镍锍试金-电感耦合等离子体质谱法测定铜精矿中6种铂族元素的含量

Determination of 6 Platinum Group Elements in Copper Concentrate by Inductively Coupled Plasma Mass Spectrometry with Nickel Sulphide Fire Assay

针对目前火试金-电感耦合等离子体质谱法(ICP-MS)测定铜精矿中元素时存在扣渣分离操作复杂、难以满足生产需求的问题,优化了试金配料,进行了题示研究。取样品5 g及30 g硼砂、15 g碳酸钠、1 g升华硫、10 g二氧化硅、3 g硝酸钠、10 g氟化钙、4 g羰基铁粉、1.5 g羰基镍粉,混匀,置于黏土坩埚中,加入质量比3∶1的轻质氧化镁-碳化硅混合物至物料被完全覆盖,于1050℃保温15 min。冷却后取出锍扣,放入100 mL磨口三角瓶中,加入30 mL水,待锍扣分散后加入30 mL盐酸,于160℃溶解至溶液清澈且无气泡冒出。冷却后用0.45μm混合纤维素滤膜过滤,用10%(体积分数)盐酸溶液洗涤。将沉淀物转移到磨口三角瓶中,加入5 mL王水(体积比3∶1的盐酸-硝酸混合液),于120℃溶解至溶液清澈,用水定容至25 mL,采用ICP-MS碰撞池模式测定钌、铑、钯、锇、铱、铂等6种铂族元素含量。结果表明,试金配料中硝酸钠降低了样品中过剩的还原力,避免贱金属进入锍扣,以便获得质量合适的锍扣;氟化钙改善了熔渣流动性,使锍扣更易沉降;质量比3∶1的轻质氧化镁-碳化硅混合物作为覆盖剂能更有效地减少熔融过程中锇、钌的损失。各元素的质量浓度均在100.0μg·L^(-1)以内与所对应的响应强度和内标(镥)响应强度比呈线性关系,检出限(3s)为0.017~0.139μg·kg^(-1);方法用于国家标准物质的分析,其测定值的相对标准偏差(n=12)均小于8.0%;对空白样品进行加标回收试验,回收率为90.0%~109%。

In response to the current problem of complex slag separation operation and difficulty in meeting production requirements in the determination of elements in copper concentrates by inductively coupled plasma mass spectrometry(ICP-MS)with fire assay,the assay ingredients had been optimized and a research mentioned by the title was conducted.5 g of the sample was taken,mixed with 30 g of borax,15 g of sodium carbonate,1 g of sublimated sulfur,10 g of silica,3 g of sodium nitrate,10 g of calcium fluoride,4 g of carbonyl iron powder,and 1.5 g of carbonyl nickel powder.The mixture was placed in a clay crucible,and covered with a mixture of lightweight magnesium oxide-silicon carbide at a mass ratio of 3∶1,keeping at 1050℃for 15 min.After cooling,the matte buckle was taken and placed in a 100 mL-ground triangular flask.30 mL of water was added,and 30 mL of hydrochloric acid was added after the matte buckle was dispersed.The mixture was dissolved at 160℃until the solution was clear and no bubbles emerged.After cooling,the mixture was filtered with a 0.45μm mixed cellulose filter membrane and washed with 10%(volume fraction)hydrochloric acid solution.The sediment was transfered into a ground triangular flask,and 5 mL of aqua regia(a mixture of hydrochloric acid and nitric acid at a volume ratio of 3∶1)was added.The sediment was dissolved at 120℃until the solution was clear and made its volume up to 25 mL with water.6 platinum group elements were determined by ICP-MS in collision pool mode.As shown by the results,sodium nitrate in the assay ingredients reduced the excess reducing power in the sample,and avoided the entry of base metals into the sulforaphane,in order to obtain a suitable quality matte buckle.Calcium fluoride improved the fluidity of slag,and was easier for the slag to settle.A mixture of lightweight magnesium oxide-silicon carbide at a mass ratio of 3∶1 as the covering agent could effectively reduce the loss of osmium and ruthenium during the melting process.Linear relationships between the corresponding response intensity and the internal standard(lutetium)response intensity ratios and mass concentrations of elements were found within 100.0μg·L^(-1),with detection limits(3s)of 0.017-0.139μg·kg^(-1).This method was used for the analysis of national standard substances,with RSDs(n=12)of the determined values less than 8.0%.Test for recovery was made on the blank sample by standard addition method,giving results in the range of 90.0%-109%.