| 摘要 |
<p>Iron-contg. permanently magnetisable material is prepared by forming a soln. contg. a compd. of iron and optionally one or more other metals, whose irons are present in the divalent state in the soln. and suspended support material, precipitating the iron oxide onto the suspended support material by gradually and homogeneously converting the divalent iron ions into the trivalent state by gradually injecting into the suspension a soln. of a rapidly acting oxidising agent, such as potassium permanganate or sodium nitrite, with agitation at pH 2-6.5 under controlled temp. conditions, separating the loaded support material from the liquid, washing, drying and subjecting to thermal treatment.</p> |
