IMPROVEMENTS IN THE MANUFACTURE OF OXIDE OF ZINC, AND IN THE MAKING OF PAINTS AND CEMENTS WHEN OXIDE OF ZINC IS USED
Year: 1849

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
ANDRE FELIX Rocnaz, of New Court, Saint Swithins Lane, in the City of
London, Merchant, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Twenty-eighth day of
February, One thousand eight hundred and forty-nine, in the twelfth year
of Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Charles Andre Felix Rochaz, my exors, adiñors, and assigns,
Her especial licence, full power, sole privilege and authority, that I, the said
Charles Andre Felix Rochaz, my exors, adññiors, and assigns, and such others
as I, the said Charles Andre Felix Rochaz, my exors, admors, or assigns,
should at any time agree with, and no others, from time to time and at all
times during the term of years therein expressed, should and lawfully might
make, use, exercise, and vend, within England, Wales, and the Town of
Berwick-upon-Tweed, my Invention of "IMPROVEMENTS IN THE MANUFACTURE
OF OXIDE OF ZINC, AND IN THE MAKING OF PAINTS AND CEMENTS WHEN
OXIDE OF ZINC IS USED;" in which said Letters Patent is contained a proviso
that I, the said Charles Andre Felix Rochaz, should cause a particular
description of the nature of my said Invention, and in what manner the same
is to be performed, by an instrument in writing under my hand and seal,
to be inrolled in Her said Majesty's High Court of Chancery within six
calendar months next and immediately after the date of the said in part

page_text: recited Letters Patent, as in and by the same, reference being thereunto had,
will more fully and at large appear.
NOW KNOW YE, that in compliance with. the said proviso, I, the said
Charles Andre Felix Rochaz, do hereby declare that the nature of my Inven-
tion, and the manner in which the same is to be performed, are fully described
and ascertained in and by the following statement thereof, reference being had
to the Drawings hereunto annexed, and to the figures and letters marked
thereon, that is to say:-
The principal imperfection of the methods hitherto known for the manu-
facture of oxide of zinc is that they generally give rise to the production of
residues, and of a certain proportion of coarse and imperfect oxide unfit for
paint. It has been also attempted, but without any complete success, to
obtain on a large scale the white and pure oxide of zinc by the direct treat-
ment of zinc ores. The distinctive character of the Invention which is herein
described consists,―
First, of improvements in the furnaces and apparatus employed, by means
of which white oxide of an uniformly perfect quality is obtained from the whole
of the zinc which is introduced into the apparatus, either in a mineral or
metallic state.
Secondly, my Invention consists of obtaining, by the mixture of such white
oxide of zinc with certain substances, a good bodied paint or pigment. And,
Thirdly, my Invention consists of making cements, as hereafter explained,
when using oxide of zinc.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a vertical section of a furnace constructed according to my
Invention, for the conversion of zinc into white oxide. A are crucibles of fire
clay with flat moveable covers having at their centre a round aperture.
B, B, are pillars of fire bricks supporting the crucibles. C, C, moveable slabs
of fire clay, serving as a roof to the furnace, and which can be taken off when
the crucibles are to be cleansed or replaced. D, opening of the fireplace;
E, ash pit; F, part of the furnace whereon the chimney is placed; g, flues
for the gases from the fireplace; d, fire grate; f, iron bars supporting the
grate b; c, cast-iron slab.
Figure 2, vertical section through the line X, Y, of Figure 1. G, longi-
tudinal fue, which receives the products from all the flues marked 9 in
Figure 1. H, space where the combustion of the vapors of zinc takes place,
and which communicates by the opening u with the chamber K, L, where the,
oxide deposits itself. R, door of the chamber. m, sheets of iron or zinc

page_text: fixed across the chamber. n, n, bands of hemp or other textile substance
hanging from the roof of the chamber in transversal rows a short distance
from each other, and at crossed intervals, so that the current after passing
through the spaces of one row meets perpendicularly the bands of the
next row. The lower ends of those bands are fixed on a piece of wood s.
The upper ends of the bands come through the roof or ceiling, where
they are fastened, and their ends enter into a zinc trough t, which
contains water; and in order to be able to shake the bands from time
to time a rope or cord is fixed at each end of the piece of wood, such ropes or
cords being carried up through the ceiling to allow of the workman raising
and lowering the piece of wood so as to shake the bands, by which the bands
will be freed from the oxide which has settled upon them. Three or four
of these systems of rows or curtains of bands will generally be sufficient,
but their number, and that of the rooms or compartments L, with or without
metallic screens, can be multiplied, and the last room or compartment has an
opening or chimney with a register for the regulation of the draft. The
first compartment of the chamber I construct of masonry or sheets of metal
on account of the high temperature created there by the air and oxide on
their issuing from the furnace, but there is great advantage in constructing
the other rooms or compartments entirely of sail cloth or other suitable
fabric, because then any and the most covenient shape and dimensions,
according to the particular premises, can be given to such chambers or
rooms, and especially because it will then be very easy to keep the roof
and sides of this part of the apparatus constantly and abundantly watered,
which is desirable. The oxide adheres more easily to the sides and
bands, it falls quicker, and takes less space, and it can be detached from
the roof and sides by simply beating them externally.
The operation. The crucibles are first filled with metallic zinc and the
covers placed on them, the openings u being stopped with bricks, and the fire
is urged until the metal begins to sublimate, when the bricks are to be
removed from the openings . The vapors issuing from the aperture of the
cover ignite and oxidize by the contact of the air in the spaces H, H, H,
and the currents rushing in carry the products through the opening u, u,
into the chamber K, where they encounter the metallic partitions m, which
compel them to descend and rise before they pass into the part L through
the free space left between the roof and the partition wall, and after
meeting with another metallic screen m, they traverse in succession series
of rows of moistened bands. The oxide settles on the roof, floor, 'sides,
and other parts of the whole of the suite of compartments, and the cur-.

