火试金重量法测定载金炭中银

Determination of silver in gold-loaded carbon by fire assay gravimetric method

称取一定量的载金炭进行火试金配料,经过熔炼、灰吹得到金银合粒,使用硝酸分金得到金粒,再通过计算得到载金炭中银含量,从而建立了火试金重量法测定载金炭中银含量的方法。经过试验,确定了火试金配料中试样量、氧化铅加入量、灰吹温度等最佳试验条件。根据目前国内载金炭的生产水平,在载金炭国家标准物质加入一定量的共存元素,进行了银量测定的干扰试验,结果表明载金炭中共存元素(Cu、Fe、Pb、Cd、Zn、Bi、Cr、Ca、Mg、As)对银测定无影响。将方法用于3个载金炭国家标准物质中银的测定,测定值与认定值基本吻合,相对标准偏差(RSD,n=11)为0.82%~4.2%。

Certain amount of gold-loaded carbon was sampled for fire assay tests.The gold-silver composite particles were obtained after smelting and cupellation.The gold particles were then obtained by decomposition with nitric acid.Thus the content of silver in gold-loaded carbon could be calculated.The determination method of silver in gold-loaded carbon by fire assay gravimetry was established.The optimum experimental conditions were investigated,including the sample amount in fire assay,the dosage of lead oxide and the cupellation temperature.According to the current situation of domestic gold-loaded carbon production,some coexisting elements were added into certified reference materials of gold-loaded carbon for the interference tests.The results showed that the coexisting elements（Cu,Fe,Pb,Cd,Zn,Bi,Cr,Ca,Mg and As）in gold-loaded carbon had no influence on the determination of silver.The proposed method was applied to the determination of silver in three certified reference materials of gold-loaded carbon.The found results were basically consistent with the certified values.The relative standard deviations（RSD,n=11）were between 0.82% and 4.2%.