IMPROVEMENTS IN THE MANUFACTURE OF SULPHATE AND OTHER SALTS OF ZINC, AND IN CERTAIN APPLICATIONS OF THE SAID SALTS
Year: 1876

page_text: LETTERS PATENT to Roger William Wallace, of the Chemical Works, New
Road, Battersea Park, in the County of Surrey, Manufacturing Chemist, and
Carl Friedrich Claus, of Great St. Helen's, in the City of London, Consulting
Chemist, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE OF
SULPHATE AND OTHER SALTS OF ZINC, AND IN CERTAIN APPLICATIONS OF
THE SAID SALTS."
Sealed the 19th January 1877, and dated the 19th July 1876.
PROVISIONAL SPECIFICATION left by the said Roger William Wallace and
Carl Friedrich Claus at the Office of the Commissioners of Patents on the
19th July 1876.
ROGER WILLIAM WALLACE, of the Chemical Works, New Road, Battersea Park,
in the County of Surrey, Manufacturing Chemist, and CARL FRIEDRICH CLAUS, of
Great St. Helen's, in the City of London, Consulting Chemist. "IMPROVEMENTS IN
THE MANUFACTURE OF SULPHATE AND OTHER SALTS OF ZINC, AND IN CERTAIN
APPLICATIONS OF THE SAID SALTS,"
The object of the present Invention is the manufacture of sulphate of zinc at such
a slight cost as to allow its more general use for purposes for which it is known
to be particularly suited, but from which its present cost of manufacture excludes
it to a great extent, as for instance, for purposes of disinfection, and the like.
The
In order to realize these conditions and to manufacture the said salts at the
lowest possible cost we produce the same from substances which have hitherto been
thrown aside as waste materials, that is to say, we use on the one hand the black
sulphuric acid obtained as a waste product in the refining process of paraffine,
ozokerit, and mineral and other oils, and on the other hand we use as a source of
zinc the refuse of (the so called) galvanizing process known as "skimmings."
former substance, that is to say, sulphuric acid, is so impregnated with tarry matter
and other hydrocarbons as to be quite black and viscid, and in attempting to manu-
facture sulphate of zinc from it in the ordinary process it would be impossible to
separate the salt from the accompanying impurities by simple evaporation and
crystallization. The other substance, known by the term of "skimmings," which

page_text: we use as a source of zinc in this process, consists chiefly of oxide of zinc and
chloride of zinc, a small quantity of chloride of aminonium, and chloride of iron.
Our procedure in relation to the said manufacture (which may be varied in its
details) is as follows:-We place what may be considered an excess of the zinc
compound (in preference in a pulverized form) in a stone tank, or in a wooden tank
lined with stout lead; we then run a corresponding quantity of black acid upon it,
and boil the mixture by means of a steam jet until the acid has become sufficiently
saturated with zinc; we then turn off the steam, allow the liquid to settle a short
time to cause all the solid undissolved particles to subside, and run off the liquid
portions for the boiling down operation. It is impossible to boil down this liquid
in the ordinary way, as owing to the presence of the large quantity of tarry matter
in the impure acid the solution would so rise and foam in the pan as to empty_it
completely of its contents. Another method of boiling, down has therefore to be
resorted to, that is to say, the liquor is run on the bed of a reverberatory furnace
which is divided into two parts. The part farthest from the fire is used as the
boiling down pan, and is built and arranged accordingly. Only about one inch in
depth of the impure sulphate of zinc liquor is run into the furnace at one time, as
otherwise it would so rise as to run out of the furnace. When a sufficient quantity
is boiled down to a thick pasty consistency we ladle the same over upon the part
of the furnace nearest the fire, where the mass is exposed to a high temperature,
thet is to say, a temperature sufficiently high to carbonize or char the tarry or
oleagenous matter contained therein, so that on dissolving the mass in water no
coloring matter is imparted to the solution.
Instead of having the furnace divided and worked as described both operations
may also be carried on upon the same bed, one following the other.
The calcined mass we dissolve by steam in hot or boiling water and obtain a
solution at once sufficiently concentrated for crystallization, but to render it perfectly
clear we filter the same through a shallow tank filter, of which the space below the
filtering surface is furnished with coils of steam pipes to keep the liquor hot and
prevent its crystallizing in the filter, thus choking it up.
In boiling down the liquor and calcining the residuum in the furnace, as above
described, hydrochloric acid is set free, and we convey the same together with the
furnace gases by means of flues and pipes into a condensor and thus condense the
acid to render it innocuous.
Should the solution of zinc obtained from the calcined mass shew the presence of
salts of iron we remove the same as follows:-If they are present in the form of
persalts we add to the liquor previous to it being filtered precipitated oxide or
carbonate of zinc and boil it therewith; by these means the oxide of iron is pre-
cipitated. If however any part of the sulphate of iron contained in the liquor
exists in the form of a protosalt we peroxidize the same by the ordinary means; for
instance, by the use of nitric acid or chlorine, and then precipitate it by means of
oxide or carbonate of zinc.
We proceed in the manufacture of chloride of zinc in a similar manner to that
described in reference to the manufacture of sulphate of zinc, freeing it from the
presence of iron by means of the oxide or carbonate of zinc.
When using the salts of zinc thus obtained for disinfecting purposes we propose
to add varying proportions of sulphate of magnesia, and to the chloride of zinc
varying proportions of chloride of magnesium.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Roger William Wallace and Carl Friedrich Claus in the Great Seal
Patent Office on the 19th January 1877.
ROGER WILLIAM WALLACE, of the Chemical Works, New Road, Battersea Park,
in the County of Surrey, Manufacturing Chemist, and CARI. FRIEDRICH CLAUS, of

