown, the saponification value of the mixed oil sample was measured by titration method, and the saponification value was 137.8 mgKOH / g, and the mixed oil sample was identified as 2# standard sample.

[0041] 3. Take unused cold rolling oil crude oil sample and Kunlun L-HM46 hydraulic oil, the mass percentage is controlled at 8:2, add Kunlun L-HM46 hydraulic oil to the middle position of the cold rolling oil crude oil sample, heat it to 50°C and mix it thoroughly to obtain a mixed oil sample. First, perform infrared spectroscopy scanning and data processing on the mixed oil sample. The correlation curve between the corresponding band number and absorbance is as follows: Figure 3 As shown, the saponification value of the mixed oil sample was measured by titration method, and the saponification value was 123.8 mgKOH / g, and the mixed oil sample was identified as 3# standard sample.

[0042] 4. Take unused cold rolling oil crude oil sample and Kunlun L-HM46 hydraulic oil, the mass percentage is controlled at 7:3, add Kunlun L-HM46 hydraulic oil to the middle position of the cold rolling oil crude oil sample, heat it to 50°C and mix it thoroughly to obtain a mixed oil sample. First, perform infrared spectroscopy scanning and data processing on the mixed oil sample. The correlation curve between the corresponding band number and absorbance is as follows: Figure 4 As shown, the saponification value of the mixed oil sample is measured by titration method, and the saponification value is 106.8 mgKOH / g, and the mixed oil sample is identified as 4# standard sample.

[0043] 5. Take unused cold rolling oil crude oil sample and Kunlun L-HM46 hydraulic oil, the mass percentage is controlled at 6:4, add Kunlun L-HM46 hydraulic oil to the middle position of the cold rolling oil crude oil sample, heat it to 50°C and mix it thoroughly to obtain a mixed oil sample. First, perform infrared spectroscopy scanning and data processing on the mixed oil sample. The correlation curve between the corresponding band number and absorbance is as follows: Figure 5 As shown, the saponification value of the mixed oil sample was measured by titration method, and the saponification value was 89.9 mgKOH / g, and the mixed oil sample was identified as 5# standard sample.

[0044] Finally, the above-configured standard samples are automatically calculated by infrared spectrum data processing software for the correlation coefficient of saponification value, and the infrared spectrum data processing software outputs the following Figure 6 The standard curve of saponification value shown is Figure 6 It can be seen that the correlation coefficient of the saponification value of each standard sample is 0.996, which meets the requirements of the standard curve. Therefore, the standard samples that have been configured above can be saved for use.

[0045] When it is necessary to measure the cold rolling emulsion on site, according to the steps of the method, the following operations are performed at a certain cold rolling production unit on site: Take the cold rolling emulsion used in the on-site production, the sampling volume of the cold rolling emulsion is controlled to be 500ml, and the concentration of the cold rolling emulsion is measured to reach 1.95%, which meets the requirements of the better concentration determination standard; The cold rolling emulsion is filtered through a microporous filter with a pore diameter of 0.45 μm to remove iron powder and oil stains contained in the cold rolling emulsion to avoid affecting the measurement accuracy of the saponification value of the rolling oil in the cold rolling emulsion; A mixed solvent of isopropanol and petroleum ether was added to the filtered cold-rolled emulsion, the amount of the mixed solvent added was 60 ml, and after simple mixing, the mixture was placed in a high-speed stirrer and stirred for 5 minutes at a stirring speed of 8000 rpm to obtain a mixed solution of the cold-rolled emulsion and the organic solvent; The mixed solution of the cold-rolled emulsion and the organic solvent is transferred into four polypropylene centrifuge tubes by using a pipette, and the mixed solution in each polypropylene centrifuge tube is controlled to be 15 ml, and then placed in a high-speed centrifuge for centrifugation for 10 minutes to obtain a mixed centrifugal liquid; The organic solvent in the polypropylene centrifuge tube will extract the rolling oil and gather it in the upper layer of the mixed centrifugal liquid. At this time, take the clear liquid of the upper organic solvent phase in the polypropylene centrifuge tube, the sampling volume is 40ml, put it in a rotary evaporator, and perform negative pressure rotary evaporation under the conditions of 80℃ hot water bath and negative pressure of -640mm mercury column to remove the organic solvent and trace water, and obtain the rolling oil sample to be tested; Take an appropriate amount of rolling oil sample to be tested, put it into a clean sample pool, and use Fourier transform infrared spectrometer to perform infrared spectrum scanning on the rolling oil sample to be tested. The infrared spectrum of a single sample is scanned 32 times, and a blank scan is performed before each sample scanning. The infrared spectrum of the rolling oil sample to be tested is input into the infrared spectrum data processing software to obtain the following Figure 7 The correlation curve of the rolling oil sample to be tested is shown in the figure, and then the infrared spectrum data processing software matches and fits the correlation curves of 1# standard sample, 2# standard sample, 3# standard sample, 4# standard sample and 5# standard sample with the correlation curve of the rolling oil sample to be tested according to the linear interpolation fitting algorithm, and then it can be concluded that the saponification value of the rolling oil sample to be tested is 123.5mgKOH / g; if the saponification value of the rolling oil sample to be tested is measured by titration, the saponification value obtained by the titration method implemented in the laboratory is 128.1mgKOH / g; from the comparison of the results, the saponification value determination of the cold rolling emulsion obtained by this method has high accuracy, based on the step flow of this method, in the whole operation process, the pre-preparation work of standard sample data and related instrument adjustment is removed, and the saponification value determination process of the cold rolling emulsion based on the field can be controlled within 1 hour and 30 minutes.

