KR102529742B1 - Method for solvent extraction of Mo(IV) and Re(VII) - Google Patents

Abstract

The present invention relates to sequential extraction of molybdenum [Mo(VI)] and rhenium [Re(VII)] from aqueous solutions in different media using liquid-liquid extraction techniques, followed by selective extraction of Re(VII).

Description

Method for solvent extraction of Mo(IV) and Re(VII) {Method for solvent extraction of Mo(IV) and Re(VII)}

The present invention relates to sequential extraction of molybdenum [Mo(VI)] and rhenium [Re(VII)] from aqueous solutions in different media using liquid-liquid extraction techniques, followed by selective extraction of Re(VII).

Rhenium and molybdenum are companion metals often found in naturally occurring sulfide minerals such as molybdenum and porphyry copper ores. In fact, rhenium is extracted primarily as a by-product of these ores through hydrometallurgical extraction routes, usually involving roasting-leaching followed by ion exchange techniques. In the process of roasting the ore, rhenium volatilizes above 600°C to form Re2O7 and mixes with flue dust. Flue dust also rubs volatilized rhenium with dilute acid to form a dissolved aqueous species of Re(VII), ReO4-. Molybdenum oxide collected with the flue dust also dissolves to form the Mo(VI) species, namely MoO42-. Due to the anionic compounds and the two metal species exhibiting properties similar to lanthanide shrinkage, their effective separation in hydrometallurgy is a difficult task. On the other hand, listings as market value, supply versus demand, and energy essentials indicate that they should be separated from each other.

In the prior art rhenium separation and recovery have been claimed from different source materials and from different solution media. Most of them used an ion exchange process using an anionic resin for rhenium adsorption and elution from the aqueous feed. The application of solvent extraction in rhenium smelting is very limited to the formation of similar types of anionic species of the two metals. Even in waste alloys, separation of rhenium is carried out by means of anion exchange resins. Several drawbacks were identified when using the ion exchange process, such as long run time with number of unit operations, low loading capacity, and slow mass transfer rate.

Since then, several methods have been reported using solvent extraction with the potential for high mass transfer rates and larger loading capacities [US3681016A; KR101600334B1]. Using an amine solvent, Mo(VI) and Re(VII) are co-extracted from the scrubbed solution of the molybdenum roaster. The loaded organics removed with ammonium hydroxide solution were crystallized/precipitated to recover molybdate and the mother liquor was solvent extracted again with an amine extractant. The loaded organics and stripped raffinate stripped with sodium hydroxide solution are contacted with pyridine to finally extract the rhenium value by distillation [US3681016A]. The repetitive extractions and energy required for crystallization/precipitation/distillation were identified disadvantages of this process, besides selectivity towards other anionic impurities present in the solution. On the other hand, phosphinic acid solvent is mainly used to extract Mo(VI) rather than Re(VII), and subsequently contacting raffinate with phosphine oxide extracts Re(VII) [KR101600334B1]. The phosphinic acid product used in the patent has the disadvantage of being expensive. Therefore, there is a need for a study of a method enabling selective extraction with enhanced metal loading at lower cost and lower extractant consumption.

US Patent Publication No. 3681016 Korean Patent Registration No. 10-1600334

The present invention seeks to provide extraction and separation behavior for the sequential separation of Mo(VI) and Re(VII) in different acidic media.

In addition, the present invention is to provide a method for recovering a high-purity stripped solution of Mo(VI) and Re(VII) metals with quantitative efficiency.

In order to solve the above problems,

In one embodiment, the present invention comprises the steps of extracting Mo (VI) by mixing an oxime (oxime)-based chelate extractant in an aqueous solution containing Mo (VI) and Re (VII); And extracting Re (VII) using a mixture of liquid phosphine oxides and phosphonium-based ionic liquid in the raffinate produced after extracting Mo (VI). Methods for solvent extraction of Mo(IV) and Re(VII) are provided.

The Mo(VI) may be dissolved in the aqueous phase, and the Re(VII) may form a raffinate that remains undissolved.

The oxime-based chelate extractant may be composed of a phenol group and a carboxylic acid derivative showing a cation exchange mechanism forming metal chelation.

