**6. Separation of REE from waste and products of phosphate fertilizer industry**

The process of the recovery of REE from phosphogypsum has been studied in Poland for over 30 years. As a leaching solution, a concentrated sulfuric acid, nitric acid, or their mixture have been applied. For separation of rare earth elements, different methods have been used: precipitation and extraction in liquid-liquid systems with the participation of an organic phase as well as crystallization methods, among others [43, 44]. Results of this work confirmed higher efficiency of leaching lanthanides from phosphogypsum by the application of nitric acid (c.a. 90%) than sulfuric acid (c.a. 60%). However, in the case of using nitric acid, an additional waste threatening the environment is generated.

Polish uranium ores are black shale and sandstone-type deposits [34, 35]. Uranium is usually accompanied by other valuable metals, among them REE [36]. These metals could be recovered at the same time as uranium, to improve the economy of processing of low-grade uranium ores predominated in the country. The content of lanthanum in Polish ores is 31–62 ppm in dictyonema shales and 4–53 pm in Triassic sandstones. The studies performed in the scope of national projects have shown 66% efficiencies of leaching of La from dioctynemic shales by 10% H<sup>2</sup>

at 80°C [36]. The leaching under elevated pressure (2, 3, 5, 7 bar) did not improve the efficiencies, however shortened the time of process from 8 to 2 hours. Zakrzewska-Koltuniewicz et al. developed the second-order regression models to predict the leaching efficiencies of valuable chemical elements. They carried out the statistically designed experiments to investigate the recovery of U, V, and Mo chemical elements and representative lanthanides like La and Yb from low-grade uranium ore using sulfuric acid as a leaching reagent [37]. Lanthanum can also be extracted from sandstones with high efficiency (80%) at temperature 60°C with 10% HCl [38]. Very interesting, the novel method used for processing Polish uranium ores was a leaching in the membrane contactor with helical flow equipped with tubular metallic membrane. In this process, lanthanum was co-extracted with uranium from dictyonema shales with 78% of efficiency [39]. The process was carried out at ambient temperature, and the yield of leaching was higher than obtained in the stationary reactor with heating and mixing. The additional advantage of using the membrane contactor is a possibility of conducting two processes:

The post-leaching solution obtained from the separation of solid residue from liquid is a mixture of various metal ions. The further purification and separation of metals can be achieved by solvent extraction followed by stripping to aqueous phase or by ion exchange. By using solvent extraction, we cannot avoid some of the problems associated with this process. A third phase between aqueous and organic phases is often formed in solvent extraction process. It is related to the solubility of the metal-extractant complex in the organic solution. The formation of the third phase may cause many difficulties; first of all, it leads to organic solvent loss. The minimization of the formation of the third phase can be achieved by addition of a modifier to the organic phase [40] or by application of membrane contactors, a multistage mixer-settler

Ion exchange proved also itself as an effective separation method of metals from water solutions. Danko et al. proposed to use Dowex 1X10 and Dowex 50WX4 for valuable metals extraction from pregnant leach liquors from extraction of Polish ore. The recovery of lanthanides

**6. Separation of REE from waste and products of phosphate fertilizer** 

The process of the recovery of REE from phosphogypsum has been studied in Poland for over 30 years. As a leaching solution, a concentrated sulfuric acid, nitric acid, or their mixture have been applied. For separation of rare earth elements, different methods have been

arrangement with concurrent flow of two phases—aqueous and organic [41].

leaching and solid-liquid separation in one apparatus.

was 99% [42].

16 Lanthanides

**industry**

SO4

The possibility of recovery of REE from phosphogypsum stored in Wizów heap with simultaneous recovery of P2 O5 and production of anhydrite cement was also a subject of work [14]. The technology was examined at laboratory scale by the processing of 1 Mg/h of phosphogypsum. The technological flowsheet consisted of three steps: (i) leaching of lanthanide from the phosphogypsum using sulfuric acid at a concentration of 15%, (ii) crystallization of the rare earth concentrate (containing up to 25% Ln2 O3 ) from the leach solution, and (iii) recrystallization of gypsum. In this way, insoluble high-quality anhydrite, phosphoric acid, and concentrate of rare earths concentrate containing more than 90% of oxides were products of the process. The composition of the rare earth concentrate is presented in **Table 3**.

The leaching of valuable metals from phosphogypsum stored in Wiślinka heap was also studied. The experiments were performed in laboratory scale. Lanthanum and other REEs were recovered with high efficiencies (**Figure 4**). Initially, the phosphogypsum was treated with 30% NaOH at 60°C, and then the solid residue was leached with 10% HCl at 60°C [12, 45].

