Mikiya Tanaka

Mikiya Tanaka
National Institute of Advanced Industrial Science and Technology

Dr. Eng.
Solvent extraction of rare earths, nickel, copper, and other metals. Hydrometallurgy. Metal recycling.

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137
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Publications

Publications (137)
Article
A novel solvent extraction equilibrium model has been developed to separate nickel and copper from the loaded LIX84-I (active component: 2-hydroxy-5-nonylacetophenone oxime dissolved in a nonpolar diluent, ShellSol D70) formed by the extraction from ammoniacal alkaline solutions. The targeted process consists of the scrubbing of ammonia and subsequ...
Article
The equilibria associated with the solvent extraction of trivalent rare earth elements (REEs) with 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (EHEHPA) have been previously studied by many researchers because of the industrial importance of REEs. However, quantitative analysis has been limited to relatively low concentrations of EHEHPA beca...
Article
To understand the relationship between the structure and function of compounds for the extraction of Pd(II) from HCl solution, we investigated the Pd(II) extraction properties using three sulfide-containing diamides with the same N-substituents, N,Nʹ-dimethyl-N,Nʹ-diphenyl: thiodiglycolamide (mptdga), 3,3ʹ-thiodipropionamide (mptdpa), and 1,2-ethyl...
Article
Separation of precious metals (PMs) is becoming increasingly important because of their growing application in industrial products, such as electronics and catalysts. Most PM separation and purification processes are performed using acidic chloride solutions; therefore, a thorough understanding of the chemical properties and separation mechanisms o...
Article
We have found that a mixture of tri-n-octylamine (TOA) and di-n-hexylsulfide (DHS) in CHCl3 displays synergistic extraction of Ru(III) from aqueous HCl. Approximately 55% of Ru(III) was extracted by a 0.25 M TOA–0.25 M DHS system, whereas a single extractant, 0.25 M TOA or 0.25 M DHS, achieves hardly any Ru(III) extraction. Job plots of the extract...
Article
The effective recovery of Rh(III) from mixtures also containing Pd(II) and Pt(IV) is one of the most difficult tasks in platinum group metal refining. Adding 3,3'-diaminobenzidine (DAB) to 7 and 10 M HCl aqueous solutions containing Rh(III), Pd(II), and Pt(IV) chlorido species affords the effective separation of Rh(III) from Pd(II) and Pt(IV) throu...
Article
Current methods for the extraction of rhodium carry the highest carbon footprint and worst pollution metrics of all of the elements used in modern technological applications. Improving upon existing methods is made difficult by the limited understanding of the molecular-level chemistry occurring in extraction processes, particularly in the hydromet...
Article
The separation of Y(III) from Eu(III) using a hollow fiber-supported liquid membrane with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (EHPNA) as an extractant was studied. The effects of HCl and metal concentrations in the feed solution, the EHPNA concentration in the membrane, and the HCl concentration in the stripping solution on the ini...
Conference Paper
Copper(II) and nickel(II) are often recovered from ammoniacal alkaline solutions by solvent extraction using hydroxyoxime extractants: both copper(II) and nickel(II) are extracted from ammoniacal alkaline solutions and, from the loaded organic phase, nickel(II) is selectively stripped with a dilute acid followed by copper(II) stripping with an acid...
Article
We synthesized polymeric adsorbents modified with diglycolamic acid ligands for the recovery of rare earth elements. Styrene, divinylbenzene, and glycidyl methacrylate were copolymerized by suspension polymerization in the presence of diluent mixtures of heptane and toluene. Varying the composition of the diluent mixtures changed the pore character...
Article
Full-text available
The refining of platinum group metals is based mainly on solvent extraction methods, whereas Ru is selectively recovered by distillation as RuO4. Replacement of distillation by extraction is expected to simplify the purification process. To develop an effective extraction system for Ru, we analyzed the Ru species in HCl with ultraviolet-visible (UV...
Article
The equilibria for the extraction of nickel(II) and ammonia from ammonium salt solutions by using the extractant LIX84-I (active component, 2-hydroxy-5-nonylacetophenone oxime) dissolved in a non-polar diluent, ShellSol D70, were studied at pH 210 and 298 K under different ammonium salt concentrations, kinds of counter anions, aqueous phase pH valu...
