GOST 21639.10-76

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  ГОСТ 21639.10-76

GOST 21639.10−76 Fluxes for electroslag remelting. Method for the determination of sulfur (with Amendments No. 1, 2)

GOST 21639.10−76

Group B09

STATE STANDARD OF THE USSR

FLUXES FOR ELECTROSLAG REMELTING

Method for the determination of sulfur

Fluxes for electroslag remelting. Method for determination of sulphur

AXTU 0709

Date of introduction 1977−07−01

INFORMATION DATA

1. APPROVED AND promulgated by the Decree of the State Committee of standards of Ministerial Council of the USSR from March 10, 1976 N 662

Change No. 2 adopted by the Interstate Council for standardization, Metrology and certification (Protocol No. 9 dated April 12, 1996)

The adoption voted:

2. INTRODUCED FOR THE FIRST TIME

3. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

4. Limitation of actions taken on the Protocol, the Interstate Council for standardization, Metrology and certification (ICS 2−93)

5. REVISED (March 1998) with Amendments No. 1, 2 approved in November 1986, August 1996 (IUS 2−87, 11−96)


This standard specifies the titrimetric method for the determination of sulfur in fluxes when the mass fraction of its 0.005 to 0.07%.

(Changed edition, Rev. N 2).

TITRIMETRIC METHOD

The method is based on the combustion of the flux linkage in a current of oxygen in a tube furnace at a temperature of 1300−1350 °C, the absorption of the formed sulphur dioxide with water and subsequent titration of sulphurous acid solution odnomodovogo potassium in the presence of an indicator-starch.

(Changed edition, Rev. N 1).

1. GENERAL REQUIREMENTS

1.1. General requirements for method of analysis according to GOST 21639.0.

2. APPARATUS, REAGENTS AND SOLUTIONS

Installation for determination of sulfur content (see drawing).

Installation for determination of sulfur content consists of the following elements: oxygen cylinder 1 provided with a pressure reducing valve for starting and regulating the current of oxygen; Tishchenko flask 2 containing a solution of potassium permanganate in a solution of 300 g/DMof potassium hydroxide; the flask Tishchenko 3 filled with concentrated sulfuric acid; 4 drying column filled with soda lime; double tap 5 for start-up of oxygen in the furnace; a horizontal tube furnace 6 silicafume heaters, providing heating to a temperature (1400±20) °C; thermocouple platinum-rhodium 7 with thermostat or millivolt type MRSPR-54; transformer 8 to regulate the voltage with an ammeter with a scale 20 And for controlling the amperage of the heater (you can use the type autotransformer RNO-250−10); unglazed porcelain tube 9 with a length of 650−750 mm, an inner diameter of 20−22 mm. the ends of the tube protruding from the furnace, must have a minimum length of 170−200 mm. the New handset before use, should be burnt at the operating temperature throughout its length. Tubes on both sides close well-fitting rubber stoppers. In hole insert glass tubes or brass tubes. To prevent burning the rubber tubes of the inner end surface of the closed asbestos gaskets; rings of tube 11, is filled with glass wool to trap solid particles of a flux, carried by a current of oxygen during combustion of the sample; an absorption vessel 12, consisting of two glass vessels connected by glass bridges (in one of the vessels soldered l-shaped glass tube ending barbaram, through which receives the gaseous products of the combustion into the absorption vessel) with a faucet at the bottom to drain the solution. To the right the vessel (vessel) pour the liquid, which serves for control; burettes for titration 13; bottles of dark glass 14 with a titrated solution of potassium odnomodovogo.

The hook is made of heat-resistant wire.

Potassium iodide according to GOST 4232.

Potassium hydroxide according to GOST 24363, solutions with a mass concentration of 40, 300 g/DM.

Potassium permanganate according to GOST 20490, solution with a mass concentration of 40 g/DMin the solution with a mass concentration of 300 g/DMof potassium hydroxide.

Calcium chloride, on the other 6−09−4711.

The lime soda.

The beach: oxide copper (II) in the form of powder according to GOST 16539. The beach needs to be checked for sulfur content. The amendment must not exceed 0.002 per cent of sulphur.

The soluble starch according to GOST 10163; solution with a mass concentration of 0.5 g/lis prepared as follows: 0.5 g of soluble starch was ground in a mortar with 30 cmof cold water, pour in a thin stream into the flask, where 700 cmof hot water. The solution was boiled for 2−3 min, cooled, poured 15 cmof hydrochloric acid and dilute with cold water to 1000 cm.

Hydrochloric acid according to GOST 3118.

Potassium ignominously according to GOST 4202.

Titrated solution of potassium odnomodovogo; prepared as follows: 0,0862 odnomodovogo g of potassium is dissolved in 300 cmof water, poured 10 cmof a solution with a mass concentration of 40 g/DMof potassium hydroxide and stirred. To the obtained solution was added 15 g of potassium iodide, and dissolve while stirring and add water in a volumetric flask to 1000 cm. The solution was stored in a flask made of dark glass. The mass concentration of a solution of potassium odnomodovogo set on hanging the standard sample and the flux conducted through all stages of the analysis.

The mass concentration of a solution of potassium odnomodovogo (), expressed in g/cmsulfur, calculated according to the formula

,

where  — mass fraction of sulfur in the standard sample, %;

 — weight of standard sample, g;

the volume of the solution odnomodovogo potassium, used for titration of the test solution, cm;

the volume of the solution odnomodovogo potassium consumed for titration of the solution in the reference experiment, cm.

Pumps porcelain N 2 according to GOST 9147 or corundum. Before using pumps and calcined in flowing oxygen 5 minutes at a temperature of 1300−1350 °C.

The food glass, laboratory for GOST 9932.

(Changed edition, Rev. N 1, 2).

3. PREPARATION FOR ASSAY

Before starting, heat the oven to a temperature of 1350 °C and check the installation for leaks. For this purpose in the absorption vessel and the vessel pour on a comparison 110−120 cmstarch solution, in which pre-add a few drops of the titrated solution of potassium odnomodovogo until the light-blue color. With tubes and rubber tubes connect all parts of the unit and allow oxygen with such speed that the liquid level of the absorber has risen by 30−40 mm. Then close the oxygen absorption vessel (with a clamp) and check the installation for leaks. The installation is sealed, if the absorption bottle after some time will stop the appearance of gas bubbles. If the bubbles are, then you need to change and porcelain connecting pipes, clean the valves, grease vacuum grease and re-check the installation for leaks.

Before analysis, remove the impurity of sulfur from porcelain pipes and pumps by calcination in flowing oxygen at the operating temperature of the furnace. Pumps placed in the hot portion of the tube and pass a current of oxygen at a rate of 2.5−3 DM/min. the Completeness of burnout of sulfur is controlled by passing the gaseous products through a starch solution containing potassium ignominously. As the bleaching solution added to titrated solution of potassium odnomodovogo to stable light blue color. The end of burning sulphur is determined by the termination of the bleaching solution.

Calcined boats stored in a desiccator. The solution from the absorption vessel and vessel comparison drained and rinsed the container with water.

To check the correct operation of the installation burn 2−3 sample standard sample flux according to the method specified in sec. 4. Then burn the flux to establish amendments the reference experiment.

4. ANALYSIS

Weighed flux of mass 1 g is placed in a porcelain boat, covered with flux in the ratio 1:2 (copper oxide). In the absorption vessel in advance is poured on 120 cmstarch solution, in which pre-add 3−4 drops of the titrated solution of potassium odnomodovogo until the light-blue color and allow oxygen at the rate of 2.5 DM 3/min. If there is a weakening of the color of the solution in the absorber, then add from burette dropwise titrated solution of potassium odnomodovogo to equalize coloration in both vessels. A boat with suspension and a smoother with a hook placed in the hottest part of the porcelain tube. The tube is closed with a rubber stopper. The sample is heated in an oven for 1 min without oxygen, then the oxygen flow with such speed that the liquid level in the absorber has risen by 30−40 mm. When leaving the furnace in the absorption vessel, sulphur dioxide begins to decolorize the solution from the burette is poured dropwise a solution of potassium odnomodovogo with such speed that the blue colour of the solution did not disappear during burning. The titration is complete when the color intensity of the solutions in both vessels is the same. To verify the completeness of combustion of sample oxygen flow for 1 min. If the color intensity is not reduced, the determination is complete, if it decreases, the titration continue. After burning a test portion of the boat hook is removed from the furnace, the solution is decanted from the absorption vessel and wash vessel with water. For the correction of the reference experiment burn two parallel linkage flux.

5. PROCESSING OF THE RESULTS

5.1. Mass fraction of sulfur () in percent is calculated by the formula

,

where is the mass concentration of the solution odnomodovogo potassium, expressed in g/cmsulfur;

the volume of the solution odnomodovogo potassium, used for titration of the test solution, cm;

the volume of the solution odnomodovogo potassium consumed for titration of the solution in the reference experiment, cm;

 — the weight of the portion,

(Changed edition, Rev. N 1).

5.2. Norms of accuracy and norms of accuracy control of determination of sulphur mass fraction given in the table.

(Changed edition, Rev. N 2).

Sec. «Method of automatic analyzers». (Deleted, Rev. N 2).