An Improved Process and Apparatus for the Manufacture of White Lead and other Lead Pigments.
Year: 1892

page_text: An Improved Process and Apparatus for the Manufacture of White
Lead and other Lead Pigments.
1
:
I GEORGE DENSMORE COLEMAN of No. 2631 Stewart Avenue in the City of
Chicago, County of Cook and State of Illinois, United States of America, White
Lead Manufacturer do hereby declare the nature of this invention and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement :-
The present invention relates to the treatment of metallic lead in a divided or
comminuted state, so as to corrode the same and produce at will either of the follow-
ing lead products or compounds, viz.: lead-suboxide, lead-protoxide, or lead-hydro-
carbonate, commonly called white lead, or mixtures of either of the same.
.!
The present invention has as its basis, the recognition, and application of the
primary and fundamental fact that the chemical reactions in the interior of the
apparatus are greatly dependant upon, as well as sensitive and responsive to, even
comparatively moderate physical changes of pressure and temperature; by the
proper regulation and control of such physical agencies, I am enabled in my present
process to hasten, or retard chemical action to such a degree, that lead-suboxide,
lead-protoxide, or lead-hydrocarbonate can be produced at will, as distinct and
separate articles of manufacture.
A want of recognition, and an absence of control and regulation, of such physical
agencies in what may be termed the tumbling process of producing white lead, have
heretofore rendered all such prior attempts, to manufacture white lead unsuccessful,
based as they were upon the misconception that chemical forces alone needed
attention and were to be depended upon alone to bring the growth and development
of this tumbling process to a practical success.
My present improvement, therefore embraces:
First, a process of treating comminuted metallic lead, in which the temperature
and pressure is under complete control and regulation, so as to enable the production
at will of either, lead-suboxide, lead-protoxide, or lead-hydrocarbonate, or white
lead, but preferably the lead-suboxide, for the reasons hereinafter set forth.
Second, an improved apparatus for carrying out said process, involving the
following features:
An improved construction and arrangement of the parts of a lead corroding
apparatus, whereby a convenient and perfect control is afforded, of the water supply
or flow, by which the rise in temperature due to chemical, as well as frictional or
mechanical action, within the corroding cylinder is regulated, and the particles of
metallic lead kept clean and bright, by the removal of corroded product as fast as
formed; as well as the positive induction and eduction of the gases employed in the
corroding operation; an automatic feeding attachment for replenishing the supply
of comminuted lead, within the corroding cylinder, to compensate for the amount

page_text: carried away, in the form of a corroded product, in the continued operation of the
apparatus; and an improved construction of the inner periphery of the revolving
corroding cylinder, or drum, whereby the frictional wear due to the rolling or
shifting movement of the lead particles within the same, is confined to the top surface
of the series of longitudinal ribs on the inner periphery of the corroding cylinder
or drum.
In the accompanying drawings illustrating my improved apparatus :
Figure 1, is a longitudinal sectional elevation of the corroding apparatus ;
Figure 2, a transverse sectional elevation at line -, Figure 1;
Figure 3, a detached sectional elevation of the mechanism for imparting motion
to the automatic feeding device for the comminuted lead;
Figure 4, an enlarged detail section of the automatic feeding device proper ;
Figure 5, an enlarged detail transverse section of the gas and water pipes within
the cylinder;
Figure 6, a detail section of a part of the wall of the cylinder showing the relative
arrangement of the longitudinal ribs on the inner periphery of the same.
Similar numerals of reference indicate like parts in the different views.
Referring to the drawings, 1, represents the horizontally arranged corroding
cylinder or drum, of wood or metal as desired, and provided with axial trunnions by
which it is journalled to rotate in the end standards 2 of a suitable frame 3; con-
tinuous rotary motion being imparted to the cylinder in any suitable and well known
manner, preferably by a countershaft 4, supported in bearings in the standards 2,
pinions 6, and gears 7 and 8.
9, is a man-hole at one or both ends of the cylinder for access to the interior of
the same, and through which the supply of comminuted lead, can be introduced in
the initial starting of the apparatus, the subsequent supply being effected auto-
matically and continuously by automatic feeding mechanism hereinafter more fully
described.
