Improvements in the Treatment of Complex Gold and Silver Bearing Ores and other Substances and the Recovery of Metals therefrom.
Year: 1888

page_text: Date of Application, 6th Oct., 1888
Complete Specification Left, 25th July, 1889-Accepted, 6th Jan., 1890
PROVISIONAL SPECIFICATION.
Improvements in the Treatment of Complex Gold and Silver
Bearing Ores and other Substances and the Recovery of Metals
therefrom.
1 HENRY HUTCHINSON of 90 Cannon Street in the City of London Metallurgical
and Chemical Engineer do hereby declare the nature of this invention to be as
follows:-
:-
This Invention has for its object improvements in the treatment or preparation of
what are known as complex or rebellious gold and silver bearing sulphurets
arsenurets antimonurets and other ores of a like nature (hereinafter referred to as
complex ores) and also of artificial products such as matt or regulus whereby, Firstly,
such ores and products are better adapted for the effectual extraction therefrom of the
gold and silver contained therein by the well known mercury or amalgamation
method without material alteration of the amalgamation plant usually employed,
Secondly, when the complex ores are so treated by the amalgamation method the
mercury and gold and silver amalgam are prevented from being converted into what
is known as the pulverulent form otherwise known amongst those engaged in mining
as sickening or flouring" of the mercury and gold and silver amalgam, which
when they assume this condition are usually lost in the tailings and whether the ores
or other substances to be treated by such amalgamation be in the raw or in the
calcined condition; Thirdly, the ores can be successfully and economically treated
when desired with solvents such as chlorine, bromine, sulphites, hyposulphites and
hypochlorites for the extraction of the gold and silver contained therein and,
Fourthly, metals such as lead, copper, zinc, cobalt, nickel &c. contained in the
complex ores treated, can be recovered as bye products of such treatment.
**
Hitherto it has been found impossible in the treatment of complex gold and silver
bearing ores of the kind bereinbefore mentioned by the ordinary amalgamation
method to extract by such method gold and silver in payable quantities, owing to the
rebellious nature of the associated elements, namely, sulphur, arsenic, antimony
tellurium and compounds thereof with lead, copper, zinc, iron &c., preventing the
mercury from readily combining with the gold and silver, and further when the gold
and silver does combine with the mercury such rebellious elements cause the mercury
to assume the pulverulent form in which it carries part of the gold and silver
into the tailings and thereby becomes lost.
Another cause of the aforesaid flouring of the mercury I find to be due to the
oxidation of the finely pulverised iron which comes from the stamps employed for
pulverizing the ores. This cause of flouring, which has hitherto been overlooked,
even occurs in free milling ores, and the presence of such oxidized iron prevents the
perfect recovery of the gold and silver bearing amalgam.
In carrying my Invention into practice, for the extraction of gold and silver by
amalgamation, and for the more economical preparation of such complex ores when
it is desired to extract the gold and silver therefrom, by chlorination, bromination, or
with the use of Sulphites, hyposulphites or hypochlorites, as well as to recover the
other metals contained in such ores, as bye-products, I proceed as follows:

page_text: Silver 1 dwt. to 100 oz. per ton or more, such complex ore is first pulverized to a
suitable degree of fineness, (say for example, to such a degree as to pass through a
90 mesh sieve,) and is then introduced, it may be by blowing, into a suitable form of
calcining furnace. A calcining furnace that may be advantageously employed, is
described and shewn in the Specification of a former Application for Letters
Patent, filed by me, dated November 28th 1887 No. 16,270.
In such a furnace, the Ore or Ores is or are calcined with or without admixture
therewith of lime, carbonate of lime or limestone, or of magnesia, or of a mixture
of magnesia and lime or carbonates thereof, or of a mixture of the said substances
and common salt, the proportions of the substances employed being such, (say
15 per cent. in the example taken,) that they combine with the whole or with a part
of the Sulphur present in the ore. The proportion of substance added to the ore
may however vary within wide limits, say from 5 to 50 per cent., according to the
nature of the Ore operated upon.
When calcining such complex Ores as aforesaid, according to this Invention, I
avoid calcining them to what is known to the metallurgist as the "sweet or dead"
condition, that is to say: I do not decompose the Sulphates" formed during
calcination, (and which decomposition usually forms the most costly part of ordinary.
calcination operations) by heat within the furnace, but endeavour to generate as large
a quantity of sulphate or sulphates as possible. The sulphates so produced and which
in the example 'taken will be sulphates of lead, copper, zinc and iron, or it may be
other sulphates according to the nature of the ore operated upon, or if common salt
has been used in the calcination process the chlorides of such metals, are then
removed from the calcined ores in order to prevent such sulphates or chlorides
injuriously acting, as hereinbefore described, upon the mercury and silver amalgam
that is subsequently formed during amalgamation of the ores. I thereby prevent loss
of mercury and gold and silver bearing amalgam due to flouring thereof-According
to my Invention I effect 'the removal or neutralization of the sulphates or chlorides as
follows: The calcineil ore is washed by means of hot or cold water and the soluble
sulphates or chlorides of the metals thereby removed therefrom. There is then 'left'a
residue composed of silica, oxide of iron, sulphate (or chloride) of lead and free gold,
the silver being removed in a soluble state during the washing operation. This gold
bearing residue is then treated with either of the following substances, either in
solution or in the solid state; viz., an alkali or a carbonate thereof, an alkaline earth
or carbonate thereof, or with a mixture of such substances, whereby the rebellious
compound of lead sulphate is decomposed and its flouring effect upon the amalgain
subsequently produced prevented. Loss of gold by such flouringis iconsequently

