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GB/T 8454-2020 English PDF (GBT8454-2020)

GB/T 8454-2020 English PDF (GBT8454-2020)

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GB/T 8454-2020: Reduced ilmenite powder for welding rob--Determination of ferrous iron content--Potassium dichromate titrimetric method
This Standard specifies to use potassium dichromate titrimetric method to determine ferrous iron content in reduced ilmenite powder for welding rob. This Standard is applicable to determination of ferrous iron content in reduced ilmenite powder for welding rob. Range for determination (mass fraction): 1.00%~10.00%.
GB/T 8454-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 73.060.10
D 31
Replacing GB/T 8454-1987
Reduced ilmenite powder for welding rob -
Determination of ferrous iron content - Potassium
dichromate titrimetric method
ISSUED ON: JUNE 02, 2020
IMPLEMENTED ON: DECEMBER 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the People's Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Principle ... 6
4 Reagents ... 6
5 Equipment and materials ... 7
6 Sampling and sample preparation ... 7
7 Analysis steps ... 8
8 Calculation of analysis results ... 9
9 Processing of analysis results ... 11
10 Test report ... 13
Annex A (normative) Acceptance procedures for specimen analysis results . 14 Annex B (informative) Additional information for common precision test ... 15 Reduced ilmenite powder for welding rob -
Determination of ferrous iron content - Potassium
dichromate titrimetric method
WARNING - Personnel using this Standard shall have practical experience in formal laboratory work. This Standard does not point out all possible safety issues. The user is responsible for taking appropriate safety and health measures and ensuring compliance with the conditions stipulated
by the relevant national standards and regulations.
1 Scope
This Standard specifies to use potassium dichromate titrimetric method to determine ferrous iron content in reduced ilmenite powder for welding rob. This Standard is applicable to determination of ferrous iron content in reduced ilmenite powder for welding rob. Range for determination (mass fraction): 1.00%~10.00%.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
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 6730.1, Iron ores - Preparation of pre-dried test samples for chemical analysis
GB/T 8170, Rules of rounding off for numerical values and expression and
4.10 Sulfuric acid-phosphoric acid mixed acid, 2+3+5.
4.11 Saturated boric acid solution.
4.12 Ferric chloride solution, 100g/L.
Weigh 100.0g of iron trichloride (FeCl3 • 6H2O) to dissolve in 1000mL of water. Mix well. If the solution is turbid, it shall be filtered before use.
4.13 Ferrous ammonium sulfate solution, about 0.03mol/L.
Weigh 11.8g of ferrous ammonium sulfate [(NH3)2Fe(SO4)2 • 6H2O] to dissolve in 500mL of sulfuric acid (5+95). Use sulfuric acid (5+95) to transfer and dilute to 1000mL. Mix well.
4.14 Potassium dichromate standard titration solution, c(1/6K2Cr2O7) =
0.05000mol/L.
Weigh 2.4518g of the reference reagent potassium dichromate, which has been dried at 150°C for 1h and cooled to room temperature in a desiccator. Dissolve in 500mL of water. Transfer to a 1000mL volumetric flask. Use water to dilute to the scale. Mix well.
4.15 Sodium diphenylamine sulfonate indicator solution, 2g/L.
Weigh 0.20g of sodium diphenylamine sulfonate to dissolve in 100mLof water. Mix well. If the solution is turbid, it shall be filtered before use.
5 Equipment and materials
Unless otherwise specified, use normal laboratory equipment. Burettes, single- marked volumetric flasks and single-marked pipettes shall meet the
requirements of GB/T 12805, GB/T 12806 and GB/T 12808 respectively.
5.1 Metal iron core stirrer (non-magnetic), covered with PTFE plastic.
5.2 Adjustable speed magnetic stirrer.
5.3 Non-magnetic sample spoon.
6 Sampling and sample preparation
6.1 Laboratory specimen
Conduct sampling and sample preparation according to GB/T 10322.1. The
particle size of the laboratory specimen for analysis shall be less than 74μm. standard titration solution consumed, V2. Add 10.00mL of ferrous ammonium sulfate solution to the solution again (see 4.13). Use potassium dichromate standard titration solution (see 4.14) to titrate till stable purple. Write down the titrated volume V3. (V2-V3) is the blank of the total amount of ferrous iron and metallic iron.
7.4 Determination of metallic iron
7.4.1 Weigh 0.50g of sample, to the nearest of 0.0001g. Place in a dry 150mL Erlenmeyer flask. Add 30mL of ferric chloride solution (see 4.12). Add the magnetic core. Plug the rubber stopper. Stir on the electromagnetic stirrer for 60min.
7.4.2 Remove. Use medium speed filter paper to filter into a 250mL volumetric flask. Wash the conical flask 5 times and filter paper 5 times. Dilute to the scale. Mix well. Pipette 50.00mL of solution into a 300mL Erlenmeyer flask.
7.4.3 Add 15mL of sulfuric acid-phosphoric acid mixed acid (see 4.10) to the solution obtained in 7.4.2. Add 3 drops of sodium diphenylamine sulfonate indicator solution (see 4.15). Use potassium dichromate standard titration solution (see 4.14) to titrate till stable purple as the end point. Write down the volume of potassium dichromate standard titration solution consumed V4. 7.4.4 Into the blank solution accompanying with the sample, accurately add 10.00mL of ferrous ammonium sulfate solution (see 4.13), 15mL of sulfuric acid- phosphoric acid mixed acid (see 4.10), and 3 drops of sodium diphenylamine sulfonate indicator solution (see 4.15). Use potassium dichromate standard titration solution (see 4.14) to titrate till stable purple. Write down the volume of potassium dichromate standard titration solution consumed V5. Add 10.00mL of ferrous ammonium sulfate solution to the solution again (see 4.13). Use potassium dichromate standard titration solution (see 4.14) to titrate till stable purple. Write down the titrated volume V6. (V5-V6) is the blank of metal iron. 8 Calculation of analysis results
8.1 Calculate the mass fraction (wA) of the total amount of metallic iron and ferrous iron in the sample according to formula (1). The value is expressed as a percentage (%).
Where,
c - Concentration of potassium dichromate standard titration solution, in moles 9.4 Acceptance of analysis values
The acceptance of analysis values is verified using certified reference materials (CRM) or standard samples (RM). Compare the final laboratory results with the standard value Ac. If
a) , then there is no significant difference between the
reported result and the standard value;
b) , then there is a significant difference between the reported
result and the standard value.
Where,
µc - CRM or RM measured value;
Ac - CRM or RM standard value;
C - Its value depends on the type of CRM/RM used.
The C value of the certification standard sample (CRM) or standard sample (RM) determined by multiple laboratories is calculated according to formula (5):
Where,
R - Inter-laboratory reproducibility limit;
r - Repeatability limit in the laboratory;
n - Number of repeated determinations of the standard sample;
u - Uncertainty of CRM/RM sample standard value.
9.5 Calculation of final result
The final result is the arithmetic mean of the acceptable values of the specimen, or the value measured according to the operation specified in Annex A. The analysis results are revised according to GB/T 8170. The analysis result keeps two decimal places.
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