page_text: rent issuing at the chimney should contain a very insignificant portion of
the oxide. The crucibles are to be fed with molten zinc from time to
time. At the beginning of the operation it is well to keep the covers on
the crucibles in order to encrease the heat, but as soon as the whole of the
furnace has become well heated by the flames of the fire underneath and of the
burning zinc, the covers may be removed, the vapors are evolved in greater
quantity, and the operation goes on more rapidly. But during the whole of
the operation, from the moment the zinc flames have begun to appear, concre-
tions form themselves around the borders of the crucibles or the orifice of the
covers. These concretions are formed of oxide which has not been carried away
by the current. That oxide alone which is carried by the current into the
chamber is of good quality; all that which remains is coarse. The workman
should be careful to keep the orifices free from those concretions by moving
the same by a scraper, and he is to remove the same from time to time away
from the furnace. These residues are afterwards treated in the following
manner: They are first mixed with pulverized charcoal or coke, then the
mixture is moistened and moulded into small cakes, or in a form similar to
that of the interior of the crucibles; these are to be placed in the crucibles
and treated as has been done with regard to the metal, with the only difference
that the covers are to remain all the while on the crucibles. The shape of the
crucibles may be varied, and I prefer them to be more shallow when only
treating metal zinc, but when the residues are also to be operated on by the
same crucible, then I prefer to use the shape shown. The process above
described is accelerated and improved by forcing a thin sheet of hot or cold air
on the surface of the melted and burning metal in the crucibles or pans. This
is done by adjusting to the mouths of the furnaces a door, which has at the
lower part an aperture for the passage of the flat tuyere. This blast, by
impinging on and sweeping over the surface of the metal, diminishes materi-
ally the formation of concretions, and increases that of the vapors, while at
the same time a minimum of air being admitted the force of the current in
the chamber is reduced, which saves the loss of oxide at the chimney.
The peculiar character of this part of my Invention consists of obtaining
spaces H over the crucibles or vessels A, as explained; also causing streams
of air to impinge on the melted zinc; also the using of rows of bands; and
also the using of woven fabrics in making the rooms or chambers. The
furnace which I have described could be used in the fabrication of oxide by
the direct process, videlicet, the treatment of zinc ores; but the number of
furnaces required would be great, as the crucibles hold but a limited quantity,
and cannot be placed one over the other. Therefore I prefer to use for the

page_text: treatment of zinc ores two sorts of furnaces, the first of which is fixed on th
disposition of the crucibles in the Belgian method of distillation of zinc, with
the alterations and additions which I now proceed to describe.
FURNACE FOR PRODUCING WHITE ZINC FROM ZINC ORES.
Figure 3 is the front of a furnace, with the crucibles in, and their stoppers
on, adjoining a chamber for the reception of the oxide. A, crucibles or retorts.
B, slabs of fire clay, under thinner slabs of cast iron. G, pillars of fire clay.
separating the crucibles and supporting the slabs. I, section of the stoppers
which are placed during the charging and cleansing of the crucibles to stop
the openings of the passages into the chamber K such as before described.
m2 metallic sheets, as in the former apparatus.
Figure 4 vertical section through the line X, Y, of Figure 3. A crucibles;
B slabs C stoppers, forming with the front of the furnace and the upper
and under slabs, the fourth side of the square spaces for oxidation, which
open into the chamber K by apertures loft in the wall, of the same areal
section as the passages D for oxidation; R, chimney; E, ash pit; d, grate;
f irons bars supporting the. grate. The apparatus consisting of rooms
or compartments for receiving the oxide is to be that above described.
The operation. When the crucibles or retorts have been filled with ore
roasted and mixed with charcoal or coke as usual, the stoppers A', which are
made to fit in the orifice of the crucibles, are put in and luted all round, except
at the upper part where a slope exists for the passage of the vapors. As soon as
the flames issuing from that slope assume the whiteness of zinc flames, the
stoppers I, Figure 3, are to be removed, and the passages D for oxidation are to be
formed by putting in the longitudinal stopper C, Figure 4, and luting them
externally. The currents of air entering at the further ends of the passages D
inflame the vapors, and, carry the oxide into the chamber K. During the
whole of the operation a workman takes care to clear the apertures of the
stoppers A¹ by means of an iron rod crooked at one end. The concretions
fall on the sole of the passages D, and are drawn out from time to time,
and the workman is to push into the chamber K the oxide which deposits
itself in that part of the passages which is formed by the openings into the
chamber K. The cleansing and loading of the crucibles are the same as are
well known to zinc makers as the Belgian method for distilling zinc, and
the operation when properly conducted, and with good ores, can take place
three times in twenty-four hours. The oxide so produced I find to be in
no way inferior to that obtained from the metal in the manner first described,
but as for the first hour after loading the vapors are slow in evolving, and

