GB/T 4324.5-1984 Chemical analysis of tungsten - Molybdenum blue photometric method for the determination of arsenic
Some standard content:
National Standard of the People's Republic of China
Chemical analysis method of tungsten
Determination of arsenic content by molybdenum blue photometric method
Methods for chemical analysis of tungstenThe molybdenum blue photometric method for thedetermination of arsenic contentUDC 869.27 :543
-42:546.19
GB 4324.5—84
This standard is applicable to the determination of arsenic content in tungsten powder, tungsten bar, tungsten dioxide, tungstic acid and ammonium paratungstate. The determination range is 0.00008～0.020%. This standard complies with GB1467-78 "General Principles and General Provisions of Chemical Analysis Methods for Metallurgical Products". 1 Method Summary
The sample is dissolved in hydrogen peroxide or sodium hydroxide, with beryllium hydroxide as carrier, and precipitated with ammonium chloride. Then it is separated by iodide extraction and photometric determination is carried out with arsenic molybdenum blue.
Hydrochloric acid (specific gravity 1.19), high-grade pure.
2.2 Nitric acid (specific gravity 1.42), high-grade pure. 2.3 Benzene.
2.4 Hydrogen peroxide (specific gravity 1.10).
2.5 Ammonium hydroxide (specific gravity 0.90).
Ammonium hydroxide (1+50).
2.7 Sulfuric acid (10N),
z.8 Sulfuric acid (0.8N).
2. Sodium hydroxide solution (10%), high-grade pure. 2.10 Sulfuric acid plating solution: weigh 20g beryllium sulfate (BeSO, ·4HzO), place in a beaker, add 200ml water to dissolve, add 20ml sulfuric acid (1+1), dilute with water to 1000ml. This solution contains 1mg beryllium per ml. 2.11 Disodium ethylenetetraacetic acid (EDTA) solution (10%): weigh 50g EDTA, place in a beaker, add about 400ml water, heat to dissolve, cool, dilute with water to 500ml; mix well. 2.12 Potassium iodide solution (5M): weigh 83g potassium iodide, place in a beaker, add appropriate amount of water to dissolve and dilute to 100ml, mix. Prepare when used.
2.13 Extraction washing solution: mix ten parts of sulfuric acid (2.7) with one part of potassium iodide solution (2.12). Prepare when used. 2. 14
Potassium permanganate solution (1.5%).
Sodium sulfite solution (3%). Prepare when needed. 2.15
2.16 Ammonium sulfate solution (1%).
Sulfuric acid solution (0.06%).
2.18 Arsenic standard solution
2.18.1 Weigh 0.1320g of arsenic trioxide standard reagent previously dried at 110°C, place in a beaker, add 2ml sodium hydroxide solution (1N) to dissolve, slowly add 10ml nitric acid (specific gravity 1.42), steam on a hot plate below 130°C, keep warm for about 30 minutes and cool. Add water to dissolve, transfer to a 100ml volumetric flask with water and dilute to full scale, mix. This solution contains 1.0mg arsenic in 1ml. Issued by the National Bureau of Standards on April 12, 1984
Implemented on August 1, 1985
GB 4324. 5-84
2.18.2 Take 5.00 ml of the standard solution (2.18.1) and place it in a 1000 ml volumetric flask, dilute to the mark with water, and mix. This solution contains 5 μg of arsenic in 1 ml.
3 Sample
The tungsten bar should be crushed and passed through a 120-month sieve.
Analysis steps
4.1 Determination quantity
Three samples should be weighed for determination during analysis. The measured values should be within the allowable indoor difference and the average value should be taken. Sample quantity
Weigh the sample quantity according to Table 1.
Arsenic, %
0.00008-0.0008
>0.0008~0.0020
>0,0020 ~0.0060
>0.0060-0.020
Blank test
Carry out blank test with the sample.
