GOST 16412.5-91
GOST 16412.5−91 iron Powder. Methods of determining sulphur
GOST 16412.5−91
Group B59
STATE STANDARD OF THE USSR
IRON POWDER
Methods of determining sulphur
Iron powder.
Methods for the determination of sulphur
AXTU 0809
Date of introduction 1992−07−01
INFORMATION DATA
1. DEVELOPED AND INTRODUCED by the Academy of Sciences of the Ukrainian SSR
DEVELOPERS
V. N. Klimenko, PhD. tech. Sciences; A. E. kushchevsky, PhD. chem. Sciences; V. A. Dubok, PhD. chem. Sciences (head of subject); V. I. Kornilov, candidate. chem. Sciences; V. V. Garbuz, PhD. chem. Sciences; L. D. Bernatsky
2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee on management of quality and standards from
3. REPLACE GOST 16412.5−80
4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document referenced | Paragraph number section |
| GOST 3118−77 | 2.2 |
| GOST 4202−75 | 2.2 |
| GOST 4232−74 | 2.2 |
| GOST 5583−78 | 2.2 |
| GOST 9147−80 | 2.2; 3.2 |
| GOST 10163−76 | 2.2 |
| GOST 16539−79 | 3.2 |
| GOST 20490−75 | 2.2 |
| GOST 24363−80 | 2.2 |
| GOST 28473−90 | Sec. 1 |
This standard establishes titrimetric (mass fraction of sulfur at 0.005 to 0.05%) and coulometric (with the mass fraction of sulfur from 0.002 to 0.20%) methods for the determination of sulfur in iron powder.
1. GENERAL REQUIREMENTS
General requirements for methods of analysis GOST 28473.
2. TITRIMETRIC METHOD FOR THE DETERMINATION OF SULFUR
2.1. The essence of the method
The method is based on the combustion of a sample of iron powder in an oxygen flow at a temperature of 1300−1350 °C. the Formed sulfur dioxide is displaced by the flow of oxygen in the absorption vessel and is absorbed in this water, resulting in sulphurous acid, which octarepeat mixture odnomodovogo and potassium iodide in the presence of starch indicator.
2.2. Apparatus, reagents and solutions.
Setup for the determination of sulfur, shown in the drawing, consists of a oxygen cylinder 1 provided with a pressure reducing valve and pressure gauge for start-up and regulation of oxygen flow 2; absorption flask 3 containing a solution of potassium permanganate with a mass fraction of 40%, to clean oxygen coming into the oven; U-shaped tube 4, which in the first half (in the direction of oxygen) soda lime and the second calcium chloride; tap to regulate the flow of purified oxygen 5; mullite refractory tube 6 an inner diameter defined by the diameter of the used gate and the size of the boat. The ends of the tube protruding from the furnace, must be at least 250 mm. Tube before use, should be burnt along the entire length at a temperature of 1300−1350 °C in an oxygen flow; a horizontal tubular furnace 7 with a silicon carbide heater that provides heating to 1300−1350 °C, the thermostat 8, which maintain constant temperature furnace; voltage regulator 9 (allowed to use other types of kilns that provides the required temperature); dust collector 10; two-way tap 11, the absorber 12 consisting of two glass vessels with an internal diameter of 30−35 mm and a height of 150 mm, connected by glass bridges, the bottom of which there is a tap for draining the liquid at the end of the analysis. In the left vessel sink included l-shaped tube through which passes a stream of oxygen and sulfur dioxide that ends barbaram sputtering gases for better absorption of sulfur dioxide with water. In the left vessel are absorbed sulphur dioxide, and titration of the resulting solution of sulphurous acid, in the right during the titration is a solution for comparison of color; 13 burettes with a capacity of 25 cm.
Muffle furnace type SNOL according to normative-technical documentation or any other type providing a heating temperature not lower than 900 °C.
The hook with which the boat is introduced into the tube for flaring and extracted from it, is made of heat-resistant low-carbon wire with a diameter of 3−5 mm and a length of 500−600 mm.
