GB/T 4333.5-1997 Chemical analysis methods for ferrosilicon - EDTA volumetric method for determination of aluminum content
Some standard content:
GB/T4333.5—1997
This standard is revised based on GB4333.5--84. In terms of technical content, it is not equivalent to the 7.2 EDTA volumetric method in JISG1312-1989 for determining aluminum content.
This standard mainly revises the allowable difference. From the date of entry into force, this standard will replace GB4333.5-84. This standard is proposed by the Ministry of Metallurgical Industry of the People's Republic of China. This standard is under the jurisdiction of the Information Standards Research Institute of the Ministry of Metallurgical Industry. The drafting units of this standard are: Emei Ferroalloy (Group) Co., Ltd., Maanshan Iron and Steel Company. The main drafters of this standard are: Hou Wenzhi, Yao Shuoquan, Bao Lifen. This standard was first issued on April 9, 1984. 169
1 Scope
National Standard of the People's Republic of China
Methods for chemical analysis of ferrosiliconthe EDTA volumetric method for the determinationof aluminium content
This standard specifies the determination of aluminium content in ferrosilicon by the EDTA volumetric method. This standard is applicable to the determination of aluminium content in ferrosilicon. Determination range: 0.60%~5.00%. 2 Summary of method
GB/T 4333.5—1997
Replaces GB4333.5—84
The sample is decomposed with nitric acid and hydrofluoric acid, and fluorine is removed by fuming with perchloric acid. After filtering out the residue, the filtrate is extracted and removed with methyl isobutyl ketone in a 7 mol/L hydrochloric acid medium. The residue is melted with sodium bisulfate, leached and added to the main solution, separated from calcium and manganese by ammonium benzoate precipitation, and then separated from titanium by copper iron reagent. Then, excess EDTA is added. Under the condition of pH 5.5, PAN is used as an indicator, and the excess EDTA is titrated with copper sulfate standard solution. Sodium fluoride is added to release the EDTA complexed with aluminum, and then back-titrated with copper sulfate standard solution. The percentage of aluminum is calculated based on the consumption of standard solution.
3 Reagents
Sodium bisulfate (superior grade).
3.2 Sodium chloride (superior grade).
3.3 Nitric acid (pl.42g/mL).
3.4 Hydrochloric acid (pl.19g/mL).
3.5 Hydrochloric acid (1+1).
3.6 Hydrochloric acid (1+4).
3.7 Hydrochloric acid (7+5).
3.8 Hydrochloric acid (1+99).
3.9 Hydrochloric acid (5+95).
) Hydrofluoric acid (pl.15g/mL).
Perchloric acid (pl.67g/ml.).
Sulfuric acid (pl.84 g/mL).
Ammonia water (p0.90g/mL), ultrapure.
Ammonia water (1+1).
Ammonia water (1+4).
Methyl isobutyl ketone.
Copper iron reagent solution (0.6g/L), prepared when used. Approved by the State Administration of Technical Supervision on November 11, 1997, 170
Implemented on May 1, 1998
3.18 Ammonium benzoate solution (100g/L). GB/T 4333. 5 -- 1997
3.19 Ammonium benzoate washing solution: Take 10 mL of ammonium benzoate solution (3.18), 2 mL of glacial acetic acid (pl.05 g/mL), dilute to 100 mL with water, and mix well.
3.20 Ammonium acetate solution (200 g/I.).
3.21 Hydroxylamine hydrochloride solution (100 g/L). 3.22 Saturated sodium fluoride solution.
3.23 Acetic acid-sodium acetate buffer solution (pH 5.5): Weigh 200 g of sodium acetate (CH,COONa·3H2O), dissolve in 500 mL of water, add 9 mL of glacial acetic acid (p1.05 g/mL). Dilute to 1000 mL with water, and mix well. 3.24 p-Nitrophenol solution (0.02 g/L). 3.25PAN[1-(2-pyridylazo)-2-naphthol I ethanol solution (1.0 g/L). 3.26Aluminum standard solution: weigh 0.2000g pure aluminum (99.99%), place in a 250mL beaker, add 30mL hydrochloric acid (3.5), heat to dissolve, if there is still insoluble matter, add nitric acid dropwise to help dissolve, boil and dissolve, cool, transfer to a 1000mL volumetric flask, dilute to scale with water, and mix. This solution contains 0.0002g aluminum in 1mL.
