IMPROVEMENTS IN EXTRACTING SILVER FROM LEAD
Year: 1864

page_text: PROVISIONAL SPECIFICATION left by Adolphe Moreau at the Office
of the Commissioners of Patents, with his Petition, on the 8th
November 1864.-A communication from abroad by Don Francisco
Marques Millan del Real, of No. 7, Rue Mautrec, Bordeaux, in the
Empire of France, Engineer.
I, ADOLPHE MOREAU, of Chancery Lane, in the County of Middlesex,
'do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
EXTRACTING SILVER FROM LEAD," to be as follows:
This Invention has for its object improvements in extracting silver from
lead. For this purpose lead from which the silver is desired to be extracted
is run from the reverberatory furnace into a heating pan or pans, under which
a strong fire has been previously made, in order that no cooling of the lead
may take place, but that its temperature may be raised in a short timė. The
surface of the lead is then skimmed, after which I introduce about 1 part by
weight of carbonate of ammonia to every 100,000 parts by weight of lead
contained in the heating pan. The instrument I employ for the purpose of
introducing the carbonate of ammonia into the lead is in the form of a ladle,
having a lid thereto. The entire surface of this instrument is perforated with
small holes, and the lid is provided with a spring catch by which it is
fastened down. This instrument, with the carbonate of ammonia therein, is
stirred about in the lead for about 5 minutes, when it is withdrawn, and a
similar instrument containing about 1 part by weight of sea salt to about
10,000 parts by weight of lead is introduced into the lead. This instrument

page_text: is well stirred in the lead for about 10 minutes. If the quantity of silver
contained in the lead is very high, then a proportionally greater quantity of sea
salt is introduced. The surface of the lead is next skimmed, and the pro-
ducts of this skimming are placed in small heaps ready to be placed, as
hereafter described, in a close retort, having a condensation chamber or
chambers connected therewith by suitable passages. After this skimming is
completed about 1 per cent. of zinc is introduced into the remaining lead in
an instrument similar to that used for introducing the sea salt and carbonate
of ammonia. The instrument containing the zinc is well stirred in the lead
for about 5 minutes each time. It is introduced until the desired quantity of
zinc has been added to the lead. The fire is then withdrawn from under the
heating vessel containing the lead, and the door of the furnace is left open in
order that the lead may be cooled as quickly as possible. Directly the
surface of the lead presents a slightly crystalline appearance, this crystallized
part is removed and placed in small heaps, which are then placed without
delay in the retort already referred to, in the following manner :-I first place
on the bottom of the retort a layer of vegetable charcoal broken into small
pieces; upon this the crystallized matter is placed, which is next covered with a
layer of charcoal. The door of the retort is then hermetically closed, and a
fierce fire is made in a furnace under the retort. After maintaining this fire
for about 2 hours, the zinc which was contained in the silver and lead intro-
duced into the retort will be found in the chambers of condensation in
connection with the retort in the state of oxide of zinc. When the distillation
is completed, which may be readily ascertained by looking through a door
into the condensation chamber, the retort is opened and the product of the
second skimming introduced in order to combine it with the silver contained
in the retort. The door is then closed for about 10 minutes, after which the
rich lead is drawn off from the retort into a pot, from which it is taken to be
refined. It will be found that all the silver contained in the lead (excepting
about 1 to 2 parts of silver to every 10,000 parts of lead) is found reduced
to a small volume, with sufficient lead for its cupellation. Directly the crys-
tallized matters resulting from the third skimming have been introduced into
the retort, the lead remaining in the heating pans or vessels is run off into a
reverberatory furnace, where it is kept under the action of a fierce fire for
about 3 hours. It is then drawn off, and cast in suitable moulds.