초록 ▼

An alkali hydroxide is added to an aqueous solution of ferrous salt to form a precipitate and a part of the solution is separated to control a ratio of an anion to a ferrous component to less than 1 and the ferrous component is oxidized to acicular goethite by bubbling air through the supernatant an

An alkali hydroxide is added to an aqueous solution of ferrous salt to form a precipitate and a part of the solution is separated to control a ratio of an anion to a ferrous component to less than 1 and the ferrous component is oxidized to acicular goethite by bubbling air through the supernatant and precipitate.

대표청구항 ▼

A process for producing an acicular goethite comprising: adjusting the pH of an aqueous solution of a ferrous salt to a value higher than 11; allowing a precipitate of ferrous hydroxide to form; adjusting the ratio of the anion of the ferrous salt to the ferrous hydroxide to 0.1 to 0.5 by separatin

A process for producing an acicular goethite comprising: adjusting the pH of an aqueous solution of a ferrous salt to a value higher than 11; allowing a precipitate of ferrous hydroxide to form; adjusting the ratio of the anion of the ferrous salt to the ferrous hydroxide to 0.1 to 0.5 by separating a portion of the supernatant from said precipitate; and oxidizing the precipitate by bubbling an oxygen-containing gas through the remaining supernatant and precipitate at a temperature lower than 80°C.