IMPROVEMENTS IN AND IN
Year: 1882

page_text: LETTERS PATENT to Charles Wigg, of Liverpool, in the County of Lancaster,
Alkali Manufacturer, for an invention of "IMPROVEMENTS IN AND IN
"
PROVISIONAL SPECIFICATION left by the said Charles Wigg at the Office
of the Commissioners of Patents on the 14th March 1882.
"
CHARLES WIGG of Liverpool in the County of Lancaster Alkali Manufacturer.
IMPROVEMENTS IN AND IN CONNECTION WITH THE MANUFACTURE OF CHLORINE'
This invention relates to the manufacture of chlorine by the well known Weldon
process and the objects are (a) to cheapen the manufacture by an improved process
for the removal of sulphuric and sulphurous acids from hydrochloric acid and (b) to
utilize the waste chloride of calcium in the production of chlorides of Barium and
Strontium for the purification of the said hydrochloric acid and generally.
It is well known that in the manufacture of chlorine by the Weldon process
there is great loss of manganese through manganese dioxide becoming intermixed
and carried away with sulphate of lime formed in the stills owing to the impurity
of the hydrochloric acid. It is further known that hydrochloric acid free from
sulphuric and sulphurous acids could be advantageously neutralized in the stills or
neutralizing well with manganese dioxide instead of with carbonate of lime in the
neutralizing well and that the loss of manganese dioxide thereby occasioned would
be avoided. Hitherto no means of freeing hydrochloric acid from sulphuric and
sulphurous acids sufficiently cheap and easily available to be of commercial value
in the manufacture of chlorine has been devised.
Now this invention provides means whereby the purification of hydrochloric
acid can be commercially and profitably effected and consists:--
First. In subjecting hydrochloric acid in suitable vats tanks or containers to the
action of chloride of Barium or Strontium obtained substantially as set forth under
the second part, whereby sulphate of Barium or Strontium is formed. The
hydrochloric acid thereby freed from sulphuric acid is removed from the
precipitate by filtration decantation or equivalent means, and the precipitated
[ Price A1

page_text: sulphate of barium or strontium is fuzed with half its weight of chloride of
calcium; a little carbon preferably in the form of small or powdered coal being
added to the mixture near the end of the reaction. Chloride of calcium for the
above reaction is obtained by evaporating the chloride of calcium liquor obtained
as a waste product in the manufacture of chlorine by the Weldon process. The
chloride of Barium or Strontium and sulphate of calcium produced are lixiviated
and the dissolved chloride of barium or strontium decanted, or separated from the
nearly insoluble sulphate of calcium in any convenient manner and is again used
in the purification of hydrochloric acid. The Barium and strontium salts are used
separately or combined.
Second. Chlorides of Burium and Strontium for use as above set forth or generally
are obtained from their sulphates by treatment with chloride of calcium waste
substantially as above set forth for the reconversion of artificial sulphates of Barium
and Strontium into chlorides.
Third. In combination with the process for removing sulphates from hyrochloric
acid set forth under the first part. Sulphurous acid is removed from the said
hydrochloric acid by the addition thereto of a small quantity of manganese dioxide
previous to the treatment with Barium or Strontium chloride.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Charles Wigg in the Great Seal Patent Office on the
14th September 1882.
CHARLES WIGG of Liverpool in the County of Lancaster, Alkali Manufacturer
"IMPROVEMENTS IN AND IN CONNECTION WITH THE MANUFACTURE OF CHLORINE.'
This invention relates to the manufacture of chlorine by the well known Weldon
process and is intended as an adjunct to it. It has for its objects :-
1st. To cheapen the manufacture by an improved method of removing sulphuric
and sulphurous acids from hydrochloric acid and.
2nd. To utilize the waste chloride of calcium that is furnished as a by product
in the Weldons process of manufacturing chlorine for the production of the
chlorides of Barium and Strontium for the purification of the said hydrochloric
acid from sulphuric and sulphurous acids and generally.
It is well known that the greater part of the hydrochloric acid used commercially
for the generation of chlorine is contaminated with sulphuric acid varying in
amount from 25 to 10 per cent and that when such an acid is caused to re-act on
Weldon recovered manganese di-oxide which always contains lime the result is a
copious precipitate of insoluble hydrated sulphate of lime in the gas generator.
Sulphurous acid when present in the acid occasions also the same precipitate as
it is oxidized to sulphuric acid by the nascent chlorine. This precipitate caused
by either impurity or both in falling entangles any unattached manganese dioxide
which may be in suspension in the liquid mixture so that in practice the acid in
the generator cannot be neutralized with manganese dioxide lest some of it should
remain in excess and be lost in the sulphate of lime sludge settled out. Hence
at present the acid is never fully neutralized in the chlorine stills but has to be
neutralized with carbonate of lime after its exit from them, which leads to extra
expenditure for time, material, and acid lost. It is obvious that when a hydro-
chloric acid free from sulphuric and sulphurous acids is employed the above named
disadvantages cannot arise and that the stills can be worked neutral with
manganese di-oxide.
Hitherto no means of removing every trace of sulphuric and sulphurous acids
from hydrochloric acid sufficiently cheap and so really efficient as to be of
commercial value in the manufacture of chlorine has been devised.
Now this invention provides means whereby the sulphur acids may be profitably
removed from hydrochloric acid on a commercial scale and consists.
=
First. In subjecting hydrochloric acid in suitable vats, tanks, or containers
preferably as it flows from the condenser to the action of chloride of Barium or
Strontium in solution whereby a very insoluble sulphate of Barium or Strontium
is formed in accordance with the following equation:-H Cl + H. SO, + Ba Cl₂
3 H Cl + Ba SO. It will be seen that for each equivalent of sulphuric acid
decomposed two equivalents of hydrochloric acid are gained, The baric or strontic
chloride solution contains from two to two and a half pounds of the salt to the
gallon such salt being prepared or obtained substantially as hereinafter setforth.
A convenient method of subjecting the hydrochloric acid to the action of chloride
of Barium or Strontium is to allow a thin stream of the chloride solution to flow
in contact with a stream of hydrochloric acid running from the condenser into a
settling tank. As the tank approaches fullness the workman can easily test from
time to time whether sulphuric acid or chloride of barium or strontium remain in
excess and in the former case he will add more saline solution or in the latter case
more hydrochloric acid, till a sample taken out of the tank and filtered ceases to.