Article
Using N,N,N′,N′-tetra-2-ethylhexyl-thiodiglycolamide (TEHTDGA) in n-dodecane as the extractant, we compared the percentages of Pd(II) extracted from HCl and HBr solutions, and analyzed the structures of the Pd(II)–extractant complexes. For comparison, similar experiments were performed with di-n-hexyl sulfide (DHS), a well-known sulfide-type extrac...
Article
Ion-exchange and fractional precipitation using phosphorster coordination polymers have been studied to develop an environmental friendly lanthanide separation method, where only water is used as a solvent. In an ion-exchange system, high selectivity has been found in the lanthanide series. In addition, the selectivity changes depending on the ion...
Conference Paper
Nickel is often recovered via ammoniacal alkaline solution by solvent extraction using a chelating reagent. In this process, a certain amount of ammonia is known to be co-extracted with nickel which is removed by dilute acid scrubbing before stripping of nickel with sulfuric acid. In order to effectively design and control the process, it is import...
Article
Here we examined the equilibrium distribution ratios of copper(II) and ammonia between an ammonium salt solution (nitrate, sulfate, or chloride) and the extractant LIX84I (active component, 2-hydroxy-5-nonylacetophenone oxime) dissolved in a non-polar diluent Shellsol D70 at pH 2–10 and 298 K. The effects of pH, ammonium salt concentration in the a...
Article
To clarify of the adsorption behavior of arsenic ions in alkaline solutions, we conducted arsenic adsorption tests for conventional adsorbents (polymer resin adsorbents and inorganic ion-exchangers). For polymer resin adsorbent, the adsorbent with glucamine groups adsorbed trivalent arsenic ions via hydroxyl groups in glucamine, and the strong base...
Article
The separation properties of Pt(IV) over Fe(III) in HCl solutions using N-2-ethylhexyl-bis(N-di-2-ethylhexyl-ethylamide)amine (EHBAA) were investigated and then compared with those using the conventional extractant tri-n-octylamine (TOA). Also, the structural analyses of Pt(IV) in both of the aqueous (HCl solution) and organic (EHBAA in n-dodecane–...
Article
Solvent extraction of valuable metals such as copper and nickel is often carried out from ammoniacal alkaline solutions with chelating extractants, during which coextraction of ammonia is inevitable. In the present study, as a basis of modeling of the whole ammoniacal extraction process, the equilibrium distribution ratios of ammonia between a 3 mo...
Chapter
There is an increasing attention to recover dilute rare earth elements (REEs) from acidic solutions in order to meet their demands and stabilize their supply chain. Adsorption is suitable for recovering target metal ions when their concentrations are low. Many adsorbents for REEs have been studied; nevertheless, there are no adsorbents in practical...
Article
Thermodynamics of the formation of coordination polymers (CPs) or metal−organic frameworks (MOFs) have not been focused on, while many CPs or MOFs have been synthesized in a solution. With a view to separating Nd³⁺ and Dy³⁺ in an aqueous solution, we demonstrate that crystallization of the CPs of Nd³⁺ and Dy³⁺ based on dibutyl phosphoric acid (Hdbp...
Article
Previously, we investigated bead-type silica gel adsorbents bearing immobilized diglycolamic acid ligands for the recovery of rare earth elements (REEs). Although the ligand-bearing silica gel selectively adsorbs REEs, the ligand loading is limited by the specific surface area of the silica gel. To increase the ligand loading, we have prepared a fi...
Article
Previously, we investigated silica gel adsorbents bearing immobilized diglycolamic acid ligands (designated EDASiDGA) for the selective recovery of rare earth elements (REEs) from acidic solution, but the details of the adsorption mechanism remained to be elucidated. In this study, to clarify the adsorption mechanism, we prepared some derivatives o...
