Some standard content:
Chemical Industry Standard of the People's Republic of China
Industrial Iron Oxide
1 Subject Content and Scope of Application
HG/T 2574—
This standard specifies the technical requirements, test methods, inspection rules, as well as marking, packaging, transportation and storage of industrial iron oxide. This standard applies to iron oxide obtained by thermal decomposition of ferrous salts or other methods. This product is mainly used as raw materials for soft ferrites, hard ferrites, polishing pastes and other industries. Molecular formula: Fe203
Relative molecular mass: 159.69 (according to the international relative atomic mass in 1989) 2 Reference standards
Preparation of standard solution for titration analysis (volume analysis) of chemical reagents GB/T 601
Preparation of standard solution for determination of impurities of chemical reagents GB/T 602
GB/T603 Preparation of preparations and products used in test methods of chemical reagents GB1250 Expression and determination method of limit values GB/T5211.15 Determination of oil absorption of pigments
Manual operation by water method
GB/T5211.18 Determination of sieve residue of pigments
General rules for sampling of chemical products
GB/T 6678
GB/T 6682
Specifications and test methods for analytical laboratory water GB8946
Plastic woven bags
3Product classification
Industrial iron oxide is divided into two types:
Type 1 is mainly used for soft and hard ferrites;
Type I is used for polishing paste and other industries.
4Technical requirements
4.1Appearance: brown or brown red powder. 4.2 Industrial iron oxide shall meet the requirements of the following table: Approved by the Ministry of Chemical Industry of the People's Republic of China on February 9, 1994 and implemented on July 1, 1994
Main content (in terms of Fe2())
Ferrous oxide (Fe2O3) content
Loss on drying
Silicon dioxide (SiO2) content
Aluminum (AI) content
Manganese (Mn) content
Calcium (Ca) content
Magnesium (Mg) content
Potassium (K) content
Sodium (Na) content
Sulfate (as SO) content
Chloride (as CI) content
45um test sieve residue
Ignition loss
Oil absorption·g/100g
Test method
HG/T2574-94
Superior product
Qualified product
%(m/m)bZxz.net
The reagents and water used in this standard, unless otherwise specified, refer to analytical pure reagents and grade 3 water specified in GB/T6682. The standard titration solution, impurity standard solution, preparation and product required in the test, unless otherwise specified, shall be prepared in accordance with the provisions of GB/T601, GB/T602 and GB/T603. 5.1 Determination of main content
5.1.1 Potassium dichromate method
5.1.1.1 Summary of method
Dissolve the sample with hydrochloric acid solution, add stannous chloride to reduce ferric iron to ferrous iron, then add mercuric chloride solution to remove excess stannous chloride, and titrate with potassium dichromate standard titration solution using sodium diphenylamine sulfonate as indicator. 5.1.1.2 Reagents and materials
5.1.1.2.1 Hydrochloric acid (GB/T622) solution: 1+1; 5.1.1.2.2 Stannous fluoride (GB/T638) solution: 100g/L; Weigh 10g of stannous chloride and dissolve it in 10mL of hydrochloric acid (GB/T622), and dilute it to 100ml with water; 5.1.1.2.3 Saturated solution of mercuric chloride (HG/T3-1068): 60~100g/L; 5.1.1.2.4 Sulfur-phosphorus mixed acid: Add 30mL of sulfuric acid (GB/T625) to 140mL of water under cooling, and then add 30mL of phosphoric acid 212
(GB/T 1282);
HG/T 2574--94
5.1.1.2.5 Potassium dichromate (GB/T642) standard titration solution: c (1/6K.Cr2O,) about 0.1mol/L; 5.1.1.2.6 Sodium diphenylamine sulfonate indicator solution: 5g/L. 5.1.1.3 Analysis steps
Weigh about 0.3g of sample (accurate to 0.0002g), place in a 250mL conical flask, add 30mL of hydrochloric acid solution, heat to completely dissolve the sample, continue to heat to a slight boil, slowly add stannous chloride solution while stirring until the solution just turns colorless, then add 12 drops in excess, cool the conical flask in running water to room temperature, quickly add 10mL of mercuric chloride solution, shake until a white, silky precipitate appears, and let stand for about 1min. Add 30ml sulfur-phosphorus mixed acid, 50ml water and 3 drops of sodium diphenylamine sulfonate indicator solution, and titrate with potassium dichromate standard titration solution. The end point is when the solution changes from green to blue-green and then to purple. Mercury-containing waste liquid shall not be discharged directly into the sewer, but shall be properly treated. For treatment methods, see Appendix A. 5.1.1.4 Expression of analysis results
The main content (in Fe2O3) ri expressed as mass percentage is calculated according to formula (1): c: V×0. 079 85 ×100
Wherein: c—--actual concentration of potassium dichromate standard titration solution, mol/L; V
volume of potassium dichromate standard titration solution consumed in titration, mL; m
mass of sample, g;
(1)
0.07985—mass of iron oxide in grams equivalent to 1.00mL potassium dichromate standard titration solution [c(1/6KCr.0,)=1.000mol/LJ.