The inner periphery of the cylinder or drum 1, will be lined with any suitable
uncorrodable material, preferably sheet brass, and provided with a series of longi-
tudinal ribs or bars 10, having an oblong square formation and arranged in close
relation to each other, as illustrated in Figure 6, so as to leave a space or cavity
between adjacent ribs, of a width about equal to the width of the top face of a rib
or bar 10. This arrangement provides narrow longitudinal cavities around the
inner periphery, that fill with a body of the lead particles at their lower positions,
and hold the same to form a frictional surface, even with the top of the ribs ; in
this manner, wear upon the ribs is restricted to the top surface of the ribs alone, and
in consequence the lifetime of the ribs is extended to a great length.
The trunnions of the corroding cylinder are made hollow for the passage of the
axial pipes, by which the flow of water and gases, takes place through the corroding
chamber, leakage being prevented at each cylinder head, around said pipes, by
means of the stuffing boxes or glands 11.
Said pipes as illustrated in the drawings, consists of the induction and eduction,
non-rotary sections of water pipes 12 14 and 13, and the similar induction and
eduction non-rotary sections of gas or air pipe 14 12 and 15, that are arranged to
surround the water pipe sections, as shown. The induction pipe sections 12 and 14,
being, respectively, perforated and slotted along their length within the interior of
the corroding cylinder, so as to evenly distribute the water and gas along the whole
length of such cylinder; while the eduction sections of pipe 13 and 15, communicate
with the interior of the corroding cylinder in the following manner: the air
eduction pipe 15, by means of a lateral opening 16, and the water eduction pipe by
means of an open ended downwardly extending branch 17, that dips into the
contained water in the corroding cylinder; said branch pipe being preferably
arranged, in an oblique direction so as to take water at a point removed from the
end of the corroding cylinder.
The different pipe sections 12, 13, 14, 15, and 17, are connected together, so as to
brace and support each other by means of a hollow Y-shaped plug 18, which affords

page_text: a very convenient support for the inner ends of the different pipe sections, as clearly
indicated in Figure 1.
The passage of the water air induction and water eduction pipes 12, and 13,
through the ends of the respective air outer induction and eduction pipes 14 and 15,
is effected in a tight manner by means of glands or stuffing boxes 19 and 20, in the
respective couplings of the pipe sections 12 14 and 13 15, with their The air inlet
branch pipe 25 and outlet branch pipes 21 and 22, through which the air or other
gas is introduced under pressure from a suitable accumulator or other source, and
discharged into a succeeding corroding chamber, or other escape as desired, such
escape being controlled and regulated by a valve 23, in the outlet branch pipe.
The water eduction or outlet branch pipe 22 is similarly provided with a valve 24,
so as to regulate the flow of water through the corroding cylinder, and in consequence,
the degree of temperature therein, caused by mechanical as well as chemical action;
the water inlet or induction branch 25 21, being connected to a pump, or other
suitable source of water pressure supply.
Suitable gauges, not shown, may be employed to indicate the temperature, as well
as the pressure prevailing within the corroding cylinder.
The gaseous body employed in the corroding cylinder will usually consist of
atmospheric air, as affording in a very cheap and convenient form, the necessary
oxygen required in the formation of the lead-suboxide or protoxide, when however,
a lead-hydrocarbonate alone, or a mixture thereof with the sub or protoxide is
required, the gaseous supply to the corroding cylinder will consist of a mixture of
atmospheric air and carbonic acid gas.
An automatic feeding mechanism as follows, is provided for introducing a constant
and limited supply of comminuted metallic lead, to compensate for the amount
abstracted in the form of corroded lead:
In this, 26 is a rotary cylinder receiving an intermittent rotary inotion from the
driving countershaft 4, of the apparatus, or other suitable source of motion, through
the eccentric 27 on said shaft, eccentric rod 28, rock arm 29, carrying a pawl 30,
that engages and actuates a ratchet wheel 31, fixed on the hub of the cylinder 25, 26,
to effect the desired intermittent rotation of the same. The rock arm 29, has a
pivotal movement on the hub of the cylinder 26, and the connection of the eccentric
rod 28 thereto, is adjustable in a radial direction to or from the axis of the
cylinder 26, so as to regulate the speed with which the same is rotated.
