Review of Methods for the Determination of Carbon and Sulfur (2)

1.3 Non-aqueous carbon determination and potassium iodate volumetric method for sulfur determination

The method is to put the sample in the ceramic boat, add appropriate amount of flux, the ceramic boat will be pushed into the combustion furnace high-temperature area (1200-1250℃) preheating 0.5-1 min, oxygen combustion (oxygen flow rate of 1-2L/min) to generate SO2, CO2 gas, through the dust pipe into the sulfur, carbon absorption cup, when the starch absorbent solution in the pure blue gradually fade, then KIO3 solution, alkaline non-aqueous solution titration of sulfur, carbon, near the end point, intermittent oxygen 1-2 times, continue to titrate to the solution of non-aqueous carbon and potassium iodate volumetric method, and continue to titrate to the solution of sulfur, carbon and potassium iodate volumetric method, and the method of sulfur and potassium iodate volumetric method is to be used to determine sulfur, carbon and non-aqueous carbon and non-water solution. When the pure blue color in the starch absorbent gradually fades, then titrate the sulfur and carbon with KIO3 solution and alkaline non-aqueous solution, near the end point, intermittently pass the oxygen for 1-2 times, and continue the titration to the end point of the original pure blue color of the solution. According to the number of milliliters of KIO3 standard solution and alkaline non-aqueous solution consumed and the titration degree obtained from the corresponding standard specimen, the content of sulfur and carbon is calculated. Non-aqueous titration of carbon is the standard method for the determination of carbon in carbon steel and high, medium and low alloy steel (WM3012-87).

Potassium iodate volumetric method is the standard method for the determination of sulfur in pig iron powder, carbon steel, alloy steel, high-temperature alloys, precision alloys, antimony and silver. The method was widely used in China in the 1970s and 1980s. Titration is a very simple manual operation, but it is difficult to automate the titration. Through the efforts of our analysts, we have developed our own automated instrument, which realizes automatic addition of liquid, automatic titration, automatic determination of titration endpoint, automatic printing and digital display of carbon and sulfur determination results.

1.4 Carbon and Sulfur Determination by Conductivity Method

Conductivity method to determine the amount of carbon, sulfur is the combustion method of CO2 and SO2 gas mixture is first introduced into the sulfur conductivity absorption cell, the cell contains an acidic oxidant sulfur absorbing liquid (commonly used oxidants such as KIO4, H2 O2, etc.), SO, oxidation and the production of H₂SO4, resulting in an increase in the concentration of absorbing liquid hydrogen ions, and its value-added and the sulfur content of the proportionality of, and then by the computer processing, you can display and print out the sulfur content. Conductivity method of carbon measurement is to have absorbed SO2 gas mixture and then introduced into the carbon absorption pool, the absorption pool is equipped with a solution that can absorb CO2 (such as NaOH, Ba (OH)2, etc.), when the introduction of CO2, the conductivity of the solution changes, the value of the change is directly proportional to the amount of CO2, by the computer, can be displayed and printed out the content of carbon. The whole process is completed automatically, and the time is 60s.

The conductivity method for determining carbon and sulfur is characterized by accuracy, speed and sensitivity. It is mostly used for the determination of low carbon and low sulfur. The lower limit of determination is good.

The conductivity method is a standard method for the determination of tungsten powder, tungsten trioxide, tungstic acid, molybdenum powder, molybdenum trioxide, ammonium molybdate and other trace sulfur.