Note: Descriptions are shown in the official language in which they were submitted.
2043873
The present invention relates generally to a process
for the manufacture of granules of agglomerated sulphur
nutrients comprised of sulphur particles ground to at
least 200 U.S. mesh and bound together by a binder
dispersant. The invention also relates to nutrients
produced by this process, namely granules comprised of
elemental sulphur or elemental sulphur and sulphate
containing particles, wherein the individual particles
are 200 U.S. mesh or finer.
The process used in the manufacture of the
comminuted agglomerated sulphur product includes
comminution of elemental sulphur or sulphate containing
compounds to at least 200 U.S. mesh, mixing the
individual sulphur particles with an organic binder
dispersant, granulating the binder dispersant sulphur
particles, and drying said granules to set the binder
dispersant.
The agglomerated sulphur or sulphate containing
granules manufactured by the process of this invention
are dispersible in water tanks to prepare a sulphur
suspension nutrient or the granules may be used in dry
blends as fertilizer in which event the granules are
broken down by moisture in the soil. Elemental sulphur
is not soluble and must be broken down by interaction
with soil microorganisms into inorganic sulphate, the
plant available form. The conversion of elemental
sulphur to inorganic sulphate is dependent upon the
dispersion rate of the granules, the size and shape of
the elemental sulphur particles in the granules, and the
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availability of microorganisms. The dispersion rate of
granules is dependent upon the characteristics of the
binder dispersant.
Elemental sulphur particles of a particle size
smaller than that passing a 200 U.S. mesh screen responds
quickly to microorganisms. As the particle si~e of the
elemental sulphur increases above a particle size which
will pass through a 200 U.S. mesh screen, the surface
area per unit weight of sulphur decreases and the rate of
conversion to usable sulphates decreases substantially.
Elemental sulphur particles containing 5 to 10%
swelling clay are sold as sulphur bentonites. In sulphur
bentonite fertilizers the sulphur particles normally
range in size from 50 to 75% less than 40 mesh and 15 to
25% smaller than 200 mesh. These bentonite clays with a
majority of elemental sulphur particles in the 40 mesh
size take substantially a year before fifty per cent of
the sulphur is converted to plant available sulphate.
When the elemental sulphur particle size is 200 mesh or
finer, conversion to fifty per cent plant available
sulphate can be achieved in 5 weeks where there is
sufficient moisture and microorganisms.
Another fertilizer incorporating elemental sulphur
is urea sulphur (36-0-0-20S). The urea sulphur is
manufactured by the drum granulated urea-sulphur melt
process using molten sulphur. The urea-elemental sulphur
mix contains both nitrogen and sulphur and provides
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significantly less elemental sulphur per unit of weight
than a comparable elemental sulphur made by the process
of this invention.
Summary of the Invention
The present invention relates to a process for
producing a granulated oxidizable sulphur product for
bulk blending or fluid suspension comprised of elemental
sulphur particles which will pass through a 200 mesh
screen and an organic binder. In the first step of the
process elemental sulphur is comminuted and classified to
remove particles of 200 U.S. mesh or less. The particles
of 200 U.S. mesh or less are then mixed with a binder
dispersant. The binder dispersant must be capa~le of
binding particles together into granules, dried into a
finished product which is dispersible into particles by
water in the field or in a container. One satisfactory
binder dispersing agent is calcium lignosulphonate. The
calcium lignosulphonate is heated to 90 to 100
Fahrenheit in a heater and delivered through a metering
pump to a mixer where it is vigorously mixed with the
comminuted particles of elemental sulphur.
The particles of elemental sulphur containing binder
dispersant proceed to a granulator. In the granulator
the small particles of elemental sulphur and binder
dispersant are rolled relative to one another until
granules of 10-16 U.S. mesh or other desired mesh sizes
are formed for dr~ blend elemental sulphur. The granules
2043873
leaving the granulator are transported to a dryer where
the granules are dried. From the dryer the granules are
transported to a multi-deck screen. In the manufacture
of one product granules comprised of 90-95% elemental
sulphur granules of a granular size of 10-16 U.S. mesh
suitable for dry blending with other blends are removed
on one screen and granules of 16-30 U.S. mesh are
separated on another screen. The granules are
transported either directly to the bagger or to temporary
storage before bagging.
The instant invention provides a process for the
preparation of elemental sulphur granules composed of
particles of elemental sulphur of 200 U.S. mesh or less
bound by an organic binder dispersant and suitable for
dry blending with other fertilizers or independent
application.
The drawing which is shown as Figure 1 is a
schematic drawing of the principal apparatus used in the
process of this invention.
As shown in Figure 1, elemental sulphur is stored in
an elemental sulphur storage tower 9. The elemental
sulphur is preferably in chunks of three quarters of an
inch or less suitable for introduction into a grinder 10.