Article
A new Si refining process, which employs molten salt electrolysis and precipitation steps, is proposed and tested. In this process, impure Si is added to a Cu-Si liquid alloy anode, and the electrorefining of Si is conducted using an Al-Si liquid alloy cathode in a fluoride-based molten salt. From the obtained Si-enriched Al-Si alloy, purified Si i...
Article
Due to the impact of increasing global demand for high-grade steel for a variety of applications at a time when high grade iron ore reserves are becoming depleted, the removal of impurities, and especially phosphorus, has become essential. Demand in the rapidly growing car industry, in particular, is increasing pressure on steelmakers to provide hi...
Article
The increasing demand for neodymium (Nd)-magnets containing dysprosium (Dy) has necessitated the recovery of Nd and Dy from magnet scraps to ensure their supply. Thus, it is required to develop an environmentally friendly method for separating Nd3+ and Dy3+. Herein, we show that the formation of coordination polymers based on di(2-ethylhexyl) phosp...
Article
Full-text available
A liquid-liquid countercurrent centrifugal extractor with Taylor vortices which is appropriate for high-performance extraction has been developed. Until now, continuous extraction with more than ten multiple theoretical stages has been demonstrated by a single centrifugal extractor in the case of single specie (zinc extraction with di(2-ethylhexyl)...
Article
Synergistic extraction of Rh(III) from relatively concentrated HCl solution was studied using two mixed solvents (di-n-hexyl sulfide (DHS)-tri-n-octylamine (TOA) and N,N′-dimethyl-N,N′-di-n-octyl-thiodiglycolamide (TDGA)-TOA) in chloroform. The Rh(III) extraction efficiency is poor when 0.5 M TOA, DHS, or TDGA is used independently. In contrast, th...
Article
The recovery of rare earths from ores and scraps requires the selective separation of dilute rare earth ions from solutions containing high concentrations of base metal ions. Using column tests under conditions mimicking practical use, we investigated a novel adsorbent comprising silica gel particles modified with diglycol amic acid groups (EDASiDG...
Article
Extraction of Rh(III) from a HCl solution with N,N-disubstituted amide-containing tertiary amine (ACTA) compounds (N,N-di-n-hexyl(N-methyl-N-n-octyl-ethylamide)amine (MonoAA), N-n-hexyl-bis(N-methyl-N-n-octyl-ethylamide)amine (BisAA), and tris(N-methyl-N-n-octyl-ethylamide)amine (TrisAA)) was investigated. The ACTAs extract Rh(III) more efficiently...
Article
For the recovery of rare earth elements, we previously synthesized an adsorbent consisting of silica gel particles modified with diglycol amic acid groups. In the present study, we optimized the amount of diglycolic anhydride used for the synthesis of the adsorbent and evaluated the utility of the adsorbent in terms of its selectivity for rare eart...
Article
In the present study, extraction of rare earth elements (La, Ce, and Tb) in phosphor using concentrated sulfuric acid followed by water extraction was investigated in order to develop a recycling process of waste phosphor containing rare earth elements (La, Ce, and Tb). As a pretreatment, Y and Eu were leached with 2.0 mol/dm³ sulfuric acid solutio...
Article
A novel adsorbent with a diglycol amic acid frame has been synthesized for the recovery of rare earth elements. The adsorbent has the ability to selectively adsorb rare earth metal ions from solutions containing high concentrations of base metal ions in a low pH region.
Article
An exchange between lanthanide ions (Ln3+) in a solution and coordinated yttrium ions (Y3+) takes place in a coordination polymer (CP) formed by Y3+ and di-(2-ethylhexyl) phosphoric acid (Hdehp). Through this cation exchange, Ln3+ is adsorbed on the CP depending on the coordination power with Hdehp. Accordingly, the Ln3+ with the larger atomic numb...
Article
Full-text available
Against a backdrop of increasing demand, the recovery of neodymium (Nd) and especially dysprosium (Dy) from manufacturing scraps and used magnets has necessitated the development of Nd/Dy separation technologies. To this end, we suggest a simple and environmentally friendly separation method by fractional precipitation of coordination polymers (CPs...
