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GB/T 22660.3-2008 English PDF (GBT22660.3-2008)

GB/T 22660.3-2008 English PDF (GBT22660.3-2008)

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GB/T 22660.3-2008: Chemical analysis methods of lithium fluoride -- Part 3: Determination of fluoride content -- Distillation-thorium nitrate titration volumetric method

This Part of GB/T 22660 specifies the method for the determination of fluorine content in lithium fluoride. This Part applies to the determination of fluorine content in lithium fluoride. The determination range is 60~75%.
GB/T 22660.3-2008
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 77.120
H 60
Chemical analysis methods of lithium fluoride - Part 3:
Determination of fluoride content - Distillation-thorium
nitrate titration volumetric method
ISSUED ON: DECEMBER 29, 2008
IMPLEMENTED ON: NOVEMBER 01, 2009
Issued by: General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China;
Standardization Administration of the People's Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Method summary ... 4
4 Reagents ... 4
5 Instruments and equipment ... 5
6 Specimen ... 6
7 Analysis steps ... 6
8 Calculation of analysis result ... 7
9 Precision ... 8
10 Quality assurance and control ... 8
Chemical analysis methods of lithium fluoride - Part 3:
Determination of fluoride content - Distillation-thorium
nitrate titration volumetric method
1 Scope
This Part of GB/T 22660 specifies the method for the determination of fluorine content in lithium fluoride.
This Part applies to the determination of fluorine content in lithium fluoride. The determination range is 60~75%.
2 Normative references
The provisions in following documents become the provisions of this Part of GB/T 22660 through reference in this Part. For dated references, the subsequent amendments (excluding corrigendum) or revisions do not apply to this Part, however, parties who reach an agreement based on this Standard are encouraged to study if the latest versions of these documents are applicable. For undated references, the latest edition of the referenced document applies.
GB/T 22660.1-2008, Chemical analysis methods of lithium fluoride - Part 1: Preparation and storage of test samples
3 Method summary
The test material is directly dissolved in water under acidic conditions. After separation of fluorine by sulfuric acid-steam distillation, use sodium alizarin sulfonate-methylene blue as indicator. Use thorium nitrate solution to titrate.
4 Reagents
4.1 Hydrochloric acid (about 0.06mol/L).
4.2 Sodium hydroxide solution (20g/L).
4.3 Sulfuric acid (2+1).
4.4 Sodium fluoride (baseline).
5.3 Stream flow adjusting tube: The exposed end is covered with a rubber tube with a spring clip.
5.4 Safety tube: 1m long.
5.5 Distiller: Blown in borate glass. Ground joint. Consist of the following parts. 5.5.1 Distillation flask: The volume is 250mL. The central neck diameter is 36mm. The side neck diameter is 20mm. The length is 275mm. The distance between the two diameters is 65mm.
5.5.2 Distillation column: The distance from the first point group to the last point group of the column is 120mm. There are eleven point groups in total. The three points with a distance of 12mm are distributed at an interval of 120??C on the circumference. 5.6 Thermometer sheath.
5.7 Thermometer: The range is 0???~200???. The length is 250mm.
5.8 Dropping funnel: The volume is 100mL.
5.9 Serpentine condenser: 400mm long.
5.10 Electric heater: The temperature can be controlled at 150?????1???.
5.11 pH Meter: Equipped with glass electrodes.
5.12 Borosilicate glass conical beaker: 250mL.
6 Specimen
The specimen shall meet the requirements of 3.3 in GB/T 22660.1-2008.
7 Analysis steps
7.1 Test material
Weigh 0.2g of specimen (6), accurate to 0.0001g.
7.2 Number of determinations
Perform two determinations independently. Take the average.
7.3 Blank test
Conduct a blank test with the test material (7.1).
7.4 Determination
7.4.1 Weigh 0.2g of test material (7.1), accurate to 0.0001g. Use cold water to directly wash into the distillation flask (5.5.1) that has been filled with several glass balls (2mm to 3mm in diameter). Place the 500mL volumetric flask under the condenser (5.9) to collect the distilled solution. Connect the distillation flask (5.5.1) and the serpentine condenser (5.9). Start passing the cooling water. Cap the distillation flask. Add 50mL of sulfuric acid (4.3) through the dropping funnel (5.8). Simultaneously heat the steam generator (5.1) already filled with two-thirds of the water and a few small pieces of pumice. The steam adjustment pipe (5.3) is open before the water boils. Heat the distillation flask (5.5.1) to 150??C with the electric heater (5.10). Adjust the steam flow with the help of the spring clips on the tube. Steam is passed through the hyperbolic conduit (5.2) at a flow rate of 250g/h~300g/h. Maintain the temperature of the solution in the distillation flask (5.5.1) at 150??C ?? 1??C. Make about 400mL of distillate collected in about 90min. Stop distillation. Wash the condenser with water. Dilute the solution in collection bottle to volume. Mix well.
7.4.2 Pipette 50.0mL of the solution (7.4.1) into the beaker (5.12). Add 50.0mL of water and 0.5mL of sodium alizarin sulfonate solution (4.7). Use sodium hydroxide solution (4.2) to adjust until the solution is pink. Under the indication of pH meter (5.11), add hydrochloric acid (4.1) dropwise to adjust the pH between 4.9~5.2 (the solution is yellow). After adding 3mL of sodium alizarin sulfonate solution (4.7), then use buffer solution (4.5) to adjust the pH to 3.4??0.1 (about 1mL of buffer solution). Add 0.5mL of methylene blue solution (4.8) to make the solution green. Use thorium nitrate standard solution (4.6) to titrate until the blue-violet color appears as the end point. 8 Calculation of analysis result
Calculate the mass fraction (%) of fluorine according to formula (2):
Where,
c - The actual concentration of the standard titration solution of thorium nitrate, in milligrams per milliliter (mg/mL);
V3 - The volume of thorium nitrate standard solution consumed when titrating the sample solution, in milliliters (mL);
V4 - The volume of thorium nitrate standard solution consumed when titrating the blank test solution, in milliliters (mL);
m0 - The mass of test material, in milligrams (mg).

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