STOCKAGE A L'AIR LIBRE DE GRANULES DE SOUFRE

METHOD OF PRILLED SULPHUR STORAGE IN THE OPEN AREA

Abrégé anglais

Abstract
A method for storing prilled sulphur in an open area, employing
the formation of a solidified sulphur plate on the sulphur dump. A layer of
crushed sulphur, or a water spray at a temperature of less than or equal to
the ambient temperature is placed over the surface of the dump. A solidified
layer is then formed by spraying with liquid sulphur. This temperature
permits the formation of a solid crest of sulphur on the dump surface, thus
protecting the interior of the dump, without liquid sulphur penetration into
the body of the dump.

Revendications

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for storing prilled sulphur in the open which
comprises:
(a) forming a prilled sulphur dump;
(b) treating the surface of the dump to preclude liquid
sulphur penetration into the interior of the dump by either apply-
ing a layer of crushed sulphur to the surface of the dump or by
spraying the surface of the dump with water at a temperature equal
to or lower than the ambient temperature; and
(c) spraying the surface of the dump with liquid sulphur
to form a protective layer of solidified sulphur thereon.
2. A method for storing prilled sulphur in the open which
comprises:
(a) forming a prilled sulphur dump;
(b) treating the surface of the dump to preclude liquid
sulphur penetration into the interior of the dump by applying a
layer of crushed sulphur to the surface of the dump;
(c) spraying the surface of the dump with liquid sul-
phur to form a protective layer of solidified sulphur thereon.
3. A method for storing prilled sulphur in the open which
comprises:
(a) forming a prilled sulphur dump;
(b) treating the surface of the dump to preclude liquid
sulphur penetration into the dump by spraying the surface of the
dump with water at a temperature equal to or lower than the ambient
temperature.

4. The method of claim 1, 2 or 3 wherein the dump is con-
tained within a containing wall.
5. The method of claim 1, 2 or 3 wherein the dump is con-
tained within a sectional containing wall, whereby access to the
dump for removing sulphur is obtained by the removal of at least
one wall section.
6. The method of claim 1 or 3 wherein the dump is sprayed
with liquid sulphur immediately after it is sprayed with water.

Description

1~3Z~75
Method of Prilled Sulphur Storage in the Open Area
Background
It has been the practice in most sulphur produc;ng countries to
store sulphur outdoors in large quantities, by piling blocks casted of
liquid sulphur. These blocks may have measurements over 10 meters in height,
and even larger dimensions for length and width. These storage piles may be
anywhere from one hundred thousand to one million tons.
Currently, United States, Mexico, Poland, Iraq and Canada and other
sulphur producers use this method of storage.
The difficulty with this method of storage is the necessity of
crushing the blocks usually prior to transport. The crushing process is
an expensive time consuming one involving large and expensive equipment such
ad diggers, strippers, crushers, antiexplosive and antifire safety devices.
During the removal and preparation for transport of the sulphur,
a great deal of dust pollution occurs, causing noxious work conditions and
environmental pollution. The sulphur itself also becomes contaminated with
moisture.
Apart from the block method of open storage, sulphur has been stored
in loose piles in covered stores, silos, or open stores when contamination
was not important. Due to the fact that it is a loose fine grained material
(angle of repose 28-32), only small amounts could be stored because of the
problem of dust pollution and loss.
Long term storage of prilled sulphur in open areas, without the
dangers of loss or pollution has not hitherto been possible.
.~; -1~ ~
.. ~ . .
. . , ~
- . .
- .
-
.

~l3 Z ~7 5
Prilled sulphur is known to be the best form of sulphur fortransport, handling, dosing and use. It is the function of this invention to
solv~ the problem of its long-term storage. It is especially important when
climate conditions limit the transport period. Also, fluctuating sulphur marketconditions often require storing prill for a few years.
Therefore this invention provides for a method for storing prilled
sulphur in the open, which comprises forming a prilled sulphur dump
advantageously limited by side movable or immovable walls, and treating the
surface of the dump to preclude liquid sulphur penetration into the interior
of the dump. This can be accomplished by either applying a layer of crushed
sulphur to the surface of the dump, or by spraying the surface of the dump
with water at a temperature equal to or lower than the ambient temperature.
Thereafter the surface of the dump is sprayed with liquid sulphur to form a
protective leakproof layer of solidified sulphur thereon.
It is important the solidification takes place immediately after
liquid sulphur touches the surface of the prilled sulphur, without liquid
sulphur penetration inside the body of the dump.
Spraying rate, quantity and temperature of the liquid sulphur are
variable depending upon the store location and climate conditions.
In some cases, it is useful to spray prilled sulphur with water or
cover it with a thin layer of crushed sulphur grains of less than 2mm. before
spraying with liquid sulphur.
The prilled sulphur storage dump protected in this way allows
storage for unlimited time without prill quality changes and losses.
It also facilitates unloading by eliminating handling and crushing large
blocks.
- 2 -
. ~

3L~l3'~7~7
Example I
Prilled sulphur is poured in the open to form a dump. The pouring
system is located in the centre of this area, with the pouring point at a
height of 28m. The sulphur is spread to the circumFerence. The pouring
system is isolated with a concrete wall 28m. high around the circumference
of the 90m. diameter circle. A movable wall of steel 2m. high is constructed.
Sulphur is batched into the space between the pouring system in the centre
and the closed circumference of the circle until it is completely filled,
creating a natural angle of repose of 29.
Next, the surface of prilled sulphur is sprayed with liquid sulphur
from a movable outrigger moving on the circumference of the circle. Spraying
takes place simultaneously along the radius of the circle. The angular
velocity of the sprayer hand shift is 0.06 rad-, with liquid sulphur outlfow
rate 80 litres/sec. The temperature of the liquid sulphur is 145C.
The store is unloaded by opening the movable wall on the circumfer-
ence of the store and employing self-loading devices and belt conveyors.
Example II
Prilled sulphur is poured on an open area having a hardened surface,
limited on two sides with parallel concrete walls located lOm. from each
other and 80m. long. After forming a dump to the height of 8m. on the length
of a part filled with prilled sulphur~ the surface is levelled up and covered
with a layer of crushed sulphur of particles not larger than 2mm. to a
thickness of 3cm. Next, the surface is sprayed with liquid sulphur with a
temperature of 120C. at the rate of 500 litres/min. to create a plate of
solidified sulphur 6cm. thick. After complete solidification, the plate
thickness is increased to 12cm. by gradual solidification of liquid sulphur.
~ .
- . - ~ , :: : - . :
.- . . . .
, ' : . .' - " ': ': ~ . '
, ~

~l~L~3Z~7~ 5
The store is built successively along the walls unti1 it is filled.
Unloading of the store is performed by pneumatic self-load;ng devices.
Example III
Prilled sulphur is poured on an open area of a hardened sulphur
pavement by casting a sulphur plate 30cm. thick, limited on two sides by
parallel walls of movable metal construction, located 30m. from each other
and 160m. long. After forming a dump lOm. high and 5m. long the surface is
levelled up. Water is sprayed on the whole width of the dump from one end
to the other with an outflow rate of 4 litres/min. liquid sulphur sprayers~
move directly and parallel in the same direction as the water sprayers, with
an outflow rate of 200 litres/min. and a liquid sulphur temperature of 123G.
In th;s way a solidified sulphur plate 2cm. thick is formed. It is
successively covered with further charges of liquid sulphur to a flnal
thickness of lOcm. The time of covering (with an ambient temperature of
10C.) is 24 hours.
Building of the dump is carried on successively as the quantity of
produced sulphur grows.
~ 4