CN114544858A - Method for analyzing and detecting content of uranium in uranium hexafluoride - Google Patents
Method for analyzing and detecting content of uranium in uranium hexafluoride Download PDFInfo
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- CN114544858A CN114544858A CN202111622722.7A CN202111622722A CN114544858A CN 114544858 A CN114544858 A CN 114544858A CN 202111622722 A CN202111622722 A CN 202111622722A CN 114544858 A CN114544858 A CN 114544858A
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Abstract
The invention belongs to the technical field of uranium mining and metallurgy analysis and measurement, and particularly relates to an analysis and detection method for uranium content in uranium hexafluoride. The method mainly comprises the following steps: dividing a uranium hexafluoride sample, adding water for hydrolysis, and dividing hydrolysate; adding an amino sulfonic acid solution to wash the cup wall, directly adding a ferrous sulfate solution, and stirring; placing the beaker in a water bath kettle, and adjusting the temperature of the water bath kettle to 35-45 ℃; adding an oxidant solution along the inner wall of the beaker; continuing stirring, and standing to eliminate bubbles; adding vanadyl sulfate solution; pre-adding a certain volume of potassium dichromate standard solution with the concentration of 1% into a sample solution, inputting the weight of the sample and the volume of the pre-added standard potassium dichromate standard solution into a computer titration software interface, switching to the potassium dichromate standard solution with the concentration of 0.06% after titration is carried out to a stop potential, and automatically calculating the percentage content of uranium in the sample by a computer according to an automatic potentiometric titrator. The method is simple, safe and quick in analysis operation, and is suitable for large-batch sample analysis of enterprises.
Description
Technical Field
The invention belongs to the technical field of uranium mining and metallurgy analysis and measurement, and particularly relates to an analysis and detection method for uranium content in uranium hexafluoride.
Background
Natural uranium hexafluoride is an important raw material for uranium enrichment, and the current domestic method for determining the uranium content in the uranium hexafluoride has national standard GB/T14501.6.1-2008: uranium hexafluoride analysis method section 6 uranium determination. The method comprises the following analysis steps:
hydrolyzing a uranium hexafluoride sample, taking a uranium hexafluoride hydrolysate, reducing uranium (VI) to uranium (IV) by ferrous sulfate in a phosphoric acid medium, oxidizing excessive iron (II) by nitric acid at a proper temperature by using molybdenum (VI) as a catalyst, eliminating nitrogen oxide generated in the oxidation process by sulfamic acid, oxidizing most uranium (IV) by using solid potassium dichromate which is slightly less than stoichiometric in weighing in the presence of vanadyl sulfate, and titrating to an end point by using a potassium dichromate solution.
In the prior art, only one potassium dichromate standard solution with the concentration of 0.8g/L is used for manual titration, the analysis process consumes a long time, the end point control has human errors, the volume calculation of the consumed potassium dichromate solution is complex, and the method is not suitable for large-batch sample analysis.
In view of the above disadvantages in the prior art, there is a need to design an improved method for analyzing and detecting the uranium content in uranium hexafluoride.
Disclosure of Invention
The invention aims to design an analysis and detection method for uranium hexafluoride content, which improves accuracy and precision and realizes uranium hexafluoride content determination of large-batch sample analysis of uranium hexafluoride production enterprises.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a method for determining the content of uranium in uranium hexafluoride comprises the following steps:
(1) the sample tube is cleaned, dried for 2h at the temperature of 110 +/-5 ℃, and cooled to room temperature in a dryer.
(2) The method comprises the following steps of connecting a sample tube with sample dividing equipment, dividing 8-12 g of uranium hexafluoride from a sample container into the sample tube, immersing the sample tube into liquid nitrogen to solidify the uranium hexafluoride, taking the sample tube from the sample dividing equipment after solidification is complete, and immediately putting a gasket, a fastening nut and a plug.
(3) The sample tube with the sample is placed in a desiccator and allowed to stand for more than 3 hours, bringing it to ambient temperature to evaporate the condensed water. The sample tube with the sample is weighed to the nearest 0.1mg and the mass is recorded.
(4) The mass of the cleaned and dried 500mL wide-necked polyethylene bottle was weighed to the nearest 0.1mg and the mass was recorded. The cap should ensure a good seal for the liquid.
(5) 100mL of water was added to the bottle, which was placed in a beaker containing ice and water. The amount of water added is such that the sample tube containing the sample is submerged below the surface of the liquid.
