样品制备对褐铁矿总铁含量测定结果的影响

Effect of sample preparation on determination results of total iron content in limonite

采用化学分析法对不同研磨时间的褐铁矿样品进行了总铁含量测定，同时采用热失重分析和X射线衍射分析方法对不同研磨时间得到不同粒度分布的褐铁矿样品进行了分析。结果表明：研磨2min时总铁含量为57．87％，进一步间歇式研磨3～12min总铁含量从58．00％提高到58．43％，即褐铁矿样品研磨时间越长，样品温度升的越高，样品中的化合水失去的越多，导致样品中总铁含量相对提高。所以规定当制备褐铁矿样品时，应采用研磨过程不产生过多热量而明显改变其化学成分的工艺，即研磨样品至-160μm为宜，不需研磨至-100／2m，更不宜1次性连续研磨至～100μm。

The content of total iron in limonite sample was determined by chemical analysis under different sample grinding time. The samples with different grain size distribution after different grinding time were analyzed by thermogravimetic analysis and X-ray diffraction analysis to observe the heat weight loss and component change of sample. The results indicated that the total iron content was 57.87 % when the grinding time was 2 rain. The total iron content could increase from 58. 00 % to 58. 43% after further intermittent grinding for 3-12 min. In other words, the longer the grinding time of limonite sample was, the higher the sample temperature became, and the more the hydration water in sample lost, resulting in the improvement of total iron content. Therefore, during the preparation of limonite samples, excessive heat could not be generated to avoid the change of chemical composition. The appropriate size of samples was -160μm （unnecessary to -100μm）. The samples should not be continuously grinded to -100μm once.