GB/T 4324.8-1984 Chemical analysis of tungsten - Determination of nickel content by dimethylglyoxime spectrophotometry GB/T4324.8-1984 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Chemical analysis method of tungsten
Determination of nickel content by dimethylglyoxaline photometric method
Methods for chemical analysis of tungstenThe dimethylglyoxaline photometric method forthe determination of nickel contentUDC 669.27 :543
.42±546.74
GB 4324.8--84
This standard is applicable to the determination of nickel content in tungsten powder, tungsten bar, tungsten trioxide, tungstic acid and ammonium paratungstate. Determination range: 0.0004-0.01%. This standard complies with GB1467-78 "General Principles and General Provisions of Standards for Chemical Analysis Methods of Metallurgical Products". 1 Method Summary
The sample is melted with potassium pyrosulfate. Leach with citric acid-ammonium hydroxide. Extract with dimethylglyoxaline-chloroform at pH 8-9 and back-extract with 0.5N hydrochloric acid. In alkaline solution, in the presence of an oxidant, nickel forms a colored complex with dimethylglyoxime, and its absorbance is measured. 2 Reagents
Potassium pyrosulfate.
Hydrochloric acid (0.5N).
Hydrochloric acid (1 +9).
Ammonium hydroxide (specific gravity 0.90).
Ammonium hydroxide (1+9).
Ammonium hydroxide (1+99).
Chloroform.
Sodium potassium tartrate solution (20%). bzxZ.net
Citric acid solution (50%).
Diketone ethanol solution (1%).
Sodium hydroxide solution (15%).
Sodium hydroxide solution (5%).
Diketone solution (3%): Prepared with sodium hydroxide solution (5%). Ammonium persulfate solution (5%).
Nickel standard solution
Weigh 0.[000g of metallic nickel (99.99%), place it in a 250ml beaker, add 10ml of nitric acid (1+1), heat to dissolve, cool, blow water to wash the surface and the wall of the beaker, heat and boil for a while, cool, transfer to a 1000㎡1 volumetric flask, dilute with water to the scale, and mix. This solution contains 0.10mg nickel in 1ml.
2.15.2 Transfer 5.00ml of nickel standard solution (2.15.1), place it in a 250ml volumetric flask, dilute with water to the scale, and mix. This solution contains 2μg nickel in 1ml.
3 Test sample
3.1 The tungsten bar should be powdered and pass the 120-month net. 3.2 After weighing the pigeon strips, chromium powder and ammonium tungstate, heat them on an electric furnace for 30 minutes, and then move them into a high temperature furnace and burn them at 750℃ for 30 minutes to convert them into tungsten trioxide.
Analysis steps
4.1 Determination quantity
GB 4324.8-84
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. 4.2 Sample whole
Weigh Q.1000-1,000g sample
4.3 Blank test
Carry out a blank test with the sample.
4.4 Determination
4.4.1 Place the sample (4.2) in 30ml of porcelain, add 4g of potassium pyrosulfate (2.1), place in a medium to remove moisture, transfer to a high-temperature furnace at 750-800℃ to melt, take out and cool. 4..2 Use 10ml of citric acid solution (2.9) to take out the molten block, wash the molten block into a 250ml beaker 1, add 15ml of ammonium hydroxide (2.4), heat to dissolve the molten block, and cool. Use ammonium hydroxide (2.5) and hydrochloric acid (2.3) to adjust the pH of the test solution to 8-9 (check with a wide range pH test paper), add 60ml of acid to a separatory tube, add water to about 30ml, add 1ml of potassium sodium alcohol solution (2.8), and mix. Use ammonium hydroxide (25) and hydrochloric acid (2.3) to adjust the pH of the test solution to 8-9 (check with a wide range pH test paper), add 1ml of ethanol solution (2.10), and mix.
4.43 Add 10 ml of dichloromethane (2.7), shake for 2 min, let stand and separate, transfer the organic phase to another separatory funnel, add 5 ml of dichloromethane to the aqueous phase, shake, extract for 2 min, let stand and separate, combine the organic phases, and remove the aqueous phase. Wash the organic phase once with 10 ml of ammonium hydroxide (2.6), let stand and separate, and discard the aqueous phase. 4.4.4 Add 5 ml of hydrochloric acid (2.2) to the organic phase r for back extraction, shake for 2 min, let stand and separate, discard the organic phase, and transfer the aqueous phase to a 10 ml volumetric flask.
4.45 Add 1 ml of potassium sodium alcohol solution (2.8) (washed from the separatory funnel), 1 ml of sodium hydroxide solution (2.11), 1 ml of ammonium persulfate solution (2.14), and 1 ml of diacetyl solution (2.13). Each reagent must be mixed. Dilute with water to the mark, mix, and let stand for 20 minutes.
4.46 Transfer part of the solution to a 2 cm colorimetric tube, and measure its absorbance at a wavelength of 520 mm on a spectrophotometer with water as reference. 4.4. Subtract the absorbance of the blank sample prepared with the sample. Find the corresponding amount from the curve. 4.5 Drawing of the working curve
4.5.1 Transfer 0.00, 1.50, 3.00, 4.50, 6.00, and 7.50 ml of the nickel standard solution (2.15.2) to a set of 60 ml dispensing tanks, adjust the volume to about 30 ml with water, add 1 ml of potassium sodium tartrate solution (2.8), mix well, adjust the test solution to pH 8-9 with ammonium hydroxide (2.5) and hydrochloric acid (.3) (check with a wide pH test paper), add 1 ml of diethanol solution (2.10), and mix well. Let stand for a while. The following is carried out according to 4.4.3 to 4.4.6, measure the absorbance, and subtract the absorbance of the reagent blank. Draw a working curve with the nickel content as the horizontal axis and the absorbance as the vertical axis. 6 Calculation of analysis results
Calculate the nickel content as follows:
Ni(%)=
Where: mi——Nickel content found from the working curve, g, sample weight, g.
6 Allowable difference
The difference in analysis results between laboratories should not be greater than the allowable difference listed in the following table. 25
Additional Notes:
0.00040~0.00080
>0.00080~0.0015
>0.0015~0.0025
>0.0025-0.0040
>0.004~0.010
This standard is proposed by the Ministry of Metallurgical Industry of the People's Republic of China. This standard is drafted by Zhuzhou Cemented Carbide Factory. This standard is drafted by Nanken Cemented Carbide Factory
Chong Xu Lao
The main drafters of this standard are Sun Xiaoyong and Shu Xiaodan. From the date of implementation of this standard, the former Ministry of Metallurgical Industry Standard YB895-77 "Chemical Analysis Method of Tungsten" will be invalidated. 26
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