This standard specifies the measurement method of iron content in copper and copper alloys. This standard is applicable to the determination of iron content in copper and copper alloys. Determination range: 0.001 5% to 0.50%. GB/T 5121.9-1996 Chemical analysis method for copper and copper alloys Determination of lead content GB/T5121.9-1996 Standard download decompression password: www.bzxz.net

1 Scope
National Standard of the People's Republic of China
Chemical analysis method for copper and copper alloys-Determination of iron contentCopper and copper alloys-Determination of iron contentGB/T 5121.9--- 1996
Replaces GB512).9
GB 5122. 3
635122.1285
GB 8002. 9
G3 652G.1
G3 8550. 1687
Part 1 Method 11,10-phenanthroline spectrophotometric determination of iron content This standard specifies the method for measuring the iron content in copper and copper alloys. This standard is applicable to the determination of iron content in copper and copper alloys. Determination range: 0.0015%~0.50%. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is revised, the versions shown are valid. All standards will be revised. Parties using this standard should explore the possibility of using the latest versions of the following standards. GB1.4-88 Guidelines for standardization work Provisions for the preparation of chemical analysis methods GB1467-78 General principles and general provisions for chemical analysis methods of metallurgical products GB772987 General principles for spectrophotometric methods for chemical analysis of metallurgical products 3 Method summary
The sample is dissolved in hydrochloric acid and hydrogen peroxide, and the trivalent iron chloride complex is extracted with 1-methyl-pentanone-2 in a hydrochloric acid medium of about 6 mol/L. It is reduced to divalent iron with ascorbic acid and back-extracted into the aqueous phase. The absorbance of the red complex of iron (II) and 1.10)-phenanthroline is measured at a wavelength of 510 nm on a spectrophotometer.
4 Reagents
4.1 1-Methyl-pentanone-2.
4.2 Gasoline (boiling point 40-100°C).
4.3 Sulfuric acid (pl.84 g/ml).
4.4 Hydrofluoric acid (p1.13 g/mL)
4.5 Hydrogen peroxide (30%).
4.6 Hydrochloric acid (7+3).
4.7 Hydrochloric acid (1+1).
4.8 Ascorbic acid solution (10 g/l.). Prepare when needed. 4.9 1,10-Phenanthroline buffer solution (2g/L): Weigh 1.0g 1,10-Phenanthroline (C2HNz·H,0) in a 600ml beaker and dissolve it with 5mL hydrochloric acid (4.7), add 215mL glacial acetic acid (pl.05g/mL) and stir, slowly add 265ml ammonia water (00.91g/ml) under constant stirring, and cool. The pH value of this solution should be 6.5±0.1. If necessary, it can be adjusted with glacial acetic acid (p1.05g/ml.) or ammonia water (p0.91g/ml.), then dilute with water to 500mL and mix. 4.10 Iron standard storage solution: Weigh 0.1000g pure iron and place it in a 150ml beaker. Add 20ml hydrochloric acid (p1.19g/ml). Heat until completely dissolved, cool. Transfer to a 1000ml volumetric flask, dilute to scale with water, and mix well. 1 ml of this solution contains (0.1 mg iron. 4.11 Iron standard solution: Pipette 50.00 ml of the iron standard stock solution into a 500 ml volumetric flask and dilute to the mark with water: Mix, 1 ml of this solution contains 10 μg iron.
5 Instruments
5.1 Spectrophotometer.
5.2 Acidometer.
Note: All glassware should be rinsed with hot hydrochloric acid (4.7) plus hydrogen peroxide until there is no iron on the surface. 6 Analysis steps
6.1 Samples
Weigh the sample according to Table 1, accurate to 0.0001 g. Table 1
Iron content, %
0. 001 5~0. 005 0
≥0. 005 0~0. 020
>0. 020~0. 10
>0. 10~0. 50
Sample amount,
Independently conduct two determinations and take the average value. 6.2 Blank test
Carry out a blank test with the sample.
6.3 Determination
6.3.1 Dissolve the sample
Total volume, ml
Sub-volume, mL
6.3.1.1 Place the sample (6.1) in a 150mL beaker, add 10ml hydrochloric acid (4.6), add 10ml peroxide in batches, and wait for the sample to dissolve. After the solution is completely dissolved, boil to remove excess hydrogen peroxide (if analyzing a sample containing chromium, slowly add 4 mL of sulfuric acid and heat to evaporate until white sulfur trioxide smoke appears in the tube for 3 to 5 minutes, remove and cool slightly, add 20 mL of hydrochloric acid (4.7) to warm and dissolve the salts), and cool. 6.3.1.2 When analyzing a sample with silicon as the main component, place the sample (6.1) in a polyethylene beaker, add 10 mL of hydrochloric acid (4.6), add 10 mL of hydrogen peroxide in portions, and 5 to 8 drops of hydrofluoric acid. After the sample is completely dissolved, transfer the solution into a 150 mL beaker with a small amount of hydrochloric acid (4.7) to wash the beaker wall, and the washing liquid is added to the beaker. Boil the main solution to remove excess hydrogen peroxide, and cool. 6.3.2 Solution treatment
6.3.2.1 According to Table 1, transfer the full volume of the test solution into a 125mL separatory funnel, and use 5~8mL of hydrochloric acid (4.7) to wash Table III and the beaker wall, and the washing liquid is merged into the main solution.
6.3.2.2 If it is necessary to separate, transfer the solution into a volumetric flask according to Table 1, wash the table dish and the beaker wall with hydrochloric acid (4.7), and the washing liquid is added to the volumetric flask , dilute to scale with hydrochloric acid (4.7), and mix. Pipette 10.00 mL of the test solution into a 125 mL separatory funnel and add 15 mL of hydrochloric acid (4.7). 6.3.3 Extraction
Add 20 mL of 4-methyl-pentanone-2 to the separatory funnel, shake for 15 seconds, let stand for stratification, discard the aqueous phase, and wash the organic phase with hydrochloric acid (4.7) 3 times, 20 mL each time, until there is no copper. If stratification is difficult, add 2 mL of gasoline to the emulsion mixture and shake it slightly to accelerate stratification. Repeat the extraction of iron from the organic phase with two 10 mL portions of ascorbic acid, shaking for 20 seconds each time. 6.3.4 Color development
Combine the aqueous phases of the two extractions into a 50 mL volumetric flask, add 5.0 mL of 1,10-phenanthroline buffer solution, dilute to 236
with water, and mix well.
6.3.5 Measurement
GB/T 5121.9—1996
Put part of the solution into a 2cm absorbent tube, and measure the absorbance at a wavelength of 510nm on a spectrophotometer with water as a reference. 6.3.6 Subtract the absorbance of the blank solution accompanying the sample, and find the corresponding iron from the working curve. 6.4 Drawing of the working curve
6.4.1 Take 0, 1.00, 2.00, 3.00, 4.00, 5.00mL of the iron standard solution, place them in a group of 50mL volumetric flasks, add 20ml of ascorbic acid, mix well, and let stand for 1min. Add 5.0mL of 1,10-phenanthroline buffer solution, dilute to the mark with water, and mix well. 6.4.2 Transfer part of the solution into a 2 cm absorption dish, use water as a reference, measure the absorbance at a wavelength of 510 nm on a spectrophotometer, subtract the absorbance of the blank solution from the measured absorbance, and plot a working curve with the iron content as the abscissa and the absorbance as the ordinate. Expression of analysis results
Calculate the percentage of iron according to formula (1):
ml.V. × 10-5
Where: mr-
The amount of iron found from the working curve, rg; the total volume of the test solution, mL;
V, the volume of the test solution taken, mL;
maThe mass of the test material·g.
