IMPROVEMENTS IN PURIFYING NATURAL PHOSPHATES OF LIME
Year: 1859

page_text: PROVISIONAL SPECIFICATION left by William Clark at the Office
of the Commissioners of Patents, with his Petition, on the 8th January
1859. A communication from Emile Constant Martin, residing at Paris,
in the Empire of France, formerly Banker.
I, WILLIAM CLARK, of 53, Chancery Lane, in the County of Middlesex,
Engineer & Patent Agent, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN PURIFYING NATURAL PHOSPHATES OF LIME," to be as
follows:
This Invention consists of various processes for the purification of. natural
phosphates of lime, to render them more soluble & easier of transportation,
which
processes are severally applicable according to the variable composition
of the phosphates of lime.
First process. Applicable for lumps of natural phosphates containing from
fifteen to twenty per cent. of carbonate of lime.-The phosphate of lime is placed
in suitable receivers, furnished with agitators, either in lumps or in a pulverized
state with acetic acid produced, for example, from the carbonization of wood
-(pyroligneous acid). This acetic acid decomposes the carbonates of lime,
which it forms into volatile carbonic acid & acetate, soluble in an excess of
acetic acid, which latter is removed from the receptacle by decanting the
liquids. There remains as residue pure phosphate of lime, with silica or with
silicates, which are separated by means of their difference of density in the

page_text: apparatus described in the Provisional Specification of a Patent applied for by
me, and dated the Twenty-fifth day of September 1858. These residues may
also be treated by means of hydrochloric acid, which dissolves the phosphate
alone, leaving as residue the silica and silicates, which are separated by decan-
tation. The solution of phosphate of lime by hydrochloric acid is placed in a
closed vessel into a retort, furnace, or other suitable capacity, when it is heated
and stirred up; the acid volatilizes, & is condensed to serve for other similar
operations, there remaining in the retort the phosphate of lime in powder & in a
Five or six per cent. of lime may be added to the mixture while
in the furnace, which forms thus a tri-basic phosphate of lime, as phosphate of
bones, which is more easily assimilated to plants.
pure state.
2nd process. The phosphate of lime in powder is placed in a furnace,
retort, or similar capacity, with hydrochlorate of ammonia, & then heated;
this hydrochlorate volatilizes & decomposes the carbonates of lime, with which
it forms chloride of calcium & carbonate of ammonia. This volatile carbonate
of ammonia is condensed, and treated cold by means of chloride of magnesium
or calcium, which regenerates the hydrochlorate of ammonia for other similar
purposes. The chloride of calcium which remains with the phosphate & the
silica is removed by washing with water. The residue is then composed of
silica or silicates & phosphate of lime, which are separated, as in the first
process, by washing and decanting, or by treating it with hydrochloric acid.
3rd process. The natural phosphate of lime in powder is placed in a
furnace, retort, or other similar capacity, with chloride of magnesium or
chloride of iron, or chloride of lead, or of aluminium, or with any other volatile
chloride, & then heated. If chloride of magnesium is employed it decomposes
& forms with the carbonates of lime chloride of calcium & carbonate of
magnesia. The chloride of calcium is removed by washing; there then remains
the phosphate of lime & the silica or silicates, which are separated as in the
two former processes.
4th process. Unbroken lumps of the phosphate are placed into suitable
receptacles furnished with mechanical agitators with hydrochloric acid. This
acid decomposes the carbonates of lime, disengages the carbonic acid, & forms
chloride of calcium, at the same time it dissolves all the phosphate of lime, &
leaves the silica or silicates, which are separated by decantation. The pasty mix-
ture of chloride of calcium & phosphate of lime dissolved in hydrochloric acid is
treated in a furnace, retort, or other capacity, as in the preceding processes, to
volatilize the acid, which is condensed to serve again for similar operations.
The pulverulent mixture of phosphate of lime & chloride. of calcium which

page_text: remains is treated with water, which dissolves the chloride of calcium, &
leaves the phosphate of lime in a pure state, which may be dried in a stove or
hydro-extractor. Any other volatile acid may be used for dissolving the
phosphate of lime. In this process, as in the preceding processes, from four
to five per cent. of lime is added to change the phosphate from a bi-basic to
a tri-basic condition.