论文部分内容阅读
本法采用过氧化钠熔样,于pH5.5—6的缓冲溶液中,以一定量的Pb~(2+)沉淀钨使成钨酸铅,以二甲酚橙作指示剂,用EDTA标准溶液滴定过剩的Pb~(2+),换算出三氧化钨含量。分析手续:称取三氧化钨含量在65％以上的钨精矿试样1.0000克于50毫升铁坩埚中,加入8克过氧化钠,混匀,熔融。用约150毫升水(内含酒精5毫升)浸取。冷却,移入200毫升容量瓶,以水稀至刻度,摇匀。静置后,干滤,取滤液20毫升于
This method uses sodium peroxide melting sample, in a pH 5.5-6 buffer solution, a certain amount of Pb ~ (2 +) precipitated tungsten into lead tungstate, xylenol orange as an indicator, with EDTA standard Solution titration excess Pb ~ (2 +), conversion of tungsten trioxide content. Analysis procedures: Weigh tungsten oxide content of more than 65% tungsten trioxide samples 1.0000 grams in 50 ml iron crucible, add 8 grams of sodium peroxide, mixing, melting. Leach with about 150 ml of water (5 ml containing alcohol). Cooling, into 200 ml volumetric flask, diluted with water to the mark, shake. After standing, dry filtration, take the filtrate 20 ml at