Determination of carbonate content in sodium silicate-bonded sand by gas volumetry
The property of reclaimed sodium silicate-bonded sand was greatly affected by the carbonate,so its content should be quantitatively analyzed.10-50 g of sample was decomposed with 0.50 mol/L hydrochloric acid.The volume of generated carbon dioxide in reaction was collected and measured using the eudiometer.The reaction time was controlled to be higher than 18 min.The reaction endpoint was the time that when the liquid level in eudiometer was changeless within 3-5 min.The content of carbonate was calculated according to the volume of carbon dioxide gas.Based on this,the determination method of carbonate content in sodium silicate-bonded sand by gas volumetry was established.The proposed method was applied to the determination of carbonate content in simulated sodium silicate-bonded sand sample,and the found results were consistent with the theoretical values.The relative standard deviation (RSD) was 0.20 %-0.80 %.The proposed method was used to determine the content of carbonate in old and reclaimed sodium silicate-bonded sand samples.The found results were basically consistent with those obtained by titration method.The RSD was not higher than 0.91%.