AN IMPROVEMENT IN THE MANUFACTURE OR PRODUCTION OF SILICIOUS PIG T3 PRO
Year: 1881

page_text: LETTERS PATENT to Andrew Crawford, of Glasgow, in the County of Lanark,
North Britain, General Manager of the Govan Iron Works, of the Firm of
William Dixon (Limited), Iron and Coal Masters, for an Invention of
"AN IMPROVEMENT IN THE MANUFACTURE OR PRODUCTION OF SILICIOUS PIG
T3
PROVISIONAL SPECIFICATION left by the said Andrew Crawford at the
Office of the Commissioners of Patents on the 10th February 1881.
ANDREW CRAWFORD, of Glasgow, in the County of Lanark, North Britain,
General Manager of the Govan Iron Works, of the Firm of William Dixon
(Limited), Iron and Coal Masters. AN IMPROVEMENT IN THE MANUFACTURE
OR PRODUCTION OF SILICIOUS PIG IRON."
$5
This Invention relates to the manufacture or production of a highly silicious pig
iron which, amongst other uses, is specially adapted for conversion into steel in
what is known as the "open-hearth" or Siemens-Martin process.
The object of the Invention is to produce a pig iron containing silicon to an
extent ranging from seven or eight per cent. upwards, a pig iron containing about
twelve per cent. of silicon being found specially advantageous in the hereinbefore
mentioned steel making process, or in equivalent processes.
It is to be understood that the pig iron constituting this Invention is to be used
not only for casting ingots for subsequent conversion into bars, plates, or other
" uses,
," but also that it may be employed for the direct making of steel castings
other than ingots.
"
The Invention consists in mixing with the raw materials constituting the charges
of blast furnaces a proportion of the slags which are produced in the "open-hearth
steel process, or analogous slags otherwise produced. It is a characteristic of such
slags that they contain a very large per centage of silicon, sometimes as much as
50 per cent. or more thereof, the requisite portion of which is imparted to and
taken up by the pig iron produced from the materials charged into the blast
furnace.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Andrew Crawford in the Great Seal Patent Office on the 9th
August 1881.
ANDREW CRAWFORD, of Glasgow, in the County of Lanark, North Britain,
General Manager of the Govan Iron Works, of the Firm of William Dixon
(Limited), Iron and Coal Masters. "AN IMPROVEMENT IN THE MANUFACTURE
OR PRODUCTION OF SILICIOUS PIG IRON."
My said Invention relates to the manufacture or production of a highly silicious
pig iron which, amongst other uses, is specially adapted for conversion into steel in
what is known as the " open hearth " or "Siemens-Martin" process.
The object of my said Invention is to produce a pig iron containing silicon to an
extent ranging from 7 or 8 per cent. upwards. A pig iron containing about 12 per
cent. of silicon is found specially advantageous in the hereinbefore mentioned steel
making process, or in equivalent processes of producing liquified steel for making
steel castings:
It is to be understood that the pig iron constituting this Invention is to be used
not only for casting ingots for subsequent conversion into bars, plates, or other
uses, but also that it may be employed for the direct making of steel castings other
than ingots.
My said Invention consists in mixing with the raw materials constituting the
charges of blast furnaces a proportion of the slags which are produced in the "open
hearth" steel process, in the Bessemer steel process, or analogous slags otherwise
produced. It is a characteristic of such slags that they contain a very large per-
centage of silica, sometimes as much as 50 per cent. or more thereof, and that the
phosphorus and sulphur are low in such slags. The requisite portion of silicon is
imparted from the silica and taken up by the pig iron produced from the materials
charged into the blast furnace. In smelting these slags with hematite or Spanish
red iron ores about 27 parts by weight of slag is used to 100 parts of such iron
ores, but this proportion will vary according to the richness of the slags in silica,
and of the ores in iron.
Having now described and particularly ascertained the nature of my said
Invention, and the system, mode, or manner in or under which the same is or
may be used or carried into effect, I would observe in conclusion that what I
consider to be novel and original, and. therefore claim as the Invention secured
to me by the herein before in part recited Letters Patent is,--
The production of a highly silicious pig iron, that is to say, a pig iron containing
from 7 to 8 per cent. and upwards of silicon, by smelting with the iron producing
materials either "
open hearth"
steel slags, "Bessemer" slags, or analogous slags
sufficiently high in silica and low in sulphur and phosphorus essentially, as herein-
before described.
In witness whereof, I, the said Andrew Crawford, have hereunto set my
hand and seal, this Fourth day of August, in the year of our Lord One
thousand eight hundred and eighty one.