× 100
The result is expressed to two decimal places. If the iron content is less than 0.10%, express it to 3 decimal places; if it is less than 0.010%, express it to 4 decimal places.
8 Allowable Difference
The difference between the analysis results of laboratories shall not be greater than the allowable difference listed in Table 2. Table 2
0. 001 5 ~ 0. 004 0
≥0. 004 0~0. 010
20. 010~0. 025
>0. 025~ 0. 050
>0. 050~0.10
>0.10~0. 30
>0.30~0.50
Part II Method 2 Determination of Iron Content by Potassium Dichromate Titration 9 Scope
This standard specifies the method for determining the iron content in copper and copper alloys. This standard is applicable to the determination of the iron content in copper and copper alloys. Determination range: ≥0.50%～7.00%. Difference
10 Referenced Standards
GB/T 5121.9--1996
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards are subject to revision, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB1.4-88 Guidelines for Standardization Work Provisions for the Preparation of Chemical Analysis Methods GB1467…78 General Principles and General Provisions for Chemical Analysis Methods for Metallurgical Products 11 Method Summary
The sample is dissolved in hydrochloric acid and nitric acid, and iron is precipitated in an ammonia solution. After the precipitate is dissolved in hydrochloric acid, sodium tungstate is used as an indicator, and titanium trichloride is used to reduce iron (II) to iron (I). Sodium diphenylamine sulfonate is used as an indicator and titrated with potassium dichromate standard titration solution. 12 Reagents
12.1 Ammonium chloride.
12.2 Hydrofluoric acid (o1.13 g/mL).
12.3 Perchloric acid (pl.67 g/ml.).
12.4 Hydrobromic acid (pl.49 g/ml.).
12.5 Ammonia water (o0.90 g/ml).
12.6 Hydrogen peroxide (30%).
12.7 Nitric acid (1+1).
12.8 Hydrochloric acid (1+1),
12.9 Sulfuric acid (1+1).
0 Ammonia water (1+99).
12.11 Mixed acid: Add 150mL sulfuric acid (pl.84g/mlL) and 200mL phosphoric acid (pl.69g/ml) to 650mL water while stirring, and mix well.
12.12 Aluminum solution (1.000g/L): Weigh 1.000g of pure aluminum (iron content not more than 0.003%) and place it in a 250mL beaker, add 50mL sodium hydroxide solution (50g/L), and heat to dissolve it. Neutralize with hydrochloric acid until the generated precipitate is dissolved and the excess is 10mL, and cool. Transfer to a 1000mL volumetric flask, dilute to the scale with water, and mix well. 12.13 Titanium trichloride solution: Take titanium trichloride solution (15%-20%), dilute 10 times with hydrochloric acid (1+9), and mix. Prepare it when needed. 12.14 Ammonium ferrous sulfate solution (5g/IL): Weigh 5g ammonium ferrous sulfate [(NH4), Fe(SO,)2·6H,O], dissolve it with sulfuric acid (5+95) and dilute it to 1000mL, and mix it.
12.15 Sodium tungstate solution (100g/L): Weigh 10g sodium tungstate (NaWO, 2HO), place it in a 150mL beaker, add 70mL water to dissolve it, filter it if there is precipitation, add 5mL phosphoric acid (p1.69g/mL), dilute it with water to 100mL, and mix it. 12.16 Sodium diphenylamine sulfonate solution (2g/L). 12.17 Potassium dichromate standard titration solution [(1/6K, Crz0,) = 0.01000mol/LJ: Weigh 0.4903g ​​of standard potassium dichromate that has been pre-dried to constant weight at 140~150℃ and cooled to room temperature in a desiccator, place it in a 250mL beaker and dissolve it in water. Transfer it to a 1000mL volumetric flask, dilute it to the mark with water, and mix it well. 13 Analysis steps
13.1 Test material
Weigh the sample according to Table 3, accurate to 0.0001g. 238
Iron content, %
>0.50~1.50
>1.50～4.00
>4. 00～7. 00
Carry out two independent determinations and take the average value. 13.2 Blank test
GB/T 5121. 9— 1996
Test material
In a blank test beaker, add 10mL of aluminum solution as a carrier, and perform a blank test with the test material to 13.3.6. Immediately add 10mL of mixed acid, 2.00mL of ammonium ferrous sulfate solution, and 3 drops of sodium diphenylamine sulfonate solution, and titrate with potassium dichromate standard titration solution until the solution presents a stable purple color as the end point, and record the volume V1 of the potassium dichromate standard titration solution consumed. Add 2.00 ml of ammonium ferrous sulfate solution, and then titrate with potassium dichromate standard titration solution to the endpoint, and record the volume V2 of potassium dichromate standard titration solution consumed. 13.3 Determination
13.3.1 Place the sample (13.1) in a 400 ml beaker, add 5 ml hydrochloric acid and 10 ml nitric acid, cover with Table III, heat to dissolve, boil to remove nitrogen oxides, wash the table and the cup wall with water, and dilute the volume with water to about 200 ml [When analyzing samples with silicon as the main component, place the sample (13.1) in a 300 ml polytetrafluoroethylene cup, add 5 ml hydrochloric acid and 10 ml nitric acid, heat to dissolve on a low temperature electric furnace, add 3 ml hydrofluoric acid and 5 ml perchloric acid, evaporate until thick white smoke is emitted, and cool. Add 20 ml hydrochloric acid, wait for the salts to dissolve, transfer the solution to a 400 ml beaker, and dilute the volume with water to about 200 ml]. 13.3.2 Add 3g of ammonium chloride, neutralize with nitrogen water (12.5) until all copper ions are converted into copper ammonia complex ions (neutralize the blank solution until aluminum hydroxide precipitates appear), and then add 5mL in excess. Boil for 1min, let stand for 5min, and filter. Wash the beaker 3 times with ammonia water (12.10), wash the precipitate 3 to 5 times, and discard the filtrate.
13.3.3 Wash the precipitate into the original beaker with water, and dissolve the residual precipitate on the filter paper in the original beaker with 20mL hot hydrochloric acid to which a few drops of hydrogen peroxide have been added. Wash the filter paper 4 times with hot water, and add the washing liquid to the main solution. When the arsenic is not less than 0.5mg or not less than 0.1mg, add 5mL nitric acid and 5mL sulfuric acid, heat and evaporate until white smoke appears, and cool slightly. Add 10mL hydrobromic acid, heat and evaporate until thick white smoke appears for 23min, and cool slightly. Add 5mL hydrobromic acid and 5mL sulfuric acid for treatment again, and cool. Add 20ml hydrochloric acid and a few drops of hydrogen peroxide. 13.3.4 Cover the table blood, heat and boil to destroy the hydrogen peroxide, and boil until the solution is transparent, dilute with water to 200ml, and then perform precipitation separation again according to the steps in 13.3.2. 13.3.5 When the iron content in aluminum bronze is greater than 0.50% to 1.50%, it is necessary to perform precipitation separation for the third time according to 13.3.3 and 13.3.4. 13.3.6 Wash the precipitate with water into the original beaker, and dissolve the residual precipitate on the filter paper in the original beaker with 20ml hot hydrochloric acid with a few drops of hydrogen peroxide. Wash the filter paper with hot water 4 times, add the washing liquid to the main solution, cover the table dish, heat and boil to destroy the hydrogen peroxide and boil until the solution is transparent, and cool. Wash the table blood and the wall of the cup with water, and remove table III. 13.3.7 Dilute the volume to about 130mL with water, add 1mL sodium tungstate solution, add titanium trichloride solution until a stable blue color appears, and slowly titrate with potassium dichromate standard titration solution until the blue color disappears. Do not record the number of milliliters. 13.3.8 Immediately add 10mL of mixed acid and three drops of sodium diphenylamine sulfonate solution, and titrate with potassium dichromate standard titration solution until a stable purple color appears as the end point.