4.4 Determination
Sample quantity, *
4.4:1 Tungsten powder, tungsten bar
4.4.1.1 Place the sample (4.2) in a 300ml quartz beaker, add 2ml water to moisten it, cover it with a watch glass, and slowly add 10-40ml hydrogen peroxide (2.4) while shaking it continuously. Leave it or heat it slightly. After the violent reaction weakens, add 5ml hydrogen peroxide (2.4) and dissolve it until it is clear. After boiling, evaporate it to dryness at a low temperature, add 5-15ml sodium hydroxide solution (2.9), and heat it to dissolve it until it is clear. 4.4.1.2 Add 5ml nitric acid (2.2) and 5ml hydrochloric acid (2.1), and heat it on a hot plate to keep it slightly boiling for about 20min (shake it several times to precipitate yellow tungstic acid). Add 10 ml of beryllium sulfate solution (2.10), add 22 ml (44 ml for 2 g sample) of near-boiling EDTA solution 42.11), and add near-boiling water to a volume of about 130 ml. 4.4.1.3 Heat on a hot plate until it is nearly boiling. While keeping warm, add tungstic acid (2.5) until tungstic acid dissolves and beryllium oxyfluoride precipitates, then filter 10 ml. Boil 1 to 2 bottles of water and cool in cold water. Filter with medium-speed fixed filter paper with a diameter of about 9.5 cm, wash the beaker and precipitate 5 to 6 times with ammonium hydroxide (2.6), and then wash with water 5 to 6 times. Discard the filtrate and washings. 4.4.1.4. Dissolve the precipitate in the separatory funnel with 30 ml of sulfuric acid (2.7) in several times (at the same time, dissolve the precipitate in the quartz beaker and add it). Add 3 ml potassium iodide solution (2.12), mix, add 20 ml benzene (2:3), shake for 2 min, let stand to separate, discard the aqueous phase, wash the organic phase with 10 ml extraction washing solution (2.13) and shake for 10 s, discard the aqueous phase, and repeat the washing once. Add 8.00 ml sulfuric acid (2.8), shake for 1 min, let stand to separate, and put the aqueous phase into a 25 ml volumetric flask. Then use 10 ml water to extract for 1 min, and put the aqueous phase into a volumetric flask. 4.4.1.5 Add about 0.8 ml potassium permanganate solution (2.14) dropwise until it turns stable red, and let stand for 5 min. Add sodium sulfite solution (2.15) dropwise until the red color disappears, shake the solution to dissolve all the precipitated iodine and fade, and then add 1 to 2 drops in excess. Add 0.25 ml ammonium sulfate solution (2.16) and 1.25 ml sulfuric acid solution (2.17), dilute to the scale with water, and mix well. Place in a boiling water bath and heat for 10 minutes. Take out and cool to room temperature with cold water. Transfer part of the solution into a 3 cm colorimetric tube and measure its absorbance at a wavelength of 850 nm using water as a reference on a spectrophotometer. 16
GB4324.5—84
4.4.1.6 Subtract the absorbance of the sample from the air. Find the corresponding amount from the workbook. 4.4.2 Dove trioxide, tungstic acid, ammonium paratungstate Place the sample (4.2) in a 300 ml quartz beaker, add 5 to 15 ml of sodium hydroxide solution (2.9), and heat to dissolve until clear. Proceed as in 4.4.1, 2 to 4.4.1.5. 4.5 Drawing of working curve
Pipette 0.00, 0.20, 0.40, 0.60, 1.00, 2.00, 3.00, 4.00 ml of arsenic standard solution (2.18.2) and place them in 30 ml beakers respectively. Add 5 ml of FDTA solution (2.1H) and 10 ml of sulfuric acid solution (2.10). Add water to a volume of about 130 ml. Proceed as in 4.1.3 to 4.4.1.5, measure the absorbance, and subtract the absorbance of reagent air H. Draw the working curve with the amount of arsenic as the horizontal axis and the absorbance as the vertical axis.
Calculation of analysis results
Calculate the arsenic content according to the following formula
As (%):
Wherein: m
Allowable error
Arsenic amount found from the plot, g:
Sample amount, g.
The difference in analysis results between experimental cases should not be less than the allowable error listed in Table 2. Table 2
0.00008 ~ 0. 00050
>0,00050-0.00080wwW.bzxz.Net
>0.00080 ~0.00150
0. 0015 ~ 0. 0050
0. 0050 ~0.0200
Additional remarks:
This standard is proposed by the Ministry of Metallurgical Industry of the People's Republic of China. This standard was drafted by Zhuzhou Cemented Carbide Factory. This standard was drafted by the Iron and Steel Research Institute.
The main drafters of this standard are Zhu Chengde and Ren Guiyuan.
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