PROCESS FOR THE PREPARATION OF ANHYDROUS SODIUM SULFATE FROM A BRINE

PROCEDE POUR LA PREPARATION DE SULFATE DE SODIUM A PARTIR D'UN RESERVOIR DE SAUMURE

English Abstract

PROCESS FOR THE PREPARATION OF
ANHYDROUS SODIUM SULFATE FROM A BRINE

ABSTRACT


Process for the preparation of anhydrous sodium sulfate
from a brine containing sodium sulfate, comprising: mining
the brine from the underground; crystallizing the brine by
cooling it to crystallize a fine dust of sodium sulfate
hydrated with ten molecules of water known as Glauber salt;
separating the Glauber salt from the exhausted solution;
melting the Glauber salt to dissolve the crystals of sodium
sulfate in its own crystallization water to obtain a sodium
sulfate saturated solution with 17% of solids of anhydrous
sodium sulfate; separating the crystals of anhydrous sodium
sulfate from the saturated solution; recycling the remaining
saturated solution to the crystallization step; and drying the
anhydrous sodium sulfate crystals.

Claims

WHAT IS CLAIMED IS:
1. Process for the preparation of anhydrous sodium
sulfate from a brine containing sodium sulfate, comprising:
mining the brine from the underground; crystallizing the brine
by means of cooling to obtain a fine dust of sodium sulfate
hydrated with ten molecules of water known as Glauber salt;
separating the Glauber salt from the exhausted solution;
melting the Glauber salt to dissolve the sodium sulfate
crystals in its own crystallization water to obtain a
saturated solution with approximately 17% by weight of solids
of anhydrous sodium sulfate; separating the anhydrous sodium
sulfate crystals from the saturated solution; recycling the
remaining saturated solution to the crystallization step; and
drying the anhydrous sodium sulfate crystals.
2. The process according to claim 1, wherein separation
of the Glauber salt from the exhausted solution is carried by



settling and filtering, refusing the exhausted solution.
3. The process according to claim 1, wherein separation
of the solids of anhydrous sodium sulfate after the melting of
the Glauber salt is carried out by settling and centrifuging,
recycling the remaining saturated solution to the
crystallization step.
4. The process according to claim 1, wherein the solids
of anhydrous sodium sulfate are dried in a heart furnace with
air at a temperature of about 100°C and then cooled to be
packaged, separating the residual water.

Description

BACKGROUND OF THE INVENTION
This invention relates to a process for the preparation
of anhydrous sodium sulfate from a brine and, more
specifically, it relates to a process to produce anhydrous
sodium sulfate from a brine which has sodium sulfate in
solution.
The known conventional process to produce sodium sulfate,
starts from a brine which is extracted from the underground
and stored in a reservoir and therefrom it is conducted to a
crystallizer wherein, by cooling, crystals are produced in the
form of a fine powder of sodium sulfate hydrated with ten
molecules of water, known a~ Glauber salt (Na2S04-10H20), which
is settled, then filtered and conducted to a reservoir wherein
it is melted to dissolve the crystals of sodium sulfate in its
own hydrating water, to produce a saturated solution of sodium
sulfate with 17% of solids, which is then partially evaporated
to obtain a suspension of anhydrous sodium sulfate with 20% of
solids in a saturated ~olution, said suspension is then
settled and centrifuged to concentrate the solids of anhydrous
sodium sulfate which are separated and dried recycling the
remaining saturated solution back to the evaporation step.
In said conventional process the crystallization of the
Glauber salt is carried out by cooling it at about 30C to
about 20~C in a special crystallizer.
The evaporation step has been considered as strictly
necessary to concentrate the solids of anhydrous sodium
sulfate up to 20%.
With these antecedents the inventor ~ound that if after
the melting of the hydrated ~odium ~ulfate it is obtained a


17~ of solids of anhydrous sodium sulfate, this solids could
be directly separated by settling and centrifugi~g,
conditioned to recycling the saturated solution to the
crystallization step to avoid both, the wasting of the
solution, and the evaporation step and e~uipment with its
associated energy consumption, because only an additional 3%
of the total production is attributable to this evapotation
step in return for a considerable amount of equipment, energy
and maintenance.
O~JECTS OF THE INVENTION
It i8 therefore a main object of the instant invention,
to provide a process for the preparation of anhydrous sodium
sulfate from a brine containing sodium sulfate.
It is an additional object of the instant invention to
provide a process for the preparation of anhydrous sodium
sulfate of the aforesaid nature, by means of which the
anhydrous ~odium sulfate is directly obtained after the
melting of the Glauber ~alt and thereafter the sodium sulfate
saturated solution i8 recycled to the crystallization step,
avoiding in this way the evaporation step of the conventional
process.
It is an additional object of the instant invention, to
provide a process for the preparation of anhydrous sodium
sulfate, of the aforesaid pointed nature, in which the
evaporation step and equipment and their associated energy
consumption are avoided.
These and other objects and advantages of the instant
invention will be readily apparent for those skilled in the
art, from the detailed description of the invention and the


accompanying drawing.
~RIEF DESCRIPTION OF THE DRAWING
Figure 1 is a block diagram of the process for the
production of anhydrous sodium sulfate from a brine containing
sodium sulfate.
DETAILED DESCRI~TION OF THE INVENTION
Referring to Figure 1 it is disclosed a process for the
production of anhydrous sodium sulfate from a brine of sodium
sulfate, which comprises:
a) mining the brine of sodium sulfate from an
underground deposit;
b) storing the brine in a reservoir;
c) crystallizing the Glauber salt in an exhausted
solution which comprises a little quantity of
sludges and other impurities by cooling in a special
crystallizer;
d) settling and filtering the Glauber salt separating
the exhausted solution with sludges and impurities;
e) melting the Glauber salt at a temperature of
approximately 60C to dissolve the Na,SO4-10H2O in
its own crystallization water to obtain a suspension
which comprises a sodium sulfate saturated solution
and 17% by weight of anhydrous ~odium sulfate
crystals of the total weight of the Glauber salt
from which lt was originated:
f) settling and centrifuging the resulting suspension
to separate the anhydrous sodium sulfate crystals;
g) recycling the saturated solution remaining from the
settling and centrifuging, to the crystallization



step and;
h) drying the anhydrous sodium sulfate SFA in a heart
furnace through which air indirectly heated in a
boiler to about 100C is blown to separate the
remaining water AR.
It should be understood that the scope of the instant
invention is not limited to the specific examples of process
and equipment above described and that those skilled in the
art will be enabled to make multiple variations in the process
steps and operation conditions of the instant invention and
that this changes will fall within the spirit and scope of the
invention as claimed hereafter.