The liquid phosphine oxide is dioctyl-monohexyl phosphine oxide, mono-octyl dihexyl phosphine oxide, tri-hexyl phosphine oxide oxide) and tri-n-octyl phosphine oxide.

The concentration of the oxime-based chelate extractant may be 1 to 10 vol.%.

The phosphonium-based ionic liquid may include a phosphonium-based ionic liquid exhibiting an anion exchange mechanism and having an anionic functional group.

The concentration of the organic mixture of the liquid phosphine oxide and the phosphonium-based ionic liquid in the raffinate may be 0.5 to 5 vol.%, and the phosphonium-based ionic liquid may contain 0.01 to 1 mol/L.

The solvent extraction method of Mo(IV) and Re(VII) of the present invention includes a two-step sequential extraction process of Mo(VI) to Re(VII). This is because an oxime-based liquid ion exchange extractant is applied for Mo(VI) extraction to produce a higher separation coefficient value (β[Mo/Re]), and liquid phosphine oxide and phosphonium-based ions for e(VII) extraction. More than 98% of Mo(VI) and Re(VII) can be recovered by using an organic mixture of liquids.

Figure 1 shows the effect of aqueous medium on the metal extraction efficiency of Mo(VI) and Re(VII) as a function of equilibrium pH (pH[eq]) according to an embodiment of the present invention.
Figure 2 shows the effect of aqueous media on the metal extraction efficiency of Mo(VI) and Re(VII) as a function of extractant concentration according to an embodiment of the present invention.

Since the present invention can make various changes and have various embodiments, specific embodiments will be illustrated in the drawings and described in detail in the detailed description.

However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

In the present invention, the term "comprises" or "has" is intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

The solvent extraction method of Mo(IV) and Re(VII) of the present invention includes a two-step sequential extraction process of Mo(VI) to Re(VII). For the selective extraction of Mo(VI) over Re(VII), an oxime-based chelating extractant is first used to leave Re(VII) unextracted into the aqueous phase. To this end, an oxime-based liquid ion exchange extractant is applied, resulting in higher separation coefficient values (β[Mo/Re]). Additionally, the Mo(VI)-depleted raffinate is treated for Re(VII) extraction using an organic mixture of liquid phosphine oxide and phosphonium-based ionic liquid. More than 98% of Mo(VI) and Re(VII) can be recovered by the process of the present invention.

Hereinafter, the present invention will be described in detail.

The present invention comprises the steps of extracting Mo (VI) by mixing an oxime (oxime)-based chelating extractant with an aqueous solution containing Mo (VI) and Re (VII); and extracting Re(VII) using an organic mixture of liquid phosphine oxides and phosphonium-based ionic liquid in raffinate generated after extracting Mo(VI). A method for solvent extraction of Mo(IV) and Re(VII) is provided.

The Mo(VI) may be dissolved in the aqueous phase, and the Re(VII) may form a raffinate that remains undissolved.

The oxime-based chelate extractant may be composed of a phenol group and a carboxylic acid derivative showing a cation exchange mechanism forming metal chelation.

The liquid phosphine oxide may include a mixture of dioctyl-monohexyl phosphine oxide, mono-octyl dihexyl phosphine oxide, tri-hexyl phosphine oxide and tri-n-octyl phosphine oxide.

The concentration of the oxime-based chelate extractant may be 1 to 10 vol.%. For example, the concentration will be 1 to 8 vol.%, 1 to 6 vol.%, 1 to 4 vol.%, 2 to 10 vol.%, 4 to 10 vol.% or 6 to 10 vol.% can

The carrier of the oxime-based chelate extractant may include organic aromatic hydrocarbons such as kerosene, Exxol D80, and Solvesso. Here, the carrier may mean a diluent used to dilute the extractant.

The phosphonium-based ionic liquid may include a phosphonium-based ionic liquid exhibiting an anion exchange mechanism and having an anionic functional group. For example, the phosphonium-based ionic liquid may be a phosphonium-based ionic liquid having a molecular weight of 350 g/mol or more.

