An Improved Process for the Chemical Disaggregation of Pyrites of Complex Composition, with a view to Rapid Extraction of the Metals contained therein, such as Gold, Silver, Arsenic, Antimony, and Tellurium.
Year: 1894

page_text: Date of Application, 4th June, 1894
Complete Specification Left, 3rd Apr., 1895-Accepted, 4th Sept., 1895
PROVISIONAL SPECIFICATION.
An Improved Process for the Chemical Disaggregation of Pyrites of
Complex Composition, with a view to Rapid Extraction of the
Metals contained therein, such as Gold, Silver, Arsenic, Antimony,
and Tellurium.
1 MICHEL BODY of 8 Rue des Dominicains Liége in the Kingdom of Belgium
Engineer do hereby declare the nature of this invention to be as follows:-
The object of this operation is to break up the crystallographic combination of
pyrites of complex composition and to separate chemically the sulphides of the
metals which they contain in order to facilitate the extraction of the said metals.
Contrarily to what has heretofore been the practice, instead of eliminating the
sulphur from the pyrites for the purpose of extracting the metals therefrom, we
This addition brings
begin our process by adding an excess of sulphur to the same.
about a change of sulphuration and if at the same a fixed base be introduced into
the mixture in the form of either a carbonate, a hydrate, a sulphate or even a
nitrate of soda, the alkaline sulphides produced acting as solvents upon certain
sulphides such as sulphide of arsenic, of antimony of gold and of tellurium admit of
separation thereof by mere decantation or lixiviation. This is what takes place in
particular with the sulphides of the arsenic group.
These reactions cannot be obtained in a suitable manner without the addition of a
third reducing agent and for this purpose a small quantity of carbon is necessary.
These additions to arsenical antimonious or tellurious pyrites when they are
subjected to a temperature not exceeding cherry red give rise to the formation of an
alkaline sulphide which enters into combination with a part of the iron of the pyrites
and forms a soluble alkaline sulphide with which are associated sulphide of gold, of
arsenic of antimony and of tellurium; and if the mass resulting from these reactions
is thrown into water it is separated into two parts: the first being a magnetic
sediment or sulphide of iron reduced to its simplest state (protosulphide) and the
second being a greenish black solution of sulphide of iron and of alkaline sulphide
holding in solution sulphides of arsenic, antimony, gold, silver and tellurium.
If the said solution be separated from the said magnetic sediment by decantation
and be subsequently exposed to the action of air or if in order to act more rapidly,
air and steam, carbonic acid or a strong acid such as hydrochloric or sulphuric acid
be added thereto without entirely destroying the alkalinity of the said greenish black
solution it will separate into two very distinct strata the upper one consisting of a
clear solution containing the whole of the arsenic and of the antimony and the
lower one containing mono sulphide of iron and the other sulphides held in
suspension, especially those of gold and iron. Such are the reactions upon which
is based the disaggregating process which frees the sulphides of gold and silver
from their combination with the sulphides of arsenic, of antimony and of tellurium
and admits of their extraction without the loss attendant on the use of ordinary
processes.
The practical working of these reactions is of the simplest nature and is effected
by means of the arrangements and plant hereinafter described.
The pyrites carefully freed from their gangue by mechanical dressing are crushed
by means of a ball mill with the addition of sulphate of soda, carbon or similar
matters in proportions determined by proper calculation; they are then placed

page_text: upon the sole of a muffle furnace where they are subjected to a cherry or bright red
temperature for half an hour only. When it is found that the crystallized pyrites
have been converted into a black paste (by the aid of a little water and a test
sample) so that no trace of the crystallization of the pyrites can be perceived the
mass is promptly withdrawn from the muffle furnace and is thrown into suitable
stirring vessels containing a certain quantity of water. Here, after resting, the
separation of the magnetic sediment from the solution which is rich in gold and
silver takes place. By decantation the said solution is thoroughly separated from
the magnetic sediment and is then placed in vats where the separation of the matters
held in solution is effected. The said vats are of circular or square shape and are
lined with lead. By the aid of steam and a "Koerting" apparatus air or the
gases issuing from the furnace are introduced therein, and the separation takes
place. The clear liquid above the monosulphide containing precipitate is then
decanted; after a further rest the said liquid is placed in labyrinthic arsenic
troughs, where the precipitation of the arsenic in the state of orpiment takes place.