14 Expression of analysis results
Calculate the percentage of iron according to formula (2):
Fe(%) = V- (V/- V2)1× 0. 055 85 × 100mc
Wherein: c—actual concentration of potassium dichromate standard titration solution, mol/L; V—volume of potassium dichromate standard titration solution consumed when titrating the sample solution, mL*(2)
GB/T5121.9—1996
V.—volume of potassium dichromate standard titration solution consumed when titrating the blank solution for the first time, ml. V2—volume of potassium dichromate standard titration solution consumed when titrating the blank solution for the second time, ml; mo
mass of the sample, g+
0.05585—mass of iron equivalent to 1.00ml potassium dichromate standard titration solution [c1/6K,Cr2O,）=1.000mol/L] g/mol.
The result is expressed to two decimal places.
15 Allowable difference
The difference between the analysis results of laboratories should not be greater than the allowable difference listed in Table 4. Table 4
>0.501.50
>1.50~4.00
>4. 00~7. 009--1996
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards are subject to revision, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB1.4-88 Standardization work guidelines for the preparation of chemical analysis methods GB1467…78 General principles and general provisions for chemical analysis methods for metallurgical products 11 Method summary
The sample is dissolved in hydrochloric acid and nitric acid, and iron is precipitated in an ammonia solution. After the precipitate is dissolved in hydrochloric acid, sodium tungstate is used as an indicator, and titanium trichloride is used to reduce iron (II) to iron (I). Sodium diphenylamine sulfonate is used as an indicator and titrated with potassium dichromate standard titration solution. 12 Reagents
12.1 Ammonium chloride.
12.2 Hydrofluoric acid (o1.13g/mL).
12.3 Perchloric acid (pl.67g/ml.).
12.4 Hydrobromic acid (pl.49g/ml.).
12.5 Ammonia water (o0.90g/ml).
12.6 Hydrogen peroxide (30%).
12.7 Nitric acid (1+1).
12.8 Hydrochloric acid (1+1),
12.9 Sulfuric acid (1+1).
0 Ammonia water (1+99).
12.11 Mixed acid: Add 150mL sulfuric acid (pl.84g/mlL) and 200mL phosphoric acid (pl.69g/ml) to 650mL water while stirring, and mix well.
12.12 Aluminum solution (1.000g/L): Weigh 1.000g of pure aluminum (iron content not more than 0.003%) and place it in a 250mL beaker, add 50mL of sodium hydroxide solution (50g/L), and heat to dissolve it. Neutralize with hydrochloric acid until the generated precipitate is dissolved and the excess is 10mL, and cool. Transfer to a 1000mL volumetric flask, dilute to the scale with water, and mix well. 12.13 Titanium trichloride solution: Take titanium trichloride solution (15%~20%), dilute 10 times with hydrochloric acid (1+9), and mix. Prepare it when needed. 12.14 Ammonium ferrous sulfate solution (5g/IL): Weigh 5g of ammonium ferrous sulfate [(NH4), Fe(SO,)2·6H,O], dissolve it with sulfuric acid (5+95) and dilute to 1000mL, and mix well.
12.15 Sodium tungstate solution (100g/L): Weigh 10g sodium tungstate (NaWO, 2HO), place in a 150mL beaker, add 70mL water to dissolve, filter if there is precipitation, add 5mL phosphoric acid (p1.69g/mL), dilute to 100mL with water, and mix. 12.16 Sodium diphenylamine sulfonate solution (2g/L). 12.17 Potassium dichromate standard titration solution [(1/6K, Crz0,) = 0.01000mol/LJ: Weigh 0.4903g ​​of standard potassium dichromate that has been pre-dried at 140~150℃ to constant weight, placed in a desiccator and cooled to room temperature, place in a 250mL beaker, and dissolve in water. Transfer to a 1000mL volumetric flask, dilute to scale with water, and mix. 13 Analysis steps
13.1 Test material
Weigh the sample according to Table 3, accurate to 0.0001g. 238
Iron content, %
>0.50~1.50
>1.50～4.00
>4. 00～7. 00
Carry out two independent determinations and take the average value. 13.2 Blank test
GB/T 5121. 9— 1996
Test material
In a blank test beaker, add 10mL of aluminum solution as a carrier, and perform a blank test together with the test material to 13.3.6. Immediately add 10 mL of mixed acid, 2.00 mL of ammonium ferrous sulfate solution, and 3 drops of sodium diphenylamine sulfonate solution, and titrate with potassium dichromate standard titration solution until the solution turns a stable purple color, which is the end point. Record the volume V1 of potassium dichromate standard titration solution consumed. Add 2.00 ml of ammonium ferrous sulfate solution, and then titrate with potassium dichromate standard titration solution to the endpoint, and record the volume V2 of potassium dichromate standard titration solution consumed. 13.3 Determination
13.3.1 Place the sample (13.1) in a 400 ml beaker, add 5 ml hydrochloric acid and 10 ml nitric acid, cover with Table III, heat to dissolve, boil to remove nitrogen oxides, wash the table and the cup wall with water, and dilute the volume with water to about 200 ml [When analyzing samples with silicon as the main component, place the sample (13.1) in a 300 ml polytetrafluoroethylene cup, add 5 ml hydrochloric acid and 10 ml nitric acid, heat to dissolve on a low temperature electric furnace, add 3 ml hydrofluoric acid and 5 ml perchloric acid, evaporate until thick white smoke is emitted, and cool. Add 20 ml hydrochloric acid, wait for the salts to dissolve, transfer the solution to a 400 ml beaker, and dilute the volume with water to about 200 ml]. 13.3.2 Add 3g of ammonium chloride, neutralize with nitrogen water (12.5) until all copper ions are converted into copper ammonia complex ions (neutralize the blank solution until aluminum hydroxide precipitates appear), and then add 5mL in excess. Boil for 1min, let stand for 5min, and filter. Wash the beaker 3 times with ammonia water (12.10), wash the precipitate 3 to 5 times, and discard the filtrate.
13.3.3 Wash the precipitate into the original beaker with water, and dissolve the residual precipitate on the filter paper in the original beaker with 20mL hot hydrochloric acid to which a few drops of hydrogen peroxide have been added. Wash the filter paper 4 times with hot water, and add the washing liquid to the main solution. When the arsenic is not less than 0.5mg or not less than 0.1mg, add 5mL nitric acid and 5mL sulfuric acid, heat and evaporate until white smoke appears, and cool slightly. Add 10mL hydrobromic acid, heat and evaporate until thick white smoke appears for 23min, and cool slightly. Add 5mL hydrobromic acid and 5mL sulfuric acid for treatment again, and cool. Add 20ml hydrochloric acid and a few drops of hydrogen peroxide. 13.3.4 Cover the table blood, heat and boil to destroy the hydrogen peroxide, and boil until the solution is transparent, dilute with water to 200ml, and then perform precipitation separation again according to the steps in 13.3.2. 13.3.5 When the iron content in aluminum bronze is greater than 0.50% to 1.50%, it is necessary to perform precipitation separation for the third time according to 13.3.3 and 13.3.4. 13.3.6 Wash the precipitate with water into the original beaker, and dissolve the residual precipitate on the filter paper in the original beaker with 20ml hot hydrochloric acid with a few drops of hydrogen peroxide. Wash the filter paper with hot water 4 times, add the washing liquid to the main solution, cover the table dish, heat and boil to destroy the hydrogen peroxide and boil until the solution is transparent, and cool. Wash the table blood and the wall of the cup with water, and remove table III. 13.3.7 Dilute the volume to about 130mL with water, add 1mL sodium tungstate solution, add titanium trichloride solution until a stable blue color appears, and slowly titrate with potassium dichromate standard titration solution until the blue color disappears. Do not record the number of milliliters. 13.3.8 Immediately add 10mL of mixed acid and three drops of sodium diphenylamine sulfonate solution, and titrate with potassium dichromate standard titration solution until a stable purple color appears as the end point.
