四硼酸锂-偏硼酸锂熔融-重铬酸钾滴定法测定铁矿石中全铁  

Determination of total iron in iron ore by potassium dichromate titration with lithium tetraborate-lithium metaborate fusion

作　　者：滕广清 张改梅 鲍希波 TENG Guangqing;ZHANG Gaimei;BAO Xibo(Technique Center,Handan Iron and Steel Company,Hebei Iron and Steel Group,Handan 056015,China)

机构地区：[1]河钢集团邯钢公司技术中心,河北邯郸056015

出　　处：《冶金分析》2023年第9期76-80,共5页Metallurgical Analysis

摘　　要：铁矿石是冶金行业的重要原料之一,全铁是最重要的计价元素,因此测定铁矿石中全铁含量至关重要。标准方法GB/T 6730.65—2009采用碳酸钠-硼酸熔融法处理样品时,不仅需要用大量酸浸取熔融物,且操作较为繁琐。本文提出用四硼酸锂-偏硼酸锂熔融法处理样品,通过加入脱模剂使熔融物自动剥离,仅需少量酸即可将熔融物完全溶解,不仅简化了操作,而且节约了试剂。对熔样条件进行了优化,通过控制熔剂与样品的质量比为5∶1,将样品置于盛有四硼酸锂-偏硼酸锂混合熔剂的铂金坩埚中,混匀,加入0.5mL 300g/L碘化铵溶液作为脱模剂,将铂金坩埚置于1000℃的高温炉中熔融10min;冷却后熔融物自动剥离,将熔融物置于盐酸(1+10)中进行溶解,向试液中滴加氯化亚锡溶液将三价铁还原二价铁后,以二苯胺磺酸钠为指示剂,建立了重铬酸钾滴定法测定全品类铁矿石中全铁含量的方法。选用磁铁矿和烧结矿标准样品,按照实验方法测定,测定结果的相对标准偏差(RSD,n=9)均小于0.3%。分别采用实验方法和标准方法GB/T 6730.65—2009中碳酸钠-硼酸熔融-重铬酸钾滴定法对铁矿石标准样品中全铁进行测定,两种方法测定结果基本一致,且两种方法测定值与认定值/标准值的误差均在标准方法GB/T 6730.65—2009允许差范围内。Iron ore is one of the important raw materials in the metallurgical industry,and total iron is the most important pricing element.Therefore,it is of great significance to determine total iron content in iron ore.When the sample is treated with Na_(2)CO_(3)-H_(3)BO_(3)fusion according to the standard method of GB/T 6730.65-2009,a large amount of acid is required to leach the melt,and the operation is relatively tedious.The sample was treated with Li_(2)B_(4)O_(7)-LiBO2fusion,and the melt could be peeled automatically by adding release agent.Only a small amount of acid was required to completely dissolve the melt,which not only simplified the operation,but also saved the reagents.The sample fusion conditions were optimized.The mass ratio of flux to sample was 5∶1.The sample was placed in a platinum crucible containing the mixed flux of Li_(2)B_(4)O_(7)-LiBO_(2).After mixing,0.5mL of 300g/L NH4I solution was added as the release agent.The platinum crucible was heated in high-temperature furnace at 1000℃for 10min.After cooling,the melt was peeled automatically and then dissolved with HCl(1+10)solution.The SnCl_(2)solution was dripped to reduce Fe(Ⅲ)to Fe(Ⅱ).Consequently,a determination method of total iron content in all kinds of iron ores was established by potassium dichromate titration with sodium diphenylamine sulfonate as the indicator.The certified reference materials of magnetite and sinter were determined according to the proposed method.The relative standard deviations(RSD,n=9)of the determination results were all less than 0.3%.The contents of total ion in certified reference materials of iron ore were determined according to the proposed method and potassium dichromate titration with Na_(2)CO_(3)-H_(3)BO_(3)fusion in the standard method of GB/T 6730.65-2009.The determination results of two methods were basically consistent.Moreover,the errors between the determination results by the above two methods and the certified values or reference values were both within the allowable range specified in the

关 键 词：四硼酸锂 偏硼酸锂 重铬酸钾滴定法 铁矿石 全铁 磁铁矿 烧结矿 

分 类 号：O655.23[理学—分析化学] TF031[理学—化学]