5.1.1.5 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result. The absolute difference of the parallel determination results shall not exceed 0.2%. 5.1.2 Titanium trichloride method
5.1.2.1 Method summary
Dissolve the sample in hydrochloric acid, add stannous chloride and titanium trichloride to reduce the ferric iron to ferrous iron, use sodium diphenylamine sulfonate as an indicator, and titrate with potassium dichromate standard titration solution to a purple-red endpoint. 5.1.2.2 Reagents and materials
5.1.2.2.1 Hydrochloric acid (GB/T622) solution: 1+1; 5.1.2.2.2 Stannous chloride (GB/T638) solution: 100g/L; Weigh 10g of stannous chloride and dissolve it in 10mL of hydrochloric acid (GB/T622), and dilute it to 100mL with water; 5.1.2.2.3 Potassium permanganate (GB/T643) solution: 50g/L; 5.1.2.2.4 Titanium trichloride solution: Measure 10mL of 15% titanium trichloride solution and dilute it to 100mL with hydrochloric acid solution (5.1.2.2.1); 5.1.2.2.5 Sulfur-phosphorus mixed acid: Add 30mL of sulfuric acid (GB/T625) to 140ml of water under cooling, and then add 30ml of phosphoric acid (GB/T 1282);
5.1.2.2.6 Potassium dichromate (GB/T642) solution: 5g/L; 5.1.2.2.7 Potassium dichromate (GB/T642) standard titration solution: c(1/6KzCrzO,) about 0.1mol/L; 5.1.2.2.8 Indigo carmine indicator solution: 5g/L;
5.1.2.2.9 Sodium diphenylamine sulfonate indicator solution: 5g/L. 5.1.2.3 Analysis steps
Weigh about 0.3g of sample (accurate to 0.0002g), place it in a 500mL conical flask, add 30mL of hydrochloric acid solution, heat to completely dissolve the sample, continue to heat to near boiling, slowly add stannous chloride solution while stirring until the solution just turns colorless, then add a few drops in excess, and cool the conical flask to room temperature in running water. Add potassium permanganate dropwise while shaking until the solution turns brown, add water to about 100 ml, heat until the solution turns transparent, remove, and add stannous chloride dropwise while shaking until it turns light yellow. Add 4-5 drops of indigo red indicator solution, add titanium trichloride dropwise until the blue color of the solution just disappears, then add potassium dichromate solution (5.1.2.2.6) until it turns bright blue, dilute with water to about 300 ml, and cool. Add 30 ml of sulfur-phosphorus mixed acid and 3 drops of sodium diphenylamine sulfonate indicator solution, and titrate with potassium dichromate standard titration solution (5.1.2.2.7) until the solution turns purple, which is the end point. 5.1.2.4 Expression of analysis results
Main content expressed as mass percentage (in terms of FeO:) r2 is calculated according to formula (2): c : V × 0. 079 85 × 100
Wherein: —actual concentration of potassium dichromate standard titration solution, mol/L; V——volume of potassium dichromate standard titration solution consumed in titration, ml; (2)
Mass of sample, g;
0.07985——The mass of iron oxide in grams equivalent to 1.00ml potassium dichromate standard titration solution c (1/6K,Cr,O,) = 1.000mol/L).
5.1.2.5 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result. The absolute difference of the parallel determination results shall not exceed 0.2%. 5.2 Determination of ferrous oxide content
5.2.1 Method summary
Under the protection of inert gas, dissolve the sample with hydrochloric acid solution, use sodium diphenylamine sulfonate as the indicator, and titrate with potassium dichromate standard titration solution.