The periphery of the cylinder 26, is formed with a number of pockets or
recesses 32, that take a supply of comminuted lead from the upper chamber of the
casing 33 of such cylinder, to carry it to the lower chamber thereof.
In the construction shown the upper chamber is in connection with the supply
funnel or hopper 34; while the lower chamber is in communication with the air
water inlet or induction pipe section 14, into which the lead drops, to be conveyed
by the spiral conveyor 35, forward into the corroding cylinder.
The spiral conveyor 35 is on a sleeve surrounding the water air induction pipe 12,
and passes out through the gland or stuffing box 19, and is provided with a belt
pulley 36, by which motion is imparted to the spiral conveyor from any suitable
source.
37, is a gland or stuffing box formation for preventing a leakage at the joint,
between the conveyor sleeve, and the water air induction pipe.
38, is a straight-way valve immediately beneath the feeding cylinder 26, for the
purpose of closing the communication between the same and the interior of the
corroding cylinder, when it is desired to repair such mechanism, or for and other
required uses.
In carrying my improved process into effect the following general directions may
be observed:
Charge the corroding cylinder (usually of a size, 4 feet in diameter and 5 feet
long) with a proper quantity of granulated lead, say five hundred pounds and sufficient
water to reach an indicated water level, below the axis of the cylinder, and air,
either alone or combined with carbonic acid gas in about equal volumes; to fill the

page_text: space above the water. Then impart rotary movement to the cylinder, usually
40 to 65 revolutions per minute, until the resultant product is of a bluish tint.
Preserve a continuous in and out flowing stream of water through the cylinder in
order to attain the following results:
The control and regulation of the temperature in the cylinder by increasing
or decreasing the volume, temperature, or flow of the water; and the washing
out and removal of the products of corrosion from the cylinder, so as to keep
the lead bright and clean, and in the best possible condition for oxidation, attrition
and carbonation, in a continuous manner and at the same time afford a continuous
sample of the product for inspection, at the point of discharge from the water
eduction pipe; the gas supply, under pressure, being maintained intact by any
usual means.
In the present process the temperature within the cylinder is derived from the chemical
and mechanical reactions taking place within the same, and the volume of heat generated
during the process is very large, for example, with a cylinder charged as above described,
with five hundred pounds of granulated metallic lead, sufficient water, at an initial
temperature, of 65° Fahr. with forty recolutions per minute, and no water flow to carry
off any of the heat generated, it has been found that the temperature within the cylinder
will rise to as high as 150° Fahr. in the course of three hours operation of the
cylinder.
Such temperature within the apparatus is regulated by the quantity of water flowing
through the same, to absorb and carry off the excess of heat, and such flow of water is
regulated to preserve the proper temperature required within the cylinder by the valve 24,
in the water outflow pipe 22.
The pressure within the apparatus is controlled by the valve 23 in the air outlet pipe,
which can be fully closed to maintain the maximum pressure from an accumulator or
other suitable source of gaseous supply under pressure; and by regulating the amount of
opening of said valve 23, any desired pressure may be maintained within the cylinder,
down to the ordinary atmospheric
From practical experiment
pressure.
find the following degrees of temperature, and
pressure, best adapted to the rapid formation of the different desired products of
the present corroding process, to-wit: lead-suboxide, lead-protoxide, and lead-
hydrocarbonate, or a mixture of the same.
Formula 1. For the production of lead-suboxide, a temperature of 150° to
210° Fahr., and under the ordinary atmospheric pressure.
Formula 2. For the production of lead-hydrocarbonate or white lead, a
temperature of 75° to 150° Fahr., and a pressure of 30 lbs.
Formula 3. For the production of lead-protoxide, a temperature of 75° to
150° Fahr., and a pressure of 15 lbs.
