ISSN 1070-4272, Russian Journal of Applied Chemistry, 2014, Vol. 87, No. 9, pp. 1355−1358. © Pleiades Publishing, Ltd., 2014.
Original Russian Text © A.G. Morachevskii, 2014, published in Zhurnal Prikladnoi Khimii, 2014, Vol. 87, No. 9, pp. 1368−1371.
Thermal Decomposition of Products of Desulfation
of Active Mass of Lead-Acid Batteries
A. G. Morachevskii
St. Petersburg State Polytechnic University, Politekhnicheskaya ul. 29, St. Petersburg, 195251 Russia
Received September 8, 2014
Abstract—The process of thermal decomposition of the active mass of lead-acid batteries after desulfation
(desulfurization) of aqueous solution of sodium carbonate, potassium or ammonia was experimentally studied.
To date, the world production of lead exceeded
10 million tons per year (10615 thousand tons in 2012)
and continues to grow, therewith over 55% of the lead
is melted from recycled materials . Of-life lead-acid
batteries, the world manufacture of which requires on
average at least 75% of the lead produced, are the main
source of recycled raw materials.
Separation of lead-acid batteries (after draining the
electrolyte) into separate factions: metallic (mainly lead-
antimony alloy with alloying components), oxide-sulfate
(active mass of the positive and negative plates), and
ganic (material of body, separators) lies at the heart of
the most environmentally safe technology of disposal of
them. In dry form the oxide-sulfate fraction is 45–50%
by weight of the battery scrap, Lead(IV) oxide PbO
plattnerite, tetragonal modiﬁ cation, and lead sulfate(II),
anglesite are its main components according to the XRD
analysis. There may be small amounts of lead(II) oxide,
tetragonal modiﬁ cation, and metallic lead [1–3].
According to the chemical and electron microscopic
analysis of samples of oxide-sulphate fraction amounts
are comparable and in sum equal to
at least 98% by weight of dry matter. Chemical analysis
performed by various methods in several samples of
oxide–sulphate fraction showed that content of PbSO
is within 44–47% by weight. By data of the electron
microscopy analysis total content of lead was 73.7%,
which is well reproduced by volume of the sample .
Any kind of pyrometallurgical processing of oxide-
sulfate fraction without preliminary removing sulphate
sulfur therefrom is associated with a signiﬁ cant
in temperature of reducing process to form hardly
processed matte and a necessarily capture of sulfur
compounds from the gas phase.
For recycling oxide-sulfate fraction a technology
providing hydrometallurgical operation, desulfation
(desulfurization), which consists in transforming
lead(II) sulfate in its carbonate, is the most favorable.
Grinded initial oxide-sulfate fraction is treated with
aqueous sodium, potassium or ammonium carbonate.
Therewith sulfate ions go into the solution and may
be applied as corresponding commercial products.
Theory and technology of desulfation was studied in
detail [1–8]. PbO
are main components of the
resulting oxide-carbonate cake, moreover the formation
of hydroxycarbonate Pb(CO
Diffraction patterns of the original oxide-sulfate
fraction as well as of oxide-carbonate cake obtained
by desulfation using various reagents are summarized
in [2, 9]. By recording the diffraction patterns it was
shown that by heating to 400°C the oxide-carbonate
cake regardless of the reagent used in desulfation Pb
tetragonal lattice, and phase PbO
, F-cubic lattice,
become the main components of the cake in comparable
amounts (a phase identiﬁ cation was carried out using the
data base JCPDS, 2001). Lead(II) oxide, the tetragonal
modification, is present in very small amounts.