IMPROVEMENTS IN THE MANU- FACTURE OF SPELTER FROM THE SULPHURET OF ZINC
Year: 1860

page_text: LETTERS PATENT to Charles Crockford; of the Greenfield Spelter Works,
Holywell, Flintshire, for the Invention of "IMPROVEMENTS IN THE MANU-
FACTURE OF SPELTER FROM THE SULPHURET OF ZINC."
Sealed the 23rd April 1861, and dated the 29th October 1860.
PROVISIONAL SPECIFICATION left by the said Charles Crockford at the
Office of the Commissioners of Patents, with his Petition, on the 29th
October 1860.
I, CHARLES CROCKFORD, of the Greenfield Spelter Works, Holywell, Flint-
shire, do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN THE MANUFACTURE OF SPELTER FROM THE SULPHURET OF ZINC," to be as.
follows:-
My Invention consists in modes of utilizing the sulphur contained in the
sulphuret of zinc, and for this purpose I introduce the pulverized sulphuret
O into flat retorts or ovens, heated by fires passing over and under them, or
otherwise, and the mineral is kept continually stirred by means of a series of
rakes travelling backwards and forwards in the said retorts, which rakes are.
supported on a machine very similar to a spinning mule, which is kept in

page_text: motion by machinery, and by this means fresh surfaces of the mineral are
continually exposed to the action of the air, which is admitted at the mouth of
the retorts, and which, being converted into sulphurous acid in its passage
through them, is conducted into a leaden chamber, and there converted into
sulphuric acid in the usual manner; sometimes I prefer heating the air before
admitting it into the retorts, but this is not absolutely necessary.
Another mode which I adopt is to mix the pulverized sulphuret with a
small quantity of clay or other plastic material, and mould it into small bricks
or balls, which, after being dried, are burnt in kilos or ovens connected with a
leaden chamber, the said kilns being heated externally by fire; or I burn with
the said balls or bricks a certain proportion of pyrites, the combustion of
which generates sufficient heat for the desulphurizing of the sulphuret of zinc,
without the necessity of beating the kilns externally.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Charles Crockford in the Great Seal Patent Office on the
27th April 1861.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
CROCKFORD, of the Greenfield Spelter Works, Holywell, Flintshire, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-ninth day of October, in the year of our
Lord One thousand eight hundred and sixty, in the twenty-fourth 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 exccutors, 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 "IMPROVEMENTS IN
THE MANUFACTURE OF SPELTER FROM THE SULPHURET OF ZINC," upon the con-
dition (amongst others) that I, the said Charles Crockford, my executors or
administrators, 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

page_text: the same to be filed in the Great Seal Patent Office within six calender
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 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:
The object of my present Invention being the desulphurizing of the sul-
phuret of zinc, to enable it to be readily and economically manufactured into
the spelter of commerce, and whilst so treating the said or such like materials,
collecting and utilizing the sulphur, which, in the ordinary process of manu-
facturing spelter is dissipated or wasted.
The modes or methods which I prefer to employ in carrying my present
Invention into practice are as herein-after described; but whichever process
of after treatment be adopted, I proceed to prepare the sulphuret of zinc, in
accordance with my present Invention, by pulverizing it, and either use it in
the form of powder, or mould it into balls, nodules, or other suitable forms,
and in one case submitting it to the action of heat on a hearth, or in a com-
partment to which heat is externally applied, or in the other case burning it in
a kiln; the said hearth or the kiln is to be connected with a leaden chamber,
in which the sulphurous vapours are collected, and by the ordinary means
converted into sulphuric acid.
Having pulverised the said ores of zinc by any of the well known means, I
expose it to the action of heat on a hearth, or in a compartment or chamber,
where the products of combustion from the fuel are kept seperate from the
material in course of treatment.
The hearth, compartment, or chamber which I prefer to employ for this
purpose is constructed in the following manner :-I build a series of compart-
ments of fire-brick, fire-tile, or fire-lumps, on a floor of similar material, and
by forming the flues above and below such compartments or chambers I carry
or conduct the heat first above and then below the said compartments, and, by
this means connection is made between the grate or furnace in which the fuel
is burnt and the chimney in which the up draught exists, and by which com-
bustion is maintained.
The powdered sulphuret of zinc lying upon the hearth in a quiescent
condition would not yield up or give off the whole of the sulphur contained
therein, as the pulverised condition of the material, when so employed, requires
that the heat and atmospheric air should have free access to or come in contact-
with the finely divided particles or pieces of sulphuret. For this purpose, and

