Improvements in the Employment of Sulphuretted Hydrogen in the Manufacture of Alkali and Certain Bye-products.
Year: 1890

page_text: Date of Application, 5th Nov., 1890
Complete Specification Left, 5th Aug., 1891-Accepted, 5th Sept., 1891
PROVISIONAL SPECIFICATION.
Improvements in the Employment of Sulphuretted Hydrogen in the
Manufacture of Alkali and Certain Bye-products.
1 JAMES SIMPSON of 84 Rumford Place Liverpool in the County of Lancaster,
Alkali Manufacturer, do hereby declare the nature of this invention to be as
follows:-
This invention refers to a cheap and efficient method of manufacturing alkali
from sulphate of soda and is specially advantageous for the utilization of certain
descriptions of sulphate of soda which are at present either not used at all-or
only to a moderate extent. Among these include the waste liquors from the wet
copper process-cylinder cake-nitre cake-and the natural deposits of sulphate of
soda which are found in Spain, Austria, America and elsewhere.
In carrying my invention into practice I employ a saturated solution of sulphate
of soda which I first purify and neutralize by mixing with it a small percentage
of sulphydrate of calcium or other suitable soluble sulphides such as sulphide of
ammonium for the purpose of neutralizing any acid that may be present and also
for precipitating any iron existing in the solution. The insoluble matter is
allowed to settle out and the clear supernatant liquor is drawn off and employed in
the process as described later on.
I also employ a strong solution of calcium sulphydrate which I manufacture in
the manner hereinafter described and I cause the said calcium sulphydrate solution
to react on the sulphate of soda solution-whereby sulphate of lime is precipitated
while sulphide or sulphydrate of sodium remains in solution. This latter is then
removed to a series of towers or vessels such as the Solvay Carbonating Plant and
is treated with carbonic acid gas-thereby precipitating bi-carbonate of soda and
giving off sulphuretted hydrogen mixed with nitrogen.
The latter is allowed to escape into the atmosphere after passing through a milk
of lime washer and iron oxide bed to eliminate any traces of sulphur.
The lime resulting from the burning of the limestone in the kiln for supplying
the carbonic acid gas-is then agitated in water till it forms milk of lime-and gas
containing sulphuretted hydrogen (resulting from the decomposition of the sulphide
of sodium by means of carbonic acid as aforesaid) is forced through the said milk
of lime in a series of vessels or towers such as the Solvay Carbonating Plant
whereby sulphydrate of calcium is formed in solution and is employed for the
treatment of a further quantity of sulphate of soda-and the operation is repeated.
The series of towers employed for this operation should be sufficient in height and
number to ensure that the milk of lime contained in the tower receiving the fresh
gas shall be converted into sulphydrate of calcium before any sulphuretted
hydrogen shall escape at the final tower. To prevent nuisance it is desirable to
send the gas from the final tower through a bed of oxide of iron to arrest any
trace of sulphur.
The rapidity of the absorption of the sulphuretted hydrogen in the milk of lime
is greatly increased by the pressure at which it comes from the carbonating plant;
and the reaction between the sulphate of soda and sulphydrate of calcium solutions
can be also facilitated by conducting the reaction in a closed vessel under steam
pressure of 60 to 80 lbs. per square inch-sulphate of lime being insoluble at the
In order to prevent any reverse
temperature corresponding to this steam pressure.
action it is advisable to maintain the pressure while the sulphide of sodium is
being drawn off.
As in this process the sulphuretted hydrogen is used repeatedly-it is obvious

