IMPROVE- MENTS IN PURIFYING NATURAL PHOSPHATES OF LIME
Year: 1858

page_text: LETTERS PATENT to William Clark, of 58, Chancery Lane, in the County
of Middlesex, Engineer & Patent Agent, for the Invention of "IMPROVE-
MENTS IN PURIFYING NATURAL PHOSPHATES OF LIME."-A communication
from Emile Constant Martin, residing at Paris, in the Empire of France,
formerly Banker.
Sealed the 15th March 1859, and dated the 25th September 1858.
PROVISIONAL SPECIFICATION left by the said William Clark at the
Office of the Commissioners of Patents, with his Petition, on the
25th September 1858.
I, WILLIAM CLARK, of 53, Chancery Lane, in the County of Middlesex,
Engineer & Patent Agent, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN PURIFYING NATURAL PHOSPHATES OF LIME," to be as
follows:-
Natural phosphates of lime are generally found in an impure state, their
richness being variable, some containing seventy-five per cent., while others
contain but seven, ten, or twenty per cent. of phosphate.
It is this infinite variety of richness which prevents its being utilised to the
extent it otherwise would attain if always of rich quality.
It is very inconvenient, if not impossible, to carry to great distances a
substance containing eighty or ninety parts of extraneous matters, the presence
of which matters are foreign to the purposes of the natural phosphate of lime,
and prevents its action in artificial manures, which is otherwise so efficacious
in principle; for this reason, manufactures of artificial manure have not

page_text: succeeded in obtaining the whole available quantity of phosphates to meet the
expectations of science and the purposes of agriculture. To obviate these
serious inconveniences, and to overcome the difficulties presented to the
developement of a rising branch of manufacture, is the object of this Invention.
Two methods are adapted for their purification, according to this Invention.
The first method is based on the difference of density of phosphates & of silica,
& results in a complete elimination of this latter substance. The second
method consists of making use of the carbonates of lime contained in them, and
by dissolving them by means of a slightly acidulated liquor.
To obtain these two results, the quantity of carbonate of lime which is
mixed with the phosphates is ascertained by analysis; this being done, a
quantity of pyroligneous acid s added to the water employed in the aperation,
or hydrochloric acid in a sufficient quantity to decompose the carbonate of
lime, and transform them into chloride of calcium.
The weight of water should be at least double the weight of the phosphates
to be treated, the whole being placed in a suitable receptacle, the mass is then
violently agitated for three or four minutes by means of a stirrer of agitator of
new kind, forming a part of this system, so as to separate the matters; it is
afterwards allowed to precipitate itself for any suitable time, & according to
the quantity of phosphate treated and to the power of the agitator; the liquid
is then, while yet thick, and having the carbonate & phosphate of lime in
suspension, received into a second receptacle. The silica remaining in the first
receiver being of greater density than the phosphate, will be quickly pre-
cipitated. The whole operation is repeated several times, but employing
unacidulated water, and always leaving the liquid in the second receiver
completely at rest, so as to obtain a complete precipitation; when the water in
the second receiver becomes entirely clear, it is poured off and the precipitate
obtained; it will consist of phosphate of lime in nearly a pure state, which
may then be formed into squares or bricks, which are piled one on the other,
and on which a current of air is passed if the atmosphere be to damp to
dry them.
If a prompt desiccation is required, or if it is wished to color the phosphate,
soot may be employed, which, independently of its agricultural richness (one
thirty-five of azote), acts like coal as an energetic disinfectant. It is almost
unnecessary to observe that in all manufacturing towns soot is found in
abundance.
The general construction of apparatus is as follows:-
1st. The first vat or tubs containing an agitator or stirrer formed of pallets,
which are crossed by the same sort of fixed pallets attached to the inner sides

page_text: of the vat or tub, and thus producing a very energetic stirring or agitating
operation.
2ndly, the stirrer is formed of two pieces in its length, the upper part being
always movable, while the lower part can be fixed so as not to disturb the
deposit of the silicious matters.
3rdly, the tub or vat in which the phosphate is deposited may be arranged
as a filter, so as to immediately separate as much water as possible. The filter
may be of felt, cloth, &c.
4thly, for immediately drying the thick matters consisting of the phosphate
in a nearly pure state, drying turbines are used, the sides of which are
lined with felt or cloth, and which filter and express the water by centrifugal
force; an immediate desiccation being thus obtained.
5thly, for mixing the dried matters with soot a mixing vat is employed, with
conical stones and scrapers, similar to those employed in the manufacture of
chocolate.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Clark in the Great Seal Patent Office on the
21st March 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
CLARK, of 53, Chancery Lane, in the County of Middlesex, Engineer and
Patent Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fifth day of September, in the year of our Lord
One thousand eight hundred and fifty-eight, in the twenty-second year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said William Clark, Her special licence that I, the said William
Clark, my executors, administrators, and assigns, or such others as I, the said.
William Clark, 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
PURIFYING NATURAL PHOSPHATES OF LIME," a communication, upon the
condition (amongst others) that I, the said William Clark, 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

page_text: nature of the said Invention, and in what manner the same was to be per-
formed, 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 William Clark, do hereby declare
the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement, that is to say:-
This Invention consists in purifying natural phosphates of lime, which are
generally found in an impure state, their richness being very variable, some
containing seventy-five per cent., while others contain but seven, ten, or twenty
per cent. of phosphate.
It is this infinite variety of richness which prevents its being utilised to the
extent it otherwise would attain if always of rich quality.
It is very inconvenient, if not impossible, to carry to great distances a
substance containing eighty or ninety per cent. of extraneous matter, the
presence of which matters are foreign to the purposes of the natural phosphate
of lime, and prevent its action in artificial manures, which is efficacious in
principle; for this reason, manufacturers of artificial manures have not
succeeded in obtaining the whole available quantity of phosphates to meet the
expectations of science and the purposes of agriculture. To obviate these
serious inconveniences or to overcome the difficulties presented to the develop-
ment of a rising branch of manufacture, I make use of two methods for their
purification; the first method is based on the difference of density of phosphates
and of silica, and results in a complete elimination of this latter substance.
The second method consists in making use of the carbonates of lime contained
in them, and dissolving them by means of a slightly acidulated liquor.
To obtain these two results, the quantity of carbonate of lime which is mixed
with the phosphates is ascertained by analysis. This being done, a quantity
of pyroligneous acid is added to the water employed in the operation, or hydro-
chloric acid in a sufficient quantity to decompose the carbonates of lime, and
transform them into chloride of calcium. The weight of water should be at
least double the weight of the phosphates to be treated.
.
The whole being placed in a suitable receptacle, the mass is then violently
agitated for three or four minutes by means of a stirrer or an agitator of a new
kind, forming a part of this system, so as to separate the matters; it is after-
wards allowed to precipitate itself for any required length of time, and according
to the quantity of phosphate treated and the power of the agitator; the
liquid is then, while yet thick, and having the carbonate and phosphate of lime

page_text: in suspension, received into a second receptacle. The silica remaining in the
first reciever being of greater density than the phosphate will be quickly
precipitated. The whole operation is repeated several times, but employing
unacidulated water, and always leaving the liquid in the second reciever
completely at rest, so as to obtain a complete precipitation.
Lastly, when the water in the second reciever becomes entirely clear, it is
poured off, and the precipitate obtained will consist of phosphate of lime in
nearly a pure state, which may then be formed into squares or bricks, which
are piled one on the other, and on which a current of air is passed if the
atmosphere be too damp to dry them.
If prompt dessication is required, or it is wished to color the prosphate,
soot may be employed, which, independently of its agricultural richness (1.35
of azote), acts like charcoal, viz., as an energetic disinfectant. It is almost
unnecessary to observe that in all manufacturing towns soot is found in
abundance.
The general construction of apparatus is as follows:-
First, the first vat or tub contains an agitator or stirrer formed of arms or
pallets, which are crossed by the same sort of fixed blades or pallets attached
to the inner sides of the vat or tub, and thus producing a very energetic
stirring or agitating operation.
Secondly, the shaft of the stirrer is formed of two pieces in its length;
the upper part being always movable, while the lower part can be fixed, so as
not to disturb the deposit of the silicious matter.
Thirdly, the tub or vat in which the phosphate is deposited may be arranged
as a filter, so as to immediately separate as much water as possible. The filter
may be of felt, cloth, &c.
Fourthly, for immediately drying the thick matters, consisting of the
phosphate in a nearly pure state, centrifugal drying machines or turbines are
used, the sides of which are lined with felt or cloth, and which filter and
express the water by centrifugal force, an immediate separation of the
moisture being thus obtained.
Fifthly, for mixing the dried matters with soot a mixing vat is employed,
with conical stones and scrapers, similar to those employed in the manufacture
of chocolate.
Having described the nature of the Invention and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein-before in part recited Letters Patent is,-
First, the purification of phosphates of lime for the purpose of rendering
them easier of transportation and assortment by treating them with an acid

page_text: such as hydrochloric acid, for example, for the purpose of eliminating the
carbonates combined therewith.
Secondly, the purification of phosphates charged with silica or silicates, by
agitating them in water for the purpose of precipitating the silica, and then
decanting the muddy liquid which contains the phosphate of lime in a pure
state, as described.
Thirdly, drying phosphates of lime, purified as described, in a stove or in
drying turbines or machines.
In witness whereof, I, the said William Clark, have hereunto set my
hand and seal, this Twenty-first day of March, in the year of our
Lord One thousand eight hundred and fifty-nine.
Witness,
W. E. SWINNOCK,
53, Chancery Lane.
W. CLARK. (L.S.)