矿石中金的快速测定——Z/8000原子吸收光谱法

RAPID DETERMINATION OF GOLD IN THE ORE BY THE Z/8000 ATOMIC ABSORPTION SPECTROPHOTOMETER METHOD

对于含硫化物样品,用2:1逆王水分解,泡沫塑料吸附,缩短(或省去)了除硫和有机碳的灼烧时间,解决了矿石中含硫和有机碳高时,经长时间灼烧,硫、碳仍除不尽,致使金的分析结果偏低的问题。逆王水分解后的试样用泡沫塑料分离富集金,回收率在95％以上。高含量金火焰法测定,低含量金石墨炉法测定,操作极为方便快速。火焰法测定时,特征浓度为0.48ppm/l％吸收,VC为2—11％;石墨炉法测定时,绝对灵敏度为2.48×10^(-11)g/l％吸收,VC为7.42％。

While determining gold by Z/8000 atomic absorption spectrophotometer, the enterance of -samples and data acquisition all controlled by computer. To deduct the backgrounds, Zeeman's effect is used and the Zeeman's flame-Zeeman's graphitic furnace atomizer switch is installed. Determination of gold of high content is carried out by flame method, while that of low conlent by graphitic fumace method. All the operations are extermely easy and rapid.In experiments samples are dissolved in 2:1 contrary aqua regin which saved the burnning time for exclusion of unnecessary sulphur and organic carbon. Thus, We have overcome the difficulty that the analytical results of gold are usurally underes timated, because a full exclusion of the sulphur and carbon is hardly achieved even after a long time of burnning, when the ore are bearing high content of sulphur and organic carbon. The recovery factor is more than 95% by using foamed plastics in the separation and enrichments. The preliminary treatment of samples are carried out by use of aqua regia, contrary aqua regia, NH4Cl, NH4Br as solvants. Comparative experiments have been made under different temperatures, burnning durations and by different method of burnning, and it has been found that feeding NH4Cl or NH4Br for exclusion of antinomy is not recommended, as during exclusion of stibium, AuCl3, AuBr3 suffer from volatilization loss in the burnning processes. When stibnite is solved in more concentrated HNO3, HSbO3 precipitates which prevents stibium from hydrolysing. Therefore, after stibnite and all the sulphureous ores are solved in 2:1 contrary aqua regin, the analytic results are raised by more thun 50%.The method has been proved to be reliable by more than one year practical examination. For determinations by flame method the test limit is 0.006 ppm (measured with 10 g of samples), the characterestic concentration is 0.48 ppm/1% absorption, the precision of the method based on the 11 determinations of 6.9 ppm of gold is as follows:RSD is 0.0211, VC is 2.11%. For determination by flameless method the test limit is 0.022 ppb (measured with 10 g of samples), the absolute sensitivity is 2.84×10-11 g/1%absorptions, based on the 11 determinations of 22.36 ppb of gold, RSD is 0.0742, VC is 7.42%.The present pater suggests a simple and rapid method for analysing gold in ore which has several advantages: easy operation, low cost, good selectivity, high precision and high sensitivity.