(6) A line is tied on a sample tube filled with a sample, and the sample tube is immersed into liquid nitrogen to completely immerse the sample tube and is kept for 10 min.
(7) And taking out the sample tube from the liquid nitrogen, releasing the line, immediately removing the plug and the nut, putting the gasket and the sample tube into a polyethylene bottle, keeping the opening of the sample tube immersed under the water, covering the bottle cap and screwing the bottle cap.
(8) The polyethylene bottle is taken out of the ice water and placed in a ventilation cabinet, the sample tube is kept submerged in the water all the time, so that the sample is slowly hydrolyzed, and the bottle is carefully shaken when necessary, so that the hydrolysis is facilitated.
(9) When the hydrolysis was complete, the sample tube and gasket were removed with forceps, rinsed with water, and the rinse was poured into a bottle. Dry the outside of the bottle, screw the cap, weigh the bottle and solution to 0.1mg, record the mass. Shaking up.
(10) Washing the sample tube, the gasket, the plug and the nut with water, then washing with alcohol, drying at 110 +/-5 ℃ for 2h, installing a set, drying for 0.5h, weighing the mass after cooling, and recording the mass to be accurate to 0.1 mg.
(11) Weighing a uranium hexafluoride hydrolysis solution containing 0.5-0.6 g of uranium as a sample, accurately measuring the sample to 0.1mg, and recording the mass; the sample was transferred to a 400mL fluorine-resistant beaker, 30mL concentrated phosphoric acid was added, and the mixture was stirred well.
(12) While stirring, 5mL of a saturated solution of sulfamic acid was added. 8mL of the ferrous sulfate solution was added to the sample solution by a pipette so as not to flow down the wall of the beaker. The stirring is continued at room temperature for reduction for not less than 1 min.
(13) Adding 5mL of sulfuric acid, adjusting the temperature of the solution to 35-40 ℃, adding 8mL of oxidant along the wall by using a pipette, stirring for 2-3 min, and then placing for 0.5 min. After the addition of the oxidizing agent, the test solution turns dark brown, which should disappear within 30 s.
(14) Under stirring, 90mL of water, 10mL of vanadyl sulfate solution were added along the wall. Titration was completed within 5min after addition of vanadyl sulfate solution.
(15) Starting clicking, pre-adding a potassium dichromate standard solution with the concentration of 1% by a automatic potentiometric titrator into 12.00mL, stirring for 1min, then starting titration by using the potassium dichromate standard solution with the concentration of 1%, automatically switching to a dilute potassium dichromate standard solution with the concentration of 0.06% for titration when the termination potential value is-490 mV, drawing a titration curve in real time by a computer, and carrying out data processing of a first derivative on the titration curve to obtain the titration end potential. The click begins and the instrument automatically starts titration with a standard solution of potassium dichromate. Titration was complete within 7 minutes.
(16) The percentage content of uranium in the sample is automatically calculated by a computer according to a result calculation formula established by automatic potentiometric titrator software by input sample weighing, the volume of the pre-added standard potassium dichromate solution, the volume of the consumed two standard potassium dichromate solutions and an end point potential.
The beneficial effects obtained by the invention are as follows:
the standard deviation of repeatability of the uranium hexafluoride sample analysis is less than or equal to 0.03 percent and is superior to the standard deviation of repeatability of 0.042 percent of the national standard method. Compared with the national standard method, the method has no significant difference, and has high precision and accuracy. The analysis operation of the invention is simpler and faster than the national standard method, the automatic operation of the instrument can be realized, a skilled analyst can perform 3 times of parallel titration analysis in 20min, and the invention is suitable for large-batch sample analysis of enterprises. The analysis efficiency is greatly improved by using the analysis method of the invention.
Detailed Description
The method mainly comprises the following steps: dividing a uranium hexafluoride sample, adding water for hydrolysis, and dividing hydrolysate; adding an amino sulfonic acid solution to wash the cup wall, directly adding a ferrous sulfate solution, and stirring; placing the beaker in a water bath kettle, and adjusting the temperature of the water bath kettle to 35-45 ℃; adding an oxidant solution along the inner wall of the beaker; continuing stirring, and standing to eliminate bubbles; adding vanadyl sulfate solution; pre-adding a certain volume of potassium dichromate standard solution with the concentration of 1% into a sample solution, inputting the weight of the sample and the volume of the pre-added standard potassium dichromate standard solution into a computer titration software interface, switching to the potassium dichromate standard solution with the concentration of 0.06% after titration is carried out to a stop potential, and automatically calculating the percentage content of uranium in the sample by a computer according to an automatic potentiometric titrator.
