GB/T 5687.3-1985 Chemical analysis methods for ferrochrome - Molybdenum blue photometric method for determination of phosphorus content

This standard is applicable to the determination of phosphorus content in ferrochrome and ferrochrome nitride. Determination range: <0.15%. This standard complies with CB 1467-78 "General Principles and General Provisions for Chemical Analysis Methods of Metallurgical Products". This standard is equivalent to the Japanese Industrial Standard JIS G 1313/1978 "Analysis Method for Ferrochrome". GB/T 5687.3-1985 Chemical Analysis Method for Ferrochrome Determination of Phosphorus Content by Molybdenum Blue Photometry GB/T5687.3-1985 Standard Download Decompression Password: www.bzxz.net

National Standard of the People's Republic of China
Methods for chemical analysis of ferrochromium The molybdenum blue photometric method for the determination of phosphorus content This standard is applicable to the determination of phosphorus content in ferrochromium and ferrochromium nitride. Determination range: 0.15%. This standard complies with GB1467-78 "General Principles and General Provisions for Chemical Analysis Methods of Metallurgical Products". This standard is equivalent to the Japanese industry standard JIS G1313/1978 "Analysis Methods for Ferrochromium". 1 Method Summary
UDC 669.15' 26
：546.18
GB 5687.3-85
The sample is decomposed with perchloric acid or melted with alkali to oxidize phosphorus to orthophosphoric acid, chromium is removed with perchloric acid and sodium chloride, iron is reduced with sodium bisulfite, ammonium molybdate and hydrazine sulfate are added to react to form phosphomolybdenum blue, and its absorbance is measured on a spectrophotometer. 2 Reagents
2.1 Sodium peroxide.
Sodium chloride is used after drying.
Hydrochloric acid (01.19g/m1).
Bromolybdenum saturated hydrochloric acid.
Hydrochloric acid (1+1)
Perchloric acid (p1.67g/ml).
Sulfuric acid (1+1).
Ammonium hydroxide (p0.90g/ml)
Ammonium hydroxide (1+50).
Ferric chloride solution (1%).
Sodium bisulfite solution (10%).
Color developer solution.
Weigh 20g of ammonium molybdate [(NH,)MoO2·4H2O] and dissolve it in 100ml of warm water, then add 700ml of sulfuric acid 2.12.1
(2.7), cool and dilute with water to 1L, mix. 2.12.2 Weigh 1.5g of hydrazine sulfate, dissolve it in water, dilute to 1L, mix. 2.12.3 When using, take 25ml of ammonium molybdate solution (2.12.1), 10ml of hydrazine sulfate solution (2.12.2) and 65ml of water and mix well. Use 25ml each time.
2.13 Phosphorus standard solution: Weigh 0.4394g potassium hydrogen phosphate (KH, PO.) which has been dried to constant weight at 105℃ and stored in a desiccator, dissolve it with appropriate amount of water, transfer it into a 1000ml volumetric flask, dilute it to the mark with water, and mix it well. This solution contains 0.1mg phosphorus in 1ml. 3 Instruments
Spectrophotometer.
National Bureau of Standards Issued on December 4, 1985
Implementation on October 1, 1986
GB5687.3-85
4.1 High carbon ferrochrome samples should pass through a 0.125nm sieve hole. 4.2 Nitride ferrochrome samples should pass through a 0.088mm sieve hole. 4.3 Micro-carbon, low-carbon, and carbon ferrochrome samples (drilled samples) should pass through a 1.68mm sieve hole. 5 Analysis steps
5.1 Sample pressureWww.bzxZ.net
Weigh the sample according to Table 1.
Phosphorus,
5.2 Empty test
Carry out the empty test together with the sample.
5.3 Determination
5.3.1 Sample acid dissolution method
Sample amount, g
5.3.1.1 Place the sample (5.1) in a 300ml beaker, cover with Table 1Ⅲ, add 20ml bromine saturated hydrochloric acid (2.4), heat until the sample is completely dissolved, then add 20ml chloric acid (2.6), wait until it evaporates and emits white light, continue heating, and keep heating for about 10 minutes while the vapor of perchloric acid refluxes along the wall of the beaker.