Formula 4. For the production of a mixture of lead-suboxide, lead-protoxide,
and lead-hydrocarbonate, a temperature of 32 to 75 Fahr., and a pressure of
15.lbs.
If the purpose is to produce lead-suboxide, Formula 1, will be followed, until
the charge is oxidized and converted into substantially pure lead-suboxide as
indicated by its blue-black color. In following this formula the presence of air
alone is required, and the supply of carbonic acid gas will in consequence be
cut off.
White lead can be made directly, by following Formula No. 2, and rotating
the corroding cylinder according to the general instructions therefor, until its
contents are oxidized and carbonated, and have a blue tint and consist of white
lead colored by a little lead-suboxide; which can be subsequently treated in any
suitable manner with air and carbonic acid to be converted to a uniform standard
of color, &c.
'
Lead-protoxide can be made by following. Formula No. 3, and rotating the
cylinder according to the general directions or until its contents are oxidized and
consist of substantially pure lead-protoxide as indicated by the yellow color and
the proper tests..

page_text: White lead can also be made by following Formula No. 4, and rotating the
cylinder and otherwise proceeding as in Formula 2.
Formula No. 1, is best for making lead-suboxide, the high temperature causing
rapid oxidation and at the same time a strictly pure lead-suboxide is formed, under
new physical and chemical conditions, that give it an unequalled facility of
oxidation and carbonation.
The effect and importance of pressure in raising the decomposing temperature
of white lead is shown in Formulas 1 and 2, where it is raised from 75° Fahr.
in Formula 1, to 150° Fahr. in Formula 2, by increasing the pressure from 15 lbs.
in Formula 1, to 30 lbs. in Formula 2. By such means it becomes practicable
to use those temperatures and pressures that are the most simple and effective in
operation and at the same time the most rapid and desirable in the products, and
other results obtained therefrom. In fact it thus becomes a possible and simple
matter to calculate in advance a pressure and temperature combination or formula,
suited to the use of any particular pressure or temperature that may be desired.
for any special use or purpose.
In view therefore of the great number of such rules or combinations that would
have a practical and important application for the purposes herein specified, I do
not confine my present invention to any one precise or particular formula, hereto-
fore given, and may modify and change the same as particular circumstances, and
the judgement of the operator may suggest without departing from the spirit of
my present invention.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed I declare that what I claim is
1. The herein described improvement in the art of corroding lead, in the
presence of water and a suitable corroding gas, the same consisting in preserving
the surface of the lead particles in a clean condition, best adapted for corrosive
action, by a flow of water that acts to remove the corroded lead as fast as formed,
substantially as herein described.
2. The herein described improvement in the art of corroding lead, in the
presence of water and a suitable corroding gas, the same consisting in conducting
the corroding process under definite and controllable degrees of pressure and
temperature, and at the same time preserving the surfaces of the lead particles
in a clean condition, best adapted for corrosive action, by a flow of water, that.
acts to remove the corroded lead as fast as formed, as well as to carry off the
surplus heat generated by the physical and chemical reactions in the process,
substantially as herein described.
3. The herein described improvement in the art of making lead-protoxide, which
consists, firstly, in subjecting a body of comminuted lead in a state of agitation
within a suitable vessel, to the action of atmospheric air and water; secondly,.
removing the oxide as fast as formed, and controlling the temperature during the
process by a regulated in and out flow of water through the corroding vessel and
its contents; and thirdly, replacing the lead removed during the process in the
form of oxide, by a regulated supply of comminuted lead; the supplies of air,
water and comminuted lead being regulated with regard to each other.
4. The herein described improvement in the art of making lead-protoxide, which
consists, firstly, in subjecting a body of comminuted lead in a state of agitation
and at a temperature between 75° and 150° Fahr. within a suitable vessel, to the
action of atmospheric air and water; secondly, removing the oxide as fast as
formed, and controlling the temperature during the process by a regulated in and
out flow of water through the corroding vessel and its contents; and thirdly,"
replacing the lead removed during the process in the form of oxide, by a regulated.
supply of comminuted lead; the supplies of air, water and comminuted lead being
regulated with regard to each other.
