AN IMPROVED METHOD OF EXTRACT- ING SILVER FROM ARGENTIFEROUS MINERALS
Year: 1850

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ADOLF
FREDERICK GURLT, of Manchester, in the County of Lancaster, Gentleman,
send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal' Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Tenth day of October,
One thousand eight hundred and fifty, in the fourteenth year of Her reign,
did for Herself, Her heirs and successors, give and grant unto me, the said
Adolf Frederick Gurlt, my exors, admors, and assigns, Her especial licence,
full power, sole privilege and authority, that I, the said Adolf Frederick Gurlt,
my exors, admors, and assigns, or such others as I, the said Adolf Frederick
Gurlt, my exors, adñors, or assigns, should at any time agree with, and no
others, from time to time and at all times during the term of years therein ex-
pressed, should and lawfully might make, use, exercise, and vend, within England,
Wales, and the Town of Berwick-upon-Tweed, and in the Islands of Guernsey,
Jersey, Alderney, Sark, and Man, and also in all Her said Majesty's Colonies
and Plantations abroad, my Invention of "AN IMPROVED METHOD OF EXTRACT-
ING SILVER FROM ARGENTIFEROUS MINERALS;" in which said Letters Patent is
contained a proviso, that I, the said Adolf Frederick Gurlt, shall cause a
particular description of the nature of my said Invention, and in what manner
the same is to be performed, by an instrument in writing under my hand and
seal, to be inrolled in Her Majesty's High Court of Chancery. within six
calendar months next and immediately after the date of the said' in part.

page_text: recited Letters Patent, as in and by the same, reference being thereunto had,
will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Adolf Frederick Gurlt, do hereby declare that the nature of my said In-
vention, and the manner in which the same is to be performed, are par-
ticularly described and ascertained in and by the following statement thereof,
that is to say:-
Before I proceed to describe the particulars of my Invention, I first shall
shortly refer to those methods which are at present generally adopted for the
purpose of extracting silver from argentiferous minerals, that the peculiarities
of my Invention may be more clearly understood; these methods are,―
Firstly, the eliquation process, in which the argentiferous substance is
mixed with lead or any suitable combination of lead; the silver combines
with the lead owing to its great affinity for that metal, and is afterwards
separated from it by the process of cupellation, which is well understood.
Secondly, the European method of amalgamation in which a chloride of
silver is formed by mixing common salt in a reverberatory furnace, with the
calcined ore or regulus, which chloride is then reduced to the metallic state
by means of metallic iron, and dissolved by mercury, thereby forming an
amalgam, which is separated from the ore or regulus by washing processes,
and is then deprived of its mercury by distillation, leaving metallic silver
behind.
.
Thirdly, the American amalgamation process, which consists in mixing
calcined copper ore (magistral) and common salt with the ore from which the
silver is to be extracted, and by the addition of such a quantity of water as to
form a thick pasty mass, in which the chloride of silver thereby formed is
reduced to the metallic state by iron, and is then dissolved by mercury, which
amalgam is treated in the same way as that formed by the European method
of amalgamation.
. Fourthly, a method by which a chloride of silver is obtained in a similar
way in a reverberatory furnace as in the European amalgation process, and
is then dissolved by means of a hot concentrated solution of common salt,
hyposulphite of soda, or any other suitable agent which will dissolve the
chloride of silver, and separated by means of filtration from the insoluble
portions of the inaterial treated; the silver is then precipitated in the metallic
state by means of any suitable metal.
Fifthly, a method by which all the sulphuret of silver contained in a mineral
is converted by calcination into sulphate of silver, which is extracted by hot
water, and, then: precipitated by cementation.

