IMPROVEMENTS IN OBTAINING USEFUL PRODUCTS FROM CERTAIN MATERIALS PRODUCED IN THE PROCESS OF GALVANISING OR COATING IRON WITH ZINC
Year: 1867

page_text: LETTERS PATENT to Charles Crockford, of Holywell, in the County of
Flint, Gentleman, for the Invention of "IMPROVEMENTS IN OBTAINING
USEFUL PRODUCTS FROM CERTAIN MATERIALS PRODUCED IN THE PROCESS OF
GALVANISING OR COATING IRON WITH ZINC."
Sealed the Sth October 1867, and dated the 13th April 1867.
PROVISIONAL SPECIFICATION left by the said Charles Crockford at
the Office of the Commissioners of Patents, with his Petition, on the
13th April 1867.
I, CHARLES CROCKFORD, of Holywell, in the County of Flint, Gentleman,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
OBTAINING USEFUL PRODUCTS PROM CERTAIN MATERIALS PRODUCED IN THE PROCESS
OF GALVANISING OR COATING IRON WITH ZINC," to be as follows:-
The first part of my Invention consists in the mode of treating the material
known as bath or flux skimmings, and I proceed as follows:-I boil first the
material in one or two waters and drain the liquor therefrom, and then I grind
it in a wet state and submit the resulting paste-like mass to pressure, whereby
I am enabled practically to obtain the whole of the soluble salts which it
contains; sometimes I omit the boiling as a treatinent preliminary to the
grinding.or I triturate and keep the material agitated in hot water, by which
means I obtain the metallic zinc it contains in a granulated or coarsely
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page_text: divided state; I then proceed to treat the expressed liquor in one of the
following ways:-
1. I precipitate the zinc with milk of lime; taking care to add no more lime
than shall be sufficient for its complete precipitation, and I then distil the
liquor with additional lime and obtain the ammonia therefrom, or after pre-
cipitating the zinc I add an equivalent of sulphate of ammonia, and having
boiled it down to dryness sublime the muriate of ammonia, or by filtration
and pressure separate the sulphate of lime from the muriate of ammonia.
2. I precipitate the zinc with carbonate of soda or sulphide of sodium; the
precipitated carbonate or sulphide of zinc is then submitted to pressure and
the liquor extracted; to this liquor is then added the proper equivalent of
sulphate of ammonia, and the resulting sulphate of soda is extracted by boiling
until its crystals are precipitated, or the whole is boiled down to dryness and
the muriate of ammonia sublimed whilst the sulphate of soda remains in the
subliming pot.
3. I precipitate the zinc with sulphide of barium, and after expressing the
liquer an equivalent of sulphate of ammonia is added, whereby the sulphate
of baryta is precipitated,and the liquor being expressed by pressure from this
precipitate will contain only the muriate of ammonia, which may becrystallised
or otherwise treated.
4. Without precipitating the zinc I add the proper equivalent of sulphate
of ammonia, and afterboiling down todryness sublime the muriate of ammonia
and collect the sulphate of zinc from the subliming pot.
5. I precipitate the oxide of zinc with ammonia, and after expressing the
liquor from the precipitate muriate of ammonia remains in the solution, which
may be crystallised or otherwise treated.
6. I treat the whole of the skimmings or the soluble salts extracted from
them with sulphuric acid in precisely the same manner as salt is treated in
the manufacture of sulphate of soda, the muriatic acid being condensed and
the resulting sulphate of zinc and ammonia left in the decomposing pan may
be separated by sublimation after crystallizing or boiling down to dryness.
The second part of my Invention consists in refining the hard spelter,com-
monly known as dross spelter,collected from the bottom of the baths of zinc,
and produced in the process of galvanizing or coating iron with zinc, and I
proceed as follows:-I charge the hard spelter into the retorts of an ordinary
Belgian furnace, but I only fill the retort about one half from the back eud,
and I fill up the front part of the retort with ground coke or some inert
material, and place the ordinary condensing pipe on a descent or incline, so
that the condensed zinc shall not remain in it but run out directly into a

page_text: proper receiver, whence it may be collected and afterwards be melted and cast
into ingots. By adopting this mode of smelting or refining the hard metal Iam
enabled to obtain a very pure metal and with very little loss from oxidation.
2. In lieu of the ordinary Belgian retort which is cylindrical I make the
retort of an oval or other convenient form, and before charging it with the
zinc I fill it up about one-third with ground coke or some inert material, so
that the iron contained in the hard spelter instead of being deposited on the
bottom of the retort which it destroys may remain on the said inert material,
and be withdrawn therewith without injury to the retort.
The third part of my Invention consists in collecting and condensing the
vapour arising from the galvanizing bath or the bath used or employed in
coating iron with zinc, this I do by condensing the vapours given off from the
bath by means of a hood or cover, and a flue or flues leading into a tower
filled with coke, upon and through amongst which I cause water in a finely-
divided state to fall shower like, so that it percolates through the mass of
coke, and coming into contact with the vapours condenses them; or instead
of using coke in the manner described I connect the flue with any suitable
condenser, and thus condense and collect the vapours.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Charles Crockford in the Great Seal Patent Office on the
12th October 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
CROCKFORD, of Holywell, in the County of Flint, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirteenth day of April, in the year of our Lord
One thousand eight hundred and sixty-seven, in the thirtieth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Charles Crockford, Her special licence that I, the said Charles
Crockford, my executors, administrators, and assigns, or such others as I, the
said Charles Crockford, my executors, administrators, 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 "IM-
PROVEMENTS IN OBTAINING USEFUL PRODUCTS FROM CERTAIN MATERIALS PRODUCED
IN THE PROCESS OF GALVANIZING OR COATING IRON WITH ZINC," upon the condition