The concentration of the organic mixture of the liquid phosphine oxide and the phosphonium-based ionic liquid in the raffinate may be 0.5 to 5 vol.%, and the phosphonium-based ionic liquid may contain 0.01 to 1 mol/L. For example, the concentration of the mixture may be 0.5 to 3 vol.%, 0.5 to 2 vol.%, 1 to 5 vol.%, 2 to 5 vol.%, or 3 to 5 vol.%.

The carrier of the organic mixture of liquid phosphine oxide and phosphonium-based ionic liquid in the raffinate may include organic aromatic hydrocarbons such as kerosene, Exxol D80, Solvesso, and the like. Here, the carrier may mean a diluent used to dilute the mixture.

The extraction performed may be in two stages at the countercurrent junction. This may mean a double contact, and after carrying out metal extraction in an aqueous solution in a single step contact, the remaining metal in the raffinate is again contacted with an organic extractant to take all metal ions from the aqueous phase to the organic phase. there is.

The Re(VII) containing raffinate can be processed in two stages in the countercurrent junction yielding 99.3% extraction efficiency.

In the solvent extraction method of Mo(IV) and Re(VII) of the present invention, loaded organics are subjected to alkali stripping, preferably using NaOH and NH ₄ OH+NH ₄ Cl solution to extract Mo(VI) and Re(VII). (VII) can be stripped to produce highly pure solutions of Na ₂ MoO ₄ and NH ₄ ReO ₄ , respectively. In addition, crystal products of Na ₂ MoO ₄ and NH ₄ ReO ₄ having a purity of 99.9% or more may be prepared by crystallizing the solution. This means that the two metals separately extracted using two different organic extractants (oxime-based chelate extractant and organic mixture) can be recovered from the organic phase to the water phase, respectively. For example, first Mo(VI) is extracted with an oxime-based chelate extractant, and after extraction, the Mo(VI)-containing oxime-based chelate extractant is contacted with an alkaline solution of NaOH/NH ₄ OH to obtain pure Mo(VI). It can be recovered from the organic phase to the aqueous phase in form (i.e. rhenium-free). Similarly, in the next step, Re(VII) is extracted into an organic mixture of liquid phosphine oxide and phosphonium-based ionic liquid, and the organic mixture containing Re(VII) is contacted with an alkaline solution of NaOH/NH ₄ OH to obtain Re( VII) can be recovered from the organic phase in pure form (ie without molybdenum) as an aqueous phase.

Hereinafter, the present invention will be described in more detail through examples and the like according to the present invention, but the scope of the present invention is not limited by the examples presented below.

[Example]

Example 1

For selective extraction of molybdenum [Mo(VI)] over rhenium [Re(VII)], aqueous solutions in different media containing 380 mg/L Re(VII) and 860 mg/L Mo(VI) were equilibrated. Separately contacted with 2 vol.% extractant prepared in organic diluent as a function of pH, equilibrated organic to aqueous in a ratio of 1. A 50 mL volume of aqueous feed was equilibrated with an equal volume of organic phase in a 125 mL separatory funnel for 5 minutes. The results are shown in Figure 1. The extraction of Mo(VI) was greatly affected by the equilibrium pH, which showed a large change in extraction efficiency according to the change in the aqueous medium.

In addition, molar separation coefficients of molybdenum-rhenium (β _Mo/Re ) were calculated for each medium as a function of equilibrium pH. The results shown in Table 1 below show that both (acid medium and equilibrium pH) have a significant effect on the separation factor of metal ions, but the maximum β _Mo/Re value is at equilibrium pH 0.2 regardless of the acidic medium used for the aqueous feed. indicated that it can be obtained from

Example 2

Concentration effect of oxime-based chelating extractant into the organic phase by varying the extractant concentration in the range of 0.5 to 5.0 vol.% after obtaining the maximum separation factor (βMo/Re) at equilibrium pH 0.2 regardless of the aqueous feed medium. was experimented with. The organic to aqueous phase ratio was maintained at 1. A 50 mL volume of aqueous feed was equilibrated with an equal volume of organic phase in a 125 mL separatory funnel for 5 minutes. The results are shown in FIG. 2, and it was confirmed that the extraction efficiency of Mo(VI) increased significantly as the concentration of extractant molecules in the organic phase increased using different aqueous feed media.