5.2.2 Reagents and materials
5.2.2.1 Hydrochloric acid (GB/T622) solution: 1+1: 5.2.2.2 Sulfur-phosphorus mixed acid: see 5.1.1.2.4; 5.2.2.3 Potassium dichromate (GB/T642) standard titration solution: c (1/6K2Crz,) about 0.01mol/L; pipette 10ml. Potassium dichromate standard titration solution (5.1.1.2.5), place it in a 100mL volumetric flask, dilute to the scale with water, and shake well. 5.2.2.4 Sodium diphenylamine sulfonate indicator solution: see 5.1.1.2.6. 5.2.2.5 Nitrogen
5.2.3 Analysis steps
Weigh about 1.0g of sample (accurate to 0.0002g), place in a 250mL conical flask, pass nitrogen for about 10 minutes to drive out the air in the flask, slowly add 30mL of hydrochloric acid solution, continue to pass nitrogen, heat to completely dissolve the sample, and quickly cool to room temperature. Stop passing nitrogen, add 30ml. sulfur-phosphorus mixed acid, 50ml water and 3 drops of sodium diphenylamine sulfonate indicator solution, and titrate with potassium dichromate standard titration solution until the solution turns purple as the end point.
Conduct a blank test at the same time.
5.2.4 Expression of analytical results
The content of ferrous oxide (FeO) expressed as mass percentage is calculated according to formula (3): x3
. (vV)×0. 071 85 ×100
7. 185c(V--V.)
Wherein 1: —-actual concentration of potassium dichromate standard titration solution, mol/L; V--volume of potassium dichromate standard titration solution consumed in titration, mL; V--volume of potassium dichromate standard titration solution consumed in blank test, mL; (3)
m--mass of sample, g;
0.07185---mass of ferrous oxide in grams equivalent to 1.00mL potassium dichromate standard titration solution Lc (1/6K2Cr0,) = 1.000mol/L.].
5.2.5 Allowable difference
HG/T 2574--94
Take the arithmetic mean of the parallel determination results as the determination result. The absolute difference of the parallel determination results shall not exceed 0.05%. 5.3 Determination of loss on drying
5.3.7 Instruments and equipment
Weighing bottle: Φ50mm×30mm.
5.3.2 Analysis steps
Weigh about 3g of sample (accurate to 0.0002g) and place it in a weighing bottle that has been dried to constant weight at 105~~110℃. Move it into an electric constant temperature drying oven, open the bottle cap, dry it at 105~110℃ for 2h, cool it in a dryer, and weigh it (accurate to 0.0002g). 5.3.3 Expression of analysis results
The drying loss expressed as mass white fraction r is calculated according to formula (4): mr-m2×100
Wherein: m, — the mass of the weighing bottle and the sample before drying, gm2——the mass of the weighing bottle and the sample after drying, g; m——the mass of the sample, g.
(4)
5.3.4 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result. The absolute difference of the parallel determination results is not more than 0.05% for type 1 and not more than 0.10% for type I.
5.4 Determination of silicon dioxide content
5.4.1 Summary of method
Dissolve the sample with hydrochloric acid and nitric acid, dehydrate with perchloric acid, and filter. Add hydrofluoric acid to volatilize silicon dioxide, and calculate the silicon dioxide content based on the loss. 5.4.2 Reagents and materials
5.4.2.1 Hydrochloric acid (GB/T 622);
5.4.2.2 Hydrochloric acid (GB/T622) solution: 1+1; 5.4.2.3
Hydrochloric acid (GB/T622) solution: 1+10;
Perfluoric acid (GB/T623);
5.4.2.5 Sulfuric acid (GB/T625) solution: 1+1; 5.4.2.6 Nitric acid (GB/T 626);
Hydrofluoric acid (GB/T.620);
5.4.2.8 Silver nitrate (GB/T670) solution: 17g/L. 5.4.3 Instruments and equipment
Platinum crucible: capacity is 30mL.
5.4.4 Analysis steps
Weigh 10.0g of sample (accurate to 0.1g) and place it in a 300ml beaker. Add 30ml of water and 30ml of hydrochloric acid (5.4.2.1), cover with surface IIIi, heat on a hot plate to dissolve, and continue heating to concentrate until the volume of the solution is about 30ml. Add 5mL of nitric acid and 60mL of perchloric acid solution, and heat strongly until perchlorate precipitates. Remove the beaker, cool it, add 20mL of hydrochloric acid solution (5.4.2.2), add warm water to a total volume of about 200mL, filter with slow quantitative filter paper, scrape the residue attached to the inner wall of the beaker onto the filter paper with a glass rod with a rubber head, wash the filter paper with warm hydrochloric acid solution (5.4.2.3) until the filter paper is colorless, and then wash it with warm water 7 to 10 times. Transfer the precipitate and filter paper into platinum, dry and ash, and burn to constant weight at above 1100℃. Wet the residue with 2~3 drops of sulfuric acid solution, add about 2mL of hydrofluoric acid, heat on a hot plate until the white smoke of sulfuric acid is gone, and then burn to constant weight at above 1100℃. Perform a blank test at the same time. 5.4.5 Expression of analysis results
Silicon dioxide (SiO2) content expressed as mass percentage: Calculated according to formula (5): ml-mz-m3×100 -
(5)
Mass of platinum crucible and residue, g,
HG/T 2574-94
Mass of platinum crucible and residue after hydrofluoric acid treatment, g; m2
Mass of silicon dioxide in blank test, g;
m——Mass of sample, g.
