from Phosphide of Iron or "Ferro Phosphor."
Year: 1885

page_text: from Phosphide of Iron or "Ferro Phosphor."
I, WILLIAM PHILLIPS THOMPSON Fel. Inst. P.A. of the Agency for Foreign
Patent Solicitors 6, Lord Street Liverpool, in the County of Lancaster and
323 High Holborn in the County of Middlesex, Civil Engineer do hereby declare
the nature of the said invention for "IMPROVEMENTS IN THE EXTRACTION OF
COMPOUNDS OF PHOSPHORUS FROM PHOSPHIDE OF IRON OR "FERRO-PHOSPHOR
(a communication from abroad by Luigi Imperatori of Duesseldorf in the Empire
of Germany, Engineer), to be as follows:--
"
The present application for Letters Patent relates to an improved process for
extracting phosphorus from the phosphide of iron produced in the blast furnace
and known to commerce as "ferro phosphor": this material is pig iron; containing
ten to fifteen per cent of phosphorus.
The ferro-phosphor is first ground or crushed, being brittle and not very hard,
and then heated with alkaline sulphate, preferably sulphate of soda in a rotating
furnace at a low red heat. The proportion of alkali should be at least sufficient to
form tribasic phosphate with the whole of the phosphorus present, but in practice
it is advisable to use ten to fifteen per cent. excess of alkaline sulphate. At a dull
red heat the phosphorus oxidises and combines with the alkali, the sulphate is
reduced and sulphide and oxide of iron are produced at the same time.
Instead of sulphate of potash or soda the corresponding sulphite may be used.
As soon as the mixture is fused it is discharged from the furnace, and after
cooling is broken into pieces and lixiviated with water at 30 degrees. The
insoluble residue consists of sulphide and oxide of iron. After concentration the
solution is allowed to crystallize.
The crystals consist of tribasic phosphate of the alkali plus twelve molecules of
water of crystallization, Na³ (PO) + 12 H² O. The crystals are then exposed to
an atmosphere of carbonic acid whereby the tribasic phosphate of soda is converted
into carbonate of soda and so-called neutral (bi-basic) phosphate of soda 2 Na³
(PO) + CO2 + H₂O = 2 Na₂ H (PO) + Na₂ CO³ This mixture is dissolved in

page_text: warm water and re-crystallised. The neutral or bi-basic phosphate of soda
crystallises out first in rhombical prisms with 12 molecules of water (Na₂ H (PO)
+12 H2O) The mother liquor yields crystals of Na₂ CO, + 12 H. O.
The bi-basic phosphate of soda may be further treated as follows.
An aqueous solution of the salt is added to an equivalent proportion of sulphate
of lime Ca SO and the whole constantly stirred. By double decomposition there
is obtained neutral (bi-basic) phosphate of lime, which is insoluble in water and
sulphate of soda which remains in solution. The precipitate is separated from the
solution by means of a filter press and prepared for sale. The solution evaporated
to dryness gives sulphate of soda, available for the decomposition of fresh quantities
of phosphide of iron. An equivalent of sulphate of ammonia may be added to the
solution of neutral phosphate of soda thus: 2 Na³ H PO' + (NH)2 SO
= 2 Na
(NH) H PO' + Na³ SO The phosphate salt containing ammonia is separable
from the sulphate of soda by crystallization. From the residues which consist of
sulphide and oxide of iron the sulphur may be recovered according to well known
methods such as by burning to produce SO³ for use in sulphuric acid making, or
the residues may be mixed and roasted with common salt whereby hydrochloric
acid and sulphate of soda are obtainable.
The sulphuric acid obtained by the first mentioned process may be employed to
produce from the tribasic or bi-basic phosphate of soda, sulphate of soda and
aqueous phosphoric acid solution.
WM P. THOMPSON & Co.,
Filing Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Extraction of Compounds of Phosphorus
from Phosphide of Iron or "Ferro-phosphor."
I, WILLIAM PHILLIPS THOMPSON, Fel. Inst. P.A. of the Agency for Foreign
Patent Solicitors, 6 Lord Street, Liverpool, in the County of Lancaster, and
323 High Holborn, in the County of Middlesex, Civil Engineer, do hereby declare
the nature of this invention (a communication from abroad by Luigi Imperatori
of Dusseldorf in the Empire of Germany, Engineer) and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement:-
Since the introduction of the Thomas Gilchrist process for dephosphorising iron,
some works such as the Hoerder Works produce a pig iron from the blast furnace,
containing 10 to 15 per cent of phosphorus and which comes into the market under
the name of "ferro phosphor.”
2

