ISSN 1070-4272, Russian Journal of Applied Chemistry, 2015, Vol. 88, No. 10, pp. 1589−1593. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © V.N. Martsul’, I.Yu. Kozlowskaya,
2015, published in Zhurnal Prikladnoi Khimii, 2015, Vol. 88, No. 10, pp. 1404−1408.
AND TECHNOLOGICAL PROCESSES
Recovery of Lanthanum from Acid Leaching Solutions
of Spent Cracking Catalyst
V. N. Martsul’ and I. Yu. Kozlowskaya
Belarussian State Technological University, Minsk, ul. Sverdlova 13A, 220006 Belarus
Received January 19, 2015
Abstract—Results are presented of a study aimed to recover lanthanum in the presence of aluminum from acid
solutions obtained in leaching of a spent cracking catalyst by precipitation with a solution of ammonia and so-
dium hydrocarbonate. The conditions for selective precipitation of lanthanum were examined. The composition
and properties of the resulting lanthanum-containing precipitates were analyzed. Various variants of their use
At present, rare-earth elements (REEs) are widely used
in various industries. According to ,about 20% of their
total consumption is accounted for by the manufacture
of catalysts , including cracking catalysts becoming
wastes on expiration of their service life. The world’s
consumption of cracking catalysts is 600 thousands tons
per year , with the average content of REEs in these
catalysts reaching 2% (mostly lanthanum). This makes
topical a search for ways to use spent cracking catalysts
(SCCs) as raw materials for manufacture of REEs.
Lanthanum compounds are produced from various
raw materials (bastnaesite, monazite, loparite), including
wastes (phosphogypsum, bottom ash, etc.) [3–7].
Irrespective of a raw material used, lanthanum compounds
are obtained in three main stages: extraction into solution
(leaching), isolation from solution (multistage extraction,
precipitation, selective oxidation–reduction, sorption on
an ion-exchange material with subsequent elution, etc.),
and synthesis of high-purity lanthanum compounds.
REEs are predominantly recovered from raw materials by
agitation leaching with acid solutions. The fundamental
aspects of the lanthanum leaching process were considered
for the object of the present study, spent cracking catalyst,
in . A speciﬁ c feature of SCC leaching solutions is that
their main components are lanthanum and aluminum at a
ratio of 3.1–4.5 and an insigniﬁ cant amount of impurities.
This circumstance makes it possible to avoid a multistage
extraction in recovery from SCC leaching solutions. The
properties of insoluble lanthanum compounds, such as
lanthanum hydroxide, carbonate, phosphate, ﬂ uoride,
and oxalate have been sufﬁ ciently well studied. However
compounds with difﬁ cultly prognosticated composition
may be formed in precipitation of lanthanum from an SCC
leaching solution because of the presence of aluminum
and microscopic impurities.
The goal of our study was to recover lanthanum from
nitric and sulfuric acid solutions formed in leaching of a
spent cracking catalyst to obtain usable products.
Comparative analysis of possible ways to precipitate
lanthanum as difﬁ cultly soluble compounds, made with
consideration for the composition of SCC leaching
solutions, shows that the precipitation in the form of
hydroxides and carbonates is the most suitable. Because
the pH ranges in which aluminum and lanthanum
hydroxides are formed are different, it is possible, in
principle, to selectively recover lanthanum compounds
from leaching solutions. If lanthanum is precipitated
from SCC leaching solutions as carbonates, it would be
expected that the concentration of lanthanum in the ﬁ nal
product should be higher because the precipitation of
lanthanum occurs at pH 4.5–4.7 and aluminum will not
fully pass into the precipitate in this pH range.