5.4.6 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result. The absolute difference of the parallel determination results shall not exceed 0.003%. 5.5 Determination of aluminum content
5.5.1 Method summary
Dissolve the sample with hydrochloric acid and nitric acid, extract and separate the iron with methyl isobutyl ketone, and neutralize. Determine with aluminum reagent spectrophotometry. 5.5.2 Reagents and materials
5.5.2.1 Hydrochloric acid (GB/T622);
5.5.2.2 Hydrochloric acid (GB/T622) solution: 5+3; 5.5.2.3 Hydrochloric acid (GB/T622) solution: 10+13; 5.5.2.4
Nitric acid (GB/T626);
Sulfuric acid (GB/T625) solution: 1+1;
Ammonia (GB/T631) solution: 1+1;
Methyl isobutyl ketone (HG/T 3—1118); acetic acid-ammonium acetate buffer solution (pH 4-5); thioglycolic acid solution: 1+10;
5.5.2.10 Rose red ammonium tricarboxylate solution: 0.5g/L; 5.5.2.11 Aluminum standard solution: 1ml solution contains 0.01mgA1, prepared before use. Take 10mlL aluminum standard solution prepared according to GB/T602, place it in a 100mL volumetric flask, add water to dilute to the scale, and shake well. 5.5.2.12 p-Nitrophenol indicator solution: 1g/L. 5.5.3 Instruments and equipment
Spectrophotometer: with an absorption cell with a thickness of 1cm. 5.5.4 Analysis steps
5.5.4.1 Drawing of working curve
Use a pipette to transfer 0.00, 2.00, 5.00, 10.00, 15.00, 20.00 and 30.00 mL of aluminum standard solution respectively, place them in a set of 250 mL beakers, and add water to about 50 mL. Add 2 drops of p-nitrophenol indicator solution, and add ammonia water while shaking thoroughly until the solution turns yellow. Immediately add 1 ml of hydrochloric acid solution (5.5.2.3), shake well, transfer to a 100 mL volumetric flask, and dilute to the mark with water. Take 25 mL from it and place it in a 50 mL volumetric flask, add 5 mL of acetic acid-ammonium acetate buffer solution and 1.5mL of thioglycolic acid solution, shake well. Then add 3mL of rose red ammonium tricarboxylate solution, add water to the scale, shake well, and let it stand for 15min. Move it into a 1cm absorption cell, use the reagent blank solution as a reference, and measure its absorbance at a wavelength of 530nm. Use the aluminum content as the horizontal axis and the corresponding absorbance as the vertical axis to draw a working curve. 5.5.4.2 Determination
Weigh 1.00g of sample (0.40g for qualified products), accurate to 0.01g, place it in a 100mL beaker, add 15mL of hydrochloric acid (5.5.2.1) and 5mL of nitric acid, cover surface III, and heat on a hot plate to dissolve. Continue heating and concentrating to a solution volume of about 5mL. Cool, transfer to a 200mL separatory funnel (hereinafter referred to as separatory funnel A), wash the test solution attached to the inner wall of the beaker with 30mL hydrochloric acid solution (5.5.2.2) and put it into separatory funnel A, add 30ml methyl isobutyl ketone, shake vigorously for about 1min, let it stand, and put the water layer into another separatory funnel (hereinafter referred to as separatory funnel B). Add 2~~3mL hydrochloric acid solution (5.5.2.2) to separatory funnel A, shake vigorously for about 30s, let it stand, and put the water layer into separatory funnel B. Add 20mL methyl isobutyl ketone to separatory funnel B, shake vigorously for about 1min, let it stand, and put the water layer into a 200mL beaker. Add 2-3 mL of hydrochloric acid solution (5.5.2.2) to the methyl isobutyl ketone layer, shake vigorously for about 30 seconds, let it stand, put the water layer into a beaker, add 4 ml of sulfuric acid solution into the beaker, heat to remove the residual methyl isobutyl ketone, continue heating to produce white smoke for about 10 minutes. After cooling, add 20 ml of 216
HG/T 2574—94
water to dissolve. The following operations are as described in 5.5.4.1, starting from "add 2 drops of p-nitrophenol indicator solution..." and ending with "measure its absorbance". 5.5.5 Expression of analysis results
The aluminum (AI) content expressed as mass percentage is calculated according to formula (6): x
25×1000
Wherein: m---the mass of aluminum found from the working curve based on the absorbance of the sample solution, mg; m--the mass of the sample, g.