page_text: My improved method consists in subjecting the argentiferous ore or regulus
containing silver, in the state of a sulphuret, directly to the action of a
solution of common salt, or its chemical substitutes, such as the chlorides of
potassium, ammonium, &c., combined with chloride of copper, iron, zinc, or
other suitable metal, by which means the sulphuret of silver is converted into
chloride of silver, and dissolved in its nascent state by this solution, so that it
may be separated by means of filtration from the mineral with which it was
previously combined; any natural chloride of silver (horn silver) contained in
the ore is likewise dissolved. The argentiferous solution is then deprived of
its silver by cementation, and may again be used for extracting silver from
another portion of ore or regulus.
But in order that my method may be more fully understood, I will now
proceed to describe the best. mode I am acquainted with of carrying the same
into effect. I form the solution which I use for my process in the following
way:-One hundred parts of the concentrated solution of the chloride of. the
alkali or earth and ten or fifteen parts of a concentrated solution of the
metallic chloride are well mixed and heated to about 200 degrees of Fahren-
heit previous to its being used. The mineral to be treated may be an ore of
copper, iron, zinc, &c., or a regulus of these metals, and is in every case to be
reduced to a fine powder, so as to facilitate the lixiviation. When I find that
the gangue of the ore consists of a carbonate or oxide of lime, magnesium,
barium, strontium, &c., which exercise an injurious influence on the solution,
by destroying the metallic chlorides and reducing them to hydrates or oxides,
I prefer to remove the injurious matters by means of a smelting process, which
converts them into a slag and the ore into a regulus. Should it not be desi-
rable, however, in other respects to smelt the ore, I wash the same with
diluted sulphuric or muriatic acid previous to subjecting it to the desilverizing
process, whereby, in most cases, the injurious matters are rendered harmless.
I effect the lixiviation by means of revolving casks, such as. are used in
amalgamation works; these casks are charged according to their size with
the mineral to be treated and with the solution, the latter I recommend to be
added in such proportion as to be equal to at least three times the volume of
the mineral. Both mineral and solution should be heated to about 200
degrees of Fahrenheit when put into the casks, unless means are used to leat
the contents thereof. during the process of lixiviation by steam or otherwise.
After some hours working the solution is tapped out and renewed, which
operation must be repeated until all the silver is extracted, the time and the
number of changes of the solution being entirely dependant on the quantity
of the mineral employed and of the silver to be extracted, the average time

page_text: required for a charge of five hundredweight of ore or regulus is about twelve
hours, in which time three changes of solution are made. I finally wash the
minéral with a concentrated solution of common salt or other solvent of
chloride of silver, in order to remove the remaining silver solution, which
otherwise would be lost. The silver is precipitated from the solution in its
metallic state by copper or any other suitable metal. I always prefer that
metal, the chloride of which constitutes the solution, because a cbloride of the
same metal will then be formed equivalent to the silver precipitated, and the
solution may at once be used again for extracting silver from another portion of
ore or regulus; in other words, a regenerative system of working is established,
the silver after precipitation is then washed and refined in the usual way. In
case the ore to bé desilverized contains, with horn silver and sulphuret of
silver, some metallic silver, but not in such quantity as may be advantageously
extracted by mechanical processes, I prefer to smelt the ore, converting
thereby the whole of the silver into sulphuret, which may then be acted on
by the solution, as above described. The choice of the metallic chloride to be
used in the solution depends to a great extent on the component parts of the
ore or regulus; if the mineral to be treated be an ore or régulus of copper I
prefer a solution of the chloride of copper; if of zinc, I then make use of the
chloride of zinc as the agent to convert the sulphuret of silver into chloride;
if it contain much iron or other metal of no value for succeeding smelting
operations, I use the chloride of iron, being the cheapest of those metallic
chlorides. As regards the choice of the chloride of an alkali or earth in the
solution I generally prefer the chloride of sodium (common salt), as being the
more powerful and cheaper agent, but the chlorides of potassium, ammonium,
lime, &c., also answer the purpose.
Having now described the nature of my Invention, and the best method I
am acquainted with of carrying the same into effect, I wish to be understood
that I do not confine myself to the details herein described, nor do I claim
the exclusive and separate use of either the chloride of sodium and its che
mical substitutes, or of the metallic chlorides; but what I claim is the use
of a combined solution of chloride of potassium, sodium, ammonium, &c., and
of chloride of copper, zinc, iron, &c., for the purpose of extracting silver from
argentiferous minerals.
.
In witness whereof, I, the said Adolf Frederick Gurlt, have hereunto
set my hand and seal, this Twenty-seventh day of March, in the
..
year of our Lord One thousand eight hundred and fifty-one.
ADOLF FREDERICK (L.S.) GURLT.

page_text: AND BE IT REMEMBERED, that on the Twenty-seventh day of March,
in the year of our Lord 1851, the aforesaid Adolf Frederick Gurlt came before
our said Lady the Queen in Her Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein contained and specified, in form
above written. And also the Specification aforesaid was stamped according to
the tenor of the Statute made for that purpose.
Enrolled the Ninth day of April, in the year of our Lord One thou-