水玻璃旧砂再生脱膜率评价方法初探

Discussion on Evaluation Methods of Reclamation Scrubbing Ratio for Used Sodium Silicate Sands

现有的水玻璃旧砂再生脱膜率采用砂中Na2O总含量进行评价,一般通过酸碱滴定方法直接测定。水玻璃旧砂表面粘结膜主要有碳酸钠、草酸钠、乙酸钠及模数不同的水玻璃等组分,其主要化学组成随固化方法和工艺的不同,有着明显的差异,各组分对再生砂性能的影响还未获得统一认识,且脱膜过程中各组分的脱除程度也不一样。可见,仅用Na2O总含量评价水玻璃砂再生脱膜率不全面,也不能完全反映再生砂的性能。针对现有测试Na2O的方法存在的准确度低等问题,文章概述了已有改进的Na2O测试方法,并给出了改变现有再生脱膜率评价方法的建议,主要包括在系统研究残留粘结膜各组分对再生砂性能影响的基础上,并结合再生方法的特点,综合考察粘结膜各组分的脱除程度,以实现再生脱膜率和再生砂的综合性能全面和准确的评价。

The components of remnant binder on the surface of used sodium silicate sands varies with curing methods, they affect the performs of mold sands differently. Some Components can be dissolved in water easily, others can be dissolved little. The scrubbing ratio of different reclamation methods are not the same. The exsiting testing method for judging the scrubbing ratios of reclamation, by total Na20 content in remnant binder through titration, can not characterize the properities of reclamation sands distinctly, and the accuracy of this method is not good. The suggestion is proposed that the components of remnant binder, such as sodium carbonate, sodium dicarboxyl, sodium acetate, and so forth, should be analysed separately in order to evaluate the performs of reclaimed sands and the reclamation ratio of the used sands.