## 1 Introduction  
Fluorine belongs to earth elements present in high quantities with approximately 950 mg F kg\({}^{-1}\) of the earth's crust (13 th most abundant element) [1, 2]. In nature, this element mainly occurs in deposits of fluorite, cryolite, topaz, and fluorapatite. The world resources of fluorspar are estimated at approximately 230 million tons, with China, Mongolia, Mexico, and South Africa having almost half of the resources of this mineral [3]. No economically significant fluorspar deposits have been identified in Poland and therefore it has never been mined in our country. Insignificant amounts of synthetic fluorspar are obtained by Chemical Plant Siarkopol Tarnobrzeg Sp. z o.o. (Tarnobrzeg, Poland) during the production of phosphoric acid from phosphorites. The total Polish demand for this mineral is provided by importation, primarily from Mexico, Germany, and the Czech Republic. When it comes to phosphoric deposits, there is currently no mining of this deposit in Poland, and the entire demand for this raw material is covered by imports from other countries, primarily from Algeria, Morocco, Egypt, and Syria. The national consumption of phosphate rock is determined by the needs of agriculture and limited by the production capacity of large fertilizer industry plants, which include: Chemical Plant Police S.A., GZNF Fosfory Sp. z o.o. (AZOTY Group), Luvena S.A., Chemical Plant Siarkopol TarnobrzegSp. z o.o., Fosfan S.A. There are a number of environmental problems associated with the processing of phosphate deposits. This applies especially to the so-called phosphogypsum, generated as waste in huge amounts in the wet production of phosphoric acid (Chemical Plant Police S.A., GZNF Fosfory Sp. z o.o. (AZOTY Group), and Chemical Plant Wizow). Phosphogypsum contains significant amounts of fluorine, uranium, and a number of other trace elements that should be recovered or neutralized, otherwise they pose a significant threat to the natural environment [4]. [PERSON] et al. [5] found during their research that phosphogypsum, in addition to gypsum and basanite (\(\
eg\)95%), contains fluorine (0.5-1.5%), orthophosphates, phosphates, sulphates, and elements such as Cd, Cr, Pb, Hg, As, B, Cu, Mg, Mo, Sc, Hf, Zn, Sr, and Ba, as well as elements from the lanthanide family (Ce, Eu, La, Lu, Lu, Nd, Sm, Tb, and Yb) and compounds of radioactive elements such as U, Th, Ra, and Po. In order to imagine the scale of the problem, it is worth providing the example of one of the largest heaps of phosphogypsum in Poland, located near the village of Wislinka near Gdansk. The landfill covers an area of 36 ha, where over 16 million tons of phosphogypsum have been deposited over 30 years, and the height of the heap reaches 40 m. After the end of the operation, attempts were made to reclaim the heap by covering it with dry sewage sludge and then sowing appropriate plant species to protect the surface against erosion [6]. The impact of such a heap on the natural environment is very unfavorable, mainly due to the constant dusting from the surface of the heap, the emissions released into the atmosphere of all types of toxic compounds including fluoride, and their penetration into the deeper layers of soil, surface, and ground waters. Reclamation of this type of landfill is very problematic, primarily due to the unfavorable physicochemical properties of the soil, the complete absence of organic matter, and a very low reaction. The selection of appropriate plant species also poses a serious problem and is usually performed via the trial method [7]. In soil, fluorine binds to other soil native elements, such as aluminum (Al), calcium (Ca), iron (Fe), or siltstone minerals, forming stable fluorine compounds. Factors that considerably alter the mobility of fluorine are the soil reaction and the presence of aluminum and calcium complexes in the soil. [PERSON] et al.