IMPROVEMENTS IN THE TREATMENT AND UTILIZATION OF CERTAIN FERRUGINOUS SALTS OBTAINED IN PREPARING IRON AND STEEL FOR COATING WITH OTHER METALS."
Year: 1880

page_text: LETTERS PATENT to Frederick Braby, of Fitzroy Works, Euston Road, in
the County of Middlesex, for an Invention of "IMPROVEMENTS IN THE
TREATMENT AND UTILIZATION OF CERTAIN FERRUGINOUS SALTS OBTAINED
IN PREPARING IRON AND STEEL FOR COATING WITH OTHER METALS."
PROVISIONAL SPECIFICATION left by the said Frederick Braby at the
Office of the Commissioners of Patents on the 1st May 1880.
FREDERICK BRADY, of Fitzroy Works, Euston Road, in the County of Middlesex.
IMPROVEMENTS IN THE TREATMENT AND UTILIZATION OF CERTAIN FERRUGINOUS
SALTS OBTAINED IN PREPARING IRON AND STEEL FOR COATING WITH OTHER
METALS."
For rendering the surface of iron or steel adaptable to receive a coating of zinc,
of tin, or of other metals, the acids ordinarily employed for treating the same are
sulphuric acid, muriatic acid, and muriatic acid with some sulphuric acid in it.
The treatment about to be described applies only when muriatic acid alone or
mixed with sulphuric acid is used, and it is assumed that the pickling acid used is
the ordinary commercial muriatic employed very largely in what are commonly
known as galvanizing works.
Galvanized iron so called is iron coated with zinc, and sometimes tin is also so
used as part of the coating. In either case it is usual in the first instance to
immerso the iron, whether wrought or cast, for a certain time (variable according to
the quality and condition of the iron and the strength of the acid) in a bath of hydro-
chloric acid and water, which is rarely if ever quite pure. The scale, any ferrous
and ferric oxides, and other impurities are removed from the iron surfaces, and the
iron, after any subsequent scraping that may be found needful in places, is passed
through a flux of ammoniacal salt into the molten metal with which it is desired
to coat it.
The result of the pickling of the iron in the more or less dilute acid is that hydrogen
gas is evolved, and that a solution of chloride of iron is produced, and this forms
the bulk of the waste wash or "pickle," namely, the partially spent acid, that is
then usually thrown away into the sewers or otherwise. Not only is this ferru-
ginous salt thus entirely wasted, but the disposal of it often leads to complaints
from municipal authorities and from individuals. The object of the present
Invention is to recover the hydrochloric acid in the ferruginous salt, and also to
utilize the iron thereof, for which purpose the waste wash or pickle is treated
with oil of vitriol, which drives out the hydrochloric acid as gas, and converts the
remanent iron into ferrous sulphate, and thus a hitherto waste substance becomes
converted into two useful articles of commerce.

page_text: For effecting the above operation the wasto wash, which still contains some free
acid, is neutralized with scrap iron in a wooden tank lined with gutta percha or india
rubber, or in any other suitable vessel, and is filtered either by passing through a
wooden or other trough with a number of gravity partitions, or by passing it through
gravel or through huckaback or coarse canvas. Or instead of filtering it may bo
decanted after subsidence only. The neutralized fluid is then concentrated by
boiling down to a syrup, and is then treated with the oil of vitriol, or the evapora-
tion may be continued to the formation of the solid green hydrated ferrous chlorido
before the vitrol is added.
But instead of either of these modes of treating the spent acid I prefer to
evaporato it down to dryness, namely, to the white anhydrous solid form. This
can be effected favourably by a reverberatory furnace or by any other ordinary
method.
The dry chloride of iron is then placed in a closed iron or other suitable vessel,
and the oil of vitriol is then gradually added. The delivery of it into the chloride
is effected preferably by distribution over the surface rather than into one portion
of it only. The hydrochloric acid gas that is evolved by the stronger acid taking
possession of the iron of the ferrous chloride is led by a pipe from out of the vessel,
which may be called the mixer or digester, into receiving stone, carthenware, or glass
Woulffe's bottles or carboys containing water, and is there condensed into muriatic
acid ready for sale or use. To ensure as strong an acid as practicable these receivers
should be kept cold. Only a portion of the gas will come over in tho cold, but by
the application of long continued heat and by using sufficient oil of vitriol the
whole of the hydrochloric acid will be liberated.
