CN111141730B - Method for measuring iron content in gadolinium-iron alloy - Google Patents
Method for measuring iron content in gadolinium-iron alloy Download PDFInfo
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Abstract
The invention discloses a method for measuring the iron content in gadolinium-iron alloy, which comprises the steps of slowly dissolving a gadolinium-iron sample by hydrochloric acid, fixing the volume, then sampling, sequentially adding sulfur-phosphorus mixed acid and diphenylamine sodium sulfonate indicator, fixing the sample to be purple by using a potassium dichromate standard solution, namely, obtaining the end point, and calculating the iron content in the gadolinium-iron alloy according to the volume of the used potassium dichromate standard solution. The method can timely and accurately determine the iron content in the gadolinium-iron alloy, improves the analysis and detection efficiency, and can save two thirds of time and two thirds of medicine consumption compared with the existing determination method.
Description
Technical Field
The invention belongs to the technical field of analytical chemistry, and particularly relates to a method for measuring the iron content in gadolinium ferroalloy.
Background
Gadolinium ferroalloy is mainly used as an additive of a rubidium iron boron permanent magnet, a giant magnetostrictive alloy is manufactured, a photomagnetic recording material, a nuclear fuel diluent and the like, when the gadolinium ferroalloy is used as the additive of the rubidium iron boron permanent magnet, the content of gadolinium, iron and impurities in the gadolinium ferroalloy directly influences the performance of the rubidium iron boron permanent magnet, so the content measurement of each component in the gadolinium ferroalloy has very important significance, iron is used as a main component in the gadolinium ferroalloy, how to rapidly and accurately measure the iron content in the gadolinium ferroalloy, which is beneficial to the gadolinium ferroalloy production process, the production condition of the gadolinium ferroalloy is timely and accurately reflected, operators can conveniently adjust process conditions, and the quality of ferrochrome products is improved. However, the method for measuring the iron content in the neodymium iron boron alloy is commonly adopted at present, wherein the method is mainly used for measuring the iron content in the gadolinium iron alloy by using potassium dichromate for titration, the method has complicated operation steps, sodium tungstate is required to be used as an indicator, titanium trichloride is used for reducing the sodium tungstate into ferrous iron, potassium dichromate solution is dripped for oxidizing excessive trivalent titanium, then mixed sulfuric-phosphoric acid and sodium diphenylamine sulfonate indicator are added, and the potassium dichromate standard solution is used for titrating the iron content in the gadolinium iron alloy, so that the measuring time is long, and analysis operators are easy to operate by mistake or consider that the error is increased.
Disclosure of Invention
Aiming at the defects, the invention discloses a method for measuring the iron content in the gadolinium ferroalloy, which can timely and accurately measure the iron content in the gadolinium ferroalloy and improve the analysis and detection efficiency.
The invention is realized by adopting the following technical scheme:
a method for measuring the iron content in gadolinium-iron alloy comprises the following steps:
(1) weighing 2g of gadolinium-iron sample into a 100ml volumetric flask, slowly adding 10ml of hydrochloric acid to dissolve the gadolinium-iron sample, controlling the temperature at 35-40 ℃ in the dissolving process, and after complete dissolution, fixing the volume to a scale with distilled water to obtain a solution A; taking 10ml of hydrochloric acid into a 100ml volumetric flask, and then using distilled water to fix the volume to a scale to obtain a solution B;
(2) taking 20ml of the solution A obtained in the step (1) to a triangular flask of 250ml, then adding 10ml of mixed sulfuric-phosphoric acid, then dropwise adding 3-4 drops of sodium diphenylamine sulfonate indicator, titrating with a potassium dichromate standard solution with the concentration of 0.006mol/l until the solution becomes purple, namely, a terminal point, and reading the volume V of the used potassium dichromate standard solution 1 (ii) a Taking 20ml of the solution B obtained in the step (1) to a 250ml triangular flask, then adding 10ml of mixed sulfur and phosphorus acid, then dropwise adding 3-4 drops of sodium diphenylamine sulfonate indicator, titrating with a potassium dichromate standard solution with the concentration of 0.006mol/l until the solution becomes purple, namely, an end point, and reading the volume V of the used potassium dichromate standard solution 0 ；
(3) Calculating the mass fraction of the iron in the gadolinium-iron sample according to the formula (1), wherein the unit is percent, and the formula (1) is as follows:
Further, the volume fraction of the hydrochloric acid is 50%.
