This standard is applicable to the determination of silicon content in ferrochrome and ferrochrome nitride. Determination range: 1.00-6.00%. This standard complies with GB 1467-78 "Metallurgical product chemistry: General principles and general provisions for analytical method standards". This standard is equivalent to the Japanese Industrial Standard JIS G 1313/1978 "Methods for chemical analysis of ferrochrome". GB/T 5687.2-1985 Methods for chemical analysis of ferrochrome Gravimetric determination of silicon content GB/T5687.2-1985 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Methods for chemical analysis of ferrochromiumThe gravimetric method for the determinationof silicon content
This standard is applicable to the determination of silicon content in ferrochromium and ferrochromium nitride. Determination range: 1.00～6.00%. UDC 669.15' 26
：543.21
：546.28
GB 5687. 2—85
This standard complies with GB1467-78 "General Principles and General Provisions of Standards for Chemical Analysis Methods of Metallurgical Products". This standard is equivalent to the Japanese industry standard JIS G1313/1978 "Methods for Chemical Analysis of Ferrochromium". 1 Method Summary
The sample is dissolved in hydrochloric acid (or melted with alkali and then dissolved in hydrochloric acid), treated with fuming perchloric acid to make silicon insoluble, filtered, burned and weighed; treated with hydrofluoric acid to evaporate silicon dioxide, burned and weighed, and the silicon content is calculated from the difference between the two weighings. 2 Reagents
Melting agent (mix 2 parts of sodium peroxide with 1 part of anhydrous sodium carbonate). 2.2 Hydrochloric acid (1+2).
2.3 Hydrochloric acid (1+5).
Hydrochloric acid (1+10).
Perchloric acid (01.67g/ml).
Hydrofluoric acid (1.15g/ml).
Sulfuric acid (1+3).
Hydrogen peroxide (p1.10g/ml)
Saturated ammonium thiocyanate solution.
3 Sample
High carbon ferrochrome samples should pass through 0.125mm sieve. 3.1bzxZ.net
Nitrided ferrochrome samples should pass through 0.088mm sieve. 3.2
3.3Micro carbon, low carbon, and t carbon ferrochrome samples (drilled samples) should pass through 1.68mm sieve. 4 Analysis steps
4.1 Sample quantity
Weigh 1.000g sample.
4.2 Empty self-test
Perform an empty test with the sample.
4.3 Determination
4.3.1 Acid dissolution method of sample
4.3.1.1 Place the sample (4.1) in a 300ml beaker 1, cover with a watch glass, add 60ml hydrochloric acid (2.3) and heat to decompose, then add 20ml perchloric acid (2.5), heat to evaporate until smoke appears, continue heating, and continue heating for 15 to 20 minutes while the perchloric acid vapor refluxes along the wall of the beaker.
4.3.1.2 After natural cooling, add about 150ml warm water to dissolve soluble salts, add 10ml hydrogen peroxide (2.8) in small portions to reduce chromium, boil for about 1min, filter immediately with medium-speed quantitative filter paper, scrub the residue adhering to the wall of the beaker with a rubbing stick and move it to the filter paper, first wash with warm hydrochloric acid (2.4) until there is no reaction of iron ions (check the last washing liquid with saturated ammonium thiocyanate solution until it does not appear orange-red), then wash with warm water until there is no acidity. 4.3.1.3 Move the precipitate together with the filter paper into platinum, bake, first low-temperature ash, then burn at about 1100℃ to constant weight, cool and weigh its mass.
4.3.1.4 Add a few drops of sulfuric acid (2.7) to a platinum crucible to wet the residue, add 5 ml of hydrofluoric acid (2.6), slowly heat until the sulfuric acid smoke is gone, burn in a high-temperature furnace at about 1100℃ to constant weight, and weigh it after cooling. 4.3.2 Alkali melting method of sample
4.3.2.1 Place the sample (4.1) in a 30ml nickel crucible, add 10g of melting agent (2.1), stir evenly, and then cover with 1g of melting agent (2.1). Slowly heat the sample to melt it, keep it at about 700℃ for about 5 minutes, and shake it continuously to melt it. 4.3.2.2 After natural cooling, place the crucible in a 500ml beaker containing 60ml hydrochloric acid (2.2) to leach the molten material. Wash it with water and take it out. Then add 60ml perchloric acid (2.5) and heat it on a sand bath to evaporate until it is smooth. Continue heating so that the vapor of perchloric acid refluxes along the wall of the beaker. Continue heating for 15 to 20 minutes. The following shall be carried out according to 4.3.1.2 to 4.3.1.4. Note: If the silicon content of the sample is high, both the filtrate and the washing liquid must be recovered, that is, the filtrate and washing liquid shall be placed in a 500ml beaker, 10ml perchloric acid (2.5) shall be added, and it shall be heated on a sand bath until it is smooth and volatile. The filtrate and washing liquid shall be refluxed for 15 minutes. The following shall be carried out according to 4.3.1.2. The first silicon oxide precipitation shall be combined, and then 4.3.1.3 and 4.3.1.4 shall be carried out.
5 Calculation of analysis results
Calculate the percentage of silicon according to the following formula:
Formula: m-
［(m1-m2)-(mg-m4）］ × 0.4674mo
-The mass of impure silicon dioxide and platinum crucible, g: The mass of the residue and platinum crucible after hydrofluoric acid treatment, g: The mass of impure silicon dioxide and platinum crucible measured in the empty test, g; m--The mass of the residue and platinum crucible measured in the narrow test after hydrofluoric acid treatment, g; -Sample, g;
6 Allowable difference
"Conversion factor of silicon oxide to silicon. The difference in analysis results between laboratories should not be greater than the allowable difference listed in the following table. Silicon
1.00~2.50
2.50 ~ 6.00
Allowable difference
× 100
Additional Notes:
GB5687.2—85
This standard is proposed by the Ministry of Metallurgical Industry of the People's Republic of China. This standard is drafted by Shanghai Ferroalloy Factory. From the date of implementation of this standard, the former Ministry of Metallurgical Industry Standard YB584—65 "Methods for Chemical Analysis of Ferrochrome" shall be invalidated. 326
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