Example one
Analyzing a No. 1 uranium hexafluoride sample, making 6 parallel samples, and calculating the relative standard deviation RSD of the precision of the method.
The specific analysis steps are as follows:
(1) the sample tube is cleaned, dried for 2h at the temperature of 110 +/-5 ℃, and cooled to room temperature in a dryer.
(2) The method comprises the following steps of connecting a sample tube with sample dividing equipment, dividing 8-12 g of uranium hexafluoride from a sample container into the sample tube, immersing the sample tube into liquid nitrogen to solidify the uranium hexafluoride, taking the sample tube from the sample dividing equipment after solidification is complete, and immediately putting a gasket, a fastening nut and a plug.
(3) The sample tube with the sample is placed in a desiccator and allowed to stand for more than 3 hours, bringing it to ambient temperature to evaporate the condensed water. The sample tube containing the sample was weighed to the nearest 0.1mg and the mass recorded.
(4) The mass of the cleaned and dried 500mL wide-necked polyethylene bottle was weighed to the nearest 0.1mg and the mass was recorded. The cap should ensure a good seal for the liquid.
(5) 100mL of water was added to the bottle, which was placed in a beaker containing ice and water. The amount of water added is such that the sample tube containing the sample is submerged below the surface of the liquid.
(6) A line is tied on a sample tube filled with a sample, and the sample tube is immersed into liquid nitrogen to completely immerse the sample tube and is kept for 10 min.
(7) And taking out the sample tube from the liquid nitrogen, releasing the line, immediately removing the plug and the nut, putting the gasket and the sample tube into a polyethylene bottle, keeping the opening of the sample tube immersed under the water, covering the bottle cap and screwing the bottle cap.
(8) The polyethylene bottle is taken out of the ice water and placed in a ventilation cabinet, the sample tube is kept submerged in the water all the time, so that the sample is slowly hydrolyzed, and the bottle is carefully shaken when necessary, so that the hydrolysis is facilitated.
(9) When the hydrolysis was complete, the sample tube and gasket were removed with forceps, rinsed with water, and the rinse was poured into a bottle. Dry the outside of the bottle, screw the cap, weigh the bottle and solution to 0.1mg, record the mass. Shaking up.
(10) Washing the sample tube, the gasket, the plug and the nut with water, then washing with alcohol, drying at 110 +/-5 ℃ for 2h, installing a set, drying for 0.5h, weighing the mass after cooling, and recording the mass to be accurate to 0.1 mg.
(11) Weighing 6 parts of uranium hexafluoride hydrolysis solution containing 0.5-0.6 g of uranium, accurately measuring the amount of the uranium hexafluoride hydrolysis solution to 0.1mg, and recording the mass; the sample was transferred to a 400mL fluorine-resistant beaker, and 30mL concentrated phosphoric acid was added to each beaker and stirred well.
(12) With stirring, 5mL of saturated solution of sulfamic acid was added. 8mL of the ferrous sulfate solution was added to the sample solution by a pipette so as not to flow down the wall of the beaker. The stirring is continued at room temperature for reduction for not less than 1 min.
(13) Adding 5mL of sulfuric acid, adjusting the temperature of the solution to 35-40 ℃, adding 8mL of oxidant along the wall by using a pipette, stirring for 2-3 min, and then placing for 0.5 min. After the addition of the oxidizing agent, the test solution becomes brownish black, which should disappear within 30 s.
(14) Under stirring, 90mL of water, 10mL of vanadyl sulfate solution were added along the wall. Titration was completed within 5min after addition of vanadyl sulfate solution.
(15) Starting clicking, pre-adding a potassium dichromate standard solution with the concentration of 1% into the instrument by 12.00mL, stirring for 1min, then starting titration by using the potassium dichromate standard solution with the concentration of 1%, automatically switching to a dilute potassium dichromate standard solution with the concentration of 0.06% for titration when the termination potential value is-490 mV, drawing a titration curve in real time by a computer, and carrying out data processing of a first derivative on the titration curve to obtain the titration end potential. The click begins and the instrument automatically starts titration with a standard solution of potassium dichromate. Titration was complete within 7 minutes.
