GB/T 5686.1-1988 Chemical analysis methods for manganese-silicon alloys - Potentiometric titration method for determination of manganese content

GB/T 5686.1-1988 Chemical analysis method for manganese-silicon alloys - Potentiometric titration for determination of manganese content GB/T5686.1-1988 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Chemical analysis method of silicomanganese alloy
The potentiometric titration method forthe determination of manganese contentUDC 669.74'782
GB 5686.1—88
Replaces GB5686.1—85
This standard is equivalent to the international standard 1SO4159—1978 "Ferromanganese and ferrosilicomanganese—Determination of manganese content—Potentiometric titration method". Subject content and scope of application
This standard specifies the determination of manganese content by potentiometric titration. This standard is applicable to the determination of manganese content in silicomanganese alloy. Determination range: 55.00%~80.00%. 2 Method Summary
The sample is decomposed with hydrochloric acid, hydrofluoric acid and perchloric acid. In a pyrophosphate medium, the pH is controlled and the manganese content is determined by potassium permanganate potentiometric titration. The reaction formula is as follows:
4Mn?++Mn0+8H++15(H2P20z)2-5Mn(H2P20,)+4H203 Reagents
3.1 Perchloric acid (p1.67g/mL).
3.2 Hydrofluoric acid (p1.15g/mL).
3.3 Hydrochloric acid (p1.19g/mL).
3.4 ​​Hydrochloric acid (1+2).
3.5 Hydrochloric acid (1+4).
3.6 Saturated sodium pyrophosphate solution: Weigh 145g sodium pyrophosphate (NaP207·10H20) and dissolve it in 1L hot water. Heat to a local temperature not exceeding 60℃ until the reagent is completely dissolved, cool and mix. 3.7 Potassium permanganate: Recrystallize and prepare when needed. 3.7.1 Place 50g potassium permanganate in a conical flask (4.1) and dissolve it in 200mL hot water (70~80C). Install a reflux condenser (4.2) on the flask, boil the solution for 20min, and quickly filter the hot solution under vacuum using a porous glass crucible (4.3). Cool the filtrate in ice water and stir vigorously. Let it stand for 10min to allow the fine crystalline precipitate to settle. Gently pour off the clear liquid above, scrape the crystals into a porous glass crucible with a glass spatula, and draw the filtrate for several minutes to remove most of the mother liquor. 3.7.2 Dissolve the crystals (3.7.1) in 160 mL of distilled water and recrystallize. After filtering and suction for about 5 minutes, scrape the crystals with a glass spatula onto a 150 mm diameter table, protect from light and dust, and dry in the air. Grind with a glass spatula, and when the crystals no longer clump, dry at 110 ° C for 2 hours. Then put them into a weighing bottle with a ground glass stopper and store them in a dark place. This salt contains 34.76% (m/m) manganese.
3.8 Potassium permanganate standard solution: c(KMnO.) = 0.01 mol/L. 3.8.1 Preparation
Weigh 1.60g potassium permanganate and dissolve it in 1000mL water. Leave it for 6 days, filter it with glass wool or porous glass crucible and transfer it into brown glass. Approved by the Ministry of Metallurgical Industry of the People's Republic of China on September 8, 1988 274
Implemented on January 1, 1990
National Standard of the People's Republic of China
Chemical Analysis Methods of Silicomanganese Alloy
Gravimetric Determination of Silicon Content
Methods for Chemical Analysis of Silicomanganese Alloy The gravimetric method for the determination of silicon content This standard is applicable to the determination of silicon content in silicomanganese alloy. Determination range: 8.00～30.00%. UDC 669.74' 782
：543.21
GB 5686.2-85
This standard complies with GB146778 "General Principles and General Provisions for Chemical Analysis Methods of Metallurgical Products". This standard equivalently adopts [International Standard ISO4158-1978 "Ferrosilicon, Ferrosilicomanganese and Ferrosilicochrome-Determination of Silicon Content-Gravimetric Method". Method Summary
The sample is oxidized and melted with sodium peroxide to convert silicon into silicate, which is leached with acid. The silicate is dehydrated twice by evaporation in a perchloric acid medium, and the impure silicon dioxide is weighed. The silicon dioxide is volatilized twice with hydrofluoric acid-sulfuric acid, and the residue is weighed, and the pure silicon dioxide is determined by subtraction. Reagents
Sodium peroxide.
Sodium carbonate (anhydrous).
Ammonium hydroxide (p0.90g/ml)a
Perfluoric acid (p1.61g/ml)*.
Hydrofluoric acid (p1.14g/ml).
Hydrochloric acid (p1.19g/m1)
Hydrochloric acid (1+9).