page_text: avoided. Or the aforesaid alkalies or alkaline carbonates or alkaline earths or the
mixtures thereof may be added direct to the calcined complex ores together with the
water used for washing such ores which may be contained in suitable wooden or other
amalgamating vessels; the decomposition and removal of the rebellions sulphates or
chlorides is then effected in one operation after which mercury is added, and the
amalgamation process completed in the usual manner.
By these means I am enabled to obtain a clean amalgam of Gold and avoid the
formation of what is called "Concentrates when amalgamating by ordinary
methods.
I also use the aforesaid alkalies or alkaline carbonates or the alkaline earths or
carbonates of the alkaline earths or mixtures thereof for extracting gold and silver from
artificial products such as Matts, regulus, and other artificial gold and silver bearing
products, in the manner hereinabove described for complex ores, after such products
have been calcined in the manner explained.
By the preparatory calcination of complex ores in a furnace such as that herein-
before mentioned, and the subsequent removal or neutralization of the rebellious
elements and their compounds in the manner herein before described by the use of
the aforesaid alkalies or alkaline carbonates or alkaline earths or their carbonates,
such ores can be more economically treated than heretofore by the well known gold
and silver solvents viz. -chlorine, bromine, sulphites, hyposulphites, hypochlorites &c.
Such solvents have hitherto been subject to considerable loss in the treatment of gold
and silver bearing ores containing other base metals owing to the baser metals
When,
requiring large quantities of the aforesaid solvents for their removal.
however, such complex ores have been treated according to my invention for the
removal of such baser metals no such loss takes place. To successfully apply the
above named solvents to the treatment of such complex ores they are after calcination
washed with hot or cold water or mixed directly with the aforesaid alkalies or
alkaline earths and when the rebellious elements have been neutralized mercury may
be added and amalgamation effected in the usual manner.
When very rich lead ores containing gold and silver in quantity are to be treated
according to my invention I first thoroughly sulphate such ores, which can be readily
effected in the furnace described in my said former specification. I then dissolve the
lead sulphate and silver sulphate so produced in a solution of a hyposulphite of an
alkali or of an alkaline earth-The residue is then treated with the herein before
mentioned alkalies or their carbonates or alkaline earths or their carbonates or with a
mixture of the same, after which mercury is added and the amalgamation effected in
the usual manner.
The Lead, Copper, Zinc, Cobalt, and Nickel are recovered as bye products by the
usual or other suitable methods from the compounds thereof produced in carrying out
my Invention.
1
1
TOOO
HENRY HUTCHINSON.
Per J. B.
COMPLETE SPECIFICATION.
Improvements in the Treatment of Complex Gold and Silver
Bearing Ores and other Substances and the Recovery of Metals
therefrom.
I, HENRY HUTCHINSON, of 90 Cannon Street, in the City of London, Metallurgical
and Chemical 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 :-
This invention has reference to improvements in the treatment or preparation of
what are known as refractory rebellious or complex gold and silver bearing Sulphurets,
Arsenurets, Antimonurets, and other ores of a like nature (hereinafter referred

