Improvements relating to the Manufacture of Carbonate of Lead or White Lead, and to Apparatus therefor.
Year: 1891

page_text: Date of Application, 13th Jan., 1891
Complete Specification Left, 12th Oct., 1891-Accepted, 14th Nov., 1891
PROVISIONAL SPECIFICATION.
Improvements relating to the Manufacture of Carbonate of Lead or
White Lead, and to Apparatus therefor.
We, WILLIAM ASTROP, of 18 Harold Terrace, Hermitage Road, Green Lanes,
in the County of Middlesex, Chemist, and FRANK HERMITAGE PARKER of
Darnley Road, Gravesend, in the County of Kent, Sanitary Agent and Sewage
Manager, do hereby declare the nature of this invention to be as follows:-
Our invention relates to the manufacture of carbonate of lead, better known in
commerce as white lead, and to apparatus for use in such manufacture.
Our said invention is designed to provide for manufacturing white lead more
economically and expeditiously than is practicable by the processes heretofore
adopted, and to obviate the danger to health to which work-people employed in
the manufacture of white lead have hitherto been subjected.
An important feature of our said invention is the treatment of the metallic lead
or pig lead with an alkaline carbonate, such as carbonate of soda or carbonate of
potash, whereby the metallic lead is converted into carbonate of lead.
In carrying our invention into practice, we first dry and afterwards fuse the
required quantity of the alkaline carbonate, and melt the metallic lead; and we
then mix the molten lead with the alkali whilst the latter is in a state of fusion.
For this purpose we find it advantageous to employ suitable furnaces provided
with any required number of caldrons according to the quantity of material to be
treated.
When the materials are thoroughly mixed and the whole of the metallic lead has
been taken up by the alkali, the melting pot should be. lifted out of the furnace
by suitable over-head travelling-gear, or other convenient means, and the whole of
the melted mass should be thrown or poured out and spread upon a floor, which
should be paved or cemented. The mass is then allowed to cool, and as soon as it
is cold, it absorbs carbonic acid gas from the atmosphere, the vehicle being the
alkali. It should then be sprinkled occasionally for about forty-eight hours (more
or less) with water in the form of spray or otherwise, and then be thrown into a
large tank and washed. It is then filtered to separate the carbonate of lead from
the water, and all the washing waters and drainings are conveyed to suitable pans
or tanks, which are heated by exhaust steam or other suitable means, for the purpose
of crystallizing and recovering the alkali, which can be used over and over again
without any detriment to the chemical action. The white lead is then removed
from the filters and spread, on a drying floor, which may be warmed and provided
with an exhaust fan or blowing fan for ensuring the rapid drying of the white
lead.
The product of our process is friable and does not require any grinding. There
are no noxious vapours arising during its manufacture and it need not be touched
by the hands; its manufacture is therefore not at all detrimental to health.
By subjecting the molten mass to the action of the atmosphere as above described,
I am enabled to conveniently recover the alkali, as it absorbs from the atmosphere
a quantity of carbonic acid gas approximately equivalent to that which was taken
from it to combine with the lead.
It is evident, therefore, that our process can be carried on at a very low cost.
100
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicants.

page_text: COMPLETE SPECIFICATION.
Improvements relating to the Manufacture of Carbonate of Lead or
White Lead, and to Apparatus therefor.
We, WILLIAM ASTROP of 18 Harold Terrace Hermitage Road Green Lanes
in the County of Middlesex, Chemist and FRANK HERMITAGE PARKER of
Darnley Road Gravesend in the County of Kent, Sanitary Agent and Sewage
Manager 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 :-
Our invention relates to the manufacture of carbonate of lead known in commerce
as white lead, and to apparatus for use in such manufacture.
Our said invention is designed to provide for manufacturing white lead more
economically and expeditiously than is practicable by the processes heretofore
adopted and to obviate the danger to health to which work-people employed in the
manufacture of white lead have hitherto been subjected.
An important feature of our said invention is the treatment of metallic lead or
pig lead with an alkaline carbonate, such as carbonate of soda or carbonate of
potash, whereby the metallic lead is converted into carbonate of lead.
In carrying our invention into practice, we first dry and afterwards fuse the
required quantity of the alkaline carbonate, and we melt the metallic lead; we
then mix the molten lead with the said alkali whilst the latter is in a state of fusion.
For this purpose we find it advantageous to employ suitable furnaces provided
with any required number of caldrons according to the quantity of material to be
treated.
When the materials are thoroughly mixed and the whole of the metallic lead
has been taken up by the alkali, the melting pot should be lifted out of the furnace
by suitable overhead travelling gear, or other convenient means, and the whole of
the melted mass should be thrown or poured out and spread upon a floor, which
should be paved or cemented. The mass is then allowed to cool, and as soon as it
is cold, it absorbs carbonic acid gas from the atmosphere the vehicle being the
alkali. By sprinkling the mass occasionally with water in the form of spray or
otherwise for about forty eight hours (more or less) the absorption of carbonic acid
by the lead from the atmosphere is greatly facilitated and any granular lead
existing in the mass is reduced to the condition of fine powder.
The mass is next thrown into a large tank and washed. It is then filtered to
separate the carbonate of lead from the water, and all the washing waters and
drainings are conveyed to suitable pans or tanks which are heated by exhaust steam
or other suitable means for the purpose of crystallizing and recovering the alkali,
which can be used over and over again without any detriment to the chemical
action. The white lead is then removed from the filters and spread on a drying
floor, which may be warmed and provided with an exhaust fan or blowing fan for
ensuring the rapid drying of the white lead.
The product of our process is friable and does not require any grinding. There
are no noxious vapours arising during its manufacture, and it need not be touched
by the hands; its manufacture is therefore not at all detrimental to health.
By subjecting the molten mass to the action of the atmosphere as above described,
we are enabled to conveniently recover the alkali, as it, like the lead, absorbs from
the atmospheric carbonic acid gas and is thereby regenerated. The quantity of
carbonic acid gas so absorbed by the alkali is approximately equivalent to that
which was taken from it to combine with the lead and the said alkali may be used
again.
It is evident, therefore, that our process can be carried on at a very low cost.

page_text: Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
First. In the manufacture of carbonate of lead or white lead the employment of
a fused alkaline carbonate, substantially as, and for the purpose specified.
Second. In the manufacture of white lead or carbonate of lead exposing a
mixture consisting of metallic lead and an alkali to the influence of the air for the
purposes specified.
Third. In the manufacture of white lead or carbonate of lead according to our
improved process sprinkling the mass of lead and alkali with water for the purposes
specified.
Fourth. In the process for the manufacture of white lead or carbonate of lead
herein described, the recovery and regeneration of the alkali employed for the
purposes specified.
Fifth. The process for the manufacture of white lead or carbonate of lead,
substantially as herein before described.
Dated this 12th day of October 1891.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicants.