红外光谱法测定石英砂中游离二氧化硅含量的影响因素分析

目的 通过用红外光谱法测定石英砂游离二氧化硅含量过程中影响因素的分析,提出适宜石英砂的二氧化硅检测方法.方法 运用红外光谱法测定石英砂中游离二氧化硅含量,并对研磨时间、灰化温度、灰化时间等影响因素进行分析研究,并与焦磷酸法进行比较.结果 随着研磨时间的延长,小于5μm的微粒增多,游离二氧化硅含量也相应增高,研磨到15～20 min时,游离二氧化硅含量的测定结果趋于稳定.灰化温度在550℃以下对游离二氧化硅含量无影响;与灰化温度550℃时比较,灰化温度600℃时的二氧化硅含量降低,但差异无统计学意义(P＞0.05).当灰化温度在600℃时,灰化时间在1 h内石英砂样品中的游离二氧化硅含量无明显变化,差异无统计学意义(F值=4.231,P值＞0.05).与灰化1 h的样品比较,灰化2 h时石英砂样品中的游离二氧化硅含量明显降低,差异有统计学意义(F值=10.231,P＜0.05).焦磷酸法测定游离二氧化硅含量平均为88.56%±5.75%,红外法测定游离二氧化硅含量平均为21.23%±11.25%,两者的差值为51.42%～86.52%,差异有统计学意义,(t=29.177,P＜0.05).红外法与焦磷酸法测定游离二氧化硅含量无相关性(r=0.411,P=0.072).结论 焦磷酸法测定石英砂游离二氧化硅含量结果明显高于红外法.建议石英砂中游离二氧化硅测定方法首选焦磷酸法.

Analysis of influencing factors on infrared spectroscopic determination of the content of free silica in quartz sand

Objective To find a suitable method for detecting SiO2 in quartz sand and to analyze the influencing factors on infrared spectroscopic determination of the content of free silica in quartz sand.Methods The infrared spectroscopy was used to detect the free silica content of quartz sand, the various factors of influencing the results were analyzed and the control scheme was proposed.Results The number of particles less than 5um and the proportion of free silica content increased with the grinding time.When the grinding time was 10～20 min, the results of detecting the free silica content tended to be stable.When the ashing temperature was below 550 ℃, there was no effect on the free silica content.Although the silica content decreased slightly at ashing temperature 600 ℃as compared to ashing temperature 550℃, the difference of the free silica content between 550℃ and 600℃ was not significant (P＞0.05).When the ashing temperature was 600℃, the free silica content in quartz sand samples did not change obviously in 1 h (F=4.231, P＞0.05).The free silica content in quartz sand samples decreased significantly at 2 h of ashing time, as compared with 2 h of ashing time (F=10.231, P＜0.05).The average content of free silica was 88.56% ± 5.75% by pyrophosphate determination,which was significantly higher than that (21.23% ± 11.25%) by infrared determination (P＜0.05).There was no significant correlation of the average content of free silica between pyrophosphate determination and infrared determination (r=0.411, P＞0.05).Conclusion The free silica contents detected by pyrophosphate determination were significantly higher than those detected by infrared determination for the same quartz sand samples.It is suggested that the method of detecting the free silica contents in quartz sand samples prefers the pyrophosphate determination to infrared determination.