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GB/T 3654.3-2019 English PDF (GBT3654.3-2019)

GB/T 3654.3-2019 English PDF (GBT3654.3-2019)

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GB/T 3654.3-2019: Ferroniobium -- Determination of silicon content -- Gravimetric method

This Part of GB/T 3654 stipulates the determination of silicon content in ferroniobium through gravimetric method. This Part is applicable to the determination of silicon content in ferroniobium; the range of determination (mass fraction): 1.00% ~ 10.00%.
GB/T 3654.3-2019
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 77.100
H 11
Replacing GB/T 3654.3-1983
Ferroniobium - Determination of Silicon Content -
Gravimetric Method
ISSUED ON: JUNE 4, 2019
IMPLEMENTED ON: MAY 1, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the PEOPLE Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative References ... 5
3 Principle ... 5
4 Reagents ... 6
5 Equipment and Materials ... 6
6 Sampling and Sample Preparation ... 6
7 Analytical Procedures ... 7
8 Result Calculation and Expression ... 8
9 Precision ... 9
10 Test Report ... 10
Appendix A (normative) Sample Analysis Result Acceptance Procedure Flow Chart ... 11
Appendix B (informative) Precision Test Data ... 12
Foreword
GB/T 3654 Methods for Chemical Analysis of Ferroniobium is divided into 9 parts: ---GB/T 3654.1 Methods for Chemical Analysis of Ferroniobium - The Paper Chromatographic Gravimetric Method for the Determination of Niobium and Tantalum Content;
---GB/T 3654.2 Ferroniobium - Determination of Copper Content - The
Neocuproine-chloroform Extraction Photometric Method;
---GB/T 3654.3 Ferroniobium - Determination of Silicon Content - Gravimetric Method;
---GB/T 3654.4 Methods for Chemical Analysis of Ferroniobium - The Combustion Gravimetric Method for the Determination of Carbon Content;
---GB/T 3654.5 Methods for Chemical Analysis of Ferroniobium - The
Molybdenum Blue Photometric Method for the Determination of the
Phosphorous Content;
---GB/T 3654.6 Ferroniobium - Determination of Sulfur Content - Combustion- iodate Titrimetric Method, Methylene Blue Photometric Method and Infrared Absorption Method;
---GB/T 3654.8 Ferroniobium - Determination of Titanium Content - Chromotropic Acid Photometric Method;
---GB/T 3654.9 Methods for Chemical Analysis of Ferroniobium - The Thiocyanate Photometric Method for the Determination of Tungsten Content;
---GB/T 3654.10 Methods for Chemical Analysis of Ferroniobium - The EDTA Volumetric Method for the Determination of Aluminum Content.
This is the third part of GB/T 3654.
This Part was drafted in accordance with the rules in GB/T 1.1-2009.
This Part serves as a replacement of GB/T 3654.3-1983 Methods for Chemical Analysis of Ferroniobium - The Gravimetric Method for the Determination of Silicon Content. In comparison with GB/T 3654.3-1983, the main technical changes are as follows:
---Warning content is added (see the main body);
---Normative references are added (see Chapter 2);
Ferroniobium - Determination of Silicon Content -
Gravimetric Method
Warning: personnel using this Part shall have practical experience of working in a regular laboratory. This Part does not point out all the possible safety issues. Users shall undertake the responsibility of adopting proper safety and health measures and guaranteeing the compliance with the conditions stipulated by relevant national laws and regulations.
1 Scope
This Part of GB/T 3654 stipulates the determination of silicon content in ferroniobium through gravimetric method.
This Part is applicable to the determination of silicon content in ferroniobium; the range of determination (mass fraction): 1.00% ~ 10.00%.
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 4010 Ferroalloys Sampling and Preparation of Samples for Chemical Analysis; GB/T 6379.1 Accuracy (trueness and precision) of Measurement Methods and Results - Part 1: General Principles and Definitions;
GB/T 6379.2 Accuracy (trueness and precision) of Measurement Methods and Results - Part 2: Basic Method for the Determination of Repeatability and Reproducibility of a Standard Measurement Method;
GB/T 6682 Water for Analytical Laboratory Use - Specification and Test Methods; GB/T 8170 Rules of Rounding off for Numerical Values and Expression and Judgement of Limiting Values.
3 Principle
