IMPROVEMENTS IN TREATING AND UTILISING WASTE ACID LIQUORS
Year: 1868

page_text: LETTERS PATENT to Napier Smith, of Glasgow, in the County of
Lanark, North Britain, for the Invention of "IMPROVEMENTS IN
TREATING AND UTILISING WASTE ACID LIQUORS."
Sealed the 9th April 1869, and dated the 12th October 1868.
PROVISIONAL SPECIFICATION left by the said Napier Smith at the
Office of the Commissioners of Patents, with his Petition, on the
12th October 1868.
I, NAPIER SMITH, of Glasgow, in the County of Lanark, North Britain,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
TREATING AND UTILISING WASTE ACID LIQUORS," to be as follows, that is to
say:
This Invention has for its object the obtaining of valuable products
from waste acid liquors, such as are obtained in galvanising works. The
acid used for "pickling" or cleaning iron to prepare it for galvanising
when too weak to be further used in that way is saturated with iron if
still containing any free acid, and there is then added to it as much lime

page_text: as will precipitate the iron. The precipitate is drained, washed, dried,
and burned in a suitable furnace, and if necessary again washed and
dried. The resulting product is oxide of iron in a convenient form for
commercial purposes. For the lime may be substituted any alkaline
earth, alkali, or carbonate thereof, or any mixture, such as "soapers'
waste" containing one or more of them.
The solution of chloride of calcium drained from the precipitated iron
when hydrochloric acid has been used is, by a second part of the Inven-
tion, mixed with an equivalent proportion of sulphate of ammonia. The
resulting products are sulphate of lime which is precipitated, and may
be washed and used like ordinary sulphate of lime and chloride of
ammonium in solution, which may be concentrated and crystalised in
the ordinary way. This second part of the Invention is applicable to
waste chloride of calcium obtained in various ways, and also when more
or less impure.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Napier Smith in the Great Seal Patent Office on
the 10th April 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, NAPIER
SMITH, of Glasgow, in the County of Lanark, North Britain, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twelfth day of October, in the year
of our Lord One thousand eight hundred and sixty-eight, in the thirty-
second year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Napier Smith, Her special licence
that I, the said Napier Smith, my executors, administrators, and assigns,
or such others as I, the said Napier Smith, my executors, adminis-
trators, and assigns, should at any time agree with, and no others,
from time to time and at all times thereafter during the term therein
expressed, should and lawfully might make, use, exercise, and vend,
within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN TREATING
AND UTILISING WASTE ACID LIQUORS," upon the condition (amongst others)
that I, the said Napier Smith, my executors or administrators, by an

page_text: instrument in writing under my, or their, or one of their hands and
seals, should particularly describe and ascertain the nature of the said
Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Napier Smith, do hereby declare
the nature of my said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and
by the following statement in writing, that is to say :-
My said Invention has for its object the obtaining of valuable products
from waste acid liquors, such as are obtained in galvanising works; and
it is most advantageously applicable to the hydrochloric acid used for
"pickling" or cleaning iron to prepare it for galvanising. When this
acid is too weak to be further used in that way I saturate it with iron,
by preference in the form of sheet scrap, if it still contains any free acid,
and I then add to it as much lime mixed with water as will precipitate
the iron, the quantity of lime being in each case ascertainable by well-
known chemical tests. The precipitate is drained, washed, dried, and
burned in a suitable furnace, and if necessary again washed and dried.
The resulting product is oxide of iron in a convenient form for com-
mercial purposes and suitable for a pigment or otherwise. The process
may be modified by omitting the burning, when the dried product will
be a different preparation of iron, usable as a pigment, giving a different
shade or otherwise. Or the precipitate may be simply drained and be
then mixed with sawdust or other suitable material for the purpose of
being used in a well-known manner for purifying illuminating gas. For
the lime may be substituted any alkaline earth, alkali, or carbonate
thereof, or any mixture such as "soapers' waste," containing one or
more of them.
The solution of chloride of calcium drained from the precipitated iron
is, by a second part of my Invention, mixed with an equivalent proportion
of sulphate of ammonia. The resulting products are sulphate of lime,
which is precipitated and may be washed and used like ordinary sulphate
of lime, and chloride of ammonium in solution which may be con-
centrated and crystalised in the ordinary way. This second part of my
Invention is applicable to waste chloride of calcium obtained in various
ways, and also when more or less impure.

page_text: Having thus particularly described my said Invention, and the manner
in which the same is to be performed, I have to state that what I believe
to be novel and original, and claim as the Invention secured to me by
the herein-before in part recited Letters Patent is,-
1. The treating and utilising of waste hydrochloric acid containing
iron by precipitating the iron with an alkali, or alkaline earth, or
carbonate, and drying or burning it, substantially as herein-before
described.
And, 2. The utilising of chloride of calcium obtained in separating the
iron, or otherwise by adding sulphate of ammonia, so as to obtain
sulphate of lime and chloride of ammonium, substantially as herein-
before described.
In witness whereof, I, the said Napier Smith, have hereunto sot
my hand and seal, this Ninth day of April, in the year of our
Lord One thousand eight hundred and sixty-nine.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
NAPIER SMITH. (L.S.)