GB/T 5686.5-2008 English PDF (GBT5686.5-2008)

This part specifies the infrared absorption method, gasometric method, gravimetric method, coulometric method to determine the carbon content of ferromanganese-silicon, ferromanganese, blast furnace ferromanganese, nitrogen-bearing ferromanganese, manganese metal, electrolytic manganese metal.

GB/T 5686.5-2008
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.100
H 11
Replacing GB/T 5686.5 ~ 5686.6-1988, GB/T 7730.5-2000
GB/T 7730.6 ~ 7730.7-1988, GB/T 8654.8-1988
Ferromanganese, ferromanganese-silicon, nitrogen-
bearing ferromanganese and manganese metal -
Determination of carbon content - The infrared
absorption method, the gasometric method, the
gravimetric and the coulometric method
ISSUED ON: MAY 13, 2008
IMPLEMENTED ON: NOVEMBER 01, 2008
Issued by: General Administration of Quality Supervision Inspection and Quarantine of PRC;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 6
3 Method 1: Infrared absorption method ... 6
4 Method 2: Gasometric method ... 10
5 Method 3: Gravimetric method ... 14
6 Method 4: Coulomb method ... 19
7 Test report ... 23
Ferromanganese, ferromanganese-silicon, nitrogen-
bearing ferromanganese and manganese metal -
Determination of carbon content - The infrared
absorption method, the gasometric method, the
gravimetric and the coulometric method
Warning: The personnel using this part shall have practical experience in formal laboratory work. This part 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
relevant national laws and regulations.
1 Scope
This part specifies the infrared absorption method, gasometric method,
gravimetric method, coulometric method to determine the carbon content of ferromanganese-silicon, ferromanganese, blast furnace ferromanganese,
nitrogen-bearing ferromanganese, manganese metal, electrolytic manganese metal.
This part applies to the determination of carbon content in ferromanganese- silicon, ferromanganese, blast furnace ferromanganese, nitrogen-bearing ferromanganese, manganese metal, electrolytic manganese metal. The
infrared absorption method is suitable for the determination of the carbon content (mass fraction) of 0.01% ~ 10.00% in ferromanganese-silicon,
ferromanganese (including blast furnace ferromanganese), nitrogen-bearing ferromanganese, manganese metal; electrolytic manganese metal. The
gasometric method is suitable for the determination of the carbon content (mass fraction) of 0.40% ~ 5.00% in ferromanganese-silicon and ferromanganese (including blast furnace ferromanganese). The gravimetric method is applicable to the determination of ferromanganese (including blast furnace
ferromanganese). The determination of the carbon content (mass fraction) of 4.00% ~ 8.00%. The coulometric method is suitable for the determination of the carbon content (mass fraction) of 0.010% ~ 0.400% in manganese and
electrolytic manganese metal.
2 Normative references
The provisions in following documents become the provisions of this part through reference in this part. For the dated references, the subsequent amendments (excluding corrections) or revisions do not apply to this part; however, parties who reach an agreement based on this part 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 4010 Ferroalloys - Sampling and preparation of samples for chemical analysis
3 Method 1: Infrared absorption method
3.1 Principle
The sample is heated and burned in an oxygen stream in a high-frequency induction furnace. The carbon dioxide generated is carried by the oxygen to the measuring chamber of the infrared analyzer. The carbon dioxide absorbs
infrared energy of a certain wavelength; its absorption energy is proportional to its concentration. According to the change of energy received by the detector, the carbon can be measured.
3.2 Reagents and materials
3.2.1 Acetone, the mass fraction of carbon residue after evaporation is less than 0.0005%.
3.2.2 Magnesium perchlorate, anhydrous, granular.
3.2.3 Caustic soda asbestos, granular.
3.2.4 Glass wool.
3.2.5 Tungsten particles, the mass fraction of carbon is less than 0.002%; the particle size is 0.8 mm ~ 1.4 mm.
3.2.6 Tin particles, the mass fraction of carbon is less than 0.002%; the particle size is 0.4 mm ~ 0.8 mm. If necessary, use acetone (3.2.1) to clean the surface and dry it at room temperature.
3.2.7 Pure iron, the mass fraction of carbon is less than 0.002%; the particle size is 0.8 mm ~ 1.68 mm.
3.2.8 Oxygen, the purity is greater than 99.95%; if other grades of oxygen can obtain a low and consistent blank, it can also be used.
Weigh 0.400 g of pure iron (3.2.7) [ferromanganese, nitrogen-bearing
ferromanganese and manganese metal are not weighed] and place it in a
crucible (3.2.10) which contains 0.300 g of tin particles (3.2.6) in advance. Cover 1.500 g of tungsten particles (3.2.5) [cover 1.800 g of tungsten particles (3.2.5) for ferromanganese, nitrogen-bearing ferromanganese and manganese metal]. Follow 3.5.5 to perform measurement. Repeat sufficient number of measurements. Record the smallest, relatively stable and consistent three readings. Calculate the average value and enter it into the instrument. The instrument will automatically deduct the blank value when measuring the specimen.
3.5.3 Preparation for analysis
Debug and check the instrument; make the instrument in a normal and stable state; select the best analysis conditions.
3.5.4 Calibration test
According to the carbon content of the specimen to be tested, select the corresponding range and channel; select three certified standard samples of the same type (the carbon content of the specimen to be tested shall fall within the range of carbon content of the selected three certified standard samples) to make calibration in sequence, to confirm the linearity of the system. The fluctuations in the results of the certified standard samples measured after calibration shall be within the allowable error range.
3.5.5 Determination
3.5.5.1 Applicable to ferromanganese-silicon: Weigh an appropriate amount (Table 1) of the sample and place it in a crucible (3.2.10) pre-filled with 0.300 g of tin pellets (3.2.6). Evenly cover 0.400 g of pure iron (3.2.7) and 1.500 g of tungsten particles (3.2.5). Make analysis and determination. Analyze and read the results.
3.5.5.2 Applicable to ferromanganese, nitrogen-bearing ferromanganese,
manganese metal: Weigh an appropriate amount (Table 1) of the sample and place it in a crucible (3.2.10) pre-filled with 0.300 g of tin particles (3.2.6). Cover 1.800 g of tungsten particles (3.2.5) uniformly in sequence. Make analysis and determination. Analyze and read the results.
3.6 Allowable difference
The difference between the analysis results between laboratories shall not be greater than the allowable difference as listed in Table 2.
4.3.1.7 Desulfurization tube, which is filled with active manganese dioxide (4.2.5).
4.3.1.8 Porcelain boat, 88 mm or 97 mm in length, which shall be pre-fired in a tube combustion furnace at 1200 °C with oxygen until carbon-free; or it can be burned in a high-temperature furnace at 1000 °C for more than 4 hours. After cooling, it is stored in a desiccator containing soda asbestos (or soda lime) and anhydrous calcium chloride without grease.
4.3.1.9 Eudiometer, containing sodium chloride solution (4.2.10) or sulfuric acid solution (4.2.7). The scale of each division is 0.05 mL, which is marked under the standard conditions of 16 °C and 101.32 kPa (760 mmHg).
4.3.1.10 Absorber, containing potassium hydroxide solution (4.2.9).
4.3.1.11 Small piston, one side can be vented to the atmosphere.
4.3.2 Long hook, which is made of low-carbon nickel-chromium wire or heat- resistant alloy wire.
4.3.3 Mercury barometer, the barometric pressure value of which shall be corrected according to formula (1).
Where:
p - Corrected air pressure value, kPa;
p’ - The barometric pressure measured by a mercury barometer, kPa;
t - The temperature where the mercury barometer is located, °C;
Φ - Latitude where the mercury barometer is located, (°);
H - The altitude where the mercury barometer is located, m.
4.4 Sampling and sample preparation
Take and prepare sample according to GB/T 4010. The ferromanganese-silicon and blast furnace ferromanganese samples shall pass through a 0.125 mm
sieve; the medium-and-low-carbon ferromanganese samples shall pass
through a 0.149 mm sieve.
4.5 Analytical procedures
4.5.1 Sample mass
Weigh the sample and flux according to Table 3. The mass of sample is
Do a blank test with the sample.
5.5.3 Preparation for analysis
Connect the gravimetric carbon fixation device. Raise the furnace temperature to 1200 °C ~ 1350 °C. Check the air tightness of the instrument and the oxygen purification effect. Introduce oxygen at a rate of 300 mL/min ~ 500 mL/min. Remove the absorption bottle after 15 min ~ 20 min (12). Weigh it at room temperature. Put it back.
5.5.4 Determination
Place the sample (5.5.1) in the porcelain boat (8). Cover the flux according to Table 4. Push the porcelain boat into the highest temperature location of the high-temperature combustion tube. Immediately plug the oxygen inlet end. After about 1 min, lead in oxygen at a rate of 300 mL/min ~ 500 mL/min. After about 1 min, when the combustion is over, continue to lead in oxygen for 15 min ~ 20 min, so that carbon dioxide can be completely eliminated from the high
temperature combustion tube, desulfurization bottle and drying tower.
