A cone valve, which significantly reduces a risk of damaging a valve seat, even if it is used as a check valve when feeding slurry containing highly abrasive coarse particles such as slurry of nickel oxide ore. The cone valve of the present invention is a cone valve used as a check valve when feeding slurry, comprising: a valve seat; a valve body for performing opening and closing operation by reciprocally moving in predetermined directions with respect to the valve seat; and a coil spring incorporated to make the valve body contact the valve seat, wherein an annular abutting surface is provided in the valve seat by a contact with an end of the valve body, and the valve seat is configured to have a thickened part in which a thickness in normal direction of the abutting surface is increased inward from the abutting surface.

The present invention is to provide a process for removing magnesium contained as an impurity from nickel sulfate and producing high-purity nickel sulfate.

The process for producing an aqueous nickel sulfate solution from which magnesium is removed from nickel sulfate, comprises the following steps (1) to (3): (1) a carbonation step obtaining a slurry comprising nickel carbonate as a solid content by mixing a nickel sulfate aqueous solution and lithium carbonate, (2) a solid-liquid separation step of separating the slurry obtained in the carbonation step into a solid content and liquid component, and (3) a dissolution step dissolving the solid content obtained in said solid-liquid separation step with a solution containing sulfuric acid.

The present invention provides a method that is capable of selectively obtaining nickel and/or cobalt from an alloy, which contains copper. A method comprises: a leaching step S1 in which an alloy that contains copper as well as nickel and/or cobalt is subjected to a leaching treatment by means of an acid solution in the coexistence of a sulfurizing agent, thereby obtaining a leachate and a leaching residue; and a reduction step S2 in which a reducing agent is added to the thus-obtained leachate so as to reduce the leachate, thereby obtaining a post-reduction solution and a reduction residue. This method is characterized in that the reduction is carried out in the reduction step S2, while controlling the addition amount of the reducing agent so that the redox potential of the leachate is 0 mV or less as determined where a silver/silver chloride electrode is the reference electrode.

A system for using aqueous means for solubilizing chemical components contained in Sulphur type ore concentrate which may contain iron, cobalt, nickel, copper, platinum group metals and other metals considered valuable and of commercial interest, and a method of using the aqueous means for solubilizing such components is described.

Systems and methods for sequestering carbon, evolving hydrogen gas, producing iron oxide as magnetite, and producing magnesium carbonate as magnesite through sequential carbonation and serpentinization/hydration reactions involving processed olivineand/or pyroxene-rich ores, as typically found in mafic and ultramafic igneous rock. Precious or scarce metals, such nickel, cobalt, chromium, rare earth elements, and others, may be concentrated in the remaining ore to facilitate their recovery from any gangue material.

Provided is a method for smelting nickel oxide ore by which the occurrence of cracking due to heat shock can be suppressed when nickel oxide ore is pelletized and charged into a smelting step (reduction step). A method for smelting nickel oxide ore according to the present invention uses pellets of nickel oxide ore, the method being characterized by comprising a pellet production step S1 for producing pellets from nickel oxide ore, and a reduction step S2 for heating the resulting pellets at a predetermined reduction temperature in a reduction furnace, the reduction step S2 comprising preheating the pellets obtained in the pellet production step S1 to a temperature of 350 to 600 C. in the reduction furnace and thereafter charging the pellets into the reduction furnace and raising the temperature of the reduction furnace to the reduction temperature.

The present invention provides an aqueous cobalt chloride solution purification method, in which impurities can be efficiently removed from a cobalt salt solution.

Provided is a method for bringing metallic nickel into contact with an aqueous solution containing cobalt chloride to remove an impurity by a substitution reaction, in which the pH of the aqueous solution containing cobalt chloride is adjusted to not less than 1.5 and not more than 2.5. Since the pH of the aqueous solution containing cobalt chloride is adjusted to not less than 1.5 and not more than 2.5, a passive film on a surface of the metallic nickel can be effectively removed. When the passive film is removed, the metallic nickel comes in contact with the aqueous solution containing cobalt chloride, so that an impurity more noble than the metallic nickel can be precipitated by the substitution reaction. In addition, since the metallic nickel is only brought into contact with the aqueous solution containing cobalt chloride, the impurity can be easily removed from the aqueous solution containing cobalt chloride.

In an autoclave in a high pressure acid leaching process in which starting material slurry and sulfuric acid are stirred by stirring machines in each compartment in the autoclave partitioned by partition walls to proceed leaching, and slurry is transferred from a compartment on an upstream side to a compartment on a downstream side to sequentially proceed leaching, wherein starting material slurry supply tubes having the starting material slurry discharge ports and sulfuric acid supply tubes having sulfuric acid discharge ports are alternately disposed on a perimeter of stirring blades of the stirring machine provided in the compartment at an upstream end, and the starting material slurry and sulfuric acid are added to the compartment at the upstream end from the starting material slurry discharge ports and the sulfuric acid discharge ports positioned higher than an uppermost part of the stirring blades and lower than a contained liquid surface.

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.

A process for recovering non-ferrous metals from a solid matrix may include: leaching the solid matrix with an aqueous-based solution, in a presence of oxygen, to obtain an extraction solution including leached metals and solid leaching residue; separating the solid leaching residue from the extraction solution; and subjecting the extraction solution to at least one cementation to recover the leached metals in elemental state. The leaching solution may include chloride ions. The leaching solution may further include ammonium ions. A pH of the leaching solution may be greater than or equal to 6.5 and less than or equal to 8.5. A leaching temperature may be greater than or equal to 100 C. and less than or equal to 160 C. A leaching pressure may be greater than or equal to 150 kPa and less than or equal to 800 kPa.