IMPROVEMENTS IN THE AURIFEROUS PYRITES" EXTRACTION OF GOLD
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by James Plaisted, Lord Penzance, at
the Office of the Commissioners of Patents on the 19th December 1882.
JAMES PLAISTED, LORD PENZANCE, of 64 Brook Street, Grosvenor Square in the
County of Middlesex "IMPROVEMENTS IN THE
AURIFEROUS PYRITES"
EXTRACTION OF GOLD FROM
This Invention has for its object the extraction of gold from ores containing
that metal in combination with iron and sulphur-and with or without other
metals.
These ores are well known under the name of auriferous pyrites.
The raw ore is first calcined by the ordinary methods and then smelted with a
suitable flux the nature and quality of the flux varying with the composition of
the ore and being adjusted to it upon well known principles-the operation being
conducted in a cupola or smelting furnace in the ordinary way.
In this way a regulus or matt is obtained which contains the iron and the gold
with or without other metals.
For some ores of auriferous pyrites it may not be necessary to calcine it previous
to smelting and again for some ores of auriferous pyrites it may answer best to use
a hot blast instead of a cold blast in smelting.
The regulus obtained as above is then crushed or ground. It would be fine
enough if ground to the size of pin's heads or thereabouts the exact size or fineness
not being inaterial and there is no objection whatever to its being ground finer.
It is then treated with dilute sulphuric acid in any suitable vessel-the exact
strength of the acid liquid is not essential but it should not be too strong-an acid
liquor of specific gravity 1.200 answers very well-a dilute liquid made by mixing
what is known commercially as oil of vitriol with four times its volume of water is
as good a mixture as any.
The dilute acid may be applied cold but it is preferable and more expeditions to
heat it in contact with the pounded regulus up to boiling point. In either case
the contact of the acid and regulus gives rise to the evolution of sulphuretted
hydrogen gas which from its highly poisonous nature must not be allowed to escape
in any quantity into the air. Provision therefore for the proper disposal of this
gas must be made in connection with the vessel, in which the operation is
conducted.

page_text: Sulphuretted hydrogen gas as is well known may be burnt in the atmosphere as
it issues from a pipe like ordinary household coal gas and one mode of dealing with
it is to convey it away by pipes to a vessel suitable for the purpose in which it
may be so burnt the product which is sulphurous acid gas being carried away into
the chambers used for making sulphuric acid in the ordinary way. There are
other well known methods of utilizing this gas by obtaining the sulphur from it in
a solid form.
The result of the acid treatment above described is to convert the whole or
nearly the whole of the iron present into sulphate of iron which remains dissolved
in the liquid and the insoluble residue will be found to contain the gold together
The sulphate
with some other metals and perhaps some silica if present in the ore.
of iron solution is then drawn off from the insoluble residue and either crystallized
and sold as copperas or converted by well known methods into red oxide of iron
for the making of paint. The insoluble residue is then collected washed and dried.
If other metals than gold or silver are present in any considerable quantity it may
be necessary or at least desirable to separate them from this residue or do so
partially by well known methods before the next step is taken for the extraction of
the gold but in ordinary cases there will be no need to do so.
The next step consists in melting or fusing the above solid residue with metallic
lead or with some leady material capable of yielding metallic lead in a reverberatory
or other suitable furnace or cupola. The resulting lead will be found to contain
the gold and any silver present in the original ore and the precious metals may
then be extracted by cupellation and separated from one another in the ordinary
way.
It is not essential but it expedites the action of the acid if the pounded regulus
is agitated by any appropriate method while in contact with the acid liquor.
In some cases there may be a portion of the regulus upon which the acid liquor
does not act with the usual facility. Such portions should be heated for some time
in contact with the acid and if any portion of it after boiling for an hour or two
remains unacted upon it should be smelted again with a suitable flux and the
regulus obtained from it treated as before.
Although sulphuric acid is named. herein as the reagent which from its being
more generally accessible it may be desirable to use for extracting the iron from the
regulus as aforesaid-other acids or reagents and especially hydrochloric acid might
be used for the same purpose when once the metals in the ore have been brought
into the proper condition by the previous operation of smelting.