Cut off the oxygen flow, close the weighed absorption bottle (12) and take out the porcelain boat. Check the frit. After confirming that the combustion is complete, remove the closed absorption bottle and weigh it at room
temperature. The increased mass of the absorption bottle is the carbon dioxide absorbed.
5.5.5 Result calculation
Calculate the carbon content (mass fraction) in the sample according to formula (3):
Where:
m2 - The mass of carbon dioxide in the specimen, in grams (g);
m1 - The mass of carbon dioxide in the blank of the specimen, in grams (g); m - The mass of sample, in grams (g);
0.2729 - Conversion factor for converting carbon dioxide into carbon.
5.6 Allowable difference
The difference between the analysis results between laboratories shall not be greater than the allowable difference listed in Table 6.
6.3.2 High-frequency induction heating furnace, the output power of which is not less than 2 kW.
6.3.3 Power supply regulator, 3 kW.
6.3.4 Oxygen cylinder, which is equipped with a pressure reducing valve with a flow meter.
6.3.5 Crucible, diameter x height: 25 mm x 25 mm, which is burned for 4 h in a high-temperature heating furnace higher than 1200 °C or burned with oxygen to the lowest blank value.
6.4 Sampling and sample preparation
Take and prepare sample preparation according to GB/T 4010. All samples shall pass through the 0.177 mm sieve.
6.5 Analytical procedures
6.5.1 Sample mass
Weigh 0.500 g of sample, accurate to 0.0001 g.
6.5.2 Blank test
Do the blank test several times with the sample. Take the average value as the blank value. The blank value shall not be greater than 0.005% based on the calculation of 0.50 g specimen.
6.5.3 Preparation for analysis
6.5.3.1 Add 90 mL ~ 100 mL of cathode cup solution (6.2.9) to the cathode cup. 6.5.3.2 Add powdered barium carbonate (6.2.1) to the cathode cup to half full, then pour the anode cup solution (6.2.10) and stir with a glass rod. After standing still, the height of precipitated substance shall exceed the semi- permeable membrane; the platinum electrode shall be completely immersed in the solution above the sediment.
6.5.3.3 Add the reference electrode solution (6.2.11) to the reference electrode cup; it shall exceed the height of the semi-permeable membrane.
6.5.3.4 Check the gas path. After confirming that there is no air leakage, perform multiple “end point positioning” according to the specified operation of the instrument. Select the pH value of the absorption liquid to be about 9.5. 6.5.3.5 The standard sample used to analyze the sample with similar carbon content shall be measured according to the analysis step 6.5.4, to determine the “power compensation” position.
6.5.4 Determination
Place the sample (6.5.1) in a crucible (6.3.5) and cover it with 1.5 g of tungsten pellets (6.2.5), 0.3 g of pure iron (6.2.7) and 0.3 g ~ 0.5 g of tin particles (6.2.6). After the instrument is normal, control the flow rate of oxygen to 200 mL/min ~ 300 mL/min. Press the "electrolysis" and "reset" button. Close the piston leading to the absorption cup. Lower the furnace tube’s sealing plug. Place the crucible at the support seat in the high-frequency induction furnace. Push on the furnace tube bolt to seal. Open the piston leading to the absorption cup. Replace the air in the furnace. When the blank value stabilizes to the lowest value, press the high-pressure switch of the high-frequency induction furnace (start
timekeeping). The sample begins to burn. The carbon dioxide is gradually absorbed by the absorbing liquid and electrolyzed. Then release the "reset" switch. When the plate electrode current of the high-frequency induction furnace rises to the peak and continues for 1 min, cut off the high-voltage switch. From the beginning of the timekeeping until the carbon dioxide is absorbed by all the absorption liquid for about 4 min ~ 6 min, read the pulse calculation; press the "auto-reset" switch. Close the piston leading to the absorption cup. Lower the furnace tube to seal. Take out the crucible.
6.5.5 Result calculation
Calculate the carbon content (mass fraction) in the specimen according to formula (4):
Where:
A - Pulse count of the specimen;
A0 - Pulse count of sample blank;
M - Amount of sample, in grams (g);
0.5 × 10-6 - Each pulse count is equivalent to the mass of carbon, in grams (g).
6.6 Allowable difference
The difference between the analysis results between laboratories shall not be greater than the allowable difference listed in Table 7.