IMPROVEMENTS IN THE MANU- FACTURE OF LEAD PIGMENT
Year: 1879

page_text: LETTERS PATENT to Herbert John Haddan, of the Firm of Herbert and
Company, Solicitors of Patents, of 67, Strand, in the City of Westminster,
Civil Engineer, for the Invention of " IMPROVEMENTS IN THE MANU-
FACTURE OF LEAD PIGMENT." A communication from abroad by Adolph
Faber du Faur, of Newark, New Jersey, and Franz Fohr, of New York, both
in the United States of America.
PROVISIONAL SPECIFICATION left by the said Herbert John Haddan at
the Office of the Commissioners of Patents on the 12th August 1879.
HERBERT JOHN HADDAN, of the Firm of Herbert and Company, Solicitors of
Patents, of 67, Strand, in the City of Westminster, Civil Engineer. "IMPROVEMENTS
IN THE MANUFACTURE OF LEAD PIGMENT.” A communication from abroad by
Adolph Faber du Faur, of Newark, New Jersey, and Franz Fohr, of New York,
both in the United States of America.
The Invention consists in producing lead pigment from galena or other compounds
of lead and sulphur by subjecting the heated material to a blast of air, by preference
hot air, without bringing the galena in contact with the fuel, flame, or reducing
gases, and collecting the product in the usual manner in flues, chambers, and bags.
The process may be carried out by means of a hearth covered with an arch over
which pass the hot gases or products of combustion from a furnace or furnaces,
before they escape to the chimney, heating on their way the blast which is to be
discharged into the hearth. It is preferred to fill first the pan or hearth with
metalic lead to a suitable depth and to introduce the galena through a hopper,
together with any suitable fluxes, such as limestone, litharge. The materials thus
charged are then heated from the top and advance towards the blast of hot air, by
which they are oxidised and partly vaporised. The fumes and hot gases leave the .
hearth through a flue which carries them to an ordinary separating chamber.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Herbert John Haddan in the Great Seal Patent Office on
the 9th February 1880.
HERBERT JOHN HADDAN, of the Firm of Herbert and Company, Solicitors of
Patents, of 67, Strand, in the City of Westminster, Civil Engineer. "IMPROVEMENTS
IN THE MANUFACTURE OF LEAD PIGMENT." A communication from abroadby
Adolph Faber du Faur, of Newark, New Jersey, and Franz Fobr, of New York,
both in the United States of America.
:
Lead pigments have been made by mixing roasted or unroasted pulverized-galena
with carbon, heating the mixture in a compound reducing and oxidizing furnace, and
collecting the fumes in chambers and bags. Lead pigment is also alleged to have
been made by feeding pulverized silver lead ores into the flame of a furnace by
means of an air blast, and submitting the ore to the direct action of a flame.
The presence of carbon, flame, or reducing gases in the process just referred to,
causes the reduction of an unnecessarily large quantity of lead and also injures the
quality of the product by an admixture of small particles of carbon or smoke from
the fuel.
The herein described process consists in the manufacture of lead pigment from
galena or other compounds of lead and sulphur, by subjecting the heated materials
to a blast of atmospheric air, by preference heated air, without mixing the galena
with fuel, and without bringing the galena or the fumes from the same in contact
with fuel, flame, or reducing gases, the products being collected in the usual manner
in flues, chambers, and bags.
When galena is heated at the exclusion of reducing agents, as for instance by placing
a scorifier containing galena into a heated muffle, the galena melts at a bright red
beat, without giving off considerable quantities of fumes, but the moment a blast
of air is turned against the heated mass, dense volumes of white fumes rise from
the same and are carried off by the current. The same résult is also produced by
introducing the blast beneath the surface of the heated material. The fumes are
heavy and of good color, their density being increased by not being diluted by the
products of combustion of the fuel, as in the old process, while the absence of carbon
or flame insures a better color.
I
In carrying out this process a furnace is used by preference as shown in the..
accompanying drawing in which Fig. 1 is a horizontal section at z, z, Fig. 2; Fig. 2
is a vertical section at x, x, Fig. 1; Fig. 3 is a vertical section at y, y, Fig. 1.
Similar letters indicate corresponding parts. The letter A designates the hearth
on which the galena is burned. It is formed of an iron pan a with a lining 6 of
fire bricks or other suitable material, or an iron pan without lining may be used,
e and e' are castings on the sides of the hearth cooled by water pipes in the usual
manner, h is a water cooled casting in front. C is a thin arch above the hearth
which arch is heated by flame passing through the space E between the arch Cand
the upper arch D. B and B are fireplaces of the usual construction and commu-
nication with the space E.
From the space E the flame passes through the flue f to the chamber F, which in
an upward direction communicates with the hot blast chamber G, while one end
communicates with the chimney M. Above the hot blast chamber G with the hot
blast apparatus g is the flue H, which also leads to the chimney. By dampers
placed between the flues F and H and the chimney the heat passing into the hot
blast oven can be regulated. The flame from the fire place does not enter the
hearth A. t, t, t², to, are blast nozzles discharging the hot blast into the hearth;
waters' tuyeres may be used in connection with the same. N is a hopper for
charging the galena, m, m, are openings for giving access to the hearth, c-d represents
an automatic tap by which the lead bath on the hearth is kept at a nearly constant
level. On both sides of the automatic tap are cylinder taps o. I is a round flue

page_text: through which the fumes and hot gases leave the hearth and are by the pipe K
carried to the separating chambers, suction fan, and bags, in the manner generally
practised for collecting oxide of zinc. L is an adjustable sliding piece or sleeve, by
which the admission of external air into the pipe is regulated.
The pan is filled with metallic lead to a depth of about 7 or 8 inches. The galena
which must be as free as possible from foreign substances, is charged through the
hopper N and opening O, and floats on the top of the lead bath. Matte, litharge,
lime stone, or other suitable fluxes may be charged with the galena. The materials
charged into the furnace are heated by the arch above and gradually advance
towards the blast of hot air, by which they are oxidized and to a great extent
vaporized. When very hot blast is used, the heated arch may be dispensed with,
and the air may also be blown into the mass beneath its surface. In this case the
operation must be started with melted galena, or by putting the first charge on the
top of fuel. The hearth must in this case also be of greater depth and of smaller
diameter or surface. Even by this process the formation of metallic lead is not
necessarily avoided, although much less is reduced than by the old processes, and
any excess collecting in the pan may be laddled out or drawn off through the
automatic tan.