Improved Process for Obtaining Caustic Soda, Hydrogen, and Chlorine by Electrolysis of Sea Water, and in Treating the Bye-products Obtained During such Process.
Year: 1895

page_text: Date of Application, 2nd Oct., 1895-Accepted, 1st Feb., 1856
COMPLETE SPECIFICATION.
Improved Process for Obtaining Caustic Soda, Hydrogen, and
Chlorine by Electrolysis of Sea Water, and in Treating the
Bye-products Obtained During such Process.
I GIOVANNI BATTISTA BALDO Industrial Chemist and Professor of the Real
Superior School in Trieste, Austria residing in Via Stadion No. 16, 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:—
According to this invention I evaporate sea water in very large vessels until
reduced to about one half of its original bulk or a density of about 8° Beaumé equal
to specific weight 1.060.
I then electrolyse the resultant product and also treat certain of the bye-products
produced during the process.
In order that the method of carrying out my invention may be clearly understood
reference is made to the accompanying drawing which shows one form of apparatus
which may be employed. In said drawing
a represents an ordinary porous pot.
b an iron or suitable metal surrounding vessel also acting as the negative
electrode.
c varnished or protected part of pot a that prevents the chlorine and hydrogen
given off in a and b respectively from recombining.
d positive electrode of carbon.
e and connections for the positive and negative wires from the dynamo.
g tube for escape of the chlorine gas.
tube for escape of the hydrogen gas.
i glass or other suitable insulator.
1 stopper or tap at bottom of porous pot.
m asbestos or other ring for closing vessel b and at same time insulating it from
the porous pot.
n tube for discharging contents of vessel b.
o tube for discharging contents of the porous pot.
p cover of porous pot.
q inlet tube for charging the porous pot.
inlet tube for charging the vessel b.
s water or cooling jacket.
t, u and v level of liquids in respective vessels.
In carrying out the process with the apparatus as described I first fill the
vessels a bands with the partially evaporated sea water, with pure or potable
water, and with cooling water or other medium respectively. On then passing a
suitable electric current from e to f through the electrolytes the sea water is
decomposed the chlorine gas given off in pot a escapes by pipe g to any suitable
holder and may be used in the usual way for the production of hypochlorites,
chlorates or for other purposes. The sodium which will of course tend to form
near the negative electrode combines with the water in vessel b and forms pure
caustic soda while the hydrogen also given of in said vessel escapes by pipe / and
may be collected and utilized as desired. The partially evaporated sea water is

page_text: replenished in pot a from time to time and when the caustic in vessel b has reached
the desired degree of concentration it may be drawn off through pipe n.
The residue in the porous pot contains chloride of sodium which has not been
decomposed and free sulphuric acid.
These
This residue I distill, rejecting about the first three quarters (4) that pass over.
The last quarter distilled contains dilute hydrochloric acid produced by the action
of the sulphuric acid on the chloride of sodium. The dry residue remaining after
distillation is formed of sulphate of magnesium, chloride of sodium etc.
substances are collected and heated to redness in iron or other vessels and the acid
vapours driven off therefrom are passed through a saturated solution of chloride of
barium to deprive them of any traces of sulphuric acid, and the resultant vapours
of pure hydrochloric acid I pass through the weak hydrochloric acid collected from
the first distillation and thus obtain a pure hydrochloric acid of any strength
.desired.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The improved process for producing chlorine, hydrogen and pure caustic soda
from sea water substantially as set forth.
2. The improved process for producing chlorine hydrogen and caustic soda from
sea water and hydrochloric acid from the bye-products obtained in such process
substantially as set forth.
Dated 25th day of September 1895.
Prof. GIOVANNI B. BALDO.