This is produced by combined action of the "Koerting" apparatus or of an
exhauster with the aid of the sulphurous acid proceeding from the furnace until
the hyposulphites formed return to the state of sulphates. The deposit which is
rich in gold and silver is transferred to a filter press for concentration, and is then
roasted and subjected to plumbic fusion for the purpose of obtaining the gold
and silver by cupellation. The product of the fusion is concentrated gold yielding
material.
As to the magnetic sediment, the little gold which it may still contain is
obtained by MacArthur's process after oxidation by air, or after roasting, by the
ordinary chlorine process. All the products added to the matters treated during
the operations hereinbefore described with the exception of the carbon may be
readily regenerated and may be used for subsequent operations.
Dated this 4th day of June 1901
W. T. WHITEMAN,
Agent for the Applicant.
An Improved Process for the Chemical Disaggregation of Pyrites of
Complex Composition, with a view to Rapid Extraction of the
Metals contained therein, such as Gold, Silver, Arsenic, Antimony,
and Tellurium.
I MICHEL BODY of 30 Rue de l'Equateur Brussels in the Kingdom of Belgium
(late of 8 Rue des Dominicains Liége in the Kingdom of Belgium) Engineer 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 :-
The object of this operation is to break the crystallographic combination of
pyrites of complex composition and to separate chemically the sulphides of the
..metals which they contain in order to facilitate the extraction thereof.
: Contrarily to what is the practice in the generality of methods of treatment of
pyrites instead of eliminating the sulphur therefrom with the view of extracting
the metals they contain take care to retain it in a reducing medium aud in certain
cases I even add an excess of sulphur. The result of this is a change of
.sulphuration and if at the same time a fixed base be introduced into the mass either
in the form of an oxide a nitrate, a carbonate or a hydrate, and especially a sulphate,
the alkaline sulphides produced acting as solvents upon certain sulphides, such as
the sulphides of arsenic, of antimony, of gold, of silver and of tellurium, admit of
their separation by mere lixiviation and decantation or filtration.

page_text: These reactions cannot be obtained in a convenient manner without addition of.
a reducing agent and for this purpose a small quantity of carbon is necessary.
The whole of these additions to arsenical, antimonious or tellurious pyrites,
when they are subjected to a temperature not exceeding cherry red, give rise to
the formation of an alkaline sulphide which will enter into combination with a
portion of the iron of the pyrites and form a soluble alkaline sulphide of iron with
which will be associated sulphides of gold, of silver, of arsenic, of antimony, and of
tellurium and if the mass resulting from these reactions be thrown into water, it
will separate into two parts; one being a sediment in great part magnetic and the
other being a greenish black muddy solution of mono-sulphide of iron and of
alkaline sulphide holding in solution sulphides of gold, silver, arsenic, antimony, and
tellurium.
If the said solution be separated from the said magnetic sediment by decantation
and be afterwards exposed to the air, or if, in order to act more rapidly, air and
steam, or an acid be passed into the said greenish black solution without com-
pletely destroying its alkalinity, it will separate into two very distinct strata; the
upper one being a clear solution containing the whole of the arsenic and a portion
of the antimony in the form of a double sulphide having an alkaline base and the
lower one being a black sediment consisting of mono-sulphide of iron and the other
metallic sulphides held in suspension.
Such are the reactions upon which is based the process of treatment of
sulphurous ores which frees the metallic sulphides from their combination with the
sulphides of arsenic, of antimony, and of tellurium and admits of their extraction in
ordinary ways.
From these reactions results a classing of the complex sulphides constituting
the ore, in the amorphous state, in conjunction with ready elimination of those
products which are the most antagonistic to thorough subsequent extraction of the
precious metals (gold, silver, platinum); besides a method of concentration of
those metals in sulphide of iron which is most easily reducible by kuown industrial
means; as a consequence a possibility is thus obtained of treating the most
refractory and poorest auriferous ores and obtaining a maximum yield therefrom.
