Year: 1895

page_text: Date of Application, 5th June, 1895-Accepted, 19th Oct., 1895
We, EWALD FISCHER, Engineer, EMIL KLEIN, Merchant, and FRANZ
MAHLSTEDT, Merchant all of Bahnhofstrasse 20 Breslau, in the German Empire,
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 :-
Our invention relates to certain improvements in the extraction of precious metal
from their ores.
In carrying out such extraction according to methods hitherto adopted, difficulty
is experienced in obtaining continuous working, through the necessity of removing
from time to time the substances used as alloys; and as the clearing away of such
substances is usually performed by hand their surreptitious withdrawal is easily
effected. Furthermore it has only been found possible to secure perfect extraction
of the free gold or other metal; a considerable percentage of the contents of
refractory ores under treatment being generally allowed to pass away with the
tailings, for subsequent extraction by means of extended operations which are
necessarily expensive and tedious.
According to our invention the new or improved process of extraction enables
the whole of the precious metals contained in the ore to be obtained without any
break in the working; the transformation of all the alloys being rendered possible
and deposition thereof occurs in the form of flowers-of-mercury instead of in
homogeneous masses.
This result is achieved by adding lead or other suitable metals to the mercury in
the amalgamating trough or vessel, so that there may be a larger quantity say
10-30 per cent. of amalgamating material in the trough than would be the case
were mercury used alone.
The amount of lead to be used would be equal to the required increase in bulk
of amalgamating material. This lead alloy or amalgam forms with the gold a
double alloy, which during the process is converted into mercury flowers.
Although we have found lead to give the best, results for the purpose of our
invention, nevertheless, zinc or other suitable metals may also be employed with
approximately similar results, and providing the crushing of the ore has been
efficiently done, the whole of the precious metals contained therein will be extracted.
We find also that the addition from time to time to the amalgamating material in
the trough or vessel of 2-5 per cent. of a solution of kalium or natrium
permanganate is advantageous to the extraction of the precious metals by this our
improved process of amalgamation.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is :-
1. In processes for the extraction of precious metals by the use of mercury the
addition of lead or other metals to the quantity of mercury usually employed
whereby the total quantity of amalgamating metal, or metals is increased in volume
substantially as hereinbefore described.

page_text: 2. In my improved process for the extraction of precious metals the use of
kalium or natrium permanganate substantially as hereinbefore mentioned.
Dated this 5th day of June 1895.
HUGHES & YOUNG,
23 Coleman Street, London, E.C., Agents for Applicants.