摘要:
采用湿法化学预氧化法结合高温熔融制样,波长色散-X射线荧光光谱法测定锌精矿中铜、硅、镁、锌、铝、铁、硫、铅、钙、砷、钾、镉、锰等主次量元素。通过对锌精矿样品的湿法化学预氧化处理(0.3 g样品+1 g硝酸锂+0.5 mL过氧化氢在铂金合金坩埚中混匀),能够增加样品的使用量,提高了熔片中待测微量元素的X射线荧光光谱强度。采用四硼酸锂熔剂高温熔融制样,降低了元素间的基体效应。针对硫化精矿的灼烧增量现象,提出了灼烧增量的计算方法及校正方法。对于无法使用灼烧增量进行校正的软件,提出将实际样品灼烧增量转换为虚拟样品灼烧失量的方法。用理论α系数和经验系数相结合的方法校正元素间的效应。测定锌精矿各组分(除镉以外)的相对标准偏差(RSD,n=12)均小于3%,方法检出限为6.55~111.24 μg/g,测定值与化学分析法结果吻合。
Abstract:
A method has been developed for the direct determination of Cu, Si, Mg, Zn, Al, Fe, S, Pb, Ca, As, K, Cd and Mn in zinc concentrate samples using a fusion method by Axios PW4400 XRF spectrometer. The conditions for pre-oxidation on sample preparation were studied using the wet chemical method. A 0.3 g sample with 1 g lithium nitrate and 0.5 mL liquid hydrogen (30%) were loaded into a platinum-gold crucible at room temperature. The sample and oxidants were mixed well by shaking the crucible. The higher sample/flux ratio increased the intensities of the trace elements signals in XRF. A lithium tetraborate fusion agent was applied to reduce the matrix effects among elements. The formula and calibration models of gain on ignition are discussed in this paper. The gain on ignition of the actual sample, which cannot be corrected by the software, was converted to the loss on ignition of a virtual sample. The matrix effects among different elements were corrected by theoretical alpha coefficients and empirical coefficients. The precision (RSD, n=12) of the method was less than 3% for all components except Cd. The detection limits of the method were 6.55-111.24 μg/g. Due to the analysis of CRM (GBW 07163 and GBW 07170 were mixed in a mass ratio of 1∶5) by this method, the obtained results are consistent with certified values.
下载: