Sumitomo Metal Mining Company, Ltd.

Naoko Kikuta

Satoshi Asano

Masatoshi Takano

Takao Suzuki

Ryozo Ushio

Iichi Nakamura

Ryoichi Nakayama

Yuji Imaizumi

Masayuki Hisatsune

Koji Sasaki

The method for obtaining an acid solution containing nickel is obtained by treating a positive electrode material of a nickel-metal hydride battery. The method includes a water-washing step, wherein a positive electrode material of a nickel-metal hydride battery is water-washed by adding water, and then separated to form a positive electrode material after water-washing and a water-washed slurry. An acid-washing step then is performed, wherein an acid is added and mixed into the positive electrode material obtained after water-washing in the water-washing step, and, separation is performed to form a positive electrode material after acid-washing and an acid-washed slurry. A dissolution step is performed wherein the positive electrode material obtained in the acid-washing step is separated into a nickel solution and a dissolution residue by adding any one of an acid and an oxidizing agent.

Method for producing nickel-containing acid solution

A method for separating nickel, cobalt and a rare earth element from a material containing positive and negative electrode active materials of a nickel-metal hydride battery includes mixing a material containing positive and negative electrode active materials with a sulfuric acid solution and dissolving therein, and then separating a leachate from a residue; adding an alkali metal sulfate to the leachate to obtain a mixed precipitate of double sulfate of rare earth elements, and a rare-earth-element-free solution; and adding a sulfurizing agent to the rare-earth-element-free solution to separate a nickel and cobalt sulfide raw material and a residual solution.

Method for separating nickel and cobalt from active material contained in spent nickel-metal hydride battery

A method is provided for decomposing free cyanide ion and metallic cyano complex ions in a liquid, comprising the steps of bringing the liquid into contact with ozone gas in a counterflow relation in the condition that the pH of the liquid is at least 10 with the mass flow rate of the ozone in the ozone gas up to 20 mg per minute per liter of liquid, and then bringing the liquid into contact in a counterflow relation with ozone gas having an ozone concentration of at least 150 g/m,in the condition that the pH of the liquid is 7.0 to 9.5.

Method of processing cyanide ions by ozone

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Ehime, Japan

Naoko Kikuta