14 Expression of analysis results
Calculate the percentage of iron according to formula (2):
Fe(%) = V- (V/- V2)1× 0. 055 85 × 100mc
Wherein: c—actual concentration of potassium dichromate standard titration solution, mol/L; V—volume of potassium dichromate standard titration solution consumed when titrating the sample solution, mL*(2)
GB/T5121.9—1996
V.—volume of potassium dichromate standard titration solution consumed when titrating the blank solution for the first time, ml. V2—volume of potassium dichromate standard titration solution consumed when titrating the blank solution for the second time, ml; mo
mass of the sample, g+
0.05585—mass of iron equivalent to 1.00ml potassium dichromate standard titration solution [c1/6K,Cr2O,）=1.000mol/L] g/mol.
The result is expressed to two decimal places.
15 Allowable difference
The difference between the analysis results of laboratories should not be greater than the allowable difference listed in Table 4. Table 4
>0.501.50
>1.50~4.00
>4. 00~7. 009--1996
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards are subject to revision, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB1.4-88 Standardization work guidelines for the preparation of chemical analysis methods GB1467…78 General principles and general provisions for chemical analysis methods for metallurgical products 11 Method summary
The sample is dissolved in hydrochloric acid and nitric acid, and iron is precipitated in an ammonia solution. After the precipitate is dissolved in hydrochloric acid, sodium tungstate is used as an indicator, and titanium trichloride is used to reduce iron (II) to iron (I). Sodium diphenylamine sulfonate is used as an indicator and titrated with potassium dichromate standard titration solution. 12 Reagents
12.1 Ammonium chloride.
12.2 Hydrofluoric acid (o1.13g/mL). bZxz.net
12.3 Perchloric acid (pl.67g/ml.).
12.4 Hydrobromic acid (pl.49g/ml.).
12.5 Ammonia water (o0.90g/ml).
12.6 Hydrogen peroxide (30%).
12.7 Nitric acid (1+1).
12.8 Hydrochloric acid (1+1),
12.9 Sulfuric acid (1+1).
0 Ammonia water (1+99).
12.11 Mixed acid: Add 150mL sulfuric acid (pl.84g/mlL) and 200mL phosphoric acid (pl.69g/ml) to 650mL water while stirring, and mix well.
12.12 Aluminum solution (1.000g/L): Weigh 1.000g of pure aluminum (iron content not more than 0.003%) and place it in a 250mL beaker, add 50mL of sodium hydroxide solution (50g/L), and heat to dissolve it. Neutralize with hydrochloric acid until the generated precipitate is dissolved and the excess is 10mL, and cool. Transfer to a 1000mL volumetric flask, dilute to the scale with water, and mix well. 12.13 Titanium trichloride solution: Take titanium trichloride solution (15%~20%), dilute 10 times with hydrochloric acid (1+9), and mix. Prepare it when needed. 12.14 Ammonium ferrous sulfate solution (5g/IL): Weigh 5g of ammonium ferrous sulfate [(NH4), Fe(SO,)2·6H,O], dissolve it with sulfuric acid (5+95) and dilute to 1000mL, and mix well.
12.15 Sodium tungstate solution (100g/L): Weigh 10g sodium tungstate (NaWO, 2HO), place in a 150mL beaker, add 70mL water to dissolve, filter if there is precipitation, add 5mL phosphoric acid (p1.69g/mL), dilute to 100mL with water, and mix. 12.16 Sodium diphenylamine sulfonate solution (2g/L). 12.17 Potassium dichromate standard titration solution [(1/6K, Crz0,) = 0.01000mol/LJ: Weigh 0.4903g ​​of standard potassium dichromate that has been pre-dried at 140~150℃ to constant weight, placed in a desiccator and cooled to room temperature, place in a 250mL beaker, and dissolve in water. Transfer to a 1000mL volumetric flask, dilute to scale with water, and mix. 13 Analysis steps
13.1 Test material
Weigh the sample according to Table 3, accurate to 0.0001g. 238
Iron content, %
>0.50~1.50
>1.50～4.00
>4. 00～7. 00
Carry out two independent determinations and take the average value. 13.2 Blank test
GB/T 5121. 9— 1996
Test material
In a blank test beaker, add 10mL of aluminum solution as a carrier, and perform a blank test together with the test material to 13.3.6. Immediately add 10 mL of mixed acid, 2.00 mL of ammonium ferrous sulfate solution, and 3 drops of sodium diphenylamine sulfonate solution, and titrate with potassium dichromate standard titration solution until the solution turns a stable purple color, which is the end point. Record the volume V1 of potassium dichromate standard titration solution consumed. Add 2.00 ml of ammonium ferrous sulfate solution, and then titrate with potassium dichromate standard titration solution to the endpoint, and record the volume V2 of potassium dichromate standard titration solution consumed. 13.3 Determination
13.3.1 Place the sample (13.1) in a 400 ml beaker, add 5 ml hydrochloric acid and 10 ml nitric acid, cover with Table III, heat to dissolve, boil to remove nitrogen oxides, wash the table and the cup wall with water, and dilute the volume with water to about 200 ml [When analyzing samples with silicon as the main component, place the sample (13.1) in a 300 ml polytetrafluoroethylene cup, add 5 ml hydrochloric acid and 10 ml nitric acid, heat to dissolve on a low temperature electric furnace, add 3 ml hydrofluoric acid and 5 ml perchloric acid, evaporate until thick white smoke is emitted, and cool. Add 20 ml hydrochloric acid, wait for the salts to dissolve, transfer the solution to a 400 ml beaker, and dilute the volume with water to about 200 ml]. 13.3.2 Add 3g of ammonium chloride, neutralize with nitrogen water (12.5) until all copper ions are converted into copper ammonia complex ions (neutralize the blank solution until aluminum hydroxide precipitates appear), and then add 5mL in excess. Boil for 1min, let stand for 5min, and filter. Wash the beaker 3 times with ammonia water (12.10), wash the precipitate 3 to 5 times, and discard the filtrate.
13.3.3 Wash the precipitate into the original beaker with water, and dissolve the residual precipitate on the filter paper in the original beaker with 20mL hot hydrochloric acid to which a few drops of hydrogen peroxide have been added. Wash the filter paper 4 times with hot water, and add the washing liquid to the main solution. When the arsenic is not less than 0.5mg or not less than 0.1mg, add 5mL nitric acid and 5mL sulfuric acid, heat and evaporate until white smoke appears, and cool slightly. Add 10mL hydrobromic acid, heat and evaporate until thick white smoke appears for 23min, and cool slightly. Add 5mL hydrobromic acid and 5mL sulfuric acid for treatment again, and cool. Add 20ml hydrochloric acid and a few drops of hydrogen peroxide. 13.3.4 Cover the table blood, heat and boil to destroy the hydrogen peroxide, and boil until the solution is transparent, dilute with water to 200ml, and then perform precipitation separation again according to the steps in 13.3.2. 13.3.5 When the iron content in aluminum bronze is greater than 0.50% to 1.50%, it is necessary to perform precipitation separation for the third time according to 13.3.3 and 13.3.4. 13.3.6 Wash the precipitate with water into the original beaker, and dissolve the residual precipitate on the filter paper in the original beaker with 20ml hot hydrochloric acid with a few drops of hydrogen peroxide. Wash the filter paper with hot water 4 times, add the washing liquid to the main solution, cover the table dish, heat and boil to destroy the hydrogen peroxide and boil until the solution is transparent, and cool. Wash the table blood and the wall of the cup with water, and remove table III. 13.3.7 Dilute the volume to about 130mL with water, add 1mL sodium tungstate solution, add titanium trichloride solution until a stable blue color appears, and slowly titrate with potassium dichromate standard titration solution until the blue color disappears. Do not record the number of milliliters. 13.3.8 Immediately add 10mL of mixed acid and three drops of sodium diphenylamine sulfonate solution, and titrate with potassium dichromate standard titration solution until a stable purple color appears as the end point.
