Improvements in the Treatment of Lead Ores.
Year: 1898

page_text: Date of Application, 3rd Jan., 1898-Accepted, 5th Mar., 1898
COMPLETE SPECIFICATION.
Improvements in the Treatment of Lead Ores.
I, ALICE PIGOTT, of Archer Lodge, Charles Road, St. Leonards, in the County of
Sussex, Married Woman, do hereby declare the nature of this invention and in
what manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement:
-
In my Specification No. 2883 of 1893 (taken in my maiden name Macdonald) I
described the treatment of galena for the production of lead, lead sulphate, and lead
oxide. My present invention relates to modifications of the processes described
in the previous specification whereby I am enabled to produce and deal with certain
new lead compounds.
For this purpose, galena or lead sulphide is melted either alone or along with
lead, or is dissolved in a bath of molten lead, and a current of air is forced
through the molten bath volatilising the galena.
Into this vapour or fume, after it has left the melting bath, a further quantity of
air or oxygen, or air and steam is blown, causing the vapour to burn and to become
oxidised to an oxisulphide having a formula between P3 S2 Os and Pl³ S² O⁹.
Instead of employing air to volatilise the galena, a highly heated non-oxidising
gas such as hydrogen, nitrogen, hydrocarbon gas, carbonic oxide, or carbon dioxide,
steam, water gas or mixtures of these may in the first instance be forced through
the molten material, the air, or oxygen, or air and steam being afterwards blown
into the galena vapour to oxidise it and form the compound P63 S2 08 or, with
great excess of air, Pb³ S2 0° above referred to.
In order to obtain thorough oxidation, it is necessary that the vapour into which
the air is blown should be entirely separated from such drops or spray of the liquid
bath as may be thrown up by blowing through the liquid, and therefore it is of
advantage to oxidise the vapour in a separate combustion chamber, sufficiently far
from the liquid to prevent any of it from splashing into the oxidising current.
While the galena is volatilised whether by air or by other gaseous fluid, such
silver as may be present in the lead or galena remains behind.
When air is passed through the molten bath, a certain proportion of metallic
lead is produced and remains in the bath holding the silver.
In order to fully concentrate the silver, sulphur may be added to this remaining
lead and the blowing continued, to volatilise it as described in my previous
specification above referred to.
When non-oxidising gas is passed through the bath, no metallic lead is pro-
duced and the concentration of the silver may be conducted without the addition
of sulphur.
The galena vapour, volatilised by non-oxidising gas, instead of being oxidised,
may be condensed and collected as pure galena or may be passed through molten
litharge whereby metallic lead is produced and sulphur dioxide is evolved.
The highly heated non-oxidising gas for volatilising the galena may be obtained
by blowing air, or air and steam, through incandescent coke.
The oxisulphide obtained by oxidising the galena vapour may be added to mineral
calena heated to a temperature not under 1,000° C. and agitated and kept hot

page_text: preferably by hot gas or steam or by air blown through it; metallic lead is thus
produced and sulphur dioxide is evolved according to the equations ;-
2PbSPb³S²0° = 5Pb + 4S02
-
5PbS+2Pb³S20°
=
11Pb + 980%
which reactions usually take place simultaneously owing to the oxisulphide being
composed of a mixture of P63 S2 08 and Pb³ S² Ŏº.
When the oxisulphide is added to the heated galena somewhat in excess, a little
litharge is produced and the lead obtained is of great purity and softness.. The
whole of the lead, as well as the oxisulphide, can be converted into litharge and
sulphur dioxide by melting the lead in a basic lined vessel, agitating and keeping
it hot by a current of hot gas or steam or by air, and adding the oxisulphide,
when reaction takes place according to the equations:-
In carrying on this process it is advisable to leave a portion of the lead unoxidised,
as this retains such silver as may be present.
The process above described for producing the oxisulphide is applicable to lead
ores or galena containing refractory ingredients such as zinc blende. When this
is added to the agitated bath of galena or lead the zinc blende is separated as cinder.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:-
---
1. The herein described process for production of oxisulphides of lead having
the formulae P3 S2 08 and P63 S2 09 by melting galena or lead sulphide with or
without lead, volatilising the galena by blowing air or hot non oxidising gas through
the molten material and blowing air or air and steam through the galena vapour.
2. The herein described process for producing lead and sulphur dioxide by adding
to molten galena, while agitating and maintaining the heat, the oxisul-
phides P63 S 08 or P63 S2 0° or a mixture of these obtained as above set forth.
3. The herein described process for producing litharge and sulphur dioxide by
melting lead and adding, while agitating and maintaining the temperature, the
oxisulphides P6³ S³ 08 or Pb³ $2 09 or a mixture of these obtained as above set
forth.
4. The herein described process for concentrating the silver contained in lead
or galena by melting the galena with or without lead and blowing hot non-oxidising
gas through the molten material.
5. The herein described process for producing lead and sulphur dioxide by melt-
ing galena with or without lead, volatilising the galena by blowing hot non-
oxidising gas through the molten material, and passing the galena vapour through
molten litharge.
Dated this 2nd day of Tonuo 1000
ABEL & IMRAY,
Agents for the Applicant.