IMPROVEMENTS IN THE PRODUCTION OF SOLUBLE PHOSPHATES OF LIME.” IN THE PRODUCTION OF SOLUBLE PHOSPHATES OF Lime
Year: 1875

page_text: LETTERS PATENT to John Thomas Way, of 9, Russell Road, Kensington,
in the County of Middlesex, for the Invention of "IMPROVEMENTS
IN THE PRODUCTION OF SOLUBLE PHOSPHATES OF LIME.”
IN THE PRODUCTION OF SOLUBLE PHOSPHATES OF Lime.”
"
PROVISIONAL SPECIFICATION left by the said John Thomas Way at
the Office of the Commissioners of Patents, with his Petition, on
the 24th February 1875.
I, JOHN THOMAS WAY, of 9, Russell Road, Kensington, in the
County of Middlesex, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN THE PRODUCTION OF SOLUBLE PHOSPHATES OF LIME,"
to be as follows:-
This Invention consists in improvements, 1st, in the methods of pro-
ducing crystalline compounds of chloride of calcium with acid or mono-
phosphate of lime, to which in my Patent dated 14th July, 1871,
No. 1851, I have given the name of chloro-phosphate of lime; and, 2nd,
of treating these compounds so as more or less to remove from them the
chloride of calcium and render the product more available for manure

page_text: applied.
In the Patent above referred to I have described several methods of
producing the chloro-phosphate of lime, but I have found the following
to be more practicable and economical:-I take any form of ordinary
phosphate of lime, and having reduced it to powder I mix with it hydro-
chloric acid of a strength of from 25 per cent. upwards, in the proportion
of two equivalents or combining proportions of and to one equivalent of
phosphate of lime, allowing an extra proportion of acid. Where carbonate
of lime is present with the phosphate I continue to stir the acid
with the phosphate until the mixture thickens. In this way a thick
paste is produced, which after standing a day or two will be found
when treated with water to be readily and entirely soluble except as to
sand or other like impurities. I may mention in passing that this
method is well adapted to obtaining a solution of phosphate of lime in
hydrochloric acid as in the case of my Patent for the production of
di-phosphate of lime.
When I have ascertained by trial on small quantities that the whole
or greater portion of the phosphate of lime has been rendered soluble I
mix with the paste a quantity of water varying from 5 to 15 per cent.
of its weight, in some cases making a further addition of hydrochloric
acid to the extent of 1 or 2 per cent. of the weight of the paste. After
a few hours I find that crystals of chloro-phosphate have formed together
with a liquid which is principally a solution of chloride of calcium but
containing some soluble phosphate of lime. I separate the liquor from
the crystals by draining, aided by a vacuum or by pressure. The solid
product is chloro-phosphate of lime with adhering chloride of calcium,
and any insoluble matters, sand, &c., that has been present in the crude
phosphate employed.
I recover the phosphate of lime from the liquor by evaporation, or, by
preference, in the form of di-phosphate or tri-phosphate of lime by
precipitation by chalk or lime. The precipitated phosphate of lime may,
if desired, be returned into the process with further batches of crude
phosphate.
In cold weather, or if the mixture of phosphate of lime and acid be
artificially cooled, in place of a paste being formed the crystals will be
obtained, and then a stage in the operation is saved, and I proceed with

