Year: 1886

page_text: Date of Application, 22nd June, 1886.
Complete Left, 22nd Mar., 1887.
Complete Accepted, 22nd Apr., 1887.
DECED
We JAMES HAWKE DENNIS of No. 19 Castle Street Liverpool in the County of
Lancaster, Merchant and NICHOLAS GLENDINNING of Saint Helens in the County
of Lancaster, Works Manager, do hereby declare the nature of this invention
to be as follows:-
The object is to obtain commercially pure zinc sulphide from solutions containing
zinc salts such as are produced in the manufacture of copper by the wet process, and
in other metalurgical chemical and manufacturing operations.
The invention relates first to solutions containing zinc and also metallic salts capable
of precipitation by sulphuretted hydrogen in the presence of free acid, and second to
solutions in which such salts are absent.
The invention consists First in obtaining solutions in the condition second above
mentioned by treating the first above mentioned solutions with sulphuretted hydrogen
in the presence of free acid until the metals capable of precipitation are removed from
solution, care being taken to have sufficient free acid present to prevent precipitation
of the zinc.
Second in treating solutions in the condition second above mentioned with carbonate
of lime in any convenient form until free acid is neutralized or nearly so, the liquor
is then filtered and subjected to the action of sulphuretted hydrogen to precipitate the
the zinc, care being taken that the solution is sufficiently dilute to allow of the zinc
being precipitated before the said solution is rendered sufficiently acid by the action of
the sulphuretted hydrogen to prevent the precipitation of the zinc. Instead of
diluting, the liquid may be filtered after the sulphuretted hydrogen ceases to cause
precipitation of the zinc and the filtrate again neutralized and the treatment by
sulphuretted hydrogen repeated.
The precipitated zinc sulphide is separated from the solution by filtration, is washed
first with slightly acidulated water then with ordinarily pure water and finally dried
in any convenient way.
T 1
1
AT

page_text: COMPLETE SPECIFICATION.
Improvements in Obtaining Sulphide of Zinc from Solutions.
We JAMES HAWKE DENNIS of 19 Castle Street Liverpool, in the County of Lan-
caster, Merchant and NICHOLAS GLENDINNING of Saint Helens in the County of
Lancaster, Works Manager 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:-
The object is to obtain commercially pure zinc sulphide from solutions containing.
zinc salts such as are produced in the manufacture of copper by the wet process and in
other metallurgical chemical and manufacturing operations.
The invention relates first to solutions containing zinc and also metallic salts capable
of precipitation by sulphuretted hydrogen in the presence of free acid, and second to
solutions in which such salts are absent.
The invention consists, First in obtaining solutions in the condition second above
mentioned by treating the first above mentioned solutions with sulphuretted hydrogen
in the presence of free acid until the metals capable of precipitation are removed from
solution care being taken to have sufficient free acid present to prevent precipitation
of the zinc.
Second. In treating solutions in the condition second above mentioned with carbonate
of lime in any convenient form until free acid is neutralized or nearly so, the liquor is
then filtered and subjected to the action of sulphuretted hydrogen to precipitate the
zinc care being taken that the solution is sufficiently dilute to allow of the zinc being
precipitated before the said solution is rendered sufficiently acid by the action of the
sulphuretted hydrogen to prevent the precipitation of the zinc: Instead of diluting,
the liquid may be filtered after the sulphuretted hydrogen ceases to cause precipitation
of the zinc and the filtrate again neutralized and the treatment by sulphuretted hydrogen
repeated.
The precipitated zinc sulphide is separated from the solution by filtration, is washed
first with slightly acidulated water, then with ordinarily pure water and finally dried in
any convenient way.
The solutions first above mentioned which contain metallic salts such as salts of
copper which in the presence of free acid are precipitated by sulphuretted hydrogen,
are subjected to the action of sulphuretted hydrogen in any suitable or well known
manner until the said metallic salts are precipitated and until the said sulphuretted
hydrogen is slightly in excess. The quantity of free acid need not exceed one half of
one per cent.
The precipitate is allowed to subside and the clear liquor decanted, run off or other-
wise separated therefrom as may be found convenient.
The solution second above mentioned and the decanted or separated solutions above
set forth are passed through a filter bed of limestone or suitable carbonate of lime in
small pieces until the solutions are neutralized or nearly so, it being preferred to have
a trace of free acid.

page_text: Or the solutions may be neutralized by admixture with carbonate of lime and after-
wards cleared by filtration. The clear neutralized solutions are then if they contain more
than from ten to eleven ounces of zinc to the cubic foot reduced by the addition of
water to that strongth and are subjected to the action of sulphuretted hydrogen until
the zinc is precipitated as sulphide when it is separated from the filtrate in any
convenient manner.
"
Instead of diluting the solutions as above set forth they may be subjected to the
action of sulphuretted hydrogen until as much zinc as can be is.precipitated-the
precipitate is then separated from the filtrate, the filtrate is neutralized and filtered in
the manner above set forth and again subjected to the action of sulphuretted hydrogen
and this process is repeated until all the zinc obtainable is precipitated.
The precipitation of the zinc is advantageously conducted in a vessel provided with
an agitator and close fitting cover. The vessel is filled with the zine solution and
then connected to the holder or generator of sulphuretted hydrogen after which a
quantity of the solution is run off and replaced by sulphuretted hydrogen, agitation is
commenced and continued until the zinc has been precipitated. The atmosphere of
sulphuretted hydrogen in the vessel is displaced by water after the operation has been
completed.
The zinc sulphide obtained is placed in covered filtering vessels connected with a
chimney or other aspirator and is washed with water containing a trace of free acid
until the iron and other salts are removed. The washing is then completed with
water.
The zinc sulphide is pressed dried and dehydrated in any convenient manner.
By free acid we mean such acids as are usually met with in the manufacture of
copper by the wet process and like metallurgical, chemical and manufacturing
operations.
Having now particularly described and ascertained the nature of the said invention
and in what manner the same is to be performed, we declare that what we claim is :-
First Treating solutions containing zinc and also metallic salts capable of precipi-
tation in the presence of free acid substantially in the manner and for the purpose
herein set forth.
Second-Treating solutions containing zinc and not containing metallic salts capable
of precipitation by sulphuretted hydrogen in the presence of free acid substantially in
the manner and for the purpose set forth.
Third The treatment for obtaining zinc sulphide of the solutions herein specified
substantially in the manner set forth.
Dated this 31
M
1. 1005