In the instant process a 200 hundred horse power grinder
is used to comminute the elemental sulphur into particles
of 200 U.S. mesh or less. An air classifier 11 which
forms part of the grinder is used to separate the smaller
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particles of elemental sulphur to storage and the
particles above 200 U.S. mesh are recirculated through
the grinder 10 for further comminution.
The other element used in the agglomeration process
is Marasperse 5558, a calcium lignosulphate used as a
binder dispersant and manufactured by Reed Lignin
Incorporated, of Greenwich, Connecticut, U.S.A. The
binder dispersant is stored in storage tank 13.
Marasperse 5558 is viscous when cold and is heated up to
between 70 and 100C in heater 14 prior to use and held
in a holding tank. The heated Marasperse 5558 is
transmitted from the heated holding tank through a
metering pump to a mixer 15 where the binder dispersant
is mixed with the comminuted elemental sulphur particles.
The elemental sulphur particles and calcium
lignosulphate are mixed thoroughly in mixer 15. A
turbulator is employed for mixing, however other devices
which will vigorously mix the elemental sulphur and the
binder dispersant may be used.
The Marasperse 5558 used is 58% solids and about 4
to 5% by weight of water is added to the Marasperse 5558
as it is introduced into the mixer 15.
From the mixer 15 the elemental sulphur granules and
retained binder dispersant are transported to a pan
granulator 16. Other apparatus for building up granules
may be used. A fine mist of water is applied as required
to the elemental sulphur particles containing binder
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dispersant as required to promote agglomeration to form
granules of six U.S. mesh or less or other desired
granule size at which granules fall off the pan
granulator 16 and are transported to a vibrating fluid
bed dryer 17.
The granules of elemental sulphur leaving the
agglomerator have a moisture content between 10 and 12~.
The granules of elemental sulphur and binder are dried as
they are transported along the fluid bed dryer 17 until
the moisture content of the elemental sulphur granules
leaving the fluid bed dryer 17 have a moisture content
below three-quarters of one percent and preferably below
one-half of one-percent.
From the fluid bed dryer 17 the elemental sulphur
granules are transported to a multi deck screen 18 where
granules of 16 to 30 U.S. mesh suitable for use for lawn
and garden are removed on one screen and granules of 6 to
16 U.S. mesh suitable for dry blending agricultural use
are removed on another screen. Depending on demand
larger granules may be comminuted and returned to the
mixer 15.
The process creates very fine elemental sulphur
particles, particularly during the grinding stage and the
mixing stage. Such fine materials may form a combustible
or explosive mass and the process must be monitored,
recorded and controlled for automatic shut down in the
known manner.
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The process of this invention has been used to
manufacture 0-0-0-(90-95) elemental sulphur granules
comprised of particles of 200 U.S. mesh or less bound by
the dispersible calcium lignosulphate described in this
application. The 0-0-0-(90-95) elemental sulphur when
granulated is dry blendable with other nutrients to
provide a blended fertilizer having the proper amount of
sulphur for the soil being fertilized. The 0-0-0-(90-95
nutrient is 90-95% elemental sulphur by weight and all
the particles forming the granules are two hundred U.S.
mesh or less such that the elemental sulphur particles
are immediately available for conversion by
microbiological activity to the sulphate form in which
the sulphur is available to the plants.
Even finel~ divided elemental sulphur particles
under 200 U.S. mesh requires up to five weeks in the
presence of sufficient moisture and microbiological
activity to be substantially transformed into the plant
available sulphate form. In order to offer a nutrient
for use or blending containing immediately available
sulphate, a mixture of 60% by weight of elemental sulphur
particles of less than 200 U.S. mesh is mixed with 30~ by
weight of crystals of ammonium sulfate ground to 200 U.S.
mesh or less and 10% by weight of Marasperse 5558 in the
mixer. After mixing this mix is treated in the sam~
manner as the previously described 0-0-0-(90-95)S
elemental sulfur product. The product containing
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ammonium sulfate described above results in a nutrient
having the composition 7-0-0-68S.
Both of the granular products referred to above
offer the end user the option of using the products in
dry blends or as a suspension nutrient because of the
dispersion capability of the binder dispersant.
The 0-0-Q-(90-95)S and 7-0-0-68S are composed of
bound particles which are 100% 200 U.S. mesh and 90% 300
mesh. As the particles bound in the granules become
bigger than 200 mesh the particles react more slowly to
transformation to sulphate by microbiological activity.
The above disclosure has been set forth in order to
illustrate the nature of this invention and the manner of
practicing the same and changes can be made in the
process and the product without deviating from the spirit
of the invention.