Further, the sodium diphenylamine sulfonate indicator in the step (2) is prepared by dissolving 0.5g of sodium diphenylamine sulfonate in 100ml of distilled water.
Further, the granularity of the gadolinium-iron sample is less than 2mm, and the gadolinium-iron sample is obtained by manually polishing the surface layer to obtain the gadolinium-iron sample with smooth surface and good metal luster. The size of less than 2mm is selected to shorten the sample dissolving time as much as possible in the measuring sensitivity range and improve the measuring efficiency; samples with fresh fracture surfaces and good metallic luster were selected for analysis in order to avoid introducing electrolyte impurities or alloy scale, which would lower the analysis results.
Compared with the prior art, the technical scheme has the following beneficial effects:
1. the method of the invention directly adopts hydrochloric acid to dissolve a gadolinium iron sample, then adds sulfur-phosphorus mixed acid and diphenylamine sodium sulfonate indicator, and directly titrates to the end point by using a potassium dichromate standard solution. Compared with the original method for determining the iron content in the neodymium iron boron alloy, sodium tungstate is not used, titanium trichloride is not used to reduce the iron into ferrous iron, excessive ferric titanium is oxidized by dripping potassium dichromate solution, because the gadolinium ferroalloy is in the acid dissolution process, only a small amount of ferric fluoride and ferric oxide in a sample are dissolved to bring ferric iron ions into a dissolution solution, the gadolinium ferroalloy contains a large amount of metallic iron, under the existence of a large amount of metallic iron, the gadolinium ferroalloy can perform redox reaction with the ferric iron in the solution to form ferrous iron ions, so that the existence of the ferric iron ions in the solution can be reduced, titanium trioxide is not needed to reduce the ferrous iron, and excessive ferric titanium is oxidized by dripping potassium dichromate solution, the determination step is simplified, the determination time is shortened, the consumption of determination medicines is reduced, and the determination analysis efficiency is improved.
2. When the gadolinium iron sample is dissolved by hydrochloric acid, the hydrochloric acid is slowly added for dissolution, and the temperature in the dissolution process is controlled at the same time, because the dissolution reaction is too fast and the temperature is increased easily due to too fast acid addition speed, the excessive temperature can promote the divalent iron ions to be quickly oxidized into the trivalent iron ions in the air, and the trivalent iron ions cannot be measured by using the potassium dichromate standard solution and the sodium diphenylamine sulfonate indicator, so that the measurement deviation occurs, the sample dissolution temperature is strictly controlled, the sample is prevented from being oxidized into the trivalent iron ions, and the measurement and analysis accuracy is improved.
3. The method has the advantages of simple operation, less consumption of measured medicines, greatly shortened measurement time, contribution to timely and accurately reflecting the production condition of the gadolinium ferroalloy in the production process of the gadolinium ferroalloy, convenience for operators to timely adjust process conditions and improvement on the quality of ferrochrome alloy products.
Detailed Description
The invention is further illustrated by the following examples, which are not to be construed as limiting the invention thereto. The conditions and methods of the gadolinium iron are specified in the following examples, and the technical means employed are generally conventional means well known to those skilled in the art.
