Leaching the Unleachable Mineral: Rare Earth Dissolution from Monazite Ore in Condensed Phosphoric Acid

Monazite is a poorly soluble mineral of rare earth phosphate. It is an ore of the rare earths which is difficult to break down; in industry either concentrated sulphuric acid or caustic soda is used to attack finely ground monazite at between 140 °C and 400 °C. In these processes, the rare earths are converted into different solid compounds, undergoing an incomplete conversion. Here we show a new process for a direct and much faster breakdown of monazite by simple dissolution under milder conditions. Condensed phosphoric acid was used to dissolve rare earths (up to 96 g/L) from unground monazite sand from four sources. Greater than 99% of light rare earths dissolved within 30 min at 260 °C. The cooled solution can be diluted to an extent with water to reduce viscosity for analysis or further processing. This method of dissolution avoids the use of strong acids/bases and reduces the risk of dusk exposure from fine grinding of particles.

DyPO4·1.5H2O Microcrystals: Microwave/Ultrasound/ Ultraviolet Light- Assisted Synthesis, Characterization and Formation Mechanism

Background: Researchers have pursued the new synthesis method. As a newly developed method, microwave (MW), ultrasound (US) and ultraviolet light (UV) assisted synthesis has drawn increasing interests. Under the synergistic effect, many materials with new structure, morphology and properties may be found. As an important rare-earth phosphate, DyPO4 was selected and the effect of MW, US and UV on the preparation was investigated. Method: The DyPO4·1.5H2O nanostructures were prepared by MW, US, UV and their combination. Results: Hexagonal DyPO4·1.5H2O microcrystals obtained under MW irradiation were broomstick bundles. Needle-shaped products were formed in the presence of MW and US. Interestingly, the broom-sheaf-like structures can self-assemble into flower-shaped structures upon the irradiation of MW and UV. Whereas, MW/UV/US synergetic heating results in mixed morphologies of flower-like and needle-shaped structures. Conclusion: The growth of DyPO4 nanostructures can be tuned by selecting the combination of heating method of MW, US and UV.

Composition and age of monacite fragments from superior jurassic terrigenous sediments of bazhenov formation foundation (multan area in west siberia)

Bazhenov Formation is regarded as the main oil-bearing stratum mothering nearly all the fields of the Western Siberia Oil-Gas-bearing Megabasin. Presently, it is one of the most studied formations of Siberia and, probably, Eurasia as a whole. While there is an enormous amount of studies devoted to the Bazhenov Formation, there are no detailed mineralogical studies at the modern hardware level. The age and sources of the terrigenous materials of the formation have not been studied as well. We have explored the detrital monazite from the upper-Jurassic terrigenous sediments of the Multan Area at the foundation of the Bazhenov Formation in the central part of Western Siberia, Surgut District. All the detrital rare earth phosphate is of the cerium kind being a monazite-(Се). The mineral is rather dissimilar in respect of its chemical properties, especially, the content of thorium. Some fragments have been subjected to superposed secondary changes. The detrital monazite is rounded to various degrees which is indicative of the various distances from the rare earth phosphate orebody washout. As per the chemical data, most of the monazite has been washed out from the medium and basic rocks (probably subalkaline or alkaline) as well as the sialic rocks (granitoids and associated veins). According to the chemical dating, most of the monazite fragments have been washed out of the very ancient Proterozoic formations and lower-Proterozoic rocks. Terrigenous materials derives probably from the rock assemblages of the eastern and south-eastern fringes of the Western Siberian megabasin such as the Proterozoic Yenisei Ridge or Lower-Proterozoic blocks of the Altay and Sayan Faulting.

High-efficient fabrication of core-shell-shell structured SiO 2 @GdPO 4 :Tb@SiO 2 nanoparticles with improved luminescence

SiO 2 @GdPO 4 :Tb@SiO 2 nanoparticles with core-shell-shell structure were successfully synthesized by a cheap silane coupling agent grafting method at room temperature. This method not only homogeneously coated rare-earth phosphate nanoparticles on the surface of silica spheres but also saved the use of rare-earth resources. The obtained nanoparticles consisted of SiO 2 core with a diameter of approximately 210 nm, GdPO 4 :Tb intermediate shell with thickness of approximately 7 nm, and SiO 2 outer shell with thickness of approximately 20 nm. This unique core-shell-shell structured nanoparticles exhibited strong luminescence properties compared with GdPO 4 :Tb nanoparticles. The core-shell-shell structured nanoparticles can effectively quench the intrinsic fluorescence of bovine serum albumin through a static quenching mode. The as-synthesized nanoparticles show great potential in biological cell imaging and cancer treatment.

Na3Sc2(PO4)2F3: rational design and synthesis of an alkali rare-earth phosphate fluoride as an ultraviolet nonlinear optical crystal with an enlarged birefringence

An alkali rare-earth phosphate fluoride nonlinear optical crystal, Na3Sc2(PO4)2F3, was synthesized, showing an enlarged birefringence and a short phase matching wavelength.