Anhydrous sulphate of iron remains in the digester. This upon being removed
is treated with the necessary quantity of water to form the green hydrated
copperas of commerce, which is crystallized out by the usual method. By pre-
ference I effect this in the following manner:-When removed from the digester,
and any free sulphuric acid has been neutralized by addition of the needful weight
of scrap iron, preferably in the cold, and in a lead lined vessel (tho progress of the
neutralization being probably aided by galvanic action of the lead lining), the
fluid is then placed in a lead lined tank provided with a lead coil containing
steam of about 40 lbs. pressure and so concentrated. To provide against any small
amount of acid still remaining free a piece of iron may be placed in the tank.
When arrived at the right degree of concentration by evaporation the mass is
removed into shallow lend lined coolers for crystallization, the mother liquor being
afterwards worked up again.
The heated medium that I prefer to employ in the recovery of the hydrochloric
acid is chloride of calcium or paraffin, but the heating can be effected by super-
heated steam or in other known ways. The digester is furnished with a double
chemical or other safety valve. Between the digester and the receiving Woulffo's
bottles or carboys I employ by preference an intermediate washer or purifier for
the purpose of arresting any impurities, such as sulphuric acid, perchloride of iron,
organic substances, and water. This washer may consist of merely a vessel of
water to absorb impurities with muriatic acid, and so when this is saturated to
allow the subsequent receivers to condense the pure gas, or, by preference, it
consists of a dry worm encased in water and terminating in an empty or nearly
empty glass or other vessel, in which impurities fall after passing through the
worm, and the pure gas will be then led from it into the series of receivers charged
with water.
When the original "pickle" contains with it some little sulphuric acid, this is
converted by the action of the iron upon it into sulphate of iron, and comes out in
the natural way at the end of the process as copperas. This indicates the deposit
of any sulphuric acid that may happen to be associated with the muriatic acid, but
there is no claim made in respect of any treatment of such sulphuric acid.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Frederick Braby in the Great Seal Patent Office on the 27th
October 1SS0.
FREDERICK BRABY, of Fitzroy Works, Euston Road, in the County of Middlesex.
"IMPROVEMENTS IN THE TREATMENT AND UTILIZATION OF CERTAIN FERRUGINOUS
SALTS OBTAINED IN PREPARING IRON AND STEEL FOR COATING WITH OTHER
METALS."
For rendering the surface of iron or steel adaptable to receive a coating of zinc,
of tin, or of other metals, the acids ordinarily employed for treating the same are
sulphuric acid, muriatic acid, and muriatic acid with some sulphuric acid in it.
The treatment about to be described applies only when muriatic acid alone or
mixed with sulphuric acid is used, and it is assumed that the pickling acid used is
the ordinary commercial muriatic employed very largely in what are commonly
known as galvanizing works.
Galvanized iron so called is iron coated with zinc, and sometimes tin is also
used as part of the coating. In either case it is usual in the first instance to
immerse the iron, whether wrought or cast, for a cortain time (variable according to
the quality and condition of the iron and the strength of the acid) in a bath of
hydrochloric acid and water, which is rarely, if ever, quite pure. The scale, any
ferrous and ferric oxides, and other impurities are removed from the iron surfaces,
and the iron after any subsequent scraping that may be found needful in places is
passed through a flux usually of ammoniacal salt into the molten metal with
which it is desired to coat it.
The result of the pickling of the iron in the more or less dilute acid is that
hydrogen gas is evolved, and that a solution of chloride of iron is produced, and
this forms the bulk of the waste wash or "pickle," namely, the partially spent acid,
that is then usually thrown away into the sewers or otherwise. Not only is this
ferruginous salt thus entirely wasted, but the disposal of it often leads to complaints
from municipal authorities and from individuals. The object of the present
Invention is to recover the bydrochloric acid in the ferruginous salt, and also to
utilize the iron thereof, for which purpose the waste wash or pickle is treated with
oil of vitriol, which drives out the hydrochloric acid as gas, and converts the
remanent iron into ferrous sulphate, and thus a hitherto waste substance becomes
converted into two useful articles of commerce.