Example 1:
a method for measuring the iron content in gadolinium-iron alloy is characterized by comprising the following steps: the method comprises the following steps:
(1) weighing 2g of the gadolinium-iron sample into a 100ml volumetric flask, slowly adding 10ml of hydrochloric acid with the volume fraction of 50% to dissolve the gadolinium-iron sample, controlling the temperature at 38 ℃ in the dissolving process, and after complete dissolution, fixing the volume to a scale with distilled water to obtain a solution A; taking 10ml of hydrochloric acid into a 100ml volumetric flask, and then using distilled water to fix the volume to a scale to obtain a solution B; the granularity of the gadolinium-iron sample is less than 2mm, and the gadolinium-iron sample is obtained by manually polishing the surface layer to obtain a gadolinium-iron sample with smooth surface and good metal luster;
(2) taking 20ml of the solution A obtained in the step (1) to a 250ml triangular flask, then adding 10ml of mixed sulfur and phosphorus acid, then dropwise adding 3-4 drops of sodium diphenylamine sulfonate indicator, titrating with a potassium dichromate standard solution with the concentration of 0.006mol/l until the solution becomes purple, namely, an end point, and reading the volume V of the used potassium dichromate standard solution 1 (ii) a Taking 20ml of the solution B obtained in the step (1) to a 250ml triangular flask, then adding 10ml of mixed sulfur and phosphorus acid, then dropwise adding 3-4 drops of sodium diphenylamine sulfonate indicator, titrating with a potassium dichromate standard solution with the concentration of 0.006mol/l until the solution becomes purple, namely, an end point, and reading the volume V of the used potassium dichromate standard solution 0 (ii) a The sodium diphenylamine sulfonate indicator is prepared by dissolving 0.5g of sodium diphenylamine sulfonate in 100ml of distilled water;
(3) calculating the mass fraction of iron in the gadolinium iron sample according to the formula (1), wherein the formula (1) is as follows:
Example 2:
a method for measuring the iron content in gadolinium-iron alloy is characterized by comprising the following steps: the method comprises the following steps:
(1) weighing 2g of gadolinium-iron sample into a 100ml volumetric flask, slowly adding 10ml of hydrochloric acid with 50 percent of volume fraction to dissolve the gadolinium-iron sample, controlling the temperature at 35 ℃ in the dissolving process, and after complete dissolution, fixing the volume to a scale with distilled water to obtain a solution A; taking 10ml of hydrochloric acid into a 100ml volumetric flask, and then adding distilled water to a constant volume to a scale to obtain a solution B; the granularity of the gadolinium iron sample is less than 2mm, and the gadolinium iron sample is obtained by manually polishing a surface layer to have a smooth surface and good metal luster;
(2) taking 20ml of the solution A obtained in the step (1) to a 250ml triangular flask, then adding 10ml of mixed sulfur and phosphorus acid, then dropwise adding 3-4 drops of sodium diphenylamine sulfonate indicator, titrating with a potassium dichromate standard solution with the concentration of 0.006mol/l until the solution becomes purple, namely, an end point, and reading the volume V of the used potassium dichromate standard solution 1 (ii) a Taking 20ml of the solution B obtained in the step (1) to a triangular flask of 250ml, then adding 10ml of mixed sulfuric-phosphoric acid, then dropwise adding 3-4 drops of sodium diphenylamine sulfonate indicator, titrating with a potassium dichromate standard solution with the concentration of 0.006mol/l until the solution becomes purple, namely, a terminal point, and reading the volume V of the used potassium dichromate standard solution 0 (ii) a The sodium diphenylamine sulfonate indicator is prepared by dissolving 0.5g of sodium diphenylamine sulfonate in every 100ml of distilled water;
(3) calculating the mass fraction of iron in the gadolinium iron sample according to the formula (1), wherein the formula (1) is as follows:
Example 3:
a method for measuring the iron content in gadolinium-iron alloy is characterized by comprising the following steps: the method comprises the following steps:
(1) weighing 2g of the gadolinium-iron sample into a 100ml volumetric flask, slowly adding 10ml of hydrochloric acid with the volume fraction of 50% to dissolve the gadolinium-iron sample, controlling the temperature at 40 ℃ in the dissolving process, and after complete dissolution, fixing the volume to a scale with distilled water to obtain a solution A; taking 10ml of hydrochloric acid into a 100ml volumetric flask, and then adding distilled water to a constant volume to a scale to obtain a solution B; the granularity of the gadolinium-iron sample is less than 2mm, and the gadolinium-iron sample is obtained by manually polishing the surface layer to obtain a gadolinium-iron sample with smooth surface and good metal luster;
