IMPROVEMENTS IN THE PROCESS OF DESILVERIZING AURIFEROUS AND ARGENTIFEROUS LEAD, AND IN TREATING THE RESIDUAL PRODUCTS ARISING THEREFROM
Year: 1879

page_text: LETTERS PATENT to Alfred Vincent Newton, of the Office for Patents, 66,
Chancery Lane, in the County of Middlesex, Mechanical Draughtsman, for the
Invention of "IMPROVEMENTS IN THE PROCESS OF DESILVERIZING AURIFEROUS
AND ARGENTIFEROUS LEAD, AND IN TREATING THE RESIDUAL PRODUCTS ARISING
THEREFROM." A communication from abroad by Alexandre Marin y Garcia,
of Aguilas, in the Kingdom of Spain.
Sealed the 16th September 1879, in pursuance of an Order of the Lord Chancellor,
and dated the 21st February 1879.
PROVISIONAL SPECIFICATION left by the said Alfred Vincent Newton at
the Office of the Commissioners of Patents on the 21st February 1879.
ALFRED VINCENT NEWTON, of the Office for Patents, 66, Chancery Lane, in the
County of Middlesex, Mechanical Draughtsman. "IMPROVEMENTS IN THE PROCESS
OF DESILVERIZING AURIFEROUS AND ARGENTIFEROUS LEAD, AND IN TREATING THE
RESIDUAL PRODUCTS ARISING THEREFROM." [A communication from abroad by
Alexandre Marin y Garcia, of Aguilas, in the Kingdom of Spain.]
The process for desilverizing auriferous and argentiferous lead is conducted as
usual by the introduction of metallic zinc or spelter into the fused lead after
cleaning the bath from antimony, iron, and other impurities by discharging air
under pressure into the bath.
The compressed air is introduced into the lead pan by a metallic pipe vertically
disposed in the centre of the said pan at a few inches from the bottom, and connected
with a force pump which will deliver the air at a pressure of about two and half
atmospheres.
The scums thrown up by the action of the air are the oxides of antimony and
iron mixed with lead-oxide, and may be termed oxides No. 1, and will be treated
as hereafter explained.
The introduction of zinc or spelter into the lead produces rich scums, which are
alloys of lead, zinc, and silver, the proportion of zinc is '/rd approximately of the
seums, and nearly the whole silver of the argentiferous lead is concentrated in
them.
These rich scums are subjected to the action of a blast of air by apparatus
similar to that above described, and are converted into fine oxides of lead and zinc,

page_text: the silver remaining unoxidysed, but intermixed in the whole mass. This oxidation
must be thoroughly effected to ensure the complete success of the process. These
scums resulting from this operation may be termed oxides No. 2.
The lead which has given its silver to the rich scums or to the oxides No. 2 is
contaminated with zinc, to remove which the metal is treated with a blast of air as
before described; the result will be, first, zinc scums which may be used for a new
desilverizing operation, and. poor, oxides of lead mixed with oxides of zinc, which
may be termed oxides No. 3. The poor lead is cast into pigs, and is ready for the
market as soft lead..
The metallurgical treatment of the three kinds of oxides, Nos. 1, 2, and 3, is as
follows:-
The oxides No. 1 finely powdered are dissolved in concentrated vinegar (acetic
acid, pyrolignous acid), the antimonial yellow oxide remaining in suspension,
and leaving the silver, if any, in the bottom of the vessel. By filtration the
antimonial oxide is completely separated, and there results a solution of acetate of
lead.
The oxides No. 2, containing nearly all the silver of the lead, are treated in the
same way by a solution of concentrated vinegar, the same being actively stirred.
The silver deposits on the bottom of the vessel; meanwhile the oxides of load and
zinc dissolve completely as acetates of lead and zinc in the same manner as in the
precedent case of No. 1 oxides.
The silver is collected in the form of a fine metallic gray powder, washed in clean
wator, refined in graphite crucibles, and moulded into ingots. The doublo acetate
of lead and zinc is added to the acetate of lead obtained from oxide No. 1. With
this operation the cupellation process is avoided with. all its difficulties, loss of silver,
and lead.
The oxides No. 3, poor in silver, are subjected to the same treatment, i.e.,
dissolved in concentrated vinegar separated into two products, some silver, which
deposits in the bottom of the vessel, and the double acetate of lead and zinc. The
silver is collected with the silver of the oxido No. 2, and the acetates are added to
the other acetates.
Having in the said manner obtained the moulding of the soft lead and the
separation of the silver, which are the two most important operations of the
desilverizing process, it remains only to utilise the secondary products, i.e., the
antimonal oxide and the double acetate of lead and zinc.
The antimonial oxide is a yellow pigment, a use for which will no doubt be
readily found.
The double acetate of lead and zinc can receive various treatments for its further
utilization. Thus by crystallization sugar of lead can be obtained, and the mother
liquor containing the acetate of zinc can be treated for white zinc by precipitating
the metal with carbonate of soda, or the whole liquid may be treated with carbonate
of soda to obtain white lead with some zinc white in it.
The carbonates of potash and lime give the same result, but as the acetate of soda
is the matter out of which the acetic acid is generally extracted it seems preferable
to use the carbonate of soda. The result of the precipitation by the reactive is
acetate of soda, which will be crystallized; it forms a commercial salt to be sent
to the market.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alfred Vincent Newton in the Great Seal Patent Office on the 16th
September 1879.
ALFRED VINCENT NEWTON, of the Office for Patents, 66, Chancery Lane, in the
County of Middlesex, Mechanical Draughtsman, "IMPROVEMENTS IN THE PROCESS
OF DESILVERIZING AURIFEROUS AND ARGENTIFEROUS LEAD, AND IN TREATING THE
RESIDUAL PRODUCTS ARISING THEREFROM." A communication from abroad by
Alexandre Marin y Garcia, of Aguilas, in the Kingdom of Spain.
The object of this Invention is to treat auriferous and argentiferous lead in such
a manner as to effect a great economy in the process, not merely by obtaining a
larger per centage of the silver, but also by converting the bye products into valuable
commercial substances.
The process for desilverizing auriferous and argentiferous lead is conducted as
usual by the introduction of metallic zinc or spelter into the fused. lead after
cleaning the bath from, antimony, iron; and other impurities by discharging air
under pressure into the bath.
The compressed air is introduced into the lead pan by a metallic pipe vertically
disposed in the centre of the said pan at a few inches from the bottom, and con-
nected with a force pump which will deliver the air at a pressure of about two
and a half atmospheres.
The scums thrown up by the action of the air are the oxides of antimony and
iron mixed with lead oxide, and may be termed oxides No. 1, and will be treated
as hereafter explained.
The introduction of zinc or spelter into the lead produces rich scums, which are
alloys of lead, zinc, and silver. The proportion of zinc is one third approximately
of the scums; and nearly the whole silver of the argentiferous lead is concentrated
in them. This proportion belongs to, the scum after liquation; i.e., after separating
at a low temperature (three hundred degrees to three hundred and fifty degrees
centigrade) the exceeding lead.
These rich scums are subjected to the action of a blast of air by apparatus, similar
to that above described, and are converted into fine oxides of lead and zinc, the
silver remaining unoxidized, but intermixed in the whole mass. This oxidation
must be thoroughly effected to ensure the complete success of the process. The
scums resulting from this operation, which scums may if necessary, be reduced, by
pulverization to a fine powder, may be termed oxides No. 2. The lead which has
given its silver to the rich scums, or to the oxides No.. 2 is contaminated with zinc,
to remove which the metal is treated with a blast of air as, before described; the
result will be, first, zinc scums which may be used for a new. desilverizing operation,
and poor oxides of lead mixed with oxides of zinc, which may be termed oxides
No. 3.
The poor lead is cast into pigs, and is ready for the market as soft lead
The above described process of desilverizing lead differs from that in common use
by the employment of the air blast.
The metallurgical treatment of the three kinds of oxides Nos. 1, 2, and 3, is as
follows:-The oxides No. 1 finely powdered are dissolved in concentrated vinegar
(acetic acid or pyroligneous acid), the antimonial yellow oxide remaining in
suspension, and the silver, if any, depositing in the bottom of the vessel. By
filtration the antimonial oxide is completely separated, and there results a solution
of acetate of lead.
The oxides No. 2 containing nearly all the silver of the lead are treated in the
same way by a solution of concentrated vinegar, the same being actively stirred.
The silver deposits on the bottom of the vessel, meanwhile the oxides of lead and
zine dissolve completely as acetates of lead and zinc in the same manner as in the
precedent case of No. 1 oxides.