[0046] The implementation process of this method is simple, and only a certain amount of manpower is needed for manual operation, and relevant standard sample data is prepared in advance and the setting operation of relevant instruments is adjusted, so that the saponification value of the rolling oil in the on-site cold rolling emulsion can be measured more accurately, especially the influence of iron powder and moisture brought by on-site emulsion sampling can be reduced, and the actual measurement operation time can be basically controlled within 1 hour and 30 minutes, and the real-time status of the on-site cold rolling emulsion can be quickly obtained, and the on-site unit can be guided to quickly adjust the on-site emulsion replenishment, and it does not need to be matched with laboratory equipment, and has extremely high practicality.

Claims

1. A method for quickly measuring the saponification value of rolling oil in an emulsion for cold rolling production, characterized in that: The following steps are involved: Step 1: Turn on the Fourier transform infrared spectrometer and continuously purge the Fourier transform infrared spectrometer with high-purity nitrogen until the Fourier transform infrared spectrometer shows no interference peaks; Step 2: Take unused cold-rolled oil crude oil samples and perform two different pretreatments on the cold-rolled oil crude oil samples, respectively as follows: Pretreatment 1: Take an appropriate amount of cold-rolled oil crude oil sample and put it into a clean sample pool to obtain a standard oil sample; Pretreatment 2: Take a cold-rolled oil crude oil sample, put it into a clean sample pool, add mineral oil to the middle position of the cold-rolled oil crude oil sample, heat it to 50° C. and mix it thoroughly to obtain a mixed oil sample, wherein the mass percentage of the cold-rolled oil crude oil sample and the mineral oil in the mixed oil sample is: 6-9:1-4; Wherein, the pretreatment step 2 is repeated at least four times; After pretreatment 1 and pretreatment 2 are completed, the sample pool is purged with high-purity nitrogen for 10 minutes; Step 3: Use Fourier transform infrared spectrometer to perform infrared spectrum scanning on the standard oil sample and the mixed oil sample respectively. The infrared spectrum scanning of a single sample is repeated multiple times, and a blank scan is performed before each sample scanning to obtain the infrared spectrum of the standard oil sample and the infrared spectrum of the mixed oil sample; Step 4: Use titration method to measure the saponification values ​​of the standard oil sample and the mixed oil sample respectively, and record the saponification values ​​of the standard oil sample and the mixed oil sample; Step 5: Open the infrared spectrum data processing software, preset the band number range on the infrared spectrum data processing software, input the infrared spectra and saponification values ​​of the standard oil sample and the mixed oil sample into the infrared spectrum data processing software in sequence, output the corresponding correlation curve between the band number and the absorbance, and assign a value to the maximum peak height of the absorbance within the band number range, wherein the band number range is set to 1710-1780cm -1 ; Step 6: Use infrared spectrum data processing software to pre-analyze the correlation curves of the standard oil sample and the mixed oil sample, and automatically calculate the correlation coefficient of the corresponding saponification value. If the correlation coefficient of the saponification value of the sample reaches 0.995 or above, it is determined that its correlation curve meets the standard curve requirements and is saved for later use. Otherwise, it is determined that its correlation curve does not meet the standard curve requirements, and returns to step 2 to re-acquire the relevant data of the standard oil sample or the mixed oil sample until there is a standard oil sample and at least four mixed oil samples whose correlation curves all meet the standard curve requirements; Step 7: Take the cold-rolled emulsion used in on-site production, filter the cold-rolled emulsion, and remove dirt in the cold-rolled emulsion; Step 8: adding an organic solvent to the filtered cold-rolled emulsion, and then placing it in a high-speed stirrer and stirring for 5 to 10 minutes at a stirring speed of 8000 rpm to obtain a mixture of the cold-rolled emulsion and the organic solvent, wherein the amount of the organic solvent added is 40 to 100 ml; Step nine: placing the mixture of the cold-rolled emulsion and the organic solvent into a plurality of polypropylene centrifuge tubes, and then centrifuging them on a high-speed centrifuge for 5 to 15 minutes to obtain a mixed centrifugal liquid; Step 10: taking the clear liquid of the upper organic solvent phase from the mixed centrifuged liquid, placing the clear liquid in a rotary evaporator for negative pressure rotary evaporation, and obtaining a rolling oil sample to be tested after the organic solvent and trace water are completely evaporated and removed; Step 11: Take an appropriate amount of rolling oil sample to be tested, put it into a clean sample pool, and use a Fourier transform infrared spectrometer to perform infrared spectrum scanning on the rolling oil sample to be tested. The infrared spectrum scanning of a single sample is repeated multiple times, and a blank scan is performed before each sample scanning to obtain the infrared spectrum of the rolling oil sample to be tested; Step 12: Input the infrared spectrum of the rolling oil sample to be tested into the infrared spectrum data processing software to obtain the correlation curve between the corresponding band number and absorbance. Then, the infrared spectrum data processing software uses a linear interpolation fitting algorithm to pair and fit the correlation curves of the standard oil sample and the mixed oil sample with the correlation curve of the rolling oil sample to be tested, and obtain the saponification value of the rolling oil sample to be tested.

