Παμτοντα from Sulphates and Bisulphates.
Year: 1886

page_text: Date of Application, 10th Apr., 1886.
Complete Left, 10th Jan., 1887.
Complete Accepted, 11th Feb., 1887.
Παμτοντα
from Sulphates and Bisulphates.
I, JOHN HENRY JOHNSON of 47 Lincoln's Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of this invention :-
This Invention relates to a process based on the reaction which results when an
acid sulphate is calcined with a reducing agent such as charcoal, coal, sawdusi, coke,
far or other substances possessing similar chemical properties.
In applying this principle to the treatment of acid alkaline sulphates heated to
about redness the sulphuric acid in excess is decomposed with the production of
sulphurous acid and the neutral sulphate remaining does not contain any sulphuret
even when an excess of the reducing agent is employed. In this case the reaction
may be effected in a wrought or cast iron vessel. Theoretically a minimum of about
one and a half equivalents of carbon to one equivalent of bisulphate of soda or of
potash is suitable but in practice the proportion of carbon is somewhat greater and
the carbon is pulverised more finely in proportion to the degree of purity desired in
the product. In place of causing the carbon to act upon the bisulphate separately it
is often advantageous to mix it beforehand with the materials whose reaction is
employed to produce the bisulphate. For example by adding the carbon to the
mixtures of sulphuric acid and alkaline chlorides employed in the preparation of
hydrochloric acid and which leave hisulphates as residues neutral sulphates may be
directly obtained.
The sulphuric acid first drives off the hydrochloric acid and afterwards when the
latter has almost disappeared the excess of sulphuric acid escapes in its turn forming
sulphurous and carbonic acids which are not readily soluble in liquid hydrochloric
acid and which on leaving the apparatus for condensing the latter may be conducted
to lead chambers to be converted into sulphuric acid or be otherwise utilised by
known means.
The liberation of the sulphuric acid favours the removal of the

page_text: remaining hydrochloric acid and when this is the sole result in view less than the
theoretical minimum of carbon may be employed. It is often advantageous to add
carbon to the mixtures of alkaline nitrates, and sulphuric acid employed in the
manufacture of nitric acid or of products of the decomposition of this acid and
valuable results are obtained by the introduction of carbon into the nitrate vessels
which supply nitrous and nitric acid gases to the lead chambers in order to produce
sulphuric acid therein.
For this purpose from eight to ten per cent of pulverised coal or coal dust passed
through a No. 100 sieve and mixed with the nitrate of soda is employed. The
sulphuric acid is afterwards added in the usual proportions. The carbon may be
added at will to the acid alone or to the mixture of acid and salt. The excess of
coal is burned or consumed after the reaction and in place of a bisulphate which
poisons the air with its acid vapours a sulphate is taken out of the vessel when cool
which is neutral, white and porous and is of great commercial value especially for
glass manufacturers. At the same time the sulphuric acid driven off by the carbon
and reformed by oxidation is collected in the chambers. Moreover the vessels are
less liable to corrosion and less nitrate is consumed probably because the nitric acid
partially deoxidised and mixed with foreign gases is naturally more difficult to
condense.
This Invention is also applicable when an alkaling sulphuret is to be obtained
as the ultimate product by raising the temperature and introducing an extra
quantity of carbon the products being treated in a reverberatory furnace or in pots
or vessels of cylindrical or other form made of clay or other suitable materials.
J. HENRY JOHNSON,
47, Lincoln's Inn Fields, London, W.C.

