GB/T 8647.8-1988 Chemical analysis method for nickel - Determination of sulfur content by distillation-oscillographic polarography GB/T8647.8-1988 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Chemical analysis method of nickel
Determination of sulfur content-- Oscillopolarographic method after distillation
Nickel --. Determination of sulfur content-- Oscillopolarographic method after distillation
Nickel --. Determination of sulfur content-- Oscillopolarographic method after distillation This standard applies to the determination of sulfur content in dry nickel. Determination range: 0.0003%~0.050%. UDC 669. 24
GB8647.888
This standard complies with GB1467-78 "General Principles and General Provisions of Chemical Analysis Methods for Metallurgical Products". 1 Method Summary
The sample is dissolved in nitric acid and hydrochloric acid, and the nitric acid is driven out with hydrochloric acid. The sulfur is reduced to hydrogen sulfide with hydroiodic acid-hypophosphorous acid, and absorbed in sodium hydroxide solution under nitrogen carrier, and then determined by oscillographic polarography. 2 Reagents
The water used for preparing solutions and analysis is double distilled water. 2.1 Nitrogen: Purity>99.7%
2.2 Hydrochloric acid: Distill and purify high-grade pure hydrochloric acid through a reagent purification device (3.4), discard the initial 10% (V/V) fraction and the last few milliliters, and collect the remaining fractions in a clean glass reagent bottle. The sulfur content of the refined hydrochloric acid should be less than 0.03m/L2.3 Nitric acid: Distill and purify high-grade pure nitric acid through a reagent purification device (3.4), discard the initial 10% (V/V) fraction and the last few milliliters, and collect the remaining fractions in a clean glass reagent bottle. 2.4 Nitric acid-hydrochloric acid mixed acid: Add 30mL nitric acid (2.3) to 10mL hydrochloric acid (2.2) and mix well. Prepare freshly before use. 2.5 Reducing agent:
2.5.1 Refined hydroiodic acid: Add 20g of sodium hypophosphite to every 1000mL of hydroiodic acid, heat in the reagent purification device (3.4), discard the first section, collect the fraction after the boiling point reaches 125℃ (the last few milliliters are discarded). 2.5.2 Take 200ml hydrochloric acid (superior pure), 300ml hydroiodic acid (2.5.1) and 150ml hypophosphorous acid and place them in the reducing agent purification device (3.3) to mix, heat and control the temperature to keep the reducing agent slightly boiling. Reflux under nitrogen for 5-8h until the sulfur blank value of the reducing agent is less than 3μg/L. After cooling, the reducing agent is stored in a brown bottle. It is valid for two weeks. 2.6 Absorption solution: Prepare 1ma1/L sodium hydroxide, 0.2mol/L hydroxylamine hydrochloride and 0.005% ethylene alcohol solution from the super pure reagent, which is valid for two weeks.
2.7 Sulfur standard solution: Accurately weigh 0.5435g of potassium sulfate (superior grade) that has been dried at 105℃ for 1h, dissolve it in water, transfer it into a 000mL bottle, dilute to the mark, and mix well. This solution contains 100ug sulfur in 1mL. 3 Instruments and equipment
3.1 Linear scanning oscillographic polarograph (with three-electrode system). 3.2 Reduction distillation device (see Figure 1).
China Nonferrous Metals Industry Corporation approved on 1988-01-11 430
implemented on 1989-01-01
GB 8647.8-88
3.3 Reducing agent purification device (see Figure 2)
Nitrogen inlet
GB8647.8-88
Double surface cooler
1-neck bottle
Figure 2 Reducing agent purification device
Sulfurized absorption tube
Thermometer
3.4 ​​Reagent purification device (see Figure 3).
Separation reflux column ~ 50cm long
4 Analysis steps
4.1 Sample quantity
Weigh the sample according to Table 1.
Sulfur content, 8
0.000 10.001
>0. 001 ~0. 005
0. 005 ~ 0. 05
4.2 Sample treatment
1L flask
GB8647.888
Figure 3 Reagent purification device
Sample amount, 8
Nitric acid-hydrochloric acid
Mixed acid (2.4) amount, ml
Condenser ~hicm long
Absorption liquid, mL
Place the sample (4.1) in a 10mL quartz beaker, add 3mL hydrochloric acid (1+3), rinse for 1min, remove the hydrochloric acid, wash with water, and drain the water.
4.3 Air Self-Test
Carry out air self-test with the sample.
4.4 Determination
GB 8647.8-88
4.4.1 Add nitric acid-hydrochloric acid mixture (2.4) to the sample (4.2), heat, evaporate to dryness after the sample is completely dissolved. Add 2ml. hydrochloric acid (2.2), evaporate to dryness, repeat three times, and drive out all the nitric acid. Add 2mL hydrochloric acid (2.2), heat slightly until the salt is completely dissolved. 4.4.2 Transfer the sample (1.4.1) into the main reduction bottle (Figure 1) A, and add 30mL and 5mL of reducing agent (2.5) to the liquid bottle (Figure 1) B and the secondary reduction bottle (Figure 1) C respectively. Control the nitrogen flow rate to about 50mL/min, connect the absorption tube, and fill the tube with absorption liquid (2.6) in advance according to Table 1.
4.4.3 Heat the secondary reduction bottle to keep the reducing agent slightly boiling. 4.4.4 Place the reducing agent from the liquid storage bottle into the main reduction bottle, start the main reduction heater, quickly raise the temperature, make the reducing agent reach boiling within 3 minutes, adjust the temperature, keep the reducing agent slightly boiling, and stop heating after 15 minutes. Stop nitrogen flow after 5 minutes, the ventilation capillary automatically sucks the absorption liquid to a height of 10mm, then pass nitrogen again, repeat 2~~3 times, and remove the absorption tube. 4.4.5 Transfer part of the absorption liquid to the electrolytic cell, select an appropriate sensitivity multiplier (based on the peak current value greater than half of the full scale),
at -0.45V (relative to the saturated glycan electrode) as the starting potential, and record the cathode peak current value after the electrode is inserted into the solution for 1 minute. 4.4.6 Take two sulfur standard solutions (2.7) with sulfur content roughly similar to that of the sample, and measure according to 4.4.2 to 4.4.5. The range between the two standard determination values ​​shall not exceed 10%, and the average value shall be taken as the standard peak current value. 5 Calculation of analysis results
The percentage content is calculated according to the following formula:
Where: mn
Sample weight,;
Sulfur standard,;
1. —-Blank value peak current value;
I——Sample peak current value:
I, Sulfur standard peak current value.
6 Allowable difference
The difference between the analysis results of laboratories shall not be greater than the allowable difference listed in Table 2. Table 2
0. 000 10 -- 0. 000 30
>0.00030~0.00080
20. 000 80~0.002 00Www.bzxZ.net
>0. 002 0~0. 005 0
0. 005 0~0. 015 0
>0. 015 ~~0. 050
Allowance
Additional remarks:
GB8647.8-88
This standard is under the technical jurisdiction of Beijing Research Institute of Mining and Metallurgy. This standard was drafted by Beijing Research Institute of Mining and Metallurgy and Jinchuan Nonferrous Metals Company. This standard was drafted by Beijing Research Institute of Nonferrous Metals. The main drafters of this standard are Jin Jingru and Lin Zhongpeng. 4.35
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