title>GB/T 15249.2-1994 Chemical analysis of gold alloys - EDTA titration method for determination of silver content - GB/T 15249.2-1994 - Chinese standardNet - bzxz.net
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GB/T 15249.2-1994 Chemical analysis of gold alloys - EDTA titration method for determination of silver content
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Standard ID:
GB/T 15249.2-1994
Standard Name: Chemical analysis of gold alloys - EDTA titration method for determination of silver content
This standard specifies the method for determining the silver content in alloy gold. This standard is applicable to the determination of silver content in alloys (ore gold, smelting crude gold products and recycled gold, etc.). GB/T 15249.2-1994 Chemical analysis method for alloy gold - Determination of silver content by EDTA titration GB/T15249.2-1994 Standard download decompression password: www.bzxz.net
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National Standard of the People's Republic of China Crude Gold-Determinatlon of sllver Content-EDTA litrimetric method 1 Subject Content and Scope of Application This standard specifies the determination method of silver content in refined gold. GB/T15249.294 This standard is applicable to the determination of silver content in refined gold (ore gold, smelting crude gold products and recovered gold, etc.). Determination range: 0.5% to 40%. 2 Reference standards GB 1.4 Guidelines for standardization work Provisions for the preparation of chemical analysis methods GB1467 General principles and general provisions for chemical analysis methods for metallurgical products 3 Principles of the method Weigh a certain weight of the gold sample to be tested, dissolve it with nitric acid and hydrochloric acid, dilute it, filter it, dissolve the silver chloride precipitate with ammonia water, add nickel potassium cyanide to the ammonia solution, and the nickel is quantitatively replaced by silver. Take ammonium purpurate as an indicator and titrate the nickel with EDTA standard solution to calculate the silver content. 4 Reagents and materials 4.1 Nitric acid (ol.42 g/mL). Excellent grade. 4.2 Hydrochloric acid (pl.19 g/mL), excellent grade. 4.3 Nitrogen water (1+1). 4.4 Ammonium purpurate indicator: Weigh 0.3 g ammonium purpurate and 25 g sodium chloride, grind and mix well. 4.5 Nickel potassium solution (60g/L), weigh 15g of potassium nickel [KNi(CN)], dissolve with 200mL hot water, cool and dilute to 250mL (prepare when needed) 4.6 EDTA (ethylenediaminetetraacetic acid disodium) standard titration solution [c(EDTA)α0. 030 mol/L)]: weigh 11. 2 g FDTA (CiHtN(),Naz2H,0), dissolve with hot water, cool and transfer to a 1:000mL volumetric flask and dilute to the scale. 4.7 Pure silver, 99.99%. 4.8 Pure gold, 99.99%. 5 Analysis steps 5.1 Test material 5. 1. 1 Test material Weigh the test material according to Table 1, accurate to 0.0001. Approved by the State Technical Supervision Commission on October 7, 1994, 72 Implementation on August 1, 1995 5.1.2 Standard test material Content, % 0. 50~2. 00 >2. 00 ~~5. 00 >5.0~15. 00 ≥15.00~40.00 GB/T 15249.294 According to the chemical composition of the sample, prepare two standard test materials with pure gold (4.8) and pure silver (4.7). 5.2 Determination 5.2.1 Place the sample (5.1) in a 400 mL beaker, add 20 mL water, 5 ml nitric acid (4.1), cover with blood, and heat at low temperature to dissolve for 30 min. 5.2.2 Add 20 mL hydrochloric acid (4.2), heat at low temperature to completely dissolve the sample, and generate silver fluoride precipitate, remove, wash the blood and the beaker wall, cool to room temperature, dilute to 200 mL, heat at low temperature on a hot plate until the bath liquid is clear, so that the silver chloride condenses, remove and cool slightly. 5.2.3 Wash the blood and the beaker, filter with 9 cm medium-speed quantitative filter paper, rinse the silver chloride precipitate with warm water 2 to 3 times and transfer it to the funnel, wash the beaker 3 times, wash the precipitate 6 to 8 times until the filter paper is colorless. 5.2.4 Unfold the filter paper and put it back into the original beaker together with the silver chloride precipitate. Add 15 ml of ammonia water (4.3) while shaking continuously until the silver chloride is completely dissolved. 5.2.5 Dilute the solution (5.2.4) to about 100 mL. Add 5 mL of nickel potassium cyanide solution (4.5) and 50-100 mg of murexamide indicator (4.4). Immediately titrate with EDTA standard titration solution (4.6) until the solution changes from yellow to red to purple. Calculation and description of analysis results The percentage of silver is calculated as follows: I Where: V- Allowable difference V.mi×100 Volume of EDTA standard titration solution consumed by titrating standard sample, mL; Volume of EDTA standard titration solution consumed by titrating sample, mL Mass of pure silver in standard sample Mass of sample, g. The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 2. Table 2 0.50~2.00 >2.00~5.00 >5.00~20.00 >20.00~~10.00wwW.bzxz.Net Additional Notes: GB/T15249.2—94 This standard was jointly proposed by the People's Bank of China Printing Corporation and the State Gold Administration. This standard was drafted by China Gold and Silver Smelter and Changchun Gold Research Institute. The main drafters of this standard are Wang Zisen, Lin Leqin and Bao Zhuling. 74 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.