Zielinski et al. studied the recovery of lanthanides from Kola apatite used for the phosphoric acid production in Polish phosphoric fertilizer factory [46]. It was found that a stage of the hydration of hemihydrate provides the best conditions for the recovery of lanthanides. In this stage for the removal of lanthanides, a solvent extraction has been applied and consequently a precipitation-stripping process for the removal of lanthanides from the solvent has been employed. As a result, a concentrate enriched with lanthanides has been obtained in which lanthanides were recovered with an efficiency of 80–85%. The similar results were obtained by the El-Didamony et al. in the studies of reduction in the concentration of radionuclides in phosphogypsum by using suitable organic extractants. This process was accompanied by reduction in the concentration of REE up to 80.1% [47–49].


**Table 3.** The composition of the concentrate of REO [14]

materials, carbon, organic binders, organic solvents, salts, additives, valuable metals, etc. Very important steps for the hydrometallurgical recovery of metals from a wide range of WEEE are

Perspective of Obtaining Rare Earth Elements in Poland http://dx.doi.org/10.5772/intechopen.80743 19

Usually, a recycling of different types of waste electrical and electronic equipment is very complex because of the complexity of the material; the content of metals, for example, lowgrade or high-grade material; the solubility and/or thermal stability; etc. Recovery of REE from WEEE using pyrometallurgical treatment is energy demanding, and often, the final products that are obtained require another processing to get pure compounds of the material [53]*.* As an alternative to pyrometallurgical processes, the metallurgical industry has been examining for hydrometallurgical treatment, due to some benefits related to hydrometallur-

Rare earth elements are used in the production of metal alloys (25%), catalysts (16%), permanent magnets (23%), polishing materials (11%), glass (7%), and materials containing phosphors (7%). The applications of these metals should provide the opportunities for strategic recycling and material recovery after their use. Recycling of spent fluorescent lamps can be a useful secondary source of Y, Eu, and Tb, and recycling of permanent magnets, which are used in water and wind energy as well as in HEV and EV vehicles, can become an important

The amount of REE depends significantly on the type of waste electrical and electronic equipment (WEEE) and can range from several hundred ppm to several dozen percents. Particularly

Usually, the processes of obtaining rare earth from permanent magnets are preceded by pretreatment, which includes such operations as mechanical disassembly of waste, physical separation, grinding to the proper grain size, thermal treatment, pyrometallurgy, hydrometallurgy, etc. Methods are adequate to the particular type of waste electrical and electronic equipment. The basic technologies include such unit processes as rare earth recovery through thermal or hydrometallurgical processing. For example, the recovery process of the neodym-

magnesium, the separation of the liquid phase from the solid phase, and the evaporation of liquid magnesium. After these operations, the obtained final product contains about 96% of

The recycling and separation processes of Nd and Dy from permanent magnet scrap has been also studied by a hydrometallurgical method using liquid emulsion membranes in an integrated process [58]. In this method, the removal of ions is the result of processes taking place in one apparatus, that is, the production of liquid emulsion membranes and extraction. The extraction process involves the steps of transporting metal ions of Nd and Dy through the membrane phase of the emulsion to the phase of internal droplets, where they are separated

Nickel-metal hydride batteries (NiMH) that are used in the production of hybrid vehicles are another secondary source of valuable rare earth elements. The typical NiMH car batteries

B magnet scrap consists of the extraction of neodymium with liquid

. Some magnets of this type include additionally about 5% of Dy [1].

B (about 24% of Nd)

gical processing, mainly for low-grade and chemically difficult streams [53].

source of secondary acquisition of Nd, Pr, Dy, and Tb [54–56].

or Sm2

Nd [57].

Co5

ium from the Fe14Nd2

by the extraction.

rich in rare earth elements are wasted permanent magnets of type Fe14Nd2

mechanical pretreatment and dismantling.

**Figure 4.** The efficiencies of leaching REE from phosphogypsum stored in Wislinka heap, Poland.

The possibilities of separation of rare earth elements from phosphoric acid solution have been also investigated [50]. A strongly basic ion-exchange resin with quaternary ammonium functional groups (Dowex 1) has been used for this purpose. The effect of temperature and resin cross-linking on the column performance and the ion-exchange reactions of phosphate complexes of several rare earths were determined. It was found that the resolution increases with increase of temperature, and the best separation was obtained at temperature of 85°C.

