IMPROVEMENTS IN THE MANUFACTURE OF AMMO- NIACAL SALT AND IN THE PURIFICATION OF GAS
Year: 1884

page_text: ALEXANDER MCDOUGALL of Beech Grove Penrith Esquire I do hereby declare
the nature of my invention for IMPROVEMENTS IN THE MANUFACTURE OF AMMO-
NIACAL SALT AND IN THE PURIFICATION OF GAS and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement :-
My Invention consists in improved methods of producing sulphurous acid and
using it for the neutralisation of aminoniacal liquors and the separation of sulphur
compounds from Gas:
In carrying out my Invention I employ a burner for sulphur or Pyrites which
can be made air-tight.
When this burner is prepared for use, and the charge of sulphur or pyrites
ignited, I cause a current of air from an air-pump or blowing machine to pass into
the burner by which the combustion is sustained. The sulphurous acid thus formed
and the heated air from the burner, I pass into a vessel or cistern containing the
ammoniacal water by which the ammonia is neutralised and the solution
evaporated.
The cistern for this purpose I prefer to have made or lined with lead and to
have it constructed with an inclined underside so that it may be deeper at one end
than at the other. Its dimensions will be determined by the requirements of the
works at which it is used. I place over about two-thirds of its length a perforated
cover, at about six inches from the top and about three inches below the surface of
the liquor.
The sulphurous acid gas and the heated air are made to pass into the liquor,
beneath the perforated cover. The acid combines with the ammonia decomposing
the sulphides and liberating the carbonic acid from the ammonium carbonate,
which passes away with the air through the perforations in the cover. The results"
are the formation of ammonium sulphite and the concentration of the liquor.
As the concentration progresses crystals of ammonium sulphite are formed, and
fall to the bottom towards the deep end of the cistern. These crystals are from
time to time removed from the deep end of the cistern by a perforated scoop or
ladle and placed so that the drainings may flow back into the cistern to be further
evaporated. The crystals on drying are oxidised in the air and become Ammonium
sulphate.

page_text: In the case of the sulphurous acid gas and the heated air being insufficient for
the evaporation of the liquor boat may be applied as occasion may require to assist
the evaporation. Or the neutralised liquor may be removed to evaporating pans
to finish the operations of concentration and crystallisation.
The second part of my Invention consists in employing the liquor containing the
acid ammonium sulphite to wash the gas, by which its sulphur compounds are
decomposed, and the sulphur separated.
The liquor thus used in washing the gas falls back into the well whence it is
again conveyed into the evaporating cistern where it is brought into contact with
the sulphurous acid and neutralised as before.
The sulphur separated from the gas by washing with the ammonium sulphite
settles in the well whence it is removed and used in the burner for the production
of sulphurous acid gas.
The process is thus continuous and self-sustaining.
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed I declare that what
I claim is
I. The use of sulphurous acid produced under pressure by an Air-pump or
blowing machine to neutralise the ammonia in water obtained in the treatment of
coal for the production of gas, and the manufacture of coke.
II. The washing of gas in the acid solution of ammonium sulphite to separato
the ammoniacal and sulphur impurities.
Novemba 95th 1001