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GB/T 31924-2015 English PDF (GBT31924-2015)

GB/T 31924-2015 English PDF (GBT31924-2015)

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GB/T 31924-2015: Nickel pig iron -- Determination of nickel content -- Dimethylglyoxime gravimetric method

This Standard specifies the method of determining nickel content in nickel-containing pig iron through the dimethylglyoxime gravimetric method. This Standard is applicable to the determination of nickel content in nickel-containing pig iron. The range of determination (mass fraction) is: 2.00% ~ 20.00%.
GB/T 31924-2015
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 77.100
H 11
Nickel Pig Iron - Determination of Nickel Content -
Dimethylglyoxime Gravimetric Method
ISSUED ON: SEPTEMBER 11, 2015
IMPLEMENTED ON: JUNE 1, 2016
Issued by: General Administration of Quality Supervision, Inspection and Quarantine;
Standardization Administration of the PEOPLE Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Principle ... 4
4 Reagents and Materials ... 4
5 Sample Collection and Preparation ... 5
6 Instruments ... 5
7 Analytical Procedures ... 6
8 Result Calculation ... 8
9 Allowable Difference ... 8
10 Test Report ... 9
Nickel Pig Iron - Determination of Nickel Content -
Dimethylglyoxime Gravimetric Method
Warning---personnel adopting this Standard shall have practical experience in formal laboratory work. This Standard does not point out all safety issues. The user is responsible for taking appropriate safety and health measures and ensuring the compliance with the conditions stipulated by relevant national laws and regulations.
1 Scope
This Standard specifies the method of determining nickel content in nickel-containing pig iron through the dimethylglyoxime gravimetric method.
This Standard is applicable to the determination of nickel content in nickel-containing pig iron. The range of determination (mass fraction) is: 2.00% ~ 20.00%. 2 Normative References
The following documents are indispensable to the application of this document. In terms of references with a specified date, only versions with a specified date are applicable to this document. In terms of references without a specified date, the latest version (including all the modifications) is applicable to this document. GB/T 6682 Water for Analytical Laboratory Use - Specification and Test Methods GB/T 11415-1989 Laboratory Sintered (fritted) Filters - Porosity Grading, Classification and Designation
GB/T 28296 Pig Iron Containing Nickel
3 Principle
The specimen is decomposed with hydrochloric acid and nitric acid. Perchloric acid emits smoke to drive out fluorine and silicon. In the ammoniacal medium of tartrate, use dimethylglyoxime to precipitate nickel. The precipitate is dried at 145 ??C to a constant weight. Then, calculate the nickel content in the specimen.
4 Reagents and Materials
Unless it is otherwise specified, only reagents that are confirmed to be analytically pure and distilled water or Grade-3 water that complies with the stipulations of GB/T 6682 are used in the analysis.
4.1 Mixed solvent, boric acid : anhydrous potassium carbonate : anhydrous sodium carbonate = 1 : 1 : 1.
4.2 Ammonium fluoride, solid.
4.3 Nitric acid, ??? 1.42 g/mL.
4.4 Hydrochloric acid, ??? 1.19 g/mL.
4.5 Perchloric acid, ??? 1.67 g/mL.
4.6 Ammonia water, ??? 0.925 g/mL.
4.7 Hydrochloric acid, 1 + 1.
4.8 Hydrochloric acid, 5 + 95.
4.9 Tartaric acid solution, 500 g/L.
4.10 Dimethylglyoxime, 10 g/L, ethanol solution.
5 Sample Collection and Preparation
In accordance with the stipulations of GB/T 28296, conduct sample collection and preparation. The grain size of the ground specimen shall be less than 0.125 mm; the grain size of the drilled specimen shall be between 0.154 mm ~ 1.68 mm. 6 Instruments
Adopt normal laboratory instruments, and
6.1 Filter crucible, sintered porous glass, with a pore diameter of 10 ??m ~ 20 ??m, in line with P16 specification specified in GB/T 11415-1989 or commercially available G3 and G4 crucibles.
6.2 The suction filtration device is shown in Figure 1.
7.3.1 Weighing of empty crucible
Place a mixture of 20 mL of hot hydrochloric acid (see 4.4), 10 mL of nitric acid (see 4.3) and 30 mL of water into the filter crucible (see 6.1) for filtration, then, use warm water to wash the acidic substances on the crucible. Place the crucible in an oven at 145 ??C to dry for 2 h. In a desiccator, cool it down to room temperature, then, quickly weigh it.
7.3.2 Dissolution of specimen
7.3.2.1 Place the specimen in a 400 mL beaker; add 10 mL of water; add 0.5 g ~ 1 g of ammonium fluoride (see 4.2). Let it stand for 2 min. Then, add 5 mL of hydrochloric acid (see 4.4) and let it stand for 1 min. Add 20 mL of nitric acid (see 4.3); maintain the volume and heat it up at a low temperature, until the sample no longer dissolves [if the sample is insoluble, add another 0.5 g ~ 1 g of ammonium fluoride (see 4.2)]; add 10 mL of perchloric acid (see 4.5); continue to heat it up, until it emits perchloric acid smoke and the volume reaches 2 mL ~ 3 mL; add 40 mL of water to boil and dissolve the salts. If the specimen is completely dissolved, proceed in accordance with 7.3.3; if the sample has a small amount of residue, proceed in accordance with 7.3.2.2. 7.3.2.2 If there is a small amount of residue, filter it; collect the filtrate in a 500 mL beaker; use hot water to wash it, until it is acid-free; this is the mother solution. Place the residue and filter paper in a platinum crucible for low-temperature ashing. After ashing, add 2 g ~ 3 g of the mixed solvent (see 4.1); send it into a 900 ??C high- temperature furnace to melt for 10 min, until it is limpid, then, take it out, shake it and cool down to room temperature. Use a small amount of water to leach it in the original beaker; use water to wash the platinum crucible; add 10 mL of hydrochloric acid (see 4.7) to acidify it and combine it with the mother solution.
7.3.3 Treatment of test solution
Add 10 mL of tartaric acid solution (see 4.9) to the test solution (see 7.3.2); dilute the solution to 250 mL. Under constant stirring, use ammonia water (see 4.6) to adjust to pH 4.5; use hot water at 60 ??C ~ 80 ??C to dilute to 300 mL.
7.3.4 Precipitated nickel
While stirring, add dimethylglyoxime (see 4.10) to the test solution (see 7.3.3). For every 1 mg of nickel, 0.4 mL of dimethylglyoxime (see 4.10) needs to be added, and an excess of 20 mL (the volume shall not exceed 1/3 of the volume of the test solution, so as not to dissolve part of the precipitate in ethanol). Then, while stirring, use ammonia water (see 4.6) to slowly adjust the solution to pH 8 ~ 9. After thoroughly stirring it, let it stand for 30 min to coagulate the precipitate.
7.3.5 Filtration, drying and weighing
Transfer the precipitate (see 7.3.4) to a dry filter crucible that has reached a constant

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