5.3.1.2 While heating the solution, add 1.5ml hydrochloric acid (2.3) to volatilize the chromium, continue heating to oxidize the reduced chromium, Add 5 ml of hydrochloric acid (2.3) and remove chromium repeatedly. Then add about 1 g of sodium chloride (2.2) while heating to volatilize the chromium. Repeat the operation of adding sodium chloride (2.2) until no brown vapor of chromium chloride appears and smoke continues to be emitted to remove chlorine. 5.3.1.3 After natural cooling, add 40 ml of water to dissolve the soluble salts, filter into a 250 ml container bottle with a filter paper containing a small amount of filter paper pulp, wash with warm water 4 to 5 times, cool to room temperature with running water, dilute with water to the scale, and mix well. 5.3.1.4 Transfer 25.00 ml of solution (5.3.1.3) to a 100 ml volumetric flask, add 10 ml of sodium bisulfite solution (2.11) and heat in a boiling water bath until the solution is colorless. Immediately add 25 ml of color development solution. 5.3.1.5 Transfer part of the solution to a colorimetric III of appropriate thickness, and use the empty test solution accompanying the sample as a reference to measure the absorbance at a wavelength of 825 nm on a spectrophotometer. Draw the corresponding phosphorus amount on the curve from 1. 5.3.2 Alkali fusion method of sample
5.3.2.1 Place the sample (5.1) in a 130m nickel crucible, add 10g of sodium peroxide (2.1), stir well, and cover with 1g of sodium peroxide (2.1). Slowly heat the sample to melt it, and then keep it at about 700 for about 5 minutes, and shake it continuously to melt it. 5.3.2.2 After natural cooling, place the crucible at 1500m 1. Add 100ml hot water to a beaker to make the molten material come out, take it out and wash it with water. After the solution cools down, neutralize it with sulfuric acid (2.7) and add 10ml excess, then add 3ml ferric chloride solution (2.10), neutralize it with ammonium hydroxide (2.8) and add 5ml excess, slowly boil for 1min, filter the precipitate with a filter paper, and wash it with ammonium hydroxide (2.9). 5.3.2.3 Rinse the precipitate with water and hydrochloric acid (2.5) into a 300ml beaker, heat and dissolve it, add 10ml perchloric acid (2.6) to evaporate all the fumes, oxidize the remaining chromium, then add about 1g sodium chloride (2.2) while heating to make the chromium evaporate, repeat the operation of adding sodium chloride until no brown chromium chloride vapor appears, and continue to remove chlorine. 5.3.2.4 After cooling down, add 40ml perchloric acid (2.6) to evaporate all the fumes, oxidize the remaining chromium, then add about 1g sodium chloride (2.2) while heating to make the chromium evaporate, repeat the operation of adding sodium chloride until no brown chromium chloride vapor appears, and continue to remove chlorine. Dissolve soluble salts in water, filter on a 250ml volumetric plate with filter paper with a small amount of filter paper pulp, wash with warm water 4-5 times, cool to room temperature, dilute with water to scale, and mix. Take 25.00ml of solution (5.3:2.4) in 5.3.2.5, transfer to a 100ml volumetric flask, and proceed as per 5.3.1.4 starting with the addition of 10ml328
GB 5687.3-85
sodium chloride sulfite solution (2.11) and 5.3.1.5. 6 Drawing of working curve
Transfer 0, 1.00, 2.00, 3.00, 4.00, 5.00 ml of phosphorus standard solution (2.13) to a 100 m2 beaker respectively, add 5 ml of perfluoric acid (2.6), heat and then evaporate to perchloric acid vapor, and proceed as in 5.3.1.3 to 5.3.1.5, but use the reagent blank as reference. Draw a curve with phosphorus as the horizontal axis and the measured absorbance as the vertical axis. Calculation of analysis results
Calculate the phosphorus content according to the following formula:
m. × r × 1000
Where: m—the amount of phosphorus obtained from the curve, mg, mp—the maximum amount of sample, and
—the ratio of the test solution.
8 Allowable difference
The difference between the analysis results of laboratories should not be greater than the allowable difference listed in Table 2. Table 2
1),020 -0.040
0.040 - 0.060
0.060-0.100
× 100
GB 5687.3-85
Appendix A
Determination of phosphorus content by photometric method without removing chromium and molybdenum blue
(reference)
A.1 Acid dissolution method: Decompose the sample according to 5.3.1.1, filter according to 5.3.1.3, take 25.00ml of solution from the 250ml volumetric flask, transfer them into 100ml volumetric flasks respectively, develop color according to 5.3.1.4 for one part; add 10ml sodium bisulfite solution (2.11) to the other part, heat in a boiling water bath to reduce the chromium, and add 25ml of color developer solution without ammonium molybdate. Heat the two solutions in a boiling water bath for 20-25 minutes, dilute to scale after cooling, mix well, and measure absorbance according to 5.3.1.5 below, using the other solution without ammonium molybdate as a reference.
A.2 Alkali fusion method: After decomposing and precipitating the sample according to 5.3.2.1 and 5.3.2.2, operate according to 5.3.2.3 until perchloric acid fumes are emitted. No chromium removal is required, that is, proceed according to 5.3.2.4, and finally according to A.1. Take two portions of 25.00 ml of solution from a 250 ml volumetric flask and continue until the absorbance is measured.
Additional Notes:
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 original Ministry of Metallurgical Industry Standard YB584-65 "Chemical Analysis Method of Ferrochrome" will be invalid. 33
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