Boat porcelain with GOST 9147, calcined at temperatures below 900 °C for 6 h or at operating temperature in a stream of oxygen for 2−3 min.
Boats stored in the desiccator, socket covers which do not cover the lubricant. The completeness of burning of sulfur and its compounds from boats is controlled by passing the gaseous products from the furnace through iodobromine solution. The end of burning sulphur is determined by the cessation of bleaching iodobromine solution.
Oxygen gas according to GOST 5583.
Potassium ignominously according to GOST 4202.
Potassium hydroxide according to GOST 24363, a solution with a mass fraction of 4%.
The lime soda.
The calcium chloride.
Potassium iodide according to GOST 4232.
Titrated a solution of a mixture odnomodovogo of potassium and iodide of potassium; 0,0862 g odnomodovogo potassium, 2 g of potassium iodide and 0.4 g of potassium hydroxide were placed in a glass and dissolve in 1 DMof water. The solution was stored in a flask made of dark glass. 1 cm
of the mortar is 0,000062 g of sulfur. The mass concentration of the mixture odnomodovogo of potassium and iodide of potassium set at a standard piece of steel, similar in chemical composition and mass fraction of sulfur to analyze the iron powder. When determining the mass fraction of sulfur less than 0.01% of the titrated solution was diluted in a ratio of (1:4), (1:6).
Mass concentration of solution (), expressed in grams of sulfur per 1 cm
of a solution, calculated by the formula
where — mass fraction of sulfur in the standard sample, %;
— weight of standard sample, g;
— the volume of the mixture solution odnomodovogo and potassium iodide; used for titration of standard solution of the sample, cm
;
— the volume of the mixture solution consumed for titration of the solution in the reference experiment, cm
.
Potassium permanganate according to GOST 20490, solution with a mass fraction of 4% solution of potassium hydroxide with a mass fraction of 40%.
Hydrochloric acid according to GOST 3118.
The soluble starch according to GOST 10163, solution with a mass fraction of 0.05%; 0.5 g soluble starch, triturated in a porcelain mortar with 50 cmof water and pour the slurry in a thin stream at 950 cm
. of boiling water. To the obtained solution poured 15 cm
of hydrochloric acid. Use freshly prepared solution.
Copper oxide according to GOST 16539 powdered or granulated, calcined at a temperature of (800±25) °C for 3−4
h
2.3. Preparation for assay
Before analysis, the installation must be checked for tightness at a temperature of 1300−1350 °C. connect the installation to the container, open the container and allow oxygen at a rate of 2 DM/min Tap switch 5 so that the oxygen enters the oven. The faucet 11 is closed. After 2 min should stop the bubbling of the absorption flask 3. If after 5 min, the bubbles do not stand out, consider installing tight. Then determine the presence of reductive substances in the tube and the boat for the combustion of the sample. For this, each vessel sink is poured on 120 cm
of starch solution is poured from the burette a few drops of the titrated solution mixtures odnomodovogo and potassium iodide before the appearance of blue color and let the oxygen flow with such speed that the liquid level in the absorption vessel has risen by 30−40 mm. If starch solution in the absorption vessel after some time, become colourless, indicating the selection of the restorative porcelain tube of gaseous substances, without stopping oxygen flow to the absorption solution is added from burette a solution of a mixture of potassium iodide and odnomodovogo until while the intensity of the color in the left and right parts of the absorber will not be the same.
2.4. Analysis
A suspension of iron powder weighing 1 g is placed in a porcelain boat and cover the top evenly with a layer of cuprous oxide (1 g). Boat with iron powder and copper oxide was placed in the most heated portion of the porcelain tube, the tube is closed immediately with a rubber stopper with a glass tube or valve through which the withdrawn gaseous products of the combustion into the absorption vessel and produce combustion. Oxygen should be flowing at a rate of 2 DM/min to prevent the formation of vacuum in the furnace. When leaving the furnace in the absorption vessel gases begin to discolor the solution, a solution mixture of potassium iodide and odnomodovogo with such speed that the color of the solution in the left part of the absorber close to the color of the solution comparison. The titration is complete when the color intensity of the solutions in both vessels are equal. After that, the oxygen flow 1 min. If the color of the solution does not change, the combustion is complete.
