IMPROVEMENTS IN OBTAINING TIN FROM ORES
Year: 1853

page_text: LETTERS PATENT to Frederick William Emerson, of the Trereiffe
Chemical Works, Penzance, for the Invention of "IMPROVEMENTS
IN OBTAINING TIN FROM ORES."
Sealed the 27th April 1853, and dated the 8th March 1853
PROVISIONAL SPECIFICATION left by the said Frederick William
Emerson at the Office of the Commissioners of Patents, with his
Petition, on the 8th March 1853.
I, FREDERICK WILLIAM EMERSON, of the Trereiffe Chemical Works,
Penzance, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN OBTAINING TIN FROM ORES" to be as follows:-
This Invention consists in a mode of employing common salt, with
or without nitrate of potash or soda, when treating ores to obtain tin.
For this purpose I take the ores when stamped and washed, and in
some cases calcined, and I mix therewith common salt, or common salt
and nitrate of potash or soda. These matters are placed in a stone
trough or vessel, and sulphuric acid is applied, which, decomposing
the salts, causes some of the impurities to be rendered soluble, and
thus admit of their being washed and separated from the oxide of tin,
which is then to be treated as is well understood.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Frederick William Emerson, in the Great Seal
Patent Office, on the 8th September 1853.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
FREDERICK WILLIAM EMERSON, of the Trereiffe Chemical Works,
Penzance, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighth day of March, in the year
of our Lord One thousand eight hundred and fifty-three, in the six-
teenth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Frederick William Emerson, Her
special licence that I, the said Frederick William Emerson, my exe-
cutors, administrators, and assigns, or such others as I, the said
Frederick William Emerson, my executors, administrators, and assigns,
should at any time agree with, and no others, from time to time and
at all times thereafter during the term therein expressed, should
and lawfully might make, use, exercise, and vend, within the United
Kingdom of Great Britain and Ireland, the Channel Islands, and Isle
of Man, an Invention for "IMPROVEMENTS IN OBTAINING TIN FROM ORES,"
upon the condition (amongst others) that I, the said Frederick William
Emerson, by an instrument in writing under my hand and seal, should
particularly describe and ascertain the nature of the said Invention,
and in what manner the same was to be performed, and cause the same
to be filed in the Great Seal Patent Office within six calendar months
next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Frederick William Emerson, do
hereby declare the nature of the said Invention, and in what manner
the same is to be performed, to be particularly described and ascer-
tained in and by the following statement thereof (that is to say):
My Invention consists in a means of purifying and separating the
ores of tin from other metallic oxides, sulphurets, arseniates, tungstates,
or other compounds, previously to its introduction into the smelting
furnace, by digesting the ore, either with or without the aid of heat, in
a mixture of common salt, sulphuric acid, and nitrate of soda or potash,

page_text: which last is not absolutely necessary to the success of the operation,
though it helps to shorten the time of the process. To effect this, I
first make a correct analysis of a fair sample drawn from the bulk of
ore to be operated upon, in order to ascertain the exact nature and
amount of the impurities. In the event of its being found to contain
any compound of sulphur or arsenic, I first roast or calcine the ore by
any of the ordinary known methods. If otherwise, this process is
unnecessary. In the event of the ore being found to contain any
oxide of tin (the ores of tin mostly occur as a peroxide), it will be neces-
sary, to avoid loss, either first to peroxidize it, or afterwards to precipitate
from solution by the insertion of metallic zinc, or any other convenient
precipitating agent. To peroxidize the oxide of tin, I wet or saturate
the bulk of ore to be operated on with nitric or nitrous. acid, and after
allowing two or three hours to elapse, to permit a full reaction to take
place, I put it into any iron, fire-clay, or other convenient retort, and
distil or evaporate it to dryness, receiving the nitric or nitrous acid
gases into stoneware, or other convenient condensors or receptacles,
to be used over again. I then mix the ore with such a quantity of
common salt as shall yield a sufficient amount of muriatic acid, by
decomposition with sulphuric acid, as will combine with the contained
impurities of metallic oxides, or bring the oxides. of iron and man-
ganese in wolfram, or the lime in tungstate of lime, into a soluble
state. I then put the ore so mixed with salt into a granite, slate,
stoneware, or other convenient cistern or receptacle, not seriously acted
on by acids, (a wooden trough has been found to answer the purpose,)
and pour upon it such a quantity of sulphuric acid, either "brown acid "
or "oil of vitriol," as will effect the decomposition of the salt. I. prefer
to use an excess of sulphuric acid. I then turn into this mixture a jet
of steam, from a steam boiler of sufficient power to keep it at a heat of
about 200° Fahrenheit, stirring it about from time to time with a
wooden rake or shovel, so as to expose a fresh surface to the action
of the re-agents, adding a small quantity, say 6 or 7 lbs. to the
ton of ore, of nitrate of soda or potash, for the purpose of enlivening
and quickening the operation. In the event of contained micaceous

page_text: or magnetic iron ores, it would be advisable to encrease the amount of
nitrate of soda or potash, to assist their oxidation and conversion..
On account of the volatility of the muriatic acid gas liberated from the
salt by the action of the sulphuric acid, I should rather prefer to make
a strong solution of the salt, and add it by degrees to the mixture of
ore and sulphuric acid.
The duration of the process will, of course, vary with the nature of
the contained impurities; but, generally, twenty-four hours will be
found to be sufficient for the conversion of the most refractory. When,
by examination of a sample drawn from the vessel, the conversion or
solution of the contained impurities has been found to be thoroughly
effected, the supernatant liquor is then to be drawn off, and the result-
ing metallic chlorides, sulphates, and nitrates washed out from the
tin ore by solution in water. The tin ore will then be in a fit and
very improved state for the smelting furnace.
In the event of contained copper, it could be recovered from the
supernatant liquor by precipitation on iron, or by means of any other
convenient precipitating agent.
In the event of contained tungstates, they would be decomposed,
and the iron and manganese in wolfram, or the lime in tungstate of
lime, be brought into a soluble state, while the tungstic acid would
remain in a very finely divided or pulverulent form, and could be
removed either by "floshing in the reeve," or washing in the "buddle,"
or any other convenient means of mechanical separation; or other-
wise, if desirable, may be brought into the shape of an alkaline
tungstate, by digestion in solution of carbonate of soda or potash,
caustic soda or potash, or caustic or carbonate of ammonia, or by
fusion with any alkaline substance capable of forming a soluble tung-
state of alkali at a low red heat, insufficient to reduce the ore of tin,
and the resulting alkaline tungstate removed by solution in water.
My Invention is based upon the fact that, at the moment of decom-
position, most chemical substances have the greatest facility of entering
into fresh combinations; and be it distinctly understood that my claim
is for purifying and separating the ores of tin by acting upon the

page_text: contained impurities with a mixture of sulphuric acid and chloride of
sodium (common salt), either with or without the addition of nitrate
of potash or soda, with or without the application of heat by any
known means.
In witness whereof, I, the said Frederick William Emerson, have
hereunto set my hand and seal, this Thirtieth day of August, in
the year of our Lord One thousand eight hundred and fifty-
three.
F. W. EMERSON. (LS.)
Witness, JNO Cooк.