5.5.6 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result. The absolute difference of the parallel determination results shall not exceed 0.002%. 5.6 Determination of manganese content
5.6.1 Summary of method
Dissolve the sample in hydrochloric acid and measure by the standard addition method of atomic absorption spectrophotometry. Absorbance, draw a curve, and calculate the manganese content. 5.6.2 Reagents and materials
5.6.2.1 Hydrochloric acid (GB/T622) solution: 2+1; 5.6.2.2 Manganese standard solution: 1mL solution contains 0.1mgMn. 5.6.3 Instruments and equipment
Atomic absorption spectrophotometer: with a manganese hollow cathode lamp. 5.6.4 Analysis steps
(6)
5.6.4.1 Preparation of test solution
Weigh 10.0g sample (accurate to 0.1g), place in a 500mL beaker, add 200mL hydrochloric acid solution, cover with surface blood, and slowly heat to dissolve. Cool, rinse the watch glass and the inner wall of the beaker with a small amount of water, transfer to a 1000mL volumetric flask, add water to dilute to the scale, and shake well. This is test solution A. Use For the determination of manganese, magnesium, potassium and sodium content. 5.6.4.2 Determination
Use a pipette to transfer 5mL of test solution A in four portions and place them in 100mL volumetric flasks respectively. One portion does not contain manganese standard solution, and the other three portions are added with proportional manganese standard solution and diluted to the scale with water. Use the reagent blank to adjust the instrument absorbance to zero, spray the above solution in an air-acetylene flame, and measure the absorbance at a wavelength of 279.5nm. Draw a curve with the known amount of manganese concentration (ug/mL) in the test solution after adding manganese standard solution as the horizontal axis and the corresponding absorbance as the vertical axis. Extend the curve in the opposite direction to intersect with the horizontal axis. The distance from the intersection to the origin is the manganese concentration in the transferred test solution. 5.6.5 Expression of analysis results
The manganese (Mn) content α expressed as mass percentage is calculated according to the formula (7 )Calculation: c×100
mX10°X
Where: c-—the manganese concentration in the test solution obtained from the curve, uμg/mL; m
—the mass of the sample, 8.
5.6.6 Allowable difference
Take the arithmetic mean of the parallel determination results as the determination result. The absolute difference of the parallel determination results shall not exceed 0.02%. 5.7 Determination of calcium content
(7)
5.7.1 Summary of method
Dissolve the sample in hydrochloric acid, add strontium chloride solution, measure the absorbance by the standard addition method of atomic absorption spectrophotometry, draw a curve, and obtain the calcium content 217
5.7.2 Reagents and materials
5.7.2.1 Hydrochloric acid (GB/T622) solution: 2+1; HG/T 2574—94
5.7.2.2 Strontium chloride (HG/T3-1073) solution: 30g/L; 5.7.2.3 Calcium standard solution: 1ml solution contains 0.1mgCa. 5.7.3 Instruments and equipment
Atomic absorption spectrophotometer: with calcium hollow cathode lamp. 5.7.4 Analysis steps
Weigh 5.00g sample (accurate to 0.01g), put it in a 250ml beaker, add 100mL hydrochloric acid solution, cover with a watch glass, slowly heat to dissolve, cool and transfer to a 250ml volumetric flask, and dilute to scale with water. Transfer 50ml of the above test solution to each of the 4 100mL volumetric flasks, and then use a pipette to add 5mL of strontium chloride solution to each, one part without adding calcium standard solution, and the other three parts respectively add proportional calcium standard solution and dilute to scale with water. Adjust the instrument absorbance to zero with reagent blank, spray the above solution in air-acetylene flame, measure absorbance at wavelength 422.7nm, draw a curve with known calcium concentration (μg/ml.) in the test solution after adding calcium standard solution as horizontal axis and corresponding absorbance as vertical axis, extend the curve in reverse direction to intersect with the horizontal axis, the distance from the intersection to the origin is the concentration of calcium in the transferred test solution.