page_text: The present invention relates to a new and special process for the extraction of
the phosphorus from this material in the form of an alkaline phosphate.
The process is as follows:
The ferro-phosphor is first crushed: this is usually done by a mill which does
not require great power, as the ferro-phosphor is very brittle and scarcely harder
than well burnt coke. The crushed material is then mixed with calcined sulphate
of potash or of soda in such proportions that the alkali of the salt can combine with
the whole of the phosphorus in the iron to form a normal alkaline phosphate. The
method of arriving at this proportion may be illustrated by the following example:
Let the pig iron contain 12-5 per cent of phosphorus and let the quantity
of alkaline sulphate required per 100 kilos of this material equal x, then
85.8 kilos. In practice it is advisable to use
I
12.5
2'
=
=
'
12.5
62
hence
3Na* SO+ 2P 420
10 to 15 per cent excess of alkaline sulphate.
The mixture is placed in an ordinary rotating soda furnace, such as is used in the
Leblanc process, and heated in the same, with continuous agitation to a low red
heat. At this temperature the phosphorus oxidises to phosphoric acid, the alkaline
sulphate is reduced and forms a basic salt with the alkali. Sulphide and oxide of
iron, are produced at the same time.
With a pig iron containing 12.5 per cent phosphorus corresponding to the
formula Fe P there is obtainable
2 Fe P+ 3 Na' SO' = 2 Na³ (PO) + 3 Fe S + 4 Fe O + Fe.
An analagous reduction takes place when alkaline sulphites are used instead of
sulphates; there is namely produced sulphide of iron and a basic phosphate.
The mixture represented by the above equation consists therefore of 1.15 × 86
kilos 99 kilos of sulphate of soda per 100 kilos phosphide of iron there will
therefore be 1.78 kilos of sulphur per kilos of phosphorus.
-
As the combustion of sulphur liberates 3220 units of heat, and that of phosphorus
6006 units there will be liberated per kilo of phosphorus in the mixture 6006
(1.78 x 2220) = 2054 heat units. These are amply sufficient for the fusing of the
mixture.
As soon as the mixture is fused, it is discharged from the furnace, and after
cooling is broken into pieces, and lixiviated with water at 30 degrees. The
insoluble residue consists of sulphide and oxide of iron. After concentration the
solution is allowed to crystallize.
The crystals consist of tribasic phosphate of the alkali plus 12 molecules of water
of crystallization, Na³ (PO) + 12 H³ O The crystals are then exposed to an
atmosphere of carbonic acid whereby the tribasic phosphate of soda is converted
into carbonate of soda and so called neutral (bi-basic) phosphate of soda.
2 Na³ (PO) + CO2 + H₂ O = 2 Na, H (PO) + Na₂ CO³
This mixture is dissolved in warm water and re-crystallized. The neutral or
bibasic phosphate of soda crystallises out first in rhombical prisms with 12
molecules of water (Na, H (PO) + 12 H³ O) The mother liquor yields crystals
of Na, CO, + 12 H₂ O.
The bibasic phosphate of soda may be further treated as follows:
An aqueous solution of the salt is added to an equivalent proportion of sulphate
of lime Ca SO and the whole constantly stirred. By double decomposition there
is obtained neutral (bibasic) phosphate of lime, which is insoluble in water, and
sulphate of soda which remains in solution.
The precipitate is separated from the solution by means of a filter press and
prepared for sale. The solution evaporated to dryness gives sulphate of soda,
available for the decomposition of fresh quantities of phosphide of iron.
equivalent of sulphate of ammonia may be added to the solution of neutral
phosphate of soda thus:
An

page_text: The phosphate salt containing ammonia is separable from the sulphate of soda
by crystallization. From the residues, which consist of sulphide and oxide of iron
the sulphur may be recovered according to well known methods, such as by
burning to produce SO³, for use in sulphuric acid making, or the residues may be
mixed and roasted with common salt, whereby hydrochloric acid and sulphate of
soda are obtainable.
The sulphuric acid obtained by the first mentioned process may be employed to
produce from the tribasic or bibasic phosphate of soda sulphate of soda and aqueous
phosphoric acid solution.
2 Na³ (PO) + 3 H² SO₁ = 2 H³ PO* + 3 Na² SO₁
2 Na³ H (PO¹) + 2 H³ SO₁ = 2 H³ PO' + 2 Na³ SO*
The process may be simplified by running the molten phosphide of iron into the
rotating furnace in which the well calcined sulphate of soda has previously been
placed. In this case the furnace needs no heating. The rotation of the furnace
mixes the ingredients and the phosphorus is oxidised. After a few revolutions of 1
the furnace the reaction is complete.
The mass is then discharged and treated further according to the processes
already described.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed as communicated
to me by my foreign correspondent I declare that what I claim is
«
1. The process for obtaining tribasic alkaline phosphates from phosphide of iron
ог ferro-phosphor" by fusing the same with an alkaline sulphate or sulphite,
substantially as above described.
2. The process for obtaining carbonate of, soda and bibasic phosphate of soda 2
Na H (PO) from tribasic phosphate of soda by treatment with products of
combustion or other sources of carbonic acid, substantially as described.
3. The process for obtaining aqueous phosphoric acid from tribasic or bibasic
phosphate of soda by treatment with sulphuric acid substantially as described.
Dated this 3rd day of December 1885.