(16) The percentage content of uranium in the sample is automatically calculated by a computer according to a result calculation formula established by automatic potentiometric titrator software by input sample weighing, the volume of the pre-added standard potassium dichromate solution, the volume of the consumed two standard potassium dichromate solutions and an end point potential.
The results of parallel titration of uranium hexafluoride samples are shown in table 1:
TABLE 1 precision experimental results table for uranium hexafluoride
The relative standard deviation of the results of the 6 parallels is 0.036%, and the requirements of sample analysis and detection are met.
Example two
From the same uranium hexafluoride sample, A, B two persons each take 6 replicates and perform an indoor repetitive experiment according to the same procedure.
The specific analysis steps are as follows:
(1) the sample tube is cleaned, dried for 2h at the temperature of 110 +/-5 ℃, and cooled to room temperature in a dryer.
(2) The method comprises the following steps of connecting a sample tube with sample dividing equipment, dividing 8-12 g of uranium hexafluoride from a sample container into the sample tube, immersing the sample tube into liquid nitrogen to solidify the uranium hexafluoride, taking the sample tube from the sample dividing equipment after solidification is complete, and immediately putting a gasket, a fastening nut and a plug.
(3) The sample tube with the sample is placed in a desiccator and allowed to stand for more than 3 hours, bringing it to ambient temperature to evaporate the condensed water. The sample tube with the sample is weighed to the nearest 0.1mg and the mass is recorded.
(4) The mass of the cleaned and dried 500mL wide-necked polyethylene bottle was weighed to the nearest 0.1mg and the mass was recorded. The cap should ensure a good seal for the liquid.
(5) 100mL of water was added to the bottle, which was placed in a beaker containing ice and water. The amount of water added is such that the sample tube containing the sample is submerged below the surface of the liquid.
(6) A line is tied on a sample tube filled with a sample, and the sample tube is immersed into liquid nitrogen to completely immerse the sample tube and is kept for 10 min.
(7) Taking out the sample tube from the liquid nitrogen, releasing the line, immediately removing the plug and the nut, putting the gasket and the sample tube into a polyethylene bottle, keeping the opening of the sample tube immersed under the water, covering the bottle cover and screwing.
(8) The polyethylene bottle is taken out of the ice water and placed in a ventilation cabinet, the sample tube is kept submerged in the water all the time, so that the sample is slowly hydrolyzed, and the bottle is carefully shaken when necessary, so that the hydrolysis is facilitated.
(9) When the hydrolysis was complete, the sample tube and gasket were removed with forceps, rinsed with water, and the rinse was poured into a bottle. Dry the outside of the bottle, screw the cap, weigh the bottle and solution to 0.1mg, record the mass. Shaking up.
(10) Washing the sample tube, the gasket, the plug and the nut with water, then washing with alcohol, drying at 110 +/-5 ℃ for 2h, installing a set, drying for 0.5h, weighing the mass after cooling, and recording the mass to be accurate to 0.1 mg.
(11) Weighing 6 parts of uranium hexafluoride hydrolysis solution containing 0.5-0.6 g of uranium by two persons respectively, accurately measuring the solution to 0.1mg, and recording the mass; the sample was transferred to a 400mL fluorine-resistant beaker, and 30mL concentrated phosphoric acid was added to each beaker and stirred well.
(12) While stirring, 5mL of a saturated solution of sulfamic acid was added. 8mL of the ferrous sulfate solution was added to the sample solution by a pipette so as not to flow down the wall of the beaker. The stirring is continued at room temperature for reduction for not less than 1 min.
(13) Adding 5mL of sulfuric acid, adjusting the temperature of the solution to 35-40 ℃, adding 8mL of oxidant along the wall by using a pipette, stirring for 2-3 min, and then placing for 0.5 min. After the addition of the oxidizing agent, the test solution turns dark brown, which should disappear within 30 s.
(14) Under stirring, 90mL of water, 10mL of vanadyl sulfate solution were added along the wall. Titration was completed within 5min after addition of vanadyl sulfate solution.
(15) Starting clicking, pre-adding a potassium dichromate standard solution with the concentration of 1% into the instrument by 12.00mL, stirring for 1min, then starting titration by using the potassium dichromate standard solution with the concentration of 1%, automatically switching to a dilute potassium dichromate standard solution with the concentration of 0.06% for titration when the termination potential value is-490 mV, drawing a titration curve in real time by a computer, and carrying out data processing of a first derivative on the titration curve to obtain the titration end potential. The click begins and the instrument automatically starts titration with a standard solution of potassium dichromate. Titration was complete within 7 minutes.
