IMPROVEMENTS IN THE MANUFACTURE OF PHOSPHORETTED IRON
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by Richard Werdermann at the Office of
the Commissioners of Patents on the 7th December 1877. A communication
from abroad by Ludovic Boblique, of Paris, France.
RICHARD WERDERMANN, of Prince's Street, in the County of Surrey, Civil
Engineer. "IMPROVEMENTS IN THE MANUFACTURE OF PHOSPHORETTED IRON." [A
communication from abroad by Ludovic Boblique, of Paris, France.]
This Invention relates to the manufacture of phosphoretted iron of various quali-
ties or degrees of hardness, and is chiefly designed for the production of very hard
metal, which resembles steel. I smelt iron ore together with phosphate of lime or
any other suitable phosphate, and a sufficient quantity of silica to form a fusible
slag. The phosphoric acid is reduced together with the oxide of iron. The pro-
duct is iron, in which the per-centage of phosphorus varies 1°, according to the
quantity and quality of the phosphate employed, and 2°, according to the compo-
sition of the slags. The latter, in fact, are real salts. They are seldom neutral;
sometimes they are basic, but generally they contain silica in excess, and may be
considered as acid salts.
When the bases are in excess a part of the phosphorus passes into the slag
because the silica does not re-act completely on the base of the phosphate; but
when silica is present in excess all the phosphorus passes into the iron and phos-
phoret of iron containing up to 25 per cent. of phosphorus may be produced. It is
therefore easy to produce iron containing a definite per-centage of phosphorus,
either directly from the furnace by mixing ores and phosphates in convenient pro-
portions, or in smelting ordinary pig iron together with phosphoret of iron.
According to the per-centage of phosphorus contained in it the phosphoretted
iron has different qualities. The richest in phosphorus is crystallized in needles;
it is porous, very brittle, and of a blue or yellow tint, like tempered or annealed
steel.
When the per-centage of phosphorus does not exceed 12 per cent. the iron
resembles hard or white cast iron. The structure is still crystalline, but the facets
are very large; the strength is increased, and the metal is very hard. With a per-
centage of phosphorous of less than 4 per cent. the metal has a fine grain com-

page_text: parable to that of steel. But all these raw products contain in addition to phos-
phorus a certain quantity of silica and carbon, and as the metal resembling steel
can only be obtained by combining phosphorus with pure or nearly pure iron the
product must be refined. I therefore smelt the raw phosphoretted iron with fluxes
containing very little or no silica; I use by preference mixtures of alumina, with
lime, magnesia, baryta, strontia, and the like, to which I add some peroxide of iron,
and a convenient quantity of cryolite or fluoride of calcium. Sometimes I also
add some chloride of sodium and carbonate of soda. In short, I use earthy and
ferruginous aluininates, the fusibility of which I increase by mixing them with
fluorides and alkalis free or combined.
The following fluxes I have found to serve very advantageously for the purpose
100
I generally use about 6 lbs. of either of those fluxes for every hundredweight of
iron. The slag can be used again for a second charge, its purifying qualities not
being exhausted by one operation.
The phosphoretted iron is smelted in a reverberatory, or in a puddling furnace, or
in crucibles, or is introduced into them in a liquid state, together with about 6 per
cent. of the refining flux, care being taken to prevent as much as possible oxidation
by contact with air.
After having been for about an hour in contact with the well liquified slag, and
after having been puddled for about twenty minutes, the metal is ready to be poured
into the moulds. The slag remains in the furnace, and is used for a second charge,
but the same quantity of flux is added to it, a similar quantity of slag being
always left in the furnace, and the same quantity of flux being added with every
new charge.
In order to produce iron containing a very small per-centage of phosphorus, the
phosphor pig iron is refined in a suitable furnace, by preference a puddling furnace,
the quantity of peroxide of iron added to the flux being increased. A largo part
of the phosphorus is oxydised and passes as phosphate of iron into the slag. By
puddling the per-centage of phosphorus may be reduced to 0.15, or 010 per cent.,
which gives a metal very suitable for the manufacture of railway rails, axle bearings,
projectiles for ordnance, and the like. As the metal is very sonorous it may also be
advantageously employed for the construction of bells, and as its coercitive force
is at least equal to that of steel it may be used for forming permanent magnets.