The mode of operation by which I produce the said reactions industrially on the
commonest and most refractory ores such for example as arsenical antimonial
auriferous and argentiferous pyrites freed from their gangue, known as sulphuret,
and prepared by stamping, pounding or trituration with or without amalgamation,
consists in adding about ten per cent. of basic salt of potassium, sodium or calcium.
or similar matters and about five per cent. of sulphur and carbon or similar matters
relatively to the mass of the ore; and afterwards in subjecting these matters to
pounding and sifting which brings them to a state of fine division.
The addition of sulphur is not absolutely essential in the treatment of certain
ores.
The product intimately mixed is introduced into a muffle furnace having
condensation chambers, if it be desired to collect as a bye product the small
quantity of arsenic which may distil in the form of orpiment, or into an open
5 hearth furnace if it be desired to obtain it in the form of arsenious acid.
The latter furuace may be used where antimony is present, without arsenic.
At the end of a certain time which depends on the height of the charge on the
hearth and on the intensity of the fire, the product when tested will show all the
characteristics of disaggregation proof of which state is furnished by the conversion
of the crystallized pyrites into a black paste in which nothing can be seen of
crystallization of the pyrites. The said product is then withdrawn and scraped
into a sheet metal duct or trough leading from within the furnace, opposite the
doors, directly into fixed tanks provided with agitators or into rotary vats partly
filled with water.
After a sufficiently prolonged agitation the mass is left at rest when it will
separate into two portions namely a sediment in great part magnetic and an upper
body of fluid containing the rich muds. This fluid is decanted into a second

page_text: tank placed at a lower level, and then subjected to the action of a powerful blast
of air charged with sulphurous acid (which may be obtained from the furnaces)
until the flakes of orpiment which after a certain time appear do not rapidly
disappear or do not disappear at all whereby a neutral condition of the mass is
indicated.
From this operation a new classing of the matter under treatment results. On
resting a black mud is deposited above which a clear liquid remains. This operation,
carefully performed, leaves in the black mud the whole of the gold and silver
contained in the pyrites within a few grammes while the supernatant liquid contains
all the dissolved arsenic.
The muds when passed through a filter press and dried and calcined, are subjected
to plumbic fusion in a suitable furnace and the working lead is submitted to
cupellation.
The clear decanted liquids and those from the filter presses when subjected to
the action of the gases from the disintegrating and caleining furnaces yield all the
arsenic which they contain in the state of orpiment.
If the ore contain antimony it passes into the arsenical liquid to be there
precipitated by lime and submitted to plumbic fusion when it separates from the
lead if the charge contain iron.
The magnetic sediment withdrawn from the disintegration tanks although
retaining but a slight quantity of the gold originally contained in the ore,
constitutes when thus treated, a concentrated mass which may contain a quantity
of gold the extraction of which, owing to the disaggregation, may be very readily
effected by the usual means of cyanuration or even amalgamation the yield being
very considerable.
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 I claim
First. The conversion of the crystalline natural metallic sulphides hereinbefore
referred to as pyrites of complex composition into amorphous sulphides by treating
the said crystalline sulphides in a furnace from which air is excluded with addition
of a base and of carbon and if necessary of sulphur with the object of effecting
the combination of these sulphides with an alkaline sulphide for eliminating the
arsenic antimony and tellurium by dissolution and facilitating the extraction of the
other metals which are contained in the said natural metallic sulphides the ensuing
operations being :-
-
A. The elimination and obtainment of the arsenic and of the antimony in the
form of sulphides which is rendered possible by the solubility of the said
sulphides in the basic sulphides and by their subsequent insolubility in the
presence of oxidizing agents.
B. The concentration of the other metals in muds and sediments resulting
from the action of the aforesaid oxidizing agents upon the matters under
treatment.
Secondly. The methods of hastening the elimination of the arsenic and antimony
contained in the solutions resulting from the disaggregation of the pyrites, which
consist in blowing into the said solutions air and steam or an acid, without
completely destroying the alkalinity or in restoring the solution to the basic state
by addition of lime and allowing it to rest until it separates into a black mud or
deposit and a clear supernatant liquid.
Dated the Second day of April 1805
W. T. WHITEMAN,
Agent for the Applicant.