Abstract: This paper studied the influence on elimination of calcium and magnesium by NH4F during the preparation of Mn-Zn ferrite precursor by coprecipitation.The results of experiments showed that the quantity of NH4F,time and temperature of reaction and pH were of obvious influence on elimination of calcium and magnesium.Under the best conditions——the volume fraction of 370.4　g·L^-1 NH4F was 2.4×10^-2,temperature was 90　℃ and the reaction time was 1 h and pH was 3.5,the contents of calcium and magnesium in purified solution were 0.003 and 0.019 g·L^-1 respectively, while the contents of calcium and magnesium in the precursor were 7.5×10^-5 and 5.6×10-5,less than 10^-4,so the precursor of Mn-Zn ferrite by coprecipitation was fit to be used to prepare high-quality product.

Key words: Mn-Zn ferrite precursor, co-precipitation, elimination of calcium and magnesium