Improvements in the Manufacture or Production of Salt from Brine.
Year: 1891

page_text: te of Application, 27th Jan., 1891-Accepted, 23rd Jan., 1892
COMPLETE SPECIFICATION.
Improvements in the Manufacture or Production of Salt from Brine.
Communicated from abroad by Dr. Sigismund Pick, of Szczakowa, in Galicia.
I, ERNEST ORGER LAMBERT, of 39 Lombard Street, in the City of London,
Gentleman, do hereby declare the nature of this invention and in what manner
the same is to be performed to be particularly described and ascertained in and
by the following statement :-
This invention has reference to the manufacture or production in the manner
and by the means hereinafter described of salt from natural or artificial brine by
the treatment of the brine with a chemical solution having a strong affinity for
water, in such a manner as to cause the salt to be precipitated.
In carrying out this invention to produce salt from brine, the process adopted
will depend upon the kind of salt required. Three kinds or grades of common
salt (chloride of sodium) can be produced riz. (1) Flour like salt (2) ordinary
fine salt suitable for table use; and (3) coarse salt. And in order that the modes
of producing the different grades of salt may be readily understood I will, in the
first place, describe by reference to the annexed drawings, the apparatus to be
employed for the purpose.
Fig. 1 is a side elevation of the complete apparatus when constructed with one
evaporator, but as hereinafter stated, more than one evaporator can be employed; .
Fig. 2 is an end elevation; and
Fig. 3 is a plan.
:.
1 and 1ª are tanks to contain brine; 2 and 2ª are tanks to contain the precipi-
tating solution employed which may be chloride of calcium or chloride of
magnesium. In the following description it is assumed that chloride of calcium is
used. The method and apparatus will be. the same if chloride of magnesium be
used. 3 is a mixing tank arranged at a lower level than tanks 1 and 2 and provided
with a discharge pipe 3*; 4 is a pipe with branch connections to each of the five
tanks above mentioned. Each branch is provided with a valve. 1* and 2* are
pipes for supplying brine and water to the tanks 1 and 2 respectively. 5 is a
vacuum filter arranged below the outlet ends of the pipes 1" and 3" connected to
tanks 1 and 3 respectively; this vacuum filter has a branch 6 with valve for
connection with a vacuum pump (not shown) and is used for separating precipitated
salt from the mixture of brine and chloride of calcium. Any other suitable
means may be used for this purpose such as hydro-extractors, or common filters.
7 is a tank to receive chloride of calcium; 8 is a tank to receive brine; and 9 is
a tank to receive mother liquors. These tanks 7, 8 and 9 are, as shown, at a
lower level than the vacuum filter. 10 is a pipe that can be placed in communi-
cation with the under-side of the vacuum filter and with the tanks 7, 8 and 9 by
pipe connections 6*, 7*, 8* and 9* respectively each having a valve. 11, 12
and 13 are three vertical pipes the lower ends of which dip into the tanks 7, 8
and 9 respectively the upper ends of the three pipes being all connected to one
pipe 14. This pipe 14 is connected by a pipe 15 to the upper part of an evapo
rating apparatus A of any suitable construction but preferably of the kind described
in the Specifications of Letters Patent No. 5124 dated 6th April 1887 granted to
George Isaac James Wells, and in the applications for Letters Patent by Edward
George Lawrance respectively No. 3087 dated 26th February 1890 and No. 4532
dated 22nd March 1890 the apparatus described in the last mentioned Specification
being that preferred. Usually it will be advantageous to employ three of these
evaporators, connected up for triple effect working in a manner well understood.
When three evaporators are used, it is preferred to supply the brine or other
liquor to be evaporated, to each one separately.

page_text: 16 is a bent pipe the two legs of which, provided with valves, extend to near the
bottoms of the tanks 8 and 9 respectively. This pipe 16 is connected to the
suction pipe 17 of a pump 18 the delivery pipe 19 of which extends upward and
is connected to a distributing pipe 20 that is provided with outlet branches 20",
20" and 20 terminating above the tanks 1, 2 and 2ª respectively; each of the
branches is provided with a valve as shown. 21 is an outlet pipe with valve for
conducting liquor from the evaporator to the tank 9. 22 is another outlet pipe,
the outer end of which is provided with a flexible pipe 23 by which liquor from
the evaporator can be conducted to one or more of a series of settling or
crystallizing tanks 24. 25, 25 are gutters into. which mother liquors can be
syphoned from the tanks 24 whence it flows to tank 9. The tanks 1, 1, 2, 2ª
and 3 and evaporator A are supported by suitable framework 26 that may be of
wood as shown, or of metal.