Article
The extraction properties of palladium(II) in an HCl solution with four sulfide-containing monoamide (S-MA) compounds (N-methyl-N-n-octyl-4-thiapentanamide (MO4), N-methyl-N-n-octyl-3-thiapentanamide (MO3), N-methyl-N-n-octyl-phenyl-3-thiapentanamide (MOPh), and N,N-di-n-octyl-3-thiapentanamide (DO3)) were investigated by solvent extraction, FT-IR,...
Article
In this paper the exchange of lanthanide(III) ions (Ln(3+)) between a solution and a coordination polymer (CP) of di(2-ethylhexyl)phosphoric acid (Hdehp), [Ln(dehp)3], is studied. Kinetic and selectivity studies suggest that a polymeric network of [Ln(dehp)3] has different characteristics than the corresponding monomeric complex. The reaction rate...
Article
We have conducted geochemical and mineralogical investigations of the rare earth and yttrium (REY)-rich mud from the Minami-Torishima area in the Pacific in order to clarify the concentration of REY and their host-phase in the mud. X-ray diffraction analysis shows that the mud is mainly composed of phillipsite, fluorapatite, quartz, albite, illite...
Article
In order to observe the impurity behavior during a hydrometallurgical copper recycling process using ammoniacal solution and cuprous ions, copper was recovered from wasted printed circuit boards, where the solution was recycled after adjustment of the solution volume and composition by addition of copper-free solution and oxygen gas. It was confirm...
Article
With the increased concern about the rare-earth supply chain risk, recycling rare-earths from scrap is receiving significant attention. In this monograph, the studies of the rare-earth recycling technologies have been reviewed with respect to magnets, phosphors, batteries, polishing powders and others from the viewpoints of physical separation, hyd...
Patent
Full-text available
The present invention provides a novel separation reagent capable of obtaining a high extraction % of rhodium in a chlorine-based acid solution, which has never existed heretofore, and a method for separating and recovering a platinum group metal using the same. An organic phase composed of an amide-containing tertiary amine separation reagent repr...
Article
Full-text available
Coordination polymers can be attractive ion exchange materials because of their crystallinity and semi-flexibility, which are rather opposing properties, and play integral and synergistic roles in introducing unique ion-exchange behavior. In this paper, Ln(3+)/Ce(3+) exchange (Ln(3+) = Nd(3+), Gd(3+), Dy(3+), or Lu(3+)) in a coordination polymer, [...
Article
Full-text available
The nature of the inner coordination sphere of In(3+) present in both the organic and aqueous solutions during the solvent extraction of In(3+) from an aqueous HCl solution with tri-n-octyl amine (TOA) was investigated by In K-edge XAFS. This information was then used to clarify the details of the extraction properties of indium chloride anion comp...
Article
The exchange of lanthanide(III) ions (Ln(3+)) between a solution and a coordination polymer (CP) formed by cerium(III) or samarium(III) ion and an organophosphorous ligand has been studied. The CPs exhibit distinctive Ln(3+) affinity that varies with a small change in its framework, depending on the central Ln(3+).
Article
The coordination properties of highly concentrated rhodium complexes (Rh: ca. 10 g L−1) in concentrated hydrochloric acid solution upon addition of tin(II) chloride were investigated using Rh and Sn K-edge XAFS spectra. For Rh solutions in the absence of Sn, the Rh ion shows no inner-sphere H2O complexation for [HCl] ≥ 6 M. The coordination structu...
Article
In order to reduce the surface roughness of a copper deposit from cuprous ions in ammoniacal alkaline solutions, optimization of the electrolytic conditions was attempted, and the surface roughness was somewhat improved. Because the improvement was insufficient, the addition of gelatin or polyethylene glycol (PEG) to the electrolyte was then examin...
Article
The separation of Nd(III) and Dy(III) from Fe(III) and Ni(II) in relatively high concentrations of HNO3, HCl and H2SO4 solutions (0.1 - 7 M) was investigated using with 0.1 M N,N′-dimethyl-N,N′-di-n-octyl-diglycolamide (MODGA) in 80 vol% n-dodecane—20 vol% 2-ethylhexanol. In all systems, the extraction percentage (E%) value for Dy(III) is higher th...