page_text: the separation of the crystals from the liquid as already described. I
employ the chloro-phosphate so made as manure, or after addition to it
of sulphate of ammonia, or of sulphuric acid, or of both; when adding
sulphuric acid I subject the mixture to heat to drive off free hydrochloric
acid. I also convert the chloro-phosphate into di-phosphate of lime by
heating it to a temperature above 300° Fahrenheit, but not exceeding
500° Fahrenheit or thereabouts.
The second part of my Invention consists of methods of removing from
chloro-phosphate of lime the whole or a portion of the chloride of calcium.
I have found that when the chloro-phosphate is treated with a quantity
of water, less than sufficient to dissolve it, the chloride of calcium is
dissolved in larger proportions than the acid or mono-phosphate of lime,
so that if this treatment is carried on with successive small quantities of
water the solution being removed after each addition it is possible to
remove the whole, or nearly the whole, of the chloride of calcium,
leaving acid phosphate of lime as the solid product. In practice.
however I prefer to divide the process into several steps or stages, and to
treat the solid products of each stage by the liquid product of a more
advanced stage on the same principle though not necessarily in the same
manner as in the process known as lixiviation.
In order better to explain this I will suppose that I have a series
of compounds commencing with acid phosphate of lime itself at the
head of the series, followed by compounds containing larger and larger
proportions of chloride of calcium. Thus A will represent acid phosphate
of lime; B, acid phosphate of lime with 5 per cent. of chloride of
calcium; C, with 10 per cent.; D, with 15 per cent.; and E, with
20 per cent. I treat B with a strong solution of A, and having removed
the resulting liquor which will contain the chloride of calcium I have a
solid product of practically pure acid phosphate of lime. With the
liquor derived from this operation I treat C, which in its turn loses
chloride of calcium and becomes B, and so on to the end of the series.
In this series D represents the crystals of chloro-phosphate, and E the
paste before described. The result of this method of treatment is the
gradual abstraction of the chloride of calcium with the smallest possible
loss of products in the shape of acid phosphate of lime in the final
liquor; this I recover by precipitation, or otherwise, as before described.
To commence operations I provide a stock of solution of acid phosphate
of lime, and with this I operate on the crystals or the paste till the solid

page_text: products and liquors divide themselves naturally into some such series as
I have supposed.
In carrying out the process I separate the liquors from the solid pro-
ducts by filtration aided by the pressure of air by a Needham's or other
press, or by centrifugal force. I use the acid phosphate when thus
partly or entirely freed from chloride of calcium for manure or for other
purposes.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Thomas Way in the Great Seal Patent Office
on the 23rd August 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
THOMAS WAY, of 9, Russell Road, Kensington, in the County of Middle-
sex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fourth day of February, in the
year of our Lord One thousand eight hundred and seventy-five, in the
thirty-eighth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John Thomas Way, Her special license
that I, the said John Thomas Way, my executors, administrators, and
assigns, or such others as I, the said John Thomas Way, my executors,
administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thereafter during the term
therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
THE PRODUCTION OF SOLUBLE PHOSPHATES OF LIME," upon the condition
(amongst others) that I, the said John Thomas Way, my executors or
administrators, by an instrument in writing under my, or their, or one of
their hands and seals, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to
be performed, and cause the same to be filed in the Great Seal Patent
Office within six calendar months next and immediately after the date
of the said Letters Patent.
NOW KNOW YE, that I, the said John Thomas Way, do hereby
declare the nature of the said Invention, and in what manner the

page_text: same is to be performed, to be particularly described and ascertained
in and by the following statement thereof, that is to say :—
This Invention consists in improvements, first, in the methods of pro-
ducing crystalline compounds of chloride of calcium with acid or mono-
phosphate of lime, to which in my Patent dated 14th July, 1871,
No. 1851, I have given the name of chloro-phosphate of lime; and
second, in treating these compounds so as more or less to remove from
them the chloride of calcium and render the product more available for
manure and for other uses to which soluble phosphate of lime is or may
be applied.
In the Patent above referred to I have described several methods of
producing the chloro-phosphate of lime, but I have found the following
to be more practicable and economical :-I take any form of ordinary
phosphate of lime, and having reduced it to powder I mix with it hydro-
chloric acid of a strength of from 25 per cent. upwards, in the proportion
of two equivalents or combining proportions of acid to one equivalent of
phosphate of lime, allowing an extra proportion of acid. Where carbonate
of lime is present with the phosphate I continue to stir the acid with
the phosphate until the mixture thickens. In this way a thick paste is
produced, which after standing a day or two will be found when treated
with water to be readily and entirely soluble, except as to sand or other
like impurities. I may mention in passing that this method is well
adapted to obtaining a solution of phosphate of lime in hydrochloric
acid, as in the case of my Patent for the production of di-phosphate of
lime.
When I have ascertained by trial on small quantities that the whole
or greater portion of the phosphate of lime has been rendered soluble I
mix with the paste a quantity of water, varying from 5 to 15 per cent.
of its weight, in some cases making a further addition of hydrochloric
acid to the extent of 1 or 2 per cent. of the weight of the paste.
After
a few hours I find that crystals of chloro-phosphate have formed together
with a liquid, which is principally a solution of chloride of calcium, but
containing some soluble phosphate of lime. I separate the liquor from
the crystals by draining, aided by a vacuum or by pressure. The solid
product is chloro-phosphate of lime with adhering chloride of calcium,
and any insoluble matter, sand, &c., that has been present in the crude
phosphate employed.

