**Acknowledgements**

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

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

A mixture of fluorescent lamps of a different kind was processed for the recovery of REE

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

Due to the depletion of natural resources, increased environmental pollution, and dependence on suppliers from China, the recovery of valuable metals from WEEE is currently of great importance. Broadly understood economic development and new technologies in the electrical and electronic market are beneficial for people, but they also harm the surrounding environment and, consequently, all of us. Therefore, the intensively developing industry of recovery of metals from secondary sources has many positive aspects such as less hazardous

Despite the small amount of recycling of REE, the worldwide production of these metals currently exists at about 130,000 metric tonnes of REO equivalent content per year, with the 2014 REE market worth about US\$2051 million [64]. A large amount of REE is used in the production of catalysts, glass, lighting, and in the metallurgy industry, 59% in 2011, and the remain-

Development of modern technologies both in the field of electronics and green motorization is heavily dependent on rare earth elements. Also in Poland, the constantly growing consumption of REE is observed. Poland does not actually have its own REE natural deposits. The demand for these metals is mainly covered by import from China, West Europe, and USA. Alternative sources can be rich hard coal resources and a large share of fossil fuels in energy production. No wider studies on the occurrence of REE have been conducted in the country so far, for example, for the assessment of the hard coal deposits and power fly ashes as reasonable sources of lanthanides. Fragmentary data not allow to determine the full

, or a reduction in the use of natural

at 80°C, about 90% for Eu, and 95% for Y [62].

mixer-settler systems of three extraction and four stripping stages.

**8. Summary: current status and perspectives**

waste, reduction of greenhouse gas emissions and CO2

volume of REE in Polish hard coal.

resources and thus reducing the destruction of the natural environment.

ing 41% in new increasing markets such as magnets, batteries, and ceramics [64].

in a pilot plant scale [59].

especially Y and Eu [63].

or 3 M HNO3

20 Lanthanides

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 international project cofinanced IAEA Research Contract No: 18542.