Article
Anodic dissolution of tungsten or tungsten carbide in a molten sodium hydroxide bath was investigated at 723K in order to simplify a tungsten dissolution step during tungsten recycling process from secondary resources like used cemented carbide (super hard material) tools. Cyclic voltammetry using tungsten and other metal wire electrodes suggested...
Article
The separation of Nd(III) and Dy(III) from Fe(III) and Ni(II) in relatively high concentrations of HNO3, HCl and H2SO4 solutions (0.1 - 7 M) was investigated using with 0.1 M N,N'-dimethyl-N,N'-di-n-octyl-diglycolamide (MODGA) in 80 vol% n-dodecane-20 vol% 2-ethylhexanol. In all systems, the extraction percentage (E%) value for Dy(III) is higher th...
Article
The solvent extraction equilibrium of zinc with 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (EHPNA) in an alkane diluent, Shellsol D70, was studied at a constant ionic strength of 1 mol/L from nitrate solutions considering the correction of the extractant nonideality in the organic phase by Alstad’s method. On the basis of the slope analysi...
Article
Di-n-hexyl sulfide (DHS) has been widely used as the practical Pd(II) extractant. Although its selectivity of Pd(II) over Pt(IV) is high enough in an acidic chloride solution, the extraction is very slow. In order to accelerate the Pd(II) extraction while retaining its high selectivity and operability, one method is to add an acceleration reagent t...
Article
The leaching efficiencies using both fresh Na<sub align="right"> 2 </sub>EDTA and regenerated Na<sub align="right"> 2 </sub>EDTA on the remediation of contaminated soils from Chenzhou lead-zinc mining area located in southern Hunan Province (southern China) were investigated. The total concentrations of Cd, Pb, Cu and Zn in both contaminated soils...
Chapter
The hydrometallurgical method is one of the key technologies in metal recycling, because it enables the fine separation between chemically-similar metals and a small-scale operation. In this paper, the recent results of our hydrometallurgical recycling studies are outlined. The topics include (i) noble extractants for precious metal separation, (ii...
Article
It is a great pleasure to publish here a special issue of the Journal of Chemical Engineering of Japan titled, “Sustainable Chemical Engineering.” This special issue has been planned by the voluntary members of the Division of Environment, Society of Chemical Engineers, Japan (SCEJ), and edited by the members as guest editors of the issue. The main...
Article
For the accurate prediction of equilibrium distribution ratios of rare earth metals during solvent extraction under non-ideal conditions, the extraction equilibria of yttrium (III) and europium (III) from the hydrochloric acid solutions with P507 in Shellsol D70 were studied. A chemically-based model was established and the extraction equilibrium c...
Article
A solvent impregnated resin (SIR) containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (EHPNA) as the extractant was tested for zinc removal from aqueous solutions, including the real electroless nickel plating bath employed for an aluminum alloy substrate, in order to extend the bath life. The SIR effectively and selectively adsorbed zin...
Article
This review describes the knowledge required for the development of new extractants for the platinum group metals (PGMs), along with the properties of the conventional and new PGM extractants. Understanding the extraction mechanism of the PGMs is absolutely essential for accelerating the development of new extractants. The structural information of...
Article
A new process for solar grade silicon production by molten salt electrolysis has been proposed and its feasibility discussed. This process consists of an electrolysis step of SiO(2) dissolved in a fluoride melt using an aluminum-silicon liquid alloy cathode and a precipitation step of silicon from the liquid alloy. According to the calculation base...
Article
In the present study, generation of iodine by an electrolytic oxidation from solutions containing iodide ions was investigated in order to develop a recycling process of gold using iodine-iodide solutions. In an anodic polarization curve, the current began to rise at an anodic potential of around 0.5 V vs. SHE, and solution near anode surface becam...
Article
The equilibrium distribution ratios of nickel(II) ion between LIX84I (active component 2-hydroxy-5-nonylacetophenone oxime (HNAPO)), dissolved in a non-polar diluent and 3kmolm−3 ammonium nitrate solution are measured in the pH range 2–10 at 298K. The effect of pH on the distribution ratio of nickel is analyzed based on the extraction equilibrium m...