In addition, the molar separation coefficient of molybdenum-rhenium (β _Mo/Re ) was calculated for each medium as a function of extractant concentration. The results in Table 2 below indicate that a maximum separation factor of 19261 was achieved in sulfate medium, but the order of β _Mo/Re values was obtained in the order of sulfate > nitrate > chloride.

Example 3

The Mo(VI)-depleted raffinate was further treated with a liquid mixture of phosphine oxides (different mass ratios), which was further mixed with an equal concentration of 1 vol.% of a phosphonium-based ionic liquid. Extraction of Re(VII) as a function of organic mixture and equilibrium pH was equilibrated at a ratio of organic to aqueous to one. A 50 mL volume of aqueous feed was equilibrated with an equal volume of organic phase in a 125 mL separatory funnel for 5 minutes. The results shown in Table 3 below do not show significant changes in extraction efficiency with changes in equilibrium pH for nitrate and sulfate medium feeds. However, the chloride medium showed a significant increase in extraction efficiency up to about 80% in a single contact, indicating the compatibility of Re(VII), ReO ₄ ⁻ , and Cl ⁻ ion exchange during the extraction process. Additionally, extraction using an O/A ratio of 2 yielded 99.3% extraction efficiency of Re(VII) using a chloride medium at equilibrium pH 2.0.

Example 4

The loaded organics obtained in Example 2 and Example 3 containing 844.5 mg/L Mo(VI) and 377 mg/L Re(VII), respectively, were stripped for efficient recovery of the two metals and regeneration of the organic phase (stripped) To this end, the loaded organics were contacted with an alkali solution in an O/A ratio of 1, preferably NaOH solution was used for Mo(VI) stripping and NH ₄ OH+NH ₄ Cl solution was used for Re(VII) stripping . Quantitative stripping can be obtained using 0.5 mol/L NaOH for Mo(VI) stripping and 1.0 mol/L total NH ₃ in NH ₄ OH+NH ₄ Cl solution for Re(VII) stripping, which is A recovery efficiency of over 99% was calculated from the loaded organic phase. Table 4 below shows the experimental conditions and results of this example.

Claims (7)

Extracting Mo(VI) by mixing an oxime-based chelating extractant with an aqueous solution containing Mo(VI) and Re(VII); and
Extracting Re(VII) using an organic mixture of liquid phosphine oxides and phosphonium-based ionic liquid in raffinate generated after extracting Mo(VI); ,
The oxime-based chelate extractant is composed of a phenol group and a carboxylic acid derivative showing a cation exchange mechanism forming metal chelation,
The liquid phosphine oxide is dioctyl-monohexyl phosphine oxide, mono-octyl dihexyl phosphine oxide, tri-hexyl phosphine oxide oxide) and tri-n-octyl phosphine oxide,
The phosphonium-based ionic liquid is a phosphonium-based ionic liquid having a molecular weight of 350 g/mol or more,
After extracting the Mo(VI), the Mo(VI)-containing oxime-based chelate extractant is contacted with an alkaline solution of NaOH/NH ₄ OH to recover Mo(VI) in pure form from the organic phase to the aqueous phase, and the Re(VII) ) is extracted and then the organic mixture containing Re(VII) is contacted with an alkaline solution of NaOH/NH ₄ OH to recover Re(VII) from the organic phase to the aqueous phase in pure form as a solvent for Mo(IV) and Re(VII). extraction method.
According to claim 1,
In the step of extracting Mo (VI),
A method for solvent extraction of Mo(IV) and Re(VII), characterized in that the Mo(VI) is dissolved in the aqueous phase and the Re(VII) remains undissolved to form a raffinate.
delete delete According to claim 1,
The solvent extraction method of Mo (IV) and Re (VII), characterized in that the concentration of the oxime-based chelate extractant is 1 to 10 vol.%.
delete According to claim 1,
The concentration of the organic mixture of the liquid phosphine oxide and the phosphonium-based ionic liquid in the raffinate is 0.5 to 5 vol.%, and the phosphonium-based ionic liquid comprises 0.01 to 1 mol / L Characterized in that Solvent extraction method of Mo(IV) and Re(VII).

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