page_text: I recover the phosphate of lime from the liquor by evaporation, or by
preference in the form of di-phosphate or tri-phosphate of lime by
precipitation, by chalk lime the precipitated phosphate of lime may
if desired be returned into the process with further batches of crudo
phosphate.
In cold weather, or if the mixture of phosphate of lime and acid be
artificially cooled, in place of a paste being formed the crystals will be
obtained, and then a stage in the operation is saved, and I proceed with
the separation of the crystals from the liquid, as already described. I
employ the chloro-phosphate so made as manure, or after addition to it
of sulphate of ammonia, or of sulphuric acid, or of both, when adding
sulphuric acid I subject the mixture to heat to drive off free hydro-
chloric acid. I also convert the chloro-phosphate into di-phosphate of
lime by heating it to a temperature above 300° Fahrenheit, but not
exceeding 500° Fahrenheit, or thereabouts.
The second part of my Invention consists of methods of removing
from chloro-phosphate of lime the whole or a portion of the chloride of
calcium. I have found that when the chloro-phosphate is treated with
a quantity of water, less than sufficient to dissolve it, the chloride of
calcium is dissolved in larger proportion than the acid or mono-phos-
phate of lime, so that if this treatment is carried on with successive
small quantities of water the solution being removed after each addition
it is possible to remove the whole or nearly the whole of the chloride of
calcium, leaving acid phosphate of lime as the solid product. In practice
however I prefer to divide the process into several steps or stages and
to treat the solid product of each stage by the liquid product of a more
advanced stage on the same principle, though not necessarily in the
same manner as in the process known as lixiviation.
In order better to explain this I will suppose that I have a series of
compounds commencing with acid phosphate of lime itself at the head
of the series, followed by compounds containing larger and larger pro-
portions of chloride of calcium. Thus A will represent acid phosphate
of lime; B, acid phosphate of lime with 5 per cent. of chloride of
calcium; C, with 10 per cent. ; D, with 15 per cent.; and E, with 20
per cent. I treat B with a strong solution of A, and having removed
the resulting liquor which will contain the chloride of calcium I have a
solid product of practically pure acid phosphate of lime. With the

page_text: liquor derived from this operation I treat C, which in its turn loses
chloride of calcium and becomes B, and so on to the end of the series.
In this series D represents the crystals of chloro-phosphate, and E the
paste before described. The result of this method of treatment is the
gradual abstraction of the chloride of calcium with the smallest possible
loss of product in the shape of acid phosphate of lime in the final liquor.
This I recover by precipitation or otherwise as before described. To
commence operations I provide a stock of solution of. acid phosphate of
lime, and with this I operate on the crystals or the paste till the solid
products and liquors divide themselves naturally into some such series
as I have supposed.
In carrying out the process I separate the liquors from the solid
products by filtration aided by the pressure of air by a Needham's or
other press or by centrifugal force. I use the acid phosphate when
thus partly or entirely freed from chloride of calcium for manure or for
other purposes.
In carrying out my Invention I mix the ground phosphate with the
hydrochloric acid in any convenient vessel either by hand or by suitable
stirring arrangements. The vessel may be of stone, such as is used in
alkali works, for the storage of hydrochloric acid, and in making chlorine
stills; or of wood pitched or lined with lead, iron vessels unless lined
are unsuitable for the purpose; or the materials may be mixed in a tank
or hollow floor made of brick and coated with asphalte.
The acid and phosphate may be mixed in large quantities or when
mechanical stirring is adopted in batches of two or three tons at a time.
For this latter purpose the mixers employed in making superphosphate
answer perfectly well provided that the surface exposed to the action of
the acid is not of iron. The proportions of phosphate and acid must be
regulated according to the composition of the phosphate and the strength
of the acid. I have already said that the guiding principle of the process.
is to use two equivalents of acid to one of tribasic phosphate present, if
less than this is used the phosphate will not all be dissolved, if more
free phosphoric acid will be formed and the product of crystals reduced.
I prefer however to use a slight excess of hydrochloric acid over the
3 two equivalents, as the phosphate is more perfectly dissolved, and the
only objection is that there is somewhat more phosphate to be subse-
quently precipitated from the liquor.
An additional quantity of acid is also to be added to neutralize car-

