GOST 21639.12-87

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  ГОСТ 21639.12-87

GOST 21639.12−87 Fluxes for electroslag remelting. Methods of determining the protoxide of manganese

GOST 21639.12−87

Group B09

STATE STANDARD OF THE USSR

FLUXES FOR ELECTROSLAG REMELTING

Methods of determining the protoxide of manganese

Fluxes for electroslag remelting. Methods for determination of manganous oxide

AXTU 0809

Valid from 01.01.88
until 01.01.93*
______________________________
* Expiration removed according to Protocol
The interstate Council for standardization,
Metrology and certification (I & C N 2, 1993). -
Note the manufacturer’s database.

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of ferrous metallurgy of the USSR

PERFORMERS

I. V. Stetsenko, I. K. Maiboroda, P. M. Gerashchenko, V. V. Miroshnichenko, O. V. Taranets

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from 20.02.87 N 302

3. INTRODUCED FOR THE FIRST TIME

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

This standard sets the photometric and atomic absorption methods for the determination of manganese oxide in flux for electroslag remelting (when the mass fraction of oxide of manganese, from 0.1 to 2.0%).

1. GENERAL REQUIREMENTS

1.1. General requirements for methods of analysis GOST 21639.0−76*.
______________
* On the territory of the Russian Federation GOST 21639.0−93. — Note the manufacturer’s database.

2. PHOTOMETRIC METHOD

2.1. The essence of the method

The method is based on the oxidation of bivalent manganese to the sulfur-phosphate environment before pneumococcal hodnoceni potassium with subsequent measurement of optical density of colored solution with spectrophotometer at a wavelength of 525 nm or photoelectrocolorimeter in a range of wavelengths from 500 to 550 nm.

2.2. Apparatus, reagents and solutions

Photoelectrocolorimeter or spectrophotometer.

Sulfuric acid GOST 4204−77, diluted 1:1 and 5:1000.

Orthophosphoric acid according to GOST 6552−80.

Hydrogen peroxide according to GOST 10929−76, a solution of 300 g/DM.

Sodium atomistically according to GOST 4197−74, a solution of 0.03 g/cm.

Potassium cognately, a solution of 50 g/DM: 50g jednolitego potassium is added to 1 DMof hot sulphuric acid (5:1000) and boil until dissolved. The hot solution is filtered. Before use, the solution is heated to dissolve the residue and use in hot conditions.

Potassium permanganate according to GOST 20490−75.

Manganese metal according to GOST 6008−82*.
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* On the territory of the Russian Federation GOST 6008−90. — Note the manufacturer’s database.

Manganese (II) sulfate 5-water according to GOST 435−77.

Standard solutions of protoxide of manganese

Solution a: 2,2280 g potassium permanganate placed in a beaker with a capacity of 600 cmand dissolved in the 400−450 cmof water, poured 10 cmof sulphuric acid (1:1) and restore the pneumococcal manganese with hydrogen peroxide, priliva her dropwise until discoloration of the solution. The solution was boiled for 8−10 min, cooled, poured into a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix

or 4,388 g of manganese sulphate was dissolved with water, transferred into a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix;

or 0,7752 g of manganese metal is placed in a beaker with a capacity of 200 cm, add 25 cmwater and 10 cmof sulphuric acid (1:1). Beaker cover watch glass, heat to dissolve the metal and continue to heat for 2−3 min. After cooling, the solution is transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.

Mass concentration of nitrous oxide of manganese in solution And is equal to 0.001 g/cm.

Solution B: 10 cmstandard solution And placed in a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix.

Mass concentration of nitrous oxide of manganese in solution B is equal to 0,

0001 g/cm.

2.3. Analysis

2.3.1. Aliquot part of the basic solution was 50 cmfor the mass concentration of oxide manganese up to 0.5%, or 20 cmwhen the mass fraction of oxide of manganese in excess of 0.5% prepared according to the method GOST 21639.2−76 or according to claim 3.3.1, is placed in a conical flask with a capacity of 250 cm, flow 10 cmof sulphuric acid (1:1), heated to fumes of sulfuric acid, cool, add 50 cmof water 5 cmof phosphoric acid and heated to boiling, then pour 10 cmof a solution of potassium jednolitego and boiled for 5 min, the Cooled solution is poured into a measuring flask with a capacity of 100 cm, made up to the mark with water and mix.

After an hour, measure the optical density of the test solution on the spectrophotometer at a wavelength of 525 nm or photoelectrocolorimeter in a range of wavelengths from 500 to 550 nm in a cuvette with the thickness of the absorbing layer 30 mm. In a solution of comparison used aliquot part of the solution in which manganese acid destroyed one or two drops of a solution of sodium attestatio.

Through the analysis of spend control experience.

After subtracting the value of optical density of the solution in the reference experiment from the value of the optical density of the sample solution find the mass concentration of oxide manganese calibration curve

.

2.3.2. To build a calibration curve in eight of the nine conical flasks with a capacity of 100 cmis taken 0,5; 1,0; 2,0; 2,5; 3,0; 3,5; 4,0; 5,0 cmof solution B, which corresponds to 0,00005; 0,0001; 0,0002; 0,00025; 0,0003; 0,00035; 0,0004; 0,0005 g of oxide of manganese. In each flask poured with 20 cmwater, 10 cmof sulphuric acid (1:1), 5 cmof phosphoric acid, heated to boiling, poured 10 cmof the solution jednolitego of potassium and boiled for 5 min. Cooled solutions are poured into volumetric flasks with a capacity of 100 cm, made up to the mark with water and mix. Optical density of the solution is measured as indicated in claim 2.3.1. Solution comparison is the solution of the ninth flask containing a standard solution of protoxide of manganese.

