IMPROVEMENTS IN OBTAINING OR EXTRACTING SILVER FROM ORES AND OTHER BODIES, AND IN APPARATUS FOR THE SAME
Year: 1862

page_text: PROVISIONAL SPECIFICATION left by William Clark at the Office of
the Commissioners of Patents, with his Petition, on the 26th July
1862. A communication from abroad by Messieurs Charles Edouard
Auguste Vattier, Civil Engineer, and Alfred Joseph Gustave Becourt,
Chemist, both of 29, Boulevart St. Martin, Paris.
I, WILLIAM CLARK, of 53, Chancery Lane, in the County of Middlesex,
Engineer and Patent Agent, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN OBTAINING OR EXTRACTING SILVER FROM ORES AND
OTHER BODIES, AND IN APPARATUS FOR THE SAME," to be as follows:-
The argentiferous ores or other bodies are first reduced to a state of chloride.
or other salt of silver soluble in ammonia, the operation being effected either
with or without the addition of heat.
. The ordinary method of treatment in a cold state consists in exposing them
for a greater or less length of time to the action of chloride of sodium or other
metallic salt suitable for extracting argentiferous compounds soluble in
ammonia. When treating the ores in a heated state they are usually roasted
with chloride of sodium, or other substance capable of converting the metal into
chloride or other salt of silver soluble in ammonia. This Invention consists in.
transforming the chloride or other argentiferous compounds obtained by one or
other of the processes above mentioned into metal.
Treatment of chloride or other salts of silver soluble in ammonia.-The

page_text: compounds resulting from the action of chloride of sodium or other salt suitable
for producing salts of silver soluble in ammonia on all bodies containing silver,
in whatever state it may be found, are pulverized, and in this state introduced
into receivers, where they are submitted to the action of ammonia. The
receivers are of various kinds; 1st, they may consist of barrels, hooped with
projecting concave bands of iron for running on inclined planes, furnished with
iron rails; 2ndly, they may be wood or metal barrels mounted on a fixed axis
on which they revolve on their interior or exterior. In the first case each
barrel is placed on a separate and independent axis, and in the other case the
barrels are all carried in any number on a vertical shaft. 3rdly, fixed barrels
may be used, in which the matters are set in motion by agitators in the
interior, which receive motion from a rod passing through a stuffing-box.
This rod communicates with a steam engine or an hydraulic or other motor.
All the apparatus employed are hermetically closed to prevent the escape of
ammoniacal vapours; they are further furnished with cocks and piping
arranged so as to permit of the argentiferous solutions being easily discharged.
When the argentiferous products have been a sufficient time in contact with
the ammonia, the matters in suspension are allowed to remain in the ammo-
niacal liquid until they are completely deposited. Cocks are placed.at different
heights in the barrels, which permit of ascertaining when the clarification is
complete; on this result being attained the lower cock is opened, and the
liquid drawn off into closed vessels furnished with conduct pipes and cocks.
Precipitation of the silver as metal.-The ammoniacal solution of argen-
tiferous compounds after being conducted into vessels where the precipitation
of tho silver metal is to take place, the operation is then effected as follows:-
I introduce into the solution some scraps of iron, zinc, or other metal suitable
for precipitating the silver from the compounds it contains. The liquid is then
stirred, to increase and multiply the surfaces of contact as much as possible,
which is continued until the metal is entirely precipitated. I then ascertain
whether the operation is complete by withdrawing a little of the liquid at
different levels, and then submitting them to suitable experiments. When
the precipitation of the silver is complete, the ammoniacal liquid is again
poured on a fresh portion of the argentiferous compound obtained by the hot
or cold processes first above described. This re-application of ammonia on
fresh quantities of ore presents the double advantage of producing a saving in
the amount of ammonia employed, and also of obtaining other metals in com-
bination with the silver from the ammoniacal solutions after several applications,
which may be afterwards separated therefrom. When the silver is separated

page_text: from the precipitating solution it is washed in water, and then made into
ingots or dust for commercial purposes. The quantity of ammonia employed
depends entirely on the richness of the ores that are treated.
This Invention thus consists in the extraction of silver from the extraneous
matters in which it is found by the processes herein described, which are
distinguished by the substitution of ammonia or other bodies suitable as
solvents of the argentiferous compounds, as described, instead of the mercury
usually employed.