page_text: bonate of lime present in the mineral posphate. I will give an illus-
tration of the proportions to be employed under given circumstances:-
If the raw phosphate contain 70 per cent. tribasic phosphate of lime
and five per cent. of carbonato of lime, and the acid have a density
of 27° Fronddell (or 27° real acid), then the proportions are thus
ascertained, One equivalent of tribasic phosphate of lime (155 parts)
will be contained in 221 parts of raw phosphate. The phosphate at 5
per cent. will contain 11 parts of carbonate of lime; 133 parts of hydro-
chloric acid of 27° will contain 36 parts (or 1 equivalent) of real H Cl.
To neutralize the carbonate 29 lbs. of acid will be required, and for the
phosphate 266 parts, together 295 parts. If these quantities be mul-
tiplied by 10 the result will practically represent the proportions for 1
ton (2240 lbs.) of raw phosphate. So that in the case supposed to each
ton of ground phosphate 2950 pounds measure or 295 gallons of acid of
27° Fronddell would be required.
I prefer to use the acid cold, and to reduce the temperature resulting
from the chemical action by exposure to the air. For this reason I use
shallow vessels where practicable. I sometimes also cool the materials
during mixing, and subsequently by forcing cold air through them. The
air may be introduced through the shaft and arms of the agitator or
separately.
In order that the phosphate may be fully dissolved I continue the
stirring from time to time until a thick paste is produced, or until the
mixture becomes crystalline. If acid of 29° or 30° Fronddell has been
employed the paste will be very rapidly formed, and for this reason I use
the acid by preference as strong as possible. When by experiment I
find that the whole of the phosphate has been acted upon, I add to the
paste a small quantity of water and stir well together.
In the case
supposed I should add 25 gallons of water, or 5 per cent. If upon
standing for 12 hours no sign of crystallization appears, then a second
quantity of 25 gallons of water with 5 gallons of hydrochloric acid
should be added. It has already been stated that if the materials can
be sufficiently cooled the crystals will form at once, and occasionally
the paste when kept for some time will pass into the crystalline
condition.
Having obtained a crystalline compound of acid phosphate of lime
1
T
11

page_text: accompanies it. This may be accomplished in several ways. I construct
a tank of wood or of brick lined with asphalte or any material that is
not acted on by hydrochloric or phosphoric acid. In the bottom of the
tank I fix a grating of wood, upon which a coarse cloth is laid,
and upon
this again another grating to enable the workmen to use their spades
without injury to the cloth. I discharge the crystalline compound and
liquor into this tank, and allow the liquor to drain through the cloth.
By means of an air pump I draw the air out from beneath the false
bottom, meanwhile beating the material to fill up cracks, and in this way
I effect a separation of the liquor, and obtain a nearly dry mass of
crystals. The same result, is obtained by the use of a centrifugal
machine, which however must be protected from the action of the acids
by a coating of lead or otherwise.
It is obvious that I can at this stage treat the chloro-phosphate of lime
according to the second part of my Invention in order to remove from it
the whole or a part of the chloride of calcium. Accordingly if I desire
only to remove so much of this chloride as will give me a compound not
practically deliquescent I treat tho material on the cloth or in the centri-
fugal machine with successive small quantities of water, preserving the
liquor for precipitation.
I remove the crystalline products, which may be used as manure
without further treatment, or I dry it at a temperature not exceeding
212°, and in order still further to reduce the proportion of chloride of
calcium I add to the material, either before or after drying, from 5 to
10 per cent. of sulphuric acid, of sp. g. 1.70, or I mix with it any
desirable quantity of sulphate of ammonia, with or without such
addition of sulphuric acid. By heating the chloro-phosphate to a
temperature not exceeding 500° Fahrenheit I convert it into di-phosphate
of lime.
If I desire to remove the whole or nearly the whole of the chloride of
calcium I treat the chloro-phosphate, as already mentioned, on the
principle of lixiviation, preserving separately the liquor of each stage
of the process to be used to a subsequent portion of the material, as
will be sufficiently understood by persons familiar with chemical manu-
factures.
I collect the waste liquors of the process, which will contain con-