This standard specifies the determination method of iron content in tantalum and niobium. This standard is applicable to the determination of iron content in tantalum and niobium, and also to the determination of iron content in their hydroxides. The determination range is: >0.02% to 0.3%. GB/T 15076.4-1994 Chemical analysis method of tantalum and niobium Determination of iron content GB/T15076.4-1994 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Chemical analysis methods of tantalum and niobium
Determination of iron content
Methods for chemical analysis of tantalum and niobium-Determination of iron content1 Subject content and applicable range
This standard specifies the method for determining the iron content in tantalum and niobium. GB/T 15076.4--94
This standard is applicable to the determination of the iron content in tantalum and niobium, and also to the determination of the iron content in their hydroxides, with a determination range of 0.02% to 0.3%.
2 Reference standards
GB1.4 Standardization work guidelines for the preparation of chemical analysis method standards GB1467 General principles and general provisions for chemical analysis method standards for metallurgical products GB7729 General principles for spectrophotometric methods for chemical analysis of metallurgical products 3 Principle of the method
The sample is dissolved with hydrofluoric acid and nitric acid, tartaric acid-boric acid complexes the main body and fluorine, and iron (I) is reduced to iron (I) with hydroxylamine hydrochloride. At about pH 5, divalent iron ions react with 1,10-phenanthroline to form a red complex, and its absorbance is measured at a wavelength of 510nm on a spectrophotometer. 4 Reagents
4.1 Hydrofluoric acid (pl.14g/mL).
4.2 Nitric acid (pl.42g/mL).
4.3 Ammonia water (p0.90g/mL).
4.4 Tartaric acid-boric acid solution: Weigh 20g tartaric acid and 6g boric acid, place in a 250mL beaker, add water to dissolve and dilute to 100ml. Mix well.
4.5 Hydroxylamine hydrochloride solution (100g/L).
4.6 1,10-phenanthroline ethanol solution (2.5g/L). 4.7 Iron standard stock solution: Weigh 0.1000g metallic iron, place in a 150ml beaker, add 50mL hydrochloric acid (1+1), heat to dissolve, cool, transfer to a 1000mL volumetric flask, dilute to scale with water, and mix well. This solution contains 100μg iron in 1mL. 4.8 Iron standard solution: Transfer 25.00mL of iron standard stock solution (4.7) to a 100mL volumetric flask. Dilute to scale with water and mix well. This solution contains 25μg iron in 1mL.
4.9 Congo red test paper.
5 Instruments
Spectrophotometer.
Approved by the State Administration of Technical Supervision on May 9, 1994 and implemented on December 1, 1994
6 Analysis steps
6.1 Determination quantity
GB/T 1 5076. 4-94
Weigh two samples, measure independently and take the average. 6.2 Samples
Weigh the sample according to Table 1, accurate to 0.0001g. Table 1
Iron content
≥0.02～0.180
>0. 180~0.30
6.3 Blank testbzxz.net
Carry out a blank test with the sample.
6.4 Determination
Total volume of test solution
Volume of test solution
6.4.1 Place the test material (6.2) in 30mL of platinum, add a few drops of water to moisten, add 3mL of hydrofluoric acid (4.1), add nitric acid (4.2) dropwise, wait for the violent reaction to stop, heat at low temperature until the test material is completely dissolved, continue to evaporate until a precipitate is precipitated, then add hydrofluoric acid (4.1) dropwise to dissolve the precipitate. Cool, add 10ml. tartaric acid-boric acid solution (4.4), transfer to a 50mL volumetric flask, dilute to scale with tartaric acid-boric acid solution (4.4), and mix well. According to Table 1, take the test solution and place it in a 50mL volumetric flask. 6.4.2 Add 5mL of hydroxylamine hydrochloride solution (4.5) and put a small piece of Congo red test paper (4.9). Add ammonia water (4.3) until the test paper turns purple-red, add two drops of excess, add 2mL of 1,10-phenanthroline solution (4.6), dilute to the scale with water, and mix. Heat in a water bath at about 80℃ for 5min, take out, and cool to room temperature.
6.4.3 Transfer part of the solution into 1cm absorption III, use water as reference, and measure its absorbance at a wavelength of 510nm on a spectrophotometer. 6.4.4 Subtract the absorbance of the blank solution accompanying the sample and find the corresponding amount of iron from the working curve. 6.5 Drawing of working curve
6.5.1 Pipette 0, 0.50, 1.00, 2.00, 4.00, 6.00, 8.00mL of iron standard solution (4.8) into a set of 50mL volumetric flasks respectively, add 5mL of tartaric acid-boric acid solution (4.4) and mix well. The following operations are carried out according to 6.4.2~6.4.3. 6.5.2 Subtract the absorbance of the reagent blank, and draw the working curve with the iron content as the horizontal axis and the absorbance as the vertical axis. Calculation and expression of analysis results
Calculate the percentage of iron according to the following formula:
Fe(%)=m, · V. X10-s
Where: mi—the amount of iron found from the working curve, ug: Va—the total volume of the test solution, mL;
V,-the volume of the test solution taken, mL;
mo——the mass of the test material, g.
8 Allowable difference
The difference in the analysis results between laboratories should not be greater than the allowable difference listed in Table 2. 494
Additional instructions:
Iron content
>0. 020~0. 045
>0. 045~0. 100
>0.100~0.300
GB/T15076.4—94
This standard is proposed by China Nonferrous Metals Industry Corporation. This standard is drafted by Ningxia Nonferrous Metals Smelter. This standard was drafted by Ningxia Nonferrous Metals Smelter. The main drafter of this standard is Zhang Lanfen.
From the date of implementation of this standard, the former Ministry of Metallurgical Industry of the People's Republic of China issued the Ministry of Standard YB942 (1) -78 Determination of Iron Content in Molybdenum (O-phenanthroline Absorption Spectrophotometry)" will be invalid.
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