14 Expression of analysis results
Calculate the percentage of iron according to formula (2):
Fe(%) = V- (V/- V2)1× 0. 055 85 × 100mc
Wherein: c—actual concentration of potassium dichromate standard titration solution, mol/L; V—volume of potassium dichromate standard titration solution consumed when titrating the sample solution, mL*(2)
GB/T5121.9—1996
V.—volume of potassium dichromate standard titration solution consumed when titrating the blank solution for the first time, ml. V2—volume of potassium dichromate standard titration solution consumed when titrating the blank solution for the second time, ml; mo
mass of the sample, g+
0.05585—mass of iron equivalent to 1.00ml potassium dichromate standard titration solution [c1/6K,Cr2O,）=1.000mol/L] g/mol.
The result is expressed to two decimal places.
15 Allowable difference
The difference between the analysis results of laboratories should not be greater than the allowable difference listed in Table 4. Table 4
>0.501.50
>1.50~4.00
>4. 00~7. 005 Ammonia water (o0.90g/ml).
12.6 Hydrogen peroxide (30%).
12.7 Nitric acid (1+1).
12.8 Hydrochloric acid (1+1),
12.9 Sulfuric acid (1+1).
0 Ammonia water (1+99).
12.11 Mixed acid: Add 150mL sulfuric acid (pl.84g/mlL) and 200mL phosphoric acid (pl.69g/ml) to 650mL water while stirring, and mix well.
12.12 Aluminum solution (1.000g/L): Weigh 1.000g of pure aluminum (iron content not more than 0.003%) and place it in a 250mL beaker, add 50mL sodium hydroxide solution (50g/L), and heat to dissolve it. Neutralize with hydrochloric acid until the generated precipitate is dissolved and the excess is 10mL, and cool. Transfer to a 1000mL volumetric flask, dilute to the mark with water, and mix. 12.13 Titanium trichloride solution: Take titanium trichloride solution (15%-20%), dilute 10 times with hydrochloric acid (1+9), and mix. Prepare it when needed. 12.14 Ammonium ferrous sulfate solution (5g/IL): Weigh 5g of ammonium ferrous sulfate [(NH4), Fe(SO,)2·6H,O], dissolve it with sulfuric acid (5+95) and dilute to 1000mL, and mix.
12.15 Sodium tungstate solution (100g/L): Weigh 10g of sodium tungstate (NaWO, 2HO), place it in a 150mL beaker, add 70mL of water to dissolve, filter if there is precipitation, add 5mL of phosphoric acid (p1.69g/mL), dilute to 100mL with water, and mix. 12.16 Sodium diphenylamine sulfonate solution (2g/L). 12.17 Potassium dichromate standard titration solution [(1/6K, Crz0,) = 0.01000mol/LJ: Weigh 0.4903g ​​of standard potassium dichromate that has been pre-dried to constant weight at 140~150℃ and cooled to room temperature in a desiccator, place it in a 250mL beaker and dissolve it in water. Transfer it to a 1000mL volumetric flask, dilute it to the mark with water, and mix it well. 13 Analysis steps
13.1 Test material
Weigh the sample according to Table 3, accurate to 0.0001g. 238
Iron content, %
>0.50~1.50
>1.50～4.00
>4. 00～7. 00
Carry out two independent determinations and take the average value. 13.2 Blank test
GB/T 5121. 9— 1996
Test material
In a blank test beaker, add 10mL of aluminum solution as a carrier, and perform a blank test with the test material to 13.3.6. Immediately add 10mL of mixed acid, 2.00mL of ammonium ferrous sulfate solution, and 3 drops of sodium diphenylamine sulfonate solution, and titrate with potassium dichromate standard titration solution until the solution presents a stable purple color as the end point, and record the volume V1 of the potassium dichromate standard titration solution consumed. Add 2.00 ml of ammonium ferrous sulfate solution, and then titrate with potassium dichromate standard titration solution to the endpoint, and record the volume V2 of potassium dichromate standard titration solution consumed. 13.3 Determination
13.3.1 Place the sample (13.1) in a 400 ml beaker, add 5 ml hydrochloric acid and 10 ml nitric acid, cover with Table III, heat to dissolve, boil to remove nitrogen oxides, wash the table and the cup wall with water, and dilute the volume with water to about 200 ml [When analyzing samples with silicon as the main component, place the sample (13.1) in a 300 ml polytetrafluoroethylene cup, add 5 ml hydrochloric acid and 10 ml nitric acid, heat to dissolve on a low temperature electric furnace, add 3 ml hydrofluoric acid and 5 ml perchloric acid, evaporate until thick white smoke is emitted, and cool. Add 20 ml hydrochloric acid, wait for the salts to dissolve, transfer the solution to a 400 ml beaker, and dilute the volume with water to about 200 ml]. 13.3.2 Add 3g of ammonium chloride, neutralize with nitrogen water (12.5) until all copper ions are converted into copper ammonia complex ions (neutralize the blank solution until aluminum hydroxide precipitates appear), and then add 5mL in excess. Boil for 1min, let stand for 5min, and filter. Wash the beaker 3 times with ammonia water (12.10), wash the precipitate 3 to 5 times, and discard the filtrate.
13.3.3 Wash the precipitate into the original beaker with water, and dissolve the residual precipitate on the filter paper in the original beaker with 20mL hot hydrochloric acid to which a few drops of hydrogen peroxide have been added. Wash the filter paper 4 times with hot water, and add the washing liquid to the main solution. When the arsenic is not less than 0.5mg or not less than 0.1mg, add 5mL nitric acid and 5mL sulfuric acid, heat and evaporate until white smoke appears, and cool slightly. Add 10mL hydrobromic acid, heat and evaporate until thick white smoke appears for 23min, and cool slightly. Add 5mL hydrobromic acid and 5mL sulfuric acid for treatment again, and cool. Add 20ml hydrochloric acid and a few drops of hydrogen peroxide. 13.3.4 Cover the table blood, heat and boil to destroy the hydrogen peroxide, and boil until the solution is transparent, dilute with water to 200ml, and then perform precipitation separation again according to the steps in 13.3.2. 13.3.5 When the iron content in aluminum bronze is greater than 0.50% to 1.50%, it is necessary to perform precipitation separation for the third time according to 13.3.3 and 13.3.4. 13.3.6 Wash the precipitate with water into the original beaker, and dissolve the residual precipitate on the filter paper in the original beaker with 20ml hot hydrochloric acid with a few drops of hydrogen peroxide. Wash the filter paper with hot water 4 times, add the washing liquid to the main solution, cover the table dish, heat and boil to destroy the hydrogen peroxide and boil until the solution is transparent, and cool. Wash the table blood and the wall of the cup with water, and remove table III. 13.3.7 Dilute the volume to about 130mL with water, add 1mL sodium tungstate solution, add titanium trichloride solution until a stable blue color appears, and slowly titrate with potassium dichromate standard titration solution until the blue color disappears. Do not record the number of milliliters. 13.3.8 Immediately add 10mL of mixed acid and three drops of sodium diphenylamine sulfonate solution, and titrate with potassium dichromate standard titration solution until a stable purple color appears as the end point.