page_text: Improved Process or Means for Expelling Sulphuric Acid in Excess
from Sulphates and Bisulphates.
JOHN HENRY JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman, a communication from Jacques Louis Kessler of Clermont Ferrand,
Puy de Dome in the Republic of France, 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 relates to a process based on the reaction which results when an
acid sulphate is calcined with a reducing Agent such a charcoal coal, wood sawdust,
coke, tar or other substances possessing similar chemical properties.
In applying this principle to the treatment of acid alkaline sulphates heated until
they commence to redden, the sulphuric acid in excess or super saturating is alone
decomposed with the production of sulphurous acid and there remains a neutral
sulphate not containing any sulphuret even when an excess of the reducing Agent
is employed. In this case the reaction may be effected in a wrought or cast iron
vessel.
If the materials be heated to a bright red or white heat the excess of reducing
agent re-acts upon the neutral sulphate also and converts it into a sulphuret. As this
sulphuret attacks iron it is necessary to take precautions to protect the surfaces of
the vessels when made of iron from direct contact therewith or preferably to conduct
the operation in an apparatus made of earthenware or brickwork such as a
reverberatory furnace or retort or crucible.
Theoretically when it is desired to eliminate only the excess of sulphuric acid in
the bisulphate a minimum or about one and a half equivalents (or about nine parts
by weight) of carbon to one equivalent (or about one hundred and eleven parts by
weight) of bisulphate of soda or of potash (about 127-11 parts by weight) is suitable.
When it is desired to obtain the aforesaid conversion into sulphuret the minimum of
carbon is about five and a half equivalents or about thirty three parts by weight to
one of the aforesaid equivalents of either bisulphate.
In practice the proportion of carbon is preferably somewhat greater unless it be
necessary to avoid its presence in the final product. These proportions are merely
given as a guide and may be modified according to the quantity of free acid in excess
and other conditions.
In obtaining sulphurets a large excess of carbon which may be subsequently utilized
affords protection against the excessive fusion and corrosion of the calcining vessel or
chamber.
In place of causing the carbon to act immediately upon the bisulphate, it is often
advantageous to mix it beforehand with the materials whose reaction is employed to
produce the bisulphate. For example the neutral sulphates may be obtained by
adding the carbon to the mixtures of sulphuric acid and alkaline chlorides (chlorides

page_text: of sodium or potassium) employed in the preparation of hydrochloric acid and which
leave bisulphates as residues.
The sulphuric acid first drives off the hydrochloric acid and afterwards when the
latter has almost disappeared the excess of sulphuric acid escapes in its turn forming
less readily soluble sulphurous and carbonic acids which by a suitable washing by
known means are enabled to be carried beyond the apparatus for condensing the
hydrochloric acid and utilized as required. The sulphurous acid mixed with carbonic
acid may be conducted to the lead chambers wherein sulphuric acid is prepared in
order to increase the yield for example.
The effect of the addition of a reducing agent such as carbon is not confined to
the production of neutral sulphates or sulphurets. The sulphurous acid thus produced
drives off the volatile constituents more rapidly, at a lower temperature and with
less injury to the apparatus. The carbon may be employed according to this
invention in smaller proportions than the theoretically minimum quantity hereinbefore
specified.
In the manufacture of nitric acid or of the products of its decomposition or
separation it is sometimes advantageous to add carbon to the mixture of alkaline
nitrate and sulphuric acid and the invention also relates to its employment in the
nitrate vessels which supply the nitric acid required in the manufacture of sulphuric
acid in leaden chambers.
With this object from about eight to ten per cent of pulverised coal or coal dust
passed through a No. "100 sieve can be employed with advantage being mixed with
the nitrate of soda to which sulphuric acid is added in the usual proportions. The
excess of coal is burned or consumed after the reaction and in place of a bisulphate
which poisons the atmosphere with its acid vapours, a sulphate is taken out of the
vessel when cool which is neutral, white and friable and is of great commercial value
especially for glass manufacturers.
The consumption of nitrate is less than when the carbon is omitted the whole of
the excess of acid in the bisulphate is recovered and the vessels are less carroded.
It is frequently advantageous to add carbon in order to drive off the excess of
sulphuric acid not only from alkaline sulphates but sulphates of alumina and
the like. A small quantity of carbon mixed with the clay or bauxite before or after
the addition of the sulphuric acid accelerates the removal of the excess of the latter
in the reverberatory furnace and leaves the sulphate of alumina produced more
soluble.
Having now particularly described and ascertained the nature of the said invention
and in what manner the same is to be performed I declare that what I claim is.
The improved process or means for expelling the sulphuric acid in excess from
sulphates and bisulphates consisting essentially in the employment of a reducing
agent such as charcoal coal, or carbon, coke, tan sawdust or the like and an elevated
temperature substantially as herein before described.
J. HENKY JOHNSON,.
Agent.