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The article presents the results of investigations into the effectiveness of precipitating rare earth elements (REEs) from mine waters using solutions of alkalinizing reagents (NaOH, Ca(OH)2, Na2CO3), sulphur-containing compounds (sodium trithiocarbonate, sodium trimercapto-s-triazine, sodium dimethyldithiocarbamate) and oxalic acid. The investigations were conducted in two stages. In the first stage, based on initial tests, after REEs precipitation, a compound selected from the alkalinizing reagents group (NaOH) was used, taking into account its efficacy, the amount of sediments formed and their physico-chemical properties, beneficial from the point of view of further treatment. In the second stage the sediments precipitated with NaOH were digested in a mixture of acids and REEs were selectively precipitated with oxalic acid. The efficiency of the investigated process was thoroughly evaluated, taking into consideration the initial concentration of REEs in the mine water used in research and the final concentration of REEs in the obtained sediment, after using oxalic acid as a selective precipitating reagent. The research results confirmed the possibility of obtaining initial REEs concentrates from AMD in the precipitation process using selected reagents. The effectiveness of REEs recovery from selected AMDs achieved as a result of the conducted works was more than 95%. [ABSTRACT FROM AUTHOR]

In recent years we have observed a rapid increase in the demand for rare earth elements (REEs), related to industry intensive development in the field of new technologies. The biggest producer of REEs is China, which provides global markets with more than 83% of the whole amount of rare earth elements. It is worth mentioning that China has access to rich deposits of REEs, accounting for ca 37% of these metals resources available all over the world. For this reason, alternative possibilities to obtain rare earth elements are becoming increasingly important. In the work the potential and forms of rare earth elements (REEs) occurrence in acid mine drainage (AMD), produced as a result of hard coal mining in the Upper Silesian Basin have been presented. The results of initial investigations into the contents of rare earth elements in acid waters from the drainage of an active hard coal waste tip located in Libiąż, in the south of Poland, have been discussed. Field measurements of selected parameters of tip leachates (temperature, pH, electrolytic specific conductivity, redox potential, dissolved oxygen) have been taken. Rare earth elements were determined by inductively coupled plasma mass spectrometry (ICP-MS). The conducted investigations have demonstrated that acid waters flowing from hard coal waste storage sites are much richer in REEs compared to waters which fill old excavations resulting from other minerals mining. In the work the possibility of using acid mine drainage to obtain REEs has been demonstrated. Factors influencing the differentiation of rare earth elements contents in acid waters in view of the possibility to reuse them have been discussed. Attention was drawn to the phenomenon of environmental pollution in mining areas caused by acid mine drainage leachates, also in the context of REEs release into the environment. [ABSTRACT FROM AUTHOR]

According to data reported in the EU report, critical raw materials include 20 raw materials, including rare earth heavy metals (Gd-Lu and Y) and rare earth light metals (La-Eu). Thus, rare earth metals include lanthanides of atomic number 58-71 and scandiums with atomic numbers Sc -21, Y -39 and La -57, respectively. Rare earth metals are used in many modern, innovative techniques such as optics, nuclear technology, production of permanent magnets that are part of discs for computers and automotive hybrid motors, thermal coatings for jet engines, catalysts, etc. The paper analyzes the process of recovery of rare earth metals from fly ash from Polish power plants with coal combustion in pulverized coal boilers. It has been confirmed that the total rare earth content in fly ashes from Polish power plants is between 250-450 ppm and rarely reaches 500 ppm. It has been found that elements with odd atomic numbers are less common in the test material than with even atomic numbers. Research on the hydrometallurgical recovery of rare earth metals from fly ash using sulfuric acid as a leaching agent was conducted. The effect of sulfuric acid concentration and some kinetic parameters on the leaching rate of individual rare earths was determined. The possibility of obtaining rare earth metals from ashes in Polish conditions was assessed. [ABSTRACT FROM AUTHOR]

Currently applied groundwater protection against penetration of pollutants from landfills are membranes that isolate the layer of stored waste from the substrate. As the material most commonly used are materials such as loam and natural clay or composite materials, such as plastic films or asphalt. Also there are known methods of using waste materials such as fly ash, as well as silicate-ash composites for the manufacture of seals in civil and hydraulic engineering. Literature also contains descriptions of the research related to the possible use of dolomite from ore deposits as a material for the production of active barriers on industrial waste landfills. In the article there is analyzed a process of sorption of zinc ions by dolomites of grain size 0-2 mm, derived from the Triassic and Devonian deposits of one of the dolomite mines in Poland. Based on the research, it has been found that the effectiveness of the groundwater protection process against pollutions and the elimination of heavy metals from leachate effluents at landfill sites where dolomite-based geomembranes from Triassic and Devonian deposits are applied is associated both with a decrease in the water permeability of the substrate and in the sorption capacity of sealing material. It has been shown that the water permeability index of the Triassic and Devonian dolomite is similar to the values of, for example, certain types of fly ash used as geomembrane in landfills. The studies of dolomite from the Triassic and Devonian deposits have shown:. • the effectiveness of this material for the construction of protective layers for hazardous waste landfills. • high sorption capacity of the selected dolomite for a wide range of concentrations of sorbate used in the form of zinc ion solutions. • high zinc binding stability of dolomites. The research has led to the development of a concept for the use of dolomite from the Triassic and Devonian deposits for the construction of geomembranes in industrial waste landfills, where there is a risk for groundwater from effluents containing heavy metals. [ABSTRACT FROM AUTHOR]