(2) taking 20ml of the solution A obtained in the step (1) to a 250ml triangular flask, then adding 10ml of mixed sulfur and phosphorus acid, then dropwise adding 3-4 drops of sodium diphenylamine sulfonate indicator, titrating with a potassium dichromate standard solution with the concentration of 0.006mol/l until the solution becomes purple, namely, an end point, and reading the volume V of the used potassium dichromate standard solution 1 (ii) a Taking 20ml of the solution B obtained in the step (1) to a triangular flask of 250ml, then adding 10ml of mixed sulfuric-phosphoric acid, then dropwise adding 3-4 drops of sodium diphenylamine sulfonate indicator, titrating with a potassium dichromate standard solution with the concentration of 0.006mol/l until the solution becomes purple, namely, a terminal point, and reading the volume V of the used potassium dichromate standard solution 0 (ii) a The sodium diphenylamine sulfonate indicator is prepared by dissolving 0.5g of sodium diphenylamine sulfonate in every 100ml of distilled water;
(3) calculating the mass fraction of the iron in the gadolinium-iron sample according to the formula (1), wherein the unit is percent, and the formula (1) is as follows:
Example 4:
a method for measuring the iron content in gadolinium-iron alloy is characterized by comprising the following steps: the method comprises the following steps:
(1) weighing 2g of gadolinium-iron sample into a 100ml volumetric flask, slowly adding 10ml of hydrochloric acid with 50 percent of volume fraction to dissolve the gadolinium-iron sample, controlling the temperature at 37 ℃ in the dissolving process, and after complete dissolution, fixing the volume to a scale with distilled water to obtain a solution A; taking 10ml of hydrochloric acid into a 100ml volumetric flask, and then using distilled water to fix the volume to a scale to obtain a solution B; the granularity of the gadolinium iron sample is less than 2mm, and the gadolinium iron sample is obtained by manually polishing a surface layer to have a smooth surface and good metal luster;
(2) taking 20ml of the solution A obtained in the step (1) to a triangular flask of 250ml, then adding 10ml of mixed sulfuric-phosphoric acid, then dropwise adding 3-4 drops of sodium diphenylamine sulfonate indicator, titrating with a potassium dichromate standard solution with the concentration of 0.006mol/l until the solution becomes purple, namely, a terminal point, and reading the volume V of the used potassium dichromate standard solution 1 (ii) a Taking 20ml of the solution B obtained in the step (1) to a triangular flask of 250ml, then adding 10ml of mixed sulfuric-phosphoric acid, then dropwise adding 3-4 drops of sodium diphenylamine sulfonate indicator, titrating with a potassium dichromate standard solution with the concentration of 0.006mol/l until the solution becomes purple, namely, a terminal point, and reading the volume V of the used potassium dichromate standard solution 0 (ii) a The sodium diphenylamine sulfonate indicator is prepared by dissolving 0.5g of sodium diphenylamine sulfonate in every 100ml of distilled water;
(3) calculating the mass fraction of the iron in the gadolinium-iron sample according to the formula (1), wherein the unit is percent, and the formula (1) is as follows:
Example 5:
a method for measuring the iron content in gadolinium-iron alloy is characterized by comprising the following steps: the method comprises the following steps:
(1) weighing 2g of gadolinium-iron sample into a 100ml volumetric flask, slowly adding 10ml of hydrochloric acid with 50 percent of volume fraction to dissolve the gadolinium-iron sample, controlling the temperature at 39 ℃ in the dissolving process, and after complete dissolution, fixing the volume to scale with distilled water to obtain a solution A; taking 10ml of hydrochloric acid into a 100ml volumetric flask, and then adding distilled water to a constant volume to a scale to obtain a solution B; the granularity of the gadolinium iron sample is less than 2mm, and the gadolinium iron sample is obtained by manually polishing a surface layer to have a smooth surface and good metal luster;
