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钼蓝分光光度法联合测定铁矿石中磷和二氧化硅 预览

Combined determination of phosphorus and silicon dioxide in iron ore by molybdenum blue spectrophotometry
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摘要 以往铁矿石中磷和二氧化硅含量的测定需要分别采用钼蓝分光光度法。在使用磷钼蓝分光光度法时,常会因钒、砷等的干扰使得磷测定结果不准确,需要将样品再处理后才能测定。实验采用石墨垫底铁坩埚,碳酸钠和硼酸混合熔剂高温熔融铁矿石,使铁矿石样品分解彻底,再分别采用铋磷钼蓝和硅钼蓝分光光度法测定磷和二氧化硅含量,从而实现了采用钼蓝分光光度法联合测定铁矿石中磷和二氧化硅。干扰试验表明,在高温熔融时,石墨可将钒(V)还原为钒(III),使样品中钒不干扰磷的测定;显色液中加入15mg硫代硫酸钠溶液可将砷(V)还原为砷(III),继而消除砷对磷测定的干扰。磷的质量浓度在0~3μg/mL范围内遵守比尔定律,校准曲线的线性相关系数为0.999 9,表观摩尔吸光系数为2.242×104 L·mol-1·cm-1;二氧化硅的质量浓度在0~5μg/mL范围内遵守比尔定律,校准曲线的线性相关系数为0.999 5,表观摩尔吸光系数为9.342×103 L·mol-1·cm-1。方法中磷和二氧化硅的检出限分别为0.002 6μg/mL和0.008 1μg/mL。按照实验方法测定6个铁矿石标准样品中磷和二氧化硅,磷测定结果的相对标准偏差(n=8)小于5%,相对误差小于2%;二氧化硅测定结果的相对标准偏差(n=8)小于2%,相对误差小于1.5%。按照实验方法测定5个铁矿石样品中磷和二氧化硅,磷测定结果的相对标准偏差(RSD,n=8)小于7%,二氧化硅测定结果的相对标准偏差(n=8)小于1%;磷和二氧化硅的测定值均与电感耦合等离子体原子发射光谱法的测定值相一致。 In the past,the content of phosphorus and silicon dioxide in iron ore were determined separately by molybdenum blue spectrophotometry.When the phosphorus molybdenum blue spectrophotometry was used,the determination results of phosphorus were often inaccurate due to the interference by vanadium and arsenic.As a result,the sample should be retreated before determination.With bottom of iron crucible covered by graphite,the iron ore was melted at high temperature with sodium carbonate-boric acid mixture as flux.After complete decomposition,the content of phosphorus and silicon dioxide in iron ore sample was determined by bismuth phosphorus molybdenum blue spectrophotometry and silicon molybdenum blue spectrophotometry,respectively.Therefore,the combined determination of phosphorus and silicon dioxide in iron ore by molybdenum blue spectrophotometry was realized.The interference test indicated that vanadium(V)was reduced to vanadium(III)by graphite during the melting at high temperature,which eliminated the interference of vanadium with the determination of phosphorus.15 mg of sodium thiosulfate solution was added into the coloring solution to reduce arsenic(V)to arsenic(III),which eliminated the interference of arsenic with the determination of phosphorus.Beer′s law was obeyed for phosphorus with mass concentration in the range of 0-3μg/mL.The linear correlation coefficient of calibration curve was 0.999 9.The apparent molar absorptivity was 2.242×104 L·mol-1·cm-1.Beer′s law was obeyed for silicon dioxide with mass concentration in the range of 0-5μg/mL.The linear correlation coefficient of calibration curve was 0.999 5.The apparent molar absorptivity was 9.342×103 L·mol-1·cm-1.The detection limit of phosphorus and silicon dioxide in this method was 0.002 6μg/mL and 0.008 1μg/mL,respectively.The contents of phosphorus and silicon dioxide in six certified reference materials of iron ore were determined according to the experimental method.The relative standard deviations(RSD,n=8)of determination results
作者 王鹏辉 金留安 WANG Peng-hui;JIN Liu-an(Kunming Iron and Steel Holding Co.,Ltd.Quality and Metrology Testing Center Anning Quality Inspection Station,Anning 650302,China)
出处 《冶金分析》 CAS 北大核心 2019年第3期58-64,共7页 Metallurgical Analysis
关键词 铁矿石 二氧化硅 联合测定 钼蓝分光光度法 iron ore phosphorus silicon dioxide combined determination molybdenum blue spectrophotometry
作者简介 王鹏辉(1966—),男,高级工程师,主要从事进厂铁矿石、原燃料质量检验工作;E-mail:TYWPH@163.com
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