14 Expression of analysis results
Calculate the percentage of iron according to formula (2):
Fe(%) = V- (V/- V2)1× 0. 055 85 × 100mc
Wherein: c—actual concentration of potassium dichromate standard titration solution, mol/L; V—volume of potassium dichromate standard titration solution consumed when titrating the sample solution, mL*(2)
GB/T5121.9—1996
V.—volume of potassium dichromate standard titration solution consumed when titrating the blank solution for the first time, ml. V2—volume of potassium dichromate standard titration solution consumed when titrating the blank solution for the second time, ml; mo
mass of the sample, g+
0.05585—mass of iron equivalent to 1.00ml potassium dichromate standard titration solution [c1/6K,Cr2O,）=1.000mol/L] g/mol.
The result is expressed to two decimal places.
15 Allowable difference
The difference between the analysis results of laboratories should not be greater than the allowable difference listed in Table 4. Table 4
>0.501.50
>1.50~4.00
>4. 00~7. 005 Ammonia water (o0.90g/ml).
12.6 Hydrogen peroxide (30%).
12.7 Nitric acid (1+1).
12.8 Hydrochloric acid (1+1),
12.9 Sulfuric acid (1+1).
0 Ammonia water (1+99).
12.11 Mixed acid: Add 150mL sulfuric acid (pl.84g/mlL) and 200mL phosphoric acid (pl.69g/ml) to 650mL water while stirring, and mix well.
12.12 Aluminum solution (1.000g/L): Weigh 1.000g of pure aluminum (iron content not more than 0.003%) and place it in a 250mL beaker, add 50mL sodium hydroxide solution (50g/L), and heat to dissolve it. Neutralize with hydrochloric acid until the generated precipitate is dissolved and the excess is 10mL, and cool. Transfer to a 1000mL volumetric flask, dilute to the mark with water, and mix. 12.13 Titanium trichloride solution: Take titanium trichloride solution (15%-20%), dilute 10 times with hydrochloric acid (1+9), and mix. Prepare it when needed. 12.14 Ammonium ferrous sulfate solution (5g/IL): Weigh 5g of ammonium ferrous sulfate [(NH4), Fe(SO,)2·6H,O], dissolve it with sulfuric acid (5+95) and dilute to 1000mL, and mix.
12.15 Sodium tungstate solution (100g/L): Weigh 10g of sodium tungstate (NaWO, 2HO), place it in a 150mL beaker, add 70mL of water to dissolve, filter if there is precipitation, add 5mL of phosphoric acid (p1.69g/mL), dilute to 100mL with water, and mix. 12.16 Sodium diphenylamine sulfonate solution (2g/L). 12.17 Potassium dichromate standard titration solution [(1/6K, Crz0,) = 0.01000mol/LJ: Weigh 0.4903g ​​of standard potassium dichromate that has been pre-dried to constant weight at 140~150℃ and cooled to room temperature in a desiccator, place it in a 250mL beaker and dissolve it in water. Transfer it to a 1000mL volumetric flask, dilute it to the mark with water, and mix it well. 13 Analysis steps
13.1 Test material
Weigh the sample according to Table 3, accurate to 0.0001g. 238
Iron content, %
>0.50~1.50
>1.50～4.00
>4. 00～7. 00
Carry out two independent determinations and take the average value. 13.2 Blank test
GB/T 5121. 9— 1996
Test material
In a blank test beaker, add 10mL of aluminum solution as a carrier, and perform a blank test with the test material to 13.3.6. Immediately add 10mL of mixed acid, 2.00mL of ammonium ferrous sulfate solution, and 3 drops of sodium diphenylamine sulfonate solution, and titrate with potassium dichromate standard titration solution until the solution presents a stable purple color as the end point, and record the volume V1 of the potassium dichromate standard titration solution consumed. Add 2.00 ml of ammonium ferrous sulfate solution, and then titrate with potassium dichromate standard titration solution to the endpoint, and record the volume V2 of potassium dichromate standard titration solution consumed. 13.3 Determination
13.3.1 Place the sample (13.1) in a 400 ml beaker, add 5 ml hydrochloric acid and 10 ml nitric acid, cover with Table III, heat to dissolve, boil to remove nitrogen oxides, wash the table and the cup wall with water, and dilute the volume with water to about 200 ml [When analyzing samples with silicon as the main component, place the sample (13.1) in a 300 ml polytetrafluoroethylene cup, add 5 ml hydrochloric acid and 10 ml nitric acid, heat to dissolve on a low temperature electric furnace, add 3 ml hydrofluoric acid and 5 ml perchloric acid, evaporate until thick white smoke is emitted, and cool. Add 20 ml hydrochloric acid, wait for the salts to dissolve, transfer the solution to a 400 ml beaker, and dilute the volume with water to about 200 ml]. 13.3.2 Add 3g of ammonium chloride, neutralize with nitrogen water (12.5) until all copper ions are converted into copper ammonia complex ions (neutralize the blank solution until aluminum hydroxide precipitates appear), and then add 5mL in excess. Boil for 1min, let stand for 5min, and filter. Wash the beaker 3 times with ammonia water (12.10), wash the precipitate 3 to 5 times, and discard the filtrate.
13.3.3 Wash the precipitate into the original beaker with water, and dissolve the residual precipitate on the filter paper in the original beaker with 20mL hot hydrochloric acid to which a few drops of hydrogen peroxide have been added. Wash the filter paper 4 times with hot water, and add the washing liquid to the main solution. When the arsenic is not less than 0.5mg or not less than 0.1mg, add 5mL nitric acid and 5mL sulfuric acid, heat and evaporate until white smoke appears, and cool slightly. Add 10mL hydrobromic acid, heat and evaporate until thick white smoke appears for 23min, and cool slightly. Add 5mL hydrobromic acid and 5mL sulfuric acid for treatment again, and cool. Add 20ml hydrochloric acid and a few drops of hydrogen peroxide. 13.3.4 Cover the table blood, heat and boil to destroy the hydrogen peroxide, and boil until the solution is transparent, dilute with water to 200ml, and then perform precipitation separation again according to the steps in 13.3.2. 13.3.5 When the iron content in aluminum bronze is greater than 0.50% to 1.50%, it is necessary to perform precipitation separation for the third time according to 13.3.3 and 13.3.4. 13.3.6 Wash the precipitate with water into the original beaker, and dissolve the residual precipitate on the filter paper in the original beaker with 20ml hot hydrochloric acid with a few drops of hydrogen peroxide. Wash the filter paper with hot water 4 times, add the washing liquid to the main solution, cover the table dish, heat and boil to destroy the hydrogen peroxide and boil until the solution is transparent, and cool. Wash the table blood and the wall of the cup with water, and remove table III. 13.3.7 Dilute the volume to about 130mL with water, add 1mL sodium tungstate solution, add titanium trichloride solution until a stable blue color appears, and slowly titrate with potassium dichromate standard titration solution until the blue color disappears. Do not record the number of milliliters. 13.3.8 Immediately add 10mL of mixed acid and three drops of sodium diphenylamine sulfonate solution, and titrate with potassium dichromate standard titration solution until a stable purple color appears as the end point.