(16) The percentage content of uranium in the sample is automatically calculated by a computer according to a result calculation formula established by automatic potentiometric titrator software by input sample weighing, the volume of the pre-added standard potassium dichromate solution, the volume of the consumed two standard potassium dichromate solutions and an end point potential.
The analysis result data are shown in Table 2.
TABLE 2 repeatability tests
From the data in table 2, it is known that the A, B analysis results of two persons are consistent, the repeatability is good, and is superior to the indoor repeatability of 0.042% required by the national standard.
EXAMPLE III
The method is similar to the national standard GB/T14501.6.1-2008: uranium hexafluoride analysis method part 6: uranium determination methods were compared and 6 replicates were taken from each of the same persons.
The specific analysis steps are as follows:
(1) the sample tube is cleaned, dried for 2h at the temperature of 110 +/-5 ℃, and cooled to room temperature in a dryer.
(2) The method comprises the following steps of connecting a sample tube with sample dividing equipment, dividing 8-12 g of uranium hexafluoride from a sample container into the sample tube, immersing the sample tube into liquid nitrogen to solidify the uranium hexafluoride, taking the sample tube from the sample dividing equipment after solidification is complete, and immediately putting a gasket, a fastening nut and a plug.
(3) The sample tube with the sample is placed in a desiccator and allowed to stand for more than 3 hours, bringing it to ambient temperature to evaporate the condensed water. The sample tube with the sample is weighed to the nearest 0.1mg and the mass is recorded.
(4) The mass of the cleaned and dried 500mL wide-necked polyethylene bottle was weighed to the nearest 0.1mg and the mass was recorded. The cap should ensure a good seal for the liquid.
(5) 100mL of water was added to the bottle, which was placed in a beaker containing ice and water. The amount of water added is such that the sample tube containing the sample is submerged below the surface of the liquid.
(6) A line is tied on a sample tube filled with a sample, and the sample tube is immersed into liquid nitrogen to completely immerse the sample tube and is kept for 10 min.
(7) And taking out the sample tube from the liquid nitrogen, releasing the line, immediately removing the plug and the nut, putting the gasket and the sample tube into a polyethylene bottle, keeping the opening of the sample tube immersed under the water, covering the bottle cap and screwing the bottle cap.
(8) The polyethylene bottle is taken out of the ice water and placed in a ventilation cabinet, the sample tube is kept submerged in the water all the time, so that the sample is slowly hydrolyzed, and the bottle is carefully shaken when necessary, so that the hydrolysis is facilitated.
(9) When the hydrolysis was complete, the sample tube and gasket were removed with forceps, rinsed with water, and the rinse was poured into a bottle. Dry the outside of the bottle, screw the cap, weigh the bottle and solution to 0.1mg, record the mass. Shaking up.
(10) Washing the sample tube, the gasket, the plug and the nut with water, then washing with alcohol, drying at 110 +/-5 ℃ for 2h, installing a set, drying for 0.5h, weighing the mass after cooling, and recording the mass to be accurate to 0.1 mg.
(11) Weighing 6 parts of uranium hexafluoride hydrolysis solution containing 0.5-0.6 g of uranium, accurately measuring the amount of the uranium hexafluoride hydrolysis solution to 0.1mg, and recording the mass; the sample was transferred to a 400mL fluorine-resistant beaker, and 30mL concentrated phosphoric acid was added to each beaker and stirred well.
(12) While stirring, 5mL of a saturated solution of sulfamic acid was added. 8mL of the ferrous sulfate solution was added to the sample solution by a pipette so as not to flow down the wall of the beaker. The stirring is continued at room temperature for reduction of not less than 1 min.
(13) Adding 5mL of sulfuric acid, adjusting the temperature of the solution to 35-40 ℃, adding 8mL of oxidant along the wall by using a pipette, stirring for 2-3 min, and then placing for 0.5 min. After the addition of the oxidizing agent, the test solution turns dark brown, which should disappear within 30 s.
(14) Under stirring, 90mL of water, 10mL of vanadyl sulfate solution were added along the wall. Titration was completed within 5min after addition of vanadyl sulfate solution.
