PURPOSE: To obtain goethite having a sharp particle size distribution with little branching in a process for oxidizing an aqueous solution of a ferrous salt with an alkali agent, by forming crystal nuclei of the geothite on the alkaline side, and growing the resultant crystal nuclei on the acidic side.
CONSTITUTION: An aqueous solution of one or more alkali agents, e.g. hydroxides or carbonates of an alkali metal, in an equivalent amount or more based on a ferrous salt is added to an aqueous solution of the ferrous salt and uniformly mixed. An oxidizing agent, e.g. air is then fed thereto to deposit crystal nuclei of α-FeOOH on the alkaline side. A fresh aqueous solution of the ferrous salt is further added to the alkaline suspension to keep the suspension temperature at 30W80°C. The alkali agent is then added to oxidize the ferrous salt while keeping the pH at 7W2.5 to grow the above-mentioned crystal nuclei of the α- FeOOH. The aimed needle-like goethite suitable to a raw material for iron oxide used in magnetic recording or metallic powder is obtained by the method.
SAKAMOTO YASUKIYO
ORIHARA YOSHITAKA
OCHIAI HIROSHI
| JPS58192308A | 1983-11-09 |