Process for the Manufacture of White Lead and for the Recovery of Sulver in said Process.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
Process for the Manufacture of White Lead and for the Recovery of
Sulver in said Process.
ANDREW CHARLES JOSEPH CHARLIER, Masterton Works, Keppochhill Road,
Glasgow, Chemist, do hereby declare the nature of this invention, and in what
manner the same is to be performed, to be as follows:-
This invention which relates to a process for the manufacture of white lead
and for the recovery or suiver in said process, has for its object to manufacture
a basic carbonate or white lead direct rom metallic lead, instead of having as at
present to employ an oxide of lead which must hrst be dissolved in an acid
or alkali in waion in may be soluble before passing the carbonic acid gas to
convert and precipitate it as white lead. Even in the old Dutch or corrosive
process, acetic aciu is employed, but I now propose to make the basic carbonate
of white lead direct from the metallic lead without using any solvent whatsoever,
and this I do by the passing of moist carbonic acid gas through it when in a
molten condition, and at a certain temperature.
I hnd that if metallic lead be heated strongly without air, it will volatilize
and afterwards condense again as metallic lead, but in a very fine state of division,
and in the same way if molten lead be heated to a temperature just below
fusing point, in the presence of moist carbonic acid, a basic carbonate of white
lead is at once formed and collected in suitable water condensers. By this process
also metallic lead containing silver can be successfully treated; the lead being
converted into carbonate, and the silver remains in the melting pot, and can be
recovered as Boon as a sufficient quantity has accumulated. Care only must be
taken not to allow the heat to reach the volatilizing point of silver.
The method I adopt is as follows:
1 do not contine myself to any particular melting pot. I prefer however, to
work with one as shallow as possible, and which can be made of either iron,
firebrick or other suitable substance which will stand the working temperature
required. The melting pot must be fitted with a cover which must be perfectly
air tight; the only opening being connected up with the condensers for carrying
away the white lead as formed. Suitable means must also be employed for keeping
the molten lead thoroughly agitated during the process, so as to allow every
particle to come into contact with the moist carbonic acid gas, which is passed
through a pipe into the pot. The pan is heated by a fire underneath, and wlien
the proper temperature is obtained, molten lead is fed into the pan at regular
intervals, whilst a stream of moist carbonic acid gas is then passed through it
converting it into basic carbonate of white lead, which is collected in water
condensers.
The amount of hydrate of lead contained in the white lead is regulated
primarily by the temperature employed in the process, and in order to obtain a
true basic carbonate. I prefer to work at a temperature of about 800″ 1º.

page_text: If metallic lead containing silver is used, the pans must be cleaned out at
certain intervals, and the silver be found at the bottom of the pans.
Dated this 9th day of January 1899.
Process for the Manufacture of White Lead and for the Recovery of
Silver in said Process.
ANDREW CHARLES JOSEPH CHARLIER, Masterton Works, Keppochhill Road,
Glasgow, Chemist, 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:-
This invention relates to a process for the manufacture of white lead and for the
recovery of silver in said process.
The object of my invention is to manufacture a basic carbonate of white lead
direct from metallic lead, instead of having as at present to employ an oxide of
lead which must first be dissolved in an acid or alkali in which it may be soluble
before passing the carbonic acid gas to convert and precipitate it as white lead.
Even in the old Dutch or corrosive process, acetic acid is employed, but I now
propose to make the basic carbonate of white lead direct from the metallic lead
without using any solvent whatsoever, and this I do by the passing of moist
carbonic acid gas through it when in a molten condition, and at a certain tem-
perature, which I prefer to keep at about 800 degrees Fahrenheit.
I find that if metallic lead be heated strongly without air, it will volatilise and
afterwards condense again as metallic lead, but in a very fine state of division, and
in the same way if molten lead be heated to a temperature below flaking point
in the presence of moist carbonic acid, a basic carbonate of white lead is at once
volatilised and collected in suitable condensers. By this process also metallic
lead containing silver can be successfully treated; the lead being converted into
carbonate, and, the silver remaining in the melting pot, and can be recovered as
soon as sufficient quantity has accumulated. Care only must be taken not to
allow the heat to reach the volatilising point of silver.
The method I adopt is as follows:-
I do not confine myself to any particular pan. I prefer however, to work with
one as shallow as possible and which can be made either of iron or firebrick, or
other suitable substance which will stand the working temperature required. The
pan must be fitted with a cover which must be perfectly air-tight; the only
opening being connected up with the condensers for carrying away the white lead
as formed. Suitable means must also be employed for keeping the molten lead
thoroughly agitated during the process, so as to allow every particle to come into
contact with the moist carbonic acid gas, which is passed through tuyeres into
рап. The pan is heated by a fire underneath, and the proper temperature being
obtained, molten lead is fed into the pan at regular intervals, whilst a stream of
moist carbonic acid gas is then passed through it converting it into basic carbonate
of white lead, which is collected in suitable condensers.
the
The amount of hydrate of lead contained in the basic carbonate of white lead is
regulated primarily by the temperature.
If metallic lead containing silver be used, the pans must be cleaned out at
certain intervals, and the silver will be found at the bottom of the pan.

page_text: Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:-
1. The production of basic carbonate of lead direct from molten lead under
certain conditions as hereinbefore described and by passing through or over it
moist carbonio acid gas.
2. The using of molten lead containing silver under the conditions as herein-
before described, the lead being converted into a basic carbonate of lead, and
the silver remaining in the pan and recovered as pure silver.
Dated this oth day of October 1899.
JOHNSONS,
Applicant's Agents, 115, St. Vincent' Street, Glasgow.