GB/T 15072.3-1994 Chemical analysis methods for precious metals and their alloys - Determination of platinum content in gold, platinum and palladium alloys
Some standard content:
National Standard of the People's Republic of China
Chemical analysis methods for precious metals and their alloys
Gold, platinum and palladium alloys—Determination of platinum content1 Subject content and scope of applicationwwW.bzxz.Net
This standard specifies the method for determining the platinum content in gold, platinum and palladium alloys. GB/T15072.394
This standard is applicable to the determination of platinum content in PtIr10, PtIr17.5, PtIr25, PtW8, PtW8.5, PdAgCuAuPiZn30-14-10-10-1, AuAgPt25-6 alloys. Determination range: 5%~95%. 2 Reference standards
GB1.4 Guidelines for standardization work Provisions for the preparation of chemical analysis methods GR1467 General principles and general provisions for chemical analysis methods for metallurgical products GB/T15072.6 Chemical analysis methods for precious metals and their alloys Determination of iridium content in platinum and palladium alloys 3 Method summary
Gold, palladium alloy and platinum-tungsten alloy samples are dissolved with mixed acid. Platinum-iridium alloy samples are dissolved with hydrochloric acid-hydrogen peroxide. Platinum (V) is reduced to platinum (I) with cuprous chloride in dilute hydrochloric acid solution and titrated with potassium permanganate standard titration solution. The endpoint is indicated by the amperometric method, and the selected potential is +0.65V.
4 Reagents
Hydrochloric acid ((p1.19 g/mL).
4.2 Hydrogen peroxide (30%).
4.3 Mixed acid: Mix three unit volumes of hydrochloric acid with one unit volume of nitric acid (pl.42g/ml.). Prepare it when needed. 4.4 Mixed acid: Mix thirty unit volumes of hydrochloric acid with one unit volume of nitric acid (pl.42g/mL). Prepare it when needed. 4.5 Sulfuric acid (1+3).
4.6 Sodium chloride solution (50g/L).
4.7 Cuprous chloride solution: Weigh 3.0g of cuprous chloride and place it in a 100mL volumetric Add 30ml of hydrochloric acid to the bottle, dilute to the mark with water, and mix well. Prepare on the same day.
4.8 Platinum standard solution: weigh 0.23g of metal platinum (99.99%), accurate to 0.0001g. Add 40ml of mixed acid (4.3) to a 100ml beaker, heat at low temperature until completely dissolved, and rinse the surface III and the wall of the beaker. Add 5ml of sodium chloride solution and evaporate at low temperature until almost dry. Add 3ml of hydrochloric acid and evaporate until almost dry, repeat twice. Add 10mL of hydrochloric acid, transfer to a 100mL volumetric flask, dilute to the mark with water, and mix well. This solution contains 2.3 mg of platinum in 1ml.
4.9 Potassium permanganate standard titration solution Lc (KMnO,) = 0.0044mol/L) 4.9.1 Preparation: Weigh 0.7g of potassium permanganate, dissolve in 5L of water, boil for 1.5h, and let stand overnight. Filter with a No. 3 glass sand funnel. Dilute to 5 with water, mix well, store in a brown bottle, and store in a dark place. 4.9.2 Calibration: Calibration is carried out in parallel with the determination of the sample. Take three portions of 10.00mL of the platinum standard solution and place them in 100ml beakers respectively, add 0.5mL of sodium chloride solution, and steam at low temperature until the volume is close to the bottom. Add 2ml of hydrochloric acid, 8mL of cuprous chloride solution, add water to a volume of 40mL, heat and boil for 2min, remove, and rinse the watch glass and the wall of the cup with water. Add 1ml of sulfuric acid, blow on the blowing device (see figure) for 15min, remove, and rinse the surface blood and the wall of the cup. Blow for another 15min to rinse the surface and the wall of the cup.
Insert a platinum indicator electrode and a saturated calomel electrode into the above test solution, select a potential of +0.65V, start the electromagnetic stirrer, and titrate with a potassium permanganate standard titration solution. Plot the volume of the potassium permanganate standard titration solution against the corresponding current value, extrapolate the two straight lines, and the volume corresponding to the intersection is the end point of the titration. The range of the volume of the potassium permanganate standard titration solution consumed in the parallel calibration should not exceed 0.10mL. Take the average value:
Calculate the actual concentration of the potassium permanganate standard titration solution according to formula (1): m
c = V. × 0. 487 7
Wherein: (--actual concentration of potassium permanganate standard titration solution, mol/L; m---mass of platinum in the transferred platinum standard solution, g, V-volume of potassium permanganate standard titration solution consumed in calibration, mL,. (1)
0.4877-=mass of platinum in grams equivalent to 1.00ml potassium permanganate standard titration solution [c(KMnO)=1.000mol/1.].
