An Improved Process for the Treatment of Sulphurous Ores containing Arsenic, Antimony or Tellurium.
Year: 1898

page_text: [Communicated from abroad by ELIAS PETERSSON, of No. 32, Avenue de la
Couronne, Brussels, in the Kingdom of Belgium, Engineer.]
An Improved Process for the Treatment of Sulphurous Ores
containing Arsenic, Antimony, or Tellurium.
I, WILLIAM THOMAS WHITEMAN, of No. 7, Staple Inn, in the County of
Middlesex, Patent Agent, do hereby declare the nature of this invention to be
as follows:-
This invention consists in a process of treatment of sulphurous ores containing
arsenic, antimony or tellurium, whether for extracting these metals therefrom,
or for rendering the said ores capable of treatment by ordinary processes with
the object of extracting gold, silver, copper, zinc, nickel, lead &c.
In order to avoid the considerable loss of precious metals accompanying the
direct roasting of so-called refractory ores for expelling therefrom the arsenic,
antimony and tellurium various processes for disaggregating these ores have
been proposed with the object of separating the different sulphurets by breaking
up the crystalline affinity. These processes are based upon the addition of sul-
phurets or polysulphurets (or of a mixture of alkaline sulphate and carbon form-
ing the sulphuret during the course of the disaggregation itself) or of other salts
with the object of breaking up the crystalline form of the ore while utilizing
the faculty of combination of one of the components sulphurets with the added
sulphurets or other added salts.
The process constituting this invention admits of disaggregation of the ore being
obtained by transformation of its crystalline sulphurets into amorphous sulphurets
without the addition of any salt. The different sulphurets are set free without
any change in their chemical constitution taking place. For this purpose, the
ore in a finely pulverized state is mixed with carbon also reduced to powder and
the mixture is heated in a muffle-furnace to a temperature which may vary from
a dull red to a bright red heat according to the nature of the ore.
The arsenic is set free in the state of orpiment vapour while the antimony
and the tellurium remain in the matter under treatment in the state of sulphurets.
The carbon prevents all contact of air by destroying the small quantity of
oxygen that may enter the furnace and forming carbonic acid, but no chemical
action appears to take place as the carbon remains unchanged.
The product which leaves the furnace after the operation is finished retains
its pulverulent condition, not having become agglomerated, and the ore is no
longer crystalline the crystals having been converted into amorphous particles.
The product resulting from the disaggregation may be directly roasted then
subjected to washing with acids for the purpose of removing therefrom the anti-
mony and tellurium and subsequently treated by ordinary processes for extraction
of the metals which it contains viz. gold. silver, copper, zinc etc.

page_text: As the ore after disaggregation still contains all its sulphur it may be used
in the manufacture of sulphuric acid.
Dated this Seventh day of October 1898
An Improved Process for the Treatment of Sulphurous Ores
containing Arsenic, Antimony, or Tellurium.
I, WILLIAM THOMAS WHITEMAN, of No. 7, Staple Inn, in the County of
Middlesex, Patent Agent, 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:-
This invention consists in a process of treatment of sulphurous ores containing
arsenic, antimony or tellurium, whether for extracting these metals therefrom,
or for rendering the said ores capable of treatment by ordinary processes with
the object of extracting gold, silver, copper, zinc, nickel, lead &c.
In order to avoid the considerable loss of precious metals accompanying the
direct roasting of so-called refractory ores for expelling therefrom the arsenic,
antimony and tellurium various processes for disaggregating these ores have
been proposed with the object of separating the different sulphurets by breaking
up the crystalline affinity. These processes are based upon the addition of sul-
phurets or polysulphurets (or of a mixture of alkaline sulphate and carbon form-
ing the sulphuret during the course of the disaggregation itself) or of other salts
with the object of breaking up the crystalline form of the ore while utilizing
the faculty of combination of one of the components sulphurets with the added
sulphurets or other added salts.
The process constituting this invention admits of disaggregation of the ore being
obtained by transformation of its crystalline sulphurets into amorphous sulphurets
without the addition of any salt. The different sulphurets are set free without
any change in their chemical constitution taking place. For this purpose, the
ore in a finely pulverized state is mixed with carbon also reduced to powder and
the mixture is heated in a muffle-furnace to a temperature which may vary from
a dull red to a bright red heat according to the nature of the ore.
The arsenic is set free in the state of orpiment vapour while the antimony
and the tellurium remain in the matter under treatment in the state of sulphurets.
The carbon prevents all contact of air by destroying the small quantity of
oxygen that may enter the furnace and forming carbonic acid, but no chemical
action appears to take place as the carbon remains unchanged.
The product which leaves the furnace after the operation is finished retains
its pulverulent condition, not having become agglomerated, and the ore is no
longer crystalline the crystals having been converted into amorphous particles.
The product resulting from the disaggregation may be directly roasted then
subjected to washing with acids for the purpose of removing therefrom the anti-
mony and tellurium and subsequently treated by ordinary processes for extraction
of the metals which it contains viz. gold, silver, copper, zinc etc.
As the ore after disaggregation still contains all its sulphur it may be used
in the manufacture of sulphuric acid.
:
By way of example, I will cite two applications which have been made of the
above process;
I-Finely crushed pyrites containing 15% of arsenic has been mixed with
10% of carbon in powder and the mixture has been heated for about one hour in
a muffle furnace at a temperature of about 800° C.

page_text: All the orpiment (trisulphuret of arsenic) has become volatilized and the product
obtained contained only traces of arsenic. By the ordinary processes of roasting
and cyanuration 98% of the gold contained in the ore has been extracted.
II. Finely crushed antimonial pyrites has been mixed with 10% of carbon
in powder. The mixture has been heated for about half an hour at a temperature
of 700 to 800° C. in a muffle furnace, the mass withdrawn from the furnace has
been freed from its antimony by calcination and lixiviation with water acidulated
with chlorhydric acid and the product has yielded the whole amount of gold
contained in the ore.
It is evident that the carbon which I employ might be replaced by other organic
matters capable of yielding carbon by calcination.
Having now particularly described and ascertained the nature of the said
invention as communicated to me by my foreign correspondent and in what
manner the same is to be performed, I declare that what I claim is :-
1. A process of disaggregation of sulphurous ores containing arsenic, antimony
or tellurium, consisting in pulverizing the ore, in mixing the same with carbon
likewise pulverized without addition of any salt and in heating the mixture in
a muffle furnace, substantially as hereinbefore described and for the purpose
specified.
2. The herein before described process for the treatment of sulphurous ores
containing arsenic, antimony, or tellurium, consisting in pulverizing the ore,
mixing the same with carbon likewise pulverized and heating the mixture to
expel the arsenic, then calcining the ore, and afterwards extracting the antimony
by washing with acid before treating the ore by ordinary processes for extracting
gold, silver or other metals it may contain.
Talth : h JT.... 1000