1070-4272/05/7811-1753+2005 Pleiades Publishing, Inc.
Russian Journal of Applied Chemistry, Vol. 78, No. 11, 2005, pp. 1753!1756. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 11,
2005, pp. 1788!1791.
Original Russian Text Copyright + 2005 by Kolyshkin, Poilov.
AND INDUSTRIAL INORGANIC CHEMISTRY
Production of Complex Nitrogen!Potassium
and Nitrogen!Magnesium Fertilizers
from Substandard Urea Fractions
A. S. Kolyshkin and V. Z. Poilov
Perm State Technical University, Perm, Russia
Received May 4, 2005
Abstract-The production of NK and NMg fertilizers of various compositions from urea and finely crystalline
potassium sulfate or urea and caustic magnesite powder was optimized. The commercial characteristics
(qualitative composition, hygroscopicity, and strength) of the granulated NK and NMg fertilizers obtained
were studied. The possibility of undesirable chemical reactions occurring on fusing potassium sulfate or
magnesium oxide with urea in the fertilizer mixture was studied by X-ray phase analysis and IR spectroscopy.
Presently granulated urea produced at the nitrogen
industry plants by the method of prilling (spraying
the melt in a granulation tower) has insufficient mech-
anical strength of the granules, which results in the
formation of a significant part (235 wt %) of substan-
dard product, which is returned to the starting point of
the process (into a urea melt). As a result, the net cost
of commercial urea increases. Moreover, on storage,
transportation, and reloading of urea, its consumer
quality decreases owing to mechanical crushing of
urea granules. The problem is aggravated also by
the fact that the market of prilled urea is narrowing
progressively in the last few years .
At the same time, substandard urea fractions with a
high content of nitrogen would be most appropriate
for use as a nitrogen-containing component of com-
plex fertilizers being in the greatest consumer demand.
The second component of fertilizers could be sub-
standard finely crystalline products containing potas-
sium and magnesium components in the form taken
up by plants. These products are not in demand as
individual fertilizers owing to extremely small size of
By their availability, harmlessness, and correspon-
dence to the claimed characteristics of the end prod-
uct, finely crystalline technical-grade K
used as a potassium-containing component of NK fer-
tilizers, and magnesite caustic powder containing
85 wt % MgO, as a magnesium-containing component
of NMg fertilizers. However, a mechanical mixture of
nutritive components will not have the required com-
mercial characteristics. Therefore, we have suggested
a process for fusing powdered K
and MgO with
substandard fractions of urea.
Understanding of physicochemical features of
processes occurring in a urea melt is very important
for successful promotion of this technology. Thus,
when obtaining mixed complex fertilizers, it is neces-
sary to take into account the fact that some starting
salts and end products must not be mixed, since
undesirable chemical reactions can occur upon their
contact. These reactions can result in losses of nutri-
tive materials and in deterioration of the physical
properties of the fertilizers .
Pozin  indicates that the problem of fertilizer
antagonism has not been studied adequately; however,
he points to a possibility of mixing K
According to [4, 5], complex compounds of the
, and MSO
formed in aqueous solutions of alkali (or alkaline-
earth) metal sulfates and urea. Such compounds may
also be formed in the reaction of molten urea with
dissolved in it.
The suspension of MgO in water has a weakly
basic reaction. Hence, urea can be hydrolyzed to give
as the final product the corresponding carbonate and
O 6 MgCO