A separation of lanthanides form phosphoric acid through a crystallization process has been also investigated [51]. The effect of temperature and H<sup>3</sup> PO4 concentration on lanthanide solubility was tested. As a result of the experiments, highly crystalline solids of lanthanide phosphates were obtained.

#### **7. Recovery of REE from WEEE**

A complete strategy of recycling of waste electrical and electronic equipment consists of policies of waste management, research and development in new methods of processing, and challenges in elaboration of new technologies. For many countries, mainly those having limited access to mineral resources of REE, the development and improvement of the recycling processes of valuable metals from WEEE are significant aspects from the economic and environmental point of view. In Poland, obtaining a concentrate of REE from the discussed secondary raw material on an industrial scale is currently an economic issue. Unfortunately, about 70% of collected WEEE waste is processed in China [52].

In general, waste electrical and electronic equipment (WEEE) is a mixture of different materials and can consist of steel, printed circuit boards, batteries, permanent magnets, hard drives, plastic, aluminum foils, phosphors, photovoltaic materials, cables, separators, active materials, carbon, organic binders, organic solvents, salts, additives, valuable metals, etc. Very important steps for the hydrometallurgical recovery of metals from a wide range of WEEE are mechanical pretreatment and dismantling.

Usually, a recycling of different types of waste electrical and electronic equipment is very complex because of the complexity of the material; the content of metals, for example, lowgrade or high-grade material; the solubility and/or thermal stability; etc. Recovery of REE from WEEE using pyrometallurgical treatment is energy demanding, and often, the final products that are obtained require another processing to get pure compounds of the material [53]*.* As an alternative to pyrometallurgical processes, the metallurgical industry has been examining for hydrometallurgical treatment, due to some benefits related to hydrometallurgical processing, mainly for low-grade and chemically difficult streams [53].

Rare earth elements are used in the production of metal alloys (25%), catalysts (16%), permanent magnets (23%), polishing materials (11%), glass (7%), and materials containing phosphors (7%). The applications of these metals should provide the opportunities for strategic recycling and material recovery after their use. Recycling of spent fluorescent lamps can be a useful secondary source of Y, Eu, and Tb, and recycling of permanent magnets, which are used in water and wind energy as well as in HEV and EV vehicles, can become an important source of secondary acquisition of Nd, Pr, Dy, and Tb [54–56].

The possibilities of separation of rare earth elements from phosphoric acid solution have been also investigated [50]. A strongly basic ion-exchange resin with quaternary ammonium functional groups (Dowex 1) has been used for this purpose. The effect of temperature and resin cross-linking on the column performance and the ion-exchange reactions of phosphate complexes of several rare earths were determined. It was found that the resolution increases with increase of temperature, and the best separation was obtained at temperature of 85°C.

**Figure 4.** The efficiencies of leaching REE from phosphogypsum stored in Wislinka heap, Poland.

A separation of lanthanides form phosphoric acid through a crystallization process has been

solubility was tested. As a result of the experiments, highly crystalline solids of lanthanide

A complete strategy of recycling of waste electrical and electronic equipment consists of policies of waste management, research and development in new methods of processing, and challenges in elaboration of new technologies. For many countries, mainly those having limited access to mineral resources of REE, the development and improvement of the recycling processes of valuable metals from WEEE are significant aspects from the economic and environmental point of view. In Poland, obtaining a concentrate of REE from the discussed secondary raw material on an industrial scale is currently an economic issue. Unfortunately,

In general, waste electrical and electronic equipment (WEEE) is a mixture of different materials and can consist of steel, printed circuit boards, batteries, permanent magnets, hard drives, plastic, aluminum foils, phosphors, photovoltaic materials, cables, separators, active

PO4

concentration on lanthanide

also investigated [51]. The effect of temperature and H<sup>3</sup>

about 70% of collected WEEE waste is processed in China [52].

phosphates were obtained.

18 Lanthanides

**7. Recovery of REE from WEEE**

The amount of REE depends significantly on the type of waste electrical and electronic equipment (WEEE) and can range from several hundred ppm to several dozen percents. Particularly rich in rare earth elements are wasted permanent magnets of type Fe14Nd2 B (about 24% of Nd) or Sm2 Co5 . Some magnets of this type include additionally about 5% of Dy [1].

