Abstract: Provided is a method for manufacturing a nickel and cobalt mixed sulfide that is capable of stabilizing nickel and cobalt concentrations in the sulfidation end solution at low levels and of limiting decreases in nickel and cobalt recovery rates without increasing cost even when processing with a sulfuric acid acidic solution containing nickel and cobalt and a high iron ions concentration as the sulfidation start solution. This method generates a sulfidation reaction by blowing hydrogen sulfide gas into a sulfuric acid acidic solution comprising nickel and cobalt to obtain a mixed sulfide, wherein: the sulfuric acid acidic solution, which is the sulfidation start solution, contains iron ions at a rate of 1.0-4.0 g/L; and the sulfidation reaction is generated by blowing hydrogen sulfide gas into the sulfidation start solution and adding sodium hydrogensulfide (NaHS) obtained by absorbing hydrogen sulfide gas-containing exhaust gas, generated by the sulfidation, in an alkaline solution.

Abstract: Provided is a method for manufacturing a nickel and cobalt mixed sulfide that is capable of stabilizing nickel and cobalt concentrations in the sulfidation end solution at low levels and of limiting decreases in nickel and cobalt recovery rates without increasing cost even when processing with a sulfuric acid acidic solution containing nickel and cobalt and a high iron ions concentration as the sulfidation start solution. This method generates a sulfidation reaction by blowing hydrogen sulfide gas into a sulfuric acid acidic solution comprising nickel and cobalt to obtain a mixed sulfide, wherein: the sulfuric acid acidic solution, which is the sulfidation start solution, contains iron ions at a rate of 1.0-4.0 g/L; and the sulfidation reaction is generated by blowing hydrogen sulfide gas into the sulfidation start solution and adding sodium hydrogensulfide (NaHS) obtained by absorbing hydrogen sulfide gas-containing exhaust gas, generated by the sulfidation, in an alkaline solution.

Abstract: Provided is a production method for refining iron oxide (hematite), which has such a low sulfur content as to be used as an iron-making raw material, from a leach residue containing iron oxide produced by a high pressure acid leach (HPAL) process. In the method for refining iron oxide for ironmaking by a process of adding sulfuric acid to nickel oxide ore and then leaching nickel from the nickel oxide ore using a pressure vessel, an amount of the sulfuric acid added is 150 kg or more and 220 kg or less per ton of nickel oxide ore.

Abstract: Provided is a method for producing hematite for ironmaking, wherein high purity hematite, which can be used as an iron-making raw material, is cheaply and efficiently recovered from a leach residue containing iron oxide produced by a high pressure acid leach (HPAL) process. This method for producing (high purity) hematite for ironmaking in a process of adding a mineral acid and an oxidant to ore containing iron and valuable metals and then leaching the valuable metals under high pressure and high temperature includes (1) a neutralization step of adding a neutralizer to a leachate obtained under high pressure and high temperature to form a leach slurry, (2) a solid-liquid separation step of separating the leach slurry obtained in the neutralization step (1) into a leach residue and the leachate, and (3) a classification step of classifying the leach residue into the hematite and gangue components.

Abstract: An object of the present invention is to provide a settling separation process for a neutralized slurry in which a neutralization step is efficiently performed for a leachate obtained by the leaching of nickel and cobalt from a nickel oxide ore, and further a neutralized precipitate obtained by precipitation of impurity components can effectively be separated and removed while inhibiting the filtration failure; and to provide a hydrometallurgical process for a nickel oxide ore, in which the above process is applied. In the present invention, a neutralization step is performed by using a magnesium oxide for a leachate obtained by the leaching of nickel and cobalt from a nickel oxide ore to obtain a neutralized slurry, and a neutralized precipitate is separated and removed by the addition of a cationic flocculant into the neutralized slurry.

Abstract: Provided is a production method for refining iron oxide (hematite), which has such a low sulfur content as to be used as an iron-making raw material, from a leach residue containing iron oxide produced by a high pressure acid leach (HPAL) process. In the method for refining iron oxide for ironmaking by a process of adding sulfuric acid to nickel oxide ore and then leaching nickel from the nickel oxide ore using a pressure vessel, an amount of the sulfuric acid added is 150 kg or more and 220 kg or less per ton of nickel oxide ore.

Abstract: Provided is a method for producing hematite for ironmaking, wherein high purity hematite, which can be used as an iron-making raw material, is cheaply and efficiently recovered from a leach residue containing iron oxide produced by a high pressure acid leach (HPAL) process. This method for producing (high purity) hematite for ironmaking in a process of adding a mineral acid and an oxidant to ore containing iron and valuable metals and then leaching the valuable metals under high pressure and high temperature includes (1) a neutralization step of adding a neutralizer to a leachate obtained under high pressure and high temperature to form a leach slurry, (2) a solid-liquid separation step of separating the leach slurry obtained in the neutralization step (1) into a leach residue and the leachate, and (3) a classification step of classifying the leach residue into the hematite and gangue components.