GB/T 15072.8-1994 Chemical analysis methods for precious metals and their alloys - Determination of copper content in gold, 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 copper content in gold, palladium and silver alloys
Gold,palladium and silver alloys---Determination of copper content1 Subject content and scope of application
This standard specifies the method for determination of copper content in gold, palladium and silver alloys. GB/T 15072. 8-- 94
This standard is applicable to AuAgCu20-20, AuAgCu35-5, AuAgCu13-20, AuCuNiZn22-2.5-1, AuCuNiZn30-30.7. AuCuNiZnMn18-1.8-0.7-0.03. PdAgCu65-20, PdAgCu54-21.PdAgCu68-27. Determination of copper content in PdAgCu52-28.PdAgCu58-32, PdAgCuAuPtZn30-14-10-10-1, AgCu10, AgCu12.5, AgCuV10-0.2, AgCuNiA120-?- alloys. Determination range: 4% to 33%. 2 Reference standards
GB1.4 Standardization work guidelines Chemical analysis method standard preparation regulations GB1467 General principles and general provisions for chemical analysis method standards for metallurgical products 3 Method summary
Silver alloy samples are dissolved in nitric acid, and excess Na?EDTA is added to complex with copper, nickel, vanadium and aluminum; palladium silver copper alloy is dissolved in nitric acid, gold alloy and palladium silver copper gold platinum zinc alloy samples are dissolved in mixed acid, gold-containing alloys are reduced with sulfurous acid to separate gold, palladium-containing alloys are precipitated with dimethylethylenediamine to separate palladium, and excess Na.EDTA is added to complex with copper, nickel, zinc and manganese. Use hexamethylenetetramine as buffer and xylenol orange as indicator, back titrate with lead standard titration solution at pH 5.8. Add sulfuric acid, ascorbic acid and 1,1O-phenanthroline solution to precipitate EDTA complexed with copper, then titrate with lead standard titration solution to determine the amount of copper. 4 Reagents
4.1 Sodium chloride.
4.2 Hexamethylenetetramine.
4.3 Sulfurous acid (pl.03g/ml.).
4.4 Hydrochloric acid (pl.19g/mL).
4.5 Nitric acid (pl.42g/ml.). bzxZ.net
Ammonia water (p0.90g/mL).
Mixed acid: Mix 3 units of hydrochloric acid (4.4) with 1 unit of nitric acid (4.5). Prepare it when needed. 4.7
4.8 Mixed acid: 30 units of hydrochloric acid (4.4) and 1 unit of nitric acid (4.5). Prepare before use. 4.9
Hydrochloric acid (1+1).
) Hydrochloric acid (1+99).
4.11 Nitric acid (1+1).
4.12 Ammonia water (1+1).
Approved by the State Administration of Technical Supervision on May 11, 1994 and implemented on December 1, 1994
GB/T 15072.8—94
Ethylaminetetraacetic acid disodium (Na2EDTA·2H,O) solution (0.01mol/L). 4.14 Ethylenediaminetetraacetic acid disodium solution (0.02mol/L). 4.15
Ethylenediaminetetraacetic acid disodium solution (0.03mol/L). 4.16Thiourea solution (100/L).
4.17Ascorbic acid solution (50g/L).
4.181,10-phenanthroline ethanol solution (2g/L). Dimethylethylenediethanol solution (10g/). 4.19
4.20Copper standard solution: Weigh 2.0000g of metallic copper into a 250mL beaker, add 20ml of nitric acid (4.11), heat until completely dissolved, transfer to a 2000ml volumetric flask, dilute to scale with water, and mix well. This solution contains 1mg of copper per mL. 4.21 Lead standard titration solution
4.21.1 Preparation: Weigh 4.144g of lead into a 250ml beaker, add 20ml of nitric acid (4.5), heat until the lead is dissolved, and evaporate 23ml. Transfer to a 2000ml volumetric flask, dilute to scale with water, and mix. 4.21.2 Calibration: Calibration is carried out in parallel with the determination of the sample. Transfer three portions of the copper standard solution (see Table 1) into 250ml beakers, add 25ml of NazEDTA (concentration see Table 1). Add water to a total volume of 100ml, 4g of hexamethylenetetramine, 5 drops of xylenol orange solution, add ammonia water (4.12) until the solution turns purple-red, and then add hydrochloric acid (4.9) until the solution turns from purple-red to yellow-green. Add 2-3 drops of excess (pH 5.8) and titrate with lead standard titration solution to the endpoint (when the Cu content is ≤ 10 ng, the endpoint changes from yellow-green to purple-red; when the Cu content is ≥ 10 mg, the endpoint changes from green to purple.) Without counting
, add 20 mL of thiourea solution, 5 mL of ascorbic acid solution and 5 drops of 1,10-phenanthroline solution to the solution, stir well, and let stand for 10 min. Adjust the solution to pH 5.8 with ammonia water (4.12), and titrate with lead standard titration solution until the solution changes from yellow to red as the endpoint. The extreme value of the volume of lead standard titration solution consumed by the parallel determination should not exceed 0.05 mL. Take the average value. Perform a blank test together with the calibration.
