GB/T 5687.8-1988 Chemical analysis methods for ferrochrome - Determination of sulfur content by infrared absorption method

GB/T 5687.8-1988 Chemical analysis method for ferrochrome - Determination of sulfur content by infrared absorption method GB/T5687.8-1988 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Methods for chemical analysis of ferrochromium
Determination of sulfur content by infrared absorption method
Methods for chemical analysis of ferrochromiumThe infrared absorption method for thedetermination of sulfur contentThis standard is applicable to the determination of sulfur content in ferrochromium. Determination range: 0.005%~～0.070%. UDC 669.15'26
GB 5687.8—88
This standard complies with GB1467-78 "General Principles and General Provisions of Standards for Chemical Analysis Methods of Metallurgical Products". 1 Method Summary
The sample is heated and burned in the oxygen flow of a high-frequency induction furnace. The generated sulfur dioxide is carried by the oxygen to the measuring chamber of the infrared analyzer. The sulfur dioxide absorbs infrared energy of a specific wavelength. The absorbed energy is proportional to the sulfur dioxide concentration. The sulfur content can be measured according to the change in the energy received by the detector.
2 Reagents and Materials
2.1 Magnesium Perchlorate: Anhydrous, Granular.
2.2 Caustic Soda Asbestos: Granular.
2.3 Glass Wool.
2.4 Tungsten Granules: Sulfur content less than 0.0002%, particle size 0.8~1.4mm. 2.5
Tin Granules: Sulfur content less than 0.0003%, particle size 0.4~0.8mm. Pure Iron: Purity greater than 99.8%, sulfur content less than 0.002%, particle size 0.8~~1.68mm. 2.6
Oxygen: Purity greater than 99.95%, other grades of oxygen can also be used if a low and consistent blank can be obtained. 2.8 Power Gas Source: Nitrogen or compressed air, with impurities (water and oil) less than 0.5%. 2.9 Quality crucible: Φ×hmm: 23×23 or 25×25, and burned in a high temperature heating furnace above 1200℃ for 4h or burned with oxygen until the blank value is the lowest.
2.10 Crucible clamp.
3 Instruments and equipment
3.1 Infrared absorption sulfur analyzer (sensitivity is 1.0ppm) The device is shown in the figure.
Approved by the Ministry of Metallurgical Industry of the People's Republic of China on February 2, 1988 and implemented on March 1, 1989
GB 5687.8-88
1 Oxygen cylinder; 2-two-stage pressure regulator, 3-gas washing bottle, 4, 9-drying tube; 5-pressure regulator; 6-high frequency induction furnace; 7-combustion tube: 8-dust collector: 10-flow controller: 11-sulfur dioxide infrared detector 3.1.1 Gas washing bottle (3): Contains caustic soda asbestos (2.2). 3.1.2 Drying tube (4, 9): Contains magnesium perchlorate (2.1). 3.2 Gas source
3.2.1 The carrier gas system includes an oxygen container, a two-stage pressure regulator and a timing control part that ensures the provision of appropriate pressure and rated flow. 3.2.2 The power gas source system includes power gas (nitrogen or compressed air), a two-stage pressure regulator and a timing control part that ensures the provision of appropriate pressure and rated flow.
3.3 The high-frequency induction furnace
Should meet the requirements of the melting temperature of the sample.
3.4 ​​Control system
3.4.1 The microprocessor system includes a central processing unit, a memory, a keyboard input device, an information center display screen, an analysis result display screen and an analysis result printer, etc.
3.4.2 The control functions include automatic loading and unloading of crucibles and furnace lifting and lowering, automatic cleaning, analysis condition selection and setting, monitoring and alarm interruption of the analysis process, analysis data collection, calculation, correction and processing, etc. 3.5 Measurement system
Mainly composed of an electronic balance (sensitivity not greater than 1.0 mg) controlled by a microprocessor, an infrared analyzer and electronic measuring elements. 4 Sample
The sample should all pass through a 1.68 mm sieve.
5 Analysis steps
5.1 Sample quantity
Weigh 0.500 g of sample.
5.2 Blank test
Weigh 0.500 g of a pure iron standard sample with a sulfur content less than 20 ppm and place it in a crucible (2.9) pre-filled with 0.300 ± 0.005 g of tin particles (2.5), cover it with 1.500 ± 0.005 g of tungsten particles (2.4) in the same range or channel, and measure according to 5.5, repeating a sufficient number of times until a low and relatively consistent reading is obtained (the blank value should be equal to the difference between the measured sulfur content and the known sulfur content of the standard sample). Record at least three readings, calculate the average blank value, and input the blank value into the analyzer according to the instrument manual. The instrument will then perform electronic compensation for the blank value when measuring the sample. 5.3 Analysis Preparation
5.3.1 Debug and check the instrument according to the instrument manual to ensure that the instrument is in a normal and stable state. 3H
5.3.2 Select and set the best analysis conditions.
GB5687.8—88
5.3.3 Use standard samples and flux to perform two tests according to 5.5 to determine whether the instrument is normal. 5.3.4 Weigh several portions of 0.500g of a standard sample (or pure iron standard sample) with a sulfur content of about 0.0025%, and measure according to 5.5. The result fluctuation should be within the range of ±0.0003%, otherwise the instrument sensitivity should be adjusted according to the instrument requirements. 5.4 Calibration test
5.4.1 According to the sulfur content of the sample to be tested, select the corresponding range or channel, and select three standard samples of the same type (the content of the sample to be tested should fall within the sulfur content range of the selected three standard samples), and calibrate in sequence. The fluctuation of the results should be within the allowable error range to confirm the linearity of the system, otherwise the linearity of the system should be adjusted according to the instrument manual. 5.4.2 Different ranges or channels should be measured and calibrated separately. 5.4.3 When the analysis conditions change, such as the instrument has not been preheated to 1h, the blank value of the oxygen source, crucible or flux has changed, it is required to re-measure the blank and calibrate.
5.5 Determination
5.5.1 According to the sulfur content range of the sample to be tested, select the best analysis conditions of the instrument: such as the combustion integration time of the instrument, the setting of the comparison level (or set number), etc.
5.5.2 Place the sample (5.1) in a crucible (2.9) pre-filled with 0.30g of tin particles (2.5), cover with 1.50g of tungsten particles (2.4), take the crucible with tongs and place it on the crucible stand on the furnace, operate according to the instrument manual, start analysis and read the results. 6 Allowable Difference
The difference in analysis results between laboratories should not be greater than the allowable difference listed in the following table. %
0. 005~0. 015
≥0. 015～0. 025
>0. 025 ~0. 045
>0. 045-~0. 070Www.bzxZ.net
Additional Notes:
This standard was drafted by Jilin Ferroalloy Plant and Xinyu Iron and Steel Plant. The main drafters of this standard are Chang Yanfu, You Youshen and Liu Jinhua. Allowance
From the date of implementation of this standard, the former Ministry of Metallurgical Industry Standard YB584-65 "Chemical Analysis Method of Ferrochromium" shall be invalid. 3.13
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