page_text: to enable the whole of the material lying upon the hearth to be properly acted
upon,
I have contrived an arrangement of mechanical rakes by which, either
with one or more rakes to each hearth or chamber, the material, whilst being
subject to the action of heat upon a hearth, or several hearths, or in several
compartments, is constantly moved, disturbed, or kept in motion; and, by the
aid of an attendant, one or several machines, containing a number of rakes,
may be self-actingly employed.
The machine for raking consists of a frame or carriage which is mounted on
wheels running over a tramway or lines of rails. Upon this frame or carriage
is mounted a series of rakes fixed horizontally and projecting in advance of
the frame to an extent, at least, equal to the length of the compartments or
hearth wherein or whereon they are intended to work; and, by a motion
given to the frame in the direction alternately back and forth, the rakes are
caused to traverse the floor and so keep the finely divided mineral in motion;
exposing a fresh surface continually to the action of the air.
The sulphurous vapour driven off from the contents of the floor or hearth
is conducted by means of pipes or passages into a leaden chamber, where it is
converted into sulphuric acid in the usual manner. The machine containing
the rakes is caused to travel back and forth in a manner similar to the motion
of the mule in thread-spinning, and the depth of each rake being proportioned
to the depth of the pulverised material intended to be placed upon the floor of
each compartment or hearth, the material accumulates in the form of a mound
in advance of the rake in whichever direction it is travelling, and then falls
over behind the rake to about the same depth as before; and when the rake
has reached nearly the end of its travel, it is caused to rise over the material
in advance of it, and when it is quite clear it descends, and the direction of its
motion is changed, and it is made to return bringing with it the material as
before, but in a contrary direction, and thus the whole of the material upon
each hearth is moved, and the accumulation which would otherwise take place
at the end of each stroke is prevented, the material being again disturbed and
fresh particles become exposed to the action of the air which is permitted to
enter each compartment under regulation, and the sulphurous vapour or gas
thus liberated is made to pass into the condensing chamber, and is converted
into sulphuric acid, as before described.
The novel feature in the arrangement of flues, and the application of heat
to the treatment of sulphuret of zinc, as herein described, is, that the heat is
first carried over and then under the floor of the compartments or hearth upon
which the material is kept in motion, by which means the greatest heat is

page_text: obtained on the surface of the material, and the floor is thereby protected from
"slagging" or becoming destroyed.
For the purpose of preparing the pulverised material to be treated or
subjected to the action of heat in a kiln or close furnace, with or without the
direct aid of fuel, I proceed as follows:-Instead of placing the pulverised
sulphuret of zinc ore upon the hearth or floor of the compartment, as before
described, I intimately mix with it clay or some other suitable plastic material,
by which the particles are kept apart or separated; and I then mould them
into form, as before mentioned, by hand, or otherwise; and after they have
been dried I place them in a kiln, and burn them in the ordinary way; the
kiln being connected with a leaden chamber, the sulphur is there collected;
condensed, and converted into sulphuric acid. Instead of mixing the pulverised
sulphuret of zinc ore with clay, and drying, and afterwards burning it, as just
described, I prefer, in some cases, and where the fineness of the reduction and
the nature of the ore permits, to take the finely divided or powdered material
alone, and form it into balls, or other suitable forms, and proceed to kiln
them. In other cases I take the material after it has been pulverised, mixed
and moulded, and I burn the moulded masses with a sufficient proportion of
pyrites, the combustion of which generates sufficient heat for the desulphurising
of the sulphuret of zinc, with or without external heat applied to the kilns.
For desulphurizing some descriptions of sulphuret of zinc I apply additional
heat externally to the kilns wherein the balls or nodules are to be burnt.
Having now described my said Invention of "Improvements in the Manu-
facture of Spelter from the Sulphuret of Zinc," I claim,―
First, the construction of the compartments or hearths, as herein described,
with flues for the purpose of applying heat to the pulverised sulphuret of zinc,
as herein set forth.
Second, the construction of and mode or method of working the machinery
or apparatus, as herein described, for the purpose of acting upon, raking, or
keeping in motion pulverised sulphuret of zinc, as described.
Third, making up into balls or nodules, and treating sulphuret of zinc in
manner described, for the purpose of enabling the material more readily to
part with its sulphur, whereby such sulphur may be utilised, as herein
set forth.
Fourth, the application of external beat to kilns wherein balls or nodules
(formed as described) are burning, for the purpose of facilitating their
desulphurization.
Fifth, treating the sulphuret of zinc in one or other of the modes or

page_text: methods herein-before described, for the purpose of utilising the sulphur
contained therein.
In witness whereof, I, the said Charles Crockford, have hereunto set my
hand and seal, this Twenty-sixth day of April, One thousand eight
hundred and sixty-one.
Witness,
EDWARD JAMES WHITEHOUSE,
Clerk, Holywell.
CHARLES CROCKFORD. (L.S.)