Determination of Carbonates in Converter Slag by Using Carbon Dioxide Detector Tube

We modified a rapid method for determining carbonate content and applied to some iron and steel slags. One gram of pulverized slag sample is weighed into an air-tight plastic bag fitted with stop cock and heat-sealed. The bag is evacuated to remove air, 35 mL of 0.7 mol/L iron(III) chloride and 200 mL of air are introduced through the stop cock and the contents are allowed to react for 20 min with occasional shaking. Carbon dioxide content of the air inside the bag is determined with the aid of carbon dioxide detector tube. The carbonate content of the sample is calculated by summing the amount of carbon dioxide in the air phase and that dissolved in the solution, the latter is calculated by using the Henry’s law. The method was successfully applied to an air aged converter slag sample and samples taken from slag-paved woodland paths. The carbonate content ranged from 0.26 to 0.83 mol/kg. The paving materials that had been exposed to the atmospheric air and soil air contained more carbonate.