page_text: (amongst others) that I, the said Charles Crockford, my executors or admi:
nistrators, by an 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 Charles Crockford, do hereby declare
the nature of iny said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement :-
The first part of my Invention consists in treating the material known as
bath or flux skimmings, and I proceed as follows:-I first boil the material
in one or two waters and drain the liquor therefrom; I then grind it in a wet
state and submit the resulting paste-like mass to pressure, whereby I am
enabled practically to obtain the whole of the soluble salts which it contains;
sometimes I omit the boiling as a treatment preliminary to the grinding; I
then proceed to treat the liquor in one of the following ways:-
1. I precipit.ute the zinc with milk of lime, taking care to add no more
lime than shall be sufficient for its complete precipitation, and after separating
the liquor from the precipitate by pressure I distil it with additional limeaud
obtain ammonia therefrom, or Iadd to it an equivalent of sulphate of ammonia,
whereby the lime is precipitated as sulphate of lime, and after separating the
precipitate from the liquor by pressure the liquor may be boiled down and
crystallized as muriate of ammonia, or otherwise treated.
2. I precipitate the ziue with carbonate of soda or sulphide of sodium, the
liquor being then separated from the precipitate by pressure is treated with an
equivalent of sulphate of ammonia, and by boiling the sulphate of soda is pre-
cipitated, and the muriate of ammonia left in the solution may be crystallized
or otherwise treated, or after adding the sulphate of ammonia the whole may
be boiled down to dryness and the muriate of ammonia separated from the
sulphate of soda by sublimation.
3. I precipitate the zinc with sulphide of barium, and after expressing the
liquor I add to it an equivalent of sulphate of ammonia whereby the sulphate
of baryta is precipitated, and the liquor being separated from the precipitate
by pressure may be boiled down and crystallized as muriate of ammonia, or
the liquorand precipitate maybe boiled downto drynesstogether and separated
afterwards by sublimation.
4. Without precipitating the zinc I add the proper equivalent of sulphate of

page_text: ammonia, and after boiling down to dryness I separate the sulphate of zinc from
the muriate of ammonia by sublimation.
5. I precipitate the oxide of zinc with ammonia, and after separating the
liquor from the precipitate by pressure I boil down and crystallize the
muriate of ammonia.
=
6. I treat the whole of the skimmings or the liquor therefrom with sulphuric
acid in the same manner as salt is treated in the manufacture of sulphate of
soda, the muriatic acid given off being condensed in a suitable condenser; the
resulting sulphates of zinc and ammonia may be separated by sublimation after
crystallizing or boiling down to dryness.
The second part of my Invention consists in the mode of refining the hard
spelter,known as dross spelter, collected from the bottom of the baths of zinc
and produced in the process of galvanizing or coating iron with zinc, and I
proceed as follows:-I charge the hard spelter broken into small pieces into
the retorts of an ordinary Belgian furnace placed with an incline towards the
back end instead of an incline towards the mouth, which is the usual manner.
of placing them, and I only fill the retort to the extent of about one-half its
capacity from the back end, filling up the front of the retort with small coke
or some inert material; 1 theu fix the ordinary conical condensing pipe in the
mouth of the retort, but instead of placing it horizontally I place it on an
incline or descent, so that the condensed zinc shall not remain in it but run
out directly into a receiver, whence it may be collected and afterwards remelted
and cast into ingots. Previous to charging the hard spelter into the retort I
lay on the bottom of the retort a quantity of ground coke or some inert
material, into and among which theironcontained in thehardspelter descends,
and the retort will then be saved from the destructive effects which the iron
has upon it; this iron and coke will be withdrawn from time to time when a
fresh charge of metal is put in; by adopting this mode of smelting or refining
the hard metal I am enabled to obtain a very pure metal with very little loss
by oxidation and with a very little destruction of retorts.
The third part of my Invention consists in collecting and condensing the
vapor arising from the galvanizing bath or the bath used or employed in
coating iron with zinc; this I do by conducting the vapours given off from the
bath by means of a hood or cover and flue or flues into a tower filled with
coke, upon and through amongst which I cause water in a finely divided state
to fall shower like, so that it percolates through the mass of coke, and coming
in contact with the vapours condeuses them in precisely the same manner as
the muriatic acid gas is condensed from the decomposition of common salt by
sulphuric acid. Instead of using a tower and coke in the manner described I

page_text: connect the flue with any suitable condenser, and thus condense and collect
the vapours; the solution of the salts of ammonia and zinc thus obtained may
be treated under any of the processes described in the first part of my
Invention.
وو
Having now particularly described and ascertained the nature of my said
Invention of "Improvements in Obtaining Useful Products from certain
Materials Produced in the Process of Galvanizing or Coating Iron with Zinc,"
and shewn in what manner the same is to be performed and put in practice, I
wish it to be understood that what I claim is as follows:-
First, the mode or method herein described as the first part of my Iuvention
of treating bath or flux skimmings for the purposes set forth.
Second, the after treatment of the expressed liquor byeither of the modes
or methods herein described and set forth.
Third, the mode or method herein described of treating hard spelter and
bath dross.
Fourth, the modes or methods herein described of collecting and condensing
the fumes or vapors given off from galvanizing baths or other vessels or
furnaces during the melting or maintaining in a molten condition spelter or
zinc.
In witness whereof, I, the said Charles Crockford, have hereunto set my
hand and seal, this Eleventh day of October, in the year of our Lord
One thousand eight hundred and sixty-seven.
CHARLES CROCKFORD. (L.S.)