For effecting the above operation the waste wash, which still contains some free
acid, is neutralised with scrap iron in a tank or other suitable vessel, and is filtered
either by passing through a wooden or other trough with a number of gravity
partitions, or by passing it through gravel or through huckaback or coarse canvas.
Or instead of filtering it may be decanted after subsidence only. The neutralized
fluid is then concentrated by boiling down to a syrup, and is then treated with the
oil of vitriol, or the evaporation may be continued to the formation of solid
green bydrated ferrous chloride before the vitriol is added.
But instead of either of these modos of treating the spent acid it may be
evaporated down to dryness, namely, to the white anhydrous solid form. This can
be effected favourably by a reverberatory furnace, or by any other ordinary
method.
The dry chloride of iron is then placed in a closed vessel, and the oil of vitriol
is then gradually added. The delivery of it into the chloride is effected preferably
by distribution over the surface rather than into one portion of it only. The
hydrochloric acid gas that is evolved by the stronger acid taking possession of the
iron of the ferrous chloride is led by a pipe from out of the vessel, which may be
called the mixer or digester, into receiving stone, earthenware, or glass Woulffe's

page_text: bottles or carboys containing water, and is there condensed into muriatic acid
ready for sale or use. To ensure as strong an acid as practicable these receivers
should be kept cold. The tower usually employed for collecting muriatic acid may
be used instead of the Woulffe's bottles. Only a portion of the gas will come over
in the cold, but by the application of long continued heat, and by using sufficient
oil of vitriol the whole of the hydrochloric acid will be liberated.
Sulphate of iron approximately anhydrous remains in the digestor. This upon
being removed is treated with the necessary quantity of water to form the green
hydrated copperas of commerce, which is crystallised by the usual method. By
preference, I effect this in the following manner :-I neutralise any free sulphuric
acid by addition of scrap iron, preferably in the cold, and in a lead lined vessel
(the progress of the neutralisation being probably aided by galvanic action of the
lead lining), the solution is then placed in a tank provided with a steam coil, and
is thus cencentrated. To neutralise any small amount of acid still remaining free,
a piece of iron may be placed in the tank. When arrived at the right degreo of
concentration by evaporation, the mass is removed into shallow coolors for
crystallization, the mother liquor being afterwards worked up again.
The heating medium employed in the recovery of the hydrochloric acid may be
a bath of chloride of calcium or paraffin, but the heating can be effected by super-
heated steam or in other known ways:
Between the digester and the receiving Woulffe's bottles or carboys when these
are employed, I introduce, by preference, an intermediate washer or purifier, for
the purpose of arresting impurities, such as sulphuric acid, perchloride of iron,
organic substances, water, and sulphur compounds. This washer may consist of
merely a vessel of water to absorb impurities along with muriatic acid, and so
when this is saturated to allow the subsequent receivers to condenso the pure gas,
cr, by preference, it consists of a dry worm encased in water, and terminating in
an empty or nearly empty glass or other vessel, in which impuritios fall after
passing through the worm, and the pure gas will be then led from it into the
series of receivers charged with water.
When the original pickle" contains with it some little sulphuric acid, this is
converted by the action of the iron upon it into sulphate of iron, and comes out in
the natural way at the end of the process as copperas. This indicates the deposit
of any sulphuric acid that may happen to be associated with the muriatic acid, but
there is no claim made in respect of any treatment of such sulphuric acid.
Having thus described the nature of my Invention, and in what manner the same
is to be performed I claim,―
The herein described process for the recovery of muriatic acid and production of
sulphate of iron from the waste pickle employed in preparing iron for coating with
other metals.
In witness whereof, I, the said Frederick Braby, have hereunto set my hand
and scal, this Twenty fifth day of October, in the year of our Lord One
thousand
FRED. BRABY. (L.S.)