Improvements in and relating to the Manufacture of Lead from its Ores or Compounds.
Year: 1888

page_text: Date of Application, 5th Oct., 1888
Complete Specification Left, 2nd Aug., 1889-Accepted, 7th Sept., 1889
PROVISIONAL SPECIFICATION.
Improvements in and relating to the Manufacture of Lead from its
Ores or Compounds.
I, CHARLES HENRI THEODORE HAVEMANN of 5 Passage Saulnier, Paris, France,
Merchant, do hereby declare the nature of this invention to be as follows:-.
My invention has reference to the manufacture or obtaining of lead from its ores or
compounds with sulphur and it consists in fusing the ores or compounds with caustic
soda or carbonate of soda or a mixture of the two, and in regenerating the spent soda
into carbonate or caustic soda so that it may be used again for the reduction of a
further quantity of lead ore or compound.
Caustic soda is to be preferred to the carbonate because it not only contains a
larger percentage of oxide of sodium (Na, O) than any other sodium salt but its
hydrogen which during the reaction is set free combines with the sulphur and
escapes as sulphuretted hydrogen; consequently the soda is not so quickly
converted into sulphide of sodium (which has no further reducing power) or in other
words much less caustic soda is required than carbonate for a given amount of work.
If carbonate of soda alone is used a percentage of the lead combines with the soda
and therefore a double compound of lead and sodium is formed. To prevent this I
add a small proportion say 10 per cent. more or less of iron.
I regenerate the spent soda or slag in one of several ways. I can expose it in its
solid state and in lumps to a stream of carbonic acid so that the slag is decomposed
and consequently pulverized. I then dissolve it in water the liquor being a solution
of carbonate of soda which can then be causticized in the usual manner if caustic
soda be required. Or 1 can dissolve the spent soda or slag in water and then add
sufficient bicarbonate of soda to the liquor to cause the sulphur in the slag to escape
as sulphuretted hydrogen; I can then causticize the liquor.
It is not at all necessary to go to the expense of concentrating the liquor thus
obtained from the spent soda or slag so that it shall contain a large percentage of
soda; it can be used without concentration if it be run into the furnace upon
lead ore or compound previously charged therein; the surplus water will quickly
evaporate.
As has been already stated a mixture of caustic soda and carbonate of soda can be
used; this will lead to considerable economy because the soda, which is obtained as
a waste product in the manufacture of sodium from its caustic compounds, consists of
carbonate of soda and caustic soda and is adapted for the purpose of my invention.
I am aware that carbonate of soda has been used as a flux and reducing agent
in the assaying of lead ores but it has not hitherto been employed for the production
of lead on a commercial scale because the expense as compared with other processes
has been too great. But by means of my invention whereby, as part of the general
process of obtaining lead from its ores or compounds on a commercial scale, I
regenerate the spent soda at a small cost and use it again for the reduction of a
further quantity of lead ore or compound, the employment of soda in the manufacture
It enables
of lead from its ores or sulphur compounds becomes a practical success.
me to obtain the same percentage of lead (and silver) as is obtained in the dry way of
assaying and thus save at least per cent. of lead (including the silver) as compared
with other commercial processes.
Dated this 5th day of October 1888.
J. C. MEW DURA,
169, Fleet Street, London, Agent.

page_text: COMPLETE SPECIFICATION.
Improvements in and relating to the Manufacture of Lead from its
Ores or Compounds:
I, CHARLES HENRI THEODORE HAVEMANN, of 5, Passage Saulnier, Paris in the
republic of France, Merchant, 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:-
My invention relates to the production of lead from galena or other sulphuretted
ores or compounds containing the same, and it consists in fusing such ores or
compounds with caustic alkali or equivalent alkaline compounds or mixtures, and in
regenerating the spent alkali, so that it may be again used for the reduction of a
further quantity of ore or compound.
I will first describe my invention with reference to the use of caustic soda only,
but it is to be understood that other sodium compounds and similar potassium
compounds can be used.
1 prefer to use caustic soda for effecting the reduction, because it not only contains
a larger percentage of oxide of sodium (Na, 0) than any other sodium salt, but its
hydrogen, which during the reaction is set free, combines with a proportion of the
sulphur and escapes as sulphuretted hydrogen; consequently the soda is not so quickly
converted into sulphide of sodium (which has no further reducing power) or in
other words, a much smaller proportion of caustic soda is required for reducing a given
amount of ore or compound than of any other sodium salt.
If carbonate of soda were used a percentage of the lead would combine with the
soda and form a double compound of lead and sodium, unless a small proportion, say
10 per cent. more or less, of iron were added.
In carrying out my invention I introduce the lead ore or compound into a
reverberatory or other furnace, or a pot or crucible, with a suitable proportion of
caustic soda, say 25 per cent. more or less by weight of the ore or compound under
treatment, and reduce the same to a liquid state. In this condition the soda com-
bines with the sulphur and other impurities to form a slag, whilst the lead is reduced
to a metallic state and may be drawn off.
•
I regenerate the spent soda or slag in one of several ways. According to one
method I expose it in its solid, state and in lumps to a stream of carbonic acid, so
that the slag is decomposed and consequently pulverized. I then dissolve it in water,
the liquor being a solution of carbonate of soda which can be causticized in the usual
manner, if caustic soda be required. According to another method I dissolve the
spent soda or slag in water and then add sufficient bi-carbonate of soda to the liquor
to cause the sulphur in the slag to escape as sulphuretted hydrogen. The same result
can, however, be obtained by passing carbonic acid gas through the liquor; I can
then cauticize the liquor.
It is not necessary to go to the expense of concentrating the liquor thus obtained
from the spent soda or slag, so that it shall contain a large percentage of soda, as it
can be used without concentration, if it be run into the furnace upon lead ore or
compound previously charged therein, the surplus water being quickly evaporated.
As has been already indicated, a compound of caustic soda and carbonate of soda
can be used for effecting the reduction, and this will lead to considerable economy,
because the soda, which is obtained as a waste product in the manufacture of sodium
froin its caustic compounds, consists of carbonate of soda and caustic soda, and is
adapted for the purpose of my invention.
I am aware that carbonate of soda has been used as a flux and reducing agent in
the assaying of lead ores, but it has not hitherto been employed for the production of
lead on a commercial scale because the expense, as compared with other processes,
has been too great. But by means of my invention, whereby, as part of the general
process of obtaining lead from its ores or compounds on a commercial scale, I
regenerate the spent soda at a small cost and use it again for the reduction of a

page_text: further quantity of lead ore or compound, the employment of soda in the manufacture
of lead from its ores or sulphur compounds becomes a practical success. It enables
ine to obtain the same percentage of lead as is obtained by the dry process of assaying,
and thus produce say 6 per cent. more lead than can be obtained by any other
commercial process.
It is to be understood that, if any silver is present in the ore; it will be reduced
with the lead, from which it can be subsequently separated by any suitable means.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
The process consisting in treating ore or compound containing lead, with caustic
alkali or equivalent alkaline compounds and regenerating the alkali so that it will
be again available for use, substantially as hereinbefore described.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.