AgCu10,AgCu12-5,AuAgCu35-5.AgCuV10-0. 2PdAgCu65-20.PdAgCu54-21.AuAgCu20-20AuCuNiZnMn18-1.8-0.7-0.03.AgCuNiAl20-2-1PdAgCuAuPtZn30-14-10-10-1.AuCuNiZn22-2.5-1PdAgCu52-2. 8,PdAgCu68-27.PdAgCu58-32AuCuNiZn30-3-0.7
According to formula (1), calculate the actual concentration of the lead standard titration solution: Calibration copper standard solution
Volume mL
(V, -V.) × 0. 063 55
Formula: c
actual concentration of lead standard titration solution, mol/L-the mass of copper in copper standard solution.g; V.the volume of lead standard titration solution consumed in calibration, mLV. .the volume of lead standard titration solution consumed in blank test, mL; NazEDTA concentration
0.06355--the mass of copper in grams equivalent to 1.00ml lead standard titration solution c (Pb) 1.000mol/L 4.22 cresol orange solution (2g/L).
5 sample
the sample is processed into debris, and finally degreased with acetone, washed, dried and mixed. 92
6 Analysis steps
6.1 Test material
GB/T 15072.8--94
Weigh about 0.1g of sample, accurate to 0.0001g. Perform two independent determinations and take the average value. 6.2 Blank test
Perform a blank test with the test material.
6.3 Determination
6.3.1.1 Place the gold-silver-copper and palladium-silver-copper-gold-platinum-zinc alloy test materials in 250ml and 400ml beakers respectively, add 40ml of mixed acid (4.8), cover the surface with blood, heat at low temperature until the test material is completely dissolved, add 0.1g of sodium chloride, and evaporate to nearly dryness. Add 5ml of hydrochloric acid (4.9) and evaporate to nearly dryness, repeat three times. Add 4 ml hydrochloric acid (4.9) and 100 ml water to the residue of gold, silver and copper samples; add 4 ml hydrochloric acid (4.4) and 200 ml water to the residue of palladium, silver, copper, gold, platinum and zinc samples.
6.3.1.2 Place the gold, copper, nickel, zinc and gold, copper, nickel, zinc and manganese alloy samples in a 250 ml beaker, add 40 ml mixed acid (4.7), cover the surface with blood, and heat at low temperature until the samples are completely dissolved. Add 0.1 g sodium chloride and evaporate to nearly dryness. Add 5 ml hydrochloric acid (4.9) and evaporate to nearly dryness, repeat the same process. Add 4 ml hydrochloric acid (4.9) and 100 ml water to the residue. 6.3.1.3 Place the palladium, silver and copper alloy sample in a 400 ml beaker, add 10 ml nitric acid (4.5), cover the surface III, and heat at low temperature until the samples are completely dissolved. Add 0.1 g sodium chloride and evaporate to nearly dryness. Add 5mL hydrochloric acid (4.9) and evaporate until almost dry, repeat three times. Add 4mL hydrochloric acid (4.4) and 200mL water to the residue. Boil the test solution for 15min, remove, cool, and rinse the watch glass and the wall of the cup with water. 6.3.1.4 Place the silver alloy sample in a 250mL beaker, add 4mL nitric acid (4.11), cover with watch glass, and heat until the sample is completely dissolved. Remove, cool, and rinse the watch glass and the wall of the cup with water. In the following, the silver-copper-vanadium test solution is as in 6.3.2.3; silver-copper, silver-copper-nickel-aluminum test solutions are titrated according to 6.3.3.