3.27Copper sulfate standard solution, c(CuSO4·5H,O)=0.0027mol/L. 3.27.1 Preparation: Weigh 1.7967g of copper sulfate (CuSO, ·5H.0) and place it in a 300mL beaker. After dissolving in water, transfer it to a 1000mL volumetric flask, add 2-3 drops of sulfuric acid (3.12), dilute to scale with water, and mix. 3.27.2 Calibration: Transfer 20.00mL of LEDTA standard solution (3.28) and place it in a 300mL beaker. Add 60mL of water and 2 drops of p-nitrophenol solution (3.24). Adjust with hydrochloric acid (3.6) and ammonia water (3.14 and 3.15) until the yellow color just fades. Add 20mL of acetic acid-sodium acetate buffer solution (3.23), heat and boil, remove, add 7-8 drops of PAN ethanol solution (3.25), and titrate with copper sulfate standard solution (3.27) until purple-red. Calculate the conversion factor f of copper sulfate standard solution equivalent to EDTA standard solution according to formula (1): f = V./V2
Wherein: Vi is the volume of EDTA standard solution transferred, mL; V is the volume of copper sulfate standard solution consumed during titration, mL. V,
3.28 Disodium ethylenediaminetetraacetic acid (EDTA) standard solution c(EDTA) = 0.01 mol/L. (1)
3.28.1 Preparation: Weigh 3.7226 g EDTA into a 300 mL beaker, add water to dissolve, transfer to a 1000 ml volumetric flask, dilute to scale with water, and mix well. www.bzxz.net
3.28.2 Calibration: Pipette 20.00mL aluminum standard solution (3.26) into a 300mL beaker, add 30mL water and 25.00mL EDTA standard solution (3.28), boil for 1min, and then add 2 drops of p-nitrophenol solution (3.24) as in 5.3.6. Perform a blank test of the reagent at the same time. Calculate the titer of the EDTA standard solution for aluminum according to formula (2): T == 0.000 2 XV/f(V3 - V.) Where: T-the titer of the EDTA standard solution for aluminum, g/mL; V-the volume of the aluminum standard solution pipetted, mL; V-the volume of the copper sulfate standard solution consumed when sodium fluoride is added to the test solution and then back-titrated, ml; V.-the volume of the copper sulfate standard solution consumed when sodium fluoride is added to the test solution and then back-titrated in the reagent blank test, mL; f-the conversion factor of the copper sulfate standard solution equivalent to the EDTA standard solution. 4 Sample
The sample should pass through a 0.125 mm sieve.
5 Analysis steps
5.1 Sample quantity
.....( 2 )
For aluminum content of 0.60% to 1.10%, weigh 0.5000 g of sample; for aluminum content of 1.10% to 2.50%, weigh 0.2500 g of sample; for aluminum content greater than 2.50%, weigh 0.1500 g of sample.
5.2 Blank test
Perform a blank test together with the sample.
5.3 Determination
GB/T4333.5—1997
5.3.1 Place the sample (5.1) in a platinum dish, moisten it with a small amount of water, add 10ml nitric acid (3.3), add 8mL hydrofluoric acid (3.10) dropwise, and heat until the sample is completely dissolved after the action stops. Add 8mL perchloric acid (3.11), heat until smoke is dry, cool slightly, rinse the blood wall with water, add 4mL perchloric acid (3.11), continue to heat until smoke is dry. Cool slightly, add 8mL hydrochloric acid (3.4), heat to dissolve salts, add 30ml. hot water, filter with slow quantitative filter paper into a 150mL conical flask, wash the residue and filter paper with hot hydrochloric acid (3.9) 7~~8 times, and then wash with water 2~3 times, and retain the residue and filter paper.