page_text: to as complex ores) and also of artificial substances or products such as matt and
regulus (hereinafter referred to as artificial products) containing gold and silver.
The objects of my treatment hereinafter described are-
(1) To convert such ores or substances to such a condition that the gold or silver
(or gold and silver) they contain can be extracted more effectually than heretofore
by the well known mercury or amalgamation process without material alteration of
of the amalgamation plant usually employed.
(2) To prevent the mercury and gold or silver amalgam or mercury and gold
and silver amalgam (whether the ores or other gold and silver bearing substances
be treated in the raw or in the calcined state) from being converted into what is
known as the pulverulent. form that is to say to prevent the same
"
"
sickening"
or
flouring as it is called by those engaged in mining, and thus prevent them being
lost in the tailings as frequently happens when they are allowed to
condition referred to.
assume the
(3) To enable the ores to be successfully and economically treated when desired,
with solvents such as chlorine, bromine, sulphites, hyposulphites and hypochlorites
for the extraction of the gold and silver contained therein, and
(4) To enable metals such as lead, copper, zinc, cobalt, nickel, &c. contained in
the complex ores treated to be recovered as bye products of such treatment.
Hitherto it has not been found practicable when treating complex gold and silver
bearing ores of the kind herein before mentioned by the ordinary amalgamation
method, to extract by such method gold and silver in such quantities, as to render
the process commercially remunerative.
(1) Because the rebellious nature of the associated elements, namely, sulphur,
arsenic, antimony, tellurium, and compounds thereof with lead, copper, zinc, iron &c.
has prevented the mercury from readily combining with the gold and silver.
(2) Because when the gold and silver bave combined with the mercury,
rebellious elements have caused the mercury to assume the pulverulent form in
which it has carried part of the gold and silver into the tailings and thereby has
become lost.
the said
(3) Because (as I have discovered) the oxidation of the finely pulverized iron
which comes from the stamps employed for pulverizing the ores, has been a cause of
flouring this cause of flouring which has hitherto been overlooked, occurs even in
free milling ores, and the presence of the oxidized iron prevents the perfect recovery
of the gold and silver bearing amalgam.
I proceed to describe the manner of carrying my invention into practice.
Preparatory to the treatment of complex ores or artificial products such as referred
to for the purpose of extracting the gold or silver (or both) therefrom whether
(1) By amalgamation with mercury; or
I
(2) By solvents such as chlorine, bromine, sulphites hyposulphites or hypochlorites,
prepare the said ores or artificial products as follows
With the said ores or artificial products I mix one or other of the following
substances viz., (a) an alkali; or (b) an alkaline carbonate; or (c) an alkaline earth;
or (d) a carbonate of an alkaline earth; or (e) a mixture of two or more of the
substances mentioned under (a) (b) (c) (d) either of which will be found to have the
effect of neutralizing the injurious effect of the rebellious elements or compounds
present in such ores or products. These alkaline or alkaline earthy substances may
be added, in the liquid or in the solid state, (a) either during the grinding or
pulverising of the ores or products whether the same are to be subsequently calcined
or not; or (b) after calcination of the said ores or artifical products as in the example
hereinafter described.
Or the ores or artificial products may be mixed with an alkaline earth such as lime
or magnesia, or with a carbonate of either or with mixtures of these substances, and
then calcined in a suitable form of calcining furnace. In the latter case the calcined
ores or artificial products need not be washed to remove soluble compounds (produced
by the calcination) before they are treated by amalgamation, or by solvents for the

page_text: extraction of metal therefrom. The alkali or alkaline earths, or compounds thereof,
have the effect of forming compounds with the rebellious elements which may be either
readily removed by washing or which have (a) no injurious action upon the mercury'
used, and the amalgam produced when extracting the gold and silver by amalgama-
tion; or (b) which do not consume any of the re-agents such as chlorine, bromine,
or the other solvents herein before mentioned when employed for extracting the gold
and silver.
I will describe, by way of example, the treatment or preparation of a complex ore
the follow
تلمسمم
This complex ore is first pulverized to a suitable degree of fineness (say for example
to such a degree as to pass through a 90 mesh sieve).
.
ג:
salt.
It is then introduced, it may be by blowing, into a calcining furnace, an advantageous
form of which is described and shown in the specification of Letters Patent granted
to me dated Nov. 26th 1887 No. 16270. In such a furnace the ore is calcined in the
manner set forth in the said former specification with or without common
according as the ore is to be chloridized or not. The sulphur will be caused during
calcination to forin sulphates with the metals such as iron, copper, lead and zinc in the
ore. In calcining such ores or artificial products I according to my invention avoid
calcining them to what is known to the Metallurgist as the " sweet or "dead"
condition that is to say I do not decompose the "sulphates" formed during calcina-
tion by means of heat within the furnace (and which decomposition usually forms the
most costly part of ordinary calcination operations) but I endeavour to generate as
large a quantity of sulphate or sulphates as possible. The sulphates so produced
will in the example taken be sulphates of lead, copper, zinc, silver, and iron, or it
may be other sulphates according to the nature of the ore operated upon. Or if
common salt has been used in the calcination process then the chlorides of such metals
will be produced together with the formation of sulphate of soda. The soluble
sulphates or chlorides (or sulphates and chlorides) are then removed from the calcined
ore or are neutralized in order to prevent such sulphates or chlorides acting injuriously
in the manner herein before described upon the mercury and the amalgam formed in
the amalgamation process.
I thereby prevent the usual loss of mercury and gold or silver or gold and silver
bearing amalgam due to flouring thereof.
I effect the said removal or neutralization as follows:-
The calcined ore or artificial product may be washed by means of hot or cold water
and the soluble sulphates or chlorides of the metals thereby removed. There is then
left a residue composed of silica, oxide of iron, sulphate or chloride of lead, and free
gold. The silver is removed in a soluble state during the washing operation. The
gold bearing residue is then treated with either an alkali or alkaline earth; or
carbonate of either; or with a mixture of such substances, which may be in the liquid
or in the solid state. The rebellious compound of lead sulphate present in the residue

