IMPROVEMENTS IN THE PRODUCTION OF MINERAL PHOSPHATES FROM THE SLAG RESULTING FROM THOMAS'S DEPHOSPHORISING PROCESS IN THE MANUFACTURE OF BESSEMER STEEL, AS ALSO FROM OTHER PRODUCTS AND MINERALS CONTAINING PHOSPHORIC ACID
Year: 1883

page_text: .
PROVISIONAL SPECIFICATION left by Charles Denton Abel at the Office of
the Commissioners of Patents on the 23rd November 1883. Communicated
to him from abroad by Johannes Brandt of N° 131 Konigsgrätzer Strasse,
Berlin in the German Empire, Civil Engineer.
CHARLES DENTON ABEL of N° 28 Southampton Buildings, Chancery Lane in
the County of Middlesex "IMPROVEMENTS IN THE PRODUCTION OF MINERAL
PHOSPHATES FROM THE SLAG RESULTING FROM THOMAS'S DEPHOSPHORISING
PROCESS IN THE MANUFACTURE OF BESSEMER STEEL, AS ALSO FROM OTHER
PRODUCTS AND MINERALS CONTAINING PHOSPHORIC ACID". [communicated to him
from abroad by Johannes Brandt of N° 131 Konigsgrätzer Strasse, Berlin in the
German Empire, Civil Engineer.]
The following improvements in the production of mineral phosphates from the
slag resulting from Thomas's dephosphorising process, and from other products or
minerals, are based on the treatment of phosphate of iron by means of chloride of
calcium at a high temperature, and if necessary, in the presence of air or steam.
Experiments have shown that minerals and products containing phosphoric acid,
but having neither iron nor manganese in the form of metals or sulphides, as for
instance,. phosphate of iron, manganese, aluminium &etc, either pure or in
combination with other substances, such as ferric oxides &c; also, the phosphates or
silicates of alkaline earths, silicates and oxides of iron; and generally phosphoric
acid and iron, manganese, aluminium in the presence or absence of lime, magnesia,
strontia, baryta, silicic acid in any form, can be worked much more simply under..
the treatment of phosphate of iron with chloride of calcium. To the phosphatic
minerals which are suited to this process may also be reckoned many phosphorites,
coprolites, vivianites and bog iron ore. It having been found by experiment that,
for instance, phosphate of iron combined with chloride of calcium, both perfectly.
dry and at about a red heat, give off, in the presence of air, a quantity of chlorine
equivalent to the phosphoric acid while phosphate of lime and oxide of iron free
from phosphorus and insoluble in weak acids remain ; also, that in heating the
same to redness under exclusion of air, sublimed volatile soluble chloride of iron is
formed and lastly that, in the presence-of-superheated steam, the same products
result, but with the substitution of hydrochloric acid in place of chlorine, it'
”מ

