IMPROVEMENTS IN THE CONSTRUCTION OF BLAST FURNACES FOR SMELTING ORES
Year: 1861

page_text: LETTERS PATENT to George Holcroft, of the City of Manchester, Con-
sulting Engineer, for the Invention of "IMPROVEMENTS IN THE CONSTRUCTION
OF BLAST FURNACES FOR SMELTING ORES."
Sealed the 25th April 1862, and dated the 1st November 1861.
PROVISIONAL SPECIFICATION left by the said George Holcroft at the
Office of the Commissioners of Patents, with his Petition, on the 1st
November 1861.
I, GEORGE HOLCROFT, of the City of Manchester, Consulting Engineer, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN THE
CONSTRUCTION OF BLAST FURNACES FOR SMELTING ORES," to be as follows:-
In blast furnaces of the present construction the tuyeres for the admission
of air are arranged on the same level, and consequently act only on one
stratum of the ore and fuel in the furnace. Now, my Invention. consists in
the application of additional tuyeres placed on a higher level than the ordinary
tuyeres, for causing currents of air to act on the charges in the furnace before
they descend to the level of the ordinary tuyeres. By the upper or prelimi-
nary blast or blasts, the furnace is kept in better working order, and the ore is
better prepared for being converted into metal by the action of the lower blast;
the production of the furnace is considerably increased, and the quality of the
metal is improved.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said George Holcroft in the Great Seal Patent Office on the 1st
May 1862.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
HOLCROFT, of the City of Manchester, Consulting Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the First day of November, in the year of our
Lord One thousand eight hundred and sixty-one, in the twenty-fifth year
of Her reign, did, for Herself, Her heirs and successors, give and grant
unto me, the said George Holcroft, Her special license that I, the said
George Holcroft, my executors, administrators, and assigns, or such others
as I, the said George Holcroft, 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 THE CONSTRUCTION OF BLAST FURNACES FOR SMELTING
ORES," upon the condition (amongst others) that I, the said George Holcroft,
my executors or administrators, by an instrument in writing under my, or
their, or one of their hands and seals, should particularly describe and ascer-
tain 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 George Holcroft, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the follow-
ing statement (that is to say) :-
In blast furnaces of the present construction the tuyeres for the admission of
air are arranged on the same level, and consequently act only on one stratum
of the ore and fuel in the furnace. Now, my Invention consists in the appli-
cation of additional tuyeres placed on a higher level than the ordinary tuyeres,
for causing currents of air to act on the charges in the furnace before they
descend to the level of the ordinary tuyeres.
And in order that my Invention may be fully understood and readily carried
into effect, I will proceed to describe the accompanying Drawing, reference
being had to the letters marked thereon.

page_text: The Drawing represents in section the lining of a blast furnace of the usual
construction, to which my improvements are applied.
a, a, are the ordinary tuyeres, above which are situated the additional
tuyeres b, b. In blast furnaces of the present construction it is customary to
place three or more pair of tuyeres at suitable distances apart in the circum-
ference of the furnace, and I prefer to place the additional tuyeres in the
centre of the space between the lower ones, but I do not intend to limit myself
to this position; in some cases the additional tuyeres may be placed singly
instead of in pairs. The number and position of the additional tuyeres and
the distance above the usual tuyeres may be varied. I would also observe that
the blast in the upper tuyeres may be of the same pressure as that used in the
ordinary tuyeres, as would be the case in the arrangement shewn, in which the
pipes c for conveying the blast to the two sets of tuyeres are connected by
branches to the main pipe d, or the pressure may be greater or less in the
upper row of tuyeres.
By the upper or preliminary blast or blasts produced by the additional
tuyeres a greater surface of fuel is acted upon, and more carbon is liberated,
which combining with the oxygen in the ore prepares it for melting, and the
furnace is kept in better working order; the production of the furnace is also
considerably increased, and the quality of the metal is improved.
Having thus stated the nature of my Invention, and described the manner
of performing the same, I declare that I claim the application to blast furnaces
of additional tuyeres placed on a higher level than the usual tuyeres.
In witness whereof, I, the said George Holcroft, have hereunto set my
hand and seal, this Thirtieth day of April, in the year of our Lord
One thousand eight hundred and sixty-two.
GEO. HOLCROFT. (L.S.)