微波消解-丁二酮肟沉淀分离-EDTA返滴定法测定含镍生铁中镍

含镍生铁是不锈钢冶炼重要原材料,准确快速检测含镍生铁中镍含量对不锈钢冶炼质量控制及成本控制至关重要,而使用丁二酮肟重量法测定含镍生铁中镍需使用大量酸溶解样品,有时还需要对不溶性残渣进行熔融处理,过程繁琐。实验利用微波消解法处理含镍生铁样品,并通过丁二酮肟沉淀分离法使含镍生铁中镍与钴、铜有效分离,再使用EDTA返滴定法测定镍,最终建立了含镍生铁中镍含量的测定方法。使用5个含镍生铁标准样品进行验证,当镍质量分数为5%～20% 时,测定结果的相对标准偏差(RSD,n=7)为0.14%～0.33%;通过t检验法进行显著性检验,测定结果与标准值之间无显著性差异。分别按照实验方法和国标方法GB/T 31924—2015《含镍生铁 镍含量的测定 丁二酮肟重量法》对同一个含镍生铁样品进行检验,使用t检验对两种方法得到的结果进行统计分析,结果表明两种方法检验结果无显著性差异。

Determination of nickel in nickel pig iron by microwave digestion- dimethylglyoxime precipitation separation-EDTA back titration

Nickel pig iron is an important raw material for stainless steel smelting.The accurate and rapid detection of nickel content in nickel pig iron is very important for the quality and cost control of stainless-steel melting. During the determination of nickel in nickel pig iron by dimethylglyoxime gravimetric method, a large amount of acid is required to dissolve the sample. Sometimes the insoluble residue should be treated by fusion with complicated procedures. The nickel pig iron sample was decomposed by microwave digestion. Nickel was effectively separated with cobalt and copper by dimethylglyoxime precipitation separation. Then the content of nickel was determined by EDTA back titration. Consequently, a method for the determination of nickel in nickel pig iron was finally established. Five certified reference materials of nickel-containing pig iron were used for verification.The relative standard deviations (RSD, n=7) of the measurement results were between 0.14% and 0.33% when the mass fraction of nickel was 5%-20%. The significance test was carried out by the t test. The results showed that there was no significant difference between the standard and measured values. Same nickel pig iron sample was determined according to the experimental method and national standard method GB/T 31924-2015 Nickel pig iron-Determination of nickel content-dimethylglyoxime gravimetric method, respectively. The results indicated that there was no significant difference between two methods.