Use sodium hydroxide and sodium peroxide to melt and decompose sample. Use 7 Analytical Procedures
7.1 Sample Amount
Weigh-take 0.50 g of sample, accurate to 0.0001 g.
7.2 Times of Determination
In terms of the same sample, at least conduct independent determination twice. 7.3 Blank Test
Conduct blank test along with the sample.
7.4 Determination
7.4.1 Sample decomposition
Place the sample (7.1) in the nickel crucible (5.2); add 2 g of sodium hydroxide (4.1), 4 g of sodium peroxide (4.2), mix them up. On an electric furnace, heat it up, bake it, till it reaches a dry and hard state. Put on the crucible cover; place it into the high- temperature furnace (5.4). From room temperature, slowly heat it up to around 700 ??C. At 700 ??C, continue melting for 15 min ~ 20 min; take it out to cool it down. Use water to wash the bottom of the crucible; place it into a 500 mL beaker, which contains 150 mL of sulfuric acid (4.7) and is covered with a watch glass, to leach the molten block. Wash the crucible and the cover; stir it, till there is no precipitation of hydroxide in the solution.
7.4.2 First dehydration of silicic acid
Place a beaker on an electric heating plate or a low-temperature electric furnace. Conduct cryo-concentration, till it emits sulfuric acid smoke. Then, at a high temperature, heat it up to make the sulfuric acid smoke reflux in the beaker for 15 min ~ 20 min. Then, take it down to slightly cool it down. Slowly add 10 mL of hydrochloric acid (4.3), the, cool it down; add 150 mL of hot water and 5 mL of hydrogen peroxide (4.5), then, evenly stir it. Heat it up, till it nearly reaches boiling; dissolve the precipitated niobium pentoxide hydrate and soluble salts. If the solution is not pellucid, 1 mL ~ 2 mL of hydrogen peroxide (4.5) may be added to dissolve it. Use medium- speed quantitative filter paper, which adds a little amount of paper pulp, to filter it. Use glass rod, which has a rubber head, to wipe the watch glass, the glass road and the inner wall of the beaker. Use hot sulfuric acid washing solution (4.8) to wash it. Then, rinse and precipitate it for 7 times ~ 9 times; transfer the precipitation, along with the filter paper, into the platinum crucible (5.3) for reservation.
7.4.3 Secondary dehydration of silicic acid
Add 5 mL of sulfuric acid (4.6) into the filtrate; place it on the electric heating plate, heat it up, till it emits sulfuric acid smoke for 5 min ~ 10 min. Then, take it down to slightly cool it down. Proceed in accordance with the subsequent procedures in 7.4.2. 7.4.4 Burning precipitation
Place the precipitation, along with the filter paper, into the platinum crucible (7.4.2; 7.4.3). On an electric heating plate, at a low temperature, dry it. At 500 ??C ~ 600 ??C, in the high-temperature furnace (5.4), ash it. Then, continue to raise the temperature to 1,050 ??C; burn for 40 min. Take it out to slightly cool it down. Then, place it in a dryer to cool it down to room temperature, then, weigh it. Repeatedly burn it, till it reaches a constant mass.
Along the inner wall of the crucible, add 4 drops of sulfuric acid (4.6) to wet the dry residue. Add 4 mL ~ 5 mL of hydrofluoric acid (4.4). Place it on the electric heating plate, then, heat it up, evaporate it, till it emits sulfuric acid smoke. Slightly cool it down, then, along the inner wall of the crucible, add 4 mL of hydrofluoric acid (4.4). Continue to heat it up, evaporate it, till it emits all the sulfuric acid smoke. Place the crucible in 1,050 ??C high-temperature furnace (5.4), burn for 20 min. Then, take it out to slightly cool it down. Place it in a dryer, cool it down to room temperature, then, weigh it. Repeatedly burn it, till it reaches a constant mass.
8 Result Calculation and Expression
8.1 Result Calculation
In accordance with Formula (1), calculate the mass fraction of silicon in the sample, expressed in (%):
Where,
wSi---mass fraction of silicon, expressed in (%);
m1---the mass of precipitation and platinum crucible before hydrofluoric acid treatment, expressed in (g);
m2---the mass of residue and platinum crucible after hydrofluoric acid treatment, expressed in (g);
m3---the mass of precipitation and crucible in the blank test before hydrofluoric acid treatment, expressed in (g);
m4---the mass of precipitation and crucible in the blank test after hydrofluoric acid treatment, expressed in (g);

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