GB/T 4701.7-1985 Chemical analysis methods for ferrotitanium - Molybdenum blue spectrophotometric method for determination of phosphorus content
Some standard content:
National Standard of the People's Republic of China
Methods for chemical analysis of ferrotitaniumThe molybdenum blue spectrophotometric methodfor the determination of phosphorus contentThis standard applies to the determination of phosphorus content in ferrotitanium. Determination range: 0.010～0:150%. This standard complies with GB1467-78 "General Principles and General Provisions of Standards for Chemical Analysis Methods of Metallurgical Products". 1 Method Summary
UDC 669.15'295
GB 4701.7--85
The sample is decomposed with nitric acid and hydrofluoric acid, and sodium hydroxide is used to separate iron, titanium, etc. from phosphorus. The filtrate is acidified with hydrochloric acid, and ammonium hydroxide is added in the presence of ferric chloride to precipitate phosphorus into iron phosphate. Dissolve the tool in nitric acid, add perchloric acid and smoke to remove the nitric acid. Reduce iron with sodium bisulfite, add ammonium potassium acid to make phosphorus and ammonium molybdate generate phosphomolybdic heteropoly acid, reduce to phosphomolybdic blue with hydrazine sulfate, and measure its absorbance at a wavelength of 825 mm on a spectrophotometer.
2 Reagents
2.1 Hydrofluoric acid (specific gravity 1.15).
2.2 Perchloric acid (specific gravity 1.67).
2.3 Nitric acid (specific gravity 1.42).
2.4 Nitric acid (1 +2).
Nitric acid (1+50).
2.6 Hydrochloric acid (1+1).
Sulfuric acid (1+1).
2.8 Ammonium hydroxide (1+1).
2.9 Sodium hydroxide solution (20%).
2.10 Ferric chloride solution (10%): Weigh 10g ferric chloride (FeCl, ·6H,O) and dissolve it in 10ml hydrochloric acid (1+1), dilute to 100ml with water, and mix well.
2.11 Sodium ammonium sulfite solution (10%).
2.12 Color developer solution
2.12.1 Weigh 20g ammonium potassium (NH4Mo,O24*4H,O), dissolve in 100ml warm water4, add 700ml sulfuric acid (2.7), cool and dilute to 1000ml with water, mix well. 2.12.2 Weigh 0.75g hydrazine sulfate, dissolve in a small amount of water4 and dilute to 500ml, mix well. 2.12.3 Take 25ml solution (2.12.1), 10ml solution (2.12.2) and 65ml water, mix with a spoon. Prepare when needed. 2.13 Phosphorus standard solution: weigh 0.4394g potassium dihydrogen phosphate (KHPO,) which has been pre-dried at 110C for 1 to a constant amount, Dissolve in 100ml water, transfer to a 1000ml volumetric flask, dilute to the mark with water and mix. This solution contains 0.1mg phosphorus in 1ml. 3 Instrument
Spectrophotometer.
National Bureau of Standards Issued on April 15, 1985
Implementation on January 1, 1986
4 Sample
The sample should pass through a 0.125mm sieve. bZxz.net
5 Analysis steps
5.1 Sample quantity
Weigh the sample according to Table 1.
Phosphorus content, %
5.2 Blank test
Carry out a blank test along with the sample.
5.3 Determination
GB 4701.7—85
Sample volume, g
5.3.1 Place the sample (5.1) in a 100ml platinum dish or a 100ml polytetrafluoroethylene beaker, cover with Table III, add 20ml nitric acid (2.3) and add a small amount of hydrofluoric acid (2.1) dropwise until the sample is dissolved, remove the dish, add 10ml sulfuric acid (2.7), heat and evaporate until the sulfuric acid white smoke is almost gone, remove and cool, add 20ml hydrochloric acid (2.6), heat and dissolve Soluble salts, transfer to a 500ml beaker, dilute to about 200ml with warm water, slowly add sodium hydroxide solution (2.9) while stirring until a precipitate is formed and 40ml excess. Heat and boil for 3-5min, remove, cool to room temperature, transfer to a 500ml volumetric flask, dilute to scale with water, and mix well. 5.3.2 Dry filter the solution with precipitate (5.3.1) with medium-speed filter paper into a 250ml dry volumetric flask to the scale, and pour the solution into a 500ml l beaker, wash the volumetric flask with a small amount of water and put it into the beaker, neutralize with hydrochloric acid (2.6) until neutral and add 10ml excess, heat and boil for 1-2 minutes. Remove, add 5ml ferric chloride solution (2.10), neutralize with ammonium hydroxide (2.8) until a precipitate is formed and add 5ml excess, boil for about 1 minute, remove and let stand for a while to let the precipitate settle, filter with medium-speed filter paper, wash with warm water 2-3 times, dissolve the precipitate with hot nitric acid (2.4) on the funnel, and collect the solution in the original calcined In a cup, wash the filter paper thoroughly with hot nitric acid (2.5). Add 10 ml of perchloric acid (2.2), cover with blood, heat and evaporate until the perchloric acid vapor flows back along the inner wall of the beaker, continue heating for about 10 minutes, and when the volume of the solution is about 5-6 ml, remove and cool slightly, add about 30 ml of hot water, heat to dissolve the salts and boil for 1-2 minutes, filter with fast filter paper into a 100 ml volumetric flask, wash the filter paper with hot water, cool to room temperature, dilute with water to the mark, and mix. 5.3.3 Transfer 10.00 ml of solution (5.3.2) into a 100 ml volumetric flask, add 10 ml of sodium bisulfite solution (2.11), heat in a boiling water bath until the solution is colorless, add 25 ml of color developer solution (2.12.3), and heat in a boiling water bath for about 15 minutes, remove and cool to room temperature with running water, dilute with water to the mark, and mix. 5.3.4 Transfer part of the solution (5.3.3) to a cuvette, and use the blank sample as a reference. Measure its absorbance at a wavelength of 825 nm on a spectrophotometer, and find the corresponding phosphorus content from the working curve. 5.4I Plotting the curve
5.4.1 Weigh five portions of titanium iron (phosphorus content less than 0.002%) of the same gram as the sample, and place them in a set of 100ml platinum dishes or 100ml polytetrafluoroethylene beakers, and add 0.00, 2.00, 4.00, 6.00, and 8.00ml of phosphorus standard solution (2.13) respectively. The following is carried out according to 5.3.1 from the cover of Table III to 5.3.3. 5:4.2 Transfer part of the solution (5.4.1) into a cuvette, take the solution without phosphorus standard solution as reference, measure its absorbance at 825nm wavelength on a spectrophotometer, and draw a working curve with phosphorus content as abscissa and absorbance as ordinate. 185
6 Calculation of analysis results
Calculate the percentage of phosphorus content according to the following formula:
GB 4701.7-85
Where: mi——phosphorus content found on the curve of 1, g, ma——sample mouse, g;
test solution fraction ratio.
Analysis results are accurate to the third decimal place. 7 Allowable difference
The difference between analysis results of laboratories should not be greater than the allowable difference listed in Table 2. Table 2
0.010~0.040
:>0.040~0.080
>0.080-0.150
Additional Notes:
This standard is proposed by the Ministry of Metallurgical Industry of the People's Republic of China. This standard is drafted by Jinzhou Ferroalloy Factory of the Ministry of Metallurgical Industry. Allowance
From the date of implementation of this standard, the former Ministry of Metallurgical Industry Standard YB581-65 "Chemical Analysis Method of Ferrotitanium" shall be invalid. 186
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