Improvements in the Preparation of Basic Slag for Fertilizing Purposes.
Year: 1895

page_text: Date of Application, 25th Mar., 1895
Complete Specification Left, 14th D-c., 1895-Accepted, 25th Jan., 1896
PROVISIONAL SPECIFICATION.
Improvements in the Preparation of Basic Slag for Fertilizing
Purposes.
WILLIAM HUTCHINSON of "The Ferns" Pennfields Wolverhampton. Manager
of Steel Works and ALFRED HICKMAN Knight M.P. of Wightwick Wolverhampton
Ironmaster do hereby declare the nature of this invention to be as follows:-
In the manufacture of ingot iron & steel by the basic Bessemer & basic Siemens
processes there is produced a slag which, after being ground to a fine powder is
used as a manure. The value of this slag is largely dependent on its content of
phosphoric acid and of the solubility of this phosphoric acid. The phosphoric acid
in basic slag as usually produced is soluble in a citrate solution to the extent
of 40% to 80%. Our invention has for its object the increasing of the solubility of
the phosphoric acid & this we accomplish by mixing with the basic slag while in a
molten condition a quantity of molten blast furnace or cupola slag. The relative
quantities of each kind of slag to be used vary according to the percentage of
phosphoric acid required in the mixture. We have found equal parts of each give
good results & have also got good results from a mixture of two parts of blast furnace
slag & one part of basic slag. In carrying out our invention we take a ladle or
other suitable vessel to the blast furnace or cupola where the slag from such
furnace or cupola in suitable quantity is poured into it. We then take the ladle
to the basic Bessemer converter or Siemens furnace where the molten basic slag is
poured into & mixed with the blast furnace or cupola slag. The basic slag may
first be put into the ladle and the blast furnace or cupola slag added to it
afterwards but we prefer to put the basic slag, in last.
The whole mixture is then poured from the ladle & cooled preparatory to its
being ground. We have found that the citrate solubility is increased to over
99% by the above treatment.
Dated this Twentieth day of March 189
WILLIAM HUTCHINSON.
ALFRED HICKMAN..
Improvements in the Preparation of Basic Slag for Fertilizing
Purposes.
We WILLIAM HUTCHINSON, of "The Ferns," Pennfields, Wolverhampton, in
the County of Stafford, Manager of Steel Works, and Sir ALFRED HICKMAN, Kt.,
Ironmaster and Chairman of The Staffordshire Steel and Ingot Iron Company
Limited, of Bilston in the County of Stafford, 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 :-
Our invention consists of the improved method hereinafter described of treating
the basic slag obtained in the manufacture of iron and steel by the basic Bessemer
and basic Siemens processes and other like processes for the purpose of rendering
the said slag more efficient when used as a manure.

page_text: In the manufacture of ingot iron and steel by the basic Bessemer and the basic
Siemens processes and other like processes there is produced a slag rich in
phosphoric acid. The said slag ground to a fine powder is largely used as a manure.
The value of the said slag as a manure is dependent upon the proportion of soluble
phosphates contained in it. The phosphates contained in basic slag are to a greater
or less extent insoluble in water their degree of solubility depending on the nature
of the pig iron from which they are derived.
The object of the said invention is to increase the solubility of the phosphates in
basic slag and this we effect by mixing with the said slag, while in a molten state,
molten slag from a blast or iron smelting furnace or from a cupola in which iron is
remelted.
In carrying our invention into effect we take a ladle or other vessel to a blast
furnace or a cupola in action into which ladle or vessel the sing from the blast
furnace or cupola is poured. We transfer the ladle or vessel containing the fused
blast furnace or cupola slag to the Bessemer converter or Siemens furnace or other
like furnace where ingot iron or steel is being manufactured. The basic slag from
the said converter or furnace is poured into and mixed with the blast furnace or
cupola slag in the said ladle or vessel. The mixture of the two slags is made
sufficiently intimate by the pouring of the molten basic slag into the molten blast
furnace or cupola slag but the mixture of the two molten slags may be promoted
by stirring the mixture with an iron rod or other mechanical contrivance.
We give below an analysis of an average blast furnace slag and also an analysis
of an average cupola slag as used by us.
The two kinds of slag may be mixed in equal proportions but where the basic
slag is known to be very rich in phosphoric acid, the proportion of blast furnace or
cupola slag may be reduced to one part by volume of blast furnace or cupola slag
to two parts by volume of basic slag. The basic slag thus treated when cold is
ground and used as a manure in the ordinary way.
By the said invention the whole or practically the whole of the phosphates
contained in the basic slag is rendered soluble and is utilized when the slag is used
as a manure; that is to say, the compound slag formed by the mixture of slags
described is much more, soluble than the basic slag aloue. By solubility is not
meant direct solubility in water as when a lump of the slag is plunged into water
contained, say, in a beaker or other vessel. But what is meant is solubility under
the circumstances in which the slag is used, that is, as a manure. In other words
the compound slag when used as a manure is more rapidly and more effectually
disintegrated than basic slag alone by the moisture of the soil and the action of
the atmosphere and the phosphoric acid contained in the compound slag more
immediately dissolved, and absorbed by the growing plant than the phosphoric
acid of the basic slag without the treatment constituting our invention.
The blast furnace and cupola slags used by us are acid, that is, contain silica in
large proportion. By the analysis of cupola and blast furnace slags hereinbefore

page_text: given it will be seen that the former contains more than 40 per cent. of silica and
the latter more than 34 per cent. These two kinds of slag are always available in
a molten state and by their addition to the molten basic slag the product, which
may be allowed immediately to cool, is found to possess the solubility before
referred to. The cupola and blast furnace slags employed by us have been and
still are to a large extent waste products, and although we prefer to take them
direct from the cupola or blast furnace in a molten state, yet we may take the
waste solid slags and by remelting them use them in our process.
Having now particularly described and ascertained the nature of our invention
and in what manner the same is to be performed we declare that we claim
as our invention of " Improvements in the preparation of basic slag for fertilizing
purposes
"
Treating the basic slag produced in the manufacture of iron and steel by the
Bessemer, Siemens or other basic process, with the slag from a blast or iron
smelting furnace or cupola (which smelting furnace or cupola slags are acid, that
is, contain a large proportion of silica) by mixing the said basic slag and smelting
furnace or cupola slag while in a molten or re-melted state for the purpose and
substantially as hereinbefore described.
Dated the Thirteenth day of December 1895.
W. T. WHITEMAN,
Agent for the Applicants.