铜精矿中二氧化硅含量的快速测定

采用碱熔样硅钼蓝分光光度法测定铜精矿中二氧化硅的含量。讨论了熔融条件、吸收波长、溶液酸度、水浴加热时间、显色时间以及共存离子干扰等条件对测定结果的影响。确定以氢氧化钠为熔剂,在680℃熔融15 min,熔样效果最佳;根据样品中二氧化硅的含量选择波长,当二氧化硅含量小于1%时,选用810 nm为分析波长,二氧化硅含量为1%~15%时,选用650 nm为分析波长;在酸度为0.15~0.20 mol/L盐酸溶液中,水浴加热60 s,显色15min,显色效果为最佳。使用硫酸亚铁铵作为还原剂。方法的加标回收率在94.8%~98.8%之间,5个样品独立测定结果的相对标准偏差为0.26%~4.48%(n=11),标准样品测定结果与标准值吻合。该方法简单、快速、准确,适用于铜精矿中二氧化硅含量的测定。

Rapid Determination of Silicon Dioxide Content in Copper Concentrate

Content of silicon dioxide in copper concentrate was determined by alkali fused silica molybdenum blue spectrophotometric method. It was discussed about the solution conditions, absorption wavelength, solution acidity, water bath time, color and coexisting ions interference conditions on the influence of the absorbance. Sodium hydroxide as solvent,melting for 15 min at 680℃,melting sample effect was the best. The wavelength was selected according to the content of silicon dioxide in sample, detection wavelength was set of 810 nm for the silicon dioxide content of less than 1%, detection wavelength was set of 650 nm for the content of 1%–15%;the color effect was the best with hydrochloric acid solution of 0.15–0.20 mol/L, water bath heating of 60 s,color time of 15 min. Ammonium ferric sulfate was used as a reducing agent. The recoveries of standard addition was between 94.8%–98.8%, the relative standard deviations of five independent sample determination results were 0.26%–4.48%(n=11), the results in standard sample were consistent with the certified values. The method is simple, rapid, accurate and suitable for the determination of silicon dioxide content in the copper concentrate.