自动电位滴定法测定冶金辅料中氧化钙和氧化镁

利用自动电位滴定仪, 测定了冶金辅助材料中氧化钙和氧化镁的含量。考察了滴定参数的影响, 最终确定滴定波长为660 nm, 搅拌速度为1 250 r/min, 预搅拌时间为30 s, 每次加入滴定剂后, 仪器达到的电位差dE(set)为8 mV;平衡条件(dE/dt)设置为0.5 mV, 等待的最长时间间隔t(max)为15 s;测定氧化钙时, 设置阈值为100 mV/mL, 测定氧化钙、氧化镁合量时, 设定阈值为300 mV/mL。将方法应用于白云石标准样品、石灰石标准样品、炉渣标准样品耐火材料标准样品中氧化钙和氧化镁的测定, 结果与认定值一致, 相对标准偏差(RSD, n=7)为0.06%~0.77%, 加标回收率为99%~101%。

Determination of calcium oxide and magnesium oxide in metallurgical auxiliary materials by automatic potentiometric titration

A new method was established for the determination of calcium oxide and magnesium oxide in metallurgical auxiliary materials based on automatic potentiometric titration instrument.The impact of titration parameters was studied and the final testing conditions were established as follows: titration wavelength of 660 nm, mixing speed of 1 250 r/min and premixing time of 30 s, and the potential difference of 8 mV after the addition of titrant, balancing condition (dE/dt) of 0.5 mV and the longest interval t (max) of 15 s. The threshold value was set as 100 mV/mL, 300 mV/mL respectively while determination of calcium oxide and the combination of calcium oxide and magnesium oxide. The method was applied for the determination of calcium oxide and magnesium oxide in the certified reference materials of dolomite, limestone, slag and refractories. The results were consistent with certified values, and the relative standard deviations (RSD, n=7) were 0.06%-0.77% with recoveries of 99%-101%.