Year: 1886

page_text: Date of Application, 31st Mar., 1886.
Complete Left, 23rd Dec., 1886.
Complete Accepted, 25th Jan., 1887.
I, WILLIAM STEVENS SQUIRE of Clarendon House St. Johns Wood Park in the
County of Middlesex, Chemical Engineer, do hereby declare the nature of this inven-
tion to be as follows:-
In certain voltaic batteries, such as are described in the Specifications No. 1464 of
1882 and No. 4475 of 1884 in which solution of caustic potash or soda is used as
exciting liquid and zinc as one of the elements, the spent liquid consists chiefly of a
combination of potash or soda and oxide of zinc, forming what may be termed zincate
of potash or soda. My invention relates to a process for treating this liquid so as to
restore the potash or soda in condition for subsequent use, and to obtain zinc com-
pounds that can be applied in the arts or manufactures. For this purpose, I effect a
reaction by means of sulphuretted hydrogen so as to obtain impure zinc sulphide as a
precipitate and solution of caustic potash or soda as supernatant liquid. This reaction
may be effected directly by passing the sulphuretted hydrogen through the spent
liquid of the battery, preferably keeping the liquid in agitation so as to break the thin
shells of zinc sulphide which tend to form around the bubbles of sulphuretted
hydrogen. Or the reaction may be effected indirectly, by passing sulphuretted
hydrogen through a solution of caustic potash or soda thereby transforming it into
potassium or sodium sulphide, and then mixing this solution with the spent liquid of
the battery, causing precipitation of impure zinc sulphide. In either case the liquid,
separated by decanting and filtering, is solution of caustic potash or soda ready for
subsequent use, and the precipitate, impure zinc sulphide, is dissolved in hydrochloric
acid or sulphuric acid, whereby sulphuretted hydrogen is evolved, and this is at once
applied, as above described, to the treatment of spent liquid, or is stored for subsequent
use in this way. When hydrochloric acid is used as the solvent of the zinc sulphide,
the liquid produced is zinc chloride that can be purified and used for disinfecting or
other purposes. When sulphuric acid is employed as the solvent, the liquid produced
is solution of zinc sulphate which may also be purified and used for various purposes.
I find it advantageous however to produce from the purified chloride or sulphate of
zinc a useful pigment by adding to it barium sulphide. When the chloride is thus
treated, zinc sulphide is precipitated; when the sulphate is thus treated, a mixed
precipitate of zinc sulphide and sulphate of barium is produced.
ABEL & IMKAY,
28, Southampton Buildings, London, W.C.,
Agents for the Applicant.

page_text: A Process for Utilising the Spent Liquid from Certain voltaic
Batteries.
I, WILLIAM STEVENS SQUIRE, of Clarendon House, St. John's Wood Park in the
County of Middlesex, Chemical Engineer, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :-
In certain voltaic batteries such as are described in the specifications No. 1464 of
1882 and No. 4475 of 1884, in which solution of caustic potash or soda is used as
exciting liquid and zinc as one of the elements, the spent liquid consists chiefly of a
combination of potash or soda and oxide of zinc forming what may be termed zincate
of potash or soda. My invention relates to a process for treating this liquid so as to
restore the potash or soda in condition for subsequent use and to obtain zinc com-
pounds that can be applied in the arts or manufactures. For this purpose I effect a
reaction by means of sulphuretted hydrogen so as to obtain impure zinc sulphido as a
precipitate and solution of caustic potash or soda as supernatant liquid. This reaction
may be effected directly by passing the sulphuretted hydrogen through the spent liquid
of the battery, preferably keeping the liquid in agitation so as to break the thin shells
of zinc sulphide which tend to form around the bubbles of sulphuretted hydrogen. Or
the reaction may be effected indirectly by passing sulphuretted hydrogen through a
solution of caustic potash or soda, thereby transforming it into potassium or sodium
sulphide, and then mixing this solution with the spent liquid of the battery, causing
precipitation of impure zinc sulphide. In either case, the liquid, separated by
decanting and filtering, is solution of caustic potash or soda ready for subsequent use,
and the precipitate, impure zinc sulphido, is dissolved in hydrochloric acid or sulphuric
acid, whereby sulphuretted hydrogen is evolved and this is at once applied as above
described to the treatment of spent liquid, or is stored for subsequent use in this way.
When hydrochloric acid is used as the solvent of the zine sulphide, the liquid produced
is zinc chloride that can be purified and used for disinfecting or other purposes. When
sulphuric acid is employed as the solvent, the liquid produced is solution of zinc
sulphate, which may also be purified and used for various purposes. I find it
advantageous however to produce from the purified chloride or sulphate of zinc a
useful pigment by adding to it barium sulphide. When the chloride is thus treated,
zinc sulphide is precipitated; when the sulphate is thus treated, a mixed precipitate of
zine sulphide and barium sulphate is produced.
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 :-
The herein described process for treating the spent liquid from a voltaic battery in
which caustic alkali is used as exciting liquid and zinc as one of the elements, the said
process consisting of the following steps, namely, subjecting the liquid to the action of
sulphuretted hydrogen either directly or indirectly as described, thereby recovering
solution of caustic alkali and precipitating zinc sulphide; treating as described the
zinc sulphide thus precipitated with acid to produce a zinc salt and to reproduce
sulphuretted hydrogen for use in the manner above referred to; and treating as des-
cribed the zinc salt thus produced with barium sulphide for the production of pigments.
ABEL & IMRAY,