Sulfuric acid (p1.84g/m1)
Sulfuric acid (1+1).
Silver nitrate solution (1%).
3 Apparatus
Crock, volume 40ml, silicon-free iron, nickel or zirconium crucible. Beaker, for dissolving melt, made of polytetraethylene, stainless steel or high-purity nickel. 3.3 Platinum III, volume 40ml.
Glass funnel with ribs, diameter 75mm. 3.4
The sample should pass through a 0.125mm sieve.
Analysis steps
*When heating perchloric acid gastric smoke, take care to prevent danger. Issued by the National Bureau of Standards on December 4, 1985
Implemented on October 1, 1986
5.1 Sample quantity
Weigh 1.0000g of sample. bzxZ.net
5.2 Blank test
Perform a blank test with the sample.
5.3 Determination
GB 5686.2-85
5.3.1 Place the sample (5.1) in a crucible (3.1) containing 10 to 12g of sodium peroxide (2.1), mix carefully, and cover with 3g of sodium peroxide (2.1) or 3g of sodium carbonate (2.2) to prevent sample loss. Place the sample and flux on a 350-400℃ electric heating plate and heat until the melt turns black. Hold the crucible with crucible tongs and rotate it over the flame. To avoid explosion, heat it slowly first, then heat it strongly until it is completely melted, and keep the molten product in a red-hot state for 5 minutes. Let it cool. 5.3.2 Place the crucible in a beaker (3.2) filled with 200ml of water, cover it with a watch glass, and when there are no bubbles, take out the crucible and wash it with hot water. Collect the washing liquid in the same beaker, transfer the alkaline solution to a 600ml beaker filled with 30ml of hydrochloric acid (2.6), stir the solution, and add 100ml of perchloric acid (2.4) after the salts are dissolved. 5.3.3 Place the beaker on a high-temperature electric hot plate until white perchloric acid smoke is emitted. Continue heating until the smoke-emitting residue begins to crystallize and becomes viscous. Remove and cool. Slowly add 20 ml hydrochloric acid (2.6) and a few milliliters of hot water along the inner wall of the beaker to soak. Stir and dilute with 250 ml boiling water. Stir and let stand.
5.3.4 Filter the silica onto 12.5 cm ordinary quantitative filter paper in a grooved glass funnel (3.4). Keep the filtrate, wipe the beaker with a wipe and warm water, wash the filter paper with warm hydrochloric acid (2.7) until there is no yellow color of iron salt, and finally wash it with hot water several times until there is no chloride ion [check with silver nitrate solution (2.10) for a drop test]. The filter paper must be thoroughly washed to remove traces of perchloric acid that can cause combustion when burned.
Transfer the filtrate and washing liquid to the beaker used for the initial dehydration. Evaporate until the volume of the solution is about 250 ml. Add 20 ml of perfluoric acid (2.4), and then perform the first dehydration and leaching according to 5.3.3. Filter and wash the precipitate with new filter paper according to 5.3.4, but use cold water instead of hot water for the final wash.
5.3.5 Place the two filter papers containing the silica precipitate in a platinum dish (3.3). Add 4 drops of ammonium hydroxide (2.3) on the filter paper*, initially dry and burn in a high-temperature furnace ± not exceeding 400°C. Let cool. Add 1 ml of sulfuric acid (2.9) and evaporate until no sulfuric acid smoke is released, then burn at 1100°C to constant weight, cool in a desiccator, and weigh the platinum III containing impure silica. 5.3.6 Moisten the impure silica with a few drops of water. Add about 10 ml of hydrofluoric acid (2.5) and 2 to 3 drops of sulfuric acid (2.8) Evaporate to -10, and no sulfuric acid smoke is released. Perform the second volatilization under the same conditions, but use 2ml hydrofluoric acid. Burn in a high-temperature furnace at 1100℃ to constant weight, cool in a desiccator, and weigh the platinum III containing impurities. 6 Calculation of analysis results
Calculate the percentage of silicon by the following formula:
5i (%) =-((m=m2) = (ma=m))×0.4674 × 100mo
Wherein: m, — the mass of impure silicon dioxide and platinum III measured in 5.3.5, g; m2--- the mass of impurities and platinum III measured in 5.3.6, g; m3-- the mass of impure silicon dioxide and platinum dish measured in the air test, g; m-- the mass of impurities and platinum blood measured in the air test, g; mo-- the sample volume, g;
0.4674-- the conversion factor of silicon dioxide to silicon. 7 Tolerance
The difference in analysis results between laboratories should not be greater than the allowable difference listed in the following table. * To reduce the risk of less silicon dioxide coming out of the platinum dish when perchlorate volatilizes. 278
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