(15) Starting clicking, pre-adding a potassium dichromate standard solution with the concentration of 1% into the instrument by 12.00mL, stirring for 1min, then starting titration by using the potassium dichromate standard solution with the concentration of 1%, automatically switching to a dilute potassium dichromate standard solution with the concentration of 0.06% for titration when the termination potential value is-490 mV, drawing a titration curve in real time by a computer, and carrying out data processing of a first derivative on the titration curve to obtain the titration end potential. The click begins and the instrument automatically starts titration with a standard solution of potassium dichromate. Titration was complete within 7 minutes.
(16) The percentage content of uranium in the sample is automatically calculated by a computer according to a result calculation formula established by automatic potentiometric titrator software by input sample weighing, the volume of the pre-added standard potassium dichromate solution, the volume of the consumed two standard potassium dichromate solutions and an end point potential.
Meanwhile, the national standard GB/T14501.6.1-2008 is used: uranium hexafluoride analysis method part 6: uranium determination methods the same uranium hexafluoride samples were analyzed and the data are given below, see table 3.
TABLE 3 comparison analysis experiment table of the method of the present invention and the national standard method
The relative standard deviation of the invention is less than or equal to 0.036 percent and is superior to the relative standard deviation of 0.055 percent of the national standard method.
Claims (9)
1. A method for analyzing and detecting the content of uranium in uranium hexafluoride is characterized by comprising the following steps: the method comprises the following steps:
(1) cleaning the sample tube, drying for 2h at the temperature of 110 +/-5 ℃, and cooling to room temperature in a dryer;
(2) connecting the sample tube with sample dividing equipment, dividing 8-12 g of uranium hexafluoride from a sample container into the sample tube, immersing the sample tube into liquid nitrogen to solidify the uranium hexafluoride, taking the sample tube from the sample dividing equipment after the uranium hexafluoride is completely solidified, immediately placing a gasket, a fastening nut and a plug;
(3) placing the sample tube with the sample in a dryer and standing for more than 3h to make the sample tube reach the temperature of the surrounding environment so as to evaporate condensed water; weighing the mass of the sample tube filled with the sample to be accurate to 0.1mg, and recording the mass;
(4) weighing the mass of a cleaned and dried 500mL wide-mouth polyethylene bottle to be accurate to 0.1mg, and recording the mass; the bottle cap should ensure good sealing of the liquid;
(5) adding 100mL of water to the bottle, and placing the bottle in a beaker containing ice and water; the amount of water added is such that the sample tube containing the sample is submerged below the liquid level;
(6) tying a line on a sample tube filled with a sample, immersing the sample tube into liquid nitrogen to completely immerse the sample tube, and keeping for 10 min;
(7) taking out the sample tube from the liquid nitrogen, releasing the line, immediately removing the plug and the nut, putting the gasket and the sample tube into a polyethylene bottle, keeping the opening of the sample tube immersed in water, covering a bottle cap and screwing;
(8) taking the polyethylene bottle out of the ice water and placing the polyethylene bottle in a ventilation cabinet, and keeping the sample tube submerged in the water all the time to slowly hydrolyze the sample;
(9) after complete hydrolysis, taking out the sample tube and the gasket by using tweezers, washing by using water, and merging the washing liquid into a bottle; wiping the outside of the bottle, screwing the bottle cap, weighing the bottle and the solution until the mass is accurate to 0.1mg, recording the mass, and shaking up;
(10) washing the sample tube, the gasket, the plug and the nut with water, then washing with alcohol, drying at 110 +/-5 ℃ for 2h, installing a set of the sample tube, the plug and the nut, drying for 0.5h, weighing the mass of the sample tube after cooling, and accurately measuring the mass to 0.1mg, and recording the mass;
(11) weighing a uranium hexafluoride hydrolysis solution containing 0.5-0.6 g of uranium as a sample, accurately measuring the sample to 0.1mg, and recording the mass; transferring the sample to a 400mL fluorine-resistant beaker, adding concentrated phosphoric acid, and uniformly stirring;
(12) under the condition of stirring, 5mL of sulfamic acid saturated solution is added; adding 8mL of ferrous sulfate solution into the sample solution by a pipette, wherein the ferrous sulfate solution cannot flow down along the wall of the beaker; continuously stirring at room temperature for reduction for no less than 1 min;
