Affiliation:
1. Faculty of Natural Sciences, Novosibirsk State University, Novosibirsk, Russia
2. Institute of Solid-State Chemistry and
Mechanochemistry SB RAS, Novosibirsk, Russia
3. Institute of Solid-State Chemistry and
Mechanochemistry SB RAS, Novosibirsk, Russiaon
Abstract
Background:
Brown coals are recognized as promising sources of rare earth elements
(REEs). Rare earths are present in both the mineral and organic parts of brown coal.
Objectives:
This study was conducted to investigate the influence of preliminary mechanical activation
in the process of sample preparation prior to analyzing the concentrations of rare earth elements
in brown coal samples of various origins and compositions
Methods:
Four coal samples from different deposits in Russia were selected for the study. Samples
were treated with mechanical activation, without reagents, or mechanochemical activation, with humic
acids added externally as reagents. X-ray phase analysis was carried out with the selected samples.
The quantities of rare-earth elements present in the samples were studied by the method of
high-sensitivity inductively coupled plasma mass spectrometry (ICP-MS).
Results:
It was found that the mechanical activation of coal before dissolution in a mixture of nitric
and hydrofluoric acids leads to an increase in the determined concentration of rare earth elements.
For this study, the expediency of using only nitric acid as an optimal solvent for the elemental analysis
of coal samples was shown. The total concentration of all REE after dissolution of nitric acid and
mechanochemical activation with humic acid reached 2456 g/t in Vanchin coal, 968 g/t in Azeysky
coal, and 24 g/t and 150 g/t in Itatsky and Spetsugli coals, respectively.
Conclusion:
Mechanical activation and mechanochemical treatment can greatly help to facilitate
sample preparation of natural objects, such as coals for elemental analysis, but in some cases, only a
change of solvent is sufficient. When developing technology for concentrating rare earth elements
from coal involving grinding, it is necessary to take into account the fact that mechanical activation
of coal changes its tendency to dissolve, which may affect the results of the analysis and should be
taken into account during experiments.
Publisher
Bentham Science Publishers Ltd.