page_text: is thereby decomposed and its flouring effect prevented upon the mercury and the
amalgam subsequently produced when amalgamating; loss of gold: by such flouring
is consequently avoided. Or the aforesaid alkalies, or alkaline earths. or carbonates
thereof, or mixtures of these substances, may be added direct to the calcined complex
ores or artificial products together with the water used for washing such calcinedi.
ores or products. The said ores or products may be contained in suitable wooden or
other amalgamating vessels. The decomposition and removal or neutralization of
the rebellious sulphates or chlorides is then effected in one operation after which
mercury is added and the amalgamation process completed in the usual manner. By
these means I am enabled to obtain a clean amalgam of gold, or of silver, or of gold
and silver, and avoid the formation. of what are called "Concentrates" as when
amalgamating by ordinary methods.
Or I may add an alkaline earth, or earths, or compounds thereof such as lime,
or limestone, or magnesia, or magnesian limestone, with or without common salt, to
the complex ores or artificial products and. calcine. the mixture thus produced, the
proportion of alkaline earthy substances employed being preferably such (say 15%
in the example taken) that they combine with the whole or the greater part of the
sulphur present in the ore.
The proportion of these substances. used may however vary within wide limits say
from 5 to 50% according to. the nature of the ore operated upon.
ores or
By the preparatory treatment of complex ores and artificial products in the
manner herein described by alkalies or alkaline earthy substances such
products can (as hereinbefore mentioned) be more economically treated than hereto-
fore for the extraction of the gold and silver therein by the well known gold and
silver solvents, chlorine, bromine, sulphites, hyposulphites, hypochlorites &c. Such
solvents have bitherto been subject to considerable loss in the treatment of gold and
silver bearing ores and products containing base metals owing to the baser metals
requiring large quantities of the aforesaid solvents for their removal. When however
such complex ores or products have been treated in the manner hereinbefore
described for the removal or neutralization of such baser metals, no such loss takes
place.
When very rich lead ores containing gold and silver in quantity are to be treated
according to my invention, I first thoroughly sulphate such ores which can be most
readily effected in a furnace such as that herein before referred to. I then dissolve
the lead sulphate and silver sulphate so produced in a solution of a hyposulphite of an
alkali or of an alkaline earth.
The residue is then treated with the herein before mentioned alkalies or alkaline
earths, or carbonates thereof hereinbefore mentioned, after which mercury is added
and the amalgamation effected in the usual manner.
The lead, copper, zinc, cobalt, and nickel present in the ores are recovered as bye
products by the usual or other suitable methods from the compounds thereof produced
in carrying out my invention.
Having no particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. Treating rebellious or complex gold and silver bearing ores and products such as
inatt and regulus (hereinabove referred to as artificial products) (whether in the raw
state or in the calcined state) with either,
(a) An alkali; or
(b) An alkaline carbonate; or
(c) An alkaline earth; or
d) A carbonate of an alkaline earth; or
XXXI
10

page_text: as matt and regulus (hereinabove referred to as artificial products) by calcining a
mixture thereof with either,
(a) an alkaline earth such as lime or magnesia; or
(b) an alkaline earthy carbonate, such as lime-stone or magnesian limestone; or
a mixture of the above substances, and with or without admixture of common
salt (Na Cl), preparatory to subjecting the said ores or products to the action
of mercury or of solvents such as herein enumerated, substantially as herein-
above described for the purposes specified.
3. For the purpose of preparing rebellious or complex gold and silver bearing ores,
and products such as matt and regulus (hereinabove referred to as
"artificial
products") for the extraction of the gold and silver therefrom by amalgamation; or
by the use of solvents, the hereinabove described process of treating such ores or
products, which consists in (a) calcining the said ores or products (with or without
admixture therewith of common salt) in such a manner as to produce as large a
quantity of sulphate or sulphates as possible; and (b) then removing or neutralizing
the rebellious elements or compounds by means of either (1) an alkali; or (2) an alkaline
carbonate; or (3) an alkaline earth; or (4) a carbonate of an alkaline earth; or (5)
a mixture of two or more of the above mentioned alkaline substances with or without
previous washing of the calcined ore or product.
11
T
1000
HENRY HUTCHINSON.
W. Lloyd Wise,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.