MENT IN THE PROCESS OF WORKING AURIFEROUS AND ARGENTIFEROUS ARSENIDES AND SULPHIDES OF IRON, COPPER OR OTHER SIMILAR SUBSTANCES BY LITHARGE OR LEAD
Year: 1884

page_text: COMPLETE SPECIFICATION.
I, EDWARD PROBERT, of number 306 Leavenworth Street, in the city and
county of San Francisco, and State of California, one of the United States of
America, Capitalist, do hereby declare the nature of my invention for IMPROVE-
MENT IN THE PROCESS OF WORKING AURIFEROUS AND ARGENTIFEROUS
ARSENIDES AND SULPHIDES OF IRON, COPPER OR OTHER SIMILAR SUBSTANCES
BY LITHARGE OR LEAD: and in what manner the same is to be performed, to
be particularly described and ascertained in and by the following statement :-
My invention relates to that method or process of working auriferous and
argentiferous arsenides and sulphides of iron, or copper, or other similar compounds,
in which litharge or lead is introduced into them while in a state of fusion for
the purpose of extracting from them the precious metals.
My invention consists in a new and useful improvement in said process, namely:
stirring the material under treatment by means of an elastic vapor or vapors
generated by the action of the molten mass upon a mineral substance or substances
within the pot or receptacle in which the material is being treated, and without
the aid of any mechanical stirring by hand.
The object of my invention I shall now explain.
Whereas the success of this method of treatment by the introduction of litharge
or lead into the molten mass, depends largely on the thorough and intimate blending
and admixture of the lead or litharge with the arsenides, sulphides, or reguline
metals under treatment, and whereas the stirring by hand is a laborious, and at
best an imperfect means of effecting the object in view, and in some cases an
impossible one, as in that of the arsenides of iron from the corrosive nature of the
substances themselves, which rapidly destroy all implements of iron or steel
introduced into them for the purpose of stirring, I have invented a method or
improvement by which mechanical stirring is rendered altogether unnecessary, and
a much more complete blending or mixing of the materials is effected.
The method of proceeding is as follows:-Iron pots of a conical shape about
thirty inches deep, thirty inches wide at the top, and rounded off at the bottom
spherically to about twelve inches in diameter, each capable of holding fifteen c'wts,
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page_text: more or less, of the substance to be treated, are coated internally with a lining of
refractory material composed (preferably) of decomposed or pulverized lava, pumice,
or other volcanic rock, but when this is not attainable, of silicious sand, with a
certain admixture of finely pulverized limestone or calcareous marl, to which has
been added a sufficiency of clayed-water or milk of lime to work the whole into
a paste.
After laying on this coating of refractory material, intended primarily to protect
the pot from the corrosive action of the substance to be treated, to the thickness
of about three-quarters of an inch, a further portion of a specially prepared
composition, consisting of coarsely crushed limestone, dolomite, siderito, or other
suitable carbonate, mixed with a sufficient quantity of the ordinary composition
with which the pot is lined, to give it consistency, is laid on the bottom of the pot
to the thickness of one inch, more or less.
The pots thus prepared are placed in a suitable oven or chamber, (or a small fire
is made inside each pot) to dry the coating, which howover is not to be baked so
as to expel the last portions of moisture, but only so far as to remove the excess of
water.
When required for use, the pots thus lined and partially dried are placed, in
succession, under the spout of the smelting furnace containing the substance to be
treated, in a state of fusion, which is then tapped into them while at the same
time, or immediately afterwards, a charge of lead or litharge, preferably granulated,
is fed into each pot from a hopper conveniently placed above.
The first effect of the molten substance tapped from the furnace into the pot is
to convert the small amount of moisture contained in the protective lining of the
pot into steam, which rising upwards from the bottom and sides, causes a brisk
ebullition in the molten material.
This however, is insufficient of itself to effect the thorough stirring and blending
of the contents of the pot necessary to ensure a successful result; but no sooner is
this first ebullition, due to the escaping steam, over, than the limestone, dolomite,
or other carbonate, fixed in the bottom of the pot, as well as the calcareous matter
in the whole lining, begins under the intense heat of the molten charge, to undergo
calcination and streams of carbon dioxide are sent off, which rising upwards
through the molten matter, produce the effect of a small geyser, keeping the charge
in a state of ebullition and agitation for a period of time proportionate to the
quantity of mineral carbonate or other source of carbon dioxide, originally used
in preparing the pot, and thus effecting such a complete blending and intimate
admixture of the ingredients as cannot be attained in any other way.
The duration of the ebullition and consequently of the stirring process, may be
regulated to any required number of minutes, from five upwards, or as long as the
molten material continues hot enough to exercise a calcining effect on the lime-
stone, etc, and inasmuch as the carbon dioxide produced comes off in a steady stream
without sudden bursts, as from the vapor of water, there is never any danger to
the workmen from explosions.
After the ebullition is over, the pot with its contents is set aside to cool, when
the lead settles to the bottom carrying down with it the precious metals, and when
solidified, the mass of alloy can be detached from the waste matter and treated by
cupellation in the usual way for the separation of the silver and gold.
It will thus be seen that the stirring is effected partly by steam, (which, however,
can never be made to do the whole work, being too violent in its action and causing
explosion when too much moisture has been left in the composition,) but chiefly
by the carbon dioxide (carbonic-acid, so called) developed during the calcination of
the limestone or other carbonates employed as the source of gas or vapor.
Although I have in this description referred only to the mineral lining of the pot,
and to mineral substances attached to and practically forming a part of the lining,
as generating the elastic vapor or vapors, I do not wish to confine myself strictly
to this method, for in the treatment of a number of substances it would be
practicable to hold down, introduce, or support in some other manner within the

page_text: molten mass, the suitable mineral substance or substances, to effect a similar result
as that which I have described.
I am aware that in the operation of poling, in the working of copper and lead,
a piece of green wood is thrust into the molten mass, and generates steam to
agitate the material, and I am also aware that in the Bessemer steel process, air
is forced, into the material, and in the process of Pattinsonizing lead, steam is
forced in.
But my process differs from that of poling, in that the elastic vapor is generated
by mineral substances, a distinction highly important in many cases, as for example
in the working of arsenide of iron, where wood cannot be used at all; and it
differs from the steel and Pattinsonizing processes, in being generated within the
pot by the direct action of the molten mass upon the mineral substance.
Having now particularly described and ascertained the nature of my eaid
invention, and in what manner the same is to be performed, I declare that what
I claim is,
The process of separating the precious metals from auriferous and argentiferous
arsenides and sulphides of iron, or copper, or other similar compounds, which
consists in introducing litharge or lead into the fused material contained in pots or
vessels lined with some moistened refractory material, and also containing dolomite,
limestone, or other mineral carbonate in the lining, or distinct therefroin, whereby
the charge is stirred by means of the action of the molten mass upon the lining of
and mineral substance in the pot or receptacle in which it is being treated,
substantially as herein described.
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