IMPROVEMENTS IN THE TREATMENT OF CRUDE AND MINERAL PHOSPHATES OF LIME FOR THEIR CONVERSION INTO POTENTIAL FERTILIZING " to be as PRODUCTS, AND IN THE RECOVERY OF A MATERIAL EMPLOYED THEREIN
Year: 1871

page_text: PROVISIONAL SPECIFICATION left by Campbell Morfit at the Office
.
of the Commissioners of Patents, with his Petition, on the 27th
May 1871.
I, CAMPBELL MORFIT, of Baltimore, in the State of Maryland, United
States of America, but at present of 35, Southampton Buildings, in
the County of Middlesex, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN THE TREATMENT OF CRUDE AND MINERAL
PHOSPHATES OF LIME FOR THEIR CONVERSION INTO POTENTIAL FERTILIZING
" to be as
PRODUCTS, AND IN THE RECOVERY OF A MATERIAL EMPLOYED THEREIN,
follows:-
My Invention relates to the chemical treatment of crude and mineral
phosphates of lime for their conversion into potential fertilizing products
and in the recovery of a material employed therein.
The mode of carrying out my improvements is as follows:-I take the
crude or mineral phosphate of lime in fine powder and digest it with
sufficient hydrochloric acid to dissolve out all of its phosphate of lime
and carbonate of lime constituents. The solution thus formed is then
decanted, after which the insoluble residue is washed with fresh water.

page_text: This wash liquor is then decanted and mixed with the previous strong
liquor which combined form the "solution." The solid residue after
this washing consists of sand, silex, organic matter with most of the
fluoride of calcium, alumina, and oxide of iron of the raw mineral or
material and is to be thrown aside as waste. The solution is now to be
put into a vat and treated with caustic ammonia until a precipitate
ceases to form. By this operation all of the hydrochloric acid which
holds the phosphate of lime in solution is neutralized, and consequently
the latter falls as a precipitate, leaving above a liquor consisting of
chloride of calcium and chloride of ammonium. This liquor is to be 1
drawn off and the precipitate washed once, twice, or thrice if necessary,
and each time with fresh water in order to cleanse it of chlorides of
calcium and ammonium. These wash waters are to be mixed with the
previous strong liquor and held in reserve as the "wash." The pre-
cipitate is now nearly pure phosphate of lime of peculiar physical and 1
chemical structure, admirably suited for direct use as a potential
fertilizing material, or as a superior material for the manufacture of
high grades of "superphosphate."
When intended for direct use it must be steamed with a small per-
centage of sulphate of ammonia or sulphate of potassa, in order to ?
remove any hygroscopic tendency which it might have through the
retention of traces of chloride of calcium. The alkaline chloride thus
formed may be left in the precipitate to increase its pecuniary and agri-
cultural value, or it may be washed out with water and recovered
separately by evaporation, as may be preferred. In either case the 2
precipitate after the treatment with alkaline sulphate must be run upon
the bed of a kiln and dried for market. On the other hand, when the
precipitate is to be converted into "superphosphate," it is ready to
receive its dose or chemical equivalent of sulphuric acid, immediately
after the washing with water, and is to be passed through the mixer in
its pulpy state. In this form its decomposition is much more prompt
and thorough than usual, and the resulting "superphosphate" is of the
highest possible strength.
For the inaugural operation the ammonia must be generated from
gas liquor, sulphate of ammonia, or chloride of ammonium by dis-
tillation with lime, but according to my Invention in all subsequent
repetitions the "wash" is to be utilized for the purpose. To this end I
evaporate the "wash" to small volume or to dryness, mix it with the

page_text: requisite portion of slaked lime and distil it by means of a naked fire
or by steam currents. The lime and heat are thus made to take away
the acid element of the ammonia salt and drive over the liberated
ammonia gas. The gas may be passed directly into the hydrochloric
solution of the raw phosphate or condensed in water and then applied
in this liquid form as the precipitant. After the expulsion of all of the
ammonia from the generator, the residue, consisting of chloride of
calcium and lime, may be thrown out as waste or reserved for the
reclamation of its chloride of calcium by solution in water and evapo-
ration, in case there should be a market for the latter.
By thus making the "wash" of a previous operation serve as the
source of ammonia for a succeeding batch of solution, the precipitation
may be continued an indefinite number of times without further cost for
the ammonia than is incurred at the inaugural step.