Rate of Rare Earths Leaching in HCl, H2SO4 and HNO3

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.795.1 ◽

2013 ◽

Vol 795 ◽

pp. 1-4 ◽

Cited By ~ 2

Author(s):

Yusoff M.S. Meor

Keyword(s):

Rare Earth ◽

Rare Earth Elements ◽

Rare Earths ◽

Acid Leaching ◽

Leaching Rate ◽

Light Group ◽

Heavy Group ◽

Comparative Rate

Leaching plays an important role in the recovery of rare earth elements. A study on optimizing the relevant parameters such agitation, leaching time and temperature in the dissolution of these elements in HCl, H2SO4 and HNO3 acids were carried out. The recovery of the rare earths is much depended upon the type of acid used in the leaching system. The H2SO4 system shows the highest leached with a rate of 82% while the leaching rate recorded for HCl and HNO3 system were lower at 67% and 59% respectively. Comparative rate of leaching study was also done on the light and heavy rare earths for the three different acid leaching systems and the result shows that the light group has a better rate of leaching than the heavy group.

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The isotopic constitution and atomic weights of hafnium, thorium, rhodium, titanium, zirconium, calcium, gallium, silver, carbon, nickel, cadmium, iron and indium

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1935.0070 ◽

1935 ◽

Vol 149 (867) ◽

pp. 396-405 ◽

Cited By ~ 47

Keyword(s):

Rare Earth ◽

Rare Earth Elements ◽

Rare Earths ◽

Mass Spectra ◽

Mass Number ◽

Atomic Weight ◽

Complete Data ◽

Pure Sample ◽

Titanium Zirconium ◽

Similar Element

An account of experiments has already been given by which the analyses of the rare earth elements were completed with the aid of a particularly favourable arrangement of the anode ray apparatus. This paper contains a description of analyses of other elements made with the same setting and also of some others subsequently made to obtain more accurate and complete data on elements whose constitution had already been provisionally settled. Results (72) Hafnium —Many previous attempts to obtain the mass spectra of this element had failed. For the most similar element, zirconium, the only successful results had been obtained from the fluoride. A pure sample of hafnium fluoride had been kindly provided by Professor G. v. Hevesy, one of the discoverers of the element, and this was incorporated into the anode mixture. The first trial was a failure; but after the work on zirconium described below a second attempt was made, this time with resolved, so that only rough estimates of abundance could be obtained. These were as follows:— Mass numbers . . . . . 176 177 178 179 180 % abundance . . . . . . 5 19 28 18 30 These given a mean mass number 178·5. Applying the same correction as with the rare earths we get atomic weight of hafnium = 178·4 ± 0·2 in fair agreement with the International value 178·6.

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Hydrothermal Synthesis of Rare-Earth Modified Titania: Influence on Phase Composition, Optical Properties, and Photocatalytic Activity

Materials ◽

10.3390/ma12050713 ◽

2019 ◽

Vol 12 (5) ◽

pp. 713 ◽

Cited By ~ 10

Author(s):

Nejc Rozman ◽

David Tobaldi ◽

Uroš Cvelbar ◽

Harinarayanan Puliyalil ◽

João Labrincha ◽

...

Keyword(s):

Optical Properties ◽

Photocatalytic Activity ◽

Rare Earth ◽

Hydrothermal Synthesis ◽

Rare Earth Elements ◽

Rare Earths ◽

Light Absorption ◽

Pure Tio2 ◽

X Ray ◽

Hydroxyl Oxygen

In order to expand the use of titania indoor as well as to increase its overall performance, narrowing the band gap is one of the possibilities to achieve this. Modifying with rare earths (REs) has been relatively unexplored, especially the modification of rutile with rare earth cations. The aim of this study was to find the influence of the modification of TiO2 with rare earths on its structural, optical, morphological, and photocatalytic properties. Titania was synthesized using TiOSO4 as the source of titanium via hydrothermal synthesis procedure at low temperature (200 °C) and modified with selected rare earth elements, namely, Ce, La, and Gd. Structural properties of samples were determined by X-ray powder diffraction (XRD), and the phase ratio was calculated using the Rietveld method. Optical properties were analyzed by ultraviolet and visible light (UV-Vis) spectroscopy. Field emission scanning electron microscope (FE-SEM) was used to determine the morphological properties of samples and to estimate the size of primary crystals. X-ray photoelectron spectroscopy (XPS) was used to determine the chemical bonding properties of samples. Photocatalytic activity of the prepared photocatalysts as well as the titania available on the market (P25) was measured in three different setups, assessing volatile organic compound (VOC) degradation, NOx abatement, and water purification. It was found out that modification with rare earth elements slows down the transformation of anatase and brookite to rutile. Whereas the unmodified sample was composed of only rutile, La- and Gd-modified samples contained anatase and rutile, and Ce-modified samples consisted of anatase, brookite, and rutile. Modification with rare earth metals has turned out to be detrimental to photocatalytic activity. In all cases, pure TiO2 outperformed the modified samples. Cerium-modified TiO2 was the least active sample, despite having a light absorption tail up to 585 nm wavelength. La- and Gd-modified samples did not show a significant shift in light absorption when compared to the pure TiO2 sample. The reason for the lower activity of modified samples was attributed to a greater Ti3+/Ti4+ ratio and a large amount of hydroxyl oxygen found in pure TiO2. All the modified samples had a smaller Ti3+/Ti4+ ratio and less hydroxyl oxygen.

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Process investigation of the acid leaching of rare earth elements from phosphogypsum using HCl, HNO3, and H2SO4

Hydrometallurgy ◽

10.1016/j.hydromet.2016.06.008 ◽

2016 ◽

Vol 166 ◽

pp. 195-204 ◽

Cited By ~ 50

Author(s):

Mugdha Walawalkar ◽

Connie K. Nichol ◽

Gisele Azimi

Keyword(s):

Rare Earth ◽

Rare Earth Elements ◽

Acid Leaching

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Cretaceous-Paleogene boundary Fish Clay at Højerup (Stevns Klint, Denmark): Zn, Pb and REE in kerogen

Journal of the Serbian Chemical Society ◽

10.2298/jsc0804453p ◽

2008 ◽

Vol 73 (4) ◽

pp. 453-461

Author(s):

Pavle Premovic ◽

Maja Stankovic ◽

Mirjana Pavlovic ◽

Milos Djordjevic

Keyword(s):

Rare Earth ◽

Rare Earth Elements ◽

Humic Substances ◽

Rare Earths ◽

Land Surface ◽

Coastal Areas ◽

Previous Hypothesis ◽

Geochemical Analyses ◽

The Impact ◽

Fish Clay

Geochemical analyses of Zn, Pb and rare earth elements (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu) in the kerogen of the black marl at the Cretaceous - Paleogene boundary Fish Clay at H?jerup were performed. Substantial proportions of the Zn, Pb and rare earths were probably contained in terrestrial humic substances (the kerogen precursor) arriving at the marine sedimentary site. This is in accord with a previous hypothesis that kerogen is mainly derived from humic acids of an oxic soil in of the adjacent coastal areas of eastern Denmark. It is also suggested that humics enriched in Zn, Pb and rare earth elements were transported mainly through fluvial transport into the deposition site of the Fish Clay. Local weathering/leaching of the impact-eject fallout on the land surface and local terrestrial rocks by impact-induced? acid surface waters perhaps played an important role in providing Zn, Pb and rare earths to these humic substances. Apparently, chondritic and non-chondritic Zn originated from the impact fallout; Pb and rare earth elements were most likely sourced by exposed rocks in the coastal areas of eastern Denmark.

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