5.7.5 Expression of analysis results
Calcium (Ca) content rg expressed as mass percentage is calculated according to formula (8): r8=
c×100
m×10°×
（8）
Where: C--calcium concentration in the test solution obtained from the curve, μg/mL; m -
mass of the sample, g.
5.7.6 Allowable difference
The arithmetic mean of the parallel determination results shall be taken as the determination result. The absolute difference of the parallel determination results shall not exceed 0.005%. 5.8 Determination of magnesium content
5.8.1 Summary of method
Dissolve the sample in hydrochloric acid, measure the absorbance by the standard addition method of atomic absorption spectrophotometry, draw a curve, and obtain the magnesium content. 5.8.2 Reagents and materials
Magnesium standard solution: 1mL solution contains 0.1mgMg. 5.8.3 Instruments and equipment
Atomic absorption spectrophotometer: with a magnesium hollow cathode lamp. 5.8.4 Analysis steps
Use a pipette to take 20mL (superior product), 10mL (first-class product), or 5mL (qualified product) of test solution A (5.6.4.1) in four portions, and keep them in 100mL volumetric flasks respectively. One portion does not add magnesium standard solution, and the other three portions are added with proportional magnesium standard solution respectively, and diluted with water to the scale. Use reagent blank to adjust the instrument absorbance to zero, spray the above solution in air-acetylene flame, and measure the absorbance at a wavelength of 285.2nm. Draw a curve with the known amount of magnesium concentration (ug/mL) in the test solution after adding magnesium standard solution as the horizontal axis and the corresponding absorbance as the vertical axis. Extend the curve in the opposite direction to intersect with the horizontal axis. The distance from the intersection to the origin is the magnesium concentration in the test solution. 5.8.5 Expression of analysis results
Magnesium (Mg) content expressed as mass percentage. Calculate according to formula (9): rg
m×10°x
Wherein: c-
HG/T 2574-94
The concentration of magnesium in the test solution obtained from the curve, μg/mL; V-the volume of test solution A removed, mL; -the mass of the sample weighed in 5.6.4.1, g. m
5.8.6 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result. The absolute difference of the parallel determination results shall not exceed 0.002%. 5.9. Determination of potassium content
5.9.1 Summary of method
Dissolve the sample in hydrochloric acid, measure the absorbance by the standard addition method of atomic absorption spectrophotometry, draw a curve, and obtain the potassium content. 5.9.2 Reagents and materials
Potassium standard solution: 1mL of solution contains 0.1mgK. 5.9.3 Instruments and equipment
Atomic absorption spectrophotometer: with potassium hollow cathode lamp. 5.9.4 Analysis steps
Use a pipette to take four portions of 50mL test solution A (5.6.4.1) and place them in 100mL volumetric flasks respectively. Do not add potassium standard solution to one portion, and add proportional potassium standard solution to the remaining three portions respectively, and dilute to the scale with water. Use reagent blank to adjust the instrument absorbance to zero, spray the above solution in an air-acetylene flame, and measure the absorbance at a wavelength of 766.5nm. Draw a curve with the known amount of potassium concentration (μg/mL) in the test solution after adding potassium standard solution as the horizontal axis and the corresponding absorbance as the vertical axis. Extend the curve in the opposite direction to intersect with the horizontal axis. The distance from the intersection to the origin is the potassium concentration in the test solution. 5.9.5 Expression of analysis results
The potassium (K) content expressed as mass percentage is calculated according to formula (10): 10
m×10°×
Wherein: (-the potassium concentration in the test solution obtained from the curve, μg/mL; -the mass of the sample weighed in 5.6.4.1, g. 5.9.6 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result. The absolute difference of the parallel determination results shall not exceed 0.002%. : 5.10 Determination of sodium content
5.10.1 Summary of method
Dissolve the sample in hydrochloric acid, measure the absorbance by the standard addition method of atomic absorption spectrophotometry, draw a curve, and obtain the sodium content. 5.10.2 Reagents and materials
Sodium standard solution: 1mL of solution contains 0.1mgNa. 5. 10.3 Instruments and equipment
Atomic absorption spectrophotometer: with a sodium hollow cathode lamp. 5.10.4 Analysis steps
