Improvements in Treating Phosphatic Minerals.
Year: 1890

page_text: Date of Application, 1st Apr., 1890
Complete Specification Left, 31st Dec., 1890-Accepted, 14th Feb., 1891
PROVISIONAL SPECIFICATION.
Improvements in Treating Phosphatic Minerals.
"
"I, LUDWIG MOND of "The Poplars
20 Avenue Road, Regents Park,
London, N.W., do hereby declare the nature of this invention to be as follows:-
This invention relates to the treatment of minerals containing phosphates and
carbonates, more particularly the phosphates and carbonates of lime, and has for
its object the elimination or reduction of the carbonates. For this purpose the
minerals are calcined to drive off carbonic acid. They are then mixed up with
water (or the liquid remaining from previous operations) and treated with sulphu-
retted hydrogen (the access of air being as much as possible excluded) so as to
convert the lime resulting from the calcination during the previous operation into
soluble calcium hydro-sulphide (Ca (SH) 2).
The insoluble residue, which contains all the phosphates is separated by filters or
centrifuges and washed with water. In order to recover the sulphuretted hydrogen
used in the previous operation, the solution of calcium hydro-sulphide is treated
with carbonic acid for which purpose the gases given off in calcining the original
-mineral may be used. A precipitate of carbonate of lime is thus formed and
sulphuretted hydrogen evolved, which is employed in treating a second batch of the
calcined mineral. To make up any loss of sulphuretted hydrogen, a quantity of
Le Blanc-alkali-waste may be added to the solution of calcium hydro-sulphide. In
order to drive off completely the sulphuretted hydrogen, the solution of calcium
hydro-sulphide may be heated during or after its treatment with carbonic acid,
but this is not necessary if the liquid resulting from the treatment with carbonic
acid in the cold is used in place of water for mixing up a fresh batch of the calcined
mineral.
Or the sulphuretted hydrogen may be recovered by heating or boiling the
solution of calcium hydro-sulphide for some time by means of steam or direct fire,
when sulphuretted hydrogen is given off and hydrate of lime separates out. It is
difficult in this way to drive off the sulphuretted hydrogen completely nor is this
necessary, as the solution, after a suitable quantity of sulphuretted hydrogen has
been driven out and the hydrate of lime separated from it, can be used in place of
water for mixing up a fresh batch of the calcined mineral.
In this way a certain quantity of calcium hydro-sulphide always remains in the
liquor and the second operation, to which a quantity of sulphuretted hydrogen
equivalent to this hydro-sulphide has to be added, will yield the full quantity of
this gas required for the third operation and so on, with the exception of a small
loss unavoidable in all such operations.
15
1900
COMPLETE SPECIFICATION.
Improvements in Treating Phosphatic Minerals.
I. LUDWIG MOND of "The Poplars * "20 Avenue Road, Regents Park,
London N.W. 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:-
This invention relates to the treatment of minerals containing phosphates and
carbonates, more particularly the phosphates and carbonates of lime, and has for its

page_text: as
object the elimination or reduction of the carbonates. For this purpose, the
minerals are calcined to drive off carbonic acid. They are then mixed up with
water (or the liquid remaining from previous operations) and treated with sulphu-
retted hydrogen (the access of air being as much as possible excluded) so
to convert the lime resulting from the calcination during the previous operation
into soluble calcium hydro-sulphide (Ca (SH) 2), which can be utilised for any
desired purpose, but I prefer to retain it to recover sulphuretted hydrogen there-
from, instead of having to form the latter specially from alkali waste or other raw
material.
The insoluble residue, which contains all the phosphates, is separated by filters
or centrifuges and washed with water. In order to recover the sulphuretted
hydrogen used in the previous operation, the solution of calcium hydro-sulphide is
treated with carbonic acid, for which purpose the gases given off in calcining the
original mineral may be used. A precipitate of carbonate of lime is thus formed
and sulphuretted hydrogen evolved, which is employed in treating a second batch
of the calcined mineral. To make up any loss of sulphuretted hydrogen, a quantity
of Le Blanc-alkali-waste may be added to the solution of calcium hydro-sulphide.
In order to drive off completely the sulphuretted hydrogen, the solution of calcium
hydro-sulphide may be heated during or after its treatment with carbonic acid, but
this is not necessary if the liquid, resulting from the treatment with carbonic acid
in the cold, is used in place of water for mixing up a fresh batch of the calcined
mineral.
Or the sulphuretted hydrogen may be recovered by heating or boiling the solu-
tion of calcium hydro-sulphide for some time by means of steam or direct fire,
when sulphuretted hydrogen is given off and hydrate of lime separates out. It is
difficult in this way to drive off the sulphuretted hydrogen completely, nor is this
necessary, as the solution, after a suitable quantity of sulphuretted hydrogen has
been driven out and the hydrate of lime separated from it, can be used in place of
water for mixing up a fresh batch of the calcined mineral..
•
In this way, a certain quantity of calcium hydro-sulphide always remains in the
liquor, and the second operation, to which a quantity of sulphuretted hydrogen.
equivalent to this hydro-sulphide, has to be added, will yield the full quantity of
this gas required for the third operation, and so on, with the exception of a small
loss unavoidable in all such operations.
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 -
1. The method of treating phosphatic minerals containing carbonates, which
consists in calcining them, mixing the resulting product with water and treating it
with sulphuretted hydrogen, thusdissolving out the lime andseparating the insoluble
residue from the liquid.
2. In the treatment of phosphatic minerals, utilising the carbonate of lime and
free lime contained therein for the manufacture of calcium hydro-sulphide, whereby
not merely is that valuable product obtained but the phosphates are concentrated
for further use.
3. In combination with the process substantially as set forth in Claim 1, the
regeneration and utilisation, in subsequent operations,-of-the-sulphuretted bydrogen
substantially as described.
WM. P. THOMPSON & Co.,
Of Liverpool, Manchester, Nottingham, and London, Patent Agents.