氯化铵-氨水分离碘量法检测铜矿石中铜含量的测量不确定度评定

Evaluation of Measurement Uncertainty of Copper Content in Copper Ore by Ammonium Chloride and Ammonia Water Separation Iodine Method

依据氯化铵-氨水分离碘量法测定铜矿石中的铜含量,利用日常检测结果,以极差估计标准偏差,通过柯克伦检验,日常的铜检测精度没有显著性差异,回归分析表明标准偏差和铜含量之间没有显著性的相关关系,以合并样本标准偏差作为A类不确定度。B类不确定度的来源主要涉及天平、滴定管、滴定度等误差,逐一进行了量化并通过数学模型进行合成,从而计算合成不确定度和扩展不确定度。最终得到铜测量值在6.81%至12.50%之间,单次检测的A类不确定度为0.05%。对一个样品的两次检测平均值为w(铜)7.35%,包含概率95%,U=0.10%。在评定过程发现,A类标准不确定度略大于B类标准不确定度,B类标准不确定度分量中滴定度、试样质量的贡献较大。提高铜含量测量准确性的有效措施为:提高金属铜称样量、样品试样称样量及分取铜标准溶液体积。

The copper content in copper ore is determined by ammonium chloride and ammonia water separation iodine method.Using the daily test results,estimate the standard deviation by the range method.Through the Cochrane test,there is no significant difference in the daily detection accuracy of copper.Regression analysis shows that there is no significant correlation between the standard deviation and the copper content.The pooled sample standard deviation is taken as the type A uncertainty.The sources of type B uncertainty mainly involve balance,burette,titre and other errors,which are quantified one by one and combined through mathematical models.The combined uncertainty and expanded uncertainty are then calculated.Finally,the measured value of copper is between 6.81%and 12.50%,and the type A uncertainty of a single test is 0.05%.For a sample,the average value of copper detected twice is 7.35%,with U=0.10%under coverage probability is 95%.In the evaluation process,it is found that type A uncertainty is slightly greater than type B uncertainty,and titre and sample quality contribute more to type B uncertainty.The effective improvement measures to improve the copper content are to increase the weighing sample amount of metal copper,increase the volume of copper standard solution,and increase the weighing of samples.