page_text: "
Great St. Helen's, in the City of London, Consulting Chemist. IMPROVEMENTS IN
THE MANUFACTURE OF SULPHATE AND OTHER SALTS OF ZINC, AND IN CERTAIN
APPLICATIONS OF THE SAID SALTS."
The object of the present Invention is the manufacture of sulphate of zinc at
such a slight cost as to allow its more general use for purposes for which it is known
to be particularly suited, but from which its present cost of manufacture excludes
it to a great extent, as for instance, for purposes of disinfection, and the like.
In order to realize these conditions and to manufacture the said salts at the
lowest possible cost we produce the same from substances which have hitherto been
thrown aside as waste materials; that is to say, we use on the one hand the black
sulphuric acid obtained as a waste product in the refining process of paraffin,
ozokerit, and mineral and other oils; and on the other hand we use as a source of
zinc the refuse of (the so called) galvanizing process known as "skimmings." The
former substance, that is to say, sulphuric acid, is so impregnated with tarry matter
and other hydrocarbons as to be quite black and viscid, and in attempting to manu-
facture sulphate of zinc from it in the ordinary process it would be impossible to
separate the salt from the accompanying impurities by simple evaporation and
crystallization. The other substance, known by the term of "skimmings," which I
use as a source of zinc in this process consists chiefly of oxide of zinc and chloride
of zinc, a small quantity of chloride of ammonium, and chloride of iron.
Our procedure in relation to the said manufacture (which may be varied in its
details) is as follows:-We place what may be considered an excess of the zinc
compound (in preference in a pulverized form) in a stone tank, or in a wooden tank
lined with stout lead; we then run a corresponding quantity of black acid upon it
and boil the mixture by means of a steam jet until the acid has become sufficiently
saturated with zinc; we then turn off the steam, allow the liquid to settle a short
time to cause all the solid undissolved particles to subside, and run off the liquid
portion for the boiling down operation. It is impossible to boil down this liquid in
the ordinary way, as owing to the presence of the large quantity of tarry matter in
the impure acid the solution would so rise and foam in the pan as to empty it
completely of its contents. Another method of boiling down has therefore to be
resorted to, that is to say, the liquor is run on the bed of a reverberatory furnace
which is divided into two parts. The part farthest from the fire is used as the
boiling down pan, and is built and arranged accordingly. Only about one inch in
depth of the impure sulphate of zinc liquor is run into the furnace at one time, as
otherwise it would so rise as to run out of the furnace. When a sufficient quantity
is boiled down to a thick pasty consistency we ladle the same over upon the part of
the furnace nearest to the fire, where the mass is exposed to a higher temperature,
that is to say, a temperature sufficiently high to carbonize or char the tarry or
oleaginous matter contained therein, so that on dissolving the mass in water no
coloring matter is imparted to the solution.
Instead of having the furnace divided and worked as described both operations
may also be carried on upon the same bed, one following the other.
The calcined mass we dissolve by steam in hot or boiling water, and obtain a
solution at once sufficiently concentrated for crystallization, but to render it perfectly
clear we filter the same through a shallow tank filter of which the space below the
filtering surface is furnished with coils of steam pipes to keep the liquor hot and
prevent its crystallizing in the filter, thus choking it up.
In boiling down the liquor and calcining the residuum in the furnace, as above
described, hydrochloric acid is set free, and we convey the same together with the
furnace gases by means of flues and pipes into a condenser, and thus condense the
acid to render it innocuous.
Should the solution of zinc obtained from the calcined mass show the presence of
salts of iron we remove the same as follows:-If they are present in the form of
persalts we add to the liquor previous to it being filtered precipitated oxide or
carbonate of zinc and boil it therewith; by these means the oxide of iron is pre-
cipitated. If however any part of the sulphate of iron contained in the liquor exists

page_text: in the form of a protosalt we peroxidize the same by the ordinary means; for
instance, by the use of nitric acid or chlorine, and then precipitate it by means of
oxide or carbonate of zinc.
We proceed in the manufacture of chloride of zinc in a similar manner to that
described in reference to the manufacture of sulphate of zinc, freeing it from the
presence of iron by means of the oxide or carbonate of zinc.
When using the salts of zinc thus obtained for disinfecting purposes we propose
to add to the sulphate of zinc varying proportions of sulphate of magnesia, and to
the chloride of zinc varying proportions of chloride of magnesium.
Having thus fully described our said. Invention, and shown how the same may
be conveniently and advantageously carried into practise, we wish it understood
that we claim,-
First. The production of white merchantable sulphate of zinc by a process which
consists in dissolving oxides or other compounds of zinc in black tarry sulphuric
acid obtained as a waste product, and boiling down and charring or calcining the
impure salts, as above described.
Second. The purification of solutions of salts of zinc containing iron by means of
precipitated carbonate or oxide of zinc, as above described.
Third. The combination of the above specified salts of zinc with the sulphate or
the chloride of magnesium, for the purpose set forth.
In witness whereof, I, the said Carl Friedrich Claus, for myself and on behalf
of the said Roger William Wallace, have hereunto set my hand and seal,
this Nineteenth day of January, in the year of our Lord One thousand
eight hundred and seventy-seven.
C. F. CLAUS.
(L.S.)