Nisshin Steel Co., Ltd.

Akihiro Asaba

Masaya Yamamoto

Yasushi Fukui

Shoichi Matsuo

The purpose of the present invention is to provide a method for recovering calcium-containing solid components from steelmaking slag, with which it is possible to easily increase the calcium recovery rate. With the method, steelmaking slag is immersed in an aqueous solution containing carbon dioxide, and calcium in the steelmaking slag is made to leach out into the aqueous solution. Next, the immersed steelmaking slag is removed from the aqueous solution, and, subsequently, the pH of the aqueous solution is increased. When solid components precipitated by doing so are recovered, it is possible to recover solid components containing 20% or more by mass in terms of calcium atoms.

Method for recovering calcium-containing solid component from steelmaking slag and recovered solid component

An aqueous solution containing 30 ppm or more of carbon dioxide is brought into contact with a steel-making slag to elute phosphorus and calcium contained in the steel-making slag into the aqueous solution. Subsequently, carbon dioxide is removed from the aqueous solution to precipitate a mixture comprising a phosphorus compound and a calcium compound. In this manner, a mixture comprising a phosphorus compound and a calcium compound and containing phosphorus in an amount of 1% by mass or more in terms of phosphorus atom content can be produced.

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Osaka, Japan

Akihiro Asaba