碱熔融沉淀分离-EDTA滴定法测定铜精矿中三氧化二铝

建立了碱熔融沉淀分离- EDTA滴定法测定铜精矿中三氧化二铝的方法。样品用氢氧化钠和过氧化钠熔融，经沉淀分离除去大部分干扰元素。在一定酸度下，用过量的EDTA溶液完全络合铝、锌、锡等离子后，加入焦性没食子酸消除锡的干扰。以氟盐取代Al-EDTA，用醋酸锌标准溶液滴定游离的EDTA，根据消耗的醋酸锌标准溶液的体积计算三氧化二铝的含量。详细研究了熔剂的选择及其加入量、熔融时间、浸出用水量、缓冲溶液加入量、沉淀吸附离子效应、杂质干扰等因素对测定结果的影响，并确定了最佳测定条件。该方法应用于实际样品的分析，相对标准偏差为0.37%～0.85%,加标回收率介于98.8%～99.0%之间。

Determination of aluminum oxide in copper concentrates by base melting and precipitation separation-EDTA titration

A basic melting and precipitation separation-EDTA titration method for the determination of aluminum oxide in copper concentrates was established.The samples were melted by sodium hydroxide and sodium peroxide,and most of the interfering elements were separated through precipitation.At certain pH,the elements including aluminum,zinc and tin ions reacted with excessive EDTA,and then pyrogallic acid was added to eliminate the interference of tin.By replacing Al-EDTA with fluoride salt,the obtained free EDTA were titrated with standard solution Zn(Ac)2.The content of aluminum oxide was thus calculated according to the consumption of standard solution Zn(Ac)2.The influencing factors were investigated,including selection and dosage of fluxes,melting time,water amount for leaching,dosage of buffer solution,precipitates absorption effect and impurities interferences.The optimal determination conditions were finally obtained.The method was applied to the analysis of sample,and it was found that the relative standard deviation(RSD) was in the range of 0.37%-0.85 % and the standard addition recovery was between 98.8%-99.0%.