Article
Demand is growing for the recovery of nickel from spent electroless nickel plating baths (spent bath). The present authors have been studying the application of solvent extraction to this problem, and their findings are outlined in this review. On the basis of batch extraction experiments, a recycling process was established consisting of two steps...
Article
A new process is proposed for separation and recovery of rare earth metals from wastes. This process utilizes molten salt electrolysis and an alloy diaphragm. The diaphragm functions as a bipolar electrode and enables selective permeation of rare earth ions via the following steps: (a) Rare earth ions are produced by either anodic dissolution of wa...
Article
In view of the importance of solvent extraction of rare earth metals with the acidic organophosphorous reagent, the development of a chemically based model applicable to high concentration is desired. In the present study, the equilibrium distribution of dysprosium(III) between an aqueous nitric acid solution and 2-ethylhexylphosphonic acid mono-2-...
Article
The first effective extractant capable of the selective recovery of rhodium3+ from hydrochloric acid solution, N-n-hexyl-bis(N-methyl-N-n-octylethylamide)amine (HBMOEAA), has been developed.
Article
It is urgent to develop an effective technique to treat the large amount of spent electroless nickel plating bath and recycle the high concentration nickel. In our previous study, high recycling efficiency of nickel from the model spent bath was obtained by continuous solvent extraction with 2-hydroxy-5-nonylacetophenone oxime (LIX84I) as the extra...
Article
The treatment of spent electroless nickel plating baths has attracted much attention from the standpoints of environmental protection and nickel recycling. In order to design a nickel recovery process from the spent baths, the continuous extraction and stripping of nickel in the spent baths were carried out using a mixer-settler extractor. 2-Hydrox...
Article
The extractability of Pd(II) using N,N,N′,N′-tetra-n-octyl-thiodiglycolamide (TOTDGA) diluted with a mixed solution of n-dodecane and 2-ethylhexanol and the durability of TOTDGA against a strong acid solution (0.75 M HNO3–2.25 M HCl) were investigated by solvent extraction and FT-IR measurements, then compared to those using the conventional extrac...
Article
Techniques for the removal of lead have been studied in order to develop a hydrometallurgical copper recycling process consisting of copper leaching from wastes using an ammoniacal chloride solution and subsequent copper electrowinning. The solubility of Pb(II) in the ammoniacal chloride solution increased with ammonia concentration; this was attri...
Article
Flow-through electrolysis for copper electrowinning from cuprous ammine complex was studied in order to develop a hydrometallurgical copper recycling process using an ammoniacal chloride solution, focusing on the anodic oxidation of cuprous to cupric ammine complexes. The current efficiency of this anodic oxidation was 96% at a current density of 2...
Article
The separation of precious metals in a hydrochloric acid solution using a solvent impregnated fiber (SIF) was investigated. N-disubstituted amide compounds and kapok fibers were used as the separation reagents and the impregnation support, respectively. We synthesized N,N-di-n-octyl-lauramide (DOLA), N,N′-dimethyl-N,N′-di-n-octyl-thiodiglycolamide...
Article
In order to develop an energy-saving copper recycling process from wastes, electrochemical measurements were conducted in ammoniacal alkaline solutions containing Cu(I) ions and an ammonium salt of sulfate, chloride or nitrate. The results of each system were then compared. The polarization measurements suggested that the voltage required for the e...
Article
The behavior of impurity elements during a copper recovery process from waste printed circuit board (PCB) using ammonia–ammonium sulfate and chloride systems are examined and the performance of these two systems are compared. Leaching of PCB was carried out by solutions containing copper(II) ammine complexes as the oxidizing agent. The copper was s...
Article
Full-text available
The extraction and structural properties of rhodium complexes with stannous chloride using N,N‐dioctyl hexanamide (DOHA) were investigated by solvent extraction and Rh K‐edge X‐ray absorption fine structure (XAFS) spectroscopy. In the absence of Sn(II), Rh was hardly extracted from a 1 M HCl solution. However, the Rh extraction was enhanced with an...