5. The herein. described. improvement in the art of making white lead, by the >

page_text: agitation of lead in a comminuted state in the presence of water, air and carbonic
acid, the same consisting in carrying on the process at a regulated temperature of
from 75° to 150° Fahr. and under a pressure of from 15 to 30 pounds, substantially
as herein described.
6. The herein described improvement in the art of making white lead, by the
agitation of lead in a comminuted state in the presence of water, air and carbonic
acid, the same consisting in carrying on the process at a regulated temperature of
from 75 to 150 Fahr. and under a pressure of from 15 to 30 pounds, and
preventing by a flow of water, an abnormal rise in such temperature, due to
physical and chemical reactions in the apparatus, substantially as herein described.
7. In a lead corroding apparatus, the combination with the horizontally
arranged revolving cylinder, of a water induction pipe extending in through the
trunnion or axis of the cylinder, and a water eduction pipe extending out through
the trunnion or axis of such cylinder, and having its inner end extending
downwardly from the centre of the cylinder, such pipes being adapted to maintain
a flow of water through the cylinder, for the purpose set forth.
8. In a lead corroding apparatus, the combination with the horizontally
arranged revolving cylinder, of water and gas induction pipes extending in
through the trunnion or axis of the cylinder, and a water eduction pipe extending
out through the trunnion or axis of such cylinder, and having its inner end
extended downwardly from the centre of the cylinder, such pipes being adapted
to maintain a flow of water through the cylinder, for the purpose set forth.
9. In a lead corroding apparatus, the combination with the horizontally
arranged revolving cylinder, of water and gas induction pipes extending in
through the trunnion or axis of the cylinder, and a water and gas eduction pipes,
extending out through the trunnion or axis of the cylinder, the inner end of the
water eduction pipe being extended downwardly from the centre of the cylinder,
such pipes being adapted to maintain a flow of water and gas through the cylinder,
for the purpose set forth.
10. In a lead corroding apparatus, the horizontally arranged revolving cylinder
provided with ribs on its inner periphery, of an oblong square form, arranged a
distance apart, so as to form spaces or cavities of a width nearly equal to that of
the face of the ribs, as described and for the purpose set forth.
11. In a lead corroding apparatus, the combination with the horizontally
arranged revolving cylinder, of water and gas induction pipes extending in through
the trunnion or axis of the cylinder, and a water and gas eduction pipes, extending
out through the trunnion or axis of the cylinder, the downwardly extending
branch pipe 17, and a Y-shaped plug 18, connecting the inner ends of said pipes
together, for the purpose set forth.
12. In a lead corroding apparatus, the combination with the horizontally
arranged revolving cylinder, of an induction pipe or passage extending in through
the axis or trunnion of the cylinder, a rotatable cylinder 26, having peripheral
pockets 32, and a casing enclosing said cylinder, and having communication with
the supply hopper, and the axial induction pipe of the main cylinder, for the
purpose set forth.
13. In a lead corroding apparatus, the combination with the horizontally
arranged revolving cylinder, of an induction pipe or passage extending in through
the axis or trunnion of the cylinder, a rotatable cylinder 26, having peripheral feed
pockets 32, a casing enclosing said cylinder, and having communication with the
supply hopper and the axial induction pipe of the main cylinder, and a means for
imparting intermittent rotation to the feeding cylinder, consisting of the ratchet
wheel 31, pawl 30, arm 29, eccentric rod 28, and eccentric 27, for the purpose
Bet forth.
14. In a lead corroding apparatus, the combination with the horizontally
arranged revolving cylinder, of an induction pipe or passage extending in through
the axis or trunnion of the cylinder, a spiral conveyor arranged to rotate in said

page_text: induction pipe or passage, a rotatable cylinder 26, having peripheral pockets 32,.
and a casing enclosing said cylinder, and having communication with the supply
hopper, and the axial induction pipe of the main cylinder, for the purpose.
set forth.
Dated this 16th day of August 1892.
HERBERT & Co.,
18, Buckingham Street, Strand, London, W.C., Agents to Applicant.