An Improved Method of Producing a Fertilizer Rich in Phosphoric Acid, and a Phosphorous Pig-iron.
Year: 1899

page_text: COMPLETE SPECIFICATION.
An Improved Method of Producing a Fertilizer Rich in Phosphoric
Acid, and a Phosphorous Pig-iron.
I, ALBERT JACOB LEOPOLD of FORSELLES, of the Naphta Produktions-gesellschaft
Gebrüder Nobel, St. Petersburg, in the Empire of Russia, Engineer, do hereby
declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:-
My invention relates to a method of producing from apatite, phosphorite or other
phosphorous minerals or rocks (i.e. minerals or rocks containing chemically combined
phosphorus) a fertilizer which is rich in phosphoric acid and readily soluble, while at
the same time as a secondary product of the process a pig-iron is obtained containing
a high percent. of phosphorus and suitable either for treatment according to the
basic Bessemer or Siemens-Martin process, or for casting, or for other purposes.
The invention consists in smelting in a furnace (blast-furnace, cupola or similar
furnace) apatite, phosphorite or other phosphorous rock together with coal, suitable
fluxes, and iron scrap, whereby on the one hand a slag is obtained rich enough in
phosphoric acid to be particularly well suited for use as a fertilizer, and on the other
hand a pig-iron which has such a high percentage of phosphorus that it is suitable
for the basic Bessemer or Siemens-Martin process in which the phosphorus is
removed.
The mode of carrying out the process does not differ materially from that employed
in an ordinary blast-furnace process for the reduction of iron from its ores; the
difference lies only in the nature of the charge to which, besides the usual
ingredients, is added a large quantity of apatite, phosphorite, or other phosphorous
material, that is to say, an ingredient which has hitherto been always avoided in the
blast-furnace process.
The scrap-iron is introduced in the charge together with coal, phosphorous
material and sufficient of other ingredients (dolomite, lime, quartz) suited to the kind
of rock of said material, to produce the slag wanted. The proportions of course vary
according to the kind of the phosphorous material and must be determined in advance
by sample-smelting or by analyses.
The following proportions are given as examples :-
I
Iron scrap
9 parts,

page_text: Apatite
Chloride of sodium
Lime
Bessemer scrap
V.
Iron scrap
Coke
Apatite
Lime
5 parts,
0.5 parts,
0.5 parts,
3 parts,
5 parts,
5 parts,
4 parts,
1 part.
In its passage through the furnace the rock of the phosphorous material combines
with the flux to form a slag while the phosphoric acid is liberated and combines
partly with the carburetted iron and partly with the base of the slag.
The smelting-products will accordingly be on the one hand a slag rich in
phosphoric acid and suitable as a fertilizer, which slag should preferably be
granulated, and on the other hand a phosphorous pig-iron which can either be used
for foundry work or, as before mentioned, be refined by the basic Bessemer or
Siemens-Martin process, in which case its phosphorus can be recovered in the slag
formed in the latter process.
It may be added that it is already known to smelt in a blast-furnace phosphorous
scrap of pig-iron or wrought-iron in comparatively small quantities together with
iron-ore, but the pig-iron thus produced contains such a small percentage of
phosphorous that it has not been suitable as a foundry iron, nor has it been suited
for refining by means of the basic Bessemer or Siemens-Martin process, nor has the
slag acquired such a percentage of phosphorus as would adapt it for use as a
fertilizer. By the addition of a phosphorous material on the other hand as herein
above described, the advantage is gained that the iron will contain such a high
percentage of phosphorus that it will be particularly well suited for the processes
mentioned and the slag at the same time be an excellent fertilizer.
Furthermore, it is well known to smelt in a furnace iron-ore containing apatite,
together with coal and a flux, but in this case the apatite forms no addition to the
charge but merely constitutes an impurity, and an additional difference between
the said method and the present one lies in the fact that by the latter method
scrap can be utilized and at the same time a valuable slag obtained.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I claim
is:-
An improved method of producing in one process a fertilizer rich in phosphoric
acid, together with a phosphorous pig-iron, consisting in smelting in a blast- or
cupola-furnace a mixture of coal, iron-scrap, fluxes-if required and a sufficient
quantity of phosphorous rock to give to the pig-iron obtained a percentage of
phosphorus suitable for producing a very fluid molten metal for castings, or for
treatinent according to the basic Bessemer or Siemens-Martin process, while the
slag at the same time obtains such a percentage of phosphorus that it will be
suitable as a fertilizer.
D. YOUNG & Co.
11 & 12, Southampton Buildings, London, W.C., Agents for the Applicant.