6.3.2 Test solution treatment
6.3.2.1 Boil the test solution (6.3:1.1 or 6.3.1.2), remove it, add sulfurous acid (see Table 2) and boil it slightly for 30 minutes, remove it. Cool it, and rinse the surface III and the cup wall with water.
6.3.2.2 Add 10mL of dimethylethylene dichloride solution to the palladium-containing alloy test solution (6.3.1.3, 6.3.2.1), stir it well, and let it stand for 30 minutes. Filter it with dense filter paper, wash the beaker and precipitate with hydrochloric acid (4.10) five times each, and then wash the precipitate with hot water (below 80℃) five times. Evaporate the filtrate to 50mL, remove it, and cool it. Filter the precipitate with filter paper, and wash the beaker and precipitate with water five times each. 6.3.2.3 Add 5 mL of hydrochloric acid (4.9) to the silver-copper-vanadium alloy test solution (6.3.1.4) and evaporate to near dryness, repeat three times. Add 4 mL of hydrochloric acid (4.9). 100 mL of water, slightly boil for 15 min, condense the silver chloride precipitate, remove, let stand for 2 h, filter with dense filter paper, wash the beaker and precipitate with hydrochloric acid (4.10) 8 times each. Evaporate the filtrate to a volume of nearly 20 mL, remove, add 25 mL of NazEDTA (4.13), add water to a total volume of 50 mL, adjust to pH 3-4 with ammonia water (4.6), add 5 mL of ascorbic acid solution, boil for 5 min, remove, cool, and rinse the watch glass and cup with water. Table 2
Amount of gold, mg
>30～40
>40～50
>50～60
>60～70
6.3.3 Titration
Volume of sulfurous acid added, ml
Add 25mL of Na,EDTA (concentration see Table 1. No Na2EITA is added to the silver-copper-vanadium alloy test solution) to the test solution (6.3.1.4, 6.3.2.1, 6.3.2.2, 6.3.2.3), add water to a total volume of 100mL, and add 4g hexamethylenetetramine, 5 drops of xylenol orange solution, add ammonia water (4.12) until the solution turns purple-red, then add hydrochloric acid (4.9) and nitric acid (4.11) until the solution changes from purple-red to yellow-green 93
GB/T15072.8-94
color, then add 2-3 drops in excess (solution pH 5.8), and titrate with lead standard titration solution to the endpoint (when the Cu content is ≤10mg, the first endpoint changes from yellow-green to purple-red, and when the Cu content is ≥10mg, the first endpoint changes from green to purple). Do not count. Add 20mL thiourea solution, 5ml ascorbic acid solution and 5 drops of 1,10-phenanthroline solution to the solution, stir well, let stand for 10min, adjust the solution pH to 5.8 with ammonia water (4.12), and titrate with lead standard titration solution until the solution changes from yellow to red as the endpoint. 7 Expression of analysis results
Calculate the percentage of copper according to formula (2):
Cu(%) ms×(VV)× 0. 063 55 × 100mo
Wherein: c——actual concentration of standard lead titration solution, mol/l; V2——volume of standard lead titration solution consumed in titrating the test solution, ml., V3——volume of standard lead titration solution consumed in blank test (6.2), mL; mo——mass of the sample, g;
0.06355——mass of copper in grams equivalent to 1.00mL standard lead titration solution Cc(Pb2)=1.000mo1/1.3. The result should be expressed to two decimal places.
8 Allowable difference
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 3. Table 3
Copper content
4.00~10.00
≥10.00～20. 00
>20.00~33.00
Additional remarks:
This standard was proposed by China Nonferrous Metals Industry Corporation. This standard was drafted by Kunming Precious Metals Research Institute. The main drafter of this standard is Julia.
Allowance
(2)
From the date of implementation of this standard, the former Ministry of Metallurgical Industry Standard YB946 (Au-8)-78 "Chemical Analysis Method for Gold, Silver and Copper Alloys". YB946 (Ag-8)-78 "Chemical Analysis Method for Silver, Copper and Vanadium Alloys" shall be invalid. 94
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.