IMPROVEMENTS IN THE MANU FACTURE OF ALUMINATE OF SODA AND POTASH
Year: 1862

page_text: LETTERS PATENT to Charles Cochrane, of the Ormesby Iron Works,
Middlesbro'-on-Tees, for the Invention of "IMPROVEMENTS IN THE MANU
FACTURE OF ALUMINATE OF SODA AND POTASH."
Sealed the 31st October 1862, and dated the 27th June 1862.
PROVISIONAL SPECIFICATION left by the said Charles Cochrane" at the
Office of the Commissioners of Patents, with his Petition, on the
27th June 1862.
I, CHARLES COCHRANE, of the Ormesby Iron Works, Middlesbro'-on-Tees,
do hereby declare the nature of the Invention for "IMPROVEMENTS IN THE
MANUFACTURE OF ALUMINATE OF SODA AND POTASH," to be as follows:-
This Invention has for its object improvements in the manufacture of
aluminate of soda and potash. For these purposes slags (obtained from the
"blast furnace" used in the manufacture of iron) are mixed with a salt of
soda or potash, and subjected to a high temperature, but it is desirable that
they should not become fused or rendered fluid by the heat employed. In
order to reduce the slags into a state of powder, they are run into water; or
they may be otherwise reduced into a powder. The powdered slags are then
mixed with carbonate of soda or potash, which are the salts preferred, and the
mixture is subjected to heat in a suitable furnace or oven. "The product is
then removed from the oven or, furnace, and lixiviated in water, and the
caluminate of soda or potash obtained by evaporation.

page_text: I would remark that, in place of using the slags from the blast furnace, an
artificial slag or compound, produced by smelting a mixture of clay and lime
or limestone or chalk may be used in place thereof.
SPECIFICATION. in pursuance of the conditions of the Letters Patent, filed
by the said Charles Cochrane in the Great Seal Patent Office on the
24th December 1862.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
COCHRANE, of Ormesby Iron Works, Middlesbro'-on-Tees, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-seventh day of June, in the year of our
Lord One thousand eight hundred and sixty-two, in the twenty-sixth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Charles Cochrane, Her special licence that I, the said Charles
Cochrane, my executors, administrators, and assigns, or such others. as I,
the said Charles Cochrane, 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 "IM-
PROVEMENTS IN THE MANUFACTURE OF ALUMINATE OF: SODA AND POTASH," upon the
condition (amongst others) that I, the said Charles Cochrane, my executors
or administrators, by an instrument in writing under my, or their, or one
of their hands and seals, 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.
L
**
NOW KNOW YE, that I, the said Charles Cochrane, do hereby declare
the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by, the
following statement thereof, that is to say:-
This Invention has for its object improvements in the manufacture of
aluminate of soda and potash. For these purposes slags (obtained from the
"blast furnace" used in the manufacture of iron) are reduced to a powdery
form by any of the well-known methods, the best being first to run the slag
whilst in a molten state direct from the blast furnace into water; second, to

page_text: dry the wet friable slag thus obtained; and, third, to crush it, when dry,
between a pair of cylinder rollers. The dry crushed slag is now intimately
mixed with a salt of soda or potash, in the proportions of one part of the dried
salt (the carbonate of soda or potash being preferred) to four parts by weight
of slag, containing about 23 per cent. of alumina. These proportions however
may be varied and should vary with the per-centage of alumina in the slag.
The mixture thus obtained is next thrown upon the hearth of an ordinary
reverberatory or other suitable furnace, in quantities varying of course with
the size of the furnace, say, from 4 to 7 cwts. at a charge, and there subjected
to a temperature somewhat above "cherry red" heat, but falling short of
actual fusion of the ingredients in the furnace, which are to be repeatedly
stirred by the workman, so as constantly to expose fresh surfaces to the action
of the heat. The completion of the process is ascertained by removing from
time to time a small quantity of the contents of the furnace and testing it
with acid, using, by preference, hydrochloric acid. When effervescence ceases
on the addition thereof, the materials are drawn from the furnace, and next
subjected to the well-known process of lixiviation, by which the soluble ingre-
dient of the products of the furnace, namely, the aluminate of soda or potash,
is dissolved out; the liquor containing the salt is then decanted into an
evaporating pan, which may be either heated from above or below, and the
aluminate of soda or potash obtained therefrom by evaporation.
I would remark that, in place of using the slags from the blast furnace, an
artificial slag, produced by fusion of a mixture of clay and lime or limestone
or chalk, may be employed, the mixture being made in such proportions that
for every equivalent of silica in the clay two equivalents, or thereabouts, of
lime shall be present in the resulting compound. The mode of treating
this would of course be exactly as already described in the case of slag from
blast furnaces.
In witness whereof, I, the said Charles Cochrane, have hereunto set my
hand and seal, this Twentieth day of December, in the year of our
Lord One thousand eight hundred and sixty-two.
CHARLES COCHRANE. (L.S.)