With the above described apparatus, salt is produced from brine as follows:-
Brine is introduced into tank 1; solution of chloride of calcium is introduced
into tank 2.
The quantity of salt precipitated will depend upon the strength of the solution
of chloride of calcium employed, the stronger the solution and the greater the
proportion it bears to the quantity of brine to which it is added, the more salt will
be precipitated.
The strength of the solution of chloride of calcium usually employed is 80°
Twaddle at ordinary temperature. The proportions of these two liquors that are
mixed in tank 3 vary according to the percentage of salt it is desired to remove
from the brine in the form of flour salt, in which state it is precipitated by the
chloride of calcium. If it be desired to obtain as nearly as possible the whole
of the salt in the brine in the form of flour salt, about two volumes of the solution
of chloride of calcium of the above mentioned strength is mixed with one volume of
saturated brine. About 98% of the salt will be separated from the brine
with these proportions. If it be desired to obtain say only 25% of the salt- in
the state of flour salt, then about one volume of solution of chloride of calcium
is mixed with two volumes of the brine. Let it be assumed for example that it
is desired to separate as much of the salt as possible in the flour like state.
For this purpose the required quantity of chloride of calcium is first run from
tank 2 through pipe 4 into the tank 3. Then an agitator not shown, but with
which that tank is fitted, is set in motion. The required quantity of brine is then
added from tank 1 through pipe 4. As soon as the whole quantity of brine has
been introduced, the precipitation of the salt and sulphate of lime contained in the
brine is complete, and then the contents of the tank 3 are discharged through
pipe 3 into the vacuum filter 5, or into some other suitable separating apparatus,
as for example a hydro-extractor, by which the salt is separated from the liquor.
Whilst the tank 3 is being emptied, the agitator therein is kept working in order
to prevent settling of the precipitated salt. The solution of chloride of calcium,
containing a small percentage of salt, separated from the salt in the vacuum
filter, is discharged through pipe 10 into tank 7. The salt remaining in the
filter 5 is then washed with about half its volume of fresh brine supplied through
pipe 1 from the tank 1 for the purpose of removing from the salt, all traces of
chloride of calcium. The brine used for the said washing is discharged into tank 8,
and the salt remaining in the filter after the brine is drained off, is then removed
and is ready for drying. The washing and draining operations will occupy about
half an hour. The valve in pipe 11 is then opened, and the solution of chloride
of calcium with a small proportion of salt is forced by atmospheric pressure from
the tank 7 and through the pipe 11 into the upper part of the evaporator A
wherein a partial vacuum is maintained, and the solution is concentrated by the
heat of the steam supplied to the heating chamber of the evaporator as well
understood. If the upper part of the evaporator be too high for the liquor to be
forced therein by atmospheric pressure, due to the vacuum in such upper part, then
the liquor may be forced through the inlet pipe 15 by a pump. When the liquor

page_text: has been concentrated to about 80° Twaddle, it is run by pipe 21 into tank 9.
From this tank the liquor is forced by pump 18 into tank 2 to be again used for
precipitating fresh quantities of salt from brine in the manner hereinbefore
described. By this concentration the remainder of the salt can be obtained from
the mixture of brine and chemicals filtered from the precipitated flour like salt,
and owing to the comparatively small proportion of salt remaining in this mixture
and to the removal of sulphate of calcium from the brine by the chloride of
calcium at the same time as the salt, the evaporation can be effected without
the same liability to formation of scale on the evaporating apparatus as obtained
in the ordinary process in which all the salt is precipitated from brine by evapora-
tion only.
Should any foreign matters accumulate in the solution of chloride of calcium
to such an extent as to interfere with the process, the solution can be concentrated
by evaporation to such a degree that after cooling, the chloride of calcium can
be recovered in the form of crystals so that practically no loss of chemicals need
take place.
If it be desired to obtain in the flour like state, say 25% of the salt contained
in the brine, then about one volume of chloride of calcium is added to two volumes,
of brine from which the salt is precipitated by chloride of calcium in the manner
hereinbefore described. The remaining 75% of salt can then be obtained either
as ordinary fine salt, or in the form of coarse crystals, or partly in one of these
forms, and partly in the other. If only ordinary fine salt is to be obtained, the
liquor, separated from the precipitated salt and containing besides the chloride of
calcium about 75% of the salt contained in the original brine, is concentrated in
the evaporating apparatus A. When the liquor is concentrated to about
80° Twaddle, the whole of the salt will be precipitated in the form of ordinary
fine salt which is filtered in and removed from the vacuum filter A' at the bottom
of the evaporator, in the manner explained in the said former Specifications
No. 5124 of 1887 and No. 3087 of 1890. The remaining solution of chloride of
calcium is then run into tank 9 for re-use as before.
If it be desired to obtain in the form of coarse salt, the whole of the salt
remaining in the liquor after separating the 25% of flour-like salt, then the
liquor is concentrated in the evaporator A only up to the point at which salt
begins to precipitate. To enable this point to be determined, samples of the liquor
are withdrawn from the evaporator from time to time and examined to ascertain
if the precipitation of salt has set in. This liquor is then discharged through the
pipes 22 and 23 into the tanks 24, and is here allowed to cool down. By this
cooling down the salt crystallizes out, salt being more soluble in hot solutions of
chloride of calcium than in cold ones.. By varying the size of the pans, and the
rate of cooling, crystals of salt can be obtained of various sizes the larger the
pans and the slower the cooling, the larger will be the crystals. The mother
liquor remaining in the tanks 24 is syphoned into the gutters 25 and flows into the
tank 9 whence it is again returned to the evaporator and again concentrated,
after which it is again discharged into the tanks 24. These operations are
repeated until the mother liquor consists practically of a solution of chloride of
calcium only. This solution is pumped from tank 9 to tank 2ª by pump 18 in
order to be again used for the purpose described. If it be desired to obtain the
three different kinds of salt mentioned (namely flour-like salt, ordinary fine salt,
and coarse salt) from one charge of brine, then the treatment of the brine with
the chloride of calcium for obtaining say 25% of flour like salt, is the same as
before. The liquor containing the remaining 75% of salt besides the chloride
of calcium, after separation from the flour salt is concentrated in the evaporator A
until the desired quantity of ordinary fine salt is separated. When this has been
done the evaporation is stopped and the liquor remaining in the evaporator is
drawn off and is crystallized in the manner hereinbefore described.
The brine used for washing the salt (and also the brine separated by filtering
from salt precipitated in the evaporator if this brine be not directly returned to

page_text: the upper part of the evaporator) is either forced by atmospheric pressure from
the tank 8 into the evaporator, or is pumped into the tank 1 and salt is produced
from it in the same way as from fresh brine.
By connecting the inlet pipe 15 to the upper part of the evaporator wherein a
partial vacuum is maintained, brine, or solution of chloride of calcium, or other
liquor to be treated, can as hereinbefore mentioned, be caused to flow from a lower
tank, as for example tanks 8 and 9, Figs. 1 and 3, by the pressure of the atmo-
sphere, if the top of the evaporator be not too high, as well understood.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
•
1. The manufacture or production of salt from brine in the manner and by the
means hereinabove described and illustrated, the brine being mixed with a
precipitating solution of a substance having a strong affinity for water (for
examples a solution of chloride of calcium, or chloride of magnesium) the precipi-
tated salt then separated and washed with fresh brine, and the precipitating
solution being re-concentrated for re-use as and by the means specified.
2. The herein described process of producing different kinds or grades of common
salt from brine, by mixing the brine with a precipitating solution of a substance
having a strong affinity for water (for examples a solution of chloride of calcium,
or chloride of magnesium) in such proportion as to precipitate in a flour like state
a part only of the salt contained in the brine, then washing this salt with fresh
brine to remove traces of the precipitant used, then re-concentrating the precipi-
tating solution and separating salt therefrom either in the evaporator or in the
crystallizing tanks, or partly in the evaporator and partly in the crystallizing
tanks according as ordinary fine salt, or coarse salt, or both be required.
Dated this 27th day of January 1891.
W. LLOYD WISE,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.