recovery of the REE concentrate
According to M.N. Nabiev, with the nitric acid decomposition of phosphorites, regardless of acid concentration,
the extraction of rare earths from the solution is about 88-99%). He established the following optimal conditions for the
extraction of rare earth phosphates: a) the concentration of the liquid phase is 35 %, Ca (NO
3
)
2
and 9.5 % Р
2
О
5
,
respectively; b) the temperature of the separation process is 60-80 °C; c) neutralization with ammonia of free nitric acid
and about 50% of the first hydrogen ion of phosphoric acid; d) the isolation of rare earth phosphates from the solution
is expediently carried out by decantation. Under these conditions, the degree of precipitation of rare earths is about 70-
80 % of the total amount in apatite.
NAL
for obtaining environmentally
friendly fertilizers
Nitric acid extract
Decomposition
Na
2
SiF
6
Neutralization with ammonia
Desulfurization
REE concentrate
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