2.5. Processing of the results
2.5.1. Mass fraction of sulfur () in percent is calculated by the formula
where is the volume of solution of a mixture odnomodovogo and iodide of potassium consumed in the titration of a solution of test sample, cm
;
— the volume of the mixture solution odnomodovogo and potassium iodide consumed for titration of the solution in the reference experiment, cm
;
— mass concentration of a solution of a mixture odnomodovogo and potassium iodide; expressed in g/cm
;
— weight of iron powder, g
.
2.5.2. Allowable absolute differences of the results of the parallel definitions should not exceed the values given in the table.
| Mass fraction of sulfur, % | Allowable absolute differences, % |
| From 0.002 to 0.005 incl. | 0,0013 |
| SV. 0,005 «0,010 « | 0,0017 |
| «0,010» 0,020 « | 0,0025 |
| «0,020» 0,050 « | 0,0040 |
| «0,050» 0,100 « | 0,0070 |
| «0,100» 0,200 « | 0,0100 |
3. COULOMETRIC METHOD FOR THE DETERMINATION OF SULFUR
3.1. The essence of the method
The method is based on the combustion of a sample of iron powder in an oxygen flow at a temperature of 1300−1350 °C. the Formed sulfur dioxide is absorbed by the absorptive solution and causes an increase of acidity and the change in the EMF indicator system pH meter.
The quantity of electricity necessary to achieve the initial pH of the absorbing solution is proportional to the concentration of sulfur in the sample, fixed colorometer integrator current, showing the amount of sulfur in percent. The effect of carbon avoided by selecting the initial pH value of absorption solution at the pH of 3.9. At this acid the absorption solution is practically not absorbed by the carbon dioxide produced by the combustion of sample carbon, and the sulfur dioxide is absorbed completely.
3.2. Apparatus, reagents and solutions
Coulometric installation of any type complete with all accessories (comonomer, absorption vessels, pH meter, corrector mass) for the precision of the analyses specified in the table. The weight set depending on the type of installation.
A horizontal tubular furnace with silicon carbide heaters, ensure the temperature of 1300−1350 °C.
Tube refractory mullite.
Muffle furnace type SNOL according to normative-technical documentation or any other type providing a heating temperature not lower than 900 °C.
Boat porcelain with GOST 9147, calcined at temperatures below 900 °C for 6 h or at operating temperature in a stream of oxygen for 2−3 min.
Boats stored in the desiccator, socket covers which do not cover the lubricant.
Absorption and support the solutions prepared in accordance with the type of the used coulometric setup.
Copper oxide according to GOST 16539, powdered or granulated, calcined at a temperature of (800±25) °C for 3−4 h.
3.3. Analysis
Device prepare to work in accordance with the instructions. To remove traces of sulfur from the unit before starting the analysis through the installation flow, the flow of oxygen and calcined up.
The weight of iron powder with a mass of 0.5−1 g is transferred into a porcelain boat, pour a uniform layer of copper oxide mass of 1 g, placed the boat with the hitch in the most heated portion of the porcelain tube and quickly close the tube with stopper. Click on the «reset» button and set the display indication the digital display to «zero». Burn a portion of iron powder, flow of oxygen at a temperature of 1300−1350 °C. After complete combustion of the sample of iron powder in what is judged by the completion of the titration, record the result of the analysis by reading the digital display, open the stopper and remove the boat.
3.4. Processing of the results
3.4.1. Mass fraction of sulfur () in percent is calculated by the formula
where — reading digital display of the device, the resulting combustion of the sample of the sample, %;
— the arithmetic average of the readings of the digital display device, resulting from the burning flux when conducting control experiments, %.
3.4.2. Allowable absolute differences of the results of the parallel definitions should not exceed the values given in the table.
