Mfr. of acicular goethite - by adding cobalt salt and alkali to ferrous salt to ppte. ferrous hydroxide and oxidising below 80 deg. c with sodium or potassium chlorate

摘要

Mfr. of acicular geothite, comprises adding cobalt salt and alkali to aq. ferrous salt soln.to adjust the soln. to above pH 11, alowing to ppte. ferrous hydroxide, adjusting proportion of anions to ferrous ions to below 1, adding sodium or potassium chlorate, and carrying out oxidn. at below 80 deg.C. The process makes possible to considerably shorten reaction time, and to obtain acicular goethite having a small particle size. In an example 167 g of FeSO4.7H2O and 0.84 g of CoSO4.7H2O, were dissolved in 1l water and furthermore 168 g of NaOH, added and water added in such a manner that total volume became 1.5l. The soln. was allowed to stand for 6h. to form ppte. of ferrous hydroxide. Afterwards, 750 mL of supernatant liq. of the soln. was removed, by which proportion of anions to ferrous ions was adjusted to below 1. Next, to this 12.3 g of potassium chlorate and 0.37g of sodium silicate soln., and water added in such a manner that total volume became 1.5l. The soln. was allowed to react at 50 deg.C for 8 h. The ppte. obtd. has the structure of acicular goethite.