5 Apparatus
5.1 Current titration apparatus
5.1.1 Ordinary polarograph: galvanometer sensitivity 1×10-8A/mm/M. 5.1.2 Magnetic heating stirrer.
5.1.3 Iron core stirrer Stirring rod.
5.1.4 Platinum wire indicator electrode: ×L, mm, 1×2. 5.1.5 Saturated potassium chloride agar salt bridge.
5.1.6 Saturated potassium chloride calomel electrode.
5.2 Blowing device, as shown in the figure:
6 Test sample
GB/T15072.3—94
Schematic diagram of blowing device
--Oil-free gas compressor; 2-
-Two-way glass piston; 3 Safety bottle; 4-Washing bottle (500mL); 5-Potassium dichromate-sulfuric acid washing liquid; 6-Air flow meter (10L/min); 7-Beaker (100ml.); 8-Hole surface III; 9-Glass tube (20 mm) sample into crumbs, and finally use acetone to remove oil, wash, dry and mix. 7 Analysis steps
7.1 Test sample
Weigh the sample according to Table 1, accurate to 0.0001g. Table 1
Platinum content, %
5. 00~12. 00
>12. 00~74. 00
>74.00~76.00
≥76. 00~81,00
≥81. 00 ~83. 00
>83.00~89.00
≥89. 00~95.00
Carry out two independent measurements and take the average value. Sample amount, g
7.2 Determination
7.2.1 Dissolution
GB/T 15072.3--94
7.2.1.1 Place the platinum-tungsten alloy sample in a 100ml beaker, add 40ml of mixed acid (4.3), cover the top, heat at low temperature until the sample is completely dissolved, and rinse the surface blood and the wall of the beaker with water. Add 0.5mL of sodium chloride solution and evaporate to nearly dryness. Add 3ml of hydrochloric acid and evaporate to nearly ten, repeat twice. Add 10ml of hydrochloric acid, transfer to a 100ml volumetric flask, dilute to scale with water, and mix. Transfer 10.00ml of the solution to a 100ml beaker, add 0.5ml of sodium chloride solution, and evaporate to dryness at low temperature. 7.2.1.2 Dissolve the platinum-iridium alloy sample according to Appendix A (Supplement) of GB/T15072.6: transfer the test solution to a 100ml volumetric flask, add 10mL of hydrochloric acid, cool to room temperature, and dilute to scale with water. Mix. Transfer 10.00ml of the test solution to a 100mL beaker, add 0.5ml of sodium chloride solution, and evaporate to dryness at low temperature.
7.2.1.3 Place the gold and palladium alloy samples in a 100mL beaker, add 40mL of mixed acid (4.4), cover the surface III, heat at low temperature until the sample is completely dissolved, and rinse the surface III and the wall of the cup with water. Add 0.5ml of sodium chloride solution and evaporate to nearly dryness. Add 3ml of hydrochloric acid and evaporate to nearly +, repeat times.
7.2.2 Treatment of residues
7.2.2.1 Add 2ml of hydrochloric acid and 8ml of cuprous chloride solution to the gold and palladium alloy residues (7.2.1.3), boil for 2min, remove, rinse the surface blood and the wall of the cup with water, control the total volume to about 40ml, boil for another 2min, remove, rinse the surface twist and the wall of the cup. Add 1ml sulfuric acid, cover the perforated surface III with a blower for 15 minutes, remove, rinse the surface dish and the cup wall, and blow for another 15 minutes. Remove. Rinse the surface III and the cup wall. Filter with a No. 3 glass sand funnel, and rinse the cup wall and funnel with water five times each. 7.2.2.2 Treatment of platinum-tungsten alloy residue (7.2.1.1) and platinum-iridium alloy residue (7.2.1.2) shall be carried out in accordance with 7.2.2.1, but without filtering. 7.2.3 Titration
7.2.3.1 Insert a platinum indicator electrode, a ground electrode and a galvanneal electrode into the test solution (the platinum-tungsten alloy test solution in 7.2.2.1 or 7.2.2.2), and select a potential of -10.65V, start the electromagnetic stirrer, and titrate with potassium permanganate standard titration solution. Plot the volume of potassium permanganate standard titration solution against the corresponding current value, extrapolate the two straight lines, and the volume corresponding to the intersection is the end point of the titration. 7.2.3.2F Add 50.00mL of potassium permanganate standard titration solution to the platinum-iridium alloy test solution (7.2.2.2), stir evenly, and heat to 70 (the following is carried out according to 7.2 and 3.1.
8 Expression of analysis results
Calculate the percentage of platinum according to formula (2):
P(%) = ×VX9. 4872 × 100
m.× V.
Wherein: c---actual concentration of potassium permanganate standard titration solution, mol/LV,--volume of potassium permanganate standard titration solution consumed in titration of test solution, mLV.total volume of test solution, mL;
V..volume of test solution taken, ml.;
m.---mass of test material, g
(2)
0.4877--with 1.00ml potassium permanganate standard titration solution [c( KMn0,）--1.000mol/LJ equivalent to the mass of platinum in grams.
The result should be expressed to two decimal places.
9Tolerance
The difference between the analysis results of laboratories should not be greater than the tolerance listed in Table 2. 70
Additional remarks:
Platinum content
5.00~15.00
>15.00~70.00
>70. 00 ~ 90. 00
>90.00~95.00
GB/T15072.3-94
This standard is proposed by China Nonferrous Metals Industry Corporation. This standard is drafted by Kunming Precious Metals Research Institute. This standard is drafted by Kunming Precious Metals Research Institute. The main drafters of this standard are Zhao Duozhong, Zhao Lisha and Qin Yan. Allowable difference
From the date of implementation of this standard, the former Metallurgical Department Standard YB946 (Au-9)-78 "Chemical Analysis Methods for Gold, Silver and Platinum Alloys" will be invalid. 71
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