JPH083130B2 - Extraction and Separation Method of Cobalt from Mixture of Cobalt Oxide and Nickel Oxide with Organic Solution-Water Mixed Solution Containing Alkyl Phosphoric Acid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention selects cobalt from a mixture of cobalt oxide and nickel oxide by using a mixed solution of an organic solution containing alkylphosphoric acid and water. The present invention relates to a method of dissolving, extracting and separating from nickel.

[Prior Art] Conventionally, a method of recovering cobalt and nickel from oxide ore or the like has been studied. However, they are a method in which cobalt oxide and nickel oxide are dissolved at high temperature and high pressure mainly with sulfuric acid or a mineral acid such as hydrochloric acid, and then cobalt and nickel are extracted and separated from the leachate by a solvent extraction method.

[Problems to be Solved by the Invention] In the conventional method, an oxide ore or the like is dissolved under high temperature and high pressure using an acidic solution such as a mineral acid, and then alkali is added to adjust the pH range to which the solvent extraction method can be applied. Addition is indispensable, and there is a problem in that energy such as heating and pressurization and consumption of alkali affect the economic efficiency of the process.

[Means for Solving the Problem] The present inventor uses a mixed solution of an organic solution containing alkylphosphoric acid and water as a base to form cobalt oxide from cobalt oxide as an organic solution at a relatively low temperature. The present invention was found to be carried out by dissolution extraction in a phase, and studies were conducted to utilize it for the separation of cobalt and nickel, leading to the present invention. As the alkyl phosphoric acid used in the present invention,
For example, bis-2-ethylhexyl phosphate and bis-phosphate
An alkyl group having 6 or more carbon atoms such as 2-dodecyl is used. The organic solvent for diluting these may be one that is well mixed with the alkyl phosphoric acid and has a low solubility in water. Examples of such solvents include aliphatic hydrocarbons and aromatic hydrocarbons. Can be found. Water mixed with the organic solution containing alkyl phosphoric acid is adjusted to pH 1.5 or more by adding sulfuric acid, for example. Further, cobalt oxide and nickel oxide have the forms of CoO and NiO, respectively. In the present invention, it suffices to mix a turbid liquid obtained by mixing an organic solution containing an alkylphosphoric acid and water whose pH is adjusted with a mixture of cobalt oxide and nickel oxide and bring them into sufficient contact by stirring or the like. Cobalt is selectively dissolved and extracted in an organic solution containing alkylphosphoric acid.

After the extraction, the organic phase and the water / solid phase can be easily separated by standing or centrifugation.

The cobalt extracted in the organic solution can be easily back-extracted with sulfuric acid or the like.

Since the separated water contains almost no metal components (cobalt and nickel in the present invention), the solid content can be reused for the extraction reaction after filtration after adjusting the pH.

Further, when the waste water is used, it can be discharged as it is by adsorbing and separating a small amount of the dissolved alkylphosphoric acid with activated carbon and neutralizing it with a small amount of alkali.

The present invention includes a process of extracting cobalt directly from a cobalt oxide into an organic phase and a process of extracting cobalt ions dissolved from a cobalt oxide into an organic phase by an aqueous solution acidified by a proton released from an alkylphosphoric acid. It is an extraction reaction that occurs in parallel.

^{_{1 RH O R - O + H}} + a CoO + 2H + a Co 2+ a + H 2 O a 2 CoO + 2RH O CoR 2O + H 2 O a (. Subscripts a and o each show call after aqueous organic phase) of the two During the reaction process, cobalt oxide functions as a base, and the protons released by the alkylphosphoric acid function as an acid.

In addition, it is considered that the presence of water has a larger effect on the endothermic reaction process such as dehydration reaction accompanying the organic phase transition of the metal ion than the exothermic reaction process in which the metal element directly moves to the organic phase, and therefore the endothermic reaction as a whole Therefore, as shown in Example 2, in the present invention, it is considered that the higher the temperature is 50 ° C. or higher, the better the extraction efficiency becomes.

[Advantages and Uses of the Invention] According to the present invention, since cobalt oxide itself is used as a base, it is not necessary to add an alkali from the outside, and a reaction takes place at a relatively low temperature and energy consumption is small. Further, the cobalt extracted in the organic solution can be easily back-extracted with sulfuric acid, which is suitable for the subsequent processes such as electrolysis. Further, the organic solution containing alkylphosphoric acid has an effect that it can be reused after back-extracting cobalt. Further, the present invention is suitable for separating cobalt and nickel.

[Examples] Next, examples of the present invention will be described.

Example 1 A solution system consisting of an organic solution consisting of an xylene solution containing 10% by volume concentration of bis-2-ethylhexyl phosphate (D2EHPA) and an equal volume of water, with a solid-liquid concentration of 2.5 g / l and a particle size, respectively.
Cobalt oxide and nickel oxide of 200 mesh or less,
Table 1 shows the influence of the initial pH of water on the leaching rate of cobalt oxide and nickel oxide and the cobalt concentration in the organic solution when reacted at a stirring speed of 900 rpm, a reaction time of 6 hours and a reaction temperature of 70 ° C. Show.

Example 2 A solution system consisting of an organic solution consisting of a xylene solution containing 10% by volume of D2EHAPA and an equal volume of water (initial pH 6), 2 solid-liquid concentrations of 2.5 g / l each, cobalt oxide and nickel having a particle size of 200 mesh or less. Stir the oxide at 900 rpm for a reaction time of 6
Table 2 shows the influence of the reaction temperature on the leaching rate of cobalt oxide and nickel oxide and the cobalt concentration in the organic solution when they are reacted for a certain period of time.

Table 3 shows the influence of the reaction time on the leaching rate of cobalt oxide and nickel oxide and the cobalt concentration in the organic solution at the reaction temperature of 70 ° C. However, other reaction conditions are the same.

Example 3 A solution system consisting of an equal volume of an organic solution and water (initial pH 6), a cobalt oxide and a nickel oxide each having a solid-liquid concentration of 2.5 g / l and a particle size of 200 mesh or less, a stirring speed of 900 rpm and a reaction time of 6 Table 4 shows the influence of the concentration of D2EHPA in the organic solution when the reaction was carried out at a reaction rate of 70 ° C for a time.

Claims (1)

[Claims] 1. A method for selectively dissolving, extracting and separating cobalt directly from a mixture of cobalt oxide and nickel oxide by using a mixed solution of an organic solution containing alkylphosphoric acid and pH-adjusted water.