Use a pipette to transfer four portions of 20mL of test solution A (5.6.4.1) and place them in 100mL volumetric flasks respectively. Do not add sodium standard solution to one portion. Add proportional sodium standard solution to the remaining three portions and dilute to the scale with water. Use a reagent blank to adjust the instrument absorbance to zero, spray the above solution in an air-acetylene flame, measure the absorbance at a wavelength of 588.9nm, and draw a curve with the known amount of sodium concentration (ug/ml) in the test solution after adding the sodium standard solution as the horizontal axis and the corresponding absorbance as the vertical axis. Extend the curve in the opposite direction to intersect with the horizontal axis. The distance from the intersection to the origin is the concentration of sodium in the test solution. 5.10.5 Expression of analysis results
HG/T 2574-94
The sodium (Na) content xn expressed as mass fraction is calculated according to formula (11): Tn
Wherein:
m×10°×
The sodium concentration in the test solution obtained from the curve, μg/mL; The mass of the sample weighed in 5.6.41, g. 5.10.6 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result. The absolute difference between the parallel determination results shall not exceed 0.005%. 5.11 Determination of carbonate content
5.11.1 Summary of method
Use hydrochloric acid to dissolve the sample, add zinc to reduce Fe(III) to Fe(I), then add barium chloride to precipitate sulfate, weigh the barium sulfate to determine the sulfate content. 5.11.2 Reagents and materials
5.11.2.1 Zinc: granular;
5.11.2.2 Hydrochloric acid (GB/T 622);
5.11.2.3 Hydrochloric acid (GB/T622) solution: 1+10; 5.11.2.4 Barium chloride (GB/T652): solution: 100g/L; 5.11.2.5 Silver nitrate (GB/T670) solution: 17g/L. 5.11.3 Analysis steps
Weigh about 2 bags of sample (accurate to 0.01g), place in a 300mL beaker, add 30mL hydrochloric acid (5.11.2.2) and heat to dissolve, add water to the total volume of the solution is about 10Qml, add 5g zinc particles, heat in a boiling water bath to reduce Fe () to Fe (II). When the red color of the solution disappears, filter it immediately, wash with warm hydrochloric acid solution (5.11.2.3) until the filter paper is colorless, and then wash with warm water 4~~5 times. Combine the filtrate and washing liquid, add water to about 300 ml, heat to 60-70°C, add 10 mL of hot barium chloride solution dropwise, heat on a boiling water bath for 30 min, let stand overnight, filter with slow quantitative filter paper, and wash with water until there is no chloride ion reaction in the washing liquid (check with silver nitrate solution). Transfer the filter paper and the precipitate together into a crucible that has been calcined to constant weight at about 700°C. After drying and ashing, transfer it into a muffle furnace and calcine at about 700°C to constant weight. 5.11.4 Expression of analysis results
The sulfate (S) content expressed as mass percentage is calculated according to formula (12): (m-mz)×0.4116
41.16(m--m2)
Where: m2 is the mass of the crucible and residue after calcination.g; m---the mass of the crucible, g;
the mass basis of the sample.g;
0.4116---the coefficient for converting barium sulfate to sulfate. 5.11.5 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result. The absolute difference of the parallel determination results shall not exceed 0.02%. 5.12 Determination of chloride content
5.12.1 Summary of method
Add phosphoric acid to the sample, heat and dissolve, the nitrogen ions are distilled out as hydrogen chloride, and in the nitric acid medium, the chloride ions react with silver nitrate to form silver chloride, which is determined by visual turbidimetry.
5.12.2 Reagents and materials
5.12.2.1 Phosphoric acid (GB/T1282);
5.12.2.2 Nitric acid (GB/T626) solution: 1+1; 220
HG/T 2574--94
5.12.2.3 Silver nitrate (GB/T670) solution: 17g/L. 5.12.2.4 Chloride standard solution: 1mL solution contains 0.01mgCl, prepared before use. Use a pipette to transfer 10mL of the chloride standard solution prepared according to GB/T602, place it in a 100mL volumetric flask, add water to dilute to the mark, and shake well.
5.12.3 Instruments and equipment
5.12.3.1 Colorimetric tube: 25mL;
5.12.3.2 Distillation apparatus: The distillation apparatus is shown in Figure 1. Rubber tube (for connection)
Rubber stopper
Cooling water
Sample + phosphoric acid
Figure 1 Distillation apparatus
1--1000mL round-bottom flask; 2-300ml. conical flask; 3-condenser with cooling water; 4-300mlL collecting bottle 5.12.4 Analysis steps
Connect parts 2, 3, and 4 of the distillation apparatus according to the figure. Weigh 0.300g of the sample (accurate to 0.001g), place it in conical flask 2, add 20mL of phosphoric acid, heat it, and when the sample begins to dissolve, connect conical flask 2 and round-bottom flask 1 containing water that has been boiled in advance, and pass water vapor. Stop heating before white smoke emerges, and continue to pass water vapor until the hydrogen chloride completely enters the collecting flask 4. Transfer the distillate into a 100mL volumetric flask and dilute it to the mark with water.