page_text: mixed with foreign matter during this period, the products of the distillation can
be collected apart in order to preserve the uniformity of the general product.
For this purpose instead of the stoppers A' with slopes, which I have described,
the retorts are each to have one, as represented in Figure 4, having a
prominent ledge, to which is to be adapted a tube similar to those used
in the distillation of zinc. In this case the stoppers C, Figure 4, are only to
be put in one hour after the charging, then the tubes are to be taken off,
and the stoppers I are to be removed. In these tubes the zinc is collected
in a metallic or in a grey oxide state. This mode of treatment is simple,
economical, and possesses not only the advantage of saving almost the whole
of the expense of reducing zinc to its metallic state, but also of collecting
that considerable quantity of oxide which, in the distillation of ores for the
production of blue metal, oozes out and is lost through various parts of
the apparatus. The peculiar character of this apparatus consists in the
arrangement of passages D for oxidizing the zinc vapours, and conducting
them into the chamber K.
Another-anethod, which I will now describe, offers a great saving in fuel and
other expenses.
BLAST FURNACES FOR OBTAINING ZINC WHITE FROM ZINC ORES.
Figure 5 is a vertical section of the furnace. A, A, two passages to receive
the ores mixed with fuel. B, B; are two passages to receive charcoal or coke.
C, covers of the passages. D, flue of oxidation, leading into the chamber K.
The part E will at all times be full of charcoal or coke; the part F is where
the reduction and sublimation takes place, G, cavity into which the slags and
residues descend. H, tuyeres. a, moveable stopper into the oxidizing passage.
The operation. The ores properly roasted and ground are mixed with the
usual proportion of coke or charcoal, and when necessary flux is to be added.
The whole is afterwards moistened and shaped into small bricks or cakes, then
dried. When the fire has been kept up for some time with pure coke, and the
furnace well heated, the mixture of ores and fuel is to be introduced into the
passages A, and the passages B are to be filled with charcoal or coke.
The blast of air, whether hot or cold, is forced in at the tuyeres H, H; the
volatile products find an outlet as soon as the stopper a is removed. The
vapors of zinc burn at that opening, and the oxide is carried through the
passage or flue D into a chamber K, such as above explained. The resi-
dues of the combustion and the lead, if there be any contained in the ores,
are drawn out through an aperture at the lower part of the cavity G. The
peculiar character of this apparatus lies in. the functions of the passages B,

page_text: which form constantly a bed of incandescent coke in the part E, through which
the gases and vapors have to find their way; hence, the vapors which may
have partially become oxidated by the excess of air supplied by the blast aro
again reduced, and reach the opening a in a pure state. And when necessary
I place at the opening a fire-clay partitions or divisions, so arranged as to stop
or intercept the ashes or other particles of foreign matters which may be
mixed with the gases and vapors. I would remark, in respect to this part of
my Invention, that zinc white has before been made, and various furnaces
have been employed for such manufacture, and it has been proposed to use a
blast furnace of an ordinary construction for such purposes. I do not, there-
fore, claim the making oxide of zinc, but only the peculiarities in the
furnaces and annaratne horain decoribed

page_text: They are used with advantage by mixing them with common mortar in the
construction of walls and buildings; the addition of such residues communicates
to the mortar a high degree of hardness.
In witness whereof, I, the said Charles André Felix Rochaz, have here-
unto set my hand and seal, this Twenty-fifth day of August, in the 5
year of our Lord One thousand eight hundred and forty-nine.
C. A. F. (L.s.) ROCHAZ.
AND BE IT REMEMBERED, that on the Twenty-fifth day of August, in
the year of our Lord 1849, the aforesaid Charles Andre Felix Rochaz came
before our said Lady the Queen in Her Chancery, and acknowledged the 1
Specification aforesaid, and all and every thing therein contained and specified,
in form above written. And also the Specification aforesaid was stamped
according to the tenor of the Statute made for that purpose.
Enrolled the Twenty-seventh day of August, in the year of our Lord
One thousand eight hundred and forty-nine.