• Vol 11, No 3 (2020)
  • Chemical Engineering

Extraction Development for the Separation of Gadolinium from Yttrium and Dysprosium Concentrate in Nitric Acid using Cyanex 572

Kris Tri Basuki, Alfiyatur Rohmaniyyah, Wahyu Rachmi Pusparini, Andri Saputra

Corresponding email: kristri_basuki@batan.go.id

Cite this article as:
Basuki, K.T., Rohmaniyyah, A., Pusparini, W.R., Saputra, A. 2020. Extraction Development for the Separation of Gadolinium from Yttrium and Dysprosium Concentrate in Nitric Acid using Cyanex 572. International Journal of Technology. Volume 11(3), pp. 450-460

Kris Tri Basuki Department of Nuclear Chemical Engineering, Polytechnic Institute of Nuclear Technology (STTN), Jl. Babarsari, Yogyakarta 55821, Indonesia
Alfiyatur Rohmaniyyah Department of Nuclear Chemical Engineering, Polytechnic Institute of Nuclear Technology (STTN), Jl. Babarsari, Yogyakarta 55821, Indonesia
Wahyu Rachmi Pusparini Accelerator Science and Technology Center (PSTA) - National Nuclear Energy Agency (BATAN), Jl. Babarsari, Yogyakarta 55821, Indonesia
Andri Saputra Department of Nuclear Chemical Engineering, Polytechnic Institute of Nuclear Technology (STTN), Jl. Babarsari, Yogyakarta 55821, Indonesia
Email to Corresponding Author


Xenotime sand, a byproduct of the tin mining process of PT Timah, is one of the potential gadolinium (Gd) resources. Because of similarities in their physical and chemical properties, it is difficult to separate and purify Gd from rare earth elements (REEs) in xenotime sand (i.e., yttrium and dysprosium). In the present work, Gd was separated through an extraction process using Cyanex 572. The extraction feed solution was prepared by digesting the REE oxalate in NaOH to obtain REE(OH)3. The effects of the extraction parameters (i.e., stirring time and rate, feed pH and concentration, and Cyanex 572 concentration) were examined via a batch experiment. The optimum results of Gd separation from yttrium concentrate were achieved when the process conditions included a 250-rpm stirring rate for 30 minutes, a 150×103-ppm feed concentration at pH 3, and a 30% Cyanex 572 concentration. These conditions gave distribution coefficient results for Y, Gd, and Dy of about 0.031, 0.827, and 1.060, respectively; separation factors of Gd-Y and Gd-Dy of about 26.482 and 0.780, respectively; and extraction efficiencies for Y, Gd, and Dy of about 3.119%, 46.627%, and 53.007%, respectively.

Cyanex 572; Dysprosium; Extraction; Gadolinium; Separation; Yttrium


Gadolinium (Gd), yttrium (Y), and dysprosium (Dy) are included in a group of 17 chemically similar metallic elements called rare earth elements (REEs). Gd has excellent scintillation properties and a high magnetic moment compared with other REEs. In the nuclear industry, gadolinium oxide is used for radiation-shielding ceramic compositions (Gupta and Krishnamurthy, 2005) and control rods (Jaworski and Gawlowski, 2015) as well as in making optical fibers. Gd is also added to optical glasses for use in electro-optical and magneto-optical systems. Gd (1%) in iron, chromium, and related alloys improves resistance to oxidation and high temperatures (Xu et al., 2014). Y is also an important element used in electrical material (Rahmawati et al., 2015), for example, to increase ionic conductivity (Shakthinathan et al., 2012).

Data from 2014 shows that China is the world’s largest REE deposit, containing about 58% of the total global deposit of 154,135 tons. Meanwhile, the Indonesian REE deposit hypothesis shows a very small amount, about <1% of the total world deposit (Gunradi et al., 2019).  The main minerals containing REEs found in Indonesia are xenotime, monazite, and zircon, associated with cassiterite obtained from alluvial tin mining. Granite, pegmatite, and metamorphic, ultramafic, and alluvial rocks are among the types of rocks that may contain REEs in Indonesia. These REE minerals are concentrated in the Riau Islands, Bangka Belitung, and parts of West Kalimantan (Virdhian and Afrilinda, 2014; Gunradi et al., 2019). Xenotime sand, a byproduct of the tin mining process of PT Timah, is one of the potential gadolinium resources of REEs. It contains rare earth phosphate minerals such as 29.53% Gd, 7.76% Y, and 2.58% Dy (Atmawinata et al., 2014). In Indonesia, xenotime has not been further processed to obtain pure REEs or to obtain its oxides. If Gd, Y, and Dy can be separated from other materials properly, this will increase xenotime’s economic value.

Because of similarities in REEs’ physical and chemical properties, it is difficult to separate and purify Gd from other REEs (other lanthanides). To separate Gd in high purity, it is necessary to find the most efficient and feasible technology (Fisher and Kara, 2016). High-purity REEs like Gd have received considerable attention in recent years due to various industrial applications, limited supply, significant price fluctuations, and market availability (Hasan et al., 2009; Torkaman et al., 2013).

Many methods, such as solvent extraction, fractional crystallization, ion exchange, and chemical precipitation, are used to purify and separate REEs. A well-known method of purification and separation is solvent extraction (Andriayani et al., 2015; Wahab et al., 2016). On an industrial scale, solvent extraction is the most successful method for the extraction and separation of REEs (Wang et al., 2014). The development of new extractants and more efficient extraction techniques is essential for maintaining a stable supply of REEs to meet rapidly increasing demand on a global scale (Tunsu et al., 2016).

Organophosphorus and amine are extractants commonly used to extract REEs in acid solutions. Cytec Industries, Inc., introduced a new extractant, known as Cyanex 572, which belongs to the type of organophosphorus extractant whose active ingredient is a mixture of phosphinic and phosphonic acid with the active group of POOH. This type of extractant is known for its selectivity to certain metals, and one such extractant is used for the separation of metals from heavy REE groups using the liquid-liquid extraction separation method (solvent extraction). Cyanex 572 is specifically designed to extract heavy REEs under the required operating conditions of low acidity (Cytec, 2014). Cyanex 572 has been studied for extracting REEs and Th from waste residues, including ion-absorbed minerals or fluorescent lamps (Tunsu et al., 2016). Cyanex 572 synergized with n-octyl diphenyl phosphate (ODP) has also been studied for extracting Th from leaching solutions of rare earth residues (Zhou et al., 2019). El-Hefny et al. (2018) used Cyanex 572 to separate Y(III) and Dy(III) in hydrochloric and nitric acid solutions.

Gd extraction was studied by Vijayalakshmi et al. (2014) using EHEHPA as a solvent and by Taufan et al. (2008) using DBDTC. Torkaman et al. (2016) also studied Gd extraction using D2EHPA and Cyanex 301. This study proposes to investigate the separation of Gd from xenotime sand by an extraction process using Cyanex 572 solvent in nitric acid solution. Nitric acid has been used to dilute REE(OH)3 or Gd and other elements in REE(OH)3 (Taufan et al., 2008).


Based on the results of the present research, the optimum conditions for the separation of Gd from yttrium concentrate were obtained at a 30-minute stirring time, a 250-rpm stirring rate, a feed concentration of 150×103 ppm with pH 3, and a 30% Cyanex 572 concentration. The distribution coefficient values of Y, Gd, and Dy of about 0.031, 0.827, and 1.060, respectively. The separation factor value of Gd-Y was 26.482, while that of Gd-Dy was 1.5276. The extraction efficiency values of Y, Dy, and Gd were 3.119%, 53.007%, and 46.662%, respectively.


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