AN IMPROVED TREATMENT OF NATURAL PHOSPHATE OF LIME FOR SEVERAL PURPOSES
Year: 1861

page_text: PROVISIONAL SPECIFICATION left by Auguste César Achille Gérard de
Melcy at the Office of the Commissioners of Patents, with his Petition,
on the 11th May 1861.
I, AUGUSTE CÉSAR ACHILLE GÉRARD DE MELOY, of Paris, in the French
Empire, Gentleman, do hereby declare the nature of the said Invention for
"AN IMPROVED TREATMENT OF NATURAL PHOSPHATE OF LIME FOR SEVERAL
PURPOSES," to be as follows:-
The object of my Invention is to treat natural phosphate of lime in order to
produce phosphate of lime and carbonate of soda. In treating phosphate of
In
lime by sulphuric acid, the greater part of the phosphoric acid is set free.
the different modes of treating phosphatic matters hitherto adopted this free
acid has not been utilized. I have discovered that it can be employed for the
decomposition of sea salt, and the transformation of the same into phosphate
of soda. I proceed in the following manner:-
I treat phosphate of lime in the state of nodules, coprolites, apatites, all the
mineral phosphates, or even bones pulverized or ground by a quantity of
sulphuric acid diluted to sufficient strength to expel all the phosphoric acid.
The quantity of sulphuric acid will vary according to the richness in phos-
phates, carbonates, oxides, and other matters of the phosphatic materials
employed. I leave the matters in contact about 24 hours, and stir them
frequently. I then allow to settle, and decant the liquid. The residue is
washed, and the wash-water is added to the decanted liquid. When the wash-
water is not sufficiently charged with useful products it is reserved to dilute

page_text: the sulphuric acid employed in treating a fresh quantity of phosphate. The
decanted liquid and the wash-waters mixed with it contain acid phosphate o
lime, free sulphuric acid, free phosphoric acid, and a certain quantity o
plaster, as well as phosphate of iron dissolved by the free acids and sulphate
of iron. The two last-named salts may be employed in the preparation o
Prussian blue, by adding to them ferrocyanide of potassium. The above
liquor is evaporated in ovens or cylinders. I add to it sea salt in sufficient
quantity to allow of the soda resulting from its decomposition neutralizing the
free acids of the solution. This reaction commences when evaporation has
ceased. It is manifested by an abundant disengagement of muriatic acid
which may be collected, and ceases when no more acid is disengaged. The
mass resulting from the above treatment is dissolved in water, it is composed
of sulphate and phosphate of soda, of insoluble sulphate of lime, and phosphate
of iron also insoluble; it contains also acid phosphate of lime. I decant the
liquid part from the insoluble residue, and then add to the liquid a quantity of
lime. The quantity should be carefully regulated in relation to the amount of
phosphate in the liquor. I add about 118 lbs. of lime weighed in the state of
quick lime, and afterwards reduced to the consistency of thin paste to pre-
cipitate a liquor containing about 220 lbs. of phosphate of soda, supposed to
be dry (2 NaO, Pho³, HO). I complete the reaction of the lime on the
solution of alkaline phosphate by frequent stirrings for about 24 hours. I
then leave it to deposit the precipitate, which will be formed of phosphate of
lime. I decant the liquid, which contains free soda, and I add to it the wash-
waters of the precipitate of phosphate of lime. The latter is then dried. The
liquid, which besides caustic soda, may still contain some sulphate of soda,
may be used as a soda lye, or it may be transformed into carbonate of soda by
treating it with smoke which has been previously washed. By evaporating
afterwards and crystallizing I obtain salts of soda.
In the foregoing treatment chloride of potassium may be substituted for
chloride of sodium. Any of the salts of potass, or of soda formed by an acid
capable of displacement by phosphoric acid, nitrates, carbonates, acetates, or
pyrolignites may also be employed.