2. The method for rapidly measuring the saponification value of rolling oil in the emulsion for cold rolling production according to claim 1, characterized in that: In the steps 1 and 2, the flow rate of the high-purity nitrogen is controlled to be 30 mL / min.

3. The method for rapidly measuring the saponification value of rolling oil in the emulsion for cold rolling production according to claim 1, characterized in that: In the step 2, the mineral oil is Kunlun L-HM46 hydraulic oil.

4. The method for rapidly measuring the saponification value of rolling oil in the emulsion for cold rolling production according to claim 1, characterized in that: In step three and step eleven, the number of infrared spectrum scans of the single sample is set to 32 times.

5. The method for rapidly measuring the saponification value of rolling oil in the emulsion for cold rolling production according to claim 1, characterized in that: In the step seven, the sampling amount of the cold-rolled emulsion is 400-800 ml, and the concentration of the cold-rolled emulsion is above 1.5%.

6. The method for rapidly measuring the saponification value of rolling oil in the emulsion for cold rolling production according to claim 1, characterized in that: In the step seven, the cold rolled emulsion is filtered by a microporous filter, and the micropore diameter of the filter membrane of the microporous filter is 0.45 μm.

7. The method for rapidly measuring the saponification value of rolling oil in the emulsion for cold rolling production according to claim 1, characterized in that: In the step eight, the organic solvent is one of a mixed solvent of isopropanol and petroleum ether, butanone, and ethylene dichloride, wherein the volume ratio of isopropanol to petroleum ether in the mixed solvent is 1:

2.

8. The method for rapidly measuring the saponification value of rolling oil in the emulsion for cold rolling production according to claim 1, characterized in that: In step nine, the number of the polypropylene centrifuge tubes is 2 to 8, and the volume of the mixed solution in each polypropylene centrifuge tube is controlled to be 15 ml.

9. The method for rapidly measuring the saponification value of rolling oil in the emulsion for cold rolling production according to claim 1, characterized in that: In the step 10, the clear liquid of the upper organic solvent phase is subjected to negative pressure rotary evaporation in a hot water bath at 60-85° C. and a negative pressure of -640 mm Hg.

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