JP2019116656A - Method for producing nickel powder - Google Patents

Abstract

To provide a method for producing nickel powder where, when a hydrogen gas is blown into a nickel sulfate ammine complex water solution stored in a high temperature-high pressure container in a high temperature-high pressure state, nickel ions and the hydrogen gas in the water solution are efficiently reacted to stably obtain nickel powder with a uniform size.SOLUTION: Provided is a method for producing nickel powder characterized in that, in a method where a nickel sulfate ammine complex solution and a hydrogen gas are reacted in a high temperature-high pressure container, and nickel ions in the complex solution are reduced with the hydrogen gas to obtain the powder of nickel, where, after a two phase state of a liquid phase part-a vapor phase part with the complex solution as the liquid phase is formed in the high temperature-high pressure container, a hydrogen gas is blown into the vapor phase part, and is sprayed on the solution face of the nickel sulfate ammine complex solution, and the vapor phase composed of the hydrogen gas and the liquid phase composed of the complex solution are contacted at a boundary formed by the vapor phase and the liquid phase, thus the nickel ions in the nickel ammine complex are subjected to reduction treatment with the hydrogen gas to generate nickel powder.SELECTED DRAWING: None

Description

  The present invention relates to a method of reducing nickel ions in a nickel sulfate ammonium complex solution with hydrogen gas to obtain a nickel powder.

As one of the methods for industrially producing nickel powder using a hydrometallurgical process, as shown in Patent Document 1, a nickel oxide ore, a nickel-containing raw material such as scrap or an intermediate raw material, and a sulfuric acid solution are used. A sulfuric acid solution containing nickel obtained by contacting is subjected to a method such as neutralization treatment or solvent extraction to remove coexisting impurities, and then ammonia is added to the sulfuric acid solution from which the impurities have been removed. Complexing nickel into an ammine complex to form a nickel sulfate ammine complex solution, and then supplying hydrogen gas to the nickel sulfate ammine complex solution to reduce nickel ions to produce a nickel powder. There is.

In the above method of reducing nickel ions using hydrogen gas, it is generally carried out using a high temperature and high pressure vessel such as an autoclave because the reaction does not proceed efficiently unless it is under high temperature and high pressure.
When hydrogen gas is blown into the aqueous solution of nickel sulfate ammine complex under high temperature and pressure using this high temperature and high pressure vessel, a fine tube called a lance called a blowing tube or a sinter is used to efficiently react nickel ions and hydrogen gas. In many cases, hydrogen gas is blown in using a blow pipe having a large number of blow holes.

However, in the case of using the above-described blow pipe, nickel often precipitates in the nickel sulfate ammonium complex solution to generate scaling, and there is a problem that lance blockage occurs as scaling progresses. For this reason, it took the effort and expense of removing scaling regularly and replacing a lance.
Furthermore, when hydrogen gas is blown into the aqueous solution of nickel sulfate ammonium complex using a lance, the concentration of hydrogen gas in the solution of nickel ammonium sulfate complex at a specific location such as near the discharge port of the lance becomes locally high. Partial reduction proceeds and nickel powder with nonuniform particle size may precipitate and grow, which has been a problem in terms of product homogenization.

JP, 2015-140480, A

  The present invention is a method of blowing hydrogen gas under high temperature and pressure and reducing treatment to obtain nickel powder, in which hydrogen gas is blown into a nickel sulfate ammonium complex solution stored in a high temperature and high pressure container under high temperature and pressure condition. In addition, the present invention proposes a method for producing nickel powder in which nickel ions in an aqueous solution and hydrogen gas blown are efficiently reacted to obtain homogeneous nickel powder and nickel powder of uniform size is stably obtained. .

