Improvements in the Extraction of Lead, Zinc, Gold, Silver, and other Metals from Sulphides, Refractory or other Ores or Mattes.
Year: 1896

page_text: Date of Application, 9th Oct. 1898
Complete Specification Left 24th July 1897-Accepted. 1st Nov. 1897
Complete Specification Left 24th July 1897-Accepted. 1st Nov., 1897
PROVISIONAL SPECIFICATION.
Improvements in the Extraction of Lead, Zinc, Gold, Silver, and
other Metals from Sulphides, Refractory or other Ores or
Mattes.
JOHN ARMSTRONG, C.E. Consulting Metallurgical Chemist Springfield Park Acton
London, W. do hereby declare the nature of this invention to be as follows:-
or
Carbonate, Bi, Carbonate or Nitrate of Soda or Potash or other alkali,
coal, coke or other carbonaceous matter and lime or other calcareous
substance, are mixed together in certain proportions (varying according
to the nature of the ore) and before or after fusion of these materials in a
furnace, the ore is added (preferably roasted). The furnace is preferably a closed one
and may be provided with a tube- condenser for condensing the vapour emitted
during the reaction when the reduction is completed the furnace is tapped and the
inetals run off, the contents taken out and lixiviated with water whereby the
alkali is recovered to be used over again, the metal is sometimes found in small pellets
in the slag and to recover this, the whole is passed between rollers and washed or
passed over screens or sives and the metals recovered thereby.
and
Dated this 7th day of October 1896.
COMPLETE SPECIFICATION.
Improvements in the Extraction of Lead, Zinc, Gold, Silver, and
other Metals from Sulphides, Refractory or other Ores
Mattes.
I, JOHN ARMSTRONG of Ramlé, Springfield Park, Acton, London, Consulting
Metallurgist, 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 has for its principal object the reduction of complex sulphide ores,
regulus or mattes rich in precious metals but which have hitherto resisted the efforts
of metallurgists to economically extract their valuable metallic constituents.
I add to the raw, or mixed roasted and raw pulverised ore or matte (1) carbonate
such as black ash bicarbonate or nitrate of sodium or potassium, (2) lime chalk or
like salt or compound of lime and (3) carbon, and treat (out of contact of air) in a
inuffle or other furnace such as described later on, which furnace is heated with a
reducing flame. The muffle or furnace may be provided with a condensing tube for

page_text: condensing the emitted vapours. When the re-action is completed, the furnace is
tapped and the charge run off. The lime is now found to have combined with the
silica and the charge separates into three layers, metal at the bottom, a hard layer of
silicate of lime and a soft brittle layer of finely divided zinc, zinc salts and soda salts
mixed. This latter is placed in another closed furnace and the zinc distilled off,
though if a muffle be used in the first instance, by leaving this slag in the muffle
and simply raising the heat it can be distilled off from the reducing furnace. In
such case, the heat is raised to a white heat in this furnace, and the pipe D is bent
down into a condensing chamber, the metallic zinc will then escape in fumes and be
condensed in the condensing chamber. The remaining slag is tapped off and is
lixiviated with water and the alkaline sulphide recovered. This latter can be
reconverted into carbonate in any well known manner, for use in the first operation.
If the slag contain small pellets of metal it can, before lixiviation, be passed through
rollers and treated in sieves to recover the metal.
In order that my invention may be more clearly understood, I append the
accompanying drawing of my apparatus and the description of an actual charge in
which the sulphide ore analysed approximately for metals 25 lead, 25 zinc, and in
which there were about 19 ozs. of silver to the ton.
Figure 1 shows a vertical section, and
Figure 2 a plan.
A is the bed of the furnace, B working holes closed with doors, C tapping holes,
D exit pipe for fuines and waste gases, E admission hopper for charge, F grate, G fire
box, H admission hopper for fuel.
The mode of working is as follows :-
The grate is kept loaded to the top with fuel and the furnace kept at a red heat. The
charge, consisting approximately of 5 of carbon and 30 of carbonate of soda (being
approximately the relative quantities required to produce metallic sodium) and 5 of
lime (to act as flux) to every 100 by weight of ore such as described, is fed in at E
from time to time and acted on by the reducing flame from the fire box G. As the
charge melts, it runs down into the furnace and the metal is from time to time
tapped out.
As the silicate of lime slag accumulates it is also occasionally in part tapped
out and from time to time the remaining zinc and soda slag are either heated to a
white heat in this furnace and the zinc distilled off, or they are run into another
closed furnace where they are treated with metallic copper, the result being that a
brass or bronze is formed and settles down in the bottom, or in place of this the slag
can be strongly heated to nearly a white heat in this second furnace and the zinc
distilled off in the usual manner of distilling zinc. The slag freed from the zinc is
now broken up, or while still hot thrown into water. It is then lixiviated and the
solution of alkaline sulphide treated in any well known manner to form alkaline
carbonate for use in the first operation of the cycle. Or the slag after being run out
of the furnace and allowed to cool, is separated from the metal and the hard insoluble
lime portion by being immersed in water, whereby the soda salts are lixiviated out,
and after the zine has settled, the liquor containing the soda salts is decanted and
the zinc residue is dried and treated either by copper or distilled as herein
stated.
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 process of treating refractory sulphide ores or mattes containing zinc, which
consists in exposing them in a comminuted condition in a reducing furnace or out of
contact of air and at a red heat to the action of lime, and of carbon and an alkali
metal salt such as described (in approximately the proportions used to form alkali
metal when heated out of contact of air) substantially as described.
2. The cycle of operations in the treating of refractory sulphide ores or mattes
containing zinc, which consists in treating them with a calcareous flux, carbon, and

page_text: an alkali metal salt such as described at a red heat, lixiviating the slag containing
the alkali with water so as to extract the alkali metal salts, and from these forming
fresh alkali metal carbonate for use in the first step of the cycle.
3. The process and plant substantially as and for the purposes described in which
the charge of complex ore carbon carbonate or other salt of an alkali metal such as
described and the necessary flux is exposed at a red heat to a strong reducing flame
and the slag and reduced metal separated and the zinc and alkali metal slag treated
in a furnace of much higher temperature so as to recover the zinc substantially as
described.
WM. P. THOMPSON & Co.,
Of Liverpool, Manchester, Birmingham and London, Patent Agents.