实验用磁性铁分离装置的设计及其在铁矿石磁性铁测定中的应用

磁性铁含量的测定是铁矿勘查中的基本分析项目之一。以往常采用手工磁选法对磁性铁分离后再进行测定,但手工磁选法不仅容易出现清洗不彻底或由于水流难以控制使磁性铁流失等现象,而且各实验室采用的永久磁铁规格不统一也会导致测定结果的重现性较差。实验自主设计了由框架、传动及淋洗系统3大部分组成的磁性铁分离装置,不仅提高了分离效率,还可一人对多个样品同时操作。对该装置应用于磁性铁分离时的条件进行了单因素和正交试验,并将其应用于铁矿石中磁性铁含量的测定。结果表明,磁性铁分离装置对磁性铁分离的最佳条件是磁场强度为80Gs,水流速度为30mL/min,翻转速度为70r/min,淋洗时间为3min;样品中磁性铁的含量对测定结果的影响较小。采用实验方法对铁矿石物相成分分析标准物质中磁性铁含量进行测定,结果的相对标准偏差(RSD,n=8)为0.80%和1.0%。采用实验方法对2个铁矿石实际样品进行测定,测定结果与标准方法 YS/T 1047—2015基本吻合。

Design of magnetic iron separation apparatus for experiments and its application in the determination of magnetic iron in iron ore

The determination of magnetic iron content is one of basic analysis items in iron ore prospecting. In the past, the magnetic iron is usually separated by manual magnetic separation method followed by determination. However, this method has some disadvantages, for example, the cleaning is incomplete or the water velocity is hardly controlled to cause loss of magnetic iron. Moreover, the specification of permanent magnets used in different laboratories is not unified, which also cause the bad repeatability of determination results. The magnetic iron separation apparatus was self-designed in experiments, which was composed of three parts, i.e., frame, transmission and elution system. It not only improved the separation efficiency, but also realized the simultaneous operation of several samples by one person. The single factor and orthogonal experiments for magnetic iron separation conditions using this apparatus were investigated, and it was applied for the determination of magnetic iron content in iron ores. The results showed that the optimum conditions of this apparatus for the magnetic iron separation were as follows: the magnetic field intensity was 80Gs, the water velocity was 30mL/min, the overturn speed was 70r/min, and the elution time was 3min. The content of magnetic iron in sample had little influence on the determination results. The proposed method was applied for the determination of magnetic iron content in certified reference material for composition analysis of phases in iron ores. The relative standard deviations (RSD, n=8) of determination results were 0.80% and 1.0%. Two actual iron ore samples were determined according to the experimental method, and the found results were basically consistent with those obtained by standard method YS/T 1047-2015.