(2) taking 20ml of the solution A obtained in the step (1) to a 250ml triangular flask, then adding 10ml of mixed sulfur and phosphorus acid, then dropwise adding 3-4 drops of sodium diphenylamine sulfonate indicator, titrating with a potassium dichromate standard solution with the concentration of 0.006mol/l until the solution becomes purple, namely, an end point, and reading the volume V of the used potassium dichromate standard solution 1 (ii) a Taking 20ml of the solution B obtained in the step (1) to a 250ml triangular flask, then adding 10ml of mixed sulfur and phosphorus acid, then dropwise adding 3-4 drops of sodium diphenylamine sulfonate indicator, titrating with a potassium dichromate standard solution with the concentration of 0.006mol/l until the solution becomes purple, namely, an end point, and reading the volume V of the used potassium dichromate standard solution 0 (ii) a The sodium diphenylamine sulfonate indicator is prepared by dissolving 0.5g of sodium diphenylamine sulfonate in 100ml of distilled water;
(3) calculating the mass fraction of the iron in the gadolinium-iron sample according to the formula (1), wherein the unit is percent, and the formula (1) is as follows:
Experimental example:
weighing 5 parts of gadolinium-iron alloy samples, respectively marking the samples as 1, 2, 3, 4 and 5, wherein the weight of each sample is 4g, then averagely dividing each sample into two parts, wherein the weight of each sample is 2g, one part of samples adopts a standard method to determine the iron content, namely, the part 4 of the chemical analysis method of rare earth industry standard XB/T617.4-2014 neodymium iron boron alloy of the people's republic of China is adopted: the potassium dichromate titration method in the iron content determination; the other part adopts the method for measuring the iron content in any gadolinium ferroalloy in the embodiment 1-5, and the measurement results are shown in Table 1.
Table 1 results of gadolinium-iron alloy sample determination in experimental examples using different methods for determining iron content
According to the results, compared with the existing method, the method for measuring the iron content in the gadolinium ferroalloy has the same measurement result, but the measurement time is greatly shortened, so that the iron content in the gadolinium ferroalloy can be timely and accurately measured, and the analysis and detection efficiency is improved.
Furthermore, it should be understood that although the present specification describes embodiments, not every embodiment includes only a single embodiment, and such description is for clarity purposes only, and it is to be understood that all embodiments may be combined as appropriate by one of ordinary skill in the art to form other embodiments as will be apparent to those of skill in the art from the description herein.
Claims (2)
1. A method for measuring the iron content in gadolinium-iron alloy is characterized by comprising the following steps: the method comprises the following steps:
(1) weighing 2g of gadolinium-iron sample into a 100ml volumetric flask, slowly adding 10ml of hydrochloric acid to dissolve the gadolinium-iron sample, controlling the temperature at 35-40 ℃ in the dissolving process, and after complete dissolution, fixing the volume to a scale with distilled water to obtain a solution A; taking 10ml of hydrochloric acid into a 100ml volumetric flask, and then using distilled water to fix the volume to a scale to obtain a solution B;
the volume fraction of the hydrochloric acid is 50%; the granularity of the gadolinium-iron sample is less than 2mm, and the gadolinium-iron sample is obtained by manually polishing the surface layer to obtain a gadolinium-iron sample with smooth surface and good metal luster;
(2) taking 20ml of the solution A obtained in the step (1) to a 250ml triangular flask, then adding 10ml of mixed sulfur and phosphorus acid, then dropwise adding 3-4 drops of sodium diphenylamine sulfonate indicator, titrating with a potassium dichromate standard solution with the concentration of 0.006mol/l until the solution becomes purple, namely, an end point, and reading the volume V of the used potassium dichromate standard solution 1 (ii) a Taking 20ml of the solution B obtained in the step (1) to a 250ml triangular flask, then adding 10ml of mixed sulfur and phosphorus acid, then dropwise adding 3-4 drops of sodium diphenylamine sulfonate indicator, titrating with a potassium dichromate standard solution with the concentration of 0.006mol/l until the solution becomes purple, namely, an end point, and reading the volume V of the used potassium dichromate standard solution 0 ；
(3) Calculating the mass fraction of iron in the gadolinium iron sample according to the formula (1), wherein the formula (1) is as follows:
2. The method for determining the iron content in the gadolinium ferroalloy according to claim 1, wherein the method comprises the following steps: the sodium diphenylamine sulfonate indicator in the step (2) is prepared according to the proportion that 0.5g of sodium diphenylamine sulfonate is dissolved in every 100ml of distilled water.
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