JPS6046049B2 - Method for purifying nickel chloride aqueous solution - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for removing free hydrochloric acid from an aqueous nickel chloride solution containing free hydrochloric acid to obtain a purified aqueous nickel chloride solution.

The conventional method for producing nickel chloride was to obtain crystalline nickel chloride in the form of hexahydrate from an aqueous nickel chloride solution obtained by dissolving electrolytic nickel with chlorine.

Such an aqueous nickel chloride solution does not contain free hydrochloric acid and can be used as a product as crystals as it is, and when crystal 25y is dissolved in 500 mι of water, the pH is 5 or more, but the cost is high. In order to obtain highly pure nickel in recent nickel hydrometallurgical methods, nickel-cobalt mixed sulfide obtained when removing cobalt from an aqueous solution containing a small amount of cobalt in addition to nickel is used as a raw material.
For the purpose of recovering cobalt and nickel from this, this mixed A-1 '14tAΓ bJw
ITIre$↓Mrr&U-Mountain 1-wf--, a gel cobalt sulfate aqueous solution is obtained, and the nickel and cobalt components are extracted into the organic solvent using an organic solvent such as versatic acid. is extracted with hydrochloric acid to remove nickel and
A cobalt mixed chloride aqueous solution is obtained, and the cobalt component is extracted from this mixed chloride aqueous solution using an organic solvent such as tri-normal octylamine, leaving the nickel chloride component in the aqueous solution. The cobalt component is back-extracted with hot water to obtain an aqueous nickel chloride solution and an aqueous cobalt chloride solution, and these aqueous solutions are subjected to electrolysis or the like to obtain metallic nickel and cobalt. Therefore, collecting nickel chloride crystals from the nickel chloride aqueous solution during these processes can greatly contribute to cost reduction, but as mentioned above, the nickel chloride aqueous solution that has gone through the solvent extraction process contains free hydrochloric acid. is unavoidable and usually contains 5 to 10 y/l of free hydrochloric acid.

In this way, when nickel chloride containing free hydrochloric acid is crystallized (as is), the pH value of the crystal (25y of crystal is 500% of water)
The problem is that the PH value of the solution (when dissolved in 1 ml) is low, and it cannot be used as a commercial product as it is.

Therefore, it is necessary to remove free hydrochloric acid before crystallization, and one method for this is to neutralize free hydrochloric acid using nickel carbonate or nickel hydroxide. Since a small amount of Na is usually mixed in, the neutralization operation causes Na to be mixed into the nickel chloride aqueous solution, which deteriorates the quality of the product unless it neutralizes a very small amount of free hydrochloric acid. An object of the present invention is to provide a method for removing free hydrochloric acid contained in an aqueous nickel chloride solution without introducing impurities, while eliminating the above-mentioned drawbacks.

In order to achieve this object, the present invention uses a diffusion dialysis device to dialyze only the hydrochloric acid contained in water to remove a nickel chloride aqueous solution containing free hydrochloric acid. A flow rate of 112 or less water is supplied to the diffusion chamber side to obtain a diffusion liquid containing a higher concentration of hydrochloric acid than the concentration of hydrochloric acid in the stock solution, thereby reducing the hydrochloric acid content in the post-dialysis solution. There are things that I did.

The inventor investigated the removal of hydrochloric acid from an aqueous nickel chloride solution and an advantageous method for recovering hydrochloric acid by varying the supply amount of the stock solution and water per dialysis membrane area; as a result, the present invention was achieved. When attempting to remove sulfuric acid from a nickel sulfate aqueous solution mixed with sulfuric acid in the same manner, the phenomenon that the sulfuric acid in the diffusion solution becomes more concentrated than the original solution as in the present invention was not observed.

This means that the active amount of hydrogen ions in an aqueous solution containing hydrochloric acid differs from that in the case of hydrochloric acid alone depending on the coexisting nickel chloride, and is independent of the hydrochloric acid concentration, and is based on the relationship expressed by the exponential function of the nickel chloride concentration. This is thought to be due to changes in the temperature. Therefore, the same gist of the present invention can be applied to the case where hydrochloric acid is to be removed from an aqueous solution of a metal chloride containing hydrochloric acid, such as an aqueous solution of sodium chloride, magnesium chloride, cobalt chloride, or the like. This is thought to be because when attempting to recover sulfuric acid from a metal sulfate aqueous solution containing sulfuric acid using a dialysis membrane, the activity of hydrogen ions can always be considered to be 1. According to the present invention, most of the hydrochloric acid can be removed from an aqueous nickel chloride solution containing free hydrochloric acid without contaminating impurities, and the concentration of the recovered hydrochloric acid can be increased, making it easy to use in subsequent processes, and compared to conventional methods. It is economical compared to

Examples will be described below.

Example: A stock solution of a nickel chloride aqueous solution containing free hydrochloric acid containing about 15 to 20 y/e1 of free hydrochloric acid and about 130 y/e of nickel as nickel chloride was added to the dialysis room side of a diffusion dialysis apparatus with an effective membrane area of 78 d at room temperature at a concentration of about 10 e/MIn. A dialysis test was conducted by supplying water at a ratio of 9.5 to 2.0'/Mln to the diffusion chamber side.

The test results are shown in Table 1. From the above results, free hydrochloric acid contained in the stock solution shows a removal rate of 70% or more even when the flow rate ratio of water to stock solution is changed from 1:1 to 1:5, and free hydrochloric acid in the post-dialysis solution shows a large removal rate. Although the concentration of free hydrochloric acid in the diffusion liquid decreased considerably, it was still the test NO. Water to stock ratio of 2 or less is 1
: If it is 2 or more, the concentration of free hydrochloric acid in the diffusion liquid is more than twice that of the stock solution, which is convenient for use and recovery in subsequent steps.

Claims (1)

[Claims] 1 In a method of obtaining a purified nickel chloride aqueous solution by removing free hydrochloric acid from a nickel chloride aqueous solution containing free hydrochloric acid, 1 of the flow rate of the stock solution supplied to the dialysis room side of the diffusion dialysis apparatus.
1. A method for purifying an aqueous nickel chloride solution, which comprises supplying an amount of water equal to or less than 1/2 to a diffusion chamber to obtain a diffusion liquid containing a higher concentration of hydrochloric acid than the concentration of hydrochloric acid in the stock solution.