IMPROVED TREATMENT OF CERTAIN PHOSPHATES FOR THE ELIMINATION OF ALUMINA THEREFROM
Year: 1877

page_text: LETTERS PATENT to Charles Humfrey, of Hough Green, Chester, in the
County of Chester, for the Invention of "IMPROVED TREATMENT OF CERTAIN
PHOSPHATES FOR THE ELIMINATION OF ALUMINA THEREFROM."
ealed the 15th February 1878, and dated the 31st August 187
PROVISIONAL SPECIFICATION left by the said Charles Humfrey at the
Office of the Commissioners of Patents on the 31st August 1877.
CHARLES HUMFREY, of Hough Green, Chester, in the County of Chester.
"IM-
PROVED TREATMENT OF CERTAIN PHOSPHATES FOR THE ELIMINATION OF ALUMINA
THEREFROM."
My Invention relates to the treatment of those natural phosphates which contain
alumina, such as are found in the Island of Redonda in the West Indies.
I first calcine the phosphate at a moderate heat, and then grind and mix it in an
ordinary mortar mill with a solution of caustic soda of about 60° Twaddle in
quantity sufficient to form a tribasic phosphate of soda with all the phosphoric acid
present in the natural phosphate under treatment, and also with sufficient soluble
silicate of soda to form an insoluble compound with all the alumina. Considerable
heat is developed during the mixing.
After being thoroughly incorporated the mixture is allowed to stand for about 24
hours, when it forms into a solid cake or mass, which is afterwards lixiviated with
hot water and the insoluble portion allowed to settle, or the clear liquor filtered off.
The residue is rewashed with water till it is practically free from soluble matter.
The washings being completed the whole of the liquors are pumped to a vessel
provided with a perforated steam coil in the bottom, and steam passed in till there
is violent boiling, when sufficient lime made into a cream with water is added to
decompose the phosphate of soda, and to form an insoluble tribasic phosphate of
lime, leaving caustic soda in solution.
The precipitated phosphate of lime is washed with water till it is practically free
from soda, and then dried.

page_text: The soda solution and the washings from the precipitated phosphate of lime are
evaporated to about 60° Twaddle and used over again.
The insoluble residue containing the alumina combined with silica and soda (aud
all the insoluble matters of the original phosphate) is ground in a mortar mill with
lime, which decomposes the compound of alumina, silica, and soda, setting the latter
free;
this is washed out with water till the residue is practically free from soda.
The washings may be used in the place of water for washing the insoluble residue
of the first lixiviation, or they may be boiled up to 60° Twaddle and used over
again.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Charles Humfrey in the Great Seal Patent Office on the 28th
February 1878.
IM-
CHARLES HUMFREY, of Hough Green, Chester, in the County of Chester.
PROVED TREATMENT OF CERTAIN PHOSPHATES FOR THE ELIMINATION OF ALUMINA
THEREFROM."
My Invention relates to the treatment of those natural phosphates which contain
alumina, such as are found in the Island of Redonda in the West Indies.
I first calcine the phosphate at a moderate heat, and then grind and mix it in an
ordinary mortar mill with a solution of caustic soda (or potash) of about 60° Twaddle
in quantity sufficient to form a tribasic phosphate with all the phosphoric acid
present in the natural phosphate under treatment, and also with sufficient soluble
silicate of soda (or potash) to form an insoluble compound with all the alumina.
Considerable heat is developed during the mixing.
After being thoroughly incorporated the mixture is allowed to stand for about 24
hours, when it forms into a solid cake or mass, which is afterwards lixiviated with
hot water and the insoluble portion allowed to settle, or the clear liquor can be
filtered off. The residue is rewashed with water till it is practically free from
soluble matter.
The washings being completed the whole of the liquors are pumped to a vessel
provided with a perforated steam coil on the bottom, and steam passed in till there
is violent boiling, when sufficient lime, made into a cream with water, is added to
decompose the phosphate of soda (or potash), and to form an insoluble tribasic
phosphate of lime, leaving caustic soda (or potash) in solution.
The precipitated phosphate of lime is washed with water till it is practically free
from soda (or potash), and then dried.
The soda (or potash) solution and the washings from the precipitated phosphate
of lime are evaporated to about 60° Twaddle and used over again.
The insoluble residue containing the alumina combined with silica and soda or
potash (and all the insoluble matters in the original phosphate) is ground in a
mortar mill with lime, which decomposes the compound of alumina, silica, and soda
(or potash), setting the latter free; this is washed out with water till the residue is
practically free from soda (or potash).
The washings may be used instead of water for washing the insoluble residue of
the first lixiviation, or they may be boiled up to 60° Twaddle and used over again.
Having now described the nature of my Invention, and the manner in which the

page_text: same is to be carried out, I would have it understood that I do not confine myself
to the exact details, but I declare that I claim as my Improved Treatment of
certain Phosphates for the Elimination of Alumina therefrom,
First. The use of soluble silicate of soda or potash to render the alumina insoluble,
as set forth.
And, Secondly. Extracting the soda or potash from the insoluble compound of
alumina, silica, and soda or potash with lime, as described.
In witness whereof, I, the said Charles Humfrey, have hereunto set my hand
and seal, this Twenty-sixth day of January, One thousand eight hundred
and seventy-eight.
CHARLES HUMFREY. (L.S.)