The Marietta journal. [volume] (Marietta, Ga.) 1866-1909, 1905-11-23
The Acide Phosphate lndustry-A De
scriPton Of Process of Manufacture.

scriPtion Of Process of Manufacture.
The foundation of the great modern
industry of commercial fertilizers is
the manufacture of superpnosphate, or,
as it is more. generally known in this
country, Of acid phosphate of lime.
The materials necessary for this manu-
facture are sulphuric acid and phos-
plate rock. The plant required for
the manufacture of sulphuric acid is
a costly one, and the process is some
what complicated. Either birthstone
from Sicily, or pyrites, which is a
cimpound Of sulphur and iron, some of
which is imported from Spain and
some produced from mines in this
country, are the raw materials used in
the manufacture.
The birthstone or pyrites are burned
in specially constructed burners, and
the sulphurous gases which result from
the burning are caused to mix with
nitrous gases produced from nitrate OF
soda, and drawn into great towers
made of lead and packed with fints;
thence they are drawn into immense
leaden chambers or rooms, usually
three in row connected together. In
these chambers sulphurous and nitrous
gases are mixed with steam, and con-
densed into sulphuric acid which falls
In rain on the floors of the leaden
chambers. 1t is necessary to construct
these chambers of lead, because al
most any other material would be de-
stRoyed and eaten out by the action
Of 'this corrosive acid.
The phosphate rock is hauled to the
factory, usually a building located
alongside the sulphuric acid chambers,
it is there thrown into crushers watch
break 1t into small pieces; thence con
veyed to the grinding machinery,
either steel mills or buhr-stones, where
it is pulverized into fine meal or
flour. You would naturally ask at this
point, why not use this fine phosphate
meal directly on the soil, without mix
ing it with the caustic corrosive sui.
pnuric acid? 1t is simply because this
meal is Of a rocky nature and only dis.
solves with difficulty in the soil wa.
tiers, and we have seen plants require
their food to be easily soluble in water,
so that the roots can suck it in. The
phosphate rock meal, no matter how
finely ground, dissolves only to a very
limited extent in water, and it is nee.
essary to so treat it as to liberate tne
rock-bound phosphoric acid and render
It soluble in water. Hence the ne.
cessity for the sulphuric acid
The phosphate meal (say 1t is from
South Carolina rock, and contains
twenty-eight per cent. of phosphoric
acid, combined with lime to form six.
ty-One nc" cont Of horn phosphate
lime) is first weighed, and we will take
say one thousand pounds of it, and
dump it into circular cast-iron mixer
into which has already been intro.
duced one thousand pounds Of sulphur
ic acid Of the proper strength.
The acid and meal are now thorough
ly mixed together by machinery in the
iron pan. The mixture becomes very
not, the strong sulphuric acid attacks
the lime combined with the phosphoric
acid OF the phosphate meal with amaz
ing and furious energy and appropri.
ates to itself the greater part of the
lime In the form Of sulphate of lime
gypsum or land-plaster, and liberates
at the same moment the pnosphorie
acid, which is only allowed to retain
It's hold on small part of the lime
with which it was first combined.
This smaller portion of lime and the
phosphoric acid with which it is com.
btned is what the chemists call mono
ca1cdc phosphate, or superphosphate OF
lime. 1t is also known as the acid
phosphate Of lime This acid pnos.
phate of lime, or superphosphate, is
soluble in water; we have, therefore
accomplished what we set out to do
rendered the phosphoric acid soluble.
This discovery was made by the great
chemist LAebig, who thus put the en-
tire world in his debt, laying the found
atoms of the great fertilizer industry
and rendering an inestimable boon tc
modern agriculture.
JOHN M. McCANDLESS,
State Chemist.
Value of Corn Stalks.
The waste associated with tne norp