(13) adding 5mL of sulfuric acid, adjusting the temperature of the solution, adding 8mL of oxidant along the wall by using a pipette, stirring for 2-3 min, and then placing for 0.5 min; after the oxidant is added, the test solution becomes brownish black, and the color disappears in 30 s;
(14) adding water and vanadyl sulfate solution along the wall under the condition of stirring; completing titration within 5min after adding vanadyl sulfate solution;
(15) the automatic potentiometric titrator equipped with platinum rod electrodes was turned on and the method parameters were entered from the computer software: the reaction direction is set as negative; minimum latency 0 s; a maximum waiting time of 50 s; the liquid adding speed is 5.00 mL/min; signal drift 4; the minimum liquid adding volume is 10.00 mu L; stop volume 50.00 mL; the potential evaluation value was 35 mV; the volume after the equivalence point is 1 mL; stopping measuring the potential to-700 mV; inputting the weight of a sample, and inputting a pre-concentration potassium dichromate standard solution with the volume of 12.00mL, wherein the pre-concentration of the potassium dichromate standard solution is 1%;
(16) starting clicking, pre-adding a potassium dichromate standard solution with the concentration of 1% by the instrument by 12.00mL, stirring for 1min, then starting titration by using the potassium dichromate standard solution, automatically switching to a dilute potassium dichromate standard solution with the concentration of 0.06% for titration when the termination potential value is-490 mV, drawing a titration curve in real time by using a computer, carrying out data processing of a first derivative on the titration curve, and automatically searching the titration end point potential by the instrument;
the formula is as follows:
wherein:
the electrode measures the electromotive force of the working cell
Δ V- -volume of addition of Standard titration solution
The click is started, and the instrument automatically starts to titrate by using a potassium dichromate standard solution; titration is completed within 7 minutes;
(17) the percentage content of uranium in the sample is automatically calculated by a computer according to a result calculation formula established by automatic potentiometric titrator software by input sample weighing, the volume of the pre-added standard potassium dichromate solution and the volume of the consumed two standard potassium dichromate solutions; the formula is as follows:
ωUF6 purity-purity of uranium hexafluoride,%;
242.73- -conversion factor of potassium dichromate to uranium;
1.479- -conversion factor of uranium hexafluoride to uranium;
V1-the volume of the concentrated potassium dichromate standard solution added, mL;
V2-volume, mL, of diluted potassium dichromate standard solution added at the end point;
ρ1-density of standard solution of concentrated potassium dichromate, g/mL;
ρ2-density of diluted potassium dichromate standard solution, g/mL;
C1-percentage concentration of concentrated potassium dichromate standard solution,%;
C2-percent concentration of dilute potassium dichromate standard solution;
mtest specimen- -mass of sample, g.
2. The method for analyzing and detecting the uranium content in uranium hexafluoride according to claim 1, wherein: the amount of the concentrated phosphoric acid added in the step (11) is 15 ml.
3. The method for analyzing and detecting the uranium content in uranium hexafluoride according to claim 2, wherein: and (3) adjusting the temperature of the solution to 35-40 ℃.
4. The method for analyzing and detecting the uranium content in uranium hexafluoride according to claim 3, wherein: 90mL of water and 10mL of vanadyl sulfate solution are added in the step (14).
5. The method for analyzing and detecting the uranium content in uranium hexafluoride according to claim 4, wherein: in the step (15), the stirring speed is 8 r/min.
6. The method for analyzing and detecting the uranium content in uranium hexafluoride according to claim 5, wherein: in the step (15), the mass percent concentration of the concentrated potassium dichromate standard solution is 1%, and the mass percent concentration of the dilute potassium dichromate standard solution is 0.06%.
7. The method for analyzing and detecting the uranium content in uranium hexafluoride according to claim 6, wherein: and (5) pre-adding 12.00mL of 1% potassium dichromate standard solution by using an instrument in the step (15), and stirring for 1 min.
8. The method for analyzing and detecting the uranium content in uranium hexafluoride according to claim 7, wherein: in the step (15), the titration is started by using a potassium dichromate standard solution with the concentration of 1%, and when the titration is carried out until the stopping potential value is-490 mV, the titration is switched to a dilute potassium dichromate standard solution with the concentration of 0.06% for titration to an equivalent point.
9. The method for analyzing and detecting the uranium content in uranium hexafluoride of claim 8, wherein: in the step (16), titration is started by using a potassium dichromate standard solution with the concentration of 1%.
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