Improvements in the Treatment of Alkali Waste for the Production of Sulphuretted Hydrogen.
Year: 1890

page_text: Date of Application, 9th June, 1890
Complete Specification Left, 9th Mar., 1891-Accepted, 9th May, 1891
PROVISIONAL SPECIFICATION.
Improvements in the Treatment of Alkali Waste for the Production
of Sulphuretted Hydrogen.
We, RICHARD HOLDEN DAVIDSON, and RICHARD HOLDEN DAVIS, both of
Widnes, in the County of Lancaster, Chemical Manufacturers, do hereby declare
the nature of this invention to be as follows:-
In working the Chance sulphur recovery process there are always present in the
liquors more or less sodium compounds, which, by the action of H2S and CO₂
(sulphuretted hydrogen and carbonic acid) form sulphydrate of soda. This
compound, when present in any considerable quantity, interferes with the working
of the process, and this invention has for its object the decomposition of all such
sodium compounds.
We find that by the addition of a certain quantity of CaCl, (calcium chloride)
(easily determined by an analysis of the waste) the carbonate of soda originally
present in the waste and afterwards formed during the working of the process by
the action of the CO, upon the sodium hydrate, silicate and aluminate, is immediately
decomposed into NaCl (sodium chloride) CaCO3 (calcium carbonate) being
precipitated. The amount of calcium chloride which it is necessary to use varics
according to circumstances, but the amount added must be sufficient to decompose
the soda salts.
The final residue after being so purified is free from soda, and consists mainly of
carbonate of lime, and is found to be very suitable for neutralising still liquors of
the Weldon chlorine process.
Dated this 7th dor of Iun 1000
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Patent Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in the Treatment of Alkali Waste for the Production
of Sulphuretted Hydrogen.
We, RICHARD HOLDEN DAVIDSON and RICHARD HOLDEN DAVIS both of
Widnes in the County of Lancaster, Chemical Manufacturers, 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:-
In working the Chance sulphur recovery process there are always present in the
liquors more or less sodium compounds, which, by the action of CO, and H,S,
(carbonic acid and sulphuretted hydrogen) form sulphydrate of soda. This
compound, when present in any considerable quantity, interferes with the perfect
working of the process, having an injurious effect upon the regularity of the
strength of H2S given off, and also causing considerable trouble in freeing the final
liquors from the last traces of sulphides, and this invention has for its object the
decomposition of all such deleterious sodium compounds, and the formation of an
innocuous one, sodium chloride.
We find that by the addition of a certain quantity of CaCl, (calcium chloride
to the waste cream, (easily determined by an analysis of the waste,) the carbonate
of soda, originally present in the waste and afterwards formed during the working
of the process by the action of the CO, upon the sodium hydrate, silicate and
aluminate, is immediately decomposed into NaCl (sodium chloride), CaCO, (calcium
C

page_text: carbonate) being precipitated.
The amount of calcium chloride which it is
necessary to use varies according to circumstances, but the amount added must be
sufficient to decompose the soda salts.
It will be found that after this decomposition of the soda compounds, the strength
of the HS given off in the Chance process will be more uniform, and there will
be much less difficulty in freeing the liquors from the last traces of sulphides.
The final residue, after the Chance process has been performed being so purified,
is free from soda and consists mainly of carbonate of lime, and is found to be very
suitable for neutralising still liquors of the Weldon chlorine process.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is
The addition of an alkaline earth chloride to the liquors or waste used in the
Chance or other equivalent process of treating waste, whereby the soda compounds
which, during the working of the process, would otherwise have a tendency to form
sulphydrate of soda are decomposed.
Dabad thin 7th d... af al 1001
WM. P. THOMPSON & Co.,
Of Liverpool, Manchester, Nottingham, and London, Patent Agents.