According to the obtained values of optical densities and the respective mass proportions of oxide of manganese build a calibration curve

.

2.4. Processing of the results

2.4.1. Mass fraction of manganese oxide () in percent is calculated by the formula

,

 — the mass of the oxide of manganese in the solution of the sample, was found in the calibration schedule g;

 — the weight of the portion corresponding to aliquote part of the solution,

2.4.2. The absolute differences of the results of the parallel definitions should not exceed permissible values, specified in table.1.

Table 1

3. ATOMIC ABSORPTION METHOD

3.1. The essence of the method

The method is based on the fusion of sample with flux mixture for alloying, dissolution of salts, diluted hydrochloric acid, spraying the solution into the flame of air-acetylene and measuring the nuclear absorption of manganese at a wavelength of 279.5 nm in terms of oxide of manganese.

3.2. Apparatus, reagents and solutions

Spectrophotometer atomic absorption of any type.

Muffle furnace with heating temperature up to 1000 °C.

The container with the dissolved and gaseous acetylene according to GOST 5457−75.

The compressor with the receiver, providing a continuous flow of air pressure at the entrance to the spectrometer of at least 20 ATM.

Hydrochloric acid by the GOST 3118−77 and diluted 1:1, 5:95.

Sulfuric acid GOST 4204−77 and diluted 1:1.

Hydrofluoric acid according to GOST 10484−78.

Boric acid according to GOST 9656−75.

Potassium carbonate — sodium carbonate according to GOST 4332−76.

Mix for fusion of the two parts of potassium carbonate-sodium carbonate is mixed with one part boric acid.

Lanthanum nitrate, a solution of 50 g/DM.

Potassium preservatory according to GOST 7172−76.

Standard solution B, prepared according to claim 2.2.

3.3. Analysis

3.3.1. The linkage of flux with a mass of 0.5 g mixed in a platinum crucible with 5 g of a mixture for melting, sprinkle the top of the sample 0.5 g of the mixture. The crucible closed with a lid and melted first in the less hot zone, then kept at 950−1000 °C for 10 min, the Crucible is cooled.

The melt is transferred into a glass with a capacity of 400 cm. The crucible and the cover washed on a glass of 30 cmof hydrochloric acid (1:1), then hot water. Beaker cover watch glass, gently heated until complete dissolution of the alloy.

To the solution through the spout of the Cup poured 20 cmof sulphuric acid (1:1), watch glass and walls of beaker washed with hot water and evaporate the solution until the appearance of dense sulphuric acid fumes. Cool, the side of the Cup is washed with cold water and again evaporate the solution until copious fumes of sulfuric acid. The contents of the beaker cooled, poured 30 cmof hydrochloric acid, 100−150 cmof water and heated to dissolve the salts.

The solution was filtered through filter «blue ribbon» filter paper mass is washed 2−3 times with hot hydrochloric acid (5:95) and 3−4 times with hot water. The filter is placed in a platinum crucible, dried, ignited, the residue moistened with 2−3 drops of water, add 3−4 drops of dilute sulphuric acid, 3−5 cmhydrofluoric acid and evaporate the contents of the crucible to remove vapors of sulfuric acid, and calcined goplast with 1−1. 5 g of potassium peacemaking. The cooled crucible is placed in a beaker with a capacity of 250 cm, 50 cm pourhot water, 10 cmof hydrochloric acid and heated to dissolve the melt. Then the crucible is removed from the beaker, washed with water and connect the solution to the first filtrate. Transfer the solution into a volumetric flask with a capacity of 500 cm, cooled, adjusted to the mark with water and mix.

For fluxes with a mass fraction of manganese oxide of from 0.5 to 2.0% are undertaking further dilution. Aliquot part of the basic solution chosen at the table.2, is placed in a volumetric flask with a capacity of 100 cm, pour 4 cmof hydrochloric acid, made up to the mark with water and mix.

Table 2

Through the analysis of spend control experience.

Spray the solution in the reference experiment and the solution of the sample in the flame of air-acetylene and measure the absorbance of each solution in order of increasing absorption to obtain stable indicators for each solution.

Before spraying each solution is sprayed water to wash the system and check the zero point. Measure the atomic absorption of manganese at a wavelength of 279.5 nm in terms of oxide of manganese.

After subtracting the atomic absorption of the solution in the reference experiment from the value of atomic absorption of a solution of the sample mass to find the concentration of nitrous oxide of manganese in the solution of the analyzed sample according to the calibration schedule.

3.3.2. Construction of calibration curve

To build a calibration curve in five out of six volumetric flasks with a capacity of 100 cmpoured 1,0; 2,0; 3,0; 4,0; 5,0 cmstandard solution B, which corresponds to 0,0001; 0,0002; 0,0003; 0,0004; 0.0005 g of oxide of manganese.

For fluxes with a mass fraction of oxide of manganese from 0.1 to 0.5% in each flask pour 10 cmof lanthanum nitrate, at a mass proportion of from 0.5 to 2.0% in each flask pour 5 cmof lanthanum nitrate, pour 4 cmof hydrochloric acid, made up to the mark with water and mix. The sixth flask, containing a standard solution that is used for the reference experiment.

Measuring the absorbance of the resulting solutions is carried out as specified in clause 3.3.1.

3.4. Processing of the results

3.4.1. Mass fraction of manganese oxide () in percent is calculated by the formula

,

where - the mass of the oxide of manganese in the solution of the sample, was found in the calibration schedule g;

 — the weight of the portion corresponding to aliquote part of the solution,

3.4.2. The absolute differences of the results of the parallel definitions should not exceed permissible values, specified in table.1.