IMPROVEMENTS IN THE MANUFACTURE OF ZINC WHITE
Year: 1864

page_text: LETTERS PATENT to George Darlington, of Minera, in the County of
Denbigh, Zinc Smelter, for the Invention of "IMPROVEMENTS IN THE
MANUFACTURE OF ZINC WHITE."
Sealed the 31st March 1864, and dated the 26th January 1864.
PROVISIONAL SPECIFICATION left by the said George Darlington at
the Office of the Commissioners of Patents, with his Petition, on the
26th January 1864.
I, GEORGE DARLINGTON, of Minera, in the County of Denbigh, Zinc
Smelter, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN THE MANUFACTURE OF ZINC WHITE," to be as follows:-
My improvements consist in the production of zinc white (white oxide of
zine) from oxidised compounds of zinc, such as roasted blende, calcined
calamines, zinc ashes, zine dross, or old zinc, by mixing such materials
with coal or coke from which all their original gaseous matters have been
expelled by heat or any other well known means, the proportion of such
admixture being usually about 3 parts of fuel to one part of metal con-
tained in the ore, but such proportion being necessarily dependant upon the
fusibility of the gangue of the ore, the proportion of fuel to be increased or
decreased as the ore is difficult or easy of fusion, and I place such a mixture
in a blast furnace, in which the said mixture or charge is kept in a state of
combustion by the passage through it of numerous jets of air entering the
said furnace through blast orifices, such air being supplied by a blast engine
either in a hot or cold state, and I further complete the oxidation of the zinc
fumes, which will be produced by this means by the admission of fresh air either

page_text: heated or cold into the said furnace immediately above the surface of its con-
tained charge, such air being forced into the said furnace through numerous
apertures by a blast machine, and in order to render the process more perfect
I exhaust the gaseous and volatile contents of the said furnace containing the
oxide of zinc which will be produced by this arrangement by means of an
exhaust engine, either cylinder, fan, or other similar machine, which shall
effect exhaustion.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said George Darlington in the Great Seal Patent Office on the
5th April 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
DARLINGTON, of Minera, in the County of Denbeigh, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-sixth day of January, in the year of our Lord
One thousand eight hundred and sixty-four, in the twenty-seventh year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said George Darlington, Her special licence that I, the said George
Darlington, my executors, administrators, and assigns, or such others as
I, the said George Darlington, 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 "IMPROVEMENTS IN THE MANUFACTURE OF ZINC WHITE," upon the condition
(amongst others) that I, the said George Darlington, my executors or ad-
ministrators, 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 per-
formed, 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 George Darlington, 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:-
My improvements consist in the production of white oxide of zinc from

page_text: "
oxidised compounds of zinc, such as roasted zinc blende, calcined calamines,
zinc ashes, and zinc dross, by mixing such compounds with coal or coke from
which all gaseous matters have been expelled, and placing such mixture in a
blast furnace, in which the bottom and sides below the level of the contained
charge" are perforated with numerous holes or apertures for the admission
of air, which is supplied either hot or cold by an air blowing machine, and
further I complete the oxidation of the zinc fumes which will be so produced
by means of the admission of hot or cold atmospheric air passed into the
furnace above the level of the charge in the furnace through an aperture or
several apertures in the side or sides of the said furnace. And in order to
render the whole of the operations more complete, I exhaust the entire
gaseous products of the furnace, which products will contain the oxide of zinc
mechanically suspended in them by means of a suction fan or cylinder or other
exhaust machine or apparatus.
In order to give a more complete description of the above outline of my
process for the production of a pure white oxide of zinc, I will now describe
the exact form of the process as carried on by me at the present time. Upon
the bottom of the furnace (which is somewhat similar in form to the old coke
oven), and through which several hundreds of small blast pipes pass, I place
a mass of fuel and gently turn on the blast; as soon as this fuel is thoroughly
incandescent, I add the charge of ore and fuel which are already intimately
mixed and the ore ground to the size of peas and well dried, while the fuel
has not only been heated in the same manner but has been thoroughly ignited
to drive off all volatile inatters, and kept in that condition of red heat for an
hour, this part of the process having been effected in a separate furnace.
This mixture should have a proportion of about, on an average, one pound
or part of fuel to one pound or part of metallic zinc in the ore, but if the ore
should have a very refractory gangue, such as sulphate of baryta, carbonate of
iron, silica, or alumina, it may be necessary to increase this quantity of fuel, or
if the ore be very soft and fusible to diminish it. The charge in a furnace
of a sectional area of about 27 feet (the best size, I believe), should be about
5 cwts., and is projected or thrown into the furnace through a door which may
be opened and shut in its front; shortly after the introduction of the charge
the blast which has been slowly allowed to play through the contents of the
furnace while charging will now be allowed full play, and for a while the
gaseous products of the furnace allowed to escape into the open air through
When these gases
an aperture in the top of the furnace left for this purpose.
become green in colour this aperture is closed and the exhaust apparatus is put
into action, at the same moment the oxidising air is allowed to enter the

page_text: furnace, this air enters the furnace say 6" (six inches) above the level of the
charge in it, and enters through numerous small blast pipes perforating the
furnace; by this means the metallic zinc produced in the first instance by
the action of hot carbon on the oxide of zinc contained in the ore is perfectly
oxidised, and all carbon or carbo-hydrogen compounds from the fuel are con-
sumed and converted into carbonic acid and water and a perfectly white oxide
of zinc produced, which last, mechanically mingled with the furnace gases, is
conveyed into the collecting apparatus by the suction or exhaust arrangement
before mentioned.
Having thus described my said Invention, and the manner in which the
same is to be performed, I declare that I claim,-
First, the oxidation of the products of the combustion of the contents of the
furnace, (that is to say, the fuel and ore,) by the introduction of a hot or cold
blast of air into the said products at a short distance above the level of the
charge from which they are generated.
And secondly, the abstraction or exhaustion of such gaseous contents of the
furnace which contain the oxide of zinc mechanically suspended in them, and
the forcing of them by mechanical means, such as fans, cylinders, or other
similar contrivances, into the collecting apparatus.
In witness whereof, I, the said George Darlington, have hereunto
set my hand and seal, this Fourth day of April, in the year of our
Lord One thousand eight hundred and sixty-four.
Witness,
THO. BLACKBURN,
Liverpool.
GEO. DARLINGTON. (L.s.)