The present disclosure provides a method for recovering nickel and cobalt, the method comprising: a first step of heat-treating lithium nickel cobalt aluminum oxide to produce a mixture; a second step of water-washing the mixture produced in the first step to obtain a residue; and a third step of heat-treating the residue obtained in the second step.

According to an embodiment, a method of forming a porous layer includes forming a porous layer containing a noble metal on a surface made of a semiconductor by displacement plating. The plating solution used in the displacement plating contains a noble metal source, hydrogen fluoride, and an adjusting agent adjusting a pH value or zeta potential. The noble metal source produces an ion containing the noble metal in water. The plating solution has a pH value in a range of 1 to 6.

Methods and reactor systems are provided for extracting metals, such as nickel, cobalt, and iron, from reduced, activated metal compounds (feed materials). Feed materials may be derived from mixed hydroxide precipitate. Feed materials and carbon monoxide gas are delivered into an extraction reactor of a reactor system, such as a shell tube heat exchanger. A flow path therein directs the feed material downward and the carbon monoxide gas upward, enabling contact therebetween, forming at least one metal carbonyl gas and a solid residue therein. The flow path further directs the upward flow of metal carbonyl gases, and the downward flow of the residue. Methods and reactor systems may further purge the residue: using nitric oxide to convert any remaining dicobalt octacarbonyl therein to cobalt tricarbonyl nitrosyl gas; using an inert gas to removing any cobalt tricarbonyl nitrosyl therein; and using an inert gas-oxygen mixture, to form a passivated residue.

Methods and reactor systems are provided for extracting metals, such as nickel, cobalt, and iron, from reduced, activated metal compounds (feed materials). Feed materials may be derived from mixed hydroxide precipitate. Feed materials and carbon monoxide gas are delivered into an extraction reactor of a reactor system, such as a shell tube heat exchanger. A flow path therein directs the feed material downward and the carbon monoxide gas upward, enabling contact therebetween, forming at least one metal carbonyl gas and a solid residue therein. The flow path further directs the upward flow of metal carbonyl gases, and the downward flow of the residue. Methods and reactor systems may further purge the residue: using nitric oxide to convert any remaining dicobalt octacarbonyl therein to cobalt tricarbonyl nitrosyl gas; using an inert gas to removing any cobalt tricarbonyl nitrosyl therein; and using an inert gas-oxygen mixture, to form a passivated residue.