气体容量法测定水玻璃砂中碳酸盐含量

水玻璃再生砂中的碳酸盐对其性能有较大影响,需进行定量分析。用0.50 mol/L盐酸分解10～50 g试样后,用量气管收集并测量反应生成的二氧化碳气体体积,反应时间控制在18 min以上,当量气管液面高度在3～5 min内不变时为反应终点,根据二氧化碳气体体积计算碳酸盐含量,建立了气体容量法测定水玻璃砂中碳酸盐含量的方法。方法用于水玻璃砂模拟样品中碳酸盐含量的测定,测定值与理论值一致,相对标准偏差在0.20%～0.80%之间;用于水玻璃旧砂和再生砂中碳酸盐含量的测定,测得结果与滴定法基本吻合,相对标准偏差不大于0.91%。

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%.