酸溶高氯酸脱水重量法测定镁砂中二氧化硅  

Determination of silicon dioxide in magnesia by perchloric acid dehydration gravimetric method with acid dissolution

作　　者：徐建平[1] 王洪红[1] 

机构地区：[1]武汉科技大学,湖北武汉430081

出　　处：《冶金分析》2013年第4期57-60,共4页Metallurgical Analysis

摘　　要：探讨酸溶高氯酸脱水重量法测定镁砂中二氧化硅的测定条件。1g的样品用10mL盐酸溶解后,高氯酸用量只需要10mL。分别以硫酸和硝酸为驱赶酸进行硅挥散试验,发现以硝酸为驱赶酸时,残渣挥硅失重与残渣中SiO2的量一致,而以硫酸为驱赶酸后SiO2的测定结果偏低。挥散硅后的残渣用无水碳酸钠和硼酸混合熔剂(m碳酸钠∶m硼酸=2∶1)熔融、盐酸浸取,用电感耦合等离子体原子发射光谱法(ICP-AES)测定,发现其主要成分为MgO。为避免高分解温度的MgF2生成,F-必须驱赶尽;同时以ICP-AES测定滤液中SiO2含量,发现没有凝聚的SiO2含量小于样品中总SiO2量的0.3%(相对量),因此高氯酸一次脱水即可。对不同等级的镁砂标准样品(待发布)进行测定,结果与标准值相吻合,结果的相对标准偏差(RSD)为1.2%,0.93%和0.45%。方法较碱熔法简化了操作。The testing condition of determining silicon dioxide in magnesia by perchloric acid dehydra-tion gravimetric method with acid dissolution was proposed. After 1 g sample was dissolved by 10 mL hydrochloric acid, only 10 mL perchloric acid was applied for the test. Sulfuric acid and nitric acid were used separately as expulsion acid for silicon vaporization test. It was found that when nitric acid was used as expulsion acid, the weight loss of silicon was the same as SiO2 in the residue while sulfuric acid was used as expulsion acid, the testing result of SiO2 was lower. The residue after the volatiliza- tion of silicon was melted by anhydrous sodium carbonate and boric acid mixed flux （m_sodium carbonate：m_boric acid =2 ： 1） and leached by hydrochloric acid,then ICP-AES was used for determination. It was found its major component was MgO. To prevent the production of MgF., which had high decomposi- tion temperature, F must be expelled. Meanwhile, ICP-AES was used to determine SiOo in filtrate. It was found the content of non-aggregated SiO2 was 0.3% （relative amount） lower than the total SiO2 in the sample. Thus, hydrochloric acid can be dehydrated just for one time. Testing was conduc- ted on different level of magnesia standard sample （to he released）. The result was consistent with the candidate certified value with the RSD of 1.2%, 0.93% and 0.45%, respectively. The method had simplified operation compared with that of alkali fusion.

关 键 词：二氧化硅 重量法 镁砂 酸溶解 

分 类 号：P575.3[天文地球—矿物学] O655.2[天文地球—地质学]