14 Expression of analysis results
Calculate the percentage of iron according to formula (2):
Fe(%) = V- (V/- V2)1× 0. 055 85 × 100mc
Wherein: c—actual concentration of potassium dichromate standard titration solution, mol/L; V—volume of potassium dichromate standard titration solution consumed when titrating the sample solution, mL*(2)
GB/T5121.9—1996
V.—volume of potassium dichromate standard titration solution consumed when titrating the blank solution for the first time, ml. V2—volume of potassium dichromate standard titration solution consumed when titrating the blank solution for the second time, ml; mo
mass of the sample, g+
0.05585—mass of iron equivalent to 1.00ml potassium dichromate standard titration solution [c1/6K,Cr2O,）=1.000mol/L] g/mol.
The result is expressed to two decimal places.
15 Allowable difference
The difference between the analysis results of laboratories should not be greater than the allowable difference listed in Table 4. Table 4
>0.501.50
>1.50~4.00
>4. 00~7. 0001000mol/LJ: Weigh 0.4903g ​​of standard potassium dichromate that has been dried to constant weight at 140~150℃ and cooled to room temperature in a desiccator, place it in a 250mL beaker and dissolve it in water. Transfer it to a 1000mL volumetric flask, dilute it to the mark with water, and mix it well. 13 Analysis steps
13.1 Test material
Weigh the sample according to Table 3, accurate to 0.0001g. 238
Iron content, %
>0.50~1.50
>1.50～4.00
>4. 00～7. 00
Carry out two independent determinations and take the average value. 13.2 Blank test
GB/T 5121. 9— 1996
Test material
In a blank test beaker, add 10mL of aluminum solution as a carrier, and perform a blank test with the test material to 13.3.6. Immediately add 10mL of mixed acid, 2.00mL of ammonium ferrous sulfate solution, and 3 drops of sodium diphenylamine sulfonate solution, and titrate with potassium dichromate standard titration solution until the solution presents a stable purple color as the end point, and record the volume V1 of the potassium dichromate standard titration solution consumed. Add 2.00 ml of ammonium ferrous sulfate solution, and then titrate with potassium dichromate standard titration solution to the endpoint, and record the volume V2 of potassium dichromate standard titration solution consumed. 13.3 Determination
13.3.1 Place the sample (13.1) in a 400 ml beaker, add 5 ml hydrochloric acid and 10 ml nitric acid, cover with Table III, heat to dissolve, boil to remove nitrogen oxides, wash the table and the cup wall with water, and dilute the volume with water to about 200 ml [When analyzing samples with silicon as the main component, place the sample (13.1) in a 300 ml polytetrafluoroethylene cup, add 5 ml hydrochloric acid and 10 ml nitric acid, heat to dissolve on a low temperature electric furnace, add 3 ml hydrofluoric acid and 5 ml perchloric acid, evaporate until thick white smoke is emitted, and cool. Add 20 ml hydrochloric acid, wait for the salts to dissolve, transfer the solution to a 400 ml beaker, and dilute the volume with water to about 200 ml]. 13.3.2 Add 3g of ammonium chloride, neutralize with nitrogen water (12.5) until all copper ions are converted into copper ammonia complex ions (neutralize the blank solution until aluminum hydroxide precipitates appear), and then add 5mL in excess. Boil for 1min, let stand for 5min, and filter. Wash the beaker 3 times with ammonia water (12.10), wash the precipitate 3 to 5 times, and discard the filtrate.
13.3.3 Wash the precipitate into the original beaker with water, and dissolve the residual precipitate on the filter paper in the original beaker with 20mL hot hydrochloric acid to which a few drops of hydrogen peroxide have been added. Wash the filter paper 4 times with hot water, and add the washing liquid to the main solution. When the arsenic is not less than 0.5mg or not less than 0.1mg, add 5mL nitric acid and 5mL sulfuric acid, heat and evaporate until white smoke appears, and cool slightly. Add 10mL hydrobromic acid, heat and evaporate until thick white smoke appears for 23min, and cool slightly. Add 5mL hydrobromic acid and 5mL sulfuric acid for treatment again, and cool. Add 20ml hydrochloric acid and a few drops of hydrogen peroxide. 13.3.4 Cover the table blood, heat and boil to destroy the hydrogen peroxide, and boil until the solution is transparent, dilute with water to 200ml, and then perform precipitation separation again according to the steps in 13.3.2. 13.3.5 When the iron content in aluminum bronze is greater than 0.50% to 1.50%, it is necessary to perform precipitation separation for the third time according to 13.3.3 and 13.3.4. 13.3.6 Wash the precipitate with water into the original beaker, and dissolve the residual precipitate on the filter paper in the original beaker with 20ml hot hydrochloric acid with a few drops of hydrogen peroxide. Wash the filter paper with hot water 4 times, add the washing liquid to the main solution, cover the table dish, heat and boil to destroy the hydrogen peroxide and boil until the solution is transparent, and cool. Wash the table blood and the wall of the cup with water, and remove table III. 13.3.7 Dilute the volume to about 130mL with water, add 1mL sodium tungstate solution, add titanium trichloride solution until a stable blue color appears, and slowly titrate with potassium dichromate standard titration solution until the blue color disappears. Do not record the number of milliliters. 13.3.8 Immediately add 10mL of mixed acid and three drops of sodium diphenylamine sulfonate solution, and titrate with potassium dichromate standard titration solution until a stable purple color appears as the end point.
14 Expression of analysis results
Calculate the percentage of iron according to formula (2):
Fe(%) = V- (V/- V2)1× 0. 055 85 × 100mc
Wherein: c—actual concentration of potassium dichromate standard titration solution, mol/L; V—volume of potassium dichromate standard titration solution consumed when titrating the sample solution, mL*(2)
GB/T5121.9—1996
V.—volume of potassium dichromate standard titration solution consumed when titrating the blank solution for the first time, ml. V2—volume of potassium dichromate standard titration solution consumed when titrating the blank solution for the second time, ml; mo
mass of the sample, g+
0.05585—mass of iron equivalent to 1.00ml potassium dichromate standard titration solution [c1/6K,Cr2O,）=1.000mol/L] g/mol.
The result is expressed to two decimal places.
15 Allowable difference
The difference between the analysis results of laboratories should not be greater than the allowable difference listed in Table 4. Table 4
>0.501.50
>1.50~4.00
>4. 00~7. 0001000mol/LJ: Weigh 0.4903g ​​of standard potassium dichromate that has been dried to constant weight at 140~150℃ and cooled to room temperature in a desiccator, place it in a 250mL beaker and dissolve it in water. Transfer it to a 1000mL volumetric flask, dilute it to the mark with water, and mix it well. 13 Analysis steps
13.1 Test material
Weigh the sample according to Table 3, accurate to 0.0001g. 238
Iron content, %
>0.50~1.50
>1.50～4.00
>4. 00～7. 00
Carry out two independent determinations and take the average value. 13.2 Blank test
GB/T 5121. 9— 1996
Test material
In a blank test beaker, add 10mL of aluminum solution as a carrier, and perform a blank test with the test material to 13.3.6. Immediately add 10mL of mixed acid, 2.00mL of ammonium ferrous sulfate solution, and 3 drops of sodium diphenylamine sulfonate solution, and titrate with potassium dichromate standard titration solution until the solution presents a stable purple color as the end point, and record the volume V1 of the potassium dichromate standard titration solution consumed. Add 2.00 ml of ammonium ferrous sulfate solution, and then titrate with potassium dichromate standard titration solution to the endpoint, and record the volume V2 of potassium dichromate standard titration solution consumed. 13.3 Determination
13.3.1 Place the sample (13.1) in a 400 ml beaker, add 5 ml hydrochloric acid and 10 ml nitric acid, cover with Table III, heat to dissolve, boil to remove nitrogen oxides, wash the table and the cup wall with water, and dilute the volume with water to about 200 ml [When analyzing samples with silicon as the main component, place the sample (13.1) in a 300 ml polytetrafluoroethylene cup, add 5 ml hydrochloric acid and 10 ml nitric acid, heat to dissolve on a low temperature electric furnace, add 3 ml hydrofluoric acid and 5 ml perchloric acid, evaporate until thick white smoke is emitted, and cool. Add 20 ml hydrochloric acid, wait for the salts to dissolve, transfer the solution to a 400 ml beaker, and dilute the volume with water to about 200 ml]. 13.3.2 Add 3g of ammonium chloride, neutralize with nitrogen water (12.5) until all copper ions are converted into copper ammonia complex ions (neutralize the blank solution until aluminum hydroxide precipitates appear), and then add 5mL in excess. Boil for 1min, let stand for 5min, and filter. Wash the beaker 3 times with ammonia water (12.10), wash the precipitate 3 to 5 times, and discard the filtrate.