Usually, the processes of obtaining rare earth from permanent magnets are preceded by pretreatment, which includes such operations as mechanical disassembly of waste, physical separation, grinding to the proper grain size, thermal treatment, pyrometallurgy, hydrometallurgy, etc. Methods are adequate to the particular type of waste electrical and electronic equipment. The basic technologies include such unit processes as rare earth recovery through thermal or hydrometallurgical processing. For example, the recovery process of the neodymium from the Fe14Nd2 B magnet scrap consists of the extraction of neodymium with liquid magnesium, the separation of the liquid phase from the solid phase, and the evaporation of liquid magnesium. After these operations, the obtained final product contains about 96% of Nd [57].

The recycling and separation processes of Nd and Dy from permanent magnet scrap has been also studied by a hydrometallurgical method using liquid emulsion membranes in an integrated process [58]. In this method, the removal of ions is the result of processes taking place in one apparatus, that is, the production of liquid emulsion membranes and extraction. The extraction process involves the steps of transporting metal ions of Nd and Dy through the membrane phase of the emulsion to the phase of internal droplets, where they are separated by the extraction.

Nickel-metal hydride batteries (NiMH) that are used in the production of hybrid vehicles are another secondary source of valuable rare earth elements. The typical NiMH car batteries contain approximately 3 kg of REE, 11 kg of nickel, and 1.5 kg of cobalt. A hydrometallurgical technology has been carried out for the recovery of valuable metals from spent car NiMH batteries in a continuous countercurrent solvent extraction process using a mixer-settler system in a pilot plant scale [59].

A prospective direction in obtaining REE from domestic resources can be processing of WEEE. In recent years the interest of small entrepreneurs in this subject is noticeable. Many small companies have been established, dealing primarily with the collection and segregation of electric and electronic waste materials. With the help of national assets and money from EU structural funds, many innovative projects in the field of metal recycling are carried out. Innovative REE recovery projects can meet the expectations of satisfying the demand for these

Perspective of Obtaining Rare Earth Elements in Poland http://dx.doi.org/10.5772/intechopen.80743 21

The studies were supported by the Ministry of Science and Higher Education, Poland, financial resources for science in the years 2017–2019 granted for the implementation of the inter-

[1] Jarosiński A. Możliwości pozyskiwania metali ziem rzadkich w Polsce. Zeszyty Naukowe Instytutu Gospodarki Surowcami Mineralnymi i Energią Polskiej Akademii Nauk.

[2] Gronek S, Łęczycki K. Rare earth elements and their importance for economy and safety. Aviation Advances and Maintenance. 2017;**40**:129-150. DOI: 10.1515/afit-2017-0011 [3] Armbrustmacher TJ, Modreski PJ. Petrology and mineralogy of alkaline rocks from the Elk massif, northeastern Poland. Denver, USA: U.S. Department of Interior, U.S.

[4] Mikulski SZ, Kramarska R, Zeliński G. Rare earth elements pilot studies of the Baltic marine sands enriched in heavy minerals. Mineral Resource Management. 2016;**32**:5-28.

[5] Mochnacka K, Banaś M. Occurrence and genetic relationships of uranium and thorium mineralization in the Karkonqsze-Izera block (the Sudety MTS, SW Poland). Annales

Katarzyna Kiegiel\*, Agnieszka Miśkiewicz, Irena Herdzik-Koniecko, Dorota Gajda

valuable, irreplaceable metals in today's life.

and Grażyna Zakrzewska-Kołtuniewicz

2016;**92**:75-88 (in Polish)

Geological Survey; 1994

DOI: 10.1515/gospo-2016-0036

Societcitis Geologorum Poloniae. 2000;**70**:137-150

\*Address all correspondence to: k.kiegiel@ichtj.waw.pl

Institute of Nuclear Chemistry and Technology, Warsaw, Poland

national project cofinanced IAEA Research Contract No: 18542.

**Acknowledgements**

**Author details**

**References**

At the Institute of Mechanised Construction and Rock Mining, Warsaw, Poland, a method for recovery of yttrium and europium from used phosphors was developed, that is the subject of the patent PL-200095, 2008 [60, 61]*.* Acidic leaching, hydrolytic precipitation, and/or solvent extraction methods have been used in the recovery of Eu and Y from waste fluorescent lamps containing ~0.3% Eu and 7% Y. The best results of leaching efficiency were reached in 3 M HCl or 3 M HNO3 at 80°C, about 90% for Eu, and 95% for Y [62].

A mixture of fluorescent lamps of a different kind was processed for the recovery of REE especially Y and Eu [63].

The high efficiency of oxide containing 99.96% REE (94.61% yttrium, 5.09% europium, and 0.26% of the other REE) was reached in solution with 35 vol% Cyanex 923 in kerosene using mixer-settler systems of three extraction and four stripping stages.
