AN IMPROVED PROCESS IN SMELTING. ARGENTIFEROUS OBES
Year: 1835

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES.
MICHELL, of Truro, in the County of Cornwall, Gentleman, send greeting.
WHEREAS His most Excellent Majesty King William the Fourth, by.
His Letters Patent under the Great Seal of Great. Britain, bearing date at
Westminster, the Twenty-second day of Juue, in the fifth year of His
reign, did, for Himself, His heirs and successors, give and grant unto me,,
the said James Michell, His especial licence that I, the said James,
Michell, my exors, admiors, and assigns, or such others as I, the said,
James Michell, my exors, aditors, or assign, should at any time agree
with, and no others, from time to time and, at all times during the terni.
of years therein expressed, should, and lawfully might make, use, exercise,
and vend, a certain. Invention of "AN IMPROVED PROCESS IN SMELTING.
ARGENTIFEROUS OBES," within England, Wales, and the Town of Berwick-upon-
Tweed, in which said Letters Patent there is contained a proviso, obliging mc,
the said James Michell, by an instrument in writing under my hand and seal,
particularly to describe and ascertain the nature of my said Invention,
and in what manner the same is to be performed, and to cause the same
to be inrolled in His Majesty's High Court of Chancery within six calendar
months next and immediately after the date of the said. recited Letters
Patent, as in and by the same, reference being thereunto had, will more
fully.and.at large appear.
NOW KNOW YE, that in compliance with the said proviso. I, the said
James. Michell, do hereby declare the nature of my Invention, and the manner

page_text: in which the same is to be performed, are fully described and ascertained in
and by the following description thereof (that is to say):—
My Invention consists in the process herein-after described of submitting
successive charges of agentiferous ores, free or nearly free from sulphur and
arsnick, to be fused with the sulphuret produced by a previous charge of
agentiferous ores, free or nearly free from sulphur and arsnick, in admixture
with sulphur or with iron pyrites, till sufficient silver is concentrated; or where
the agentiferous ores contain sufficient sulphur, then after the first charge of
uncalcined ore has been fully smelted, and the slag removed, the process bere-
after described, of submitting successive charges of argentiferous orcs, free or
nearly free from sulphur and arsnick, to be reduced and concentrated by the
sulphuret obtained by the smelting of the first charge of the furnace.
Having thus stated the nature of my Invention, I will proceed to explain
in the best manner I am acquainted with of performing my said Invention.
The smelter having ascertained the composition of the various parcels of ore to
be smelted, and having ascertained the best mixture which will give the whole
when in a melted state the greatest degree of fusibility, all which is well under-
stood and commonly practised, he calcines the mixture so made, in order to
sublimate the sulphur and arsenic, and to decompose the earthy oxides, (but some
agentiferous ores being free or nearly free from sulphur and arsnick naturally,
it is not absolutely necessary that they should be calcined, although they will
be found better for subsequent fusion if calcined). This process should be
continued till nearly the whole of the arsenic and sulphur are expelled. Theso
remarks relate to argentiferous ores, which before calcining do not contain
sufficient sulphur for the first charge, and to receive subsequent charges of
calcined or other ore, free or nearly free from sulphur and arsnick as herein-
after described. The argentiferous ores, when calcined, are found better for
the after process of fusion if left exposed to the influence of the atmosphere
for a week or more. The smelter proceeds to charge a reverbatory furnace
with a quantity of the calcined or other argentiferous ore, free or nearly free
from sulphur and arsnick (say one ton) together with the usual fluxes, such
as lime, fluor, &c.; those are to be intimately blended with about three hundred-
weight of sulphur, or otherwise with six hundredweight of iron pyrites. This
mixture is to be submitted to an intense heat until the whole is brought into
very perfect fusion, when the silver will subside from the silicates and other
earthy oxides, constituents of the slag, into the sulphuret. The slag thus freed
from the silver is to be skimmed or tapped off very carefully from the surface
of the metallic sulphuret, taking care that as little as possible of the sulphuret
is removed in the process of tapping or skimming. Another charge of calcined

page_text: or other ore, free or pearly free from sulphur and arsnick (about one ton) is to be
put into the furnace with the fused metallic sulphuret produced by the former
charge, and the whole is to be brought to a perfect state of fusion. The con-
centration of the silver contained in the second charge of calcined argentiferous
or or other argentiferous ore nearly free from sulphur will take place, the
slag is again to be removed by skimming or tapping, and this process of
adding charges of calcined argentiferous ore or other argentiferous ores nearly
free from sulphur and arsnick is to be continued without further addition of
sulphur or of iron pyrites after the first charge till the smelter considers there
is a sufficient quantity of silver concentrated, which he will readily ascertain
by testing the slag, and when he ascertains it to contain in assaying it as much
as two to two and a half ounces of silver to the ton; he should stop all further
additions of calcined or other argentiferous ores to the fused sulphuret in the
furnace, as the sulphuret will then be so charged with the silver as to
materially reduce its powers of concentrating more from future charges of
calcined ore, without leaving the slags so rich of silver as to materially lessen
the benefit of adding such additional charge after the slag has been found to
have come off of the richness before mentioned. The charge of sulphuret is
then to be tapped off from the furnace for a future operation with lead, for
which purpose it must be pulverized (if it has not been granulated by tapping
into a pit of water) and calcined, and it will be better for being subjected to
the atmosphere for a week before submitting the calcined sulphuret to further
process, after which the lead may be added and fused with the calcined
sulphuret in another. reverberatory furnace, and the silver refined by cupellation,
as is well understood. It should be remarked that each charge should be stired
when in a state of fusion, and afterwards.remain some time, say from twenty
to thirty minutes, before the slags are skimmed or tapped off, and also that each
successive charge of calcined or other argentiferous. ores should be mixed with
the usual fluxes, and for this purpose it will be found desirable to have a
large
heap of calcined or other ore nearly free from sulphur and arsnick, well mixed
with fluxes, as is well understood. It will only be desirable further to remark,
that in case the first charge of argentiferous ore in an uncalcined state,
containing sufficient sulphur, be used in place of the application of sulphur to
calcined or other agentiferous ore, free or nearly free from sulphur & arsnick
as above described, then to the sulphuret produced by the fusing of the same,
successive charges of calcined or other argentiferous ores, free or nearly
free from sulphur and arsnick, are to added according to the process above
described. I, however, prefer using calcined argentiferous ores with the addi-
tion of sulphur or of iron pyrities, as above as described; but by either means

page_text: of performing the process, considerable saving will take place in the process
of reducing argentiferous ores; and I would have it understood that, although
I have stated three hundredweight of sulphur or six hundredweight of iron
pyrites to one ton of calcined or other argentiferous ore, free or nearly free
from sulphur and arsnick for the first charge of the furnace, I do not confine
myself thereto, but only state such relative proportions as the best I am
acquainted with.
Having thus described the nature of my Invention, and the manner of
performing the same, I would have it understood that what I claim as my
Invention is the process of submitting successive charges of argentiferous ores,
free or nearly free from sulphur, to be fused with the sulphuret produced by
the previous or first charge, whether such sulphuret be the result of applying
sulphur or iron pyrites to calcined or other argentiferous ores, free or nearly
free from sulphur and arsnick, or the result of argentiferous ores containing
sufficient sulphur as above described.
In witness whereof, I, the said James Michell, have hereunto set my
hand and seal, this Fourteenth day of December, in the year of our
Lord One thousand eight hundred and thirty-five.