13.3.3 Wash the precipitate into the original beaker with water, and dissolve the residual precipitate on the filter paper in the original beaker with 20mL hot hydrochloric acid to which a few drops of hydrogen peroxide have been added. Wash the filter paper 4 times with hot water, and add the washing liquid to the main solution. When the arsenic is not less than 0.5mg or not less than 0.1mg, add 5mL nitric acid and 5mL sulfuric acid, heat and evaporate until white smoke appears, and cool slightly. Add 10mL hydrobromic acid, heat and evaporate until thick white smoke appears for 23min, and cool slightly. Add 5mL hydrobromic acid and 5mL sulfuric acid for treatment again, and cool. Add 20ml hydrochloric acid and a few drops of hydrogen peroxide. 13.3.4 Cover the table blood, heat and boil to destroy the hydrogen peroxide, and boil until the solution is transparent, dilute with water to 200ml, and then perform precipitation separation again according to the steps in 13.3.2. 13.3.5 When the iron content in aluminum bronze is greater than 0.50% to 1.50%, it is necessary to perform precipitation separation for the third time according to 13.3.3 and 13.3.4. 13.3.6 Wash the precipitate with water into the original beaker, and dissolve the residual precipitate on the filter paper in the original beaker with 20ml hot hydrochloric acid with a few drops of hydrogen peroxide. Wash the filter paper with hot water 4 times, add the washing liquid to the main solution, cover the table dish, heat and boil to destroy the hydrogen peroxide and boil until the solution is transparent, and cool. Wash the table blood and the wall of the cup with water, and remove table III. 13.3.7 Dilute the volume to about 130mL with water, add 1mL sodium tungstate solution, add titanium trichloride solution until a stable blue color appears, and slowly titrate with potassium dichromate standard titration solution until the blue color disappears. Do not record the number of milliliters. 13.3.8 Immediately add 10mL of mixed acid and three drops of sodium diphenylamine sulfonate solution, and titrate with potassium dichromate standard titration solution until a stable purple color appears as the end point.
14 Expression of analysis results
Calculate the percentage of iron according to formula (2):
Fe(%) = V- (V/- V2)1× 0. 055 85 × 100mc
Wherein: c—actual concentration of potassium dichromate standard titration solution, mol/L; V—volume of potassium dichromate standard titration solution consumed when titrating the sample solution, mL*(2)
GB/T5121.9—1996
V.—volume of potassium dichromate standard titration solution consumed when titrating the blank solution for the first time, ml. V2—volume of potassium dichromate standard titration solution consumed when titrating the blank solution for the second time, ml; mo
mass of the sample, g+
0.05585—mass of iron equivalent to 1.00ml potassium dichromate standard titration solution [c1/6K,Cr2O,）=1.000mol/L] g/mol.
The result is expressed to two decimal places.
15 Allowable difference
The difference between the analysis results of laboratories should not be greater than the allowable difference listed in Table 4. Table 4
>0.501.50
>1.50~4.00
>4. 00~7. 006 Wash the precipitate with water and put it into the original beaker. Dissolve the residual precipitate on the filter paper in the original beaker with 20mL hot hydrochloric acid with a few drops of hydrogen peroxide. Wash the filter paper with hot water 4 times, add the washing liquid into the main solution, cover with a table dish, heat and boil to destroy the hydrogen peroxide and boil until the solution is transparent, and cool. Wash the table blood and the wall of the cup with water, and remove Table III. 13.3.7 Dilute the volume to about 130mL with water, add 1mL sodium tungstate solution, add titanium trichloride solution dropwise until a stable blue color appears, and slowly titrate with potassium dichromate standard titration solution until the blue disappears, and do not record the milliliters. 13.3.8 Immediately add 10mL of mixed acid and three drops of sodium diphenylamine sulfonate solution, and titrate with potassium dichromate standard titration solution until a stable purple color appears as the end point.
14 Expression of analysis results
Calculate the percentage of iron according to formula (2):
Fe(%) = V- (V/- V2)1× 0. 055 85 × 100mc
Wherein: c—actual concentration of potassium dichromate standard titration solution, mol/L; V—volume of potassium dichromate standard titration solution consumed when titrating the sample solution, mL*(2)
GB/T5121.9—1996
V.—volume of potassium dichromate standard titration solution consumed when titrating the blank solution for the first time, ml. V2—volume of potassium dichromate standard titration solution consumed when titrating the blank solution for the second time, ml; mo
mass of the sample, g+
0.05585—mass of iron equivalent to 1.00ml potassium dichromate standard titration solution [c1/6K,Cr2O,）=1.000mol/L] g/mol.
The result is expressed to two decimal places.
15 Allowable difference
The difference between the analysis results of laboratories should not be greater than the allowable difference listed in Table 4. Table 4
>0.501.50
>1.50~4.00
>4. 00~7. 006 Wash the precipitate with water and put it into the original beaker. Dissolve the residual precipitate on the filter paper in the original beaker with 20mL hot hydrochloric acid with a few drops of hydrogen peroxide. Wash the filter paper with hot water 4 times, add the washing liquid into the main solution, cover with a table dish, heat and boil to destroy the hydrogen peroxide and boil until the solution is transparent, and cool. Wash the table blood and the wall of the cup with water, and remove Table III. 13.3.7 Dilute the volume to about 130mL with water, add 1mL sodium tungstate solution, add titanium trichloride solution dropwise until a stable blue color appears, and slowly titrate with potassium dichromate standard titration solution until the blue disappears, and do not record the milliliters. 13.3.8 Immediately add 10mL of mixed acid and three drops of sodium diphenylamine sulfonate solution, and titrate with potassium dichromate standard titration solution until a stable purple color appears as the end point.
14 Expression of analysis results
Calculate the percentage of iron according to formula (2):
Fe(%) = V- (V/- V2)1× 0. 055 85 × 100mc
Wherein: c—actual concentration of potassium dichromate standard titration solution, mol/L; V—volume of potassium dichromate standard titration solution consumed when titrating the sample solution, mL*(2)
GB/T5121.9—1996
V.—volume of potassium dichromate standard titration solution consumed when titrating the blank solution for the first time, ml. V2—volume of potassium dichromate standard titration solution consumed when titrating the blank solution for the second time, ml; mo
mass of the sample, g+
0.05585—mass of iron equivalent to 1.00ml potassium dichromate standard titration solution [c1/6K,Cr2O,）=1.000mol/L] g/mol.
The result is expressed to two decimal places.
15 Allowable difference
The difference between the analysis results of laboratories should not be greater than the allowable difference listed in Table 4. Table 4
>0.501.50
>1.50~4.00
>4. 00~7. 00
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