Optimization of Electric Field Assisted Mining Process Applied to Rare Earths in Soils

The extraction of rare earths has been studied worldwide, however some of these processes have a high cost and can cause negative environmental impacts. In order to mine these species from the soil, Electric Field Assisted Mining arises as an alternative to conventional mining processes. Therefore, the experimental parameters can be improved to obtain better results in the extraction of these species. The aim of this paper is to propose the optimization of the Electric Field Assisted Mining process of yttrium, to obtain the optimal experimental configuration to be applied in real soils. An optimization problem was defined to obtain the maximum extraction mass of yttrium ion (Y3+), considering the limitation for the quantity of electric current density. A hybrid optimization technique was used, based on the sequential application of genetic algorithms and non-linear programming. Different optimal process configurations were obtained, considering distinct limits for the electric current density. The best experimental configuration resulted in 0.5386 V cm−1 electric field strength and 0.10 mol L−1 electrolyte concentration. This condition was reproduced in real soil, which obtained a Y3+ electromining efficiency of 41.48%. The results showed that this technique is promising for the extraction of rare earth in real soils.

Enhancement of yttrium ion on the properties of L-histidine nitrate single crystal for frequency conversion applications

Nonlinear optical single crystals of L-histidine nitrate (LHN) as well as 0.05 mol % Y2+ doped LHN and 0.10 mol % Y2+ doped LHN were successfully grown by slow evaporation technique at room temperature. The lower cutoff wavelength and transmittance were 339 nm, 343 nm, 347 nm and 84 %, 86 % and 87 % for LHN, 0.05 mol % and 0.10 mol % yttrium doped LHN, respectively. Powder XRD studies revealed that the grown materials belong to an orthorhombic system with the space group P212121. FT-IR peak at 534 cm−1 due to yttrium coordinated with oxygen was observed. The EDAX analysis confirmed the presence of such elements as C, N, O and Y in the grown materials. High intensity PL emission peak was obtained at 420 nm.