Use a pipette to transfer 10mL of the test solution, place it in a colorimetric tube, add 1mL of nitric acid solution and 1mL of silver nitrate solution, dilute it to the mark with water, shake it well, and let it stand for 2min. The turbidity presented shall not be deeper than that of the standard turbidity solution. Preparation of standard turbidity solution: Take a certain volume of chloride standard solution according to the following regulations, and treat it in the same way as the sample starting from "add 1mL of nitric acid solution·".
Superior product: 3.0mL;
Qualified product: 4.5ml;
Qualified product: 6.0mL.
5.13 Determination of particle size
5.13.1 Method 1 Sedimentation method
This method is applicable to type 1 products.
5.13.1.1 Method summary
HG/T 2574-94
Disperse the sample in sodium pyrophosphate solution and determine the particle size by sedimentation method. 5.13.1.2 Reagents and materials
Sodium pyrophosphate (HG/T3-1288) solution: 2g/L. 5.13.1.3 Instrument
Automatic particle size determination device.
5.13.1.4 Analysis steps
Weigh 8.0g of sample (accurate to 0.1g), place it in a beaker, add 400mL of sodium pyrophosphate solution, operate according to the instrument manual, and use an automatic particle size analyzer to determine the product particle size. 5.13.2 Method 2 Sieving method
This method is applicable to Type II products!
Perform the determination according to the provisions of (GB/T5211.18. Weigh 10g of sample, the dispersant is sodium pyrophosphate, and the amount added is 4% of the sample amount. The treatment of the sieve residue shall be carried out according to the provisions of Article 4.3a. 5.14 Determination of loss on ignition
5.14.1 Analysis steps
Weigh about 2g of sample (accurate to 0.01g), placed in a porcelain ware that has been calcined to constant weight at 750~800℃, transferred to a muffle furnace, and calcined to constant weight at 750~800℃.
5.14.2 Expression of analysis results
The ignition loss α13 expressed as mass percentage is calculated according to formula (13): a13
Where: m, the mass of the crucible and residue after calcination, g; m2-——the mass of the crucible, g;
mThe mass of the sample, g.
5.15 Determination of oil absorption
2×100
The determination is carried out according to the provisions of GB/T5211.15. Weigh 10g of the sample. 6 Inspection rules
(13)
6.1 Industrial iron oxide shall be inspected by the quality supervision and inspection department of the manufacturer in accordance with the provisions of this standard. The manufacturer shall ensure that all products leaving the factory meet the requirements of this standard. Each batch of products leaving the factory shall be accompanied by a quality certificate. The contents shall include: manufacturer name, factory address, product name, model, grade, net weight, batch number or production date, certification that the product quality meets this standard and the number of this standard. 6.2 The user has the right to inspect and accept the industrial iron oxide received in accordance with the provisions of this standard. 6.3 Each batch of products shall not exceed 30t.
6.4 Determine the number of sampling units in accordance with the provisions of Article 6.6 of GB/T6678. When sampling, insert the sampler vertically from the center of the packaging bag to 3/4 of the depth of the material layer to collect samples. After mixing the collected samples, reduce them to about 500g by quartering method and pack them in two clean and dry wide-mouth bottles with stoppers and seal them. A label is affixed to the bottle, indicating: manufacturer name, product name, model, grade, batch number, sampling date and name of the sampler. One bottle is used for inspection, and the other bottle is kept for three months for future reference. 6.5 If one of the test results does not meet the requirements of this standard, re-sampling should be carried out from twice the amount of packaging for verification. Even if one of the test results does not meet the requirements of this standard, the entire batch of products cannot be accepted. 6.6 When the supply and demand parties have objections to the product quality, they shall be handled in accordance with the provisions of the "Product Quality Law of the People's Republic of China". 6.7 The rounded value comparison method specified in GB1250 shall be used to determine whether the test results meet the standards. . 7 Marking, packaging, transportation, storage
7.1 The industrial iron oxide packaging bag should have firm and clear markings, including: manufacturer name, factory address, product name, trademark, model, etc. 222
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