5.3.2 Heat the filtrate and evaporate it to near dryness, add 15mL hydrochloric acid (3.7), heat to dissolve the salts, cool, rinse into a 60ml separatory funnel with 5ml hydrochloric acid (3.7), add 20mL methyl isobutyl ketone (3.16), shake for 1min, let stand to separate, put the aqueous phase into the original conical flask, add 10ml hydrochloric acid (3.7) into the separatory funnel, shake for 30s, let stand to separate, put the aqueous phase back into the original conical flask. Discard the organic phase. Boil the solution in the conical flask.Remove the residual methyl isobutyl copper from the solution, add 10 mL nitric acid (3.3) and 5 mL perchloric acid (3.11), heat until smoke appears, remove chromium with 0.2 g sodium chloride in batches, and evaporate until nearly dry. Add 3 ml sulfuric acid (3.12), heat until sulfuric acid smoke appears, cool, add 10 mL water, heat to dissolve the salts, cool and transfer to a 400 mL beaker. This solution is the main liquid. 5.3.3 Place the residue together with the filter paper (5.3.1) in a platinum crucible, carbonize, burn in a high-temperature furnace at 700°C for 10 minutes, take out and cool, add 2 g sodium bisulfate (3.1), place on an electric furnace and bake for 10 minutes, place in a high-temperature furnace to melt until clear, cool, and immerse the molten block into the main liquid. 5.3.4 Dilute the solution to 150ml, add 10ml hydroxylamine hydrochloride solution (3.21), boil for 1min, remove, add 10ml ammonium acetate solution (3.20), adjust pH to 3~3.5 with ammonia water (3.14) (check with precision pH test paper), add 25ml ammonium benzoate solution (3.18), keep warm at about 95℃ for 15min, filter with medium-speed quantitative filter paper while hot, wash with hot ammonium benzoate washing solution (3.19). Put the precipitate and filter paper back into the original beaker, add 20ml nitric acid (3.3) and 8ml perchloric acid (3.11), heat until smoke appears and evaporate to 2ml, remove and cool slightly. 5.3.5 Add 20 mL of hydrochloric acid (3.5), heat to dissolve the salts, cool, dilute to 100 mL with water, cool to below 15°C, add 10 mL of cupric iron solution (3.17) dropwise while stirring, let stand for 1 to 2 min, filter with slow quantitative filter paper, wash the beaker and precipitate with hydrochloric acid (3.8), add 10 mL of nitric acid (3.3) and 5 mL of perchloric acid (3.11) to the filtrate, heat until smoke appears and the solution is about 3 mL, cool slightly, add 20 mL of water and heat to dissolve the salts.
5.3.6 Add EDTA standard solution (3.28) with about 5 ml excess, dilute to 60 ml with water, boil for 1 min, add 2 drops of p-nitrophenol solution (3.24), adjust with ammonia (3.14 and 3.15) and hydrochloric acid (3.6) until the yellow color of the solution just fades, add 20 ml of acetic acid-sodium acetate buffer solution (3.23), boil for 31 min, add 7-8 drops of PAN ethanol solution (3.25). Immediately titrate with copper sulfate standard solution (3.27) to red purple. Add 15 ml of sodium fluoride saturated solution (3.22), boil for 2 min, add 3 drops of PAN ethanol solution (3.25), and titrate with copper sulfate standard solution (3.27) to red purple as the end point (when the aluminum content is high, the end point is dark blue). 6 Calculation of analysis results:
Calculate the percentage of aluminum according to formula 3):
Al(%) T.f(V Vs)/m × 100
The titer of EDTA standard solution for aluminum, g/mL; Where: T—
f-Conversion factor of copper sulfate standard solution equivalent to EDTA standard solution; V—The volume of copper sulfate standard solution consumed when sodium fluoride is added to the test solution and then back-titrated, mL: V: The volume of copper sulfate standard solution consumed when sodium fluoride is added to the blank test with the sample and then back-titrated, ml.; Sample size, g.
7 Allowable difference
The difference in analysis results between laboratories should not be greater than the allowable difference listed in Table 1. 172
（3）
Aluminum content
0.60~0.80
≥0.80~1.20
>1.20~1.70
>1.70 ~ 2.50
>2.50~5.00
GB/T 4333.5-1997
Table 1 Allowable difference
Allowable difference
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