page_text: The silver is next collected in the form of a fine metallic grey powder, washed in
clean water, refined in graphite. crucibles, and finally moulded into ingots. The
double acetate of lead and zinc is added to the acetate of lead obtained from oxides
No. 1. With this operation the cupellation process is avoided with all its
difficulties, loss of silver, and lead.
The oxides No. 3, poor in silver, are subjected to the same treatment, i.e.,
dissolved in concentrated vinegar and separated into two products, some silver
which deposits on the bottom of the vessel, and the double acetate of lead and zinc.
The silver is collected and added to the silver of the oxides No. 2, and the acetates
are added to the other acetates.
Having in the manner above described obtained the soft lead, and converted it
into pigs, and effected the separation of the silver, which are the two most im-
portant operations of the desilverizing process, it remains only to utilize the
secondary products, i.e., the antimonial oxide and the double acetate of lead and
zinc.
The antimonial oxide is a yellow pigment, a use for which will no doubt be
readily found.
The double acetate of lead and zinc can receive various treatments for its further
utilization. Thus by crystallization sugar of lead can be obtained, and the mother
liquor containing the acetate of zinc can be treated for zinc-white by precipitating
the metal with carbonate of soda, or the whole liquid may be treated with
carbonate of soda to obtain white lead with some zinc-white in admixture
therewith.
The carbonates of potash and lime give the same result, but as the acetate of
Foda is the matter out of which the acetic acid is generally extracted it seems
preferable to use the carbonate of soda. The result of the precipitation by the
reactive agent is acetate of soda which will be crystallized; it forms a commercial
salt suitable for the market.
Having now set forth the nature of the Invention of "Improvements in the
Process of Desilverizing Auriferous and Argentiferous Lead, and in Treating the
Residual Products arising therefrom," as communicated to me from abroad, and
explained the manner of carrying the same into effect, I wish it to be understood
that under the above in part recited Letters Patent I claim,-
First. The employment of air blasts in the manner and for the purpose above
described.
Secondly. The use of concentrated vinegar, acetic or pyroligneous acid, for
dissolving the oxides formed as above explained and freeing therefrom the contained
silver.
Thirdly. The manufacture of acetate of lead, white lead, and zinc-white, by the
use of carbonate of soda or other alkaline carbonates or oxides, and also the produc-
tion of acetate of soda as a bye product in the manner above set forth.
In witness whereof, I, the said Alfred Vincent Newton, have hereunto set
my hand and seal, the Sixteenth day of September, in the year of our
Lord One thousand eight hundred and seventy nine.
A V. NEWTON.
(L.B.)