page_text: that the expense of making good any loss incurred in the manipulation of this
inexpensive re-agent must be very small.
The bicarbonate of soda produced in the process is converted into any desired
form of alkali by well known methods-while the sulphate of lime can be used in
agriculture or for the manufacture of plaster of paris.
In addition to the lime required for the sulphydrate of calcium--the kiln will
produce a surplus-which can be sold or used for other purposes.
Dated the Fourth day of November 1890.
Per pro J. T. KING,
J. Johnson,
Agent.
COMPLETE SPECIFICATION.
Improvements in the Employment of Sulphuretted Hydrogen in the
Manufacture of Alkali and Certain Bye Products.
I JAMES SIMPSON of 84 Rumford Place Liverpool in the County of Lancaster
Alkali Manufacturer 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 refers to a cheap and efficient method of manufacturing alkali
from sulphate of soda and is specially advantageous for the utilization of certain
descriptions of sulphate of soda which are at present either not used at all-or
only to a moderate extent. Among these I include the waste liquors from the wet
copper process--cylinder cake, nitre cake, and the natural deposits of sulphate of
soda which are found in Spain, Austria, America, and elsewhere.
In carrying my invention into practice, I employ a saturated solution of sulphate
of soda which I first purify and neutralize by mixing with it a small percentage of
sulphydrate of calcium, or other suitable, soluble, sulphides such as sulphide of
ammonium, for the purpose of neutralizing any acid that may be present and also
for precipitating any iron existing in the solution. The insoluble matter is
allowed to settle out and the clear supernatant liquor is drawn off and employed in
the process as described later on.
I also employ a strong solution of calcium sulphydrate which I manufacture in
the manner hereinafter described and I cause the said calcium sulphydrate solution
to react on the sulphate of soda solution, whereby sulphate of lime is precipitated
while sulphide or sulphydrate of sodium remains in solution. This latter is then
removed to a series of towers or vessels such as the Solvay Carbonating Plant and
is treated with carbonic acid gas, thereby precipitating bicarbonate of soda and
giving off sulphuretted hydrogen mixed with nitrogen. The latter is allowed to
escape into the atmosphere after passing through a milk of lime washer and iron
oxide bed to eliminate any traces of sulphur.
The lime resulting from the burning of the limestone in the kiln for supplying
the carbonic acid gas, is then agitated in water till it forms milk of lime, and gas
containing sulphuretted hydrogen (resulting from the decomposition of the sulphide
of sodium by means of carbonic acid as aforesaid) is forced through the said milk
of lime in a series of vessels or towers such as the Solvay Carbonating Plant,
whereby sulphydrate of calcium is formed in solution and is employed for the
treatment of a further quantity of sulphate of soda and the operation is repeated.
The series of towers employed for this operation should be sufficient in height and
number to ensure that the milk of lime contained in the tower receiving the fresh
gas shall be converted into sulphydrate of calcium before any sulphuretted
hydrogen shall escape at the final towers. To prevent nuisance it is desirable to
send the gas from the final tower through a bed of oxide of iron to arrest any trace
of sulphur.
The rapidity of the absorption of the sulphuretted hydrogen in the milk of lime

page_text: is greatly increased by the pressure at which it comes from the carbonating plant :
and the reaction between the sulphate of soda and sulphydrate of calcium solution
can be also facilitated by conducting the reaction in a closed vessel under steam
pressure of 60 to 80 lbs. per square inch, sulphate of lime being insoluble at the
temperature corresponding to this steam pressure. In order to prevent any reverse
action it is advisable to maintain the pressure while the sulphide of sodium is being
drawn off.
As in this process the sulphuretted hydrogen is used repeatedly, it is obvious
that the expense of making good any loss incurred in the manipulation of this
inexpensive reagent must be very small.
The bicarbonate of soda produced in the process is converted into any desired
form of alkali by well known methods, while the sulphate of lime can be used in
agriculture or for the manufacture of plaster of paris or can be made into
sulphydrate of calcium and employed for any desired purpose.
In addition to the lime required for the sulphydrate of calcium, the kiln will
produce a surplus which can be sold or used for other purposes.
The diagram herewith illustrates a combination of apparatus used in carrying
my invention into effect. a, a', represents a lime kiln and scrubber. & blowing
engine. c, d, e, three series of absorbing vessels in which the reactions between
the sulphide of sodium and carbonic acid gas, between lime from the kiln a and
sulphuretted hydrogen, and between the sulphydrate of calcium and sulphate of
soda respectively are carried out. f, g, two sets of filter beds. h, pipe and valve
connections. In the vessels c sulphide of sodium in solution is acted on by carbonic
acid gas from the kiln a and bicarbonate of soda is precipitated whilst sulphuretted
hydrogen is evolved. The bicarbonate is run on the filter, whilst the sulphuretted
hydrogen passes through the series of vessels d containing lime, preferably obtained
from the kiln a, mixed with water so as to form milk of lime. Any nitrogen or
inert gas passes away from the vessel d, whilst the sulphydrate of calcium obtained
is run into the series of vessels e. Salt cake is mixed with the sulphydrate of
calcium in the vessels e, and sulphate of lime and sulphide of sodium are formed
which latter is run into vessels c, whilst the sulphate of lime is separated out on
the filter g.
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
First. In the manufacture of alkali and sulphate of lime by means of the
reaction between sulphate of soda and sulphydrate of calcium, the repeated
employment of sulphuretted hydrogen under pressure for converting the lime into
sulphydrate of calcium in the manner described.
Second. The arrangement and combination of apparatus substantially as above
described for the purpose set forth.
1001
Per pro J. T. KING,
J. Johnson,
Agent.