IMPROVEMENTS IN THE TREATMENT OF ORES CONTAINING SILVER AND COPPER
Year: 1878

page_text: LETTERS PATENT to Herbert John Haddan, of the Firm of Herbert and
Company, Solicitors of Patents, of 67, Strand, in the City of Westminster,
Civil Engineer, for the Invention of "IMPROVEMENTS IN THE TREATMENT OF
ORES CONTAINING SILVER AND COPPER." A communication from abroad by
Joseph de Baxeres de Torres and Alexis Drouin, both of Madrid, in the
Kingdom of Spain.
Sealed the 25th February 1879, and dated the 7th December 1878.
COMPLETE SPECIFICATION filed by the said Herbert John Haddan at the
Office of the Commissioners of Patents on the 7th December 1878.
HERBERT JOHN HADDAN, of the Firm of Herbert and Company, Solicitors of
Patents, of 67, Strand, in the City of Westminster, Civil Engineer.
"IMPROVE-
MENTS IN THE TREATMENT OF ORES CONTAINING SILVER AND COPPER." A. com-
munication from abroad by Joseph de Baxeres de Torres and Alexis Drouin, both
of Madrid, in the Kingdom of Spain.
The improvements are applicable to all minerals or ores containing both silver
and copper, or one only of either of these metals, whatever may be the other bodies
with which they are mingled or in combination.
The improvements also allow of the profitable treatment of complex minerals,
sulphurets, arseniurets, sulpho-arseniurets, or antimoniurets, &c., of silver and
copper, very abundant in certain countries, but generally unproductive on account,
of the want of a simple process by which to effect their economical treatment.
The improvements are based on the property possessed by marine salt (chloride
of sodium) of decomposing sulphurets of silver to form a soluble chloride in a
solution of salt.
Up to the present time it has not been possible to make this property available
for the extraction of silver, except by roasting the mineral with the salt at an
elevated temperature, which generally volatilizes a considerable portion of the
chloride of silver obtained, occasioning also considerable loss.

page_text: .
The improvements consist in treating a pulverized mineral containing silver with
a solution of marine salt acidulated by nitric, hydrochloric, sulphuric, or any other
suitable acid, whereby the transformation of the silver into the state of chloride is
rapidly and completely effected, even when cold, without the necessity of a previous
calcination, the chloride of silver formed remaining in solution, ten to fifteen hours
being sufficient to obtain this result. Also in and by the addition to the ore of a
small quantity of binoxide of manganese, whereby the re-action is accelerated and
the dissolution of the chloride facilitated. The same solution when cold rapidly.
dissolves the whole of the copper contained in an oxidised ore. Should the ore
contain sulphur, arsenic, or antimony, it will be requisite to roast it to a dark red
heat, in any kind of furnace capable of producing a very oxidising atmosphere,
and will accelerate greatly the roasting, while obviating the agglomeration of
the mineral by mixing it with a very small proportion of binoxide of manganese..
The dissolution of the silver and copper in the acidulated saline liquor may be.
effected in any of the known apparatus; it is preferred however to use casks pro-
vided with double bottoms, abundantly perforated, covered with a cloth to serve
as a filter upon which the pulverized ore is placed, and where it is kept in sus-
pension in the acidulated saline liquor by means of a stirrer, to which adequate
movement is given by animal or steam power. The liquor saturated with silver or
copper is precipitated through the filter into the lower part of the cask, from whence
it passes into other casks containing ore not yet subjected to treatment through
conveniently arranged pipes or conductors.
When the acidulated saline liquor contains all the metal capable of solution the
silver is precipitated by copper, and the copper by iron; the precipitated metals
are well washed, dried, and then smelted in an ordinary furnace, leaving a liquor
holding different salts of soda and iron, to which it suffices to add a small quantity
of acid to render it capable of serving afresh for the dissolution of silver and copper.
The gangues are also repeatedly washed in a solution of acidulated salt, and lastly,
with pure water.
In order to hasten this washing and to extract completely the whole of the
silver, hot or else cold solutions may be employed, containing any known solvent
of the chloride of silver, such as ammonia, hyposulphite of soda, &c.
Chloride of sodium is not the only salt capable of producing the chloridation of
silver under the condition specified; all alkaline chlorides and earthy or metallic
alkalines soluble in a solution of acidulated water may be used, and will produce
the like results; marine salt is preferred on account of its being the easiest to be
obtained.
The treatment of complex sulphurous ores containing silver and copper, when the
silver predominates, is commenced by the extraction of that metal after pulverization
of the mineral by means of the acidulated saline liquor, during which operation
the copper is scarcely attacked on account of the presence of the sulphur, whilst the
silver is entirely dissolved, and after the complete washing the residue is calcined
and treated afresh by the same acidulated saline liquor, which when cold dissolves
the copper in a very short time.
When copper is the predominating metal the operation is commenced by volati-
lizing the sulphur, oxidizing the mineral by means of calcination, treating it after-
wards with the saline solution, which effects at the same time the dissolution of
the copper and the chloridation of the silver, recovering the latter partly from the
dissolution by precipitation, and totally by washings in the manner before stated.
The saline solution may be prepared either in special casks or in the re-action
casks, first mixing the marine salt with the ore, and afterwards introducing the
acidulated water; whichever be the mode of operation adopted the result above
stated will be the same. No definite and exact proportions can be given, as the
richer the ore is in metal the less quantity of materials is required, and so the
treatment may vary in nearly every case.
To make the acidulated saline solution, 5 to 25 volumes of salt are used to every
100 volumes of water, and 1 to 15 volumes of acid. This solution is employed.in

page_text: the proportion of 1 to 5 volumes to each volume of ore treated. The quantity of
binoxide of manganese will vary from 1 to 15 per 1000 volumes.
Any of the known solvents of chloride of silver, either hot or cold, may be
employed for the solution of the chloride obtained under the improved treatment
or process. Also slag may be treated as well as ores.
By means of this process copper and silver can be obtained from the ores or slag
thereof, even those of the most complex description, completely and rapidly, and
with almost insignificant loss.
H. J. HADDAN. (L.S.)