氟硅酸钾滴定法测定高碳铬铁中的硅

Determination of silicon in high carbon ferro-chrome by potassium fluosilicate titration

用KOH和KNO3混合熔剂在镍坩埚中熔融高碳铬铁,选取熔融温度为600℃,熔融时间为10min,减少了对镍坩埚的损害,易于浸取。采用自制的抽滤装置,将普通抽滤瓶进行改装,将玻璃砂芯漏斗部分用塑料代替,只需用四分之一张滤纸(滤纸直径约为40mm),抽滤速度快,滤纸不会穿漏,吸附的残余酸量很少,易于洗涤和中和,大大缩短了检测时间。方法用于高碳铬铁标准样品的测定,结果与国家标准方法——高氯酸脱水重量法测定结果相符,相对标准偏差小于5%。

High carbon ferro-chrome was melted with KOH and KNO3 in a nickel crucible.The melting temperature was selected at 600 ℃ and the melting time at 10 min so that the damage to nickel crucible was reduced for the convenience of leaching.A self-designed filtration device was made by refitting an ordinary filtration bottle through replacing glass-cored funnel with plastic materials,and only 1/4 filter paper（=40 mm） was needed.By this method,the filtration was rapid,the filtration paper remained complete,and the residual acid amount was small,which was easy to wash and neutralize,as a result,the detection time was greatly reduced.The proposed method has been applied to the determination of high carbon ferro-chrome,the result of which agreed well with the national standard-perchloric acid dehydration gravimetric method.The relative standard deviation was smaller than 5 %.