page_text: give a turbidity with either sulphuric acid or the chlorides. Owing to the high
specific gravity of the sulphates of barium and strontium they soon settle out of the
acid and a tank containing several thousand gallons after being well stirred and
left at rest for an hour or two will be ready for decanting off. The turbidity after
that time not amounting to more than 2 or 3 grains of the sulphates of Barium
and Strontium per gallon, filtration is generally totally unnecessary. The total
precipitate occupies very small spaces in the tanks and may be allowed to collect in
the tanks for several days before discharging it from the bottom of them. By having
two or three tanks fitted for the reception of the hydrochloric acid from the towers
adjusted to 12 or 8 hours flow each one or two tanks might be precipitating and
filling while others were discharging. After settling we decant the acid from the
top of the precipitating tanks and run off the precipitated sulphates in the form of
sludge from the bottom. The precipitated sulphates of Barium or Strontium are,
after washing, ready for reconversion into their respective chlorides and can be
used over and over again for the same purpose.
The precipitated sulphate of barium or strontium which is in a finely divided
condition is after washing with water fused with from fifty to ninety per cent. of
its weight of chloride of calcium.
The chloride of calcium necessary for this reaction is furnished as already stated
by the ordinary Weldon method of manganese recovery and usually flows to waste
in a state of solution in water containing about 1/4 lbs. of chloride of calcium
per gallon. An ordinary reverberatory furnace or a crucible shaped iron pot
may be used for effecting the evaporation of the liquor and the subsequent fusion,
but a furnace having a pan shaped bottom of iron or brick work and capable of
being heated from above or below at will suits best. In any case the calcium
liquor is to be evaporated, to dryness and well mixed with the finely powdered
mineral in proper proportions. When the mass has reached dryness the beat is to
be raised until complete igneous fusion of the mixture takes place. During this
stage of the operation the mass is kept constantly stirred, till after the lapse of
some time no more sulphate of barium or of strontium is left undecomposed.
Towards the end of the reaction a small amount of coal or of coal and limestone
may be added according as the insoluble residue of the resulting "melt" is wished
to consist of sulphate or sulphide of calcium, but generally simple fusion with
chloride of calcium only is sufficient. The progress of the decomposition can be
ascertained by the analysis of samples of the mass which may be drawn from the
furnace in a molten condition when no further improvement is manifested.
From the furnace the "melt" is caused preferably to flow on to iron plates
arranged before the front of the furnace where it can cool in the form of thin cakes
or slabs. On exposure to the atmosphere for some time the "melt" falls to pieces
spontaneously owing to the hydration of the chlorides of barium and strontium of
which it contains from 50 to 70%. It is now ready for lixiviation. It is
preferred to lixiviate the "melt' with distilled or other pure water at a
temperature below 35° centigrade in order to dissolve out the contained chlorides
of barium or strontium. The "melt" may be mixed with cinders and being placed
in a long cylindrical vessel be washed by the passage of water through it from
above. As any prolonged contact of the slightly soluble sulphate of lime left as a
residue on lixiviation of the "melt" with the solution of chlorides of barium or
strontium entails loss of the latter and to reverse action it is better to wash in a
more rapid way.
To accomplish this the powdered melt and the requisite amount of water are
placed in a pan provided with mechanical stirrers and the whole charge rapidly
agitated and allowed to settle partially when the supernatant liquor may be forced
up by atmospheric pressure through a filtering medium to a vacuous receiver.
The residue of this operation-sulphate of lime may be applied to any useful
purpose. The chlorides of barium or strontium are reused in the purification of
hydrochloric acid substantially as hereinbefore set forth or if desired they may
be otherwise utilized.

page_text: Second Chlorides of barium or strontium for use as above set forth or generally
are prepared or obtained from their natural or artificial sulphates by the treatment
with chloride of calcium waste substantially as above set forth.
.
Third. In combination with the process for removing sulphuric acids or sulphates
from hydrochloric acid set forth under the first part sulphurous acid or sulphites
are removed from the said hydrochloric acid by the addition thereto of a small
quantity of manganese di-oxide previous to the treatment with barium or
strontium chloride in accordance with the equation 2 H Cl + H. SO, + Mn O₁ =
Mn Cl, H. SO + H₂O.
=
Having now described and particularized my said invention in such manner
that others will be enabled to carry my improvements into effect I claim:-
First. Subjecting hydrochloric acid to the action of chloride of barium or
strontium and reconverting sulphate of barium or strontium into chloride
substantially as specified under the first part for the purposes set forth.
Second. Obtaining chlorides of barium or strontium by the treatment of sulphates
thereof substantially as herein set forth under the second part.
Third. Adding manganese di-oxide to hydrochloric acid previous to subjecting
the same to the action of chloride of barium or strontium substantially in the
manner and for the purpose herein set forth under the third part.
In witness whereof I the said Charles Wigg have hereunto set my hand
and seal this thirteenth day of September in the year of Our Lord one
thousand eight hundred and eighty two.