GB/T 15072.4-1994 Chemical analysis methods for precious metals and their alloys Determination of palladium content in palladium and silver alloys
Some standard content:
National Standard of the People's Republic of China
Chemical analysis methods for precious metals and their alloys
Determination of palladium content in palladium and silver alloys
Palladium,silver alloys-Determination of palladium content1 Subject content and scope of application
This standard specifies the method for the determination of palladium content in palladium and silver alloys. GB/T 15072.4-- 94
This standard is applicable to the determination of palladium content in PdIr10, PdIr18, PdAgCuAuPtZn30-14-10-10-1, PdAgCu68-27, PdAgCu58-32, PdAgCu65-20, PdAgCu52-28, PdAgCu54-21, AgPd20, AgPd60 alloys. Determination range: 4%~92%.
2 Reference standards
GB1.4 Standardization work guideline Chemical analysis method standard writing regulations 3 Method summary
Palladium-iridium alloy, palladium-silver-copper-gold-platinum-zinc alloy samples are dissolved in mixed acid, among which, palladium-silver-copper-gold-platinum-zinc alloy is precipitated with silver chloride to separate silver, and sodium nitrite is reduced to separate gold; palladium-silver-copper alloy and silver alloy samples are dissolved in nitric acid, among which, palladium-silver-copper alloy is precipitated with silver chloride to separate silver, silver alloy is complexed with ammonia water, and silver is separated by silver chloride precipitation after acetic acid acidification. In dilute hydrochloric acid medium, palladium is precipitated with dimethyl ethane, and the palladium content is determined by gravimetric method. 4 Reagents
4.1 Sodium chloride.
4.2 Hydrochloric acid (pl.19 g/ml).
4.3 Nitric acid (pl.42g/mL). bZxz.net
Z acid ((pl. 05 g/mL).
Ammonia water ((p0. 90 g/mL).
Hydrochloric acid (1+1).
Hydrochloric acid (1+9).
Hydrochloric acid (2+98).
Mixed acid: Mix three unit volumes of hydrochloric acid (4.2) with one unit volume of nitric acid (4.3). Prepare freshly before use. Ammonia water (1+1).
Sodium nitrite solution (100g/1).
Sodium nitrite solution (10g/L).
Sodium hydroxide solution (100g/1.).
Dimethylethylene glycol solution (10g/L). Use after filtering. 4.14
4.15Thymol blue index Indicator (1g/L): Weigh 0.1g of thymol blue in a 100mL beaker, add 2.2ml of sodium hydroxide solution, and dilute to 100mL with water.
5 Sample
GB/T15072.4---94
The sample is processed into chips, and finally degreased with acetone, washed, dried, and mixed. 6 Analysis steps
6.1 Sample
Weigh the sample according to the table below, accurate to 0.0001g. Palladium content, %
4. 005. 00
> 5. 00~-10. 00
>10. 00~15. 00
>15. 00~25. 00
>25. 00~40. 00
40.00~80.00
>80. 00~- 92. 00
Carry out two independent determinations and take the average value. 6.2 Determination
6.2.1 Dissolution
Sample amount, g
6.2.1.1 Place the palladium alloy sample in a 400ml beaker, add 10ml of mixed acid, cover with a watch glass, heat at low temperature until the sample is completely dissolved, rinse the watch glass and the wall of the cup with water, add 0.1g of sodium chloride, and evaporate at low temperature until it is nearly dry. Add 10mL of hydrochloric acid (4.2), and evaporate again until it is nearly dry, repeat twice.
6.2.1.2 Place the palladium-silver-copper-gold-platinum-zinc alloy sample in a 250mL beaker, add 25mlL of hydrochloric acid (4 .2), 5ml. nitric acid, cover surface III, heat at low temperature to dissolve, if silver chloride precipitation is found to wrap the sample, add hydrochloric acid (4.2) until it is completely dissolved. Blow water to wash the surface and the wall of the cup, add 0.1g sodium chloride, and evaporate at low temperature until it is almost dry. Add 10mL hydrochloric acid (4.2) and evaporate to nearly dry, repeat twice. 6.2.1.3 Place the palladium silver copper alloy sample in a 250mL beaker, add 10mL nitric acid, cover surface III, heat at low temperature until completely dissolved, blow water to wash the surface blood and the wall of the cup, add 0.1g sodium chloride, evaporate at low temperature until it is almost dry, add 10mL hydrochloric acid (4.2) and evaporate to nearly dry, repeat twice.
6.2.1.4 Place the silver alloy in a 250ml beaker and dissolve according to (6.2.1.3). 6.2.2 Separation
6.2.2.1 Add 10mL hydrochloric acid (4.2) and 200mL water to the residue (6.2.1.1), slowly add 15mL dimethylethylenediethanol solution under stirring, continue stirring for 3min, and let stand for 1h. 6.2.2.2 Add 4mL hydrochloric acid (4.6) and 100ml water to the residue (6.2.1.2), heat and boil until the silver chloride precipitate condenses, let stand for 4h in the dark, filter with dense filter paper, wash the beaker and precipitate with hydrochloric acid (4.8) six times, each time with 5mL; then wash the beaker and precipitate with water twice, each time with 5ml. Discard the precipitate and keep the filtrate. Add two drops of thymol blue indicator to the filtrate, adjust the solution from red to orange (pH 2) with sodium hydroxide solution, heat to boiling, add 10 mL of sodium nitrite solution (4.11), stir and continue boiling for 30 minutes until the gold precipitate condenses, filter with dense filter paper while hot, wash the beaker and precipitate with hot sodium nitrite solution (4.12) five times, each time with 5 mL. Then drip 5 mL of hydrochloric acid (4.6) on the edge of the beaker and filter paper respectively; finally, wash the beaker and precipitate with hot water ten times, each time with 5 mL, discard the precipitate, and keep the filtrate. Heat the filtrate to boil for 1 hour, evaporate at low temperature until almost dry, add 10mL hydrochloric acid (4.2), and evaporate again until almost dry, repeat three times, add 10ml hydrochloric acid 73
GB/T 15072.4--- 94
(4.2), 200ml water. Slowly add 10ml monomethylethylenediethanol solution while stirring, continue stirring for 3min, let stand for 1h, 6.2.2.3 Residue 6.2.1.3) Separate the silver according to (6.2.2.2). Add 8mL hydrochloric acid (4.2) to the filtrate to adjust the solution volume to 200ml. Add 10ml dimethylethylenediethanol solution while stirring, continue stirring for 3min, and let stand for 1h. 6.2.2.4 Add 100 ml of water to the residue (6.2.1.4). Add about 10 ml of ammonia water (4.10) while stirring continuously. When the yellow color of the solution disappears, if a pink precipitate is produced, slightly heat it to dissolve the precipitate. Then slowly add acetic acid until the acidity of the solution is 6. Add 5 ml of acid (4.7), stir for 3 minutes, boil for 3 minutes, remove it, and keep it away from light and quiet for 4 hours. Filter it with dense filter paper. Wash the beaker and the precipitate with hydrochloric acid (4.8) six times, each time with 5 ml. Then wash the beaker and the precipitate with water twice, each time with 5 ml. Discard the precipitate, keep the filtrate, stir the filtrate evenly, add 5 ml of hydrochloric acid (4.2), heat and boil for 5 minutes, remove it and cool it to room temperature, add water to a total volume of 200 ml, slowly add 10 ml of dimethylethylenediethanol solution while stirring, continue stirring for 3 minutes, and let it stand for 1 hour. 6.2.3 Filtration
Filter the dimethylethylenedipalladium precipitate (6, 2.2.1 or 6.2.2.2, 6.2.2.3, 6.2.2.4) through vacuum filtration on a 110°C dried No. 4 glass sand filter cloth, wash the beaker and the precipitate with hydrochloric acid (4.8) ten times, using 5 ml each time. Use a glass rod with a rubber head to wipe the edge of the beaker, and then use hot water below 85°C to wash the beaker and the precipitate five times, using 5 ml each time. 6.2.4 Weighing
Dry the crucible (6.2.3) at 110°C for 1 hour, take it out and put it in a desiccator to cool for 30 minutes, weigh it, and dry it again until it is constant weight. 7 Expression of analytical results
Calculate the autogenous content of palladium according to the following formula:
Pd(%) = (mz=m2×0. 3161 × 100rn
Where: m-mass of methyl ethyl palladium and crucible·g; m-mass of ground,.
m-mass of sample";
conversion factor of dimethyl ethyl palladium to palladium. 0. 316 1 -
The result should be expressed to the decimal place
8Tolerance
The difference of analysis results between experimental cases should not be greater than 0.30%. Additional remarks:
This standard was proposed by China Nonferrous Metals Industry Corporation. This standard was drafted by Kunming Precious Metals Research Institute. This standard was drafted by Kunming Precious Metals Research Institute. The main drafter of this standard is Zhou Liwen.
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