热分解法制备磁铁粉的条件研究_化学系.doc

摘  要:磁铁粉是一种多功能磁性材料。本课题采用热分解法制备磁铁粉。研究了制备Fe(OH)3前驱体的不同制备方法与产品性状的关系，几种沉淀剂中以氨水沉淀制得的效果最好；研究了前驱体在木炭粉保护下在不同温度下焙烧，二价和三价铁的摩尔比，结果表明：650℃效果最佳；研究了焙烧时间对磁铁粉产品质量的影响，实验表明，2h为宜；研究了活性炭/铁比例与产品质量的关系。并研究了测定活性炭中二价铁和三价铁含量的方法，并用该方法检测试验期间的产品质量。本研究的工艺步骤是：使用氯化铁溶液，在室温下，用氨水为沉淀剂，控制PH为9，制得氢氧化铁前驱体，经干燥脱水，在木炭保护下，于650℃的马弗炉中灼烧2h。检测方法：盐酸溶样，重铬酸钾直接滴定测定二价铁，另外取样用锌粉还原铁后，再用重铬酸钾直接滴定测定总铁量，同时测定活性炭对三价铁的影响，扣除空白后，计算二价和三价铁的摩尔比。

关键词：氢氧化铁；热分解；四氧化三铁；磁性；活性炭

ABSTRACT:The magnet powder is a kind of multi-functional magnetic materials. The magnetic activated carbon was prepared by thermal decomposition in this paper. The relationship of several method for preparation of Fe(OH)3 precursor with products property was studied, and the best effect of preparation of product was the method of addition of ammonia. The mole ratio of Fe2+ and Fe3+ in the products prepared by thermal decomposition, with charcoal powder on the mixture of precursor/activated carbon to protect oxidation, was studied. It was show that a good temperature is at 650℃. The effect of heat time to product quantity show that suitable the time is 2 hours. A method of determination of the content of Fe2+ and Fe3+ in the products was studied, had been used during our experiment. The method express follow: at room temperature, addition of ammonia to FeCl3 solution(pH=9) formed the Fe(OH)3 precursor, moved to crucible by drying on electric furnace, then covers a layer of charcoal powder on its surface and using the porcelain sheet to separate them, reaction in furnace at 650℃ for 2 h. The detection the content of iron in sample: addition of HCl to dissolve sample and addition of water to 100 mL (sign as SS)，one of sample solution taken from SS used to detect Fe2+ with the potassium chromate method, another of sample solution taken from SS used to detect content of total iron, addition of Zn powder to reduce Fe3+ to Fe2+, with the potassium chromate method, same time，detection of blank value of the activated carbon, calculation of mole ratio of Fe3+ and Fe2+.

Keywords:  hydrogen ferric oxide; thermal decomposition; ferroferric oxide ; magnetic; activated carbon