page_text: will be sufficient to mix the above named substances with as much chloride of
calcium, or, in the presence of carbonate of lime or magnesia, with as much
hydrochloric acid as is requisite to produce a quantity of chloride of calcium (or
chloride of magnesium or chloride of strontium) at least equivalent to the quantity
of phosphoric acid present. If silicates are present, a corresponding quantity of
hydrochloric acid must be added to decompose them.
The conversion, effected by heating to redness in air or steam, is complete, and
after extraction of the phosphate of lime formed by means of dilute acids, there
remain oxides of iron and manganese free from phosphorus.
The minerals heated to redness with chloride of calcium or any equivalent chlorine
comination, either in air or steam, are effectually decomposed, while, at the same
time, the chlorine of the chloride of calcium is obtained either as chlorine or as
bydrochloric acid or chloride of iron under exclusion of air or steam.
By means of this simple process therefore, a number of substances that occur in
large quantities, and that have hitherto been comparatively valueless, are converted
into valuable products.
The separation of the chlorine from the chlorides of calcium, strontium,
magnesium &c is effected much more rapidly and completely by heating with
oxides of iron, manganese or aluminium than when treating those substances alone,
and consequently this reaction can be effectually used for the cheap production of
hydrochloric acid.
Experiments have furthermore shown that it is of advantage to precipitate the
phosphate of lime obtained in solution as above described, by means of magnesite,
or carbonate or burnt magnesia, in order to enable the hydrochloric acid employed
to be recovered. For this purpose the said products are first lixiviated with a
certain quantity of hydrochloric acid of from two to three per cent strength and
the saturated lye is then precipitated by means of carbonate or caustic magnesia,
the latter entering completely into solution as chloride of magnesium, while the
phosphates of the alkaline earths, together with the small quantities of the yet
soluble iron (which passes almost entirely into the first part of the lye while
the latter portions are almost entirely free) are precipitated. The filtrate of the
precipitate, which can be used directly as manure, is again mixed with as much
free hydrochloric acid (either gaseous or dissolved in water) that the percentage of
acid is again. about from 2 to 3, whereupon the lye is again available for lixiviating
a new quantity of the product.
By repeating these operations, the lye is always newly enriched with chloride of
magnesium, until at length the concentration is so great that it can be evaporated
to dryness without great expenditure of fuel.
The residue after evaporation, consisting of chloride of magnesium and a small
quantity of chloride of calcium, is heated to redness in the presence of steam; the
escaping hydrochloric acid is caught, and the remaining product is mixed with a
sufficient quantity of chloride of magnesium to decompose or neutralise the caustic
lime that may be present.
For decomposing the oxychloride of magnesium also obtained, this addition is
not required.
The magnesia thus obtained can be used again for the precipitation of the
phosphate of lime from the lye. In this way, one and the same quantity of the
material employed as solvent, as also that used as precipitant, is used continuously
over again, so that there is only a very small loss of the substances during the
process.
The above named substances required to react on each other can also be treated
under pressure, with or without the presence of water and at a sufficiently high
temperature, and the product obtained can then be further treated as above
described.
Lastly, it is to be observed that the addition of chloride of calcium, strontia or
barium, first above mentioned, to the phosphates of iron, alumina and manganese

page_text: can be replaced by mixtures of chlorides of soda or potash with sulphate of lime,
strontia, celestine and magnesia; the described conversion is effected directly and
just as quickly under heating to a high red heat either with the exclusion or in the
presence of air or steam.
Phosphate of lime chloride of iron and sulphate of soda or potash are thus formed
according to the equation:
'
Fe, (PO), +3 Ca SO. + 6 Na Cl:
=
Ca, (PO), Fe, Cl, + 3 Na SO, the chloride of iron being decomposed as
described, while the sulphate is separated by lixiviation.
If sulphates of baryta or strontia are used, then by decomposing the corresponding
phosphate produced, and by precipitating either, with oxide of manganese, oxide of
iron or metallic iron or alumina, the phosphoric acid can be made to combine with
these and be precipitated, and the phosphate obtained can be again used for con-
verting the above substances, while the solution which contains chloride of strontia
can, after separation according to the usual method of any chloride of iron it contains,
for the production of chloride of strontia, be utilised either as such, or as carbonate.
Or the solution of bydrochloric acid is precipitated with lime, the strontia &c
which remains in solution, being obtained directly therefrom either by the
introduction of carbonic acid or by crystallisation.
The phosphates of iron also combine although slowly and not perfectly, with the
phosphates of lime, strontia, baryta and magnesia, either with or without the
presence of air or steam, and at a high temperature (red heat) forming phosphatic
earths and oxysulphates of iron &c, the latter being again converted into sulphuric
anhydride or sulphuric acid and oxide of iron. The former can be obtained in the
known manner and the oxides of iron can be separated in the hereinbefore described
manner from the phosphates.
The reaction with gypsum, celestine and heavy spar can be facilitated by the
addition of Na, SO, and K. SO,, which, in melting, increase the action of the
phosphatic earths.
.
In like manner may be be treated all the arseniate compounds of iron.
Instead of gypsum, celestine and heavy spar a mixture of chloride of calcium,
chloride of magnesium, chloride of strontia and chloride of barium with sulphate of
magnesia, sulphate of soda, or sulphate of potash can be used.