  A first invention of the present invention for solving the above-mentioned problems is a reaction between a nickel sulfate ammonium complex solution and hydrogen gas in a high temperature and high pressure vessel, and reduction of nickel ions in the nickel sulfate ammonium complex solution with hydrogen gas. In the method for obtaining nickel powder, after forming a two-phase state of liquid phase portion-gas phase portion using the nickel sulfate ammonium complex solution as a liquid phase in the high temperature and high pressure vessel, the hydrogen gas is formed into the gas phase The gas phase and the liquid phase form a gaseous phase constituted by the hydrogen gas and a liquid phase constituted by the nickel sulfate ammine complex solution by spraying the liquid surface of the nickel sulfate ammine complex solution in a stirring state. The nickel ion in the nickel sulfate ammonium complex solution is subjected to reduction treatment with the hydrogen gas to generate a nickel powder by making contact at the interface. A method for producing nickel powder.

  A second invention of the present invention is characterized in that the amount of hydrogen gas supplied is adjusted so that the pressure of the gas phase part in the first invention is maintained in the range of 2.5 MPa or more and 3.5 MPa or less. It is a manufacturing method of nickel powder.

  A third invention of the present invention is characterized in that hydrogen gas is blown in while maintaining the temperature range of 150 ° C. or more and 185 ° C. or less in the liquid phase portion and the gas phase portion in the first and second inventions. Manufacturing method of nickel powder

Further, according to a fourth invention of the present invention, in the nickel sulfate ammonium complex solution according to any of the first to third inventions, “Ni / NH ₃ ” is 1.9 or more, 2 in a value representing nickel and ammonia in molar concentration. A method of producing a nickel powder having a composition of 1 or less and containing 100 g / L or more and 500 g / L or less of ammonium sulfate as a buffer.

  The fifth invention of the present invention is the nickel sulfate ammonium complex solution according to any of the first to fourth inventions, wherein nickel powder is used as a seed crystal in an amount of 1 to 100% by weight based on the weight of nickel in the nickel sulfate ammonium complex solution. It is a manufacturing method of nickel powder characterized by using the slurry formed by adding the amount which becomes, in place of the nickel sulfate ammonium complex solution.

  According to the present invention, fine and uniform sized nickel powder can be stably obtained.

It is a SEM image (x100) of the nickel powder obtained in Example 1. FIG. It is a SEM image (x 500) of the nickel powder obtained by the comparative example 1. FIG.

  The present invention is a method of reducing nickel ammine complex solution with hydrogen gas to obtain nickel powder, wherein hydrogen gas is blown into the gas phase of a reaction vessel, and more specifically, the hydrogen gas is stirred. The nickel ions in the complex solution are reduced by the hydrogen of hydrogen gas by the reduction reaction by hydrogen that is sprayed toward the surface of the complex solution being diffused and diffuses from the gas-liquid phase interface to the interior of the solution with the surface of the complex solution as the contact surface. It is reduced to form nickel powder.

By the way, when blowing in the gas with low solubility to a solution like hydrogen, in order to contact with a solution efficiently, generally the method of blowing in a liquid phase is taken.
However, since the solubility of hydrogen gas in the liquid phase in the state under high temperature and pressure is larger than that in the normal pressure, the reaction between hydrogen and the solution is more likely to proceed than under normal pressure when hydrogen gas is blown into the solution. As a result, it has been found that the concentration of hydrogen gas locally increases near the discharge port of the blow pipe used for blowing hydrogen gas, and as a result, it tends to become nickel powder of nonuniform size.

  Therefore, in the present invention, the high temperature and high pressure vessel is provided with two phases, a liquid phase and a gas phase, and the liquid phase is occupied by the stored complex solution, and hydrogen gas is blown into the gas phase. The hydrogen gas is diffused into the solution through the liquid phase of the complex solution (or slurry) stored in the liquid phase and the liquid phase of the complex solution (or slurry) constituting the liquid phase and the hydrogen gas to diffuse the hydrogen gas into the solution. As a result, it is possible to stably obtain nickel powder of uniform size.

In the method of the present invention in which gas is diffused through the interface between the liquid phase and the gas phase for reaction, the partial pressure of hydrogen gas in the gas phase is controlled to be constant, and the penetration of hydrogen gas into the liquid phase is constant. It is important to maintain
For this purpose, the reaction temperature is 150 ° C. or more and 185 ° C. or less, preferably 180 ° C. or more and 185 ° C. or less at which hydrogen gas can obtain a practically sufficient reaction rate for reducing nickel ions in the nickel ammine complex solution. Maintain in the following temperature range.
At temperatures below 150 ° C., the reaction rate is extremely slow and not practical. On the other hand, even if the temperature exceeds 185 ° C., an increase in energy can not be expected but an improvement in reaction rate can not be expected, and an additional burden on equipment is not preferable.

Further, the present invention is characterized in that the hydrogen blown into the gas phase part is uniformly reacted by diffusing into the complex solution (or slurry) in the liquid phase part.
For this purpose, the reaction temperature is not only in the above-mentioned suitable region, but the internal pressure in the vessel, ie, the gas phase portion is 2.5 MPa or more and 3.5 MPa or less, preferably 3.0 MPa or more and 3.5 MPa or less It is necessary to maintain the pressure by adjusting the flow rate of hydrogen gas to maintain the By maintaining this pressure range, hydrogen gas in the gas phase uniformly diffuses into the liquid phase and the reduction reaction proceeds uniformly, and as a result, it is possible to obtain homogeneous nickel powder having the same particle size.
The point at which the internal pressure no longer changes even if the supply of hydrogen gas is stopped is the state in which the reduction with hydrogen does not proceed, that is, the state in which the reaction is completed.

Moreover, as for the slurry containing the nickel sulfate ammonium complex solution, it is preferable that the ratio “Ni / NH ₃ ” of the value of nickel and ammonia expressed in molar concentration is 1.9. Below 1.9, some nickel does not form an ammine complex, and a nickel hydroxide precipitate is formed. If the value exceeds 1.9, ammonia is excessive, which is not preferable, so the upper limit is preferably limited to about 2.1.

  Moreover, it is preferable that the ammonium sulfate density | concentration used as a buffer is 100-500 g / L. If it exceeds 500 g / L, solubility will be exceeded, crystals will precipitate, and it is difficult to achieve less than 100 g / L in terms of the metal balance of the process.

  Furthermore, it is preferable to set it as the composition containing the quantity of the range of 1 weight% or more and 100 weight% or less with respect to the nickel weight in a complex solution as a seed crystal. If the amount is less than 1% by weight, the amount of seed crystals is insufficient and the reduction efficiency is reduced, and the addition of an amount exceeding 100% by weight has no effect on the effect, resulting in an excessive addition.

  Hereinafter, the present invention will be further described by way of examples.

In a stainless steel high-temperature and high-pressure vessel with an internal volume of 2.6 L, 1.0 L of a slurry of a nickel sulfate ammonium complex solution was charged. The composition of the slurry used was a nickel sulfate complex solution having a Ni concentration of 75 g / L and ammonium sulfate (an ammonium sulfate) of 330 g / L, and a nickel powder separately prepared as a seed crystal was further mixed to 75 g / L. .
In addition, what provided the stirrer of an electromagnetic induction type was used for the high temperature / high pressure container, and the stirring blade in a container was stirred at 400 rotations / minute.

Next, while maintaining the above slurry at a temperature of 185 ° C., the internal pressure of the high temperature / high pressure container is 3 while blowing hydrogen gas at 0.1 to 2.0 L / min into the gas phase part between the inside of the high temperature / high pressure container and the slurry. It was maintained at .5 MPa.
Specifically, while blowing hydrogen gas at a flow rate of up to 2.0 L / min from the ceiling of the high-temperature and high-pressure vessel, the hydrogen gas injection amount is adjusted so that the pressure of the high-temperature and high-pressure vessel becomes 3.5 MPa. Adjusted in the range of
The time until hydrogen gas supply was stopped while the pressure of the high-temperature and high-pressure vessel was maintained at 3.5 MPa after the start of blowing hydrogen gas was 31 minutes, which corresponds to the reaction time.

  After completion of the reaction, the mixture was cooled to a temperature of 100 ° C. or less, then the high-temperature and high-pressure vessel was opened, and the slurry in the vessel was solid-liquid separated into solid content and filtrate using filter paper and a Nutche. The obtained solid content, ie, nickel powder, was washed with water, vacuum dried, and then weighed. On the other hand, the filtrate was subjected to component analysis using ICP.

The reduction ratio of nickel ions to nickel powder calculated from the solid content and the nickel concentration of the filtrate after reaction was 99.3%.
The electron micrograph of the nickel powder obtained by reaction is shown in FIG. As can be seen in FIG. 1, uniform nickel powder was obtained.

A reduction treatment was performed under the same conditions as in Example 1 except that the seed crystal nickel powder was not added, to produce a nickel powder.
The reaction time was 16 minutes, and the reduction rate of the obtained nickel powder was 89.6%.

(Comparative example 1)
The nickel sulfate ammonium complex solution was reduced under the same equipment and conditions as in Example 1 except that hydrogen gas was blown directly into the bottom of the slurry using a blow pipe with an inner diameter of 6φ to obtain a nickel powder. The time until hydrogen gas was not consumed was 30 minutes.

The reduction rate of nickel ions to nickel powder calculated from the solid content and the nickel concentration of the filtrate after reaction was 99.3%.
The electron micrograph of the nickel powder obtained by reaction is shown in FIG. Compared with FIG. 1 of the nickel powder according to the present invention, it can be seen that the partially secondarily grown nickel powder is nonuniform in size.

Claims (5)

In a method of reacting nickel sulfate ammonium complex solution and hydrogen gas in a high temperature and high pressure vessel, and reducing nickel ions in the nickel sulfate ammonium complex solution with hydrogen gas to obtain nickel powder,
After forming a two-phase state of a liquid phase portion and a gas phase portion in which the nickel sulfate ammonium complex solution is used as a liquid phase in the high temperature and high pressure container,
The hydrogen gas is blown into the gas phase part and sprayed onto the liquid surface of the nickel sulfate ammonium complex solution in a stirring state to form a gas phase composed of the hydrogen gas and a liquid phase composed of the nickel sulfate ammonium complex solution, A method for producing a nickel powder, wherein nickel ions in the nickel sulfate ammonium complex solution are reduced by the hydrogen gas to generate nickel powder by bringing the nickel ions in the nickel sulfate ammonium complex solution into contact with each other at the interface where a gas phase and a liquid phase form.   The method for producing nickel powder according to claim 1, wherein the amount of hydrogen gas supplied is adjusted such that the pressure in the gas phase part is maintained in the range of 2.5 MPa or more and 3.5 MPa or less.   The method for producing nickel powder according to claim 1 or 2, wherein hydrogen gas is blown while maintaining the temperature range of 150 ° C to 185 ° C in the liquid phase portion and the gas phase portion. The above-mentioned nickel ammonium sulfate complex solution has a composition in which “Ni / NH ₃ ” in the value of the concentration of nickel and ammonia in molar concentration is at least 1.9 and at most 2.1, and 100 g of ammonium sulfate as a buffer The manufacturing method of the nickel powder of any one of Claims 1-3 containing L or more and 500 g / L or less.   The nickel sulfate ammonium complex solution is a slurry formed by adding an amount of 1 to 100% by weight based on the weight of nickel in the nickel sulfate ammonium complex solution using nickel powder as